U.S. patent application number 14/400458 was filed with the patent office on 2015-05-14 for air-conditioning apparatus.
This patent application is currently assigned to Mitsubishi Electric Corporation. The applicant listed for this patent is Koji Azuma, Takayoshi Honda, Tomokazu Kawagoe, Daisuke Shimamoto. Invention is credited to Koji Azuma, Takayoshi Honda, Tomokazu Kawagoe, Daisuke Shimamoto.
Application Number | 20150128628 14/400458 |
Document ID | / |
Family ID | 49996704 |
Filed Date | 2015-05-14 |
United States Patent
Application |
20150128628 |
Kind Code |
A1 |
Kawagoe; Tomokazu ; et
al. |
May 14, 2015 |
AIR-CONDITIONING APPARATUS
Abstract
An air-conditioning apparatus includes a heat source-side unit
including a compressor that compresses a refrigerant and a heat
source-side heat exchanger, a plurality of use-side units each
including a use-side heat exchanger, and a plurality of
intermediate heat exchangers connected to the heat source-side unit
and to the use-side units. A target determination device detects
condensation status of each of the use-side units and determines
whether to perform condensation suppression control. The use-side
unit determined by the target determination means to be subjected
to the condensation suppression control is connected to an
intermediate heat exchanger for adjustment. A refrigerant circuit
control device controls a temperature of the refrigerant flowing
into the intermediate heat exchanger for adjustment so that the
heat medium temperature T of the heat medium flowing into at least
one use-side unit enters a predetermined target set temperature
range.
Inventors: |
Kawagoe; Tomokazu; (Tokyo,
JP) ; Shimamoto; Daisuke; (Tokyo, JP) ; Azuma;
Koji; (Tokyo, JP) ; Honda; Takayoshi; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kawagoe; Tomokazu
Shimamoto; Daisuke
Azuma; Koji
Honda; Takayoshi |
Tokyo
Tokyo
Tokyo
Tokyo |
|
JP
JP
JP
JP |
|
|
Assignee: |
Mitsubishi Electric
Corporation
Tokyo
JP
|
Family ID: |
49996704 |
Appl. No.: |
14/400458 |
Filed: |
July 24, 2012 |
PCT Filed: |
July 24, 2012 |
PCT NO: |
PCT/JP2012/004708 |
371 Date: |
November 11, 2014 |
Current U.S.
Class: |
62/160 |
Current CPC
Class: |
F24F 11/83 20180101;
F25B 2600/25 20130101; F25B 2313/0231 20130101; F25B 49/02
20130101; F24F 2140/30 20180101; F25B 2313/0233 20130101; F25B
2700/21161 20130101; F25B 2313/0312 20130101; F25B 2313/003
20130101; F25B 2313/02741 20130101; F25B 9/008 20130101; F25B 30/02
20130101; F25B 41/046 20130101; F25B 2313/0314 20130101; F25B
2313/006 20130101; F25B 13/00 20130101 |
Class at
Publication: |
62/160 |
International
Class: |
F25B 49/02 20060101
F25B049/02; F25B 41/04 20060101 F25B041/04; F25B 30/02 20060101
F25B030/02; F25B 13/00 20060101 F25B013/00 |
Claims
1. An air-conditioning apparatus comprising: a heat source-side
unit including a compressor that compresses a refrigerant and a
heat source-side heat exchanger that exchanges heat between air and
the refrigerant; a plurality of use-side units each including a
use-side heat exchanger that exchanges heat between air and a heat
medium; a plurality of intermediate heat exchangers connected to
the heat source-side unit via a refrigerant pipe and connected to
the use-side units via a heat medium pipe, and configured to
exchange heat between the refrigerant and the heat medium; a heat
medium flow switching device configured to switch combinations of
connection between each of the use-side units and a corresponding
one of the intermediate heat exchangers; a target determination
device configured to detect a condensation state of each of the
use-side units and determine whether to perform condensation
suppression control for suppressing condensation with respect to
each of the use-side units; a temperature sensor configured to
detect, as a heat medium temperature, a temperature of the heat
medium flowing into at least one use-side unit of the use-side
units determined by the target determination device to be subjected
to the condensation suppression control; a heat medium circuit
control device configured to control the heat medium flow switching
device so as to connect the at least one use-side unit of the
use-side units determined by the target determination device to be
subjected to the condensation suppression control to an
intermediate heat exchanger for adjustment assigned for the
condensation suppression control among the plurality of
intermediate heat exchangers; and a refrigerant circuit control
device configured to control a temperature of the refrigerant
flowing into the intermediate heat exchanger for adjustment so that
the heat medium temperature detected by the temperature sensor
falls within a predetermined target set temperature range.
2. The air-conditioning apparatus of claim 1, further comprising a
refrigerant expansion device configured to expand or depressurize
the refrigerant flowing into the intermediate heat exchanger for
adjustment, wherein the refrigerant circuit control device controls
the temperature of the refrigerant by controlling an amount of
expansion of the refrigerant expansion device.
3. The air-conditioning apparatus of claim 2, wherein the
refrigerant circuit control device controls the refrigerant
expansion device so as to keep the heat medium temperature within
the target set temperature range, when the heat medium temperature
is within the target set temperature range.
4. The air-conditioning apparatus of claim 1, wherein the heat
source-side unit is configured to perform a heating operation and a
cooling operation, the air-conditioning apparatus further comprises
a refrigerant flow switching device configured to switch a flow
path of the refrigerant flowing into the intermediate heat
exchanger for adjustment to a heating flow path for the heating
operation and to a cooling flow path for the cooling operation, and
the refrigerant circuit control device controls the temperature of
the refrigerant flowing into the intermediate heat exchanger for
adjustment by causing the refrigerant flow switching device to
switch the flow path of the intermediate heat exchanger for
adjustment.
5. The air-conditioning apparatus of claim 4, wherein the
refrigerant circuit control device causes the refrigerant flow
switching device to set the flow path of the refrigerant flowing
into the intermediate heat exchanger for adjustment to the heating
flow path when the heat medium temperature is lower than the target
set temperature range.
6. The air-conditioning apparatus of claim 4, wherein the
refrigerant circuit control device causes the refrigerant flow
switching device to set the flow path of the refrigerant flowing
into the intermediate heat exchanger for adjustment to the cooling
flow path when the heat medium temperature is higher than the
target set temperature range.
7. The air-conditioning apparatus of claim 1, further comprising:
an inlet temperature sensor configured to detect a temperature of
air sucked into each of the use-side units; and an inlet humidity
sensor configured to detect humidity of the air sucked into each of
the use-side units, wherein the target determination device detects
the condensation status on a basis of the inlet temperature
detected by the inlet temperature sensor and the inlet humidity
detected by the inlet humidity sensor, so as to determine whether
to perform the condensation suppression control.
8. The air-conditioning apparatus of claim 1, further comprising:
an inlet temperature sensor configured to detect a temperature of
air sucked into each of the use-side unit; an inlet humidity sensor
configured to detect humidity of the air sucked into each of the
use-side unit; and a dew point calculation device configured to
calculate a dew point on a basis of the inlet temperature detected
by the inlet temperature sensor and the inlet humidity detected by
the inlet humidity sensor, wherein the refrigerant circuit control
device sets the predetermined target set temperature range on a
basis of the dew point calculated by the dew point calculation
device.
9. The air-conditioning apparatus of claim 8, wherein the
refrigerant circuit control device detects a maximum dew point
which is a highest dew point among the dew points of the at least
one use-side unit of the use-side units determined to be subjected
to the condensation suppression control, and sets the predetermined
target set temperature range on a basis of the detected maximum dew
point.
10. The air-conditioning apparatus of claim 1, further comprising:
a flow rate control device configured to control a flow rate of the
heat medium flowing through the intermediate heat exchanger for
adjustment and the use-side units, wherein the heat medium circuit
control device is configured to control the flow rate control
device, and controls the flow rate control device so that the heat
medium temperature falls within the predetermined target set
temperature range.
Description
TECHNICAL FIELD
[0001] The present invention relates to an air-conditioning
apparatus capable of performing an air-conditioning operation
utilizing cold water or hot water generated from a heat pump cycle
(refrigeration cycle).
BACKGROUND ART
[0002] Air-conditioning apparatuses have been proposed that include
a heat pump cycle in which heat exchange is performed between a
refrigerant and water, and are configured to transport the cold
water or hot water to the indoor side for air conditioning, thereby
preventing leakage of the refrigerant and contributing to reducing
CFCs emission. In some of such apparatuses, a water heat exchanger
is adopted in the air-conditioning refrigerant system composed of a
compressor, an outdoor heat exchanger, an expansion device, an
indoor heat exchanger, and an accumulator, and cold water or hot
water generated in the water heat exchanger is transported by a
pump and a valve so as to perform both cooling operation and
heating operation at the same time, for example as disclosed in
Patent Literature 1. In the air-conditioning apparatus according to
Patent Literature 1, a unit including the refrigerant-water heat
exchanger, and a water-based indoor unit are connected to the heat
source unit, to thereby enable water-based air conditioning,
despite being designed as a multi-air-conditioning apparatus for
building.
CITATION LIST
Patent Literature
[0003] Patent Literature 1: International Publication No.
2010/049998 (FIG. 3)
SUMMARY OF INVENTION
Technical Problem
[0004] However, in the case where water is used as the transport
fluid for exchanging heat with air as proposed in Patent Literature
1, condensation is prone to take place because of higher specific
heat. In particular, in the case where some of the indoor units
performing the cooling operation are only designed for natural
convection (for example, chilled beam), the temperature of the
entirety of such indoor units drops and hence condensation often
takes place, because the heat exchange amount by natural convection
is small. Accordingly, it is preferable to suppress the
condensation with respect to each individual indoor unit, when the
system includes a plurality of indoor units as in Patent Literature
1. However, it is technically difficult to perform the control for
suppressing the condensation with respect to each individual indoor
unit.
[0005] The present invention has been accomplished in view of the
foregoing problem, and provides an air-conditioning apparatus
capable of independently performing condensation suppression
control with respect to each of use-side units that are likely to
suffer condensation, out of a plurality of use-side units.
Solution to Problem
[0006] In an aspect, the present invention provides an
air-conditioning apparatus that includes a heat source-side unit
including a compressor that compresses a refrigerant and a heat
source-side heat exchanger that exchanges heat between air and the
refrigerant, a plurality of use-side units each including a
use-side heat exchanger that exchanges heat between air and a heat
medium, a plurality of intermediate heat exchangers connected to
the heat source-side unit via a refrigerant pipe and connected to
the use-side units via a heat medium pipe, and configured to
exchange heat between the refrigerant and the heat medium, a heat
medium flow switching device configured to switch combinations of
connection between each of the use-side units and a corresponding
one of the intermediate heat exchangers, condensation means
configured to detect a condensation state of each of the use-side
units, target determination means that determine whether to perform
condensation suppression control for suppressing condensation with
respect to each of the use-side units according to the condensation
status detected by the condensation means, temperature means
configured to detect, as a heat medium temperature, a temperature
of the heat medium flowing into at least one use-side unit of the
use-side units determined by the target determination means to be
subjected to the condensation suppression control, heat medium
circuit control means configured to control the heat medium flow
switching device so as to connect the at least one use-side unit of
the use-side units determined by the target determination means to
be subjected to the condensation suppression control to an
intermediate heat exchanger for adjustment assigned for the
condensation suppression control among the plurality of
intermediate heat exchangers, and refrigerant circuit control means
configured to control a temperature of the refrigerant flowing into
the intermediate heat exchanger for adjustment so that the heat
medium temperature detected by the temperature detection means
falls within a predetermined target set temperature range.
Advantageous Effects of Invention
[0007] The air-conditioning apparatus according to the present
invention raises the temperature of the heat medium using the
intermediate heat exchanger for adjustment when one or more of the
plurality of use-side units have condensation or are likely to
suffer condensation, and provides the heat medium to the use-side
heat exchanger to thereby suppress the condensation. Such an
arrangement enables suppression of condensation with respect to a
specific use-side unit, without the need to suspend the normal
operation of the remaining use-side units.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a circuit diagram showing a configuration of an
air-conditioning apparatus 100 according to Embodiment 1 of the
present invention.
[0009] FIG. 2 is a block diagram showing an example of the use-side
unit control means shown in FIG. 1.
[0010] FIG. 3 is a block diagram showing an example of the
intermediate unit control means shown in FIG. 1.
[0011] FIG. 4 is a control flowchart of condensation suppression
control performed by the use-side unit control means of the
air-conditioning apparatus 100 according to Embodiment 1 of the
present invention.
[0012] FIG. 5 is a control flowchart of condensation suppression
control performed by the intermediate unit control means of the
air-conditioning apparatus 100 according to Embodiment 1 of the
present invention.
DESCRIPTION OF EMBODIMENTS
Embodiment 1
Configuration of Air-Conditioning Apparatus
[0013] FIG. 1 is a circuit diagram showing a configuration of an
air-conditioning apparatus 100 according to Embodiment 1 of the
present invention. The air-conditioning apparatus 100 shown in FIG.
1 is designed to be installed in a building, a condominium, a
hotel, and the like, and to provide a cooling load and a heating
load utilizing a heat pump cycle (refrigeration cycle) in which a
refrigerant is circulated. The air-conditioning apparatus 100
adopts a system to indirectly utilize a heat source-side
refrigerant. Specifically, the air-conditioning apparatus 100
transmits cooling energy or heating energy stored in the heat
source-side refrigerant to a heat medium flowing in a circuit
different from a circuit for the heat source-side refrigerant, to
thereby cool or heat an air-conditioned space with the cooling
energy or the heating energy transmitted to the heat medium.
[0014] The air-conditioning apparatus 100 includes one heat source
unit 1 serving as a heat source device, a plurality of use-side
units (indoor units) 2a, 2b, and an intermediate unit 3. The heat
source unit 1 and the intermediate unit 3 are connected to each
other via a refrigerant pipe (high-pressure main pipe 5a and
low-pressure main pipe 5b), and the use-side units 2a, 2b are each
connected to the intermediate unit 3 via a heat medium pipe. The
cooling energy or the heating energy generated in the heat source
unit 1 is transmitted to the use-side units 2a, 2b through the
intermediate unit 3.
[0015] The heat source unit 1 is installed in a space outside of
the building, for example on the roof thereof, and serves to
provide the use-side units 2a, 2b with the cooling energy or the
heating energy through the intermediate unit 3. Here, it is not
mandatory that the heat source unit 1 be installed in a space
outside of the building. For example, the heat source unit 1 may be
installed in a surrounded space such as a machine room with a
ventilation port, or inside of the building provided that waste
heat can be discharged out of the building through an exhaust duct.
Further, in the case of employing a water-cooling heat source unit
1, the heat source unit 1 may be installed inside of the building.
Installing the heat source unit 1 in the cited locations will not
incur particular inconvenience.
[0016] The use-side units 2a, 2b are, for example, indoor units of
a ceiling cassette type, and installed in a position appropriate to
supply cooling air or heating air to an air-conditioned space
located inside the building, to provide the air-conditioned space
with the cooling air or the heating air.
[0017] Here, the use-side units 2a, 2b are not limited to the
ceiling cassette type, but may be recessed in the ceiling or
suspended from the ceiling, or installed in any desired manner
provided that the heating air or the cooling air can be blown into
the air-conditioned space directly or via a duct or the like. In
addition, although two use-side units 2a, 2b are shown in FIG. 1,
three or more use-side units may be provided in the
air-conditioning apparatus 100.
[0018] The intermediate unit 3 serves to transmit the cooling
energy or the heating energy supplied from the heat source unit 1
to the use-side units 2a, 2b, by exchanging heat between the
refrigerant flowing in a refrigerant circuit A on the side of the
heat source unit 1 and the heat medium flowing in a heat medium
circuit B on the side of the use-side units 2a, 2b. The
intermediate unit 3 is installed in a casing independent from that
of the heat source unit 1 and the use-side units 2a, 2b, so as to
be placed at a position different from the outer space and the
air-conditioned space. The intermediate unit 3 is connected to the
heat source unit 1 via a high-pressure main pipe 5a and a
low-pressure main pipe 5b, and to the use-side units 2a, 2b via
heat medium pipes 27, 28, respectively.
(Configuration of Heat Source Unit 1)
[0019] The heat source unit 1 includes a compressor 10, a first
refrigerant flow switching device 11, a heat source-side heat
exchanger 12, and an accumulator 19, which are serially connected
via a refrigerant pipe. The heat source unit 1 also includes heat
source unit control means 51 that controls the frequency of the
compressor 10 and flow path switching of the first refrigerant flow
switching device 11. The compressor 10 sucks a refrigerant in a gas
phase and compresses the refrigerant to increase the temperature
and pressure thereof. The compressor 10 may be of a reciprocating,
a rotary, a scroll, or a screw type, and may preferably include an
inverter for controlling the capacity.
[0020] The first refrigerant flow switching device 11 includes a
four-way valve for example, and serves to switch a refrigerant flow
path according to a required operation mode. More specifically, the
first refrigerant flow switching device 11 switches between a
refrigerant flow path (heating flow path) used in a heating
operation (heating-only operation mode and heating-main operation
mode to be subsequently described) and the other refrigerant flow
path (cooling flow path) used in a cooling operation (cooling-only
operation and cooling-main operation mode to be subsequently
described).
[0021] The heat source-side heat exchanger 12 exchanges heat
between air supplied from an air-sending device 12a and the
refrigerant, and serves as an evaporator in the heating operation
and as a radiator (gas cooler) in the cooling operation. Although
the heat source-side heat exchanger 12 of Embodiment 1 is an air
heat exchanger which exchanges heat with the air supplied from the
air-sending device 12a, the heat source-side heat exchanger 12 is
not limited thereto; the heat source-side heat exchanger 12 may be
a water heat exchanger which utilizes water or brine as heat
source.
[0022] The accumulator 19 is provided on the suction side of the
compressor 10, and serves to accumulate a surplus refrigerant
generated from a difference between the heating operation and the
cooling operation, or from a transition of an operation condition,
such as a change in number of indoor units in operation.
[0023] The heat source unit 1 further includes a flow path
provision section 13 composed of a first joint pipe 4a, a second
joint pipe 4b, and check valves 13a to 13d. The first joint pipe 4a
connects, in the heat source unit 1, a refrigerant pipe connecting
between the first refrigerant flow switching device 11 and the
check valve 13d to be subsequently described, to a refrigerant pipe
connecting between the high-pressure main pipe 5a through which the
refrigerant flows out of the heat source unit 1 and the check valve
13a to be subsequently described. The second joint pipe 4b
connects, in the heat source unit 1, a refrigerant pipe connecting
between the low-pressure main pipe 5b through which the refrigerant
flows into the heat source unit 1 and the check valve 13d to be
subsequently described, to a refrigerant pipe connecting between
the heat source-side heat exchanger 12 and the check valve 13a to
be subsequently described. Forming the flow path provision section
13 thus configured allows the refrigerant directed to the
intermediate unit 3 through the high-pressure main pipe 5a and the
low-pressure main pipe 5b to flow in a constant direction,
irrespective of the operation mode required by the use-side units
2a, 2b.
[0024] The check valve 13a is provided in the refrigerant pipe
connecting between the heat source-side heat exchanger 12 and the
high-pressure main pipe 5a through which the refrigerant flows out
of the heat source unit 1, and allows the refrigerant to flow only
in the direction from the heat source-side heat exchanger 12 toward
the intermediate unit 3. The check valve 13b is provided in the
first joint pipe 4a, and allows the refrigerant discharged from the
compressor 10 to flow only in the direction toward the intermediate
unit 3, in the heating operation. The check valve 13c is provided
in the second joint pipe 4b, and allows the refrigerant that has
returned from the intermediate unit 3 to flow only in the direction
toward the heat source-side heat exchanger 12, in the heating
operation. The check valve 13d is provided in the refrigerant pipe
connecting between the first refrigerant flow switching device 11
and the low-pressure main pipe 5b through which the refrigerant
flows into the heat source unit 1, and allows the refrigerant to
flow only in the direction from the low-pressure main pipe 5b
toward the first refrigerant flow switching device 11.
(Configuration of Use-Side Units 2a, 2b)
[0025] The plurality of use-side units 2a, 2b respectively include
use-side heat exchangers 26a, 26b, inlet temperature sensors 32a,
32b, and inlet humidity sensors 33a, 33b. Further, the use-side
units 2a, 2b respectively include use-side unit control means 52a,
52b, configured to receive inlet temperature information detected
by the inlet temperature sensors 32a, 32b and inlet humidity
information detected by the inlet humidity sensors 33a, 33b, and to
perform arithmetic operation on the basis of such information.
[0026] The use-side heat exchangers 26a, 26b are each connected to
the heat medium pipe 27 through which the heat medium from the
intermediate unit 3 flows, and the heat medium pipe 28 through
which the heat medium from the use-side units 2 flows. The use-side
heat exchangers 26a, 26b serve as radiators (gas coolers) in the
heating operation, and as heat removers in the cooling operation.
The use-side heat exchangers 26a, 26b exchange heat between indoor
air supplied from a non-illustrated air-sending device such as a
fan and the heat medium to thereby provide the air with cooling
energy or heating energy, thus generating heating air or cooling
air provided to the air-conditioned space. Here, although the
use-side heat exchangers 26a, 26b are configured to receive the air
supplied by a fan or the like in Embodiment 1, the use-side heat
exchangers 26a, 26b may be coil-shaped heat exchangers with a wide
fin pitch installed in a ceiling to utilize natural convection,
generally known as a chilled beam.
(Configuration of Intermediate Unit 3)
[0027] The intermediate unit 3 includes an expansion device 9, a
plurality of intermediate heat exchangers 15a, 15b, a plurality of
refrigerant expansion devices 16a, 16b, a liquid refrigerant supply
valve 17a, a gas refrigerant supply valve 17b, second refrigerant
flow switching devices 18a, 18b, pumps 21a, 21b, secondary-side
flow switching devices 22a, 22b, primary-side flow switching
devices 23a, 23b, and heat medium control valves 25a, 25b.
[0028] The intermediate heat exchangers 15a, 15b each serve to
exchange heat between the refrigerant and the heat medium, so as to
transmit cooling energy or heating energy generated in the heat
source unit 1 and stored in the refrigerant to the heat medium. The
intermediate heat exchanger 15a is provided between the refrigerant
expansion device 16a and the second refrigerant flow switching
device 18a in the refrigerant circuit A. The intermediate heat
exchanger 15b is provided between the refrigerant expansion device
16b and the second refrigerant flow switching device 18b in the
refrigerant circuit A.
[0029] The refrigerant expansion devices 16a, 16b are each
constituted of an electronic expansion valve capable of variably
controlling the amount of expansion, and serve as an
expansion/depressurizing valve in the refrigerant circuit A to
expand and depressurize the refrigerant. The expansion device 16a
has an end connected to the intermediate heat exchanger 15a and the
other end connected to the liquid refrigerant supply valve 17a. The
expansion device 16b has an end connected to the intermediate heat
exchanger 15b and the other end connected to the liquid refrigerant
supply valve 17a.
[0030] The intermediate heat exchangers 15a, 15b can set the heat
medium to different temperatures, through control of the expansion
devices 16a, 16b. For example, to make the temperature of the heat
medium generated by the intermediate heat exchanger 15b higher than
the temperature of the heat medium generated by the intermediate
heat exchanger 15a, the expansion device 16b on the side of the
intermediate heat exchanger 15b is made narrower than the expansion
device 16a on the side of the intermediate heat exchanger 15a. In
this case, the temperature of the refrigerant flowing into the
intermediate heat exchanger 15b becomes higher than the temperature
of the refrigerant flowing into the intermediate heat exchanger
15a, and therefore the temperature of the heat medium generated by
the intermediate heat exchanger 15b becomes higher. Likewise, the
temperature of the heat medium generated by the intermediate heat
exchanger 15b can also be made higher than the temperature of the
heat medium generated by the intermediate heat exchanger 15a. Thus,
the refrigerant expansion devices 16a, 16b allow generation of the
heat medium of different temperatures, despite the operation status
being kept unchanged.
[0031] The liquid refrigerant supply valve 17a and the gas
refrigerant supply valve 17b are for example two-way valves, and
serve to open and close the refrigerant pipe in the refrigerant
circuit A. The liquid refrigerant supply valve 17a has an end
connected to the high-pressure main pipe 5a through which the
refrigerant flows into the intermediate unit 3, and the other end
connected to the expansion devices 16a, 16b. The gas refrigerant
supply valve 17b has an end connected to the high-pressure main
pipe 5a through which the refrigerant flows into the intermediate
unit 3, and the other end connected to the second refrigerant flow
switching devices 18a, 18b. The liquid refrigerant supply valve 17a
and the gas refrigerant supply valve 17b may be selected according
to the amount of the refrigerant flowing through the valve and the
purpose thereof and, for example, a four-way valve may be employed
in the case where each of the valves is controlled so as to open
and close in different timings.
[0032] The second refrigerant flow switching devices 18a, 18b are
each constituted of a four-way valve, and serve to switch the flow
direction of the refrigerant according to the operation mode. More
specifically, when the intermediate heat exchanger 15a serves as a
radiator (the refrigerant radiates heat to the heat refrigerant),
the second refrigerant flow switching device 18a is switched to a
heating flow path which causes the high-temperature/high-pressure
refrigerant coming through the gas refrigerant supply valve 17b to
flow into the refrigerant flow path of the intermediate heat
exchanger 15a. When the intermediate heat exchanger 15a serves as
an evaporator (the refrigerant removes heat from the heat
refrigerant), the second refrigerant flow switching device 18a is
switched to a cooling flow path that causes the refrigerant flowing
out of the refrigerant flow path of the intermediate heat exchanger
15a to flow toward the low-pressure main pipe 5b. Likewise, when
the intermediate heat exchanger 15b serves as a radiator (the
refrigerant radiates heat to water), the second refrigerant flow
switching device 18b is switched to a heating flow path which
causes the high-temperature/high-pressure refrigerant coming
through the liquid refrigerant supply valve 17b to flow into the
refrigerant flow path of the intermediate heat exchanger 15b. When
the intermediate heat exchanger 15b serves as an evaporator (the
refrigerant removes heat from water), the second refrigerant flow
switching device 18b is switched to a cooling flow path that causes
the refrigerant flowing out of the refrigerant flow path of the
intermediate heat exchanger 15b to flow toward the low-pressure
main pipe 5b.
[0033] The second refrigerant flow switching device 18a and the
second refrigerant flow switching device 18b are configured to
switch the refrigerant flow to different flow paths. For example,
when the intermediate heat exchanger 15a generates a cooled heat
medium and the intermediate heat exchanger 15b generates a heat
medium higher in temperature than the heat medium of the
intermediate heat exchanger 15a, the second refrigerant flow
switching device 18a switches the flow path to the cooling flow
path, and the second refrigerant flow switching device 18b switches
to the heating flow path. Likewise, the temperature of the heat
medium generated by the intermediate heat exchanger 15b can also be
made higher than the temperature of the heat medium generated by
the intermediate heat exchanger 15a. Thus, the intermediate heat
exchangers 15a, 15b can be caused to generate the heat medium of
different temperatures, by controlling the second refrigerant flow
switching devices 18a, 18b.
[0034] The expansion device 9 has an end connected to the liquid
refrigerant supply valve 17a and the other end connected to the
low-pressure main pipe 5b in the refrigerant circuit A, and serves
as an expansion/depressurizing valve to expand and depressurize the
refrigerant.
[0035] The pumps 21a, 21b apply pressure to the water so as to
circulate through the heat medium circuit B. The pump 21a is
provided in the heat medium pipe between the intermediate heat
exchanger 15a and the heat medium flow switching devices 22. The
pump 21b is provided in the heat medium pipe between the
intermediate heat exchanger 15b and the heat medium flow switching
devices 22. Preferably, the capacity of the pumps 21a, 21b may be
variably controllable by an inverter, or by the number of the
pumps. In addition, although the pumps 21a, 21b are respectively
provided on the suction side of the intermediate heat exchangers
15a, 15b, the pumps 21a, 21b may be provided on the outlet side of
the intermediate heat exchangers 15a, 15b.
[0036] The heat medium flow switching devices 22, 23 are each
constituted of a three-way valve for example, and serve to switch
the combination of connection between the use-side units 2a, 2b and
the intermediate heat exchangers 15a, 15b. The number of heat
medium flow switching devices 22, 23 is determined in accordance
with the number of use-side units 2a, 2b. The heat medium flow
switching devices 22, 23 each have an end among the three ends
connected to the pump 21a, another end connected to the pump 21b,
and the remaining end connected to the flow rate control means
25.
[0037] The primary-side flow switching devices 23 are each
constituted of a three-way valve for example, and serve to switch
the water flow path in the heat medium circuit B, according to the
operation mode. The number of the primary-side flow switching
devices 23 is determined in accordance with the number of use-side
units 2 (two in FIG. 1). In addition, the primary-side flow
switching device 23 has an end among the three ends connected to
the intermediate heat exchanger 15a, another end connected to the
intermediate heat exchanger 15b, and the remaining end connected to
the use-side heat exchangers 26.
[0038] The flow rate control means 25a, 25b are constituted of a
two-way valve with variable aperture area, and have an end
connected to the use-side heat exchangers 26 of the use-side units
2 and the other end connected to the secondary-side flow switching
devices 22. The flow rate control means 25a, 25b serve to control
the flow rate of the heat medium flowing through the use-side heat
exchangers 26a, 26b, respectively. Although the flow rate control
means 25a, 25b are provided in the heat medium pipe system on the
outlet side of the use-side heat exchangers 26a, 26b in FIG. 1, the
configuration is not limited thereto, the flow rate control means
25a, 25b may be provided in the heat medium pipe system on the
inlet side of the use-side heat exchangers 26a, 26b (e.g., on the
outlet side of the primary-side flow switching devices 23a,
23b).
[0039] The intermediate unit 3 also includes heat medium
temperature sensors 31a, 31b, outlet water temperature sensors 34a,
34b, first refrigerant temperature sensors 35a, 35b, pressure
sensors 36a, 36b, and second refrigerant temperature sensors 37a,
37b. Further, the intermediate unit 3 includes intermediate unit
control means 53 that performs arithmetic operations on the basis
of information provided from each of the sensors cited above.
[0040] The temperature sensors 31a, 31b serve to detect the
temperature of the water flowing out of the intermediate heat
exchangers 15a, 15b respectively, in other words the temperature of
the water at the outlet of the flow path of the intermediate heat
exchangers 15, and may be constituted of a thermistor for example.
The temperature sensor 31a is provided in the heat medium pipe on
the outlet side of the intermediate heat exchanger 15a. The
temperature sensor 31b is provided in the heat medium pipe 28 on
the outlet side of the intermediate heat exchanger 15b.
[0041] The outlet water temperature sensor 34a is provided between
the use-side heat exchanger 26a and the flow rate control means 25a
and serves to detect the temperature of the water flowing out of
the use-side heat exchanger 26a, and may be constituted of a
thermistor for example. The number of outlet water temperature
sensors 34 is determined in accordance with the number of use-side
units 2 (two in FIG. 1).
[0042] The first refrigerant temperature sensors 35 are
respectively provided between the intermediate heat exchangers 15
and the second refrigerant flow switching devices 18 to detect the
temperature of the refrigerant flowing into and out of the
intermediate heat exchangers 15, and may be constituted of a
thermistor for example. The first refrigerant temperature sensor
35a is provided between the intermediate heat exchanger 15a and the
second refrigerant flow switching device 18a. The first refrigerant
temperature sensor 35b is provided between the intermediate heat
exchanger 15b and the second refrigerant flow switching device
18b.
[0043] The pressure sensors 36 are, like the first refrigerant
temperature sensors 35, provided between the intermediate heat
exchangers 15 and the second refrigerant flow switching devices
18a, 18b, and serve to detect the pressure of the refrigerant
flowing between the intermediate heat exchangers 15a, 15b and the
refrigerant flow switching devices 18a, 18b. The pressure sensor
36a is provided between the intermediate heat exchanger 15a and the
refrigerant flow switching device 18a. The pressure sensor 36b is
provided between the intermediate heat exchanger 15b and the second
refrigerant flow switching device 18b.
[0044] The second refrigerant temperature sensors 37 are
respectively provided between the intermediate heat exchangers 15
and the expansion devices 16 to detect the temperature of the
refrigerant flowing into and out of the intermediate heat
exchangers 15, and may be constituted of a thermistor for example.
The second refrigerant temperature sensor 37a is provided between
the intermediate heat exchanger 15a and the expansion device 16a.
The second refrigerant temperature sensor 37b is provided between
the intermediate heat exchanger 15b and the expansion device
16b.
[0045] Now, the air-conditioning apparatus 100 includes the
refrigerant circuit A and the heat medium circuit B, and the heat
exchange is performed between the refrigerant circulating in the
refrigerant circuit A through the intermediate heat exchangers 15a,
15b and the water circulating in the heat medium circuit B.
[0046] Specifically, the refrigerant circuit A is composed of the
compressor 10, the first refrigerant flow switching device 11, the
heat source-side heat exchanger 12, the flow path provision section
13, the accumulator 19, the liquid refrigerant supply valve 17a,
the gas refrigerant supply valve 17b, the second refrigerant flow
switching devices 18a, 18b, the refrigerant flow path in the
intermediate heat exchangers 15a, 15b, the expansion devices 16a,
16b, and the expansion device 9, which are connected via the
refrigerant pipe.
[0047] Although the refrigerant circulating in the refrigerant
circuit A is not specifically limited, non-azeotropic refrigerant
mixtures, near-azeotropic refrigerant mixtures, single
refrigerants, and natural refrigerants are applicable to the
refrigeration cycle of the air-conditioning apparatus 100 according
to Embodiment 1. Examples of the non-azeotropic refrigerant mixture
include R407C (R32/R125/R134a) which is a hydro fluorocarbon (HFC)
refrigerant. The non-azeotropic refrigerant mixture is a mixture of
refrigerants having different boiling points, and hence has
different composition ratios between liquid-phase refrigerants and
gas-phase refrigerants. Examples of the near-azeotropic refrigerant
mixture include R410A (R32/R125) and R404A (R125/R143a/R134a) which
are HFC refrigerants. The near-azeotropic refrigerant mixture has a
characteristic similar to that of the non-azeotropic refrigerant
mixture and, in addition, provides a working pressure approximately
1.6 times higher than the pressure of R22. Examples of the single
refrigerant include R22 which is a hydrochlorofluorocarbon (HCFC)
refrigerant, and R134a which is a HFC refrigerant. The single
refrigerant is easy to handle, because of not being a mixture.
Examples of the natural refrigerant include carbon dioxide,
propane, isobutane, and ammonium. Here, R22 represents
chlorodifluoromethane, R32 represents difluoromethane, R125
represents pentafluoromethane, R134a represents
1,1,1,2-tetrafluoromethane, and R143a represents
1,1,1-trifluoroethane. Therefore, it is preferable to employ a
suitable refrigerant according to the purpose and the condition of
use of the air-conditioning apparatus 100.
[0048] On the other hand, the flow paths of the intermediate heat
exchangers 15a, 15b, the pumps 21a, 21b, the secondary-side flow
switching devices 22a, 22b, the flow rate control means 25a, 25b,
the use-side heat exchangers 26a, 26b, and the primary-side flow
switching devices 23a, 23b are connected via the heat medium pipe,
thus constituting the heat medium circuit B.
[0049] For example, water or brine (antifreeze solution) may be
employed as the heat medium circulating in the heat medium circuit
B. The type of the antifreeze agent of the antifreeze solution is
not specifically limited, but preferably ethyleneglycol,
propyleneglycol, or the like may be adopted according to the
purpose of use. Since the cited heat media have high level of
safety, there is little likelihood that harm or trouble is incurred
even though the heat medium leaks out of the use-side units 2a, 2b
into the air-conditioned space.
[0050] Hereunder, description will be given on the operation modes
performed by the air-conditioning apparatus 100 shown in FIG. 1.
The air-conditioning apparatus 100 is configured to receive an
instruction from each of the use-side units 2a, 2b and to cause the
corresponding use-side units 2a, 2b to perform a cooling operation
or heating operation. Further, the air-conditioning apparatus 100
is configured to cause both of the use-side units 2a, 2b to perform
the same operation, or allow each of the use-side units 2 to
perform a different operation.
[0051] The operation modes that the air-conditioning apparatus 100
is configured to perform include a cooling-only operation mode in
which all of the use-side units 2 perform the cooling operation, a
heating-only operation mode in which all of the use-side units 2
perform the heating operation, a cooling-main operation mode in
which the cooling load is larger, and a heating-main operation mode
in which the heating load is larger. Each of the mentioned
operation modes will described hereunder, along with the flow of
the refrigerant and the water.
(Cooling-Only Operation Mode)
[0052] In the cooling-only operation mode, on the side of the
refrigerant circuit A the refrigerant flow path is switched by the
first refrigerant flow switching device 11 so as to cause the
refrigerant discharged from the compressor 10 to flow into the heat
source-side heat exchanger 12. In addition, in the intermediate
unit 3 the liquid refrigerant supply valve 17a is opened and the
gas refrigerant supply valve 17b is closed. Further, the second
refrigerant flow switching devices 18a, 18b respectively set the
cooling flow paths that cause the refrigerant flowing out of the
refrigerant flow path in the intermediate heat exchangers 15a, 15b
to flow toward the low-pressure main pipe 5b. On the side of the
heat medium circuit B, on the other hand, the pumps 21a, 21b are
activated and the flow rate control means 25a, 25b are opened so as
to cause the heat medium to circulate between the intermediate heat
exchangers 15a, 15b and the use-side heat exchangers 26a, 26b,
respectively, in the intermediate unit 3.
[0053] Referring first to FIG. 1, the flow of the refrigerant in
the refrigerant circuit A will be described. The
low-temperature/low-pressure gas refrigerant is compressed by the
compressor 10 and discharged in the state of the
high-temperature/high-pressure refrigerant. The
high-temperature/high-pressure refrigerant discharged from the
compressor 10 passes through the first refrigerant flow switching
device 11 and flows into the heat source-side heat exchanger 12
which serves as a condenser. The high-temperature/high-pressure gas
refrigerant is condensed through heat exchange with outside air
while passing through the heat source-side heat exchanger 12, and
turns into a high-pressure liquid refrigerant. Thus, the
high-temperature/high-pressure refrigerant turns into the
high-pressure refrigerant by radiating heat to the outdoor air, and
flows out of the heat source unit 1 through the check valve 13a.
Then the high-pressure refrigerant flows into the intermediate unit
3 through the high-pressure main pipe 5a.
[0054] The high-pressure refrigerant which has entered the
intermediate unit 3 is branched after passing through the liquid
refrigerant supply valve 17a, and flows into the expansion devices
16a, 16b. The high-pressure heat medium is expanded and
depressurized in the expansion devices 16a, 16b, thus to turn into
a low-temperature/low-pressure gas-liquid two-phase refrigerant.
The gas-liquid two-phase refrigerant flows into each of the
intermediate heat exchangers 15a, 15b which serve as evaporators,
and cools the heat medium circulating in the heat medium circuit B
by removing heat from that heat medium, by which the two-phase
refrigerant is evaporated thus to turn into the
low-temperature/low-pressure gas refrigerant. The gas refrigerant
which flows out from each of the intermediate heat exchangers 15a,
15b joins after respectively passing through the second refrigerant
flow switching devices 18a, 18b, and flows out of the intermediate
unit 3. The gas refrigerant then passes through the low-pressure
main pipe 5b and again flows into the heat source unit 1. The gas
refrigerant which has entered heat source unit 1 passes through the
check valve 13d, the first refrigerant flow switching device 11,
and the accumulator 19, and is again sucked into the compressor
10.
[0055] Still referring to FIG. 1, the flow of the heat medium in
the heat medium circuit B will be described. In the cooling-only
operation mode, the cooling energy of the refrigerant is
transmitted to the heat medium in the intermediate heat exchangers
15a, 15b, and the cooled water is driven by the pumps 21a, 21b to
flow through the heat medium circuit B. The heat medium pressurized
and driven out from the pumps 21a, 21b flows into the intermediate
heat exchangers 15a, 15b respectively, and is cooled by the
refrigerant circulating in the refrigerant circuit A. The heat
medium which has flowed out of the intermediate heat exchanger 15a
is branched halfway and flows out of the intermediate unit 3
through each of the primary-side flow switching devices 23a, 23b,
and then flows into each of the use-side units 2a, 2b. Likewise,
the heat medium which has flowed out of the intermediate heat
exchanger 15b is branched halfway and flows out of the intermediate
unit 3 through each of the primary-side flow switching devices 23a,
23b, and then flows into each of the use-side units 2a, 2b.
[0056] The heat medium which has entered the use-side unit 2a, 2b
flows into the use-side heat exchangers 26a, 26b, respectively, and
cools the air-conditioned space by removing heat from the air in
the air-conditioned space. The heat medium which has flowed out of
the use-side heat exchangers 26a, 26b flows out of the use-side
units 2a, 2b respectively, and flows into the intermediate unit 3
through the heat medium pipe.
[0057] The heat medium which has entered the intermediate unit 3
flows into each of the flow control valves 25a, 25b. At this point,
the heat medium flows into the use-side heat exchangers 26a, 26b at
a flow rate controlled by the flow control valves 25a, 25b so as to
satisfy the air-conditioning load required in the air-conditioned
space. The heat medium which has flowed out of the flow control
valve 25a is branched at the secondary-side flow switching device
22a and sucked into each of the pumps 21a, 21b. The water which has
flowed out of the flow control valve 25b passes through the flow
control valve 25b and is branched at the secondary-side flow
switching device 22b, and then sucked into each of the pumps 21a,
21b.
(Heating-Only Operation Mode)
[0058] In the heating-only operation mode, on the side of the
refrigerant circuit A the refrigerant flow path is switched by the
first refrigerant flow switching device 11 so as to cause the
refrigerant discharged from the compressor 10 to flow into the
intermediate unit 3. In addition, the liquid refrigerant supply
valve 17a is closed and the gas refrigerant supply valve 17b is
opened. Further, the second refrigerant flow switching device 18b
sets the heating flow path that causes the
high-temperature/high-pressure refrigerant flowing from the gas
refrigerant supply valve 17b to flow into the refrigerant flow path
in the intermediate heat exchanger 15b to flow toward the
low-pressure main pipe 5b. On the side of the heat medium circuit
B, the pumps 21a, 21b are activated and the flow rate control means
25a, 25b are opened so as to cause the heat medium to circulate
between the intermediate heat exchangers 15a, 15b and the use-side
heat exchangers 26a, 26b, respectively, in the intermediate unit
3.
[0059] First, the flow of the refrigerant in the refrigerant
circuit A will be described. The low-temperature/low-pressure gas
refrigerant is compressed by the compressor 10 and discharged in
the state of the high-temperature/high-pressure refrigerant. The
high-temperature/high-pressure refrigerant discharged from the
compressor 10 passes through the first refrigerant flow switching
device 11, flows out of the heat source unit 1 through the check
valve 13b in the first joint pipe 4a, and flows into the
intermediate unit 3 through the high-pressure main pipe 5a.
[0060] The high-temperature/high-pressure refrigerant which has
entered the intermediate unit 3 is branched after passing through
the gas refrigerant supply valve 17b, and flows into the
intermediate heat exchangers 15a, 15b, which serve as radiators,
through the second refrigerant flow switching devices 18a, 18b,
respectively. The high-temperature/high-pressure refrigerant which
has entered each of the intermediate heat exchangers 15a, 15b turns
into the high-pressure refrigerant while heating the water by
radiating heat to the refrigerant circulating in the heat medium
circuit B. The high-pressure refrigerant flows out of the
intermediate heat exchangers 15a, 15b and flows into the expansion
devices 16a, 16b respectively, to be expanded and depressurized
thus to turn into the low-temperature/low-pressure gas-liquid
two-phase refrigerant. The gas-liquid two-phase refrigerant joins
and is further expanded and depressurized by the expansion device
9, and then flows out of the intermediate unit 3 and again flows
into the heat source unit 1 through the low-pressure main pipe
5b.
[0061] The gas-liquid two-phase refrigerant which has entered the
heat source unit 1 flows into the heat source-side heat exchanger
12 through the check valve 13c in the second joint pipe 4b, and
vaporizes by removing heat from outdoor air thus to turn into the
low-temperature/low-pressure gas refrigerant, and then again flows
into the compressor 10 through the first refrigerant flow switching
device 11 and the accumulator 19.
[0062] Still referring to FIG. 1, the flow of the heat medium in
the heat medium circuit B will be described. In the heating-only
operation mode, the heating energy of the refrigerant is
transmitted to the water in both of the intermediate heat
exchangers 15a, 15b, and the heated heat medium is driven by the
pumps 21a, 21b to flow through the heat medium circuit B. The heat
medium pressurized and driven out from the pumps 21a, 21b flows
into the intermediate heat exchangers 15a, 15b respectively, and is
heated by the refrigerant circulating in the refrigerant circuit A.
The heat medium which has flowed out of the intermediate heat
exchanger 15a is branched halfway and flows out of the intermediate
unit 3 through each of the primary-side flow switching devices 23a,
23b, and then flows into each of the use-side units 2a, 2b.
Likewise, the heat medium which has flowed out of the intermediate
heat exchanger 15b is branched halfway and flows out of the
intermediate unit 3 through each of the primary-side flow switching
devices 23a, 23b, and then flows into each of the use-side units
2a, 2b.
[0063] The heat medium which has entered the use-side units 2a, 2b
flows into the use-side heat exchangers 26a, 26b, respectively, and
radiates heat to the air in the air-conditioned space, thereby
performing the heating operation for the air-conditioned space.
Then the heat medium which has flowed out of the use-side heat
exchangers 26a, 26b flows out of the use-side units 2a, 2b,
respectively, and flows into the intermediate unit 3 through the
heat medium pipe.
[0064] The heat medium which has entered the intermediate unit 3
flows into each of the flow control valves 25a, 25b. At this point,
the heat medium flows into the use-side heat exchangers 26a, 26b at
a flow rate controlled by the flow control valves 25a, 25b so as to
satisfy the air-conditioning load required in the air-conditioned
space. The heat medium which has flowed out of the flow control
valve 25a passes through the flow control valve 25a and is branched
at the secondary-side flow switching device 22a, and then sucked
into each of the pumps 21a, 21b. The heat medium which has flowed
out of the flow control valve 25b passes through the flow control
valve 25b and is branched at the secondary-side flow switching
device 22b, and then sucked into each of the pumps 21a, 21b.
(Cooling-Main Operation Mode)
[0065] The cooling-main operation mode performed by the
air-conditioning apparatus 100 shown in FIG. 1 will be described
hereunder, on the assumption that a cooling load is required by the
use-side heat exchanger 26a and a heating load is required by the
use-side heat exchanger 26b. Here, in the cooling-main operation
mode the refrigerant flow path is switched by the first refrigerant
flow switching device 11 so as to cause the refrigerant discharged
from the compressor 10 to flow into the heat source-side heat
exchanger 12. In addition, the expansion device 16a is fully
opened, the liquid refrigerant supply valve 17a is opened, and the
gas refrigerant supply valve 17b is opened. Further, in the
intermediate unit 3 the pumps 21a, 21b are activated and the flow
rate control means 25a, 25b are opened, so as to cause the heat
medium to circulate between the intermediate heat exchangers 15a,
15b and the use-side heat exchangers 26a, 26b.
[0066] Referring again to FIG. 1, the flow of the refrigerant in
the refrigerant circuit A will be described.
[0067] The low-temperature/low-pressure gas refrigerant is
compressed by the compressor 10 and discharged in the state of the
high-temperature/high-pressure refrigerant. The
high-temperature/high-pressure refrigerant discharged from the
compressor 10 flows into the heat source-side heat exchanger 12
through the first refrigerant flow switching device 11, turns into
the high-pressure refrigerant having a lowered temperature by
radiating heat to outdoor air, flows out of the heat source unit 1
through the check valve 13a, and flows into the intermediate unit 3
through the high-pressure main pipe 5a.
[0068] The high-pressure refrigerant which has entered the
intermediate unit 3 flows into the intermediate heat exchanger 15b
which serves as a radiator through the gas refrigerant supply valve
17b and the second refrigerant flow switching device 18b. Then the
high-pressure refrigerant radiates heat through the intermediate
heat exchanger 15b to the heat medium circulating in the heat
medium circuit B. Accordingly, the high-pressure refrigerant heats
the heat medium and turns into the high-pressure refrigerant having
a further lowered temperature. The high-pressure refrigerant which
has flowed out of the intermediate heat exchanger 15b is expanded
and depressurized by the expansion device 16b thus turning into the
low-temperature/low-pressure gas-liquid two-phase refrigerant,
flows into the intermediate heat exchanger 15a which serves as an
evaporator through the expansion device 16a, and vaporizes while
cooling the heat medium circulating in the heat medium circuit B by
removing heat from the heat medium, thereby turning into the
low-temperature/low-pressure gas refrigerant. The gas refrigerant
which has flowed out of the intermediate heat exchanger 15a flows
out of the intermediate unit 3 through the second refrigerant flow
switching device 18a, and again flows into the heat source unit 1
through the low-pressure main pipe 5b. The gas refrigerant which
has entered the heat source unit 1 passes through the check valve
13d, the first refrigerant flow switching device 11, and the
accumulator 19, and is again sucked into the compressor 10.
[0069] Still referring to FIG. 1, the flow of the heat medium in
the heat medium circuit B will be described. In the cooling-main
operation mode, the cooling energy of the refrigerant is
transmitted to the heat medium in the intermediate heat exchanger
15a, and the cooled heat medium is driven by the pump 21a to flow
through the heat medium circuit B. In addition, in the cooling-main
operation mode the heating energy of the refrigerant is transmitted
to the heat medium in the intermediate heat exchanger 15b, and the
heated heat medium is driven by the pump 21b to flow through the
heat medium circuit B.
[0070] The heat medium pressurized and driven out from the pump 21a
flows into the intermediate heat exchanger 15a and is cooled by the
refrigerant circulating in the refrigerant circuit A. The heat
medium pressurized and driven out from the pump 21b flows into the
intermediate heat exchanger 15b and is heated by the refrigerant
circulating in the refrigerant circuit A. The heat medium which has
flowed out of the intermediate heat exchanger 15a flows out of the
intermediate unit 3 through the primary-side flow switching device
23a and flows into the use-side unit 2a. The heat medium which has
flowed out of the intermediate heat exchanger 15b flows out of the
intermediate unit 3 through the primary-side flow switching device
23b, and flows into the use-side unit 2b.
[0071] The cooled heat medium which has entered the use-side unit
2a flows into the use-side heat exchanger 26a, while the heated
heat medium which has entered the use-side unit 2b flows into the
use-side heat exchanger 26b. The heat medium which has entered the
use-side heat exchanger 26a removes heat from the air in the
air-conditioned space, thereby cooling the air-conditioned space.
In contrast, the heat medium which has entered the use-side heat
exchanger 26b radiates heat to the air in the air-conditioned
space, thereby heating the air-conditioned space. Then the heat
medium flowing out of the use-side heat exchanger 26a and now
having an increased temperature flows out of the use-side unit 2a
and flows into the intermediate unit 3 through the heat medium
pipes 27, 28. On the other hand, the heat medium flowing out of the
use-side heat exchanger 26b and now having a lower temperature
flows out of the use-side unit 2b and flows into the intermediate
unit 3 through the heat medium pipes 27, 28.
[0072] The heat medium which has entered the intermediate unit 3
from the use-side heat exchanger 26a flows into the flow rate
control means 25a, while the heat medium which has entered the
intermediate unit 3 from the use-side heat exchanger 26b flows into
the flow rate control means 25b. At this point, the heat medium
flows into the use-side heat exchangers 26a, 26b at a flow rate
controlled by the flow control valves 25a, 25b so as to satisfy the
air-conditioning load required in the air-conditioned space. The
heat medium which has flowed out of the flow control valve 25a
passes through the secondary-side flow switching device 22a and is
again sucked into the pump 21a. Likewise, the heat medium which has
flowed out of the flow control valve 25b passes through the
secondary-side flow switching device 22b and is again sucked into
the pump 21b. As described above, in the cooling-main operation
mode the portions of the heat medium set to different temperatures
can be separately supplied, without being mixed with each other, to
the use-side heat exchangers 26 where the cooling load and the
heating load are required, owing to the operation of the
primary-side flow switching devices 23 and the secondary-side flow
switching devices 22.
(Heating-Main Operation Mode)
[0073] The heating-main operation mode performed by the
air-conditioning apparatus 100 shown in FIG. 1 will be described
hereunder, on the assumption that a heating load is required by the
use-side heat exchanger 26a and a cooling load is required by the
use-side heat exchanger 26b. In the heating-main operation mode,
the refrigerant flow path is switched by the first refrigerant flow
switching device 11 so as to cause the refrigerant discharged from
the compressor 10 to flow into the intermediate unit 3 without
passing through the heat source-side heat exchanger 12, in the heat
source unit 1. In addition, the expansion device 16a is fully
opened, the liquid refrigerant supply valve 17a is closed, and the
gas refrigerant supply valve 17b is opened. Further, in the
intermediate unit 3 the pumps 21a, 21b are activated and the flow
rate control means 25a, 25b are opened, so as to cause the heat
medium to circulate between the intermediate heat exchangers 15a,
15b and the use-side heat exchangers 26a, 26b, respectively.
[0074] Referring again to FIG. 1, the flow of the refrigerant in
the refrigerant circuit A will be described. The
low-temperature/low-pressure gas refrigerant is compressed by the
compressor 10 and discharged in the state of the
high-temperature/high-pressure refrigerant. The
high-temperature/high-pressure refrigerant discharged from the
compressor 10 passes through the first refrigerant flow switching
device 11 and flows out of the heat source unit 1 through the check
valve 13b in the first joint pipe 4a, and then flows into the
intermediate unit 3 through the high-pressure main pipe 5a.
[0075] The high-temperature/high-pressure refrigerant which has
entered the intermediate unit 3 flows into the intermediate heat
exchanger 15b which serves as a radiator through the gas
refrigerant supply valve 17b and the second refrigerant flow
switching device 18b, and heats the heat medium circulating in the
heat medium circuit B by radiating heat to the heat medium, thus
turning into the high-pressure refrigerant. The high-pressure
refrigerant which has flowed out of the intermediate heat exchanger
15b is expanded and depressurized by the expansion device 16b thus
turning into the low-temperature/low-pressure gas-liquid two-phase
refrigerant. The low-temperature/low-pressure gas-liquid two-phase
refrigerant flows into the intermediate heat exchanger 15a which
serves as an evaporator through the expansion device 16a, and cools
the heat medium circulating in the heat medium circuit B by
removing heat from the heat medium, thus turning into the
refrigerant having an increased temperature. The refrigerant which
has flowed out of the intermediate heat exchanger 15a flows out of
the intermediate unit 3 through the second refrigerant flow
switching device 18a, and again flows into the heat source unit 1
through the low-pressure main pipe 5b.
[0076] The refrigerant which has entered the heat source unit 1
flows into the heat source-side heat exchanger 12 through the check
valve 13c in the second joint pipe 4b, vaporizes by removing heat
from outdoor air thus turning into the low-temperature/low-pressure
gas refrigerant, and is again sucked into the compressor 10 through
the first refrigerant flow switching device 11 and the accumulator
19.
[0077] Still referring to FIG. 1, the flow of the heat medium in
the heat medium circuit B will be described. In the heating-main
operation mode, the cooling energy of the refrigerant is
transmitted to the heat medium in the intermediate heat exchanger
15a, and the cooled heat medium is driven by the pump 21a to flow
through the heat medium circuit B. In addition, in the heating-main
operation mode the heating energy of the refrigerant is transmitted
to the heat medium in the intermediate heat exchanger 15a, and the
heated heat medium is driven by the pump 21b to flow through the
heat medium circuit B.
[0078] The heat medium pressurized and driven out from the pump 21a
flows into the intermediate heat exchanger 15a and is cooled by the
refrigerant circulating in the refrigerant circuit A. The heat
medium pressurized and driven out from the pump 21b flows into the
intermediate heat exchanger 15b and is heated by the refrigerant
circulating in the refrigerant circuit A. The heat medium which has
flowed out of the intermediate heat exchanger 15a flows out of the
intermediate unit 3 through the primary-side flow switching device
23b and flows into the use-side unit 2b. The heat medium which has
flowed out of the intermediate heat exchanger 15b flows out of the
intermediate unit 3 through the primary-side flow switching device
23a, and flows into the use-side unit 2a.
[0079] The heat medium which has entered the use-side unit 2a flows
into the use-side heat exchanger 26a, while the heat medium which
has entered the use-side unit 2b flows into the use-side heat
exchanger 26b. The heat medium which has entered the use-side heat
exchanger 26a radiates heat to the air in the air-conditioned
space, thereby heating the air-conditioned space. In contrast, the
heat medium which has entered the use-side heat exchanger 26b
removes heat from the air in the air-conditioned space, thereby
cooling the air-conditioned space. Then the heat medium flowing out
of the use-side heat exchanger 26a and now having a lowered
temperature flows out of the use-side unit 2a and flows into the
intermediate unit 3 through the heat medium pipes 27, 28. On the
other hand, the heat medium flowing out of the use-side heat
exchanger 26b and now having an increased temperature flows out of
the use-side unit 2b and flows into the intermediate unit 3 through
the heat medium pipes 27, 28.
[0080] The heat medium which has entered the intermediate unit 3
from the use-side heat exchanger 26a flows into the flow rate
control means 25a, while the heat medium which has entered the
intermediate unit 3 from the use-side heat exchanger 26b flows into
the flow rate control means 25b. At this point, the heat medium
flows into the use-side heat exchangers 26a, 26b at a flow rate
controlled by the flow control valves 25a, 25b so as to satisfy the
air-conditioning load required in the air-conditioned space. The
heat medium which has flowed out of the flow control valve 25a
passes through the secondary-side flow switching device 22a and is
again sucked into the pump 21b. Likewise, the heat medium which has
flowed out of the flow control valve 25b passes through the
secondary-side flow switching device 22b and is again sucked into
the pump 21a. As described above, in the heating-main operation
mode the portions of the heat medium set to different temperatures
can be separately supplied, without being mixed with each other, to
the use-side heat exchangers 26 where the cooling load and the
heating load are required, owing to the operation of the
primary-side flow switching devices 23 and the secondary-side flow
switching devices 22.
[0081] The four operation modes have been described on the
assumption that both of the use-side units 2a, 2b are operated for
cooling or heating. In the case where either of the use-side units
2a, 2b is out of operation, the flow rate control means 25 is
closed, so as not to perform the cooling or heating operation.
(Configuration of Control Device)
[0082] The air-conditioning apparatus 100 shown in FIG. 1 includes
the heat source unit control means 51, the use-side unit control
means 52a, 52b, and the intermediate unit control means 53. The
heat source unit control means 51 is provided in the heat source
unit 1, the use-side unit control means 52a, 52b are respectively
provided in the use-side units 2, and the intermediate unit control
means 53 is provided in the intermediate unit 3. The control means
51 to 53 are communicable with each other via a non-illustrated
communication means (wired or wireless), and configured to control
the corresponding units by exchanging information via the
communication means.
[0083] The control means 51 to 53 are each constituted of a
microcomputer, a digital signal processor (DSP), or the like, and
serve to control the overall operation of the air-conditioning
apparatus 100. The control means 51 to 53 may be set up so as to
perform distributed autonomous cooperative control, to
independently control the respective corresponding units (heat
source unit 1, use-side units 2a, 2b, and intermediate unit 3).
Alternatively, control means may be provided in one of the units,
so as to collectively control the actuator and other components of
each of the units.
[0084] The control means 51 to 53 are configured to perform
condensation suppression control. The condensation suppression
control herein referred to includes determining whether
condensation takes place with respect to each of the use-side units
2a, 2b, and generating, upon determining that the condensation is
taking place or is likely to take place, the heat medium of a
temperature different from the temperature for the normal operation
and supplying such heat medium to the use-side heat exchanger 26a
or 26b of the corresponding use-side unit 2a or 2b. The heat medium
of the different temperature for suppressing condensation is
generated by one or more intermediate heat exchangers for
adjustment 15b among the plurality of intermediate heat exchangers
15a, 15b. Which of the intermediate heat exchangers is designated
as the intermediate heat exchanger for adjustment is determined in
advance in each of the control means 51 to 53.
[0085] The heat source unit control means 51 controls the flow
path, the pressure condition, and the temperature condition of the
refrigerant in the heat source unit 1. More specifically, the heat
source unit control means 51 performs arithmetic operations on the
basis of pressure information and temperature information
respectively detected by a pressure sensor and a temperature sensor
(neither shown), and then controls the frequency of the compressor
10, the fan rotation speed of the air-sending device 12a, the flow
path switching of the first refrigerant flow switching device 11,
and so forth.
[0086] FIG. 2 is a block diagram showing an example of the use-side
unit control means 52a, 52b. Here, it is assumed that the use-side
unit control means 52a, 52b have the same configuration. The
use-side unit control means 52a, 52b serve to perform, mainly, the
condensation suppression control, operation control, and thermostat
control. The use-side unit control means 52a, 52b each include
target identification means 520, target determination means 521,
and dew point calculation means 522, to perform the condensation
suppression control.
[0087] The target identification means 520 stores therein the unit
type information about the use-side units 2a, 2b themselves. The
target determination means 521 determines whether the use-side unit
should undergo the condensation suppression control, on the basis
of the unit type information, the temperature information, and
humidity information. More specifically, the target determination
means 521 determines whether the condensation suppression control
should be performed on the basis of the unit type information about
the use-side units 2a, 2b. In the case, for example, where the
use-side heat exchangers 26a, 26b are designed to utilize natural
convection like a chilled beam, the target determination means 521
determines that the use-side units 2a, 2b are the type of units
that should undergo the condensation suppression control.
[0088] The target determination means 521 also receives inlet
temperature information detected by an inlet temperature sensor 32
and inlet humidity information detected by an inlet humidity sensor
33. The target determination means 521 possesses, for example, a
threshold preset therein, and determines that the unit should
undergo the condensation suppression control in the case where the
inlet temperature information indicates a value lower than the
temperature threshold. Likewise, the target determination means 521
determines that unit should undergo the condensation suppression
control in the case where the inlet humidity information indicates
a value higher than the preset threshold.
[0089] The dew point calculation means 522 calculates a dew point
on the basis of the inlet temperature information detected by the
inlet temperature sensor 32 and the inlet humidity information
detected by the inlet humidity sensor 33. Here, a known method may
be adopted for the calculation of the dew point. For example, a
vapor pressure (=saturated vapor pressure) may be calculated from
relative humidity (absolute humidity) detected by the sensor, and
the dew point may be calculated from the vapor pressure.
[0090] The dew point calculation means 522 outputs dew point
information to the intermediate unit control means 53 when the
target determination means 521 determines that the unit should
undergo the condensation suppression control. Here, the target
determination means 521 may determine whether to perform the
condensation suppression control depending on the dew point
calculated by the dew point calculation means 522, instead of the
temperature information and the humidity information.
[0091] Further, the use-side unit control means 52a, 52b each
include comparative calculation means 523, thermostat determination
means 524, and operation signal transmission means 525 to perform
the operation control and the thermostat control. The operation
signal transmission means 525 outputs an operation signal for
supplying cold water or hot water to the intermediate unit control
means 53, on the basis of operation request information transmitted
from a control panel 526 (or a remote controller) by wired or
wireless communication. The comparative calculation means 523
transmits temperature difference information indicating a
difference between the inlet temperature information detected by
the inlet temperature sensor 32 and set temperature information
transmitted from the control panel 526, to the thermostat
determination means 524. The thermostat determination means 524
determines whether to continue the operation (thermostat ON) or to
suspend the operation (thermostat OFF), and transmits the
thermostat determination information to the intermediate unit
control means 53.
[0092] FIG. 3 is a block diagram showing an example of the
intermediate unit control means 53. The intermediate unit control
means 53 shown in FIG. 3 includes maximum dew point detection means
53a, heat medium circuit control means 53b, and refrigerant circuit
control means 53c. The maximum dew point detection means 53a
detects a maximum dew point Tmax which is a highest temperature
among the dew point information about the use-side units 2a, 2b
acquired from the plurality of use-side unit control means 52a,
52b. The maximum dew point detection means 53a is also configured
to determine whether the dew point information corresponding to
each of the plurality of use-side units 2a, 2b has been acquired.
In the case where the dew point information can be acquired from
neither of the use-side units 2a, 2b, the maximum dew point
detection means 53a finishes the reception of the dew point
information. In contrast, when the dew point information is
received from any of the use-side units 2a, 2b, the maximum dew
point detection means 53a calculates the maximum dew point
information indicating the highest dew point among the dew point
information received.
[0093] The heat medium circuit control means 53b controls the
section constituting the heat medium circuit B in the
refrigerant-intermediate unit 3. The heat medium circuit control
means 53b controls the flow rate in each of the operation modes
described above, on the basis of a heat medium temperature T
detected by the temperature sensors 31a, 31b and outlet water
temperature information detected by an outlet water temperature
sensor 34. In the condensation suppression control, the heat medium
circuit control means 53b controls the primary-side switching
device 23b and the secondary-side switching device 22b so as to
connect the heat medium flow path of all the use-side heat
exchangers 26b that the dew point information of which has been
received to the intermediate heat exchanger for adjustment 15b.
[0094] The refrigerant circuit control means 53c controls the
section constituting the refrigerant circuit A in the
refrigerant-intermediate unit 3. The refrigerant circuit control
means 53c receives refrigerant pressure information detected by
pressure sensors 36a, 36b, and refrigerant temperature information
detected by first refrigerant temperature sensors 35 and second
refrigerant temperature sensors 37a, 37b. The refrigerant circuit
control means 53c outputs an expansion device amount of expansion
instruction, a refrigerant flow path switching instruction, a gas
refrigerant supply valve instruction, and a liquid refrigerant
supply valve instruction to each actuator, on the basis of the
received refrigerant pressure information and the refrigerant
temperature information.
[0095] The refrigerant circuit control means 53c is also configured
to control, in the condensation suppression control, the expansion
device 26b and the second refrigerant flow switching device 18b
connected to the intermediate heat exchanger 15b on the basis of
the maximum dew point Tmax detected by the maximum dew point
detection means 53a and the heat medium temperature T detected by
the temperature sensor 31b.
[0096] Specifically, the refrigerant circuit control means 53c
acquires the maximum dew point Tmax detected by the maximum dew
point detection means 53a. As stated above, the use-side heat
exchanger 26b which has outputted the dew point information is
already connected to the intermediate heat exchanger for adjustment
15b under the control of the heat medium circuit control means 53b.
Accordingly, the refrigerant circuit control means 53c acquires the
temperature T of the heat medium flowing in the intermediate heat
exchanger for adjustment 15b, from the temperature sensor 31b.
[0097] A target temperature setting device 53x of the refrigerant
circuit control means 53c calculates a target water temperature Tt
of the temperature T of the heat medium flowing into the use-side
heat exchanger 26b utilizing the maximum dew point Tmax, through
the following equation (1).
Target water temperature Tt=maximum dew point Tmax+.alpha.
(.alpha.: predetermined temperature) (1)
[0098] Here, .alpha. is a parameter for determination of the flow
path switching at a temperature higher than the maximum dew point
Tmax, so as to assure that condensation is suppressed. Then the
refrigerant circuit control means 53c sets a target set temperature
range Tr using the maximum dew point Tmax as reference, as maximum
dew point Tmax.ltoreq.heat medium temperature T.ltoreq.target water
temperature Tt+.beta. (.beta.: predetermined temperature).
[0099] In the case where "maximum dew point Tmax heat medium
temperature T.ltoreq.target water temperature Tt+.beta. (.beta.:
predetermined temperature)" is satisfied, the refrigerant circuit
control means 53c controls the amount of expansion of the expansion
device 16b according to the difference between the heat medium
temperature T and the target water temperature Tt. Here, .beta. is
a parameter for preventing excessively frequent switching actions
of the flow switching device, thereby preventing switching
malfunction due to insufficient differential pressure and securing
sufficient stability of the refrigerant temperature. Through the
control of the amount of expansion, the refrigerant circuit control
means 53c controls so as to maintain the heat medium temperature T
within the target set temperature range Tr.
[0100] As above, occurrence of condensation can be prevented in
advance while maintaining the operation mode, in the use-side heat
exchanger 26b where maximum dew point Tmax is equal to or lower
than the heat medium temperature T and condensation has not yet
taken place but is likely to take place. When the use-side unit
control means 52b determines that it is not necessary to perform
the condensation suppression control, the control of the amount of
expansion for the condensation suppression control is finished.
[0101] In the case where the heat medium temperature T is lower
than the maximum dew point Tmax (heat medium temperature
T<maximum dew point Tmax), the refrigerant circuit control means
53c controls the second refrigerant flow switching device 18b so as
to set the refrigerant circuit A of the intermediate heat exchanger
for adjustment 15b to the heating flow path. Accordingly, the heat
medium temperature T of the heat medium is increased through heat
exchange with the refrigerant flowing through the heating flow
path. The heat medium temperature T is controlled so as to enter
the target set temperature range Tr. In other words, in the case
where it is determined that condensation is taking place because
the heat medium temperature T is lower than the maximum dew point
max, the intermediate heat exchanger for adjustment 15b is switched
to the heating flow path to thereby promptly remove the
condensation taking place in the use-side heat exchanger 26b. Here,
when the heat medium temperature T increases until entering the
target set temperature range Tr, the mentioned operation may be
continued until the heat medium temperature becomes lower than the
target water temperature+.beta. (described later), or the
intermediate heat exchanger for adjustment 15b may be again
switched to the cooling flow path to perform the control based on
the amount of expansion.
[0102] In the case where the heat medium temperature is higher than
the target water temperature+.beta., the refrigerant circuit
control means 53c determines whether the intermediate heat
exchanger for adjustment 15b is connected to the heating flow path.
In the case where the intermediate heat exchanger for adjustment
15b is connected to the heating flow path, the refrigerant circuit
control means 53c controls the second refrigerant flow switching
device 18b so as to connect the intermediate heat exchanger 15b to
the cooling flow path. Then the refrigerant circuit control means
53c controls the heat medium temperature T so as to enter the
target set temperature range Tr. When the use-side unit control
means 52b determines that it is not necessary to perform the
condensation suppression control, the control of the amount of
expansion for the condensation suppression control is finished.
[0103] Here, the heat medium circuit control means 53b may control
the flow rate of the heat medium on the side of the heat medium
circuit B to enhance the condensation suppression control, in
addition to the condensation suppression control performed by the
refrigerant circuit control means 53c on the side of the
refrigerant circuit A. For example, when the temperature T of the
incoming heat medium is largely deviated from the target set
temperature range Tr, the heat medium circuit control means 53b may
control the flow rate control means 25a, 25b so as to increase the
flow rate of the heat medium flowing out of the intermediate heat
exchanger for adjustment 15b. In contrast, when the temperature T
of the incoming heat medium is slightly deviated from the target
set temperature range Tr, the heat medium circuit control means 53b
may control the flow rate control means 25a, 25b so as to decrease
the flow rate of the heat medium flowing out of the intermediate
heat exchanger for adjustment 15b. Such an operation contributes to
quickening and optimization of the condensation suppression control
to set the temperature T of the incoming heat medium within the
target set temperature range Tr.
[0104] Although the target set temperature range Tr is set as
"maximum dew point Tmax.ltoreq.heat medium temperature
T.ltoreq.target water temperature Tt+.beta." in the foregoing
description, the maximum dew point Tmax may be utilized as it is,
so as to set the target set temperature range Tr as "maximum dew
point Tmax.ltoreq.heat medium temperature T.ltoreq.Tmax+.beta.". In
this case, it is determined whether the heat medium temperature T
is higher than the maximum dew point Tmax+.beta., instead of
whether higher than the target water temperature+.beta..
(Condensation Suppression Control Method of Air-Conditioning
Apparatus 100)
[0105] FIG. 4 is a flowchart of an operation performed by the
use-side unit control means 52 in the condensation suppression
control of the air-conditioning apparatus 100, and FIG. 5 is a
flowchart of an operation performed by the intermediate unit
control means 53 in the condensation suppression control of the
air-conditioning apparatus 100. Referring to FIG. 1 through FIG. 5,
an example of the condensation suppression control method will be
described. Referring first to FIG. 4, description will be given on
the operation performed by the use-side unit control means 52 for
the condensation suppression control.
[0106] The use-side unit control means 52 each receive target
indoor unit determination information from the target
identification means 520, and the inlet temperature information
detected by the inlet temperature sensor 32 and the inlet humidity
information detected by the inlet humidity sensor 33 (step S1). The
target determination means 521 determines, according to the target
indoor unit determination information, whether the flow rate
control means 25 is not closed and out of operation, and whether
the use-side units 2 are not the use-side unit 2 that do not suit
for the condensation suppression control and the use-side units 2
are in the state that requires the condensation suppression control
(step S2). In the case where the use-side units 2 are to be
subjected to the condensation suppression control as result of the
determination, the use-side unit control means 52 calculate the dew
point (step S3), and transmit the dew point to the intermediate
unit control means 53 (step S4). In the case where the condensation
suppression control is not required, the use-side unit control
means 52 finishes the condensation suppression control. The
following description represents the case where the use-side unit
control means 52b outputs the dew point information while the
use-side unit control means 52a does not.
[0107] Referring now to FIG. 5, description will be given on the
operation performed by the intermediate unit control means 53 for
the condensation suppression control. The intermediate unit control
means 53 receives dew point information from the use-side unit
control means 52b (step S11), through steps S21 to S24 described
below. Specifically, the intermediate unit control means 53
receives the dew point information from the intermediate unit
control means 52b (step S21). The intermediate unit control means
53 determines whether the dew point information corresponding to
the use-side units 2 has been received from the use-side unit
control means 52 (step S22).
[0108] In the case where the dew point information corresponding to
either of the use-side units 2a, 2b has not been received as result
of the determination, the intermediate unit control means 53
finishes the reception of the dew point information (step S23).
Meanwhile, in the case where the dew point information
corresponding to the use-side unit 2b has been received, the
intermediate unit control means 53 connects the use-side heat
exchanger 26b of the use-side unit 2b to the intermediate heat
exchanger for adjustment 15b (step S23).
[0109] Then the intermediate unit control means 53 counts the
number of the use-side units 2b that the dew point information of
which has been received (step S12). In the case where 1 or more
units have been counted, the intermediate unit control means 53
calculates the maximum dew point Tmax indicating the highest value
among the dew point information received (step S13). In Embodiment
1, the dew point of the use-side unit 2b is adopted as the maximum
dew point Tmax. The intermediate unit control means 53 then
calculates the target water temperature Tt based on the maximum dew
point Tmax, for the temperature T of the heat medium flowing into
the use-side unit 2b with the foregoing equation (1) (step S14),
and performs the switching control of the refrigerant circuit
according to the heat medium temperature T (step S15).
[0110] Specifically, in the case where it is determined that the
heat medium temperature T is lower than the maximum dew point Tmax
(heat medium temperature<maximum dew point+.beta.), the
intermediate heat exchanger for adjustment 15b is switched from the
cooling flow path to the heating flow path in which hot water is
flowing (step S16). Accordingly, the heat medium that the
temperature of which has been increased by the intermediate heat
exchanger 15a flows into the use-side heat exchanger 26a, so that
the occurrence of condensation can be suppressed.
[0111] In the case where it is determined that "maximum dew point
Tmax.ltoreq.heat medium temperature T.ltoreq.target water
temperature+.beta. (.beta.: predetermined temperature)" is
satisfied, the refrigerant circuit control means 53c controls the
amount of expansion of the expansion device 16b on the basis of the
difference between the heat medium temperature T and the target
water temperature Tt (step S17). As above, occurrence of
condensation can be prevented in advance while maintaining the
operation mode, in the use-side heat exchanger 26b where
condensation has not yet taken place but is likely to take
place.
[0112] In the case where the heat medium temperature is higher than
the target water temperature+.beta. and the heat medium temperature
T is lower than the target water temperature Tt+.beta., the
refrigerant circuit control means 53c determines whether the
intermediate heat exchanger for adjustment 15b is connected to the
heating flow path (step S18). In the case where the intermediate
heat exchanger for adjustment 15b is connected to the heating flow
path, the refrigerant circuit control means 53c controls the second
refrigerant flow switching device 18b so as to connect the
intermediate heat exchanger 15b to the cooling flow path (step
S19).
[0113] The above-mentioned condensation suppression control by the
intermediate unit control means 53 is performed according to a
predetermined schedule, for which the time interval between the
control sessions may be determined to an optimum value according to
the system configuration. Likewise, the predetermined temperature
.alpha. necessary for the calculation of the target water
temperature and the predetermined temperature .beta. necessary for
the comparative calculation of the heat medium temperature T may be
set to optimum values according to the system configuration.
[0114] The configuration according to Embodiment 1 allows removal
or prevention of condensation, in the case where the condensation
has taken place or is likely to take place in the use-side heat
exchangers 26a, 26b, by increasing the temperature of the
refrigerant flowing through the intermediate heat exchanger for
adjustment 15b, without disturbing the operation of the other
use-side heat exchanger 26a. In particular, in the case of
employing heat exchangers that utilize natural convection, such as
a chilled beam, as the use-side heat exchangers 26a, 26b, the
use-side heat exchangers 26a, 26b can only exchange a small amount
of heat. Accordingly, the use-side units 2a, 2b themselves may
suffer condensation in an environment where the dew point in the
air-conditioned space is high. Even in such a case, the
condensation can be removed or prevented, by increasing the
temperature of the refrigerant flowing through the intermediate
heat exchanger for adjustment 15b. Further, even under a
high-sensible heat operation for lowering only the temperature
(sensible heat) while maintaining the moisture in the air of the
air-conditioned space as much as possible, the condensation can be
securely removed or prevented.
[0115] Further, controlling the operation of the intermediate heat
exchanger for adjustment 15b on the basis of the maximum dew point
Tmax as shown in FIG. 5 allows the condensation suppression control
to be performed with respect to the use-side heat exchanger
suffering the worst condensation impact among the plurality of
use-side heat exchangers that require the condensation suppression
control, and therefore condensation can be securely suppressed in
all of the use-side heat exchangers that require the condensation
suppression control. Here, in the case where an appropriate
temperature has been attained in the use-side heat exchangers other
than the use-side heat exchanger 26b having the maximum dew point
Tmax, the primary-side flow switching device 23b and the
primary-side flow switching device 23a may be controlled so as to
return to the normal operation. Still further, since providing at
least one intermediate heat exchanger for adjustment 15b allows the
condensation suppression control to be performed for the plurality
of use-side units, there is no need to generate the heat medium of
different temperatures for each of the use-side heat exchangers,
which enables efficient performance of the condensation suppression
control.
[0116] The present invention is in no way limited to Embodiment 1.
For example, although the use-side units 2a, 2b have the same
configuration in FIG. 1, the use-side units 2a, 2b of different
configurations may be installed. In this case also, the dew point
information is outputted from the use-side units 2a, 2b to the
intermediate unit control means 53 (see FIG. 3), so as to perform
the condensation suppression control.
[0117] In addition, although the temperature means 34a, 34b are
respectively provided for the intermediate heat exchangers 15a, 15b
in FIG. 1, the temperature means may be excluded from the use-side
heat exchanger that does not require the condensation suppression
control.
[0118] Further, although two intermediate heat exchangers 15a, 15b
are provided as shown in FIG. 1, two or more intermediate heat
exchangers may be provided. Since the heat exchange characteristic
can be controlled with respect to each of the intermediate heat
exchangers 15a, 15b as stated above, the heat medium of different
temperatures can be generated for each of the intermediate heat
exchangers. Therefore, while the single intermediate heat exchanger
for adjustment 15b is utilized to perform the condensation
suppression control in Embodiment 1, two or more intermediate heat
exchangers for adjustment may be employed to perform the
condensation suppression control in the case where the intermediate
unit 3 includes three or more intermediate heat exchangers.
REFERENCE SIGNS LIST
[0119] 1: heat source unit, 2, 2a, 2b: use-side unit, 3:
intermediate unit, 4a: first joint pipe, 4b: second joint pipe, 5a:
high-pressure main pipe, 5b: low-pressure main pipe, 9: expansion
device, 10: compressor, 11: first refrigerant flow switching
device, 12: heat source-side heat exchanger, 12a: air-sending
device, 13: flow path provision section, 13a to 13d: check valve,
15, 15a, 15b: intermediate heat exchanger, 16, 16a, 16b: expansion
device, 17a: liquid refrigerant supply valve, 17b: gas refrigerant
supply valve, 18, 18a, 18b: second refrigerant flow switching
device, 19: accumulator, 21, 21a, 21b: pump, 22, 22a, 22b:
secondary-side flow switching device, 23, 23a, 23b: primary-side
flow switching device, 25, 25a, 25b: flow rate control means, 26,
26a, 26b: use-side heat exchanger, 27, 28: heat medium pipe, 31,
31a, 31b: heat medium temperature sensor, 32, 32a, 32b: inlet
temperature sensor, 33, 33a, 33b: inlet humidity sensor, 34, 34a,
34b: outlet water temperature sensor, 35, 35a, 35b: first
refrigerant temperature sensor, 36, 36a, 36b: pressure sensor, 37,
37a, 37b: second refrigerant temperature sensor, 51: heat source
unit control means, 52a, 52b: use-side unit control means, 53:
intermediate unit control means, 53a: maximum dew point detection
means, 53b: heat medium circuit control means, 53c: refrigerant
circuit control means, 53d: calculation processing circuit, 100:
air-conditioning apparatus, 520: target identification means, 521:
target determination means, 522: dew point calculation means, 523:
comparative calculation means, 524: thermostat determination means,
525: operation signal transmission means, 526: control panel, A:
refrigerant circuit, B: heat medium circuit, T: heat medium
temperature, Tr: target set temperature range, Tt: target water
temperature, Tmax: maximum dew point
* * * * *