U.S. patent application number 13/055841 was filed with the patent office on 2011-06-23 for air-conditioning apparatus.
Invention is credited to Takeshi Hatomura, Hiroyuki Morimoto, Yuji Motomura, Koji Yamashita.
Application Number | 20110146339 13/055841 |
Document ID | / |
Family ID | 42128382 |
Filed Date | 2011-06-23 |
United States Patent
Application |
20110146339 |
Kind Code |
A1 |
Yamashita; Koji ; et
al. |
June 23, 2011 |
AIR-CONDITIONING APPARATUS
Abstract
In an air-conditioning apparatus, a heat source side heat
exchanger, intermediate heat exchangers, and use side heat
exchangers are formed in separate bodies respectively and adapted
to be disposed at separate locations one another. In a heat medium
circulation circuit where the intermediate heat exchanger and the
use side heat exchanger are connected, temperature sensors are
installed. An anti-freezing operation mode is provided in which,
when the detection temperatures of the temperature sensors become
equal to or lower than a set temperature Ts while a compressor or
pumps are stopped, the heat medium is circulated to perform
anti-freezing of the heat medium.
Inventors: |
Yamashita; Koji; (Tokyo,
JP) ; Morimoto; Hiroyuki; (Tokyo, JP) ;
Motomura; Yuji; (Tokyo, JP) ; Hatomura; Takeshi;
(Tokyo, JP) |
Family ID: |
42128382 |
Appl. No.: |
13/055841 |
Filed: |
October 29, 2008 |
PCT Filed: |
October 29, 2008 |
PCT NO: |
PCT/JP2008/069606 |
371 Date: |
March 7, 2011 |
Current U.S.
Class: |
62/513 |
Current CPC
Class: |
F24F 11/30 20180101;
F24F 2110/12 20180101; F25B 47/006 20130101; F25B 13/00 20130101;
F25B 2313/0231 20130101; F25B 2313/02741 20130101; F24F 11/41
20180101; F25B 2313/006 20130101; F25D 17/02 20130101; F24F 2140/20
20180101; F24F 2110/10 20180101; F25B 2313/0272 20130101; F24F
11/83 20180101; F25B 2313/0314 20130101; F25B 2313/0233 20130101;
F24F 3/06 20130101; F25B 2313/0232 20130101; F25B 25/005
20130101 |
Class at
Publication: |
62/513 |
International
Class: |
F25B 41/00 20060101
F25B041/00 |
Claims
1. An air-conditioning apparatus, comprising: an intermediate heat
exchanger that exchanges heat between a refrigerant and a different
heat medium from said refrigerant such as water and brine; a
refrigeration cycle that connects a compressor, a heat source side
heat exchanger, at least one expansion valve, and a refrigerant
side flow path of said intermediate heat exchanger via piping
through which said refrigerant flows; and a heat medium circulation
circuit that connects a heat medium side flow path of said
intermediate heat exchanger, a pump, and a use side heat exchanger
via piping through which said heat medium flows, a temperature
sensor that detects a temperature of said heat medium, installed in
said heat medium circulation circuit, wherein said heat source side
heat exchanger, said intermediate heat exchanger, and said use side
heat exchanger are formed in separate bodies respectively, and
there is provided an anti-freezing operation mode in which
anti-freezing operation of said heat medium is performed when a
detection temperature of said temperature sensor becomes equal to
or lower than a set temperature while said compressor or said pump
is stopped, and wherein as said intermediate heat exchanger, an
intermediate heat exchanger that heats said heat medium and an
intermediate heat exchanger that cools said heat medium are
provided, flow path switching valves that switch the flow path to
each intermediate heat exchanger at the inlet side and outlet side
of a heat medium side flow path of said use side heat exchanger are
provided, and in said anti-freezing operation mode for said heat
medium, said flow path switching valves are controlled so that the
heat medium from both the flow path connected with one of said
intermediate heat exchangers and the flow path connected with the
other intermediate heat exchanger is mixed by said flow path
switching valves, and part of the mixed heat medium circulates in
said heat medium circulation circuit corresponding to said
temperature sensor that detected a temperature equal to or lower
than said set temperature.
2. The air-conditioning apparatus of claim 1, wherein in the
anti-freezing operation mode of said heat medium, said temperature
sensor is installed in an inlet side flow path or an outlet side
flow path of said pump, said pump is operated corresponding to said
intermediate heat exchanger corresponding to said temperature
sensor that detected a temperature equal to or lower than said set
temperature, and said heat medium is made to circulate using said
heat medium circulation circuit.
3. The air-conditioning apparatus of claim 1, wherein a bypass is
connected between a heat medium inlet side flow path and a heat
medium outlet side flow path of said use side heat exchanger to
adjust said heat medium flowing through said use side heat
exchanger, and in the anti-freezing operation, said heat medium is
made to circulate through said bypass.
4. The air-conditioning apparatus of claim 1, wherein a
high-temperature high-pressure refrigerant is made to flow into
said intermediate heat exchanger corresponding to said temperature
sensor that detected a temperature equal to or lower than said set
temperature.
5. (canceled)
6. The air-conditioning apparatus of claim 1, wherein in the
anti-freezing operation mode of said heat medium, a flow path
switching valve is provided that switches the flow path according
to a plurality of said intermediate heat exchangers to an inlet
side and an outlet side of the heat medium side flow path of said
use side heat exchanger, respectively, said compressor is operated
and part of a plurality of said intermediate heat exchangers is
operated for heating the heat medium, said flow path switching
valve is switched and the heat medium is circulated from the
intermediate heat exchanger for heating the heat medium to said
intermediate heat exchanger corresponding to said temperature
sensor that detected a temperature equal to or lower than said set
temperature.
7. The air-conditioning apparatus of claim 1, wherein a flow amount
adjustment valve is installed at a heat medium inlet side flow path
or a heat medium outlet side flow path of said use side heat
exchanger, and before or as soon as said pump is operated, said
flow amount adjustment valve is controlled in the direction in
which a circulation flow path of said heat medium is
established.
8. (canceled)
Description
TECHNICAL FIELD
[0001] The present invention relates to an air-conditioning
apparatus such as a multiple air conditioner for buildings.
BACKGROUND ART
[0002] In a multiple air conditioner, which is a conventional
air-conditioning apparatus, cooling energy or heating energy is
delivered indoors by circulating a refrigerant between an outdoor
unit, which is a heat source apparatus installed outdoors, and an
indoor unit installed indoors. As for the refrigerant, an HFC
(hydrofluorocarbon) refrigerant is mainly used and the
air-conditioning apparatus using a natural refrigerant such as CO2
is proposed.
[0003] In a chiller, which is another conventional air-conditioning
apparatus, cooling energy or heating energy is generated in a heat
source apparatus disposed outdoors, cooling energy or heating
energy is transferred to a heat medium such as water and an
anti-freezing liquid at a heat exchanger disposed in an outdoor
unit, and cooling operation or heating operation is performed by
carrying the heat medium to a fan coil unit, a panel heater and the
like, which are of an indoor unit (Refer to Patent Literature 1,
for example). [0004] Patent Literature 1: Japanese Unexamined
Patent Application Publication No. 2003-343936
SUMMARY OF INVENTION
Technical Problem
[0005] In the conventional air-conditioning apparatus, since the
refrigerant such as HFC is transferred into the indoor unit and
utilized, an environment in the room is deteriorated when the
refrigerant leaks indoors disadvantageously. In the case of the
chiller, since heat exchange is performed outdoors between the
refrigerant and water and the water is transferred to the indoor
unit, carrying power of water is extremely large and non-energy
saving, disadvantageously. Further, there was a fear that water in
the piping may possibly freeze.
[0006] The present invention is made to solve the above-mentioned
problems and its object is to obtain an air-conditioning apparatus
having an excellent energy-saving property and an anti-freezing
design of the indoor unit side heat medium without circulating the
refrigerant such as HFC in the indoor unit.
Solution to Problem
[0007] The air-conditioning apparatus according to the present
invention comprises: at least one intermediate heat exchanger that
exchanges heat between a refrigerant and a heat medium that is
different from the refrigerant; a refrigeration cycle in which a
compressor, a heat source side heat exchanger, at least one
expansion valve, and a refrigerant side flow path of the
intermediate heat exchanger are connected via piping through which
the refrigerant flows; and a heat medium circulation circuit in
which a heat medium side flow path of the intermediate heat
exchanger, a pump, and a use side heat exchanger are connected via
piping through which the heat medium flows.
[0008] The heat source side heat exchanger, the intermediate heat
exchanger, and the use side heat exchanger are formed in separate
bodies respectively and adapted to be disposed at separate
locations one another.
[0009] A temperature sensor is installed in the heat medium
circulation circuit and there is provided an anti-freezing
operation mode in which when a detection temperature of the
temperature sensor becomes equal to or lower than a set temperature
while the compressor or the pump is stopped, anti-freezing
operation of the heat medium is performed. In the anti-freezing
operation mode, the pump of the heat medium circulation circuit
corresponding to the temperature sensor that detected a temperature
equal to or lower than a set temperature was made to operate and
the heat medium is made to circulate using the heat medium
circulation circuit, for example.
Advantageous Effects of Invention
[0010] The air-conditioning apparatus according to the present
invention is safe since the problem of refrigerant leakage into the
room like the air-conditioning apparatus such as the multiple air
conditioner for buildings doesn't occur because no HFC refrigerant
is transferred into the indoor unit. The water circulation path is
shorter than the air-conditioning apparatus such as a chiller,
enabling carrying power of the heat medium such as water to be
reduced to achieve energy saving. Further, an anti-freezing
operation mode is provided in which anti-freezing operation of the
heat medium is performed, therefore, the air-conditioning apparatus
having improved reliability can be obtained.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is an entire configuration diagram of an
air-conditioning apparatus according to Embodiment 1 of the present
invention.
[0012] FIG. 2 is another entire configuration diagram of the
air-conditioning apparatus according to Embodiment 1 of the present
invention.
[0013] FIG. 3 is a circuit diagram for a refrigerant and a heat
medium of the air-conditioning apparatus according to Embodiment 1
of the present invention.
[0014] FIG. 4 is a circuit diagram showing the refrigerant and the
heat medium flow at the time of cooling only operation.
[0015] FIG. 5 is a circuit diagram showing the refrigerant and the
heat medium flow at the time of heating only operation.
[0016] FIG. 6 is a circuit diagram showing the refrigerant and the
heat medium flow at the time of cooling-main operation.
[0017] FIG. 7 is a circuit diagram showing the refrigerant and the
heat medium flow at the time of heating-main operation.
[0018] FIG. 8 is a first circuit diagram showing the refrigerant
and the heat medium flow at the time of anti-freezing
operation.
[0019] FIG. 9 is a second circuit diagram showing the refrigerant
and the heat medium flow at the time of anti-freezing
operation.
[0020] FIG. 10 is a third circuit diagram showing the refrigerant
and the heat medium flow at the time of anti-freezing
operation.
[0021] FIG. 11 is a fourth circuit diagram showing the refrigerant
and the heat medium flow at the time of anti-freezing
operation.
[0022] FIG. 12 is a fifth circuit diagram showing the refrigerant
and the heat medium flow at the time of anti-freezing
operation.
[0023] FIG. 13 is a first flow chart showing the operation of
anti-freezing operation mode.
[0024] FIG. 14 is a second flow chart showing the operation of
anti-freezing operation mode.
[0025] FIG. 15 is a third flow chart showing the operation of
anti-freezing operation mode.
[0026] FIG. 16 is a fourth flow chart showing the operation of
anti-freezing operation mode.
[0027] FIG. 17 is a fifth flow chart showing the operation of
anti-freezing operation mode.
REFERENCE SIGNS LIST
[0028] 1 heat source apparatus (outdoor unit) [0029] 2 indoor unit
[0030] 3 relay unit [0031] 3a main relay unit [0032] 3b(1), 3b(2)
sub relay unit [0033] 4 refrigerant pipeline [0034] 5 heat medium
pipeline [0035] 6 outdoor space [0036] 7 indoor space [0037] 8
non-air-conditioning space [0038] 9 building [0039] 10 compressor
[0040] 11 four-way valve [0041] 12 heat source side heat exchanger
[0042] 13a, 13b, 13c, 13d check valve [0043] 14 gas-liquid
separator [0044] 15a, 15b intermediate heat exchanger [0045] 16a,
16b, 16c, 16d, 16e expansion valve [0046] 17 accumulator [0047]
21a, 21b pump [0048] 22a, 22b, 22c, 22d flow path switching valve
[0049] 23a, 23b, 23c, 23d flow path switching valve [0050] 24a,
24b, 24c stop valve [0051] 25a, 25b, 25c, 25d flow amount
adjustment valve [0052] 26a, 26b, 26c, 26d use side heat exchanger
[0053] 27a, 27b, 27c, 27d bypass [0054] 28a, 28b bypass stop valve
[0055] 31a, 31b -first temperature sensor [0056] 32a, 32b second
temperature sensor [0057] 33a, 33b, 33c, 33d third temperature
sensor [0058] 34a, 34b, 34c, 34d fourth temperature sensor [0059]
35 fifth temperature sensor [0060] 36 pressure sensor [0061] 37
sixth temperature sensor [0062] 28 seventh temperature sensor
DESCRIPTION OF EMBODIMENTS
[0063] Detailed descriptions will be given to the embodiment of the
present invention.
Embodiment 1
[0064] FIGS. 1 and 2 are an entire configuration diagram of an
air-conditioning apparatus according to Embodiment 1 of the present
invention. The air-conditioning apparatus includes a heat source
apparatus (outdoor unit) 1, an indoor unit 2 subjected to air
conditioning of indoors, and a relay unit 3 that is separated from
the outdoor unit 1 to be disposed in a non-air-conditioning space 8
or the like. The heat source apparatus 1 and the relay unit 3 are
connected by a refrigerant pipeline 4 in which a refrigerant
subjected to two-phase transition or a refrigerant (a primary
medium) under a supercritical state flows. The relay unit 3 and the
indoor unit 2 are connected by a pipeline 5 in which a heat medium
(a secondary medium) such as water, brine, or anti-freezing liquid
flows. The relay unit 3 exchanges heat between the refrigerant
transferred from the heat source apparatus 1 and the heat medium
transferred from the indoor unit 2.
[0065] The heat source apparatus 1 is usually disposed in an
outdoor space 6, which is an external space of structures such as
building 9. The indoor unit 2 is disposed at a position capable of
carrying heated or cooled air to an indoor space 7 such as a living
room inside of structures such as building 9. The relay unit 3 is
housed in a different housing from the heat source apparatus 1 and
the indoor unit 2, being connected to them by the refrigerant
pipeline 4 and the heat medium pipeline 5 of the heat medium, and
being adapted to be capable of being disposed at a different
location from the outdoor space 6 and the indoor space 7. In FIG.
1, the relay unit 3 is inside the building 9, however, being
disposed in a non-air-conditioning space 8 such as under the roof,
which is a different space from the indoor space 7. The relay unit
3 can be disposed in a common use space having an elevator or the
like.
[0066] The heat source apparatus.1 and the relay unit 3 are
configured so as to be connected using two refrigerant pipelines 4.
The relay unit 3 and each indoor unit 2 are connected using two
heat medium pipelines 5 respectively. Connection using two
pipelines facilitates the construction of the air-conditioning
apparatus.
[0067] FIG. 2 shows a case where a plurality of relay units 3 are
provided. That is, the relay unit 3 is divided into one main relay
unit 3a and two sub relay units 3b (1) and 3b(2) derived therefrom.
Accordingly, a plurality of sub relay units 3b can be connected
with one main relay unit 3a. In this configuration, there are three
connection pipelines between the main relay unit 3a and the sub
relay units 3b.
[0068] In FIGS. 1 and 2, the indoor unit 2 is shown with a ceiling
cassette type being an example, however, it is not limited thereto.
Any type such as a ceiling-concealed type and a ceiling-suspended
type will be allowable as long as heated or cooled air can be blown
out into the indoor space 7 directly or through a duct or the
like.
[0069] The heat source apparatus 1 is explained with the case of
being disposed in the outdoor space 6 outside the building 9 as an
example, however, it is not limited thereto. For example, the heat
source apparatus 1 may be disposed in a surrounded space such as a
machine room with a ventilating opening. The heat source apparatus
1 may be disposed inside the building 9 to discharge exhaust heat
to outside of the building 9 through an exhaust duct.
Alternatively, a water-cooled type heat source apparatus may be
employed to be disposed in the building 9.
[0070] The relay unit 3 may be disposed near the heat source
apparatus 1. However, when the distance from the relay unit 3 to
the indoor unit 2 is too long, since the carrying power of the heat
medium becomes large, the energy-saving effect is made to be
weakened.
[0071] Next, descriptions will be given to detailed configuration
of the above air-conditioning apparatus. FIG. 3 is a circuit
diagram for the refrigerant and the heat medium of the
air-conditioning apparatus according to Embodiment 1 of the present
invention. The air-conditioning apparatus, as shown in FIG. 3, has
a heat source apparatus 1, an indoor unit 2, and a relay unit
3.
[0072] The heat source apparatus 1 includes a compressor 10, a
four-way valve 11, a heat source side heat exchanger 12, check
valves 13a, 13b, 13c and 13d, and an accumulator 17. The indoor
unit 2 includes use side heat exchangers 26a to 26d. The relay unit
3 includes a main relay unit 3a and a sub relay unit 3b. The main
relay unit 3a includes a gas-liquid separator 14 to separate a gas
phase and a liquid phase of the refrigerant and an expansion valve
16e (an electronic expansion valve, for example).
[0073] The sub relay unit 3b includes intermediate heat exchangers
15a and 15b, expansion valves (electronic expansion valves, for
example) 16a to 16d, pumps 21a and 21b, and flow path switching
valves 22a to 22d and 23a to 23d such as a three-way valve. The
flow path switching valves are installed at inlet side flow paths
and outlet side flow paths of each use side heat exchanger 26a to
26d, correspondingly. The flow path switching valves 22a to 22d
switch outlet side flow paths among plurally disposed intermediate
heat exchangers. The flow path switching valves 23a to 23d switch
inlet side flow paths thereof. In this example, the flow path
switching valves 22a to 22d perform the operation to switch outlet
side flow paths between the intermediate heat exchangers 15a and
15b, and the flow path switching valves 23a to 23d perform the
operation to switch inlet side flow paths between the intermediate
heat exchangers 15a and 15b.
[0074] At inlet sides of the use side heat exchangers 26a to 26d,
stop valves 24a to 24d are provided, and at outlet sides of the use
side heat exchangers 26a to 26d, flow amount adjustment valves 25a
to 25d are provided, respectively. The inlet side and the outlet
side of each use side heat exchanger 26a to 26d are connected by
bypasses 27a to 27d via the flow amount: adjustment valves 25a to
25d.
[0075] The sub relay unit 3b further includes temperature sensors
and pressure sensors as follows: [0076] the temperature sensors
(first temperature sensors) 31a and 31b to detect the outlet
temperature of the heat medium of the intermediate heat exchangers
15a and 15b; [0077] the temperature sensors (second temperature
sensors) 32a and 32b to detect the inlet temperature of the heat
medium of the intermediate heat exchangers 15a and 15b; [0078] the
temperature sensors (third temperature sensors) 33a to 33d to
detect the inlet temperature of the heat medium of the use side
heat exchangers 26a to 26d; [0079] the temperature sensors (fourth
temperature sensors) 34a to 34d to detect the outlet temperature of
the heat medium of the use side heat exchangers 26a to 26d; [0080]
the temperature sensor (a fifth temperature sensor) 35 to detect
the refrigerant outlet temperature of the intermediate heat
exchanger 15a; [0081] the pressure sensor 36 to detect the
refrigerant outlet pressure of the intermediate heat exchanger 15a;
[0082] the temperature sensor (a sixth temperature sensor) 37 to
detect the refrigerant inlet temperature of the intermediate heat
exchanger 15b; and [0083] the temperature sensor (a seventh
temperature sensor) 38 to detect the refrigerant outlet temperature
of the intermediate heat exchanger 15b.
[0084] These temperature sensors and pressure sensors can employ a
variety of thermometers, temperature sensors, pressure gauge, and
pressure sensors.
[0085] The compressor 10, the four-way valve 11, the heat source
side heat exchanger 12, the check valves 13a, 13b, 13c and 13d, the
gas-liquid separator 14, the expansion valves 16a to 16e, the
intermediate heat exchangers 15a and 15b, and the accumulator 17
configure a refrigeration cycle.
[0086] The intermediate heat exchanger 15a, the pump 21a, the flow
path switching valves 22a to 22d, the stop valves 24a to 24d, the
use side heat exchangers 26a to 26d, the flow amount adjustment
valves 25a to 25d, and the flow path switching valves 23a to 23d
configure a heat medium circulation circuit. In the same way, the
intermediate heat exchanger 15b, the pump 21b, the flow path
switching valves 22a to 22d, the stop valves 24a to 24d, the use
side heat exchangers 26a to 26d, the flow amount adjustment valves
25a to 25d, and the flow path switching valves 23a to 23d configure
a heat-medium circulation circuit.
[0087] As shown in figures, each of use side heat exchangers 26a to
26d is provided with the intermediate heat exchangers 15a and 15b
in parallel in plural, each configuring the heat medium circulation
circuit.
[0088] In the heat source apparatus 1, a controller 100 is provided
that controls equipment constituting thereof to make the heat
source apparatus 1 perform operations as, what is called, an
outdoor unit. In the relay unit 3, a controller 300 is provided
that controls equipment constituting thereof and has means to
perform operations to be mentioned later. These controllers 100 and
300 are composed of such as microcomputers to be communicably
connected with each other. Next, operations of each operation mode
of the above air-conditioning apparatus will be explained.
[0089] <Cooling Only Operation>
[0090] FIG. 4 is a circuit diagram showing a refrigerant and a heat
medium flow at the time of cooling only operation. In the cooling
only operation, the refrigerant is compressed by the compressor 10,
turned into a high-temperature high-pressure gas refrigerant to
enter the heat source side heat exchanger 12 via the four-way valve
11. The refrigerant is condensed and liquefied there, passes
through the check valve 13a, and flowed out of the heat source
apparatus 1 to flow into the relay unit 3 via the refrigerant
pipeline 4. In the relay unit 3, the refrigerant enters the
gas-liquid separator 14 to be guided into the intermediate heat
exchanger 15b via the expansion valves 16e and 16a. Thereby, the
refrigerant is expanded by the expansion valve 16a to turn into a
low-temperature low-pressure two-phase refrigerant and the
intermediate heat exchanger 15b operates as an evaporator. The
refrigerant turns into a low-temperature low-pressure gas
refrigerant in the intermediate heat exchanger 15b and flows out of
the relay unit 3 via the expansion valve 16c to flow into the heat
source apparatus 1 again via the refrigerant pipeline 4. In the
heat source apparatus 1, the refrigerant passes through the check
valve 13d to be sucked into the compressor 10 via the four-way
valve 11 and the accumulator 17. Then, the expansion valves 16b and
16d have an opening-degree small enough for the refrigerant not to
flow and the expansion valve 16c is made to be a full-open state so
as not to cause a pressure loss.
[0091] Next, descriptions will be given to movement of the
secondary side heat medium (water, anti-freezing liquid, etc.) In
the intermediate heat exchanger 15b, cooling energy of the
refrigerant on the primary side is transferred to the heat medium
on the secondary side, and cooled heat medium is made to flow in
the secondary side piping by the pump 21b. The heat medium flowed
out of the pump 21b passes through the stop valves 24a to 24d via
the flow path switching valves 22a to 22d to flow into the use side
heat exchangers 26a to 26d and the flow amount adjustment valves
25a to 25d. Then, through the operation of the flow amount
adjustment valves 25a to 25d, only the heat medium having a flow
amount necessary to cover the air-conditioning load required
indoors is made to flow into the use side heat exchangers 26a to
26d, and the remaining passes through the bypasses 27a to 27d to
make no contribution to heat exchange. The heat medium passing
through the bypasses 27a to 27d merges with the heat medium passing
through the use side heat exchangers 26a to 26d, passes through the
flow path switching valves 23a to 23d, and flows into the
intermediate heat exchanger 15b to be sucked again into the pump
21b.
[0092] The air-conditioning load required indoors can be covered by
controlling the flow amount of the heat medium passing through the
use side heat exchangers 26a to 26d so that a difference between
the detection temperatures of the third temperature sensors 33a to
33d and the fourth temperature sensors 34a to 34d is maintained at
a predetermined target value by the controller 300. It will be the
same in the case of heating only operation, cooling-main operation,
and heating-main operation.
[0093] Since there is no need to flow the heat medium to the use
side heat exchanger (including thermo-off) having no
air-conditioning load, the flow path is closed by the stop valves
24a to 24d and the heat medium is made not to flow into the use
side heat exchanger. In FIG. 9, while in the use side heat
exchangers 26a and 26b, the heat medium is made to flow because of
a air-conditioning load, in the use side heat exchangers 26c and
26d, there is no air-conditioning load and corresponding stop
valves 24c and 24d are closed.
[0094] <Heating Only Operation>
[0095] FIG. 5 is a circuit diagram showing a refrigerant and a heat
medium flows at the time of heating only operation. In the heating
only operation, the refrigerant is compressed by the compressor 10,
turns into a high-temperature high-pressure gas refrigerant, passes
through the check valve 13b via the four-way valve 11, and flows
out of the heat source apparatus 1 via the check valve 13b to flow
into the relay unit 3 via the refrigerant pipeline 4. In the relay
unit 3, the refrigerant is guided into the intermediate heat
exchanger 15a through the gas-liquid separator 14, condensed and
liquefied in the intermediate heat exchanger 15a to flow out of the
relay unit 3 through the expansion valves 16d and 16b. Thereby, the
refrigerant is expanded by the expansion valve 16b, turned into a
low-temperature low-pressure two-phase refrigerant, and flows into
the heat source apparatus 1 again through the refrigerant pipeline
4. In the heat source apparatus 1, the refrigerant is guided into
the heat source side heat exchanger 12 through the check valve 13c
and the heat source side heat exchanger 12 operates as an
evaporator. The refrigerant turns into a low-temperature
low-pressure gas refrigerant there to be sucked into the compressor
10 via the four-way valve 11 and the accumulator 17. Thereby, the
expansion valve 16e and the expansion valve 16a or 16c are made to
have a small opening-degree so that no refrigerant flows
therethrough.
[0096] Next, movement of the secondary side heat medium (water,
anti-freezing liquid, etc.) will be explained. In the intermediate
heat exchanger 15a, heating energy of the primary side refrigerant
is transferred to the secondary side heat medium and the heated
heat medium is made to flow in the secondary side piping by the
pump 21a. The heat medium flowed out of the pump 21a passes through
the stop valves 24a to 24d via the flow path switching valves 22a
to 22d to flow into the use side heat exchangers 26a to 26d and the
flow amount adjustment valves 25a to 25d. Then, through the
operation of the flow amount adjustment valves 25a to 25d, only the
heat medium having a flow amount necessary to cover the
air-conditioning load required indoors is made to flow into the use
side heat exchangers 26a to 26d, and the remaining passes through
the bypasses 27a to 27d to make no contribution to heat exchange.
The heat medium passing through the bypasses 27a to 27d merges with
the heat medium passing through the use side heat exchangers 26a to
26d, passes through the flow path switching valves 23a to 23d, and
flows into the intermediate heat exchanger 15a to be sucked again
into the pump 21a. The air-conditioning load required indoors can
be covered by controlling a difference between the detection
temperatures of the third temperature sensors 33a to 33d and the
fourth temperature sensors 34a to 34d to maintain a target value in
advance.
[0097] Since there is no need to flow the heat medium to the use
side heat exchanger (including thermo-off) having no
air-conditioning load, the flow path is closed by the stop valves
24a to 24d and the heat medium is made not to flow into the use
side heat exchanger. In FIG. 5, while in the use side heat
exchangers 26a and 26b, the heat medium is made to flow because of
a air-conditioning load, in the use side heat exchangers 26c and
26d there is no air-conditioning load and corresponding stop valves
24c and 24d are closed.
[0098] <Cooling-Main Operation>
[0099] FIG. 6 is a circuit diagram showing a refrigerant and a heat
medium flow at the time of cooling-main operation. In the
cooling-main operation, the refrigerant is compressed by the
compressor 10, turned into a high-temperature high-pressure gas
refrigerant to be guided into the heat source side heat exchanger
12 via the four-way valve 11. There, the gas-state refrigerant is
condensed to turn into a two-phase refrigerant, flows out of the
heat source side heat exchanger 12 in the two-phase state, flows
out of the heat source apparatus 1 via the check valve 13a, and
flows into the relay unit 3 via the refrigerant pipeline 4. In the
relay unit 3, the refrigerant enters the gas-liquid separator 14
and a gas refrigerant and a liquid refrigerant in the two-phase
refrigerant are separated. The gas refrigerant is guided into the
intermediate heat exchanger 15a, condensed and liquefied therein to
pass through the expansion valve 16d. Meanwhile, the liquid
refrigerant separated in the gas-liquid separator 14 is flowed to
the expansion valve 16e, joined with the liquid refrigerant
condensed and liquefied in the intermediate heat exchanger 15a and
passing through the expansion valve 16d, and guided to the
intermediate heat exchanger 15b via the expansion valve 16a. Then,
the refrigerant is expanded by the expansion valve 16a to turn into
a low-temperature low-pressure two-phase refrigerant and the
intermediate heat exchanger 15b operates as an evaporator. The
refrigerant turns into a low-temperature low-pressure gas
refrigerant in the intermediate heat exchanger 15b and flows out of
the relay unit 3 via the expansion valve 16c to flow into the heat
source apparatus 1 again via the refrigerant pipeline 4. In the
heat source apparatus 1, the refrigerant passes through the check
valve 13d to be sucked into the compressor 10 via the four-way
valve 11 and the accumulator 17. Then, the expansion valves 16b has
an opening-degree small enough for the refrigerant not to flow and
the expansion valve 16c is made to be a full open state so as not
to cause a pressure loss.
[0100] Next, descriptions will be given to movement of the
secondary side heat medium (water, anti-freezing liquid, etc.) In
the intermediate heat exchanger 15a, heating energy of the
refrigerant on the primary side is transferred to the heat medium
on the secondary side, and heated heat medium is made to flow in
the secondary side piping by the pump 21a. In the intermediate heat
exchanger 15b, cooling energy of the refrigerant on the primary
side is transferred to the heat medium on the secondary side, and
cooled heat medium is made to flow in the secondary side piping by
the pump 21b. The heat medium flowed out of the pumps 21a and 21b
passes through the stop valves 24a to 24d via the flow path
switching valves 22a to 22d to flow into the use side heat
exchangers 26a to 26d and the flow amount adjustment valves 25a to
25d. Then, through the operation of the flow amount adjustment
valves 25a to 25d, only the heat medium having a flow amount
necessary to cover the air-conditioning load required indoors is
made to flow into the use side heat exchangers 26a to 26d, and the
remaining passes through the bypasses 27a to 27d to make no
contribution to heat exchange. The heat medium passing through the
bypasses 27a to 27d merges with the heat medium passing through the
use side heat exchangers 26a to 26d, and passes through the flow
path switching valves 23a to 23d. The heated heat medium flows into
the intermediate heat exchanger 15a to return to the pump 21a
again, and the cooled heat medium flows into the intermediate heat
exchanger 15b to return to the pump 21b again, respectively.
Meanwhile, the heated heat medium and the cooled heat medium are
guided to the use side heat exchangers 26a to 26d having the
heating load and the cooling load, respectively, without being
mixed through the operation of the flow path switching valves 22a
to 22d and 23a to 23d. The air-conditioning load required indoors
can be covered by controlling a difference between the detection
temperatures of the third temperature sensors 33a to 33d and the
fourth temperature sensors 34a to 34d to maintain a target
value.
[0101] FIG. 6 shows a state in which a heating load is generated in
the use side heat exchanger 26a and a cooling load is generated in
the use side heat exchanger 26b, respectively.
[0102] Since there is no need to flow the heat medium to the use
side heat exchanger (including thermo-off) having no
air-conditioning load, the flow path is closed by the stop valves
24a to 24d and the heat medium is made not to flow into the use
side heat exchanger. In FIG. 6, while in the use side heat
exchangers 26a and 26b, the heat medium is made to flow because of
a air-conditioning load, in the use side heat exchangers 26c and
26d, there is no air-conditioning load and corresponding stop
valves 24c and 24d are closed.
[0103] <Heating-Main Operation>
[0104] FIG. 7 is a circuit diagram showing a refrigerant and heat
medium flow at the time of heating-main operation. In the
heating-main operation, the refrigerant is compressed by the
compressor 10, turns into a high-temperature high-pressure gas
refrigerant, passes through the check valve 13b via the four-way
valve 11, and flows out of the heat source apparatus 1 to flow into
the relay unit 3 via the refrigerant pipeline 4. In the relay unit
3, the refrigerant is introduced into the intermediate heat
exchanger 15a through the gas-liquid separator 14, and condensed
and liquefied in the intermediate heat exchanger 15a. Thereafter,
the refrigerant passing through the expansion valve 16d is branched
into flow paths through the expansion valves 16a and 16b. The
refrigerant passing through the expansion valve 16a is expanded by
the expansion valve 16a to turn into a low-temperature low-pressure
two-phase refrigerant and flows into the intermediate heat
exchanger 15b. The intermediate heat exchanger 15b operates as an
evaporator. The refrigerant flowed out of the intermediate heat
exchanger 15b evaporates to turn into a gas refrigerant and passes
through the expansion valve 16c. On the other hand, the refrigerant
passing through the expansion valve 16b is expanded by the
expansion valve 16b to turn into a low-temperature low-pressure
two-phase refrigerant, and merges with the refrigerant passing
through the intermediate heat exchanger 15b and the expansion valve
16c to turn into a low-temperature low-pressure refrigerant having
larger dryness. Then, the merged refrigerant flows out of the relay
unit 3 to flow into the heat source apparatus 1 again through the
refrigerant pipeline 4. In the heat source apparatus 1, the
refrigerant passes through the check valve 13c to be guided into
the heat source side heat exchanger 12. The heat source side heat
exchanger 12 operates as an evaporator. Then, the low-temperature
low-pressure two-phase refrigerant is evaporated into a gas
refrigerant and sucked into the compressor 10 via the four-way
valve 11 and the accumulator 17. Then, the expansion valve 16e is
made to have a small opening-degree so that no refrigerant
flows.
[0105] Next, movement of the secondary side heat medium (water,
anti-freezing liquid, etc.) will be explained. In the intermediate
heat exchanger 15a, heating energy of the primary side refrigerant
is transferred to the secondary side heat medium and the heated
heat medium is made to flow in the secondary side piping by the
pump 21a. In the intermediate heat exchanger 15b, cooling energy of
the primary side refrigerant is transferred to the secondary side
heat medium and the cooled heat medium is made to flow in the
secondary side piping by the pump 21b. Then, the heat medium flowed
out of the pumps 21a and 21b passes through the stop valves 24a to
24d via the flow path switching valves 22a to 22d to flow into the
use side heat exchangers 26a to 26d and flow amount adjustment
valves 25a to 25d. Then, through the operation of the flow amount
adjustment valves 25a to 25d, only the heat medium having a flow
amount necessary to cover the air-conditioning load required
indoors is made to flow into the use side heat exchangers 26a to
26d, and the remaining passes through the bypasses 27a to 27d to
make no contribution to heat exchange. The heat medium passing
through the bypasses 27a to 27d merges with the heat medium passing
through the use side heat exchangers 26a to 26d, passes through the
flow path switching valves 23a to 23d. The heated heat medium flows
into the intermediate heat exchanger 15a to return to the pump 21a
again, and the cooled heat medium flows into the intermediate heat
exchanger 15b to return to the pump 21b again. Meanwhile, the
heated heat medium and the cooled heating medium are guided to the
use side heat exchangers 26a to 26d having the heating load and the
cooling load, respectively, without being mixed through the
operation of the flow path switching valves 22a to 22d and 23a to
23d. The air-conditioning load required indoors can be covered by
controlling a difference between the detection temperatures of the
third temperature sensors 33a to 33d and the fourth temperature
sensors 34a to 34d to maintain a target value.
[0106] FIG. 7 shows a state in which a heating load is generated in
the use side heat exchanger 26a and a cooling load is generated in
the use side heat exchanger 26b, respectively.
[0107] Since there is no need to flow the heat medium to the use
side heat exchanger (including thermo-off) having no
air-conditioning load, the flow path is closed by the stop valves
24a to 24d and the heat medium is made not to flow into the use
side heat exchanger. In FIG. 7, while in the use side heat
exchangers 26a and 26b, the heat medium is made to flow because of
a air-conditioning load, in the use side heat exchangers 26c and
26d, there is no air-conditioning load and corresponding stop
valves 24c and 24d are closed.
[0108] As mentioned above, heating operation and cooling operation
can be freely performed in each indoor unit 2 by switching the
corresponding flow path switching valves 22a to 22d and 23a to 23d
to the flow path connected to the heating intermediate heat
exchanger 15a when heating load is generated in the use side heat
exchangers 26a to 26d, and by switching the corresponding flow path
switching valves 22a to 22d and 23a to 23d to the flow path
connected to the cooling intermediate heat exchanger 15b when
cooling load is generated in the use side heat exchangers 26a to
26d.
[0109] The flow path switching valves 22a to 22d and 23a to 23d may
be any that can switch flow paths such as a combination of a
three-way valve to switch three-way flow paths arid a stop valve to
open/close two-way flow paths. The flow path switching valve may be
configured by a combination of a stepping-motor-driven mixing valve
to change the flow amount of three-way flow paths and an electronic
expansion valve to change the flow amount of two-way flow paths. In
that case, water hammer can be prevented by a sudden
opening/closing of the flow path.
[0110] The air-conditioning load in the use side heat exchangers
26a to 26d is expressed by formula 1, being obtained by multiplying
the flow rate, the density, the constant pressure specific heat of
the heat medium and the difference in temperature of the heat
medium at the inlet and at the outlet of the use side heat
exchangers 26a to 26d. Here, Vw denotes the flow amount of the heat
medium, .rho.w the density of the heat medium, Cpw the constant
pressure specific heat of the heat medium, Tw the temperature of
the heat medium, suffix "in" the value at the inlet of the heat
medium of the use side heat exchangers 26a to 26d, suffix "out" the
value at the outlet of the heat medium of the use side heat
exchangers 26a to 26d, respectively.
Formula 1
Q=V.sub.w*(.rho..sub.win*Cp.sub.win*T.sub.win-.rho..sub.wout*Cp.sub.wout-
*T.sub.wout).about.V.sub.w*.rho..sub.w*Cp.sub.w*(T.sub.win-T.sub.wout.
(1)
[0111] When the flow amount of the heat medium flowing to the use
side heat exchangers 26a to 26d is fixed, the temperature
difference of the heat medium at the inlet and the outlet changes
according to the change of the air-conditioning load in the use
side heat exchangers 26a to 26d. Therefore, the temperature
difference at the inlet and outlet of the use side heat exchanger
26a to 26d is set to be a temporary target and it is possible to
flow surplus heat medium to the bypasses 27a to 27d to control the
flow amount that follows to the use side heat exchangers 26a to 26d
by controlling the flow amount adjustment valves 25a to 25d so that
the temporary target approaches a predetermined target value. The
target value of the temperature difference at the inlet and outlet
of the use side heat exchangers 26a to 26d may be set at, for
example, 5 degrees C.
[0112] In FIGS. 3 to 7, descriptions are given to the case where
the flow amount adjustment valves 25a to 25d are a mixing valve
installed at the downstream side of the use side heat exchangers
26a to 26d, however, a three-way valve is allowable installed at
the upstream side of the use side heat exchangers 26a to 26d.
[0113] Then, the heat medium that exchanged heat with the use side
heat exchangers 26a to 26d and heat medium that passed through the
bypasses 27a to 27d with no-heat exchange and no change in
temperature merge at a merged section thereafter. Formula (2) holds
in the merged section. Here, Twin and Twout denote the heat medium
temperatures at the inlet and the outlet of the use side heat
exchangers 26a to 26d, Vw the flow amount of the heat medium
flowing into the flow amount adjustment valves 25a to 25d, Vwr the
flow amount of the heat medium flowing into the use side heat
exchangers 26a to 26d, Tw the temperature of heat medium after the
heat medium flowing through the use side heat exchangers 26a to 26d
and the heat medium flowing through the bypasses 27a to 27d are
merged.
Formula 2
T.sub.w=(V.sub.wr/V.sub.w)*T.sub.wout+(1-V.sub.wr/V.sub.w)*T.sub.win
(2)
[0114] When the heat medium that exchanged heat in the use side
heat exchangers 26a to 26d to have a change in temperature and the
heat medium that passed through the bypasses 27a to 27d with no
heat exchange and no change in temperature merge, the temperature
difference between the heat media approaches the inlet temperature
of the use side heat exchangers 26a to 26d by the flow amount that
is bypassed. For example, when the total flow amount is 20 L/min,
the inlet temperature of the heat medium of the use side heat
exchangers 26a to 26d 7 degrees C., the outlet temperature 13
degrees C., the flow amount flowed toward the use side heat
exchangers 26a to 26d side 10 L/min, the temperature after merging
becomes 10 degrees C. by formula (2).
[0115] The heat medium having the temperature after the merging
returns from each indoor unit to merge and flows into the
intermediate heat exchangers 15a and 15b. Then, unless the heat
exchange amount of the intermediate heat exchanger 15a or 15b
changes, the temperature difference between the inlet and outlet
becomes almost the same through the heat exchange in the
intermediate heat exchanger 15a or 15b. For example, it is assumed
that the temperature difference between the inlet and outlet of the
intermediate heat exchanger 15a or 15b is 6 degrees C., and at
first, the inlet temperature of the intermediate heat exchanger 15a
or 15b is 13 degrees C. and the outlet temperature is 7 degrees C.
Further, the air-conditioning load in the use side heat exchangers
26a to 26d is lowered and the inlet temperature of the intermediate
heat exchanger 15a or 15b decreases to 10 degrees C. Then, if
nothing be done, since the intermediate heat exchanger 15a or 15b
performs heat exchange of almost the same amount, the heat medium
flows out of the intermediate heat exchanger 15a or 15b at 4
degrees C. The above is repeated and the temperature of the heat
medium rapidly decreases.
[0116] In order to prevent the above, the rotation speed of the
pumps 21a and 21b may be changed according to changes in the
air-conditioning load of the use side heat exchangers 26a to 26d so
that the heat medium outlet temperature of the intermediate heat
exchanger 15a or 15b approaches a target value. Thereby, when the
air-conditioning load is lowered, the rotation speed of the pump
decreases to achieve energy-saving. When the air-conditioning load
increases, the rotation speed of the pump increases to cover the
air-conditioning load.
[0117] The pump 21b operates when cooling load or dehumidifying
load occurs in any of the use side heat exchangers 26a to 26d, and
is stopped when there is neither cooling load nor dehumidifying
load in each use side heat exchangers 26a to 26d. The pump 21a
operates when the heating load occurs in any of the use side heat
exchangers 26a to 26d, and is stopped when there is no heating load
in any of use side heat exchangers 26a to 26d.
[0118] Next descriptions will be given to anti-freezing of the heat
medium flow path. The heat medium flow path at `the secondary side
from the intermediate heat exchangers 15a and 15b to the use side
heat exchangers 26a to 26d is in general disposed inside of the
building and is usually maintained at a hi.sub.gher temperature
than a freezing temperature of the heat medium, 0 degree C. in the
case of water, for example. However, in the case which the
compressor 10 and the pump 21a or 21b are stopped for a long time,
or the intermediate heat exchangers 15a and 15b are disposed
outdoors, the heat medium flow path may he cooled to reach the
refrigeration temperature. Accordingly, an anti-freezing operation
is required that prevents the heat medium from freezing.
Descriptions will be given to the heat medium anti-freezing
operation (anti-freezing operation mode).
[0119] The anti-freezing operation is performed through the
operation of heat medium anti-freezing operation means of the
controller 300. The controller 300 performs the anti-freezing
operation when the detection temperature of any of the first
temperature sensors 31a and 31b, the second temperature sensors 32a
and 32b, the third temperature sensors 33a to 33b, and the fourth
temperature sensors 34a to 34d becomes equal to or lower than a
predetermined set temperature.
[0120] When any of the above-mentioned detection temperatures
becomes equal to or lower than the set temperature, the temperature
of the whole heat medium flow path can be made uniform by making
the pump 21a or 21b to operate to circulate the heat medium and
agitating the heat medium in the heat medium piping to rise the
temperature of the heat medium at the part where the temperature
has decreased and prevent freezing.
[0121] It depends on which of the above-mentioned detection
temperature detection means has detected equal to or lower than the
set temperature to operate either the pump 21a or 21b. That is,
when either the first temperature sensor 31a or the second
temperature sensor 32a detects equal to or lower than the set
temperature, the pump 21a is made to operate. When either the first
temperature sensor 31b or the second temperature sensor 32b detects
equal to or lower than the set temperature, the pump 21b is made to
operate. Further, when either the third temperature sensors 33a to
33d or the fourth temperature sensors 34a to 34d detects equal to
or lower than the set temperature, either the pump 21a or 21b that
is connected with the corresponding use side heat exchangers 26a to
26d is made to operate to circulate the heat medium.
[0122] The operation of the above-mentioned anti-freezing operation
by the controller 300 will be explained by the flow chart of FIG.
13. In the explanation of each flow chart, the flow path switching
valves 22a to 22d are explained as the flow path switching valve
22, the flow path switching valves 23a to 23d as the flow path
switching valve 23, the stop valves 24a to 24d as the stop valve
24, the flow amount adjustment valves 25a to 25d as the flow amount
adjustment valve 25, the bypasses 27a to 27d as the bypass 27, the
third temperature sensors 33a to 33d as the third temperature
sensor 33,and the fourth temperature sensors 34a to 34d as the
fourth temperature sensor 34.
[0123] After the processing starts (STO), the controller 300
operates the pump 21a (ST5) when the first temperature sensor 31a
or the second temperature sensor 32a detects the temperature equal
to or lower than the set temperature Ts (ST1, ST2). The controller
300 operates the pump 21b (ST6) when the first temperature sensor
31b or the second temperature sensor 32b detects the temperature
equal to or lower than the set temperature Ts (ST3, ST4). When any
of these are detected, the flow path switching valve 22
corresponding to the use side heat exchanger 26a of the first
indoor unit (1) is switched to the heating intermediate heat
exchanger 15a, the flow path switching valve 23 to the cooling
intermediate heat exchanger 15b, for example. Further, the flow
path switching valve 22 corresponding to the use side heat
exchanger 26b of the second indoor unit (2) is switched to the
cooling intermediate heat exchanger 15b, the flow path switching
valve 23 to the heating intermediate heat exchanger 15a, for
example (ST7). The stop valve 24 of the use side heat exchangers
26a and 26b is made to be open and the flow amount adjustment valve
25 is made to be full open to the bypass 27 side.
[0124] From "1" of the indoor unit to the maximum number of
installed units, the detection temperatures of the third
temperature sensor 33 and the fourth temperature sensor 34
corresponding to each unit are searched in order (ST9, ST15, ST16).
When the third temperature sensor 33 or the fourth temperature
sensor 34 detects the temperature equal to or lower than the set
temperature Ts (ST10, ST11), the pump 21a or 21b is made to operate
(ST12). Then, the flow path switching valve 22 of the n-th indoor
unit (n) that detected the temperature equal to or lower than the
set temperature is switched to the heating intermediate heat
exchanger 15a, and the flow path switching valve 23 to the cooling
intermediate heat exchanger 15b. The flow path switching valve 22
of the (n+1)-th indoor unit (n+1) is switched to the cooling
intermediate heat exchanger 15b, and the flow path switching valve
23 to the heating intermediate heat exchanger 15a (ST13). The stop
valve 24 of the indoor units (n) and (n+1) is made to be open and
the flow amount adjustment valve 25 of the indoor unit (n) is made
to be full open at the use side heat exchanger 26 side (ST14).
[0125] When the detection temperatures of all the above-mentioned
temperature sensors become higher than the set temperature Ts
(ST17), the pumps 21a and 21b are made to stop (ST18) to complete
processing (ST19). In cases of ST5, ST6, and ST12, both pumps 21a
and 21b may be operated.
[0126] The above-mentioned heat medium anti-freezing operation mode
is a method of performing anti-freezing by making the heat medium
to circulate with use of the pumps 21a and 21b and agitating the
heat medium in the flow path to make the temperature uniform.
However, with this method, since no heat medium is heated, the heat
medium gets refrigerated eventually when the heat medium flow path
continues to be cooled.
[0127] Therefore, to further perform anti-freezing with accuracy,
when any of the above-mentioned each temperature sensor detect the
temperature equal to or lower than the set temperature, in the
state of operating the pump 21a or 21b corresponding with the
intermediate heat exchanger 15a or 15b corresponding to the
temperature sensor that detects the temperature equal to or lower
than the set temperature, the compressor 10 is made to operate, the
four-way valve 11 is switched to the heating side, the
high-temperature high-pressure refrigerant is introduced into the
intermediate heat exchanger 15a or 15b corresponding to the
temperature sensor that detected the temperature equal to or lower
than the set temperature, and anti-freezing is performed by heating
the heat medium to rise the temperature.
[0128] Operations of the refrigeration cycle then will be
explained. When detecting the temperature equal to or lower than
the set temperature in the flow path corresponding to the
intermediate heat exchanger 15a, normal operation is allowable.
However, when detecting the temperature equal to or lower than the
set temperature in the flow path corresponding to the intermediate
heat exchanger 15b, it is necessary to guide the high-temperature
high-pressure refrigerant into the intermediate heat exchanger 15b.
Therefore, as shown in FIG. 8, by making the expansion valves 16d
and 16a full open and throttling the expansion valve 16c to expand
the refrigerant, it is possible to flow a high-temperature
high-pressure gas refrigerant, a two-phase refrigerant or a liquid
refrigerant into the refrigerant flow path of the intermediate heat
exchanger 15b. Thus, it is possible to prevent freezing by heating
the heat medium that flows through the heat medium flow path of the
intermediate heat exchanger 15b and circulating the heated heat
medium.
[0129] When any of the third temperature sensors 33a to 33d or the
fourth temperature sensors 34a to 34d detect the temperature equal
to or lower than the set temperature, either the pump 21a or 21b is
operated and the heat medium is circulated in the intermediate heat
exchanger 15a or 15b corresponding thereto. Further, the compressor
10 is made to operate, the four-way valve is switched to the
heating side, a high-temperature high-pressure refrigerant is
guided into the intermediate heat exchanger 15a or 15b where the
heat medium circulates, the heat medium is heated to increase
temperature, and the heated heat medium having a increased
temperature is made to circulate in the use side heat exchangers
26a to 26d corresponding to the temperature sensor that detected
the temperature equal to or lower than the set temperature by
switching the flow path switching valves 22a to 22d and 23a to 23d
to perform anti-freezing operation.
[0130] The intermediate heat exchanger is divided into a heating
intermediate heat exchanger 15a and a cooling intermediate heat
exchanger 15b. When either a first temperature sensor 31b or a
second temperature sensor 32b detects a temperature equal to or
lower than the set temperature, a high-temperature high-pressure
refrigerant cannot directly be guided into the cooling intermediate
heat exchanger 15b.
[0131] Then, as shown in FIG. 9, the refrigeration cycle is
operated such that a high-temperature high-pressure refrigerant is
made to circulate in the heating intermediate heat exchanger 15a.
The flow path switching valves 22a to 22d corresponding to the use
side heat exchanger (here, 26a) as a part of the use side heat
exchangers 26a to 26d are switched so as to be connected with the
intermediate heat exchanger 15a, and the flow path switching valves
23a to 23d are switched so as to be connected with the intermediate
heat exchanger 15b. The flow path switching valves 22a to 22d
corresponding to another use side heat exchanger (here, 26b) are
switched so as to be connected with the intermediate heat exchanger
15b, and flow path switching valves 23a to 23d are switched so as
to be connected with the intermediate heat exchanger 15a. Then, the
pumps 21a and 21b are operated and the heat medium heated by the
intermediate heat exchanger 15a is made to circulate in the cooling
intermediate heat exchanger 15b. In FIG. 9, the flow path switching
valve 22a is switched to the outlet side of the heating
intermediate heat exchanger 15a, the flow path switching valve 23a
to the inlet side of the cooling intermediate heat exchanger 15b,
the flow path switching valve 22b to the outlet side of the cooling
intermediate heat exchanger 15b, the flow path switching valve 23b
to the inlet side of the heating intermediate heat exchanger 15a,
and the heat medium is made to circulate between the intermediate
heat exchangers 15a and 15b.
[0132] FIG. 14 is a flow chart illustrating an operation of the
above. Since from RT0 to RT17 in FIG. 14 are the same as from ST0
to ST 17 in FIG. 13 and regarding the circulation of the heat
medium, it is the same as what is explained in the above,
descriptions is omitted. In FIG. 14, the compressor 10 is made to
operate, the four-way valve 11 is switched to the heating side, a
step (RT20) is added to guide a high-temperature high-pressure
refrigerant to the heating intermediate heat exchanger 15a. While
heating the heating intermediate heat exchanger 15a by the
refrigerant, the heat medium heated by the refrigerant is made to
circulate. Then the temperature of the heat medium is increased and
freezing can be prevented. When all detection temperatures of the
temperature detection means become higher than the set temperature
Ts (RT17), the pumps 21a and 21b and the compressor 10 are stopped.
(RT18)
[0133] As shown in FIG. 10, as the flow path switching valves 22a
to 22d and 23a to 23d, a valve is used having a structure allowing
to set at an opening-degree in the midway between full open and
full close such as a stepping motor type. The refrigeration cycle
is operated so that a high-temperature high-pressure refrigerant is
circulated in the heating intermediate heat exchanger 15a. The
pumps 21a and 21b are operated. The heat medium flow path switching
valves 22a and 22d corresponding to part of the use side heat
exchangers 26a to 26d are set at a midway opening-degree that both
of two paths, the heat medium flow path for heating and the heat
medium flow path for cooling, are neither full open nor completely
closed. The heat medium heated by the intermediate heat exchanger
15a and the heat medium passing through the cooling intermediate
heat exchanger 15b are mixed. The heat medium flow path switching
valves 23a to 23d are set at a midway opening-degree that the flow
path is neither full open nor completely closed, as well. The heat
medium mixed in the flow path switching valves 22a to 22d is
adapted to be distributed into the intermediate heat exchanger 15a
and the intermediate heat exchanger 15b. Thus, the heat medium
flowing into the intermediate heat exchanger 15b gets to be a
higher temperature than the heat medium prior to mixing by the heat
amount of the heat medium heated by the intermediate heat exchanger
15a, therefore, freezing of the heat medium can be prevented in the
intermediate heat exchanger 15b.
[0134] The control of the above-mentioned configuration is shown at
a flow chart in FIG. 15. Here, as the heat medium flow path
switching valves 22 and 23, those that can set at an intermediate
opening-degree between full open and full close by a stepping motor
or the like will be used.
[0135] After the processing starts (GT0), when the detection
temperature of the first temperature sensor 31a or the second
temperature sensor 32a corresponding to the intermediate heat
exchanger 15a or the detection temperature of the first temperature
sensor 31b or the second temperature sensor 32b corresponding to
the intermediate heat exchanger 15b is detected to be equal to or
lower than the set temperature Ts (GT1 to GT4), the controller 300
operates the pumps 21a and 21b (GT5). Then, the flow path switching
valves 22 and 23 of a first indoor unit 1 arc set at an
intermediate opening (GT6), for example, and the stop valve 24 of
the first indoor unit 1 is made to be open and the flow amount
adjustment valve 25 is made to be full open at the bypass 27 side
(GT7).
[0136] From "1" of the indoor unit to the maximum number of
installed units, the detection temperatures of the third
temperature sensor 33 and the fourth temperature sensor 34
corresponding to each unit are searched in order (ST9, ST15, ST16).
When those temperature detection means detect the temperature equal
to or lower than the set temperature Ts (ST9, ST10), the pumps 21a
and 21b are made to operate (ST11). The flow path switching valves
22 and 23 of the indoor unit (n) that detected the temperature
equal to or lower than the set temperature Ts is set at an
intermediate opening-degree (GT12), the stop valve 24 of the indoor
unit (n) is made to be open, and the flow amount adjustment valve
25 is made to be full open to the use side heat exchanger 26 side
(GT13).
[0137] When the detection temperature of all the above-mentioned
temperature sensors becomes higher than the set temperature Ts
(ST16), the pumps 21a and 21b are made to stop (ST17) to complete
the processing (ST10). Only either pump 21a or 21b may be operated
in GT5 and GT12.
[0138] In the method of the flow chart of FIG. 15, since the heat
medium heated at the heating operation is made to be circulated
into the flow path that prevents freezing, anti-freezing effect can
be expected more than the method of the flow chart of FIG. 13.
However, when some time has elapsed after the stop of the heating
operation, anti-freezing will he less effective.
[0139] In order to further steadily perform anti-freezing in this
case as well, when the temperature equal to or lower than the set
temperature is detected by either the first temperature sensor 31a
or 31b, or the second temperature sensor 32a or 32b, with the pump
21a or 21b being in operation corresponding to the intermediate
heat exchanger 15a or 15b corresponding to the temperature sensor
that detected the temperature equal to or lower than the set
temperature, the compressor 10 is made to operate, the four-way
valve 11 is switched to the heating side, the high-temperature
high-pressure refrigerant is introduced into the intermediate heat
exchanger 15a or 15b corresponding to the temperature sensor that
detected the temperature equal to or lower than the set
temperature, and the heat medium is heated to rise the temperature,
so as to perform anti-freezing.
[0140] FIG. 16 is a flow chart illustrating this operation. Since
from UT0 to UT16 in FIG. 16 are the same as from GT0 to GT16 in
FIG. 15 and regarding the circulation of the heat medium it is the
same as what is explained in the above, descriptions will be
omitted. In FIG. 16, the compressor 10 is operated, the four-way
valve 11 is switched to the heating side, a step (UT19) is added to
guide a high-temperature high-pressure refrigerant to the heating
intermediate heat exchanger 15a. While heating the heating
intermediate heat exchanger 15a by the refrigerant, by circulating
the heat medium, the temperature of the heat medium passing through
the intermediate heat exchangers 15a and 15b is increased and
freezing can be prevented. When the detection temperatures of all
the temperature sensors become higher than the set temperature Ts
(UT16), the pumps 21a and 21b and the compressor 10 are stopped.
(UT17)
[0141] In order to prevent the heat medium from freezing, there is
a method to make the heat medium circulate by operating the pump
like the flow chart of FIGS. 13 and 15. However, when the
temperature of the heat medium further decreases or does not
increase after a certain time elapses even with the method, it is
desirable to judge that anti-freezing is difficult only by
circulating the refrigerant and then operate the compressor to
perform control like the flow chart of FIG. 14 or 16.
[0142] In order to prevent the heat medium from freezing, a flow
path configuration of the heat medium as shown in FIG. 11 is
effective. In FIG. 11, the outlet side of the pump 21b of the
outlet side of the cooling intermediate heat exchanger 15b and the
inlet side of the heating intermediate heat exchanger 15a are
bypass-connected via a bypass stop valve 28a, and the outlet side
of the pump 21a of the outlet side of the heating intermediate heat
exchanger 15a and the inlet side of the cooling intermediate heat
exchanger 15b are bypass-connected via a bypass stop valve 28b.
Then, when the pumps 21a and 21b are made to operate, a flow path
is formed in which the heat medium flows through the cooling
intermediate heat exchanger 15b, the pump 21b, the bypass stop
valve 28a, the heating intermediate heat exchanger 15a, the pump
21a, the bypass stop valve 28b, and the cooling intermediate heat
exchanger 15b in order. Thereby, since the heated heat medium at
the heating intermediate heat exchanger 15a side flows into the
cooling intermediate heat exchanger 15b side, the heat medium in
the flow path of the cooling intermediate heat exchanger 15b is
heated and enabled to be anti-freezing. In case that heat amount is
still not enough, the compressor 10 is operated and the heating
intermediate heat exchanger 15a is heated.
[0143] In the configuration of FIG. 11, since no heat medium flows
through the flow path switching valves 22 (22a to 22d) and 23 (23a
to 23d) and the flow amount adjustment valve 25 (25a to 25d),
mixing of the heat medium can be made small in the heating flow
path and the cooling flow path and heat loss of the heat medium can
be made small when performing heating or cooling in the next
operation. Further, since no pressure loss is created caused by
each valve 22, 23, and 25 and piping, pumping power can be made
small during anti-freezing operation advantageously.
[0144] Descriptions will be given to the operation of the above by
the flow chart of FIG. 17. Here, as the flow path switching valves
22 and 23, anything that can set at an intermediate opening-degree
between full open and full close by a stepping motor or the like
will be used.
[0145] After the processing starts (HTO), the controller 300 judges
whether the detection temperatures of the first temperature sensor
31a or the second temperature sensor 32a related to the
intermediate heat exchanger 15a or the detection temperature of the
first temperature sensor 31b or the second temperature sensor 32b
related to the intermediate heat exchanger 15b are equal to or
lower than the set temperature Ts or not (HT1 to HT4). When the
temperature in the above-mentioned step is detected to be equal to
or lower than the set temperature Ts, the pumps 21a and 21b are
operated (HT5), the bypass stop valves 28a and 28b are made to be
open (HT6), and the heat medium is made to circulate via the bypass
between the intermediate heat exchangers 15a and 15b. The
circulation circuit thereof is shown by a thick line in the heat
medium circuit of FIG. 11.
[0146] Further, in searching from "1" of the indoor unit to the
maximum number of installed units in order (HT7, HT14, HT15), when
the detection temperature of the third temperature sensor 33 is
detected to be equal to or lower than the set temperature Ts (HT8)
or the fourth temperature sensor 34 detects the temperature equal
to or lower than the set temperature Ts (HT9) the pump 21a and the
pump 21b are made to operate (HT10). Then, the flow path switching
valves 22 and 23 of the n-th indoor unit (n) whose temperature is
detected to be equal to or lower than the set temperature are set
at an intermediate opening (HT11). The stop valve 24 of the indoor
unit (n) is made to be open and the flow amount adjustment valve 25
is made to be full open to the use side heat exchanger 26 side
(HT12). The bypass stop valves 28a and 28b are made to be close
(HT13). A flow path is configured to make the heat medium to
circulate to the use side heat exchangers 26a to 26d side.
[0147] When the detection temperatures of all the above-mentioned
temperature sensors become higher than the set temperature Is
(HT16), the pumps 21a and 21b are stopped (HT17), and processing is
terminated (HT18). In HT5 and HT10, either the pump 21a or 21b may
be operated.
[0148] The above mentioned set temperature Ts is set at a
temperature a little higher than a freezing temperature. For
example, if the heat medium is water, Ts may be set at 3 degrees
C., a little higher than the freezing temperature 0 degree C.
[0149] In the anti-freezing operation, a circulation flow path of
the heat medium has to be secured before or at the same time as the
pump 21a or 21b is operated. Therefore, in order to form a heat
medium circulation circuit, after any or all of the stop valves 24a
to 24d are made to be open state, and the flow amount adjustment
valves 25a to 25d are controlled to the direction in which the flow
path is secured, the pump 21a or 21b is made to operate so as to
circulate the heat medium.
[0150] As shown in FIG. 12, as the flow amount adjustment valves
25a to 25d, a two-way flow amount adjustment valve may be used.
Then, the stop valves 24a to 24d need not to be provided. After
controlling the opening-degree of the flow amount adjustment valves
25a to 25d to secure the circulation flow path of the heat medium,
the pumps 21a to 21d are operated.
[0151] In the present embodiment, temperature sensors are installed
at the inlet and outlet of the intermediate heat exchangers 15a and
15b. However, in order to control the pumps 21a and 21b, only
either the inlet temperature or the outlet temperature may be
detected, therefore, the temperature sensor may be installed either
at the inlet or at the outlet.
[0152] The refrigerant may be a single refrigerant such as R-22 and
R-134a, a pseudo-azeotropic mixture refrigerant such as R-410A and
R-404A, an azeotropic mixture refrigerant such as R-407C, a
refrigerant and its mixture that is regarded to have a smaller
global warming potential such as CF.sub.3CF.dbd.CH.sub.2 including
a double bond in the chemical formula, or a natural refrigerant
such as CO.sub.2 and propane.
[0153] Although the refrigerant circuit is configured to contain an
accumulator, a circuit having no accumulator is possible.
Descriptions are given to the case where there are the check valves
13a to 13d, however, they are not an indispensable component, the
present invention can be configured by a circuit without them, and
then the same operation and the same working effect can be
achieved.
[0154] A fan should be attached to the heat source side heat
exchanger 12 and the use side heat exchangers 26a to 26d and it is
preferable to accelerate condensation or evaporation by blowing. It
is not limited thereto, but as for the use side heat exchangers 26a
to 26d, a panel heater utilizing radiation may be used. As for the
heat source side heat exchanger 12, a water-cooled type may be used
that transfers heat by water and anti-freezing liquid. Any type can
be used having a structure that can release or absorb heat.
[0155] Descriptions are given to the case where there are four use
side heat exchangers 26a to 26d, however, there is no limit for the
number of units of the use side heat exchanger.
[0156] Descriptions are given to the case where the flow path
switching valves 22a to 22d and 23a to 23d, the stop valves 24a to
24d, and the flow amount adjustment valves 25a to 25d are connected
with the use side heat exchangers 26a to 26d on a one-by-one basis,
however, it is not limited thereto. Each use side heat exchanger
may be connected with a plurality of them. Then, the flow path
switching valve, the stop valve, and the flow amount adjustment
valve connected to the same use side heat exchanger may be operated
in the same way.
[0157] In the above-mentioned embodiment, descriptions are given to
the case where there are the intermediate heat exchanger 15a for
heating and the intermediate heat exchanger 15b for cooling,
however, it is riot limited thereto. In the case of only heating or
cooling, one intermediate heat exchanger is enough. In that case,
at the time of the anti-freezing operation, no heat medium needs to
be passed through another intermediate heat exchanger, therefore,
the flow path is more simplified. One set or more of the
intermediate heat exchanger 15a for heating and the intermediate
heat exchanger 15b for cooling may be provided.
[0158] In place of the three-way flow path type flow amount
adjustment valves 25a to 25d of FIG. 3, a flow amount adjustment
valve of a two-way flow path adjustment valve may be employed that
can sequentially change the opening area by a stepping motor or the
like as shown in FIG. 12. The control in this case is similar to
the case of the three-way flow path adjustment valve. The opening
of the two-way flow path adjustment valves 25a to 25d is adjusted
to control the flow amount to be flowed into the use side heat
exchangers 26a to 26d so that the difference in temperature between
the inlet and outlet of the use side heat exchangers 26a to 26d
becomes a predetermined target value, for example, 5 degrees C.
Then, the rotation speed of the pumps 21a and 21b may be controlled
so that the inlet side or the outlet side temperature of the
intermediate heat exchangers 15a and 15b becomes a predetermined
target value. When using the two-way flow path adjustment valve as
the flow amount adjustment valves 25a to 25d, since it can he used
for opening and closing the flow path, no stop valves 24a to 24d
are required and low-cost system construction is enabled
advantageously.
[0159] Here, descriptions are given to the case where the flow
amount adjustment valves 25a to 25d, the third temperature sensors
33a to 33d, the fourth temperature sensors 34a to 34d are installed
inside of the relay unit 3, however, it is not limited thereto. If
they are installed near the use side heat exchangers 26a to 26d,
that is, inside of or near the indoor unit 2, there is no
functional problem and the same operation and the same working
effect can be achieved. When employing the two-way flow path
adjustment valve as the flow amount adjustment valves 25a to 25d,
the third temperature sensors 33a to 33d and the fourth temperature
sensors 34a to 34d may be installed inside of or near the relay
unit 3 and the flow amount adjustment valves 25a to 25d may he
installed inside of or near the indoor unit 2.
[0160] As mentioned above, when the temperature of the heat medium
is detected to be equal to or lower than the set temperature, the
air-conditioning apparatus according to the present invention
prevents freezing of the heat medium in pipelines to safely and
steadily achieve energy saving by performing anti-freezing
operation such as operating the pump to circulate the heat
medium.
* * * * *