U.S. patent application number 13/977325 was filed with the patent office on 2013-10-31 for air conditioning system using outdoor air, indoor air unit, and outdoor air unit thereof, and stack.
This patent application is currently assigned to FUJI ELECTRIC CO., LTD. The applicant listed for this patent is Yuichiro Minegishi, Shunsuke Ohga, Masaki Takahashi. Invention is credited to Yuichiro Minegishi, Shunsuke Ohga, Masaki Takahashi.
Application Number | 20130283837 13/977325 |
Document ID | / |
Family ID | 46382956 |
Filed Date | 2013-10-31 |
United States Patent
Application |
20130283837 |
Kind Code |
A1 |
Takahashi; Masaki ; et
al. |
October 31, 2013 |
AIR CONDITIONING SYSTEM USING OUTDOOR AIR, INDOOR AIR UNIT, AND
OUTDOOR AIR UNIT THEREOF, AND STACK
Abstract
An air conditioning system using outdoor air has a first heat
exchanger, an evaporator, a condenser, and a first fan disposed on
the interior side; and a second heat exchanger and a second fan
disposed on the exterior side. An expansion valve and a compressor
are further provided. An air conditioner has a first piping
connected to the evaporator, the condenser, the expansion valve,
and the compressor, for circulating a first refrigerant to perform
a compression-type refrigeration cycle. An indirect outdoor air
cooler has a second piping connected to the first heat exchanger
and the second heat exchanger for circulating a second refrigerant
to induce a heat exchange in the first heat exchanger between the
second refrigerant and the indoor, and to induce a heat exchange in
the second heat exchanger between the outdoor air and the second
refrigerant.
Inventors: |
Takahashi; Masaki;
(Hachioji-shi, JP) ; Minegishi; Yuichiro;
(Hino-shi, Tokyo,, JP) ; Ohga; Shunsuke;
(Chiba-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Takahashi; Masaki
Minegishi; Yuichiro
Ohga; Shunsuke |
Hachioji-shi
Hino-shi, Tokyo,
Chiba-shi |
|
JP
JP
JP |
|
|
Assignee: |
FUJI ELECTRIC CO., LTD
Kawasaki-shi,
JP
|
Family ID: |
46382956 |
Appl. No.: |
13/977325 |
Filed: |
December 22, 2011 |
PCT Filed: |
December 22, 2011 |
PCT NO: |
PCT/JP2011/079778 |
371 Date: |
July 5, 2013 |
Current U.S.
Class: |
62/238.6 ;
62/333; 62/513 |
Current CPC
Class: |
F24F 12/00 20130101;
Y02B 10/24 20130101; F24F 2011/0006 20130101; H05K 7/20745
20130101; Y02A 30/272 20180101; Y02B 10/20 20130101; F24F 13/30
20130101; F24F 5/0046 20130101; F24F 1/022 20130101; F25B 25/005
20130101 |
Class at
Publication: |
62/238.6 ;
62/333; 62/513 |
International
Class: |
F24F 5/00 20060101
F24F005/00; F24F 12/00 20060101 F24F012/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2010 |
JP |
2010-293841 |
Jan 27, 2011 |
JP |
2011-014735 |
Claims
1-19. (canceled)
20. An air conditioning system using outdoor air, the air
conditioning system defining an interior side as an inside of a
building having indoor air, and an exterior side as an outside of
the building having the outdoor air, comprising: a first heat
exchanger disposed on the interior side; an evaporator disposed on
the interior side; a condenser disposed on the interior side; a
first fan disposed on the interior side for passing the indoor air
through the first heat exchanger, the evaporator and the condenser,
wherein the evaporator, the first heat exchanger and the condenser
are arranged in this order along passage of the indoor air by the
first fan; a second heat exchanger disposed on the exterior side; a
second fan disposed on the exterior side for passing the outdoor
air through the second heat exchanger; an expansion valve provided
on either the exterior side or the interior side; a compressor
provided on either the exterior side or the interior side; a first
piping connected to the evaporator, the condenser, the expansion
valve, and the compressor, for circulating a first refrigerant
through the first piping to the evaporator, the condenser, the
expansion valve and the compressor to perform a compression
refrigeration cycle, thereby forming an air conditioner; and a
second piping connected to the first heat exchanger and the second
heat exchanger, a second refrigerant being circulated through the
second piping to the first heat exchanger and the second heat
exchanger, the second refrigerant and an indoor air that has passed
through the condenser being heat exchanged by the first heat
exchanger, to thereby cool the indoor air, and the second
refrigerant being cooled by the outside air by heat exchanging the
inside air with the second refrigerant that has been cooled in the
second heat exchanger, thereby forming an indirect outdoor air
cooler.
21. An air conditioning system using outdoor air, comprising: an
indoor air unit for passing through indoor air, having: a first
heat exchanger; an evaporator; a condenser; and a first fan for
passing the indoor air through the first heat exchanger, the
evaporator, and the condenser, the condenser, the first heat
exchanger and the evaporator being arranged in this order from an
upstream side of an indoor air flown by the first fan; an outdoor
air unit for passing through the outdoor air, having: a second heat
exchanger; and a second fan for passing the outdoor air through the
second heat exchanger; an expansion valve provided on either one of
the outdoor air unit or the indoor air unit; a compressor provided
on either one of the outdoor air unit or the indoor air unit; a
first piping connected to the evaporator, the condenser, the
expansion valve, and the compressor, for circulating a first
refrigerant through the first piping to the evaporator, condenser,
expansion valve and compressor, to form an air conditioner by a
compression refrigeration cycle; and a second piping connected to
the first heat exchanger and the second heat exchanger, a second
refrigerant being circulated through the second piping to the first
heat exchanger and the second heat exchanger, the second
refrigerant and an indoor air that has passed through the condenser
being heat exchanged by the first heat exchanger, to thereby cool
the indoor air by the second refrigerant, and the second
refrigerant being cooled by the outside air by heat exchanging the
inside air with the second refrigerant that has been cooled in the
second heat exchanger, thereby forming an indirect outdoor air
cooler.
22. An air conditioning system using outdoor air according to claim
21, wherein the indoor air as a warm air flowing into the indoor
air unit and increasing a temperature in a cooling object space is
further heated by heat radiation from the condenser when passing
through the condenser and decreases a temperature of the first
refrigerant.
23. An air conditioning system using outdoor air according to claim
22, wherein a temperature of the indoor air raised in the condenser
is decreased by the heat exchange of the indoor air with the second
refrigerant when passing through the first heat exchanger, and the
indoor air is then cooled when passing through the evaporator,
becoming cold air, and is supplied into the cooling object space;
and the first refrigerant reduced in temperature in the condenser
circulates in an order of the expansion valve and the evaporator,
and cools the indoor air passing through the evaporator in the
evaporator.
24. An air conditioning system using outdoor air according to claim
21, wherein the outdoor air unit further comprises: a second
condenser; a branch piping branching off from the first piping and
connected to the second condenser; and a switching device provided
in a branching point of the first piping, for circulating the first
refrigerant in either the condenser in the indoor air unit or the
second condenser in the outdoor air unit.
25. An air conditioning system using outdoor air according to claim
21, wherein the outdoor air unit further comprises: a second
condenser connected to the first piping; and a switching device
disposed in a branching point in which the first piping is branched
on a refrigerant outflow side of the second condenser, wherein the
switching device switches routes for circulating the first
refrigerant to either a first route for circulating the first
refrigerant in the condenser in the indoor air unit and then
circulating in the expansion valve, or a second route for
circulating the first refrigerant in the expansion valve without
circulating in the condenser in the indoor air unit.
26. An air conditioning system using outdoor air according to claim
24, wherein the second heat exchanger is provided on an upstream
side of an outdoor air flow formed by the second fan, and the
second condenser is provided on a downstream side of the outdoor
air flow.
27. An air conditioning system using outdoor air according to claim
24, wherein the switching device circulates the first refrigerant
in the condenser when an outdoor air temperature is high and in the
second condenser when the outdoor air temperature is low.
28. An air conditioning system using outdoor air according to claim
25, wherein the switching device circulates the first refrigerant
in the first route when the outdoor air temperature is higher than
an indoor air temperature.
29. An indoor air unit for an air conditioning system using outdoor
air, which is disposed on an interior side of a building to pass an
indoor air therethrough and adapted to correspond to an outdoor air
unit disposed on an exterior side of the building to pass an
outdoor air therethrough, comprising: a first heat exchanger; an
evaporator; a condenser; a first fan for passing the indoor air
through the first heat exchanger, the evaporator, and the
condenser, wherein the evaporator, the first heat exchanger, and
the condenser are arranged in this order along passage of the
indoor air by the first fan; an expansion valve formed in the
indoor air unit; a compressor formed in the indoor air unit; a
first piping connected to the compressor, wherein an air
conditioner comprises the evaporator, the condenser, the expansion
valve and a part of the first piping, and a first refrigerant
passes the evaporator, the condenser, the expansion valve and the
compressor through the first piping to perform a compression
refrigeration cycle; and a second piping adapted to connect the
first heat exchanger to a second heat exchanger of the outdoor air
unit, a second refrigerant being circulated through the second
piping to the first heat exchanger and the second heat exchanger,
and in the first heat exchanger, the indoor air being heat
exchanged by the second refrigerant that has been cooled and the
outdoor air, to thereby cool the second refrigerant by the outdoor
air.
30. An outdoor air unit for an air conditioning system using
outdoor air, which is disposed on an outdoor side of a building to
pass an outdoor air therethrough and adapted to correspond to an
indoor air unit disposed on an interior side of the building to
pass an indoor air therethrough, comprising: a second heat
exchanger and a second fan for passing the outdoor air through the
second heat exchanger; an expansion valve; a compressor; a first
piping connected to the compressor, wherein an air conditioner is
adapted to comprise the evaporator, the condenser formed in the
indoor air unit, the expansion valve and a part of the first
piping, and a first refrigerant passes the evaporator, the
condenser, the expansion valve and the compressor through the first
piping to perform a compression refrigeration cycle; and a second
piping adapted to connect the second heat exchanger to a first heat
exchanger of an indoor air unit, a second refrigerant being
circulated through the second piping to the first heat exchanger
and the second heat exchanger, and in the second heat exchanger,
the indoor air being heat exchanged by the second refrigerant that
has been cooled and an outdoor air being heat, to thereby cool the
second refrigerant by the outdoor air.
31. A stack for cooling indoor air, which is disposed on an
interior side of a building to pass an indoor air therethrough and
adapted to correspond to an outdoor air unit disposed on an
exterior side of the building to pass an outdoor air therethrough,
comprising: a condenser for performing a compression refrigeration
cycle using a first refrigerant, and passing the indoor air
therethrough as warm air flowing into the indoor air unit and
raising a temperature in a cooling object space, said condenser
performing a heat radiation to raise a temperature of the indoor
air and decreasing a temperature of the first refrigerant; a first
heat exchanger for passing a second refrigerant therethrough that
was subject to a heat exchange with the outdoor air in the outdoor
air unit and the indoor air in which a temperature was increased in
the condenser, and inducing a heat exchange between the second
refrigerant and the indoor air; an evaporator for performing the
compression refrigeration cycle together with the condenser; and a
first fan, wherein the condenser, the first heat exchanger, the
evaporator, and the first fan are stacked and integrated.
32. A stack for moving heat of indoor air to outdoor air, which is
disposed on an outdoor side of a building to pass an outside air
therethrough and adapted to correspond to an indoor air unit
disposed on an interior side of the building to pass an interior
air therethrough, comprising: a second heat exchanger for passing
therethrough the outdoor air and a second refrigerant subject to a
heat exchange with the indoor air in the indoor air unit, and
inducing a heat exchange between the second refrigerant and the
outdoor air; and a second fan, wherein the second heat exchanger
and the second fan are stacked and integrated.
33. An air conditioning system using outdoor air, the air
conditioning system defining an interior side as an inside of a
building having indoor air, and an exterior side as an outside of
the building having the outdoor air, comprising: a first heat
exchanger disposed on the interior side; a condenser disposed on
the interior side; and a first fan disposed on the interior side,
for passing the indoor air through the first heat exchanger and the
condenser, wherein the condenser and the first heat exchanger are
provided in an order from an upstream side of an indoor air flow
formed by the first fan; an evaporator disposed either on the
exterior side or the interior side, an expansion valve disposed
either on the exterior side or the interior side, a compressor
disposed either on the exterior side or the interior side; a first
piping connected to the compressor disposed either on the exterior
side or the interior side, a first refrigerant being circulated
through the first piping to the evaporator, the condenser, the
expansion valve and the compressor to perform a compression
refrigeration cycle; and a second piping connected to the first
heat exchanger and the evaporator, a second refrigerant being
circulated through the second piping to the first heat exchanger
and the evaporator, the second refrigerant being cooled by the
first refrigerant by heat exchanging the first refrigerant and the
second refrigerant at the evaporator, and in the first heat
exchanger, the inside air being cooled by the second refrigerant by
heat exchanging the inside air with the second refrigerant that has
been cooled, thereby forming an indirect outdoor air cooler.
34. An air conditioning system using outdoor air, comprising: an
indoor air unit for passing indoor air therethrough, including: a
first heat exchanger; a condenser; and a first fan for passing the
indoor air through the first heat exchanger and the condenser,
wherein the indoor air unit is configured in an order of the
condenser and the first heat exchanger from an upstream side of an
indoor air flow formed by the first fan; an outdoor air unit for
passing the outdoor air therethrough; an evaporator disposed either
in the outdoor air unit or the indoor air unit; an expansion valve
disposed either in the outdoor air unit or the indoor air unit; a
compressor disposed either in the outdoor air unit or the indoor
air unit; a first piping connected to the compressor, wherein a
first refrigerant is circulated through the condenser, the
evaporator, the expansion valve, and the compressor, to perform a
compression refrigeration cycle; and a second piping connected to
the first heat exchanger and the evaporator, a second refrigerant
being circulated through the second piping to the first heat
exchanger and the evaporator, the second refrigerant being cooled
by the first refrigerant by heat exchanging the first refrigerant
and the second refrigerant at the evaporator, and in the first heat
exchanger, the inside air being cooled by the second refrigerant by
heat exchanging the inside air with the second refrigerant that has
been cooled, thereby forming an indirect outdoor air cooler.
35. An air conditioning system using outdoor air according to claim
33, further comprising: a second heat exchanger disposed on the
exterior side or in the outdoor air unit, and connected to the
second piping; and a second fan for passing the outdoor air through
the second heat exchanger; wherein the second refrigerant exchanges
heat with the outdoor air in the second heat exchanger and then
exchanges heat with the first refrigerant in the evaporator.
36. An air conditioning system using outdoor air according to claim
35, wherein the second piping includes a switching device to divide
the second piping into two branch pipes and to flow the second
refrigerant to one of the two branch pipes, one of the branch pipes
being connected to the second heat exchanger; and the switching
device is capable of switching between a state in which the second
refrigerant is circulated in the second heat exchanger, and a state
in which the second refrigerant is not circulated in the second
heat exchanger.
37. An air conditioning system using outdoor air according to claim
33, wherein the first heat exchanger is a liquid-gas heat
exchanger, and the evaporator is a liquid-liquid heat
exchanger.
38. An indoor air unit for an air conditioning system using outdoor
air, which is disposed on an interior side of a building to pass an
indoor air therethrough and adapted to correspond to an outdoor air
unit disposed on an exterior side of the building to pass an
outdoor air therethrough, comprising: a first heat exchanger; a
condenser; a first fan for passing the indoor air through the first
heat exchanger and the condenser, wherein the condenser and the
first heat exchanger are arranged in an order from an upstream side
of a flow of the indoor air formed by the first fan; an evaporator;
an expansion valve; a compressor; a first piping connected to the
compressor, wherein a first refrigerant is circulated through the
condenser, the evaporator, the expansion valve, and the compressor
to perform a compression refrigeration cycle; and a second piping
connected to the first heat exchanger and the evaporator, a second
refrigerant being circulated through the second piping to the first
heat exchanger and the evaporator, the second refrigerant being
cooled by the first refrigerant by heat exchanging the first
refrigerant and the second refrigerant in the evaporator, and in
the first heat exchanger, the indoor air being heat exchanged by
the second refrigerant that has been cooled and the indoor air to
cool the indoor air by the second refrigerant, thereby forming an
indirect outdoor air cooler.
Description
TECHNICAL FIELD
[0001] The present invention relates to an air conditioning system
using outdoor air.
BACKGROUND
[0002] For example, a large number of servers have been installed
in server rooms of data center or enterprises. The room temperature
in such server rooms rises due to heat generation by a large number
of servers and such increase in room temperature can result in
malfunction or damage of the servers. For this reason, an air
conditioning system has been used to maintain a constant
temperature inside the entire room. Such air conditioning system
operates practically at all times, even in winter.
[0003] In order to stabilize the temperature in the server room,
the conventional air conditioning system designed for such server
room uses a circulation system such that the low-temperature air
(cold air) blown from an air conditioning device and supplied into
the server room flows in contact with a server on a server rack,
thereby cooling the server, and the air (warm air) warmed up by the
heat of the server is returned from the server room into the air
conditioning device and cooled in the air conditioning device to
obtain again the cold air that is blown therefrom and again
supplied into the server room.
[0004] For example, the conventional techniques relating to such a
system are described in Patent Documents 1 and 2.
[0005] The invention disclosed in Patent Document 1 provides an air
conditioner that can operate in an energy saving mode and a
temperature-humidity controllability mode, while ensuring
sufficient high-frequency protection.
[0006] The invention disclosed in Patent Document 2 provides an air
conditioner in which good temperature controllability can be
obtained by suppressing interior temperature fluctuations caused by
changes in the number of operating units and which can operate in
an optimum mode designed with sufficient consideration for energy
saving ability, while ensuring sufficient high-frequency
protection. [0007] Patent Document 1: Japanese Patent No. 3361458
[0008] Patent Document 2: Japanese Patent No. 3320360
DISCLOSURE OF THE INVENTION
[0009] FIG. 14 shows an example of the conventional indirect
outdoor air cooling system.
[0010] In FIG. 14, the indirect outdoor air cooling system is
designed to cool any interior space and uses outdoor air for
cooling, without introducing the outdoor air into the interior
space. The interior space is, for example, a server room having
installed therein a server rack 202 carrying heating elements 201
such as server devices (computer devices) or the like. In such
interior space, a large amount of heat is generated by a large
number of heating elements 201, and the interior space should be
cooled even in winter.
[0011] In this example, the interior space is divided into a space
of server setting, an under-floor space, and an attic space. Among
them, the space of server setting is the space where the server
rack 202 carrying the heating elements 201 is installed. The
ceiling is above the space of server setting and the floor is
therebelow. The space above the ceiling is the attic space, and the
space below the floor is the under-floor space. Naturally, holes
are present in the floor and ceiling, and the cold air or warm air
flows into the space of server setting and therefrom.
[0012] In the indirect outdoor air cooling system shown in the
figure, the return air (warm air), for example, from the server
room, is cooled by a typical air conditioning device 210, but
energy consumption is reduced by decreasing the temperature of the
return air by using the outdoor air at the stage before the air
conditioning device.
[0013] The air conditioner 210 constituted by a refrigerator 211,
an air handling unit 212, an expansion valve 213, and a refrigerant
piping 214 shown in the figure is well-known typical air
conditioner. Thus, the air conditioner 210 is a typical air
conditioner (air conditioning device) that performs cooling in the
following typical compression-type refrigeration cycle (vapor
compression type refrigeration cycle or the like) by using a
refrigerant:
"evaporator.fwdarw.compressor.fwdarw.condenser.fwdarw.expansion
valve.fwdarw.evaporator".
[0014] The refrigerant circulates through the refrigerant piping
214 in the refrigerator 211, air handling unit 212, and expansion
valve 213. The refrigerator 211 has a compressor, a condenser, and
a fan. The air handling device 212 has an evaporator and a fan.
[0015] The air handling unit 212 delivers cold air into the
under-floor space in the interior space and supplies the cold air
through the under-floor space into the space of server setting. The
cold air is heated by cooling the heating elements 201, and the
warm air flows from the space of server setting into the attic
space. With the usual cooling system, the warm air is caused to
flow from the attic space into the air handling unit 212 through a
duct or the like. The air handling unit 212 generates the cold air
by cooling the inflowing warm air with the evaporator.
[0016] The air handling unit 212 cools the inflowing warm air so
that the temperature of the cold air assumes a predetermined value
(set value), and it is obvious that the load required for cooling
rises and power consumption increases as the temperature of the
inflowing air rises. Accordingly, with the object of saving the
energy, the indirect outdoor air cooler 220 is provided to reduce
the temperature of the warm air flowing into the air handling unit
212.
[0017] A wall 1 shown in the figure is that of any building, and
the exterior of the building is separated from the interior thereof
by the wall 1 as a boundary. The interior of the building includes
not only the interior space where the server is installed, but also
the space where the air handling unit 212 is provided (in the
example shown in the figure, it can be the space adjacent to the
interior space, for example, a machine room). The air in the
interior of the building (indoor air) circulates inside the
building, while repeatedly assuming the state of the cold air and
warm air. The air in the exterior of the building (outdoor air) may
be lower in temperature than the indoor air in the warm air state,
provided that the season is other than summer.
[0018] The indirect outdoor air cooler 220 has a heat exchanger
221, a fan 222, a fan 223, an indoor air duct 224, and an outdoor
air duct 225. The indoor air duct 224 is provided such that one end
thereof is at the attic space side and the other end thereof is at
the air handling unit 212 side. The indoor air duct is connected
along the way to the heat exchanger 221. The warm air of the attic
space in blown by the fan 222 into the indoor air duct 224 and also
discharged to the air handling unit 212 side, but passes along the
way through the heat exchanger 221.
[0019] Further, holes are provided in two random locations of the
wall 1 (one will be referred to as an outdoor air inflow hole 226
and the other as an outdoor air discharge hole 227). One end of the
outdoor air duct 225 is connected to the outdoor air inflow hole
226 and the other end is connected to the outdoor air discharge
hole 227. The outdoor air duct 225 is connected along the way to
the heat exchanger 221. The outdoor air is caused by the fan 223 to
pass through the outdoor duct 225. Thus, the outdoor air is caused
to flow in from the outdoor air inflow hole 226 and discharged from
the outdoor air discharge hole 227, but the outdoor air passes
along the way through the heat exchanger 221.
[0020] As mentioned hereinabove, in the conventional indirect
outdoor air cooling system, the indirect outdoor air cooler 220 is
newly added to the already installed typical air conditioner 210,
and the installation space is increased accordingly. Further, the
ducts (indoor air duct 224 and outdoor air duct 225), which are
shown in the simplified manner in the figure, actually take a large
installation space. The amount of power consumed by the fan 222 and
the fan 223, although being comparatively small, is also added. In
addition, the installation of the indirect outdoor air cooler 220
such as shown in FIG. 14 is time consuming and costly.
[0021] As mentioned hereinabove, the indoor air (warm air) and
outdoor air pass through the heat exchanger 221, and heat is
exchanged between the indoor air (warm air) and outdoor air inside
the heat exchanger 221. Where the heat exchanger 221 is used, the
heat exchange is performed while the outdoor air is separated from
the indoor air. As a result, the outdoor moisture, dust, and
corrosive gases contained in the outdoor air are not introduced
into the interior space and, therefore, the reliability of
electronic devices such as servers can be maintained. Further, such
heat exchanger 221 is of a well-known configuration which is not
described in detail herein.
[0022] Where the temperature of the indoor air is reduced by the
heat exchange in the heat exchanger 221, the temperature of the
warm air flowing into the air handling unit 212 decreases, and
power consumption in the air conditioner 210 is lowered (energy
saving effect is obtained). The power consumption in the fan 222
and the fan 223 may be assumed to be comparatively small.
[0023] The indoor air is cooled by the outdoor air to decrease the
temperature of the indoor air (warm air) essentially only when "the
temperature of the indoor air (warm air)>the temperature of the
outdoor air". Therefore, in a state in which the temperature of the
outdoor air is low, as in the winter, the effect of cooling the
indoor air (warm air) with the heat exchanger 221 is high and,
therefore, the energy saving effect in the air conditioner 210 is
high. Meanwhile, in the summer, the effect of cooling the indoor
air with the heat exchanger 221 is small, or no effect is obtained,
or even the reverse effect can be obtained. There are also regions
in which the outdoor air temperature is very high through almost
the entire year, as in hot climate zones, regardless of the
season.
[0024] Thus, the main problem associated with an air conditioning
system that cools the space where heating elements are present,
such as a server room, in particular, an air conditioning system
designed to save energy by using the outdoor air, is how to enable
the use of the outdoor air for cooling the interior space and save
the energy even when the outdoor air temperature is high. In
addition to this main problem, other problems are associated with
additional energy saving, size reduction, and cost reduction.
[0025] The present invention relates to an air conditioning system
that cools the interior space by using outdoor air to save energy,
and an object of the present invention is to provide an air
conditioning system using outdoor air that can realize the indoor
air cooling by using the outdoor air even when the outdoor air
temperature is high and can save energy in an air conditioning
system with a compression-type refrigeration cycle, and also to
provide an indoor air unit and an outdoor air unit for such air
conditioning system.
[0026] The air conditioning system using outdoor air in accordance
with the present invention comprises a configuration provided at
the interior side (inside the building) and a configuration
provided at the exterior side (outside the building). The air at
the interior side, in particular the return air (warm air) from the
cooling object space, is taken as the indoor air. The air at the
exterior side is the outdoor air.
[0027] A first heat exchanger, an evaporator, a condenser, and a
first fan for passing the indoor air through the first heat
exchanger, evaporator, and condenser are provided at the interior
side.
[0028] A second heat exchanger and a second fan for passing the
outdoor air through the second heat exchanger are provided at the
exterior side.
[0029] In addition, an expansion valve and a compressor are
provided. The expansion valve and compressor are each provided
either at the interior side or at the exterior side.
[0030] The system is arranged in the order of the condenser, first
heat exchanger, and evaporator from the upstream side of a flow of
the indoor air formed by the first fan. Therefore, the indoor air
first passes through the condenser, then passes through the first
heat exchanger and finally passes through the evaporator.
[0031] Additionally provided is a first piping connected to the
evaporator, condenser, expansion valve, and compressor. An air
conditioner of a compression-type refrigerant cycle is configured
by circulating a first refrigerant in the first piping through the
evaporator, condenser, expansion valve, and compressor.
[0032] Additionally provided is a second piping connected to the
first heat exchanger and the second heat exchanger. A second
refrigerant (for example, cooling liquid such as water) is
circulated in the second piping through the first heat exchanger
and the second heat exchanger.
[0033] An indirect outdoor air cooling system includes the first
heat exchanger, the second heat exchanger, and the second
refrigerant. Thus, the indoor air is cooled by the second
refrigerant by causing the second refrigerant to exchange heat in
the first heat exchanger with the indoor air that has passed
through the condenser. The second refrigerant is cooled by the
outdoor air by causing the indoor air to exchange heat with the
cooled second refrigerant and the outdoor air in the second heat
exchanger.
[0034] Here, the condenser radiates heat received by the evaporator
from the surroundings (indoor air) and is usually installed at the
exterior side (outside the building) to radiate heat to the outdoor
air. By contrast, in the abovementioned configuration, the
condenser is installed at the interior side (inside the building).
Therefore, the temperature of the indoor air is greatly increased
when the indoor air passes through the condenser. The indoor air
after this increase in temperature indirectly exchanges heat with
the outdoor air via the second refrigerant. Therefore, the indoor
air can be cooled by the outdoor air even when the outdoor air
temperature is very high.
[0035] Further, in the condenser, the refrigerant is cooled by the
indoor air. Therefore, in particular under the environment in which
the outdoor air temperature is higher than the indoor air
temperature (temperature before the indoor air passes through the
condenser), the effect of cooling the first refrigerant in the
condenser is comparatively high. In other words, when the first
refrigerant is cooled by the outdoor air by causing the outdoor air
to pass through the condenser, as in the usual case, the effect of
cooling the first refrigerant decreases under the environment in
which the outdoor air temperature is very high. Further, under the
environment in which "the outdoor air temperature>the indoor air
temperature", the effect of cooling the first refrigerant is higher
when the indoor air is used. As a result, in the configuration of
the present invention, the power consumption in the air conditioner
of a compression-type refrigeration cycle is reduced by comparison
with the conventional configuration at least under the
above-described environment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1 shows the configuration of the air conditioning
system of the first embodiment.
[0037] FIG. 2 shows the configuration of the air conditioning
system of the second embodiment.
[0038] FIG. 3 is an enlarged view of part of the configuration
shown in FIG. 2.
[0039] FIG. 4 shows the configuration of the air conditioning
system (variation 1) of the third embodiment.
[0040] FIG. 5A shows the configuration of the first example of the
air conditioning system (variation 2) of the third embodiment.
[0041] FIG. 5B shows the configuration of the second example of the
air conditioning system (variation 2) of the third embodiment.
[0042] FIG. 6 shows the operation model of the air conditioning
system of the third embodiment.
[0043] FIGS. 7A to 7D serve to compare the conventional
configuration with that of the third embodiment.
[0044] FIG. 8 is a modification of the configuration shown in FIG.
4.
[0045] FIG. 9 is a modification of the configuration shown in FIG.
5A.
[0046] FIG. 10 is a simplified configuration diagram of the entire
system including the air conditioning system of the third
embodiment.
[0047] FIG. 11 shows the configuration of the air conditioning
system (variation 1) of the fourth embodiment.
[0048] FIG. 12 shows the configuration of the air conditioning
system (variation 2) of the fourth embodiment.
[0049] FIG. 13 shows the operation model of the air conditioning
system of the fourth embodiment.
[0050] FIG. 14 shows an example of the conventional indirect
outdoor air cooling system.
BEST MODE FOR CARRYING OUT THE INVENTION
[0051] Embodiments of the present invention will be explained below
with reference to the drawings.
[0052] The "interior side" in the present invention means the
"interior of the building". Therefore, the "interior side" includes
not only the "interior space serving as a cooling object", but also
a machine room or the like. In other words, the "interior side", as
referred to herein, can be also said to represent the space where
the abovementioned "indoor air" (air inside the building) is
present. Likewise, the "exterior side" in the present invention
means the abovementioned "exterior of the building". In other
words, the "exterior side", as referred to herein, can be also said
to represent the space where the abovementioned "outdoor air" (air
outside the building) is present. Further, the "interior space" is
somewhat different in meaning from the "interior side" and is
assumed to mean the below-described "cooling object space to be
cooled by the indirect outdoor air cooling system (interior space
that is the cooling object), and in a more narrow sense, the space
of server setting included in the cooling object space." Therefore,
the "interior space" does not include the machine room or the
like.
[0053] FIG. 1 shows the configuration of the air conditioning
system (indirect outdoor air cooling system) of the first
embodiment.
[0054] In FIG. 1, the cooling object space that is to be cooled
with the indirect outdoor air system is assumed to be the same as
in the conventional example shown in FIG. 14. Thus, the interior
space which is the object of cooling is, for example, a server room
having installed therein a rack 102 carrying heating elements 101
such as server devices (computer devices). In the present example,
the space of server setting shown in the figure is divided into an
under-floor space and an attic space, in the same manner as in FIG.
14. This example, which is obviously not limiting, is used in the
present explanation. In this example, the cooling object can be
also interpreted, in the narrow meaning thereof, as the space of
server setting.
[0055] Further, similarly to the example shown in FIG. 14, the
interior of the building is separated from the exterior of the
building by a wall 1, and the air located inside the building
(indoor air) circulates while repeatedly assuming the state of the
cold air and warm air. The air in the exterior of the building
(outdoor air) is essentially assumed to be lower in temperature
that the indoor air in the warm air state.
[0056] Not only the interior space, but also the machine room are
present inside the building. As mentioned hereinabove, the machine
room is, for example, a space adjacent to the interior space and
connected to the under-floor space and attic space. The
below-described air handling unit 12 and indoor air unit 30 are
installed in the machine room.
[0057] In a simplified scheme, a typical air conditioner 10
supplies cold air to the interior space and generates the cold air
again by cooling the return air (warm air) from the interior space.
However, in the present system, the temperature of the return air
(warm air) is therebefore reduced by using the outdoor air.
[0058] In the example shown in the figure, the typical air
conditioner 10 delivers the cold air into the under-floor space,
supplies the cold air into the space of server setting via the
under-floor space, and cools the heating elements 101 by the cold
air. As a result, the cold air becomes the warm air, and this warm
air flows into the attic space and then returns as the return air
into the air conditioner 10. However, at the preceding stage of
this process, the temperature of the warm air is reduced using the
outdoor air in the indirect outdoor air cooler 20. The air
conditioner 10 may be identical to the typical conventional air
conditioner 210.
[0059] In the explanation below, the temperature of the outdoor air
is presumed to be low. The statement that "the temperature of the
outdoor air is low" does not indicate that the temperature of the
outdoor air is equal to or lower than a certain temperature, and
this low temperature depends on the temperature of the indoor air
(warm air). This assumption is the same as in the conventional
configuration. According to one approach, since the indirect
outdoor air cooling serves to reduce the temperature of the indoor
air (warm air) by using the outdoor air, the case in which the
temperature of the return air (warm air) can be decreased as a
result of such temperature reduction can be said to be realized
when the temperature of the outdoor air is low. In one example, as
mentioned hereinabove, the case in which the temperature of the
outdoor air is lower than the temperature of the indoor air (warm
air) is considered as the case in which "the temperature of the
outdoor air is low", but the embodiment is not limited to this
example.
[0060] In this case, the configuration that delivers the cold air
to the under-floor space is the typical air conditioner 10 shown in
the figure. This typical air conditioner 10 is constituted by a
refrigerator 11, an air handling unit 12, an expansion valve 13,
and a refrigerant piping 14. Those, refrigerant 11, air handling
unit 12, expansion valve 13, and refrigerant piping 14 may be the
same as the conventional refrigerant 211, air handling unit 212,
expansion valve 213, and refrigerant piping 214 shown in FIG.
14.
[0061] In other words, the air conditioner 10 shown in the figure
may be the same as the well-known typical air conditioner, such as
the conventional air conditioner 210. Therefore, the air handing
unit 12 has an evaporator 12a and a fan 12b shown in the figure
(the details of the configuration are neither shown in the figure
nor explained). Further, the refrigerator 11 has not only the fan
11a shown in the figure, but also a compressor and a condenser
which are not shown in the figure.
[0062] Thus, the typical air conditioner 10 has the evaporator 12a
and the compressor (not shown in the figure), condenser (not shown
in the figure) and the expansion valve 13, which are the components
of the typical air conditioner, and the refrigerant circulates
through the refrigerant piping 14 in those components. Thus, the
refrigerant circulates in the typical compression-type
refrigeration cycle (vapor compression-type refrigeration cycle or
the like):
"evaporator.fwdarw.compressor.fwdarw.condenser.fwdarw.expansion
valve.fwdarw.evaporator". In the evaporator 12a, the heat is drawn
by the evaporating refrigerant from the surrounding air, thereby
cooling the surrounding air (inflowing warm air). The received heat
is radiated by the condenser to the outdoor air. The outdoor air is
blown by the fan 11a to the condenser (not shown in the figure),
and the condenser (not shown in the figure) radiates the heat to
the outdoor air as mentioned hereinabove. It goes without saying,
that the outdoor air is thereafter discharged to the outside of the
refrigerator 11.
[0063] The wall 1 shown in the figure is that of any building, and
the interior space and the space adjacent to the interior space
(machine room) are present inside the building. The air handling
unit 12 and the below-described indoor air unit 30 are installed in
the machine room, and the refrigerator 11 and the below-described
outdoor air unit 40 are installed outside the building. The indoor
air circulates inside the building (interior space and machine
room), while repeatedly assuming the warm air state and cold air
state, and the outdoor air is present outside the building.
[0064] The typical air conditioner 10 is explained hereinabove in a
simple manner, and similarly to case of the above-described
conventional air conditioner 210, it is desirable that the amount
of power consumed by the typical air conditioner 10 be decreased by
reducing the temperature of the return air (warm air) flowing into
the air handing unit 12 of the typical air conditioner 10. Even if
the amount of power consumed by the typical air conditioner 10 is
decreased, it is meaningless if the total power consumption is
increased. As a result, a method for reducing the temperature of
the indoor air (warm air) by using die outdoor air has been
considered and the conventional system has been provided with the
indirect outdoor air cooler 220.
[0065] By contrast, in the present example, the indirect outdoor
air cooler 20 shown in the figure is provided.
[0066] The indirect outdoor air cooler 20 is explained below in
greater detail.
[0067] The indirect outdoor air cooler 20 is constituted by the
indoor air unit 30 and the outdoor air unit 40.
[0068] The indoor air unit 30 and the outdoor air unit 40 are, for
example, individually manufactured at respective plants and then
installed so as to be in close contact with the surfaces of the
wall 1 (with the inner wall and outer wall, respectively, as shown
in the figure).
[0069] The exterior side (outside the building) and the interior
side (inside the building) are separated by the wall 1 as a
boundary. The outdoor air unit 40 is installed on the exterior
side, and the indoor air unit 30 is installed on the interior side.
In other words, the outdoor air unit 40 is installed so as to be in
close contact with the wall surface on the exterior side of the
wall 1. The indoor air unit 30 is installed so as to be in close
contact with the wall surface on the interior side of the wall
1.
[0070] For example, the indoor air unit 30 has a liquid-gas heat
exchanger 31, a fan 32, a piping 21 (part thereof, about half), and
a circulating pump 22 shown in the figure.
[0071] For example, the outdoor air unit 40 has a liquid-gas heat
exchanger 41, a fan 42, and a piping 21 (part thereof, about half)
shown in the figure.
[0072] When the indoor air unit 30 is manufactured at a plant, for
example, the liquid-gas heat exchanger 31 and the fan 32 shown in
the figure are provided inside a box-like housing which is open at
one surface (this surface is absent). Further, two holes (indoor
air inlet 33 and indoor air outlet 34) shown in the figure are
provided in the housing. The piping 21 (piping 21 connected along
the way to the circulating pump 22) shown in the figure may be
already connected to the liquid-gas heat exchanger 31 when the
indoor air unit is manufactured at a plant, or may be connected to
the liquid-gas heat exchanger 31 at the time of installation.
Alternatively, only the piping 21 may be connected at a plant and
the circulating pump 22 may be connected to the piping 21 at the
time of installation.
[0073] When the outdoor air unit 40 is manufactured at a plant, for
example, the liquid-gas heat exchanger 41 and the fan 42 shown in
the figure are provided inside a box-like housing which is open at
one surface (this surface is absent).
[0074] The indoor air unit 30 and the outdoor air unit 40 are
installed so that the open surfaces thereof mate with the surface
of the wall 1.
[0075] Further, two holes (outdoor air inlet 43 and outdoor air
outlet 44) shown in the figure are provided in the housing of the
outdoor air unit 40. The piping 21 shown in the figure may be
already connected to the liquid-gas heat exchanger 41 when the
indoor air unit is manufactured at a plant, or may be connected to
the liquid-gas heat exchanger 41 at the time of installation.
[0076] At the time of installation, through holes for allowing the
piping 21 to pass therethrough should be provided in two locations
in the wall 1. When the piping 21 (part thereof, about half) is
already provided at the indoor air unit 30 and the outdoor air 40
during the manufacture at a plant, the "piping 21 connected along
the way to the circulating pump 22", which is shown in the figure,
is formed, e.g., by welding one piping 21 to the other (at this
time, the circulating pump 22 is also connected).
[0077] The indirect outdoor air cooler 20 is configured by
installing the indoor air unit 30 and the outdoor air unit 40 in
the above-described manner.
[0078] Since the heat exchange is performed in a state in which the
outdoor air is separated from the indoor air, in the indirect
outdoor air cooler 20, the heat exchange is performed while the
outdoor air and indoor air are separated from each other, in the
same manner as in the conventional system shown in FIG. 14.
Therefore, the outdoor air moisture, dust, and corrosive gases
contained in the outdoor air are not introduced into the interior
space. As a result, the reliability of the electronic devices such
as servers can be maintained.
[0079] As mentioned hereinabove, it is necessary that holes for the
piping 21 be provided in the wall 1, but the size of the holes can
be reduced by comparison with that of the holes 226 and 227 for
inflow and discharge of the outdoor air, as in the conventional
configuration, and the installation operation is facilitated.
[0080] In the above-described example, a total of two piece of
piping 21 are used, one for conveying the refrigerant from the
outdoor air unit into the indoor air unit and the other for
conveying the refrigerant from the indoor air unit into the outdoor
air unit, and the through holes of the wall 1 are formed in two
locations. However, the embodiments of the present invention are
not limited to this example. For example, it is possible to form a
large through hole in one location and pass the two pieces of
piping 21 through this large hole.
[0081] In the above-described example, both the indoor air unit 30
and the outdoor air unit 40 are installed so that the open surfaces
thereof match the surface of the wall 1, but the embodiments of the
present invention are not limited to this example. For example, it
is possible to manufacture the indoor air unit 30 and the outdoor
air unit 40 as an integrated indoor-outdoor air unit after welding
the pieces of piping 21 at a plant, provides an orifice of the same
shape as the integrated indoor-outdoor air unit in the wall 1 and
embed the indoor-outdoor air unit into the wall.
[0082] The fan 32 in the indoor air unit 30 after the
abovementioned installation creates the air flow (shown by a
dot-dash arrow in the figure) such that the warm air of the attic
space flows from the indoor air inlet 33 and passes through inside
the indoor air unit 30 (in particular, inside the liquid-gas heat
exchanger 31), and is then discharged from the indoor air outlet
34. Basically, the temperature of the warm air discharged from the
indoor air outlet 34 is lower than the temperature of the warm air
flowing in from the indoor air inlet 33.
[0083] The warm air discharged from the indoor air outlet 34 flows
into the air handling unit 12 and is cooled by the evaporator 12a
inside the air handling unit 12 to become the cold air. This cold
air is blown by the fan 12b into the under-floor space. By reducing
the warm air temperature as mentioned hereinabove, it is possible
to reduce the power consumed in the typical air conditioner 10 by
comparison with the case in which the warm air located in the attic
space flows directly into the air handling unit 12.
[0084] In the outdoor air unit 40 after the abovementioned
installation, the fan 42 causes the outdoor air to flow in from the
outdoor air inlet 43 and pass through inside the outdoor air unit
40 (in particular, in the liquid-gas heat exchanger 41), and then
creates the air flow (shown by a dot-dash arrow in the figure) such
that is discharged from the outdoor air outlet 44.
[0085] In this configuration, the circulating pump 22 is connected
to any location in the piping 21, and the refrigerant such as a
liquid (for example, water) is sealed inside the piping. As a
result, where the circulating pump 22 is operated, this liquid (for
example, water) circulates in the liquid-gas heat exchanger 31 and
the liquid-gas heat exchanger 41 via the piping 21. The liquid-gas
heat exchanger 31 may be identical to the liquid-gas heat exchanger
41.
[0086] The liquid-gas heat exchangers 31 and 41 have well-known
configurations and only briefly described below, without being
explained in greater detail. In the conventional heat exchanger
221, two gases (both are the air, namely, the indoor air (warm air)
and outdoor air) are caused to pass through inside the heat
exchanger and heat is exchanged between the two gases, whereby the
indoor air (warm air) is cooled by the outdoor air when the outdoor
air temperature is low. In the liquid-gas heat exchangers 31 and
41, a liquid (for example, water) and a gas (in this case, the air)
are caused to pass through inside the heat exchanger and heat is
exchanged between the liquid and the gas, thereby cooling the fluid
with a higher temperature.
[0087] The gas (air) is the indoor air (warm air) in the liquid-gas
heat exchanger 31 and the outdoor air in the liquid-gas heat
exchanger 41. Further, the liquid is water circulated by the piping
21 and the circulating pump 22.
[0088] Where the outdoor air temperature is low, the heat exchange
between the liquid (water or the like) and the outdoor air in the
liquid-gas heat exchanger 41 reduces the temperature of the liquid
(water or the like), and the temperature of the outdoor air rises.
The liquid (water or the like) with a lower temperature flows
through the piping 21 into the liquid-gas heat exchanger 31. As a
result, heat exchange is performed in the liquid-gas heat exchanger
31 between the liquid (water or the like) with a comparatively low
temperature and the indoor air (warm air). As a consequence, the
temperature of the indoor air (warm air) drops and the temperature
of the liquid (water or the like) rises. Therefore, the liquid
(water or the like) that has assumed a comparatively high
temperature flows through the piping 21 into the liquid-gas heat
exchanger 41 and is cooled again in the above-described manner by
the outdoor air. As a result, the outdoor air with raised
temperature is discharged from the outdoor air outlet 44.
[0089] In the configuration shown in FIG. 1, the fan 32 causes the
air to flow downward (the direction from top to bottom) inside the
indoor air unit 30, but the air can be also caused to flow upward
(the direction from bottom to top). Likewise, in the configuration
shown in FIG. 1, the fan 42 causes the air to flow upward inside
the outdoor air unit 40, but the air can be also caused to flow
downward.
[0090] However, it is preferred that the flow of air inside the
indoor air 30 be a downward flow as shown in FIG. 1. In such a
case, the warm air warmed up by the heating elements 101 is at the
top, and the air cooled in the liquid-gas heat exchanger 31 flows
downward and, therefore, the circulation of air inside the indoor
air unit 30 corresponds to natural phenomenon and does not proceed
against the natural convection.
[0091] The process for manufacturing and installing the indirect
outdoor air cooler 20 will be explained below.
[0092] In the example shown in FIG. 1, the outdoor air unit 40 and
the indoor air unit 30 have substantially the same shape and
dimensions of the housings thereof (therefore, the surface area for
mounting on the wall is substantially the same), and the units are
disposed and integrated to ensure substantially left-right symmetry
with respect to the wall 1, thereby forming the indirect outdoor
air cooler 20. The left-right direction as referred to herein
relates to the figure.
[0093] When the units are installed, for example, first, a
plurality of through holes is formed in the wall 1. Then, the
outdoor air unit 40 and the indoor air unit 30 are disposed at
positions such that the frames of the housings thereof sandwich the
wall 1 in a left-right symmetrical configuration (in other words,
the frames are disposed at substantially identical positions, with
the wall 1 therebetween, as shown in FIG. 1), and the outdoor air
unit 40 and the indoor air unit 30 are fixed with bolts and nuts
through a plurality of through holes drilled in the wall 1 at the
positions of the plurality of through holes. The pieces of piping
21 are then connected via separate through holes.
[0094] In the example shown in FIG. 1, the outdoor air unit 40 and
the indoor air unit 30 are substantially identical in terms of not
only the housings thereof, but also the internal configurations
(substantially left-right symmetrical, as shown in the figure), and
the difference therebetween is only in the presence of the
circulating pump 22. Therefore, for example, the units configured
to include no circulating pump 22 are manufactured at a plant,
without distinguishing between the indoor air units and outdoor air
units, and the manufactured unit can be used as either of the
outdoor air unit 40 and the indoor air unit 30 during the
installation. When the manufactured unit is used as the indoor air
unit 30, the circulating pump 22 should be connected at the time of
installation. However, with such an approach, the production
efficiency at the plant rises and, therefore, a cost-reduction
effect can be expected.
[0095] With the above-described indirect outdoor air cooler 20, the
following effects are demonstrated.
[0096] Thus, in the indirect outdoor air cooler 20, the pair of
liquid-gas heat exchangers 31 and 41 in which the internal fluid is
liquid and the external fluid is gas is disposed inside and outside
the building, respectively, with the wall 1 being interposed
therebetween, the outdoor air is caused to flow as the external
fluid of one liquid-gas heat exchanger 41, the indoor air is caused
to flow as the external fluid of the other liquid-gas heat
exchanger 31, and the internal fluids (liquids) of the two
liquid-gas heat exchangers are circulated via the piping 21. As a
result, heat exchange is performed between the outdoor air and the
indoor air.
[0097] Because of the above-described feature, the indirect outdoor
air cooler 20 demonstrates the following effects.
[0098] (1) Since the outdoor air unit 40 having the liquid-gas heat
exchanger 41 with the outdoor air flowing therethrough and the
indoor air unit 30 having the liquid-gas heat exchanger 31 with the
indoor air flowing therethrough are disposed and integrated to be
left-right symmetrical with respect to the wall 1 as a center, it
is possible to use the units 30 and 40 that have frames of
substantially the same structure and the production cost can be
reduced.
[0099] (2) Further, since the outdoor air unit 40 and the indoor
air unit 30 are fixed with bolts and nuts through a plurality of
through holes drilled in the wall 1 at the positions of the
plurality of through holes when the indirect outdoor air cooler 20
is installed, the installation cost can be reduced and the
installation operations can be facilitated.
[0100] (3) The duct portion can be reduced in size and the pressure
loss caused by duct resistance can be reduced by comparison with
those of the conventional system shown in FIG. 14.
[0101] The air conditioning system (integrated air condition
system) of the second embodiment will be explained below.
[0102] The air conditioning system of the second embodiment is also
an indirect outdoor air cooling system, but has an integrated
compact configuration.
[0103] In the indirect outdoor air cooling system of the first
embodiment, a ductless compact configuration that is simple to
install is suggested for the indirect outdoor air cooler 20, but
the typical air conditioner 10 is substantially the same as in the
conventional system.
[0104] In the second embodiment, an integrated indirect outdoor air
cooling system is suggested in which the function of the indirect
outer air cooler 20 and the function of the typical air conditioner
10 are integrated.
[0105] As a result, the entire device configuration can be
simplified, the device can be reduced in size and cost, and the
total power consumption can be also expected to reduce.
[0106] FIG. 2 shows the configuration of the air conditioning
system (integrated air conditioning system) of the second
embodiment.
[0107] FIG. 3 is a enlarged view of part of the configuration shown
in FIG. 2.
[0108] In FIG. 2, the cooling object space to be cooled in the
indirect outdoor air cooling system is assumed to be the same as in
the example shown in FIGS. 1 and 14. Thus, the interior space that
is the object of cooling is, for example, a server room having
installed therein a large number of server racks 102 carrying
heating elements 101 such as server devices (computer devices). The
cold air is delivered into the under-floor space, the cold air is
supplied via the under-floor space into the space of server
setting, and the heating elements 101 are cooled by the cold air.
As a result, the cold air becomes the warm air, and the warm air
flows into the attic space.
[0109] The configuration for delivering the cold air into the
under-floor space is an integrated indirect outdoor air cooling
system 50 shown in the figure. The integrated indirect outdoor air
cooling system 50 has the configuration in which the function of
the indirect outdoor air cooler and the function of the typical air
conditioner are integrated. In the indirect outdoor air cooling
system 50, the warm air of the attic space is caused to flow in,
the temperature of the warm air is initially decreased by the
function of the indirect outdoor air cooler, and then the cold air
of a predetermined temperature is generated by the function of the
typical air conditioner. The integrated indirect outdoor air
cooling system will be explained below in greater detail with
reference to FIGS. 2 and 3.
[0110] The integrated indirect outdoor air cooling system 50 is
constituted by an indoor air unit 60 and an outdoor air unit 70
shown in FIGS. 2 and 3.
[0111] When the indirect outdoor air cooler of the indirect outdoor
air cooling system 50 functions, the heat exchange is performed
while the outdoor air is separated from the indoor air, in the same
manner as in the configuration of the conventional example shown in
FIG. 14 or the configuration shown in FIG. 1. As a result, the
outdoor moisture, dust, and corrosive gases contained in the
outdoor air are not introduced into the interior space and,
therefore, the reliability of electronic devices such as a server
can be maintained.
[0112] The indoor air unit 60 and the outdoor air unit 70 are, for
example, manufactured individually at respective plants and then
installed so as to be in close contact with the surfaces of the
wall 1, as shown in the figure. In this case, the integrated
indirect outdoor air cooling system 50 is configured by
additionally installing a piping 51 and a refrigerant piping 52
shown in the figure (or manufacturing them in sections, each being
about half of the product, and connecting (by welding or the like)
the sections together). Through holes should be provided in the
wall 1 in order to install the piping 51 and the refrigerant piping
52, and those through holes are configured as shown in FIG. 1 or
FIG. 14 and provided in four locations. The structure and
installation of the indoor air unit 60 and the outdoor air unit 70
are substantially the same as those of the indoor air unit 30 and
the outdoor air unit 40 of the first embodiment, and detailed
explanation thereof is herein omitted.
[0113] The exterior side (outside the building) and the interior
side (inside the building) are separated by the wall 1 as a
boundary. The outdoor air unit 70 is installed on the exterior
side, and the indoor air unit 60 is installed on the interior side.
In other words, the outdoor air unit 70 is installed so as to be in
close contact with the wall surface on the exterior side of the
wall 1. The indoor air unit 60 is installed so as to be in close
contact with the wall surface on the interior side of the wall
1.
[0114] The outdoor air unit 70 and the indoor air unit 60 are
preferably provided at mutually corresponding positions, with the
wall 1 being interposed therebetween. The mutually corresponding
positions, with the wall 1 being interposed therebetween, as
referred to herein, are, for example, the positions such as shown
in FIG. 2 or FIG. 3. For example, when viewed from the outdoor air
unit 70 side, the positions are such that the indoor air unit 60 is
present on the rear side of the wall 1. In other words, assuming
that the housing of the outdoor air unit 70 and the housing of the
indoor air unit 60 have substantially the same shape and
dimensions, as shown in the figure, the two housings are disposed
so as to be in a substantially symmetrical relationship
(substantially left-right symmetry) with respect to the wall 1, as
shown in the figure. It goes without saying that the embodiment is
not limited to this, and it is basically desirable that the units
be installed in a manner such that facilitates the installation and
shortens the piping.
[0115] The indoor air unit 60 has a stack 61. The stack 61 has an
evaporator 61a, a liquid-gas heat exchanger 61b, and a fan 61c and
configured by stacking and integrating those components as shown in
the figure. The configuration in which the evaporator, liquid-gas
heat exchanger, and fan are thus integrated as a stack have
significant merits, but the embodiment is not limited to this
configuration. However, since the specific feature of the second
embodiment is the "integrated" unit, it is necessary that the
evaporator, liquid-gas heat exchanger, and fan be provided inside
the indoor air unit 60:
[0116] Holes such as an indoor air inlet 62 and an indoor air
outlet 63 shown in the figure are provided in the housing (for
example, a box open at one side) of the indoor air unit 60. The fan
61c produces the flow of air (shown by a dot-dash arrow in the
figure) such that the warm air of the attic space flows from the
indoor air inlet 62 into the unit 60 and passes through inside the
indoor air unit 60 (in particular, inside the stack 61) and is then
discharged from the indoor air outlet 63.
[0117] The stack 61 is configured such that the liquid-gas heat
exchanger 61b is provided on the upstream side of such air flow and
the evaporator 61a is provided on the downstream side. Therefore,
the embodiment shown in the figure is not limited to this
configuration and any configuration satisfying this condition can
be used.
[0118] Further, even when a configuration other than stack
(integrated) is used (such a configuration is not shown in the
figures), it is necessary to provide a liquid-gas heat exchanger on
the upstream side of air flow and provide an evaporator on the
downstream side. In other words, a configuration is required in
which the temperature of the indoor air (warm air) is so regulated
that after the temperature has been reduced in the liquid-gas heat
exchanger, the predetermined temperature (set temperature) is
obtained in the evaporator.
[0119] The description above relates to the positional relationship
of the liquid-gas heat exchanger 61b and the evaporator 61a, and
the fan 61c may be arranged at any position in the stack 61
(arrangement order with respect to the air flow). In other words,
the fan 61c may be at any of the most upstream position, most
downstream position, or intermediate position (between the
liquid-gas heat exchanger 61b and the evaporator 61a) of the air
flow. The same is true for a configuration other than stack and
substantially true for the below-described other stacks 71, 81, 91,
91', 111, 121, and 121'.
[0120] The outdoor air unit 70 has the stack 71. The stack 71 has a
condenser 71a, a liquid-gas heat exchanger 71b, and a fan 71c, and
configured by stacking and integrating those components as shown in
the figure. Similarly to the indoor air unit 60, the configuration
of the outdoor air unit is not limited to the stack. However,
similarly to the indoor air unit 60, a condenser, a liquid-gas heat
exchanger, and a fan should be provided inside the outdoor air unit
70.
[0121] Further, holes such as an outdoor air inlet 72 and an
outdoor air outlet 73 shown in the figure are provided in the
housing of the outdoor air unit 70. The fan 71c creates an air flow
(shown by a dot-dash arrow in the figure) such that the outdoor air
flows from the outdoor air inlet 72 into the unit 70, passes
through inside the outdoor air unit 70 (in particular, inside the
stack 71), and flows out from the outdoor air outlet 73. The stack
71 is configured such that the liquid-gas heat exchanger 71b is
provided on the upstream side of this air flow, and the condenser
71a is provided on the downstream side. Further, as has already
been mentioned above, in this stack 71, the fan 71c may be provided
at any position (arrangement order with respect to the air flow),
substantially in the same manner as in the stack 61 (therefore, a
suitable arrangement is not limited to the example shown in the
figure, and any configuration satisfying the abovementioned
condition may be used). This is also true for a configuration other
than the stack.
[0122] As mentioned hereinabove, the configurations of the indoor
air unit 60 and the outdoor air unit 70 shown in FIGS. 2 and 3 are
exemplary and not being limited to this. Substantially the same is
true with respect to the configurations shown in FIG. 4 and
subsequent figures.
[0123] The stacks 61 and 71 may have various configurations and may
be manufactured by a variety of methods which are not explained in
detail herein. However, the configuration that is easy to
manufacture and/or compact and the production method thereof are
preferred. For example, in the case of the stack 61, the evaporator
61a, liquid-gas heat exchanger 61b, and fan 61c may be accommodated
in respective housings (formed as units) and those housings may
have substantially the same dimensions and shape. Further, for
example, the housings may have a rectangular parallelepiped shape,
and the stack 61 may be also provided with a substantially
rectangular parallelepiped shape by stacking those three
rectangular parallelepipeds.
[0124] In this example, the evaporator 61a, liquid-gas heat
exchanger 61b, and fan 61c are stacked and integrated (the stack 61
is formed), for example, by connecting the abovementioned housings
to each other. The connection of the housings to each other may be
performed, for example, by a typically used method, such as
inserting a rod or bolt into the holes provided in the corners of
the housings and tightening with nuts.
[0125] It goes without saying that a large number of holes for
allowing the indoor air unit to pass therethrough and holes for
passing various pipes are provided in the housings.
[0126] In this case, the liquid-gas heat exchangers 61b and 71b are
connected to each other by the piping 51, substantially in the same
manner as the liquid-gas heat exchangers 31 and 41 of the first
embodiment, and the liquid (water or the like) located in the
piping 51 is circulated inside the liquid-gas heat exchangers 61b
and 71b and the piping 51 by the circulating pump 53. The
liquid-gas heat exchangers 61b and 71b may have a well-known
configuration and may be configured similarly to the liquid-gas
heat exchangers 31 and 41; the configuration thereof is not
explained in detail herein.
[0127] The liquid (water or the like) and the indoor air (warm air)
pass through inside the liquid-gas heat exchanger 61b. As a result,
heat exchange is performed between the liquid (water the like) and
warm air inside the liquid-gas heat exchanger 61b and, essentially,
the warm air is cooled (the heat of the warm air moves to the
liquid) and the temperature of the warm air decreases. This,
however, depends on the temperature of the outer air and warm air
and does not guarantee that the temperature of the warm air drops.
Where the temperature of the outdoor air is high, the circulating
pump 53 can be stopped.
[0128] A refrigerant piping 52, an expansion valve 54, and a
compressor 55 are provided in addition to the evaporator 61a and
condenser 71a. The configuration of each component is substantially
identical to that in the typical air conditioner 10. Thus, in a
typical air conditioner 10, the evaporator 12a and fan 12b are
provided in the air handling unit 12, and the evaporator 61a is
configured correspondingly to the evaporator 12a. Further, as
mentioned hereinabove, a compressor and a condenser (not shown in
the figure) are provided in the refrigerator 11, and the compressor
55 and condenser 71a are the components corresponding thereto. The
expansion valve 54 is configured correspondingly to the expansion
valve 13.
[0129] As shown in the figure, the evaporator 61a, condenser 71a,
expansion valve 54, and compressor 55 are connected to the
refrigerant piping 52. The refrigerant circulates in the evaporator
61a, condenser 71a, expansion valve 54, and compressor 55 via the
refrigerant piping 52. Thus, the refrigerant circulates in the
typical compression-type refrigeration cycle (vapor
compression-type refrigeration cycle or the like): "evaporator
61a.fwdarw.compressor 55.fwdarw.condenser 71a.fwdarw.expansion
valve 54.fwdarw.evaporator 61a". When the refrigerant is evaporated
in the evaporator 61a, the heat is drawn from the surroundings and
the surroundings are cooled. This heat is radiated to the outdoor
air in the condenser 71a. The expansion valve 54 and the compressor
55 function in the conventional manner which is not explained in
detail herein.
[0130] As shown in the figure, the expansion valve 54 is provided
in the indoor air unit 60, but it may be also provided in the
outdoor air unit 70. The compressor 55 is provided in the outdoor
air unit 70, but it may be also provided in the indoor air unit 60.
In other words, it is possible to use the configuration in which
the expansion valve 54 is provided in the indoor air unit 60 and
the compressor 55 is provided in the outdoor air unit 70, the
configuration in which the expansion valve 54 is provided in the
outdoor air 70 and the compressor 55 is provided in the indoor air
unit 60, the configuration in which the expansion valve 54 and the
compressor 55 are both provided in the indoor air unit 60, and the
configuration in which the expansion valve 54 and the compressor 55
are both provided in the outdoor air unit 70.
[0131] In the example shown in the figure, the circulating pump 53
is provided in the indoor air unit 60, but it may be also provided
in the outdoor air unit 70.
[0132] The liquid-gas heat exchanger 61b and the liquid-gas heat
exchanger 71b are heat exchangers performing heat exchange between
liquid and gas, but the embodiment is not limited to this example.
Thus, heat exchangers performing heat exchange between gas and gas
(will be referred to as gas-gas heat exchangers) may be provided
instead of those liquid-gas heat exchangers. Obviously, in this
case, some gas is used instead of the liquid.
[0133] Where a general term "fluid" is used to describe such
liquids and gases, the liquid-gas heat exchangers and gas-gas heat
exchangers may be generally referred to as fluid-gas heat
exchangers or fluid-fluid heat exchangers. In this case, it can be
said that a certain "fluid" flows in the piping 51. In other words,
it can be said that any "fluid" can be circulated in two heat
exchangers (the liquid-gas heat exchanger 61b and the liquid-gas
heat exchanger 71b in the example shown in the figure, but the
embodiment is not limited to this example, as mentioned
hereinabove) via the piping 51. The same is substantially true for
other below-described configurations. Thus, the liquid-gas heat
exchangers may be replaced with gas-gas heat exchangers in the
below-described configurations using the liquid-gas heat exchangers
81b and 91c and a piping 96, liquid-gas heat exchangers 111b and
121c and a piping 126, and liquid-gas heat exchangers 111b and 171c
and a piping 162, and it may be said that some "fluid" is
circulated.
[0134] Each component of the integrated indirect outdoor air
cooling system 50 is explained above.
[0135] The operation of the integrated indirect outdoor air cooling
system 50 of the above-described configuration will be explained
below with reference to FIG. 3.
[0136] Thus, where the indoor air (warm air) of the attic space
flows into the indoor air unit 60 via the indoor air unit inlet 62,
first, the warm air passes through inside the liquid-gas heat
exchanger 61b, whereby heat exchange is performed between the warm
air and the liquid (water or the like), and the temperature of the
warm air decreases. The degree of this decrease depends on the
temperature of the outdoor air (the temperature of the liquid) and
the temperature of the warm air.
[0137] The warm air reduced in temperature then passes through the
evaporator 61a. As a result, the warm air reduced in temperature is
cooled in the evaporator 61a, assumes an even lower temperature and
becomes cold air. The control is performed such that cold air
assumes a predetermined temperature (set temperature). A controller
74 which is not depicted in the figure (shown only schematically in
FIG. 3) is used for such control. The controller 74 controls the
entire integrated indirect outdoor air cooling system 50 and also
controls, for example, the revolution speed of the fans and the
circulating pump 53, but such control is not explained herein. The
controller 74 includes a computational device such as a CPU and a
storage device such as a memory and executes a program that has
been stored in advance in a memory or the like, thereby controlling
the integrated indirect outdoor air cooling system by appropriately
inputting the measured values from various sensors (not shown in
the figure).
[0138] Further, the controller 74 may be provided inside the
housing of the indoor air unit or inside the housing of the outdoor
air unit, or outside those units (in the vicinity of the units). In
FIG. 3, various signal wires relating to the controller 74 are not
shown, but they are actually present and the controller 74 controls
various components of the integrated indirect outdoor air cooling
system 50 via the signal wires. For example, a temperature sensor
(not shown in the figure) is provided in the vicinity of the blow
port of the fan 61c, and the controller 74 acquires the temperature
measured by the temperature sensor via the signal wire (not shown
in the figure). The controller 74 then controls the components
relating to the above-mentioned typical compression-type
refrigeration cycle via a signal wire (not shown in the figure) so
that the measured temperature becomes the set temperature.
[0139] As described hereinabove, in the present example, the
liquid-gas heat exchanger 61b is disposed on the upstream side of
the warm air flow, and the evaporator 61a is disposed on the
downstream side.
[0140] The cold air generated by the evaporator 61a is discharged
from the indoor air outlet 63 (after passing through the fan 61c).
In this case, as shown in FIG. 2, the indoor air unit outlet 63 is
disposed to be connected to the under-floor space. Therefore, by
contrast with the indirect outdoor air cooling system 20 shown in
FIG. 1, the integrated indirect outdoor air cooling system 50 is
disposed such that part thereof enters the under-floor space, as
shown in FIG. 2. As a result, the cold air discharged from the
indoor air outlet 63 flows into the under-floor space, flows into
the space of server setting via the under-floor space and cools the
heating elements 101. The cold air becomes warm air after cooling
the heating elements 101, and this warm air flows into the attic
space and then again flows from the indoor air unit inlet 62 into
the indoor air unit 60.
[0141] Meanwhile, in the outdoor air unit 70, the outdoor air that
has flown into the outdoor air unit 70 via the outdoor air inlet
72, first, passes through the liquid-gas heat exchanger 71b, where
heat exchange is performed between the outdoor air and liquid
(water or the like). The liquid (water of the like), is heated by
heat exchange with the warm air in the liquid-gas heat exchanger
61b. The temperature of the liquid (water or the like) is reduced
by heat exchange between the liquid (water or the like) that is
thus increased in temperature and the outdoor air. The liquid
(water or the like) reduced in temperature is supplied again by the
circulating pump 53 and the piping 51 to the liquid-gas heat
exchanger 61b side.
[0142] Meanwhile, the temperature of the outdoor air is raised by
the heat exchange with the liquid (water or the like) passing
inside the liquid-gas heat exchanger 71b. The outdoor air thus
increased in temperature then passes through the condenser 71a. The
condenser 71a further rises the temperature by radiating heat in
the above-described manner. The heated outdoor air is then
discharged from the outdoor air outlet 73.
[0143] The following effects mainly can be obtained with the
above-described integrated indirect outdoor air cooling system
50.
[0144] (a) Compact Configuration
[0145] In the conventional configuration or the first embodiment,
two devices, namely, the typical air conditioner and the indirect
outdoor air cooler, are provided, but those two devices are
integrated thereby making it possible to reduce the system. As a
result, the installation space can be reduced and the system can be
installed, for example, even when the machine room is narrow
(alternatively, the system reduced in width to a degree
unattainable in the conventional configuration can be
installed).
[0146] (b) Reduction of Construction Cost Due to Ductless
Configuration and Wall Mounting
[0147] The results are similar to those obtained in the
above-described first embodiment, and it is not necessary to
provide ducts as in the conventional configuration. The indoor air
unit and outdoor air unit are manufactured in advance, for example,
at a plant, and those units are mounted on the wall surface in the
construction process (however, the operations of making holes for
piping and hole for embedding the integrated outdoor-indoor air
unit are still required), thereby making it possible to reduce the
construction time and efforts and lower the construction cost.
[0148] (c) Size Reduction and Improvement of Manufacturability by
Stacked Configuration
[0149] In the conventional configuration or the first embodiment,
the evaporator, liquid-gas heat exchanger, and fan are present as
separate units, for example in the configuration inside the
building (those units are also manufactured individually). By
contrast, in the second embodiment, the evaporator, liquid-gas heat
exchanger, and fan are stacked and integrated to form a stack,
thereby enabling size reduction. Further, since those units are
manufactured together, rather than individually, the manufacturing
process is facilitated. In particular, additional improvement of
manufacturability can be expected by making those units
substantially identical in shape and size, as shown in FIG. 2 or
FIG. 3. The resultant configuration can be expected to be
convenient in transportation and easy to install.
[0150] (d) Reduction in Blow Energy (Blow Power) and Cost Reduction
by Using Shared Fans
[0151] In the configuration of the second embodiment, the number of
fans can be reduced by comparison with that in the conventional
configuration or the first embodiment and, therefore, the blow
energy (blow power) and cost can be reduced. For example, in the
configuration of the first embodiment shown in FIG. 1, a total of
four fans, namely, the fan 11a, fan 12b, fan 32, and fan 42, are
provided. By contrast, the configuration of the second embodiment
shown in FIGS. 2 and 3 requires only two fans, namely, the fans
71c. In other words, the number of fans can be reduced by half.
Therefore, the purchasing cost of the fans can be reduced by half.
Electric power is required to operate the fans, but this power is
lower when two fans are used, than when tour fans are
installed.
[0152] The air conditioning system of the third embodiment will be
explained below.
[0153] The air conditioning system of the third embodiment resolves
the above-described main problem. Thus, the air conditioning system
is provided in which the outdoor air can be used for cooling the
interior space even when the outdoor air temperature is high.
[0154] FIG. 4 shows the configuration of the air conditioning
system (variation 1) of the third embodiment.
[0155] FIGS. 5A and 5B show the configuration of the air
conditioning system (variation 2) of the third embodiment.
[0156] FIG. 6 shows the operation model of the air conditioning
system of the third embodiment.
[0157] The air conditioning system of the third embodiment uses the
outdoor air to cool the interior space, as in the above-described
indirect outdoor air cooling system, and is therefore sometimes
also called "outdoor-air-using air conditioning system".
[0158] This system will be initially explained hereinabove with
reference to FIG. 4.
[0159] The air conditioning system (variation 1) of the third
embodiment shown in the figure is constituted by an outdoor air
unit 80 provided outside the building and an indoor air unit 90
provided inside the building, with the wall 1 as a boundary, in the
same manner as, for example, in the first and second embodiments.
Such embodiment is, however, not limited to this example. For
example, the below-described configuration shown in FIG. 10 may be
also used.
[0160] In FIG. 4, the outdoor air unit 80 has a stack 81 and is
also provided with part of a piping 96 where the second refrigerant
is circulated. Specific examples of the second refrigerant include
liquid such as "water" and Freon. The stack 81 has a liquid-gas
heat exchanger 81b, which is an example of the configuration for
performing heat exchange between the second refrigerant and the
outdoor air, and a fan 81a. Those components are stacked and
integrated as shown in the figure. The shape and structure of such
a stack and manufacturing method thereof have already been
explained in relation to the stacks 61 and 71 in the second
embodiment, and the explanation thereof is herein omitted.
[0161] The liquid-gas heat exchanger 81b and fan 81a are not
necessarily configured as a stack. Although they are shown in a
simplified manner in FIG. 4, holes corresponding to the outdoor air
inlet 72 and outdoor air outlet 73 are actually provided in the
housing of the outdoor air unit 80, in the same manner as in the
above-described outdoor air unit 70.
[0162] The installation location and installation method (including
the manufacturing operations at the plant or the like) of the
outdoor air unit 80 may be substantially the same as those of the
outdoor air units 40 and 70, but such embodiment is not being
limited to this. The same applies to the indoor air unit 90 shown
in the figure. Thus, the housing of the indoor air unit 90 is also
provided with holes (not shown in the figure) corresponding to the
indoor air unit inlet 62 and indoor air unit outlet 63. The
installation location and installation method (including the
manufacturing operations at the plant or the like) of the indoor
air unit 90 may be substantially the same as those of the outdoor
air units 30 and 60, but the embodiment is not limited to this.
[0163] The indoor air unit 90 has the stack 91 and also has part of
the piping 96 where the second refrigerant (for example, the
cooling liquid such as "water") circulates, the refrigerant piping
95 (in the figure, the entire refrigerant piping is shown, but only
part thereof may be included) where the first refrigerant (for
example, Freon) circulates, a pump 94 provided along the way in the
piping 96, a compressor 92 and an expansion valve 93 provided along
the way in the refrigerant piping 95. This is only an example, and
the system is not limited to this example. For example, one, two or
all of the pump 94, compressor 92, and expansion valve 93 may be
provided at the outdoor air unit 80 side or outside the indoor air
unit 90 (for example, inside the building). Where either of the
compressor 92 or the expansion valve 93 is provided at the outdoor
air unit 80 side, part of the refrigerant piping 95 is also
installed at the outdoor air unit 80 side.
[0164] The above-mentioned stack 91 of the indoor air unit 90 has a
fan 91a, a condenser 91b, a liquid-gas heat exchanger 91c, which is
an example of the configuration for performing heat exchange
between the second refrigerant and the indoor air, and an
evaporator 91d and is configured by stacking and integrating those
components as shown in the figure. It is not necessary that all of
the fan 91a, condenser 91b, liquid-gas heat exchanger 91c, and
evaporator 91d be stacked. For example, the fan 91a may be provided
separately. Alternatively, all of the components may be provided
separately. However, as already explained in the second embodiment,
the stacked configuration offers significant merits.
[0165] The mutual arrangement of the condenser 91b, liquid-gas heat
exchanger 91c, and evaporator 91d in the indoor air unit 90 is
specified as described hereinbelow, regardless of whether or not
the stacked configuration is used.
[0166] Thus, the components are arranged in the order of condenser
91b.fwdarw.liquid-gas heat exchanger 91c.fwdarw.evaporator 91d from
the upstream side of the flow of the air (indoor air) passing
through in the indoor air unit 90. In other words, the condenser
91b is disposed on the most upstream side of the air (indoor air)
flow, the liquid-gas heat exchanger 91c is disposed next thereto,
and the evaporator 91d is disposed on the most downstream side. In
the case where the air (indoor air) flows as shown by a dot-dash
arrow in the figure, the components are arranged in the order of
condenser 91b.fwdarw.liquid-gas heat exchanger
91c.fwdarw.evaporator 91d from the left side in the figure, for
example, as shown in the figure.
[0167] By contrast, where the air flow formed by the fan 91a is
reversed, as shown in FIG. 8, the components are arranged in the
order of evaporator 91d.fwdarw.liquid-gas heat exchanger
91c.fwdarw.condenser 91b from the left side in the figure, as in a
stack 91' shown in FIG. 8. In other words, the components are
arranged as condenser 91b.fwdarw.liquid-gas heat exchanger 91c-4
evaporator 91d in the order of description from the upstream side
of the air (indoor air) flow passing through in the indoor air unit
90, in the same manner as shown in FIG. 4. Even if the arrangement
is changed, as shown in FIG. 8, the flow sequence of the first
refrigerant does not change. Thus, the first refrigerant circulates
in the following sequence: "evaporator 91d.fwdarw.compressor
92.fwdarw.condenser 91b.fwdarw.expansion valve 93.fwdarw.evaporator
91d".
[0168] In the case of the environment such as shown in FIG. 14, 1,
or 2, it is desirable that the air flow in the same manner as in
the indoor air unit 60 shown in FIGS. 2 and 3. In other words, it
is desirable that the air flow as shown in FIG. 8, rather than as
shown in FIG. 4 (it goes without saying, that the configuration in
this case is such as shown in FIG. 8). The reason therefor has
already been explained in the second embodiment.
[0169] Thus, for example, in FIG. 2, the outdoor air unit 80 and
the indoor air unit 90 can be installed instead of the outdoor air
unit 70 and the indoor air unit 60. In this case, as shown in FIG.
4, the cold air generated by the evaporator 91d is delivered from
the hole (not shown in the figure) on the upper side of the housing
of the indoor air unit 90. However, as shown in FIG. 2, the
destination of the cold air is the under-floor space on the lower
side. Therefore, the configuration is preferred in which, as shown
in FIG. 8, the cold air generated by the evaporator 91d is
delivered from the hole (not shown in the figure) on the lower side
of the housing of the indoor air unit 90. The reasons therefor are
also associated with the inflow of the return air (warm air) from
the attic space (they have already been explained and are omitted
herein).
[0170] The explanation now returns to FIG. 4.
[0171] As shown in the figure, the evaporator 91d, condenser 91b,
expansion valve 93, and compressor 92 are connected to the
refrigerant piping 95. The first refrigerant circulates in the
evaporator 91d, condenser 91b, expansion valve 93, and compressor
92 via the refrigerant piping 95. Thus, the first refrigerant
circulates in the following typical compression-type refrigeration
cycle (vapor compression-type refrigeration cycle or the like):
"evaporator 91d compressor 92.fwdarw.condenser 91b.fwdarw.expansion
valve 93.fwdarw.evaporator 91d". As in the conventional
configuration, when the first refrigerant is evaporated in the
evaporator 91d, the heat is drawn from the surroundings, and the
surroundings (indoor air) are thus cooled. The heat that has been
drawn in is radiated to the surroundings in the condenser 91b. The
expansion valve 93 and the compressor 92 function in the same
manner as in the conventional configuration and are not explained
herein.
[0172] As shown in FIG. 14, 1, 2, or 3, the condenser is usually
disposed on the exterior side (outside the building) and radiates
the heat to the outdoor air. Meanwhile, as shown in FIG. 4, in the
third embodiment, the condenser is provided on the interior side
(for example, inside the indoor air unit 90, but the embodiment is
not limited to this arrangement). This is one of the specific
features of the third embodiment. It will be explained hereinbelow
in greater detail.
[0173] As mentioned hereinabove, the indoor air serving as the
return air (warm air) flowing from the interior space (the attic
space) into the indoor air unit 90, first, passes through the
condenser 91b, then passes through the liquid-gas heat exchanger
91c, and finally passes through the evaporator 91d. When passing
through the condenser 91b, the return air is heated by the heat
radiated from the condenser 91b, and when the return air then
passes through the liquid-gas heat exchanger 91c, the temperature
thereof drops due to heat exchange with the second refrigerant
(water or the like). The return air then passes through the
evaporator 91d where it is cooled and becomes cold air. The cold
air is supplied, for example, through the under-floor space, for
example, into the server room which the object of cooling.
[0174] In this configuration, the liquid-gas heat exchanger 81b and
the liquid-gas heat exchanger 91c are substantially the same as the
liquid-gas heat exchangers 61b and 71b of the second embodiment and
connected to each other by the piping 96. The second refrigerant
(water or the like) provided inside the piping 96 is circulated by
the pump 94 inside the liquid-gas heat exchangers 81b and 91c and
the piping 96. Further, the liquid-gas heat exchangers 81b and 91c
may be considered substantially identical to the liquid-gas heat
exchangers 31 and 41 or the liquid-gas heat exchangers 61b and
71b.
[0175] The second refrigerant (water or the like) passes through in
the liquid-gas heat exchanger 91c, and the indoor air (warm air)
also passes therethrough. As a result, heat exchange is performed
between the second refrigerant (water or the like) and warm air
inside the liquid-gas heat exchanger 91c and, essentially, the warm
air is cooled (the heat of the warm air moves to the liquid) and
the temperature of the warm air decreases. In the conventional
configuration, this, however, depends on the temperature of the
outer air and warm air and does not guarantee that the temperature
of the warm air drops.
[0176] However, in the configuration of the third embodiment shown
in FIG. 4, the temperature of the indoor air (warm air) rises since
the radiation of heat by the condenser 91b takes place before (on
the upstream side of) the liquid-gas heat exchanger 91c. For
example, even if the temperature of the return air (warm air) from
the interior space is 30.degree. C. and the outdoor air temperature
is 35.degree. C., where the temperature of the indoor air that has
passed through the condenser 91b becomes 45.degree. C., the
temperature of the indoor air decreases in the liquid-gas heat
exchanger 91c (for example, 45.degree. C..fwdarw.36.degree. C.)
[0177] In other words, with the conventional configuration, even in
the environment in which the outdoor-air-using cooling (indirect
outdoor air cooling) is functionally imperfect, the cooling still
functions. Further, the cooling efficiency of the indoor air
increases with the increase in the difference in temperature
between the indoor air and outdoor air.
[0178] In the configuration described herein, for example, the
indoor air cooling can be substantially performed by the outdoor
air even in the environment with a high outdoor air temperature,
and 36.degree. C. is higher than the natural indoor air temperature
(30.degree. C.). However, the cooling of the first refrigerant in
the condenser 91b uses the outdoor air with a temperature of
35.degree. C. in the conventional configuration, but uses the
indoor air with a temperature of 30.degree. C. in the present
example. In other words, where the outdoor air temperature is
higher than the temperature of the return air (indoor air), the
configuration of the third embodiment shown in FIG. 4 demonstrates
a higher effect of cooling the first refrigerant in the condenser
91b than the conventional configuration.
[0179] As a result, where the outdoor air temperature is so high,
power consumption is reduced (energy saving effect is high) by
comparison with the conventional configuration, as demonstrated by
simulation below. This will be described below in greater
detail.
[0180] The configuration shown in FIG. 4 or in the below-described
FIG. 8 has the following merits, for example, over that shown in
FIG. 3.
[0181] Thus, in the configuration shown in FIGS. 4 and 8, the
condenser is installed on the interior side (indoor air unit). The
resultant merits are that there are locations where the piping
length is reduced (the piping 96 is shorter than the refrigerant
piping 52) and the number of through holes in the wall 1 is reduced
("4".fwdarw."2"). Another merit of the configuration shown in FIGS.
4 and 8 over those shown in the below-described FIGS. 5A, 5B, 9,
11, and 12 is that the number of through holes in the wall 1 can be
reduced ("5".fwdarw."2").
[0182] The configuration example of the air conditioning system
(variation 2) of the third embodiment will be explained below with
reference to FIGS. 5A and 5B. FIG. 5A shows the first example, and
FIG. 5B shows the second example.
[0183] The configurations shown in FIGS. 5A and 5B are based on the
configuration shown in FIG. 4. In those configurations, a
compressor is provided also on the outdoor air unit side and the
switching control is performed by using a three-way valve 112
(switching device shown in the figure). As a result, operations
substantially similar to those of second embodiment (FIG. 3) can be
also performed.
[0184] The space which is the object of cooling with the air
conditioning system (variation 1) (variation 2) shown in FIGS. 4,
5A, and 5B is assumed, for example, to be the same as in FIG. 1 or
2. Thus, the interior space that is the object of cooling is, for
example, the server room having installed therein a large number of
server racks 102 carrying heating elements 101 such as server
devices (computer devices). The cold air is delivered into the
under-floor space, the cold air is supplied into the space of
server setting, and the heating elements 101 are cooled by the cold
air. As a result, the cold air becomes warm air, and the warm air
flows into the attic space. The return air (warm air) from the
attic space flows into the indoor air unit 90 shown in FIG. 4 or an
indoor air unit 120 shown in FIGS. 5A and 5B, and the cold air is
generated in those indoor air units and delivered into the
under-floor space.
[0185] First, the configuration shown in FIG. 5A will be explained
below.
[0186] The air conditioning system (variation 2) of the third
embodiment shown in FIG. 5A is constituted by the indoor air unit
120 and an outdoor air unit 110. The housings,
manufacture/installation methods, and mutual arrangements of the
indoor and outdoor air units for the indoor air unit 120 and the
outdoor air unit 110 may be substantially the same as for the
indoor air unit 60 and the outdoor air unit 70 and are not
explained in detail herein.
[0187] Initially, the indoor air unit 120 will be explained
below.
[0188] The indoor air unit 120 has the stack 121. This stack 121
has a fan 121a, a condenser 121b, a liquid-gas heat exchanger 121c,
and an evaporator 121d and configured by stacking the integrating
those components as shown in the figure.
[0189] The stack 121 is identical to the stack 91 shown in FIG. 4.
Therefore, the conditions same as those of the stack 91 are
applied. Thus, the components are disposed as condenser
121b.fwdarw.liquid-gas heat exchanger 121c.fwdarw.evaporator 121d
in the order of description from the upstream side of the flow of
air (indoor air) passing through in the indoor air unit 120.
[0190] In the configuration in which the evaporator, liquid-gas
heat exchanger, condenser, and fan are integrated as a stack in the
above-described manner, significant merits such as described
hereinabove can be obtained, but the embodiment is not limited to
such configuration. For example, only any two or more of those four
structural components may be stacked, or all four structural
components may be provided separately (however, in this case, the
components are also arranged as condenser.fwdarw.liquid-gas heat
exchanger.fwdarw.evaporator in the order of description from the
upstream side of the indoor air flow, as explained with reference
to FIG. 4).
[0191] In the third embodiment, holes such as an indoor air inlet
128 and an indoor air outlet 127 shown in the figure are provided
in the housing of the indoor air unit 120, in the same manner as in
the second embodiment (those holes are not shown in FIG. 4). In the
present example, a fan 121a forms the air flow shown by a
one-dot-dash arrow in the figure. Thus, the fan 121a creates the
air flow (shown by a one-dot-dash arrow in the figure) such that
the warm air of the attic space flows from the indoor air inlet 128
into the indoor air unit 120, passes through in the indoor air unit
120 (in particular, the stack 121), and becomes cold air which is
discharged from the indoor air outlet 127. The cold air discharged
from the indoor air outlet 127 flows into the server room through
the under-floor space.
[0192] The fan 121a may also form the air flow (the flow in the
direction opposite to that of the flow shown by the one-dot-dash
arrow in the figure) such that the hole serving as the indoor air
outlet 127 in the figure is the indoor air inlet and the hole
serving as the indoor air inlet 128 in the figure is the indoor air
outlet, in the same manner as shown in FIGS. 2 and 3. Such
configuration example is shown in FIG. 9. As shown in FIG. 9, an
indoor air inlet 127' is provided on the upper side of the housing,
and the indoor air outlet 128' is provided at the lower side of the
housing.
[0193] Further, in this case, the configuration of the stack 121 is
changed as shown in FIG. 9. Thus, as described hereinabove, the
components are arranged as condenser.fwdarw.liquid-gas heat
exchanger.fwdarw.evaporator in the order of description from the
upstream side of the flow of air (indoor air) inside the indoor air
unit. Therefore, the condenser 121h and the evaporator 121d shown
in FIG. 5A are exchanged one for another. Thus, the stack 121'
shown in FIG. 9 is configured.
[0194] As shown in the figure, in the stack 121', the condenser
121b, liquid-gas heat exchanger 121c, and evaporator 121d are
disposed in the order of description from the right side in the
figure. The indoor air flow formed by the fan 121a is such that the
indoor air flows into the housing from the indoor air inlet 127'
and is discharged from the indoor air outlet 128' as shown by a
one-dot-dash arrow in FIG. 9. Therefore, the components are
arranged as condenser 121b.fwdarw.liquid-gas heat exchanger
121c.fwdarw.evaporator 121d in the order of description from the
upstream side of such air flow.
[0195] The explanation now returns to FIG. 5A.
[0196] The outdoor air unit 110 has the stack 111.
[0197] The stack 111 has a fan 111a, a liquid-gas heat exchanger
111b, and a condenser 111c and is configured by stacking and
integrating those components as shown in the figure. It is not
necessary that those three structural components be all stacked.
The housing of the outdoor air unit 110 (similarly to the outdoor
air unit 70) is provided with holes such as an outdoor air inlet
114 and an outdoor air outlet 115, which are shown in a simplified
manner in FIG. 4. The fan 111a creates the air flow (shown by a
dot-dash line in the figure) such that the exterior air (outdoor
air) flows from the outdoor air inlet 114 into the outdoor air unit
110, passes through the stack 111, and is then discharged from the
outdoor air outlet 115.
[0198] The stack 111 may by itself be identical to the stack 71.
Similarly to the stack 71, the stack 111 is configured to be
provided with the liquid-gas heat exchanger 111b on the upstream
side of the air flow (shown by a dot-dash arrow in the figure) such
as explained hereinabove, and with the condenser 111c on the
downstream side. The same configuration is used in the case where
no stack is configured.
[0199] An expansion valve 123 and a compressor 113 are each
provided in either of the outdoor air unit 110 and the indoor air
unit 120. In the example shown in the figure, the expansion valve
123 is provided in the indoor air unit 120, and the compressor 113
is provided in the outdoor air unit 110, but the embodiment is not
limited to this example (the modification has already been
explained in the second embodiment, and the explanation thereof is
herein omitted).
[0200] Further, as shown in the figure, the evaporator 121d,
expansion valve 123, and compressor 113 are connected to a
refrigerant piping 125. In addition a three-way valve 112, which is
an example of a switching device, is provided in the refrigerant
piping 125 along the way thereof, and the refrigerant piping is
branched from the three-way valve 112 into a refrigerant piping
125a and a refrigerant piping 125b, which are shown in the figure.
The refrigerant piping 125a is connected to the condenser 121b of
the stack 121. The refrigerant piping 125b is connected to the
condenser 111c of the stack 111 and merges at the distal end
thereof with the refrigerant piping 125a. As a result, by
performing valve opening/closing switching of the three-way valve
112, it is possible to cause the first refrigerant to flow in
either of the refrigerant piping 125a and the refrigerant piping
125b. In other words, the first refrigerant can flow into either of
the condenser 111c and the condenser 121b.
[0201] Thus, the first refrigerant circulates in the evaporator
121d, condenser 111c or condenser 121b, expansion valve 123, and
compressor 113 through the refrigerant piping 125 (including the
refrigerant piping 125a and the refrigerant piping 125b). Thus, the
first refrigerant circulates in the following typical
compression-type refrigeration cycle (vapor compression-type
refrigeration cycle or the like): "evaporator
121d.fwdarw.compressor 113.fwdarw.condenser 111c or condenser
121b.fwdarw.expansion valve 123.fwdarw.evaporator 121d".
[0202] In the same manner as in the conventional configuration,
when the first refrigerant is evaporated in the evaporator 121d,
the heat is drawn from the surroundings, and the surroundings are
thereby cooled. The heat that has been drawn in is radiated into
the surroundings in the condenser 111c or the condenser 121b. The
expansion valve 123 and the compressor 113 also function in the
same manner as in the conventional configuration and the
explanation thereof is herein omitted.
[0203] The refrigerant switching control performed by the three-way
valve 112 is determined, for example, by the outdoor air
temperature or indoor air temperature. Alternatively, the control
may be determined on the basis of the amount of consumed power.
[0204] Thus, the effect demonstrated by the configuration shown in
FIG. 4 is greatly superior to that of the conventional air
conditioning system, in particular when the outdoor air temperature
is high (for example, equal to or higher than 30.degree. C.), but
when the outdoor air temperature is low, the reverse effect can
sometimes be obtained.
[0205] Accordingly, for example, the controller 130 shown in the
figure performs the valve opening/closing control of the three-way
valve 112 and causes the first refrigerant to flow into the
refrigerant piping 125a (condenser 121b), for example, when the
outdoor air temperature is equal to or higher than a predetermined
temperature, or when "outdoor air temperature>indoor air
temperature" and the difference in temperature between the outdoor
air and the indoor air is equal to or greater than a predetermined
value. The effect produced by the operation in this case is
substantially the same as that illustrated by FIG. 4. Thus, where a
state is assumed in which the first refrigerant flows into the
piping 125a (condenser 121b), the heat is radiated from the
condenser 121b into the indoor air and, therefore, the stack 121
functions in a substantially the same manner as the stack 91 (the
indoor air temperature, as referred to herein, is the temperature
of the return air from the attic space).
[0206] Thus, the return air (warm air) flowing from the interior
space (the attic space thereof) into the indoor air unit 120 via
the indoor air inlet 128 initially passes through the condenser
121b, then passes through the liquid-gas heat exchanger 121c, and
finally passes through the evaporator 121d. When the return air
passes through the condenser 121b, the temperature of the return
air rises due to heat radiation from the condenser 121b. When the
return air thereafter passes through the liquid-gas heat exchanger
121c, the temperature of the return air is decreased by heat
exchange with the second refrigerant (water or the like). When the
return air eventually passes through the evaporator 121d, the
return air is cooled and becomes cold air.
[0207] It is possible to measure the amount of consumed power
before and after performing the valve opening/closing control of
the three-way valve 112, allow the system to stay as is if the
amount of consumed powder has reduced and again perform the valve
opening/closing control of the three-way valve 112 and return to
the original state (the state in which the first refrigerant flows
into the refrigerant piping 125b (condenser 111c)) if the amount of
consumed powder has increased. Alternatively, it is possible to
perform the valve opening/closing control of the three-way valve
112 and return to the original state (the state in which the first
refrigerant flows into the refrigerant piping 125b (condenser
111c)) when, for example, the outdoor air temperature became less
than a predetermined temperature after the switching, or when
"outdoor air temperature.ltoreq.indoor air temperature" or "outdoor
air temperature>indoor air temperature", but the difference in
temperature between the outdoor air and indoor air is less than a
predetermined value.
[0208] For example, when the outdoor air temperature is less than a
predetermined temperature, the first refrigerant is caused to flow
into the refrigerant piping 125b (condenser 111c) by performing the
valve opening/closing control of the three-way valve 112. The
operations in this case are the same as illustrated by FIGS. 2 and
3.
[0209] Thus, the return air (warm air) flowing from the interior
space (the attic space thereof) through the indoor air inlet 128
into the indoor air unit 120 passes, without any particular
changes, through the condenser 121b. The temperature of the return
air decreases due to heat exchange with the second refrigerant
(water or the like) when the return air then passes through the
liquid-gas heat exchanger 121c, and finally the return air is
cooled when passing through the evaporator 121d and becomes cold
air. Meanwhile, the heat drawn from the surroundings by the
evaporator 121d is radiated to the outdoor air in the condenser
111c. The second refrigerant is circulated by the circulating pump
124 inside the piping 126. The piping 126 is connected to the
liquid-gas heat exchangers 111b and 121c in the same manner as the
piping 51.
[0210] Such valve opening/closing control of the three-way valve
112 is performed, for example, by the controller 130 shown in the
figure, but the detailed explanation thereof is herein omitted. The
controller 130 is a control device of the entire present air
conditioning system that has a CPU/MPU and a memory and performs
the control of adjusting the temperature of the cold air, for
example, by inputting temperature data from a temperature sensor
(not shown in the figure). The controller 130 may be installed at
any location.
[0211] In the example shown in FIG. 5A, check valves 122a and 122b
are provided, as shown in the figure, in order to prevent the first
refrigerant that has flown into the refrigerant piping 125a from
flowing into the refrigerant piping 125b (and, conversely, to
prevent the first refrigerant that has flown into the refrigerant
piping 125b from flowing into the refrigerant piping 125a). Thus,
as shown in the figure, the refrigerant piping 125a and the
refrigerant piping 125b, which are the branched pieces of the
refrigerant piping 125, merge in a merging point R shown in the
figure and again become a single refrigerant piping 125. In the
refrigerant piping 125a, as shown in the figure, the check valve
122a is provided before the merging point R. In the refrigerant
piping 125b, the check valve 122b is likewise provided before the
merging point R.
[0212] The configuration shown in FIG. 4 will be explained below
using FIG. 5A. Since the condenser 111c is not present, the
three-way valve 112, refrigerant piping 125b, and check valves 122a
and 122b are also not present (the refrigerant piping 125a can be
considered as the refrigerant piping 125).
[0213] Conversely, where the configuration shown in FIG. 5A is
explained on the basis of the configuration shown in FIG. 4,
initially, the condenser 111c is added, the refrigerant piping 125
is branched along the way, and the refrigerant piping 125b, which
is obtained as a branched piping, is connected to the condenser
111c. Then, the three-way valve 112, which is an example of a
switching device, is provided in the branching point of the
refrigerant piping 125, and the first refrigerant is caused by the
switching device to flow in either of the condenser 121b and the
condenser 111c. The abovementioned check valves 122a and 122b are
then also added.
[0214] The configuration example shown in FIG. 5B will be explained
below.
[0215] The configuration shown in FIG. 5B is substantially
identical to the configuration shown in FIG. 5A and only partially
different therefrom. Accordingly, only those features by which the
configuration shown in FIG. 5B differs from that shown in FIG. 5A
will be explained below, and the explanation of the configuration
substantially identical to that shown in FIG. 5A will be
omitted.
[0216] In the configuration shown in FIG. 5B, a three-way valve
112' shown in the figure is provided instead of the three-way valve
112 shown in FIG. 5A. The three-way valve 112 shown in FIG. 5A is
provided before (inflow side) the condenser 111c. In contrast, the
three-way valve 112' shown in FIG. 5B is provided after (outflow
side) the condenser 111c. The refrigerant piping 125 branches into
the refrigerant piping 125a and the refrigerant piping 125b form
the three-way valve 112' in a substantially the same manner as
shown in FIG. 5A. The refrigerant piping 125b is connected to the
expansion valve 123, and the refrigerant piping 125a is connected
to the condenser 121b in a substantially the same manner as shown
in FIG. 5A.
[0217] In the configuration shown in FIG. 5A, the refrigerant is
caused to flow in either of the condenser 111c and the condenser
121b by the valve switching control of the three-way valve 112. In
contrast, in the configuration shown in FIG. 5B, the refrigerant
necessarily flows in the condenser 111c, and whether or not to
cause the refrigerant to flow in the condenser 121b is controlled
by switching the three-way valve 112'.
[0218] Since the temperature of the refrigerant at the outlet side
of the compressor 113 is usually higher than the outdoor air
temperature, the refrigerant temperature can be expected to be
decreased by using the configuration in which the refrigerant
necessarily flows in the condenser 111c. Further, when "outdoor air
temperature>indoor air temperature", the refrigerant is caused
to flow in the refrigerant piping 125a (the refrigerant is also
caused to flow in the condenser 121b) by performing the switching
control of the three-way valve 112'. As a result, the refrigerant
temperature can be temporarily decreases in the condenser 111c and
then further lowered close to the indoor air temperature in the
condenser 121b.
[0219] The outdoor air temperature has the same meaning as the
temperature of the outdoor air.
[0220] With the configuration shown in FIG. 5B, the amount of heat
exchange between the refrigerant and the indoor air in the
condenser 121b is decreased. Therefore, the condenser 121b can be
reduced in size. Further, since the amount of heat that should be
taken out by the heat exchanger 121c is reduced, the efficiency can
be expected to increase (for example, the blow amount of the fan
111a is decreased or the flow rate of the refrigerant circulated by
the pump 124 is reduced).
[0221] The configuration shown in FIG. 5B can be also explained in
the following manner.
[0222] Thus, the outdoor air unit 110 is also provided with the
condenser 111c, the refrigerant piping 125 is connected to the
condenser 111c, the refrigerant piping 125 is branched at the
refrigerant outlet side of the condenser 111c, and a switching
device (three-way valve 112') is provided in the branching point.
The switching device switches the circulation to either one of the
first route in which the first refrigerant is circulated in the
condenser 121b inside the indoor air unit 120 and then circulated
in the expansion valve 123 and the second route in which the first
refrigerant is circulated in the expansion valve 123, without
circulating in the condenser 121b inside the indoor air unit 120.
The outer switching control performed by the switching device is
executed, for example, by the controller 130.
[0223] FIG. 6 shows the operation model of the air conditioning
system of the third embodiment and the simulation results.
[0224] First, the simulation operation model shown in FIG. 6A will
be explained.
[0225] The explanation below relates to the configuration shown in
FIG. 4, but the same applies to the configurations shown in FIGS.
5A and 5B (when they are operated in the same manner as the
configuration shown in FIG. 4).
[0226] In FIG. 6, a thick-line arrow shows the flow of air (indoor
air). The components arranged along the flow of air (indoor air),
that is, the components through which the indoor air flows, include
a heating element 140, a condenser 141, a liquid-gas heat exchanger
142, and an evaporator 143 shown in the figure.
[0227] The heating element 140 corresponds to the abovementioned
heating element 101 (server device or the like) located in the
interior space of the cooling object. The condenser 141 corresponds
to the condenser 91b, the liquid-gas heat exchanger 142 corresponds
to the liquid-gas heat exchanger 91c inside the indoor air unit 90,
and the evaporator 143 corresponds to the evaporator 91d. The
compressor 144 shown in the figure corresponds to the compressor
92, and the expansion valve 145 shown in the figure corresponds to
the expansion valve 93.
[0228] The thin-line arrows shown in the figure and connecting
those condenser 141, evaporator 143, compressor 144, and expansion
valve 145 show the flow of the first refrigerant. Thus, the first
refrigerant circulates in the following compression-type
refrigeration cycle (vapor compression-type refrigeration cycle or
the like): "evaporator 143.fwdarw.compressor 144.fwdarw.condenser
141.fwdarw.expansion valve 145.fwdarw.evaporator 143".
[0229] The pump 146 shown in the figure corresponds to the pump 94,
and the liquid-gas heat exchanger 147 shown in the figure
corresponds to the liquid-gas heat exchanger 81b on the outdoor air
unit 80 side. The thin-line arrows shown in the figure and
connecting those pump 116, liquid-gas heat exchanger 147, and
liquid-gas heat exchanger 142 show the flow of the second
refrigerant (water or the like). As a result, in the liquid-gas
heat exchanger 142, the second refrigerant exchanges heat with the
indoor air, whereas in the liquid-gas heat exchanger 147, the
second refrigerant exchanges heat with the outdoor air. Therefore,
when the outdoor air temperature is low, an indirect outdoor air
cooling function is realized such that the indoor air is indirectly
cooled by the outdoor air through the second refrigerant.
[0230] FIG. 6A shows an example of the temperatures of the indoor
air and the first refrigerant at each stage of the abovementioned
cycle. This is obviously only one example. Further, this example
shows the temperatures that are ideal for simulation and does not
reflect actual results. For example, although the temperature of
the first refrigerant drops significantly in the condenser 141, it
does not decrease to reach the temperature (32.degree. C.) equal to
the indoor air temperature, as shown in the figure, and has a
somewhat higher value (33.degree. C.)
[0231] The explanation is started with the evaporator 143. In the
example shown in the figure, the indoor air is cooled in the
evaporator 143 and becomes cold air with a temperature of
18.degree. C. The heating element 140, which is a server device or
the like, is cooled by the cold air, and the indoor air becomes
warm air with a temperature of 32.degree. C. The warm air with a
temperature of 32.degree. C. passes through the condenser 141.
[0232] The first refrigerant with a high temperature (66.degree.
C.) that is generated by the compressor 144 flows into the
condenser 141, and the heat thereof is radiated to the
surroundings. In the condenser 141, the first refrigerant with a
high temperature (66.degree. C.) is cooled by the warm air with a
temperature of 32.degree. C. As a result, after the condenser 141,
the temperature of the first refrigerant decreases to 32.degree.
C., but the temperature of the warm air (indoor air) rises to
55.degree. C.
[0233] The first refrigerant with a temperature of 32.degree. C.
becomes the first refrigerant with a temperature of 10.degree. C.
in the expansion valve 145 of the next stage and flows into the
evaporator 143. As a result, the evaporator 143 cools the indoor
air in the above-described manner and generates cold air with a
temperature of 18.degree. C.
[0234] Meanwhile, the warm air with a temperature of 55.degree. C.
undergoes heat exchange with the second refrigerant when passing
through the liquid-gas heat exchanger 142. As a result, the
temperature of this warm air drops to 36.degree. C. The warm air
with a temperature of 36.degree. C. passes through the evaporator
143 and becomes cold air with a temperature of 18.degree. C. as
described hereinabove.
[0235] As described hereinabove, the return air from the interior
space has a temperature of 32.degree. C., whereas the warm air
flowing into the evaporator 143 has a temperature of 36.degree. C.
Thus, although the indirect outdoor air cooling function is used,
the temperature, conversely, rises.
[0236] However, with the indirect outdoor air cooling function, the
warm air with a temperature of 55.degree. C. is cooled to become
warm air with a temperature of 36.degree. C., and the cooling
function is served. Furthermore, since the difference in the
temperature is large, the efficiency of cooling the warm air
(indoor air) is superior. This is because even in a state with a
very high outdoor air temperature (for example, 36.degree. C.), the
warm air temperature is much lower than 55.degree. C. Where the
warm air passing through the liquid-gas heat exchanger 142 becomes
the return air with a temperature of 32.degree. C., when the
outdoor air temperature is 36.degree. C., the temperature of the
return air does not decrease, or it is even possible that this
temperature will increase. Meanwhile, in the third embodiment, it
is highly probable that the indirect outdoor air cooling will
function even when the outdoor air temperature is very high.
[0237] In this case, the indoor air assumes a high temperature of
55.degree. C., as mentioned hereinabove, because the condenser 141
is provided on the indoor air unit side (interior side) and the
indoor air is caused to pass therethrough. As shown in FIG. 14 and
FIGS. 1 to 3, the condenser is usually provided on the exterior
side to radiate heat to the outdoor air. With such a configuration,
no problem is encountered when the outdoor air temperature is low,
and the first refrigerant is sufficiently cooled by the outdoor air
in the condenser.
[0238] However, in a state with a very high outdoor air temperature
(for example, 36.degree. C.), the first refrigerant is not
sufficiently cooled by the outdoor air in the condenser, and where
the room temperature is to be maintained at a set value in this
case, power consumption rises. By contrast, in the air conditioning
system of the third embodiment, the first refrigerant is cooled in
the condenser 141, as mentioned hereinabove, by the indoor air with
a temperature of 32.degree. C. that is lower than the outdoor air
temperature. As a result, the temperature of the first refrigerant
can be reduced with respect to that of the outdoor air and power
consumption is decreased.
[0239] FIG. 6B shows the simulation results relating to the
reduction in power consumption.
[0240] In the graph shown in FIG. 6B, the outdoor air temperature
(.degree. C.) is plotted against the abscissa, and the consumed
power (kW) is plotted against the ordinate.
[0241] Data represented by triangles (.DELTA.) in the graph
indicate the power consumed by the indirect outdoor air cooling
function (mainly the power consumed by the fans and the pump 146),
data represented by rhombs (.diamond.) indicate the power consumed
by the refrigeration cycle (mainly the power consumed by the
compressor 144), and data represented by circles (.smallcircle.)
indicate the total power consumption (power consumption of the
entire system). Among those symbols, the hollow ones (hollow
triangles .DELTA., hollow rhombs .diamond., and hollow circles
.smallcircle.) represent data corresponding to the conventional air
conditioning system, and the full ones (full triangles
.tangle-solidup., full rhombs .diamond-solid., and full circles )
represent data corresponding to the air conditioning system of the
third embodiment. The conventional air conditioning system is, for
example, the air conditioning system shown in FIG. 14, but the
embodiment is not limited to this, and it may also be the air
conditioning system of the first embodiment or the second
embodiment.
[0242] As shown in the figure, where the outdoor air temperature is
comparatively low, the total power consumption of the conventional
air conditioning system is not substantially different from that of
the present air conditioning system (air conditioning system of the
third embodiment).
[0243] However, where the outdoor air temperature becomes higher
than a certain level (for example, a level of above 30.degree. C.
can be selected as a criterion), the indirect outdoor air cooling
essentially does not function in the conventional air conditioning
system and, therefore, the fans and the pump 146 are stopped,
thereby reducing to zero the power consumption (hollow triangles
.DELTA.) relating to the indirect outdoor air cooling function, as
shown in the figure. Meanwhile, in the present air conditioning
system, since the indoor air is at a very high temperature
(55.degree. C. or the like) as mentioned hereinabove, even when the
outdoor air temperature exceeds 30.degree. C., and even when it
then exceeds 35.degree. C., the indirect outdoor air cooling
functions, the fans and the pump 146 are not stopped and power
consumption is at a constant level (full triangles
.tangle-solidup.), as shown in the figure.
[0244] In the conventional air conditioning system, in the range of
outdoor air temperature (referred to hereinbelow as a
high-temperature range) in which the power consumption (hollow
triangles .tangle-solidup.) relating to the indirect outdoor air
cooling is zero, the total power consumption increases rapidly with
the increase in temperature, as shown in the figure. In such a
high-temperature range, in the conventional air conditioning
system, the condition of "total power consumption (hollow circles
.smallcircle.)=power consumption of refrigeration cycle (hollow
rhombs .diamond.)" is valid. In other words, in the
high-temperature range, since the power consumption of the
refrigeration cycle (hollow rhombs .diamond.) increases rapidly,
the total power consumption also increases rapidly.
[0245] Meanwhile, in the present air conditioning system, even in
the high-temperature range, the power consumption of the
refrigeration cycle (full rhombs .diamond-solid.) increases
gradually with the increase in outdoor air temperature, in a
substantially the same manner as at a lower temperature and does
not increase rapidly. For this reason, in the high-temperature
range, as shown in the figure, the difference in total power
consumption between the conventional air conditioning system and
the present air conditioning system increases as the outdoor air
temperature rises.
[0246] Thus, under the environment in which the outdoor air
temperature is higher than a certain level, the power consumption
of the air conditioning system of the third embodiment is lower
than that of the conventional air conditioning system, and the
energy saving effect increases with the increase in outdoor air
temperature.
[0247] Under the environment with a low outdoor air temperature,
the air conditioning system of the third embodiment can demonstrate
a reverse effect in terms of energy saving. Therefore, the air
conditioning system (variation 1) of the third embodiment shown in
FIG. 4 essentially can be switched at any time to the conventional
air conditioning system by using the configuration shown in FIG.
5A. This, however, depends on the installation environment, and,
for example, where the installation location is in a hot climate
zone, even the configuration shown in FIG. 4 can be used without
any problem.
[0248] Where the degree of cooling of the first refrigerant is high
(the refrigerant temperature is low; the degree of overcooling is
high), the refrigeration effect and refrigeration capacity
increase. This is a well-known matter, as described, for example,
in the reference document (Japanese Patent Application Publication
No. 2010-7975, in particular, paragraphs [0009] and [0038]
thereof). In the above-mentioned reference document, it is
indicated that, for example, where the overcooling degree of the
first refrigerant decreases, the refrigeration effect (the relative
variation amount of enthalpy of the refrigerant in the evaporator)
decreases and, therefore, the refrigeration capacity decreases even
if the refrigerant circulation amount is the same.
[0249] Meanwhile the temperature of the server room, which is the
cooling object space, should be maintained substantially at a set
temperature, and in the example shown in FIG. 6A, the evaporator
should continuously generate cold air with a temperature of about
18.degree. C. Even when the overcooling degree of the refrigerant
decreases, it is necessary, for example, to increase the
refrigerant circulation amount in order to generate cold air with a
temperature of about 18.degree. C., and power consumption,
therefore, increases. In the present air conditioning system, under
the environment with a high outdoor air temperature, the
overcooling degree of the first refrigerant does not become lower
than that of the conventional air conditioning system (refrigerant
cooling by using the outdoor air). Therefore, the increase in power
consumption over that in the conventional air conditioning system
is suppressed. Thus, under the environment with a high outdoor air
temperature, the present air conditioning system demonstrates an
energy saving effect higher than that in the conventional air
conditioning system.
[0250] Further, in the third embodiment, when the unit
configuration, manufacture, and installation are such as explained
with reference to FIGS. 4 and 5A, it is possible to obtain the
effect substantially identical to that of the second embodiment.
Thus, the effects explained in relation to the second embodiment,
namely, (a) compact configuration, (b) reduction of construction
cost due to ductless configuration and wall mounting, (c) size
reduction and improvement of manufacturability by stacked
configuration, and (d) reduction in blow energy (blow power) and
cost reduction by using shared fans, can be also obtained in the
third embodiment.
[0251] The configuration of the third embodiment will be compared
hereinbelow with the conventional configuration with reference to
FIG. 7.
[0252] FIG. 7A shows the operation model of the air conditioning
system of the third embodiment. This figure is substantially the
same as FIG. 6A, and some components therein are omitted. The
components identical to those in FIG. 6A are assigned with the same
reference numerals and detailed explanation thereof is herein
omitted.
[0253] In brief, a refrigeration cycle such as a vapor compression
refrigeration cycle is realized by the condenser 141, evaporator
143, compressor 144, and expansion valve 145 shown in the figure.
The indirect outdoor air cooling function is realized by the pump
146, liquid-gas heat exchanger 147, and liquid-gas heat exchanger
142 shown in the figure.
[0254] The liquid-gas heat exchanger 147, which is the component
through which the outdoor air passes, is installed on the exterior
side (outside the building), and the condenser 141, liquid-gas heat
exchanger 142, and evaporator 143, which are the components through
which the indoor air passes, are installed on the interior side
(inside the building). The installation locations of other
components are not particularly limited.
[0255] FIG. 7C shows the operation model of the conventional air
conditioning system for comparison with the system shown in FIG.
7A.
[0256] As shown in the figures, at least with respect to the model
examples shown in FIGS. 7A and 7C, the configuration of and the
conventional configuration are practically identical, and only the
installation positions of the condenser are different. Because of
such a difference in the installation positions, the condenser in
FIG. 7A is denoted by the reference numeral 141, whereas the
condenser shown in FIG. 7C is denoted by the reference symbol
141'.
[0257] As shown in FIG. 7A, in the air conditioning system of the
third embodiment, the condenser 141 is installed at a position
through which the indoor air passes after passing through the
heating element 140 (server or the like). Meanwhile, as shown in
FIG. 7C, the condenser 141' in the conventional air conditioning
system is installed at a position through which the outdoor air
passes. It is desirable that the outdoor air pass through the
condenser 141' after passing through the liquid-gas heat exchanger
147 (such configuration is not shown in the figure). In the example
shown in the figure the indirect outdoor air cooling function is
stopped (for example, the pump 146 is stopped), for example,
because the outdoor air temperature is very high.
[0258] FIG. 7B is a temperature pattern diagram corresponding to
the air conditioning system of the third embodiment shown in FIG.
7A.
[0259] FIG. 7D is a temperature pattern diagram corresponding to
the conventional air conditioning system shown in FIG. 7C.
[0260] In FIGS. 7B and 7D, the encircling arrows connected to the
heating element 140 (server or the like) indicate temperature
variations relating to the indoor air. The arrows connected to the
compressor 144 and the expansion valve 145 indicate temperature
variations relating to the first refrigerant. Further, Q (Q1a etc.)
means the amount of heat, and L (Lpa etc.) means the power (amount
of consumed power).
[0261] The portion surrounded by a dot line and assigned with the
reference numeral 141a in FIG. 7B represents temperature variations
of the indoor air and refrigerant inside the condenser 141.
Likewise, the portion surrounded by a dot line and assigned with
the reference numeral 141b in FIG. 7D represents temperature
variations of the refrigerant inside the condenser 141'.
[0262] Further, the portion surrounded by a dot line and assigned
with the reference numeral 142a in FIG. 7B represents temperature
variations of the indoor air inside the liquid-gas heat exchanger
142. Likewise, the portion surrounded by a dot line and assigned
with the reference numeral 142b in FIG. 7D represents temperature
variations of the indoor air inside the liquid-gas heat exchanger
142 (however, as shown in the figure, the temperature of the indoor
air does not change).
[0263] Further, the portion surrounded by a dot line and assigned
with the reference numeral 143a in FIG. 7B represents temperature
variations of the indoor air and refrigerant inside the evaporator
143. Likewise, the portion surrounded by a dot line and assigned
with the reference numeral 143b in FIG. 7D represents temperature
variations of the indoor air and refrigerant inside the evaporator
143.
[0264] In the configuration shown in FIG. 7B, the exchange of the
amount of heat Q1a is performed between the indoor air and the
first refrigerant in the condenser 141. As a result, as shown by
the reference numeral 141a in the figure, the temperature of the
indoor air rises and the temperature of the first refrigerant
decreases to the temperature level of the return air (RA) shown in
the figure. The return air (RA) is the indoor air serving as the
return air from the heating element 140 (server or the like). As
also explained with reference to FIG. 6A, this is the ideal
temperature pattern diagram for simulation, and actually such a
diagram is not obtained. For example, although the temperature of
the first refrigerant greatly decreases, it does not decrease to
the temperature level of the return air (RA) as shown in the figure
and is somewhat higher than that.
[0265] When the indoor air then passes through the liquid-gas heat
exchanger 142, the quantity of heat Q2a is drawn by the indirect
outdoor air cooling function (indirectly exchanges heat with the
outdoor air, the heat is radiated to the exterior side (outside of
the building)). As a result, the temperature of the indoor air
drops to the temperature level of the outdoor air (OA), for
example, as shown by the reference numeral 142a in the figure.
[0266] Then, as shown by the reference numeral 143a in the figure,
the heat in an amount of Q3a is drawn from the indoor air in the
evaporator 143, and the temperature of the indoor air decreases to
the temperature level of the supplied air (SA) shown in the figure.
The supplied air (SA), as referred herein, is the indoor air (cold
air) supplied to the heating element 140 (server or the like). The
temperature of the refrigerant in the evaporator 143 decreases to
the "J" level shown in the figure.
[0267] Meanwhile, as shown in FIG. 7D, in the conventional
configuration, the indoor air heated by the amount of heat QH in
the heating element 140 (server or the like) does not pass through
the condenser 141', and therefore the temperature thereof does not
change (see the reference numeral 141b). Further, in the example
shown in FIG. 7C, since the indirect outdoor air cooling function
is stopped, even through the air passes through the liquid-gas heat
exchanger 142, the temperature thereof does not change (see the
reference numeral 142b) and remains at the temperature level of the
return air (RA) shown in the figure. Then, as shown by the
reference numeral 143b in the figure, the heat in an amount of Q3b
is drawn from the indoor air in the evaporator 143, and the
temperature of the indoor air decreases to the temperature level of
the supplied air (SA) shown in the figure.
[0268] Meanwhile, the first refrigerant exchanges heat in an amount
of Q1b with the outdoor air in the condenser 141' installed on the
exterior side (outside the building), and the temperature of the
first refrigerant decreases to the temperature level of the outdoor
air (OA) shown in the figure. The temperature of the first
refrigerant is then decreased by the expansion valve 145 to the "J"
temperature level shown in the figure, and the first refrigerant is
thereafter supplied to the evaporator 143.
[0269] In this case, as shown in FIGS. 7B and 7D, the temperature
of the first refrigerant before it enters the expansion valve 145
is RA in FIG. 7B and OA in FIG. 7D, and RA<OA. In other words,
in the third embodiment, the temperature of the first refrigerant
before the expansion valve 145 is lower than that in the
conventional configuration. As a result, as has already been
mentioned hereinabove, power consumption of the refrigeration cycle
in the third embodiment can be small. In other words, where the
power (power consumption) (mainly, the power (power consumption) of
the compressor 144) of the refrigeration cycle in the third
embodiment is denoted by Lca and the power (power consumption)
(mainly, the power (power consumption) of the compressor 144) of
the refrigeration cycle in the conventional configuration is
denoted by Lcb, as shown in the figure, the condition of Lcb>Lca
is fulfilled. In other words, the temperature of the return air
(RA) is lower than the temperature of the outdoor air (OA) as in
the example shown in the figure.
[0270] However, in the example shown in FIG. 7, in the conventional
configuration, the power of the indirect outdoor air cooling
function is stopped and, therefore, the power consumption is "0",
whereas in the configuration of the third embodiment, the power
(power consumption) Lpa of the indirect outdoor air cooling
function is added. Therefore, in this example, when the condition
of "Lcb>Lca+Lpa" is fulfilled, the air conditioning system of
the third embodiment consumes less power than the conventional air
conditioning system.
[0271] FIG. 10 is a simplified configuration diagram of the entire
system including the air conditioning system of the third
embodiment.
[0272] The air conditioning system of the third embodiment is not
limited to the above-described example, and can be configured, for
example, as shown in FIG. 10. The configuration shown in FIG. 10
uses the structural components of the example shown in FIG. 4 and
those components are assigned with same reference numerals as shown
in FIG. 4. As mentioned hereinabove, an example in which the
components are stacked and integrated is not limiting. Therefore,
for example, the configuration such as shown in FIG. 10 may be
used.
[0273] In the example shown in FIG. 10, the air conditioning system
of the third embodiment is assumed to be constituted by a heat pump
151 and a heat exchanger 152 shown in the figure. The heat pump 151
is constituted by the evaporator 91d, compressor 92, condenser 91b,
and expansion valve 93, and the refrigerant circulates in the order
of "evaporator 91d.fwdarw.compressor 92.fwdarw.condenser
91b.fwdarw.expansion valve 93.fwdarw.evaporator 91d" through the
refrigerant piping 95 connected to the aforementioned
components.
[0274] The heat exchanger 152 is constituted by the liquid-gas heat
exchangers 91c and 81b and the piping 96 connecting the heat
exchangers (this configuration is not shown in the figure).
[0275] The cold air (indoor air) delivered from the heat pump 151
enters the server room through the under-floor space, cools the
server device, and becomes the warm air. The warm air (indoor air)
flows into the heat pump 151 through the attic space, passes
through the condenser 91b, whereby the temperature thereof is
raised, and then flows into the heat exchanger 152. Indirect heat
exchange is performed between the indoor air and outdoor air inside
the heat exchanger 152, and the temperature of the indoor air
decreases. The indoor air with the decreased temperature flows into
the heat pump 151 and is cooled when passing through the evaporator
91d. The resultant cold air is delivered into the under-floor
space, as described hereinabove.
[0276] The fourth embodiment will be explained below.
[0277] FIG. 11 shows the configuration of the air conditioning
system (variation 1) of the fourth embodiment.
[0278] FIG. 12 shows the configuration of the air conditioning
system (variation 2) of the fourth embodiment.
[0279] FIG. 13 shows the operation model of the air conditioning
system of the fourth embodiment.
[0280] First, the air conditioning system (variation 1) of the
fourth embodiment will be explained with reference to FIG. 11. In
FIG. 11, the components substantially same as those shown in FIG.
5B are assigned with the reference symbols same as those in FIG. 5B
and the explanation thereof is herein omitted or simplified.
[0281] The air conditioning system (variation 1) of fourth
embodiment that is shown in FIG. 11 is constituted by an outdoor
air unit 160 and an indoor air unit 170. Those outdoor air unit 160
and the indoor air unit 170 are provided on the exterior side
(outside the building) and interior side (inside the building),
with the wall 1 being interposed therebetween, in a substantially
the same manner as the outdoor air unit 110 and the indoor air unit
120 shown in FIG. 5B.
[0282] The manufacturing and installation methods of those outdoor
air unit 160 and the indoor air unit 170 may be substantially
identical to the manufacturing and installation methods of those
outdoor air unit 110 and the indoor air unit 120 shown in FIGS. 5A
and 5B. The same is true for the configuration shown in FIG. 12.
Further, the air conditioning system of the fourth embodiment
demonstrates the effect substantially identical to that of the air
conditioning system of the third embodiment. In addition the
specific effect of the fourth embodiment which is described
hereinbelow is also obtained.
[0283] The outdoor air unit 160 has a stack 111. The stack 111 has
a fan 111a, a liquid-gas heat exchanger 111b, and a condenser 111c
and is configured by stacking and integrating those components as
shown in the figure. Those components are assigned with the
reference symbols of the components of the stack 111 shown in FIG.
5B and the explanation thereof is herein omitted or simplified. The
same is true for the configuration relating to the below-described
three-way valve 112'.
[0284] An expansion valve 123 and a compressor 113 are each
provided in either of the outdoor air unit 160 and the indoor air
unit 170. In the example shown in the figure, the expansion valve
123 is provided in the indoor air unit 170, and the compressor 113
is provided in the outdoor air unit 160, but the embodiment is not
limited to this example.
[0285] Further, in the same manner as shown in FIG. 5B, the
expansion valve 123, compressor 113, condenser 111c, and condenser
171b are provided on the refrigerant piping 125 where the first
refrigerant circulates. In the configuration shown in FIG. 11, the
evaporator 172 is also provided on the refrigerant piping 125. The
evaporator 172 will be described hereinbelow in greater detail.
[0286] In the configuration shown in FIG. 11, similarly to the
configuration shown in FIG. 5B, a three-way valve 112', which is an
example of a switching device, is provided in the refrigerant
piping 125 along the way thereof. The refrigerant piping 125 is
branched from the three-way valve 112' into a refrigerant piping
125a and a refrigerant piping 125b, which are shown in the figure.
The three-way valve 112' is provided at the rear stage (downstream
side) of the condenser 111c. The refrigerant piping (branch piping)
125a is connected to the condenser 171b in the indoor air unit 170
and merges with the refrigerant piping (branch piping) 125b on the
downstream side of the condenser 171b (merges in the merging point
R shown in the figure and then again becomes the single refrigerant
piping 125). The refrigerant piping 125 after merging in the
merging point R is connected to the expansion valve 123. Check
valves 122a and 122b are provided, close to and before the merging
point R in the refrigerant piping 125a and the refrigerant piping
125b, respectively. As a result, the counterflow of the first
refrigerant is prevented.
[0287] In the configuration shown in FIG. 11, the components
substantially the same as those shown in FIG. 5B are explained in a
simple manner (obviously, with the exception of those components
that are assigned with the reference numerals other than those in
FIG. 5B, such as the evaporator 172).
[0288] In the configuration shown in FIG. 11, the stack 171 shown
in the figure is provided on the indoor air unit 170 side. The
stack 171 is constituted by a fan 171a, a condenser 171b, and a
liquid-gas heat exchanger 171c. The difference between the stack
171 and the stack 121 is that the stack 171 does not include the
evaporator 121d. Therefore, the fan 171a, condenser 171b, and
liquid-gas heat exchanger 171c shown in the figure are by
themselves substantially the same as the fan 121a, condenser 121b,
and liquid-gas heat exchanger 121c in the stack 121.
[0289] The indoor air passes through in the order of condenser
171b.fwdarw.liquid-gas heat exchanger 171c because of the indoor
air flow (shown by a one-dot-dash arrow in the figure) formed by
the fan 121a.
[0290] The configuration shown in the figure is an example, and the
embodiment is not limited to this example. Basically, the stack 171
is provided inside the indoor air unit 170, and the stack 111 is
provided in the outdoor air unit 160, but other components may be
provided in either of the indoor air unit 170 and the outdoor air
unit 160. Therefore, for example, the evaporator 172 may be
provided on the outdoor air unit 160 side.
[0291] In the present configuration example, the evaporator 172 is
provided, as shown in the figure, instead of using the
configuration without the evaporator 121d, as described
hereinabove. In other words, in FIG. 5B, the evaporator 121d is
provided between the expansion valve 123 and the compressor 113 (it
goes without saying, that the evaporator is provided on the
refrigerant piping 125). By contrast, in the present configuration,
the evaporator 172 is provided between the expansion valve 123 and
the compressor 113 (on the refrigerant piping 125).
[0292] The evaporator 121d and the evaporator 172 have different
configurations. The evaporator 121d can be considered as a
liquid-gas heat exchanger and performs heat exchange between any
refrigerant and air (indoor air) in the form of refrigerant
evaporation. In other words, it is a typical evaporator suitable
for a typical air conditioner (air conditioning device or the
like).
[0293] By contrast, the evaporator 172 can be considered as a
liquid-liquid heat exchanger, rather than the liquid-gas heat
exchanger, of a well-known configuration. Therefore, the evaporator
172 does not perform heat exchange with the air (indoor air), which
is gas. The evaporator 172 basically does not constitute part of
the stack 171 through which the indoor air passes. The installation
position of the evaporator 172 is not particularly specified, and
it is basically assumed to be provided in the indoor air unit 170
or the outdoor air unit 160.
[0294] As mentioned hereinabove, the evaporator 172 is provided on
the refrigerant piping 125. Therefore, the first refrigerant passes
inside thereof (this is not shown in the figure). Furthermore, as
shown in the figure, the evaporator 172 is connected not only to
the refrigerant piping 125, but also to the piping 162. Similarly
to the piping 126 shown in FIG. 5B, the piping 162 is by itself
configured to circulate the second refrigerant (for example, water)
in the liquid-gas heat exchanger 111b of the outdoor air unit 160
and the liquid-gas heat exchanger 171c of the indoor air unit 170.
Similarly to the configuration shown in FIG. 5B, a pump 124 for
circulating the second refrigerant is provided at a random location
on the piping 162.
[0295] As mentioned hereinabove, the evaporator 172 is also
connected to the piping 162. Not only the first refrigerant, but
also the second refrigerant passes through in the evaporator 172.
Basically, as shown in the figure, the configuration is used in
which the evaporator 172 is provided before (on the upstream side)
of the liquid-gas heat exchanger 171c. As a result, as will be
described hereinbelow, the second refrigerant cooled by the first
refrigerant in the evaporator 172 flows into the liquid-gas heat
exchanger 171c located on the downstream side.
[0296] The difference between the example shown in the figure and
the configuration in FIG. 5B is that the former is also
additionally provided with a three-way valve 161, but the three-way
valve 161 is not a mandatory component. The three-way valve 161
will be explained below.
[0297] As mentioned hereinabove, the first refrigerant and the
second refrigerant pass through inside the evaporator 172 (the
internal configuration thereof is not shown in the figure).
Similarly to the case of the evaporator 121d, the first refrigerant
evaporates inside the evaporator 172, and in this case the heat is
drawn from the surroundings (the surroundings are cooled). In the
case of the evaporator 121d, the air (indoor air) passes inside
thereof and, therefore, the air (indoor air) is cooled. By
contrast, in the case of the evaporator 172, the second refrigerant
passes inside thereof, as mentioned hereinabove, and therefore the
second refrigerant is cooled by the first refrigerant.
[0298] In the case of the configuration shown in FIG. 5B, the
second refrigerant is basically cooled by heat exchange with the
outdoor air in the liquid-gas heat exchanger 111b of the outdoor
air unit 110, and the second refrigerant cooled by the outdoor air
is supplied into the liquid-gas heat exchanger 121c of the indoor
air unit 120. As a result, heat exchange between the second
refrigerant and the indoor air is performed inside the liquid-gas
heat exchanger 121c, and the indoor air is cooled by the second
refrigerant. Meanwhile, in the case of the configuration shown in
FIG. 11, the second refrigerant is further cooled inside the
evaporator 172, as mentioned hereinabove, before being supplied to
the liquid-gas heat exchanger 171c.
[0299] It can be also assumed that in the configuration shown in
FIG. 5B, the air (indoor air) is directly cooled by the first
refrigerant, whereas in the configuration shown in FIG. 11, air
(indoor air) is indirectly cooled via the second refrigerant.
[0300] In the configuration shown in FIG. 11, the indoor air
(return air; warm air) flowing into the indoor air unit 170 from
the attic space, for example, shown in FIG. 1 via the indoor air
inlet 128 is initially heated while passing through the condenser
171b and thereafter cooled while passing through the liquid-gas
heat exchanger 171c. The cooled indoor air (cold air) is discharged
from the indoor air outlet 127 and delivered into the under-floor
space, for example, shown in FIG. 1. The cold air is thus supplied
into the cooling object space (the space of server setting).
[0301] Further, the controller 130 controls the compressor 113 or
the circulating pump 124 to control the flow rate of the first
refrigerant or the second refrigerant, for example, so that the
temperature of the cold air discharged from the indoor air outlet
127 becomes substantially equal to a predetermined set temperature
(for example, 18.degree. C.). The controller 130 controls, for
example, the compressor 113 or the circulating pump 124, for
example, via the a signal line 131 shown in the below-described
FIG. 13.
[0302] The evaporator 172 is a "liquid-liquid heat exchanger"
performing heat exchange between liquid with a relatively low
temperature (first refrigerant) and liquid with a relatively high
temperature (second refrigerant), more specifically, for example,
the so-called "liquid-liquid plate-type heat exchanger".
[0303] The configuration relating to the three-way valve 161 will
be explained below.
[0304] The configuration shown in FIG. 5B requires that the second
refrigerant exchange heat with the outdoor air by flowing into the
liquid-gas heat exchanger 111b. By contrast, the configuration
shown in FIG. 11 uses the three-way valve 161 which makes it
possible for the second refrigerant not to flow into the liquid-gas
heat exchanger 111b (to bypass the heat exchanger). In the case of
the present configuration, the second refrigerant is cooled by the
first refrigerant in the evaporator 172 even when no heat exchange
with the outdoor air is performed.
[0305] The three-way valve 161 is a valve for dividing the flow
path of the piping into two flow paths. This valve has three piping
connection ports, one of which is for inflow (called "inlet") and
the other two are for outflow (called "outlets"). The three-way
valve 161 is connected to the piping 162 and causes the second
refrigerant circulated inside the piping 162 by the circulating
pump 124 to flow in from the inlet and flow out from one of the two
outlets. The piping 162 can be also assumed to be branched into two
by the three-way valve 161, and branching into a branch piping 162a
and a branch piping 162b can be considered.
[0306] One of the two outlets of the three-way valve 161 is
connected to the branch piping 162a and the other is connected to
the branch piping 162b. The branch piping 162a passes through the
liquid-gas heat exchanger 111b and then merges with the branch
piping 162b in the merging point Q shown in the figure and again
becomes a single piping 162, and this piping 162 is connected to
the evaporator 172 of the last stage. Meanwhile, the branch piping
162b is connected to and merges with the branch piping 162a in the
merging point Q.
[0307] Where the second refrigerant flows out from the three-way
valve 161 on the branch piping 162a, the second refrigerant passes
through the liquid-gas heat exchanger 111b and then flows into the
evaporator 172. Meanwhile, where the second refrigerant flows out
from the three-way valve 161 on the branch piping 162b, the second
refrigerant flows directly into the evaporator 172, without passing
through the liquid-gas heat exchanger 111b.
[0308] Basically, in a state in which the second refrigerant can be
cooled by the outdoor air in the liquid-gas heat exchanger 111b,
the second refrigerant passes through the liquid-gas heat exchanger
111b. In other words, for example, in a state in which "outdoor air
temperature>temperature of the second refrigerant flowing into
the liquid-gas heat exchanger 111b", the second refrigerant flows
out of the three-way valve 161 into the branch piping 162b
(bypasses the liquid-gas heat exchanger 111b). As a result, it is
possible to avoid the situation in which the temperature of the
second refrigerant is raised in the liquid-gas heat exchanger
111b.
[0309] However, not being limited to such an example, a
configuration which is not provided with the three-way valve 161
(that is, the piping 162 is not branched into two pieces of piping)
may be also used. In other words, the configuration same as that
shown in FIG. 5B may be used with respect to the second refrigerant
so that the second refrigerant necessarily flows into the
liquid-gas heat exchanger 111b.
[0310] A check valve may be also provided in the branch piping 162a
before the merging point Q with the branch piping 162b (such
configuration is not shown in the figure). As a result, when the
second refrigerant flows out from the three-way valve 161 into the
branch piping 162b, the second refrigerant can be prevented from
flowing into the liquid-gas heat exchanger 111b.
[0311] The air conditioning system (variation 2) of the fourth
embodiment shown FIG. 12 will be explained below.
[0312] The configuration shown in FIG. 12 can be considered as a
modification of the configuration shown in FIG. 11 and is
substantially the same as the configuration shown in FIG. 11, while
being only partially different therefrom. Therefore, the
explanation of the components in FIG. 12 that are substantially the
same as those shown in FIG. 11 is omitted or simplified. The
relationship (difference) between the configurations in FIG. 11 and
FIG. 12 may be considered to be the same as that between the
configurations shown in FIGS. 5A and 5B.
[0313] Thus, the configuration shown in FIG. 12 differs from that
shown in FIG. 11 in that a three-way valve is installed on the
refrigerant piping 125. The configuration shown in FIG. 12 is
constituted by an outdoor air unit 160' and an indoor air unit 170.
The indoor air unit may be the same as the indoor air unit 170
shown in FIG. 11 and is, therefore, assigned with the same
reference numeral "170". Meanwhile, the outdoor air unit is
somewhat different from the outdoor air unit 160 shown in FIG. 11
and is, therefore, assigned with the reference numeral "160'".
[0314] Similarly to the configuration shown in FIG. 5B, in the
outdoor air unit 160 shown in FIG. 11, a three-way valve 112' is
provided on the outflow side (downstream side) of the condenser
111c, and the first refrigerant is necessarily caused to flow
through the condenser 111c. The three-way valve 112' controls
whether or not to cause also the first refrigerant to flow through
the condenser 171b.
[0315] Meanwhile, similarly to the configuration shown in FIG. 5A,
in outdoor air unit 160' shown in FIG. 12, a three-way valve 112 is
provided on the inflow side (upstream side) of the condenser 111c.
The first refrigerant is switched by the three-way valve 112 in
either of the "state in which the first refrigerant passes through
the condenser 111c, but does not pass through the condenser 121b"
and the "state in which the first refrigerant does not pass through
the condenser 111c, but passes through the condenser 121b".
[0316] The configuration shown in FIG. 12 is explained hereinabove
in a simple manner only with respect to the differences between
this configuration and that shown in FIG. 11. The functions and
effects of the configuration shown in FIG. 12 are substantially the
same as those of the configuration shown in FIG. 11.
[0317] FIG. 13 is explained hereinbelow.
[0318] FIG. 13A shows the operation model of the above-described
air conditioning system of the fourth embodiment. Further, FIG. 13B
shows the simulation results relating to the reduction in power
consumption in the fourth embodiment.
[0319] First, FIG. 13A will be explained. Similarly to FIG. 6A,
each temperature shown in FIG. 13A indicates an example based on
the simulation result and is not limited to this example.
[0320] FIG. 13A corresponds to the configuration example shown in
FIG. 12 and includes reference numerals of the components shown in
FIG. 12. However, the heating element 140 shown in the figure is
the heating element 140 shown in FIG. 6A and corresponds, for
example, to the heating element 101 (server device or the like)
shown in FIG. 1. FIG. 13A is assumed to correspond to the case in
which in the configuration shown in FIG. 12, a state is assumed
such that the three-way valve 112 does not allow the first
refrigerant to pass through the condenser 111c side. Therefore, the
condenser 111c is not shown in FIG. 13A, and the condenser 171b is
shown on the downstream side of the compressor 113.
[0321] As shown by a thick-line arrow in FIG. 13A, the interior air
(indoor air) circulates through the heating element 140, condenser
171b, and liquid-gas heat exchanger 171c.
[0322] Further, the first refrigerant circulates in the
configuration provided on the refrigerant piping 125 shown in the
figure. Thus, as shown by a thin-line arrow in the figure, the
first refrigerant circulates in the compressor 113, condenser 171b,
expansion valve 123, and evaporator (liquid-liquid heat exchanger)
172.
[0323] The second refrigerant circulates in the components on the
piping 162 shown in the figure. Thus, as shown by a thin
dash-dot-dash arrow in the figure, the second refrigerant
circulates in the circulating pump 124, liquid-gas heat exchanger
171c, liquid-gas heat exchanger 111b, and evaporator (liquid-liquid
heat exchanger) 172.
[0324] The indoor air that has been cooled to 32.degree. C. by
cooling the heating element 140 in a substantially the same manner
as shown in FIG. 6A passes through the condenser 171b, whereby the
temperature of the indoor air rises to 55.degree. C. The indoor air
with a temperature of 55.degree. C. is cooled by heat exchange with
the second refrigerant and the temperature of the indoor air drops
(to 18.degree. C. in the example shown in the figure) when the
indoor air passes through the liquid-gas heat exchanger 171c. This
indoor air with a temperature of 18.degree. C. is delivered, for
example, to the under-floor space shown in FIG. 1, whereby the
heating element 140 is cooled.
[0325] In the case shown in FIG. 6A, the indoor air with a
temperature of 55.degree. C. is cooled by heat exchange with the
second refrigerant and the temperature of the indoor air drops when
the indoor air passes through the liquid-gas heat exchanger 142,
but since the temperature of the second refrigerant is affected by
the outdoor air temperature (for example, 36.degree. C.), the
temperature of the indoor air cannot be reduced to a set
temperature (18.degree. C. or the like). The temperature of the
indoor air is reduced to the set temperature (18.degree. C. or the
like) by the last-stage evaporator 143.
[0326] By contrast, in the example shown in FIG. 13A, the
temperature of the second refrigerant can be made lower than the
outdoor air temperature (equal to or less than the set temperature;
18.degree. C. in the present example) by the evaporator
(liquid-liquid heat exchanger) 172, and the temperature of the
indoor air can be reduced to the set temperature (18.degree. C. or
the like) in the liquid-gas heat exchanger 171c.
[0327] In this case, as mentioned hereinabove (and as shown in FIG.
13A), both the first refrigerant and the second refrigerant pass
through the evaporator (liquid-liquid heat exchanger) 172, and the
first refrigerant and the second refrigerant exchange heat inside
the evaporator 172. In the example shown in the figure, the
temperature of the first refrigerant flowing into the evaporator
172 is 10.degree. C. Meanwhile, the temperature of the second
refrigerant flowing out of the evaporator 172 (in other words, the
temperature of the second refrigerant after heat exchange with the
first refrigerant) is 18.degree. C.
[0328] Here, the temperature of the second refrigerant flowing into
the evaporator 172 is not shown in the figure, but because the
second refrigerant flows into the evaporator 172 after undergoing
heat exchange with the outdoor air (36.degree. C.) in the
liquid-gas heat exchanger 111b, the temperature of the second
refrigerant flowing into the evaporator 172 is basically not less
than the outdoor air temperature (36.degree. C.). In other words,
in the example shown in the figure, heat exchange between the first
refrigerant at a temperature of 10.degree. C. and the second
refrigerant with a temperature equal to or higher than 36.degree.
C. is performed in the evaporator 172. Therefore, the second
refrigerant is obviously cooled by the first refrigerant, and in
the example shown in the figure, the second refrigerant is cooled
to 18.degree. C. as described hereinabove.
[0329] The temperature of the second refrigerant (denoted by
temperature Ta) flowing from the liquid-gas heat exchanger 171c
also differs depending on the flow rate of the second refrigerant
(this relationship is not shown in the figure). In other words,
when the flow rate of the second refrigerant is small, the
temperature Ta can become, for example, a temperature (e.g., equal
to or higher than 50.degree. C.) close to the indoor air
temperature (55.degree. C.). Meanwhile, when the flow rate of the
second refrigerant is high, the temperature Ta can become lower
than the outdoor air temperature (36.degree. C.)
[0330] With consideration for such a case, the configuration
provided with the three-way valve 161 can be also suggested. Thus,
for example, when "Ta<outdoor air temperature", the controller
130 may control the three-way valve 161 to obtain a state in which
the second refrigerant bypasses (does not pass through) the
liquid-gas heat exchanger 111b.
[0331] In such a case, a "mixing/stirring unit" (not shown in the
figure) may be provided at the last stage (downstream side with
respect to the indoor air) of the liquid-gas heat exchanger 171c.
The "mixing/stirring unit" has a well-known configuration and is,
therefore, neither explained nor shown in the figure herein. This
unit is configured to obtain a substantially uniform temperature
distribution of gas such as air therein by mixing/stirring inside
the unit. In other words, the temperature of the indoor air (cold
air) flowing from the liquid-gas heat exchanger 171c is taken as
18.degree. C., as described hereinabove, and it means the
temperature in the case in which the temperature distribution is
substantially uniform. However, the temperature distribution is
actually not substantially uniform, and it can be assumed that
there are portions with a low temperature and portions with a high
temperature (relative to 18.degree. C.). Therefore, the
configuration in which the "mixing/stirring unit" (not shown in the
figure) is provided to obtain a substantially uniform temperature
distribution may be also used.
[0332] It is also possible that when the cold air reaches the
heating element 140, the temperature distribution of the cold air
is substantially uniform due to natural mixing taking place as the
cold air flows in the under-floor space. Therefore, in some cases,
it is not necessary to provide the "mixing/stirring unit" (not
shown in the figure).
[0333] The configuration relating to the refrigeration cycle in
which the first refrigerant circulates (the refrigerant piping 125
and various components provided on the refrigerant piping 125) can
be considered to be substantially the same as the configuration
shown in FIG. 6A, except that the evaporator (liquid-gas heat
exchanger) 143 is replaced with the evaporator (liquid-liquid heat
exchanger) 172. Accordingly, where such a configuration is
explained in a simple manner, the first refrigerant assumes a
temperature of 25.degree. C. due to heat exchange with the second
refrigerant in the evaporator (liquid-liquid heat exchanger) 172
and is then heated to 66.degree. C. by compression in the
compressor 113. Such first refrigerant with a temperature of
66.degree. C. is reduced in temperature (to 32.degree. C.) by heat
exchange with the indoor air in the condenser 171b and then further
reduced in temperature (to 10.degree. C.) by the expansion valve
123. The first refrigerant with a temperature of 10.degree. C.
exchanges heat with the second refrigerant in the evaporator 172 as
described hereinabove.
[0334] The simulation results shown in FIG. 13B will be explained
below.
[0335] In the graph shown in FIG. 13B, similarly to the graph shown
in FIG. 6B, the outdoor air temperature (.degree. C.) is plotted
against the abscissa, and the consumed power (kW) is plotted
against the ordinate. Hollow circles (.smallcircle.) in the graph
represent data for the conventional system, and full circles ( )
represent data for the air conditioning system of the fourth
embodiment. Those data correspond to "total power consumption" in
FIG. 6B. The conventional air conditioning system is, for example,
the air conditioning system shown in FIG. 14, but the embodiment is
not being limited to this example, and it can be also considered,
for example, as the air conditioning system of the first embodiment
or the second embodiment.
[0336] As shown in the figure, where the outdoor air temperature is
comparatively low, the power consumption of the conventional air
conditioning system is not substantially different from that of the
present air conditioning system (air conditioning system of the
fourth embodiment).
[0337] However, where the outdoor air temperature becomes higher
than a certain level (referred to as a high-temperature range; for
example, a level of above 30.degree. C. can be selected as a
criterion), the total power consumption in the conventional air
conditioning system rises rapidly with the increase in temperature,
as shown in the figure.
[0338] Meanwhile, in the air conditioning system of the fourth
embodiment, even in the high-temperature range, the power
consumption increases gradually with the increase in outdoor air
temperature in a substantially the same manner as at a lower
temperature and does not increase rapidly. For this reason, in the
high-temperature range, as shown in the figure, the difference in
total power consumption between the conventional air conditioning
system and the present air conditioning system increases as the
outdoor air temperature rises.
[0339] Thus, under the environment in which the outdoor air
temperature is higher than a certain level, the power consumption
of the air conditioning system of the fourth embodiment is lower
than that of the conventional air conditioning system, and the
energy saving effect increases with the increase in outdoor air
temperature.
[0340] The example of configuration illustrated by FIGS. 11 and 12
is one example of the present invention and is not being limited to
this. For example, FIG. 9 shows a modification of the configuration
shown in FIG. 5A, and a similar modification may be also considered
with respect to the configuration shown in FIGS. 11 and 12. This
modification is not shown in the figure, but can be clearly
understood from the relationship between FIG. 5A and FIG. 9.
[0341] With the above-described air conditioning system (variation
1) and (variation 2) of the fourth embodiment, the following
effects can be obtained in addition to the effects that are
substantially the same as those obtained in the above-described air
conditioning system of the third embodiment. [0342] The evaporator
(evaporator 121d etc.) of the other examples is a liquid-gas heat
exchanger that performs heat exchange between the air (indoor air)
and liquid (first refrigerant), whereas the evaporator 172 is, as
mentioned hereinabove, a liquid-liquid heat exchanger. The heat
exchange efficiency in the liquid-liquid heat exchanger is
typically higher than that in a liquid-gas heat exchanger.
Therefore, where the heat exchange capacity is assumed to be the
same, the liquid-liquid heat exchanger can be made smaller than the
liquid-gas heat exchanger (for example, the volume of the
evaporator 172 can be about 5% to 10% that of the evaporator 121d).
[0343] In the third embodiment, two heat exchangers (for example,
in FIGS. 5A sand 5B, the liquid-gas heat exchanger 121c and the
evaporator 121d) are provided on the path where the indoor air
flows. By contrast, in the configuration shown in FIGS. 11 and 12,
the evaporator 121d is removed and the evaporator 172 is not
provided on the path where the indoor air flows. Since the
evaporator 121d is thus removed, the flow pressure loss of the
indoor air is reduced whereby the flow efficiency is increased.
This results, for example, in reduced power consumption in the fan
171a and the like.
[0344] The evaporator 121d and the evaporator 172 both perform
cooling with the first refrigerant, but the evaporator 121d cools
the air, whereas the evaporator 172 cools the liquid (second
refrigerant). Since the cooling medium is liquid which has thermal
capacity higher than the air, temperature variations become smooth
and temperature control is stabilized.
[0345] For example, let us assume a case in which the temperature
of the first refrigerant temporarily changes significantly for some
reason. In such a case, in the conventional system, the temperature
of the air (indoor air) that is directly cooled by the first
refrigerant also changes significantly. By contrast, in the present
system, the temperature of the second refrigerant changes, but the
temperature variations become gradual (in comparison with the case
of air) and, therefore, temperature variations of the air (indoor
air) that is cooled by the second refrigerant also become gradual.
As a result, temperature control can be easily performed to
maintain the indoor air temperature close to the set value (for
example, 18.degree. C.)
[0346] When the outdoor air temperature is high (for example, the
case in which the temperature of the second refrigerant flowing
into the liquid-gas heat exchanger 111b is less than the outdoor
air temperature), the second refrigerant is caused by the three-way
valve 161 to circulate so as to bypass the liquid-gas heat
exchanger 111b. As a result, the event in which the second
refrigerant is heated by the outdoor air and raised in temperature
can be avoided.
[0347] With the air conditioning system using outdoor air in
accordance with the present invention, and the indoor air unit and
outdoor air unit thereof, it is possible to provide an air
conditioning system in which the interior air is cooled with low
energy consumption by using outdoor air and the indoor air cooling
using outdoor air can be realized even when the outdoor air
temperature is high, and it is also possible to reduce energy
consumption in an air conditioning system with a compression-type
refrigeration cycle.
* * * * *