WO2007108319A1

WO2007108319A1 - Refrigerating apparatus

Info

Publication number: WO2007108319A1
Application number: PCT/JP2007/054405
Authority: WO
Inventors: Shinichi Kasahara; Takahiro Yamaguchi
Original assignee: Daikin Industries, Ltd.
Priority date: 2006-03-22
Filing date: 2007-03-07
Publication date: 2007-09-27
Also published as: KR20080091853A; TR201807246T4; AU2007228237B2; EP1998123A1; EP1998123A4; CN101395435B; CN101395435A; CN101907366B; US20090019879A1; AU2007228237A1; JP2007255750A; CN101907366A; JP4797727B2; EP1998123B1; ES2671446T3; KR100988712B1

Abstract

A refrigerating apparatus including a refrigerant circuit (10) in which such a refrigerating cycle that the pressure of a refrigerant discharged from a compressor (22) is increased to a critical value or higher. When the heating operation is performed in a first indoor heat exchanger (33a) and a second indoor heat exchanger (33b) is stopped to operate, an indoor expansion valve (34b) corresponding to the indoor heat exchanger (33b) being stopped to operate is fully closed.

Description

Specification

Refrigeration equipment

Technical field

TECHNICAL FIELD [0001] The present invention relates to a refrigeration apparatus that enables individual heating operations with a plurality of usage-side heat exchangers, and particularly relates to measures against refrigerant stagnation in a dormant usage-side heat exchanger. Background art

A refrigeration apparatus that performs a refrigeration cycle by circulating a refrigerant is widely applied to air conditioners and the like. As this air conditioner, there is a so-called multi-type air conditioner in which a plurality of indoor units are connected in parallel to an outdoor unit.

[0003] For example, the air conditioner of Patent Document 1 includes one outdoor unit having a compressor and an outdoor heat exchanger (heat source side heat exchanger), and an indoor heat exchanger (use side heat exchanger). With two indoor units. The two branch pipes to which the two indoor heat exchangers are connected are each provided with a motor-operated valve so as to correspond to each indoor heat exchanger.

[0004] In this air conditioner, the heating operation can be individually performed in each indoor unit by controlling the opening degree of each motor-operated valve. Specifically, for example, when performing heating operation simultaneously with two indoor units, both motor-operated valves are opened at a predetermined opening, and refrigerant is actively sent to both indoor heat exchangers. . As a result, heat is released from the refrigerant flowing through the indoor heat exchangers to the indoor air, and each room is heated. On the other hand, for example, when heating operation is performed with only one indoor unit, the motor-operated valve corresponding to the indoor unit on the operation side is opened while the motor-operated valve corresponding to the indoor unit on the pause side is closed. As a result, the refrigerant is sent only to the indoor heat exchanger of the indoor unit on the operation side, and the refrigerant in the indoor heat exchanger radiates heat to the indoor air.

Patent Document 1: JP-A-8-159590

Disclosure of the invention

Problems to be solved by the invention

[0005] By the way, as described above, when only one indoor unit is operated continuously, The refrigerant in the indoor heat exchanger may condense, and the refrigerant may accumulate in the indoor heat exchanger, so-called refrigerant stagnation may occur. Thus, if the refrigerant stagnates in the indoor heat exchanger on the pause side, the amount of refrigerant flowing through the indoor heat exchanger on the operation side (heating operation side) becomes insufficient, and the heating capacity of this indoor unit decreases. End up.

[0006] The present invention has been made in view of the strong point, and an object of the present invention is to prevent the stagnation of the refrigerant in the use side heat exchanger on the dormant side.

Means for solving the problem

[0007] The first invention relates to a heat source side circuit (21) having a compressor (22) and a heat source heat exchanger (23), with respect to the use side heat exchanger (33a, 33b) and the use side heat. A refrigerant circuit (10) configured by connecting a plurality of use side circuits (31a, 31b) each having a motorized valve (34a, 34b) corresponding to the exchanger (33a, 33b) in parallel; It is premised on a refrigeration system that enables individual heat exchangers (33a, 33b) to perform heating operations that also release heat from the refrigerant in the heat exchangers (33a, 33b). The refrigeration apparatus is characterized in that the refrigerant circuit (10) is configured to perform a refrigeration cycle in which the refrigerant discharged from the compressor (22) is at a critical pressure or higher.

[0008] In the refrigeration apparatus according to the first aspect of the present invention, an operation (hereinafter referred to as a full operation) in which all the use side heat exchangers (33a, 33b) perform a heating operation and a part of the use side heat exchangers (33b) ) Is stopped, and at the same time, the operation (hereinafter referred to as “partial operation”) in which the remaining usage-side heat exchanger (33a) performs the heating operation becomes possible.

[0009] Specifically, all the above-described operations can be performed by opening the motor-operated valves (34a, 34b) corresponding to the use side heat exchangers (33a, 33b) to a predetermined opening degree. That is, in full operation, the refrigerant discharged from the compressor (22) flows through each use side heat exchanger (33a, 33b). As a result, heat is also released from the refrigerants flowing through the use side heat exchangers (33a, 33b), and heating operations are performed in the use side heat exchangers (33a, 33b). As a result, for example, each room is heated by each use side heat exchanger (33a, 33b).

[0010] On the other hand, when the heating operation of some of the usage side heat exchangers (33a, 33b) is paused, the usage side heat exchanger (33b) Use side heat exchange with heating operation at the same time that the opening of the motorized valve (3 4b) corresponding to the The opening degree of the motor-operated valve (34a) corresponding to the container (33a) is opened at a predetermined opening degree. As a result, the refrigerant substantially flows only through the use side heat exchanger (33a) on the heating operation side, and the heating operation is not performed on the use side heat exchanger (33b) on the dormant side.

[0011] By the way, when such partial operation is performed, the opening of the rest-side motor-operated valve (34b) is reduced, and the rest-side use-side heat exchanger (33b) The refrigerant accumulates in the tank. Here, for example, when performing a refrigeration cycle in which the discharge pressure of the compressor is a subcritical pressure using a refrigerant such as HFC, the use side heat exchanger (33b) As the ambient temperature also decreases, the refrigerant in the idle-side heat exchanger (33b) gradually condenses. As a result, the refrigerant stagnates in the use side heat exchanger (33b) on the dormant side, resulting in a problem that the amount of refrigerant flowing through the use side heat exchanger (33a) on the heating operation side is insufficient.

[0012] Therefore, in the present invention, the refrigerant discharged from the compressor (22) is set to a critical pressure or higher in order to prevent the refrigerant from stagnation in the idle-side use-side heat exchanger (33b). That is, in the refrigerant circuit (10) of the refrigeration apparatus of the present invention, a refrigeration cycle (so-called supercritical cycle) in which the refrigerant is at a critical pressure or higher is performed. As a result, since the refrigerant in the critical state is stored in the idle side use side heat exchanger (33b) during partial operation, the refrigerant does not condense in the use side heat exchanger (33b). In other words, compared to the conventional one that performs a refrigeration cycle using a refrigerant such as HFC, in the idle side use side heat exchanger (33b) of the present invention, the refrigerant does not change phase, so the use side heat exchanger ( The speed of stagnation of the refrigerant in 33b) is reduced.

[0013] The second aspect of the present invention is the first aspect of the present invention, in performing the operation in which the use side heat exchanger (33a) performing the heating operation and the dormant use side heat exchanger (33b) coexist. And a control means (51) that fully closes the motor-operated valve (34b) corresponding to the use side heat exchanger (33b).

[0014] In the second invention, when performing the partial operation described above, the control means (51) fully closes the motor-operated valve (34b) corresponding to the use side heat exchanger (33b). As a result, the refrigerant accumulates in the idle side use side heat exchanger (33b), but the supercritical cycle is performed as described above. The amount of refrigerant stagnation in the side heat exchanger (33b) is greatly reduced. On the other hand, when the motor-operated valve (34b) is completely closed as described above, the refrigerant flows only through the use side heat exchanger (33a) on the heating operation side. That is, the refrigerant does not flow through the use side heat exchanger (33b) on the dormant side, and wasteful heat radiation is not performed from the use side heat exchanger (33b).

[0016] In a third aspect based on the second aspect, the control means (51) fully closes the motor-operated valve (34b) corresponding to the idle side use-side heat exchanger (33b). When one specified time tl elapses, the motor-operated valve (34b) is temporarily opened for a second specified time t2.

[0017] In the third invention, when the partial operation is performed, the motor-operated valve (34b) corresponding to the idle-side use-side heat exchanger (33b) is fully closed, and then the predetermined first regulation When the time tl has elapsed, the control means (51) opens the motor-operated valve (34b) at a predetermined opening (a relatively small opening is preferred). In other words, when a part of the operation is continuously performed for a long period of time, even if the supercritical cycle as described above is performed, the refrigerant gradually enters the idle side use side heat exchanger (33b). May fall asleep. For this reason, in the partial operation of the present invention, the motor-operated valve (34b) is forcibly opened when the first specified time tl elapses, and the idle side use side heat exchanger (for the second specified time t2) ( The refrigerant is allowed to flow in 33b). As a result, the refrigerant in the idle side use side heat exchanger (33b) flows during the second specified time t2, so that the temperature of the use side heat exchanger (33b) and its surroundings rises and the refrigerant stagnates. Is resolved. Thereafter, when the second specified time t2 elapses, the motor-operated valve (34b) is fully closed again.

[0018] In a fourth invention according to the third invention, each of the use side heat exchangers (33a, 33b) is configured to be disposed indoors and release the heat of the refrigerant to the indoor air. Around the side heat exchangers (33a, 33b), indoor temperature sensors (44, 45) for detecting the indoor temperature corresponding to the respective use side heat exchangers (33a, 33b) are provided, respectively. Correction means (52 for correcting one or both of the first specified time tl and the second specified time t2 based on the detected temperature of the indoor temperature sensor (45) corresponding to the use side heat exchanger (33b) ).

[0019] In the fourth invention, the correcting means (52) determines the first specified time tl and the first time based on the room temperature detected by the room temperature sensor (45) of the dormant use side heat exchanger (33b). 2 One specified time t2 Correct one or both.

[0020] Specifically, for example, when the room temperature around the hibernation-side use-side heat exchanger (33b) is high, the refrigerant stagnates in the hibernation-side use-side heat exchanger (33b). Therefore, in such a case, it is possible to lengthen the time for fully closing the motor-operated valve (34b) by correcting the first specified time tl to be longer or the second specified time t2 to be shorter. it can. As a result, it is possible to avoid the refrigerant from dissipating heat in the idle side use side heat exchanger (33b).

[0021] On the other hand, for example, when the room temperature around the idle side use side heat exchanger (33b) is low, the refrigerant easily stagnates in the idle side use side heat exchanger (33b). Therefore, in such a case, the refrigerant stagnation in the use side heat exchanger (33b) can be performed by correcting the first specified time tl to be shorter or the second specified time t2 to be longer. It can be avoided in advance.

[0022] A fifth invention comprises refrigerant density detection means (40, 41, 42, 43) for detecting refrigerant density in each use side heat exchanger (33a, 33b), and the control means (51 ) Fully closes the motor-operated valve (34b) corresponding to the use side heat exchanger (33b) on the dormant side, and then the refrigerant density detection means (40, 41, When the detected refrigerant density of 43) becomes larger than the specified refrigerant density, the motor-operated valve (34b) is temporarily opened.

[0023] In the fifth aspect of the invention, when the partial operation is performed, the motor-operated valve (34b) corresponding to the idle side use side heat exchanger (33b) is fully closed, and then the idle side use side heat exchange is performed. The refrigerant density in the vessel (33b) is detected by the refrigerant density detecting means (40, 41, 43). That is, the refrigerant detection means (40, 41, 43) indirectly detects the amount of the refrigerant accumulated in the idle side use side heat exchanger (33b) based on the refrigerant density. When the detected refrigerant density becomes larger than the specified refrigerant density, it is considered that a large amount of refrigerant is stored in the idle-side use-side heat exchanger (33b), and the control means (51) is operated by the motor operated valve (34b). Is temporarily released. As a result, the stagnation of the refrigerant in the use side heat exchanger (33b) on the dormant side can be avoided beforehand.

[0024] The sixth invention is characterized in that, in any one of the first to fifth power 4 inventions, the refrigerant circuit (10) is filled with carbon dioxide as a refrigerant. .

[0025] In the sixth invention, a supercritical cycle using carbon dioxide is performed in the refrigerant circuit (10).

[0026] A seventh invention is the invention of any one of the second to fifth powers 4, wherein each use side heat exchanger (33a , 33b) and an opening / closing mechanism that can open and close each of the air outlets, and each of the opening / closing mechanisms includes a blower of the use side heat exchanger (33b) that performs a heating operation. The outlet is configured to be closed while the outlet of the use side heat exchanger (33a) on the dormant side is closed.

[0027] In the refrigeration apparatus according to the seventh aspect of the present invention, a plurality of blower loca- tions are provided corresponding to each use side heat exchanger (33a, 33b). Each air outlet is provided with an opening / closing mechanism for opening or closing the air outlet. Here, in all operations, the open / close mechanisms of all the air outlets are opened, and the air heated by the respective use side heat exchangers (33a, 33b) is blown out from the air outlets into the room or the like. On the other hand, in the partial operation, the opening / closing mechanism of the outlet side of the heating-side heat exchanger (33a) is opened, while the opening / closing mechanism of the outlet-side heat exchanger (33b) is closed. Closed state. As a result, in the use side heat exchanger (33b) on the dormant side, it is possible to prevent the heat of the refrigerant inside it from escaping to another space such as a room through the blowout port. For this reason, it is possible to suppress a decrease in the ambient temperature of the use side heat exchanger (33b) on the dormant side, and to effectively avoid stagnation of the refrigerant in the use side heat exchanger (33b).

The invention's effect

[0028] In the present invention, in a refrigeration apparatus capable of individually performing heating operations with a plurality of usage-side heat exchangers (33a, 33b), the refrigerant discharged from the compressor (22) exceeds the critical pressure. A critical cycle is performed. For this reason, even if the opening degree of the motor-operated valve (34b) on the suspension side is set to a very small opening or a fully closed state during the partial operation described above, the refrigerant will stagnate in the utilization side heat exchanger (33a, 33b) on the suspension side. Become. Therefore, according to the present invention, it is possible to eliminate the shortage of the amount of refrigerant flowing through the use side heat exchanger (33a) on the heating operation side, and the heating capability of the use side heat exchanger (33a) on the heating operation side is sufficiently high. Can get to.

[0029] In particular, in the second invention, the rest-side motor operated valve (34b) is fully closed when performing partial operation. Therefore, according to the second aspect of the invention, since all the refrigerant is sent to the heating-side use-side heat exchanger (33a), wasteful heat dissipation is performed by the dormant-side use-side heat exchanger (33b). Can be avoided. Therefore, according to the present invention, it is possible to improve the heating capacity of the use-side heat exchanger (33a) on the heating side, and to improve the COP (coefficient of performance) of this refrigeration apparatus. [0030] In addition, in the third invention, the motor-operated valve (34b) that is once fully closed when performing a partial operation is opened only during the second specified time t2 after the first specified time tl has elapsed. Yes. Therefore, according to the third aspect of the present invention, it is possible to reliably eliminate the stagnation of the refrigerant in the idle-side heat exchanger (33b) when part of the operation is continued for a long time. The reliability of the refrigeration equipment can be ensured.

[0031] In particular, in the fourth invention, during the partial operation, the first specified time tl and the second specified time t2 are corrected based on the room temperature around the inactive use side heat exchanger (33b). It is doing so. For this reason, according to the fourth aspect of the invention, it is ensured that the fully closed time of the motor-operated valve (34b) becomes longer than necessary, and the refrigerant stagnates in the idle side use side heat exchanger (33b). Can be avoided. In addition, according to the fourth aspect of the present invention, it is ensured that the open time of the motor-operated valve (34b) becomes longer than necessary, and wasteful heat dissipation is performed in the idle side heat exchanger (33b). Can be avoided.

[0032] In the fifth aspect of the invention, the refrigerant density in the idle-side heat exchanger (33b) is detected during partial operation, and the refrigerant density becomes larger than the specified refrigerant density. The motor-operated valve (34b) that has been fully closed is temporarily opened. That is, in the fifth aspect of the invention, the amount of refrigerant stored in the idle-side use-side heat exchanger (33b) is indirectly obtained, and the motor-operated valve (34b) is opened when the amount of refrigerant increases. Accordingly, it is possible to reliably avoid the stagnation of the refrigerant in the idle side use side heat exchanger (33b).

[0033] Furthermore, according to the sixth invention, by using carbon dioxide as the refrigerant, it is possible to perform a supercritical cycle using a natural refrigerant having a relatively low critical temperature.

[0034] Further, according to the seventh aspect of the invention, since the outlet of the idle side use side heat exchanger (33b) is closed by the opening / closing mechanism during partial operation, the use side heat exchanger The decrease in the ambient temperature of (33b) can be suppressed, and the refrigerant stagnation in the use side heat exchanger (33b) can be more effectively avoided.

Brief Description of Drawings

FIG. 1 is a piping system diagram of a refrigerant circuit of an air conditioner according to an embodiment.

[FIG. 2] FIG. 2 is a piping system diagram showing the refrigerant flow in the refrigerant circuit during all heating operations.

FIG. 3 is a piping diagram showing the refrigerant flow in the refrigerant circuit during partial heating operation. FIG. 4 is a PH diagram (Mollier diagram) of the supercritical cycle according to the embodiment.

FIG. 5 is a PH diagram (Mollier diagram) of a refrigeration cycle according to a conventional example.

FIG. 6 is a piping diagram showing the refrigerant flow in the refrigerant circuit during partial heating operation of an air conditioner according to a modification.

7] FIG. 7 is a graph showing the behavior of changes in refrigerant density and refrigerant temperature from the inlet to the outlet of the pause-side indoor heat exchanger in the embodiment.

FIG. 8 is a graph showing the behavior of changes in the refrigerant density and refrigerant temperature from the inlet to the outlet of the idle indoor heat exchanger in the conventional example.

Explanation of symbols

1 Air conditioner (refrigeration equipment)

10 Refrigerant circuit

21 Outdoor circuit (heat source side circuit)

22 Compressor

23 Outdoor heat exchanger (heat source side heat exchanger)

3ύ & 1st indoor heat exchanger (use side heat exchanger)

33b Second indoor heat exchanger (use side heat exchanger)

34a 1st indoor expansion valve (motorized valve)

34b Second indoor expansion valve (motorized valve)

44 1st room temperature sensor (room temperature sensor)

45 Second room temperature sensor (room temperature sensor)

51 Control means

52 Correction method

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0038] The refrigeration apparatus according to the embodiment constitutes a so-called multi-type air conditioner (1) capable of heating and cooling a room. As shown in FIG. 1, this air conditioner (1) includes one outdoor unit (20) installed outdoors, and first and second indoor units (30a, 30a, 30) installed in different rooms. 30b). [0039] The outdoor unit (20) is provided with an outdoor circuit (21) constituting a heat source side circuit. The first indoor unit (30a) includes a first indoor side circuit (31a) that constitutes a use side circuit, and the second indoor unit (30b) includes a second indoor side circuit (31b that constitutes a use side circuit). ) Are provided.

[0040] Each indoor circuit (31a, 31b) is connected in parallel to the outdoor circuit (21) via the first connection pipe (11) and the second connection pipe (12). As a result, in the air conditioner (1), the refrigerant circuit (10) is configured in which the refrigerant circulates and the refrigeration cycle is performed. This refrigerant circuit (10) is filled with carbon dioxide as a refrigerant.

[0041] The outdoor circuit (21) is provided with a compressor (22), an outdoor heat exchanger (23), an outdoor expansion valve (24), and a four-way switching valve (25). The compressor (22) is a fully-enclosed high-pressure dome type scroll compressor. Electric power is supplied to the compressor (22) via an inverter. That is, the capacity of the compressor (22) can be changed by changing the rotational speed of the compressor motor by changing the output frequency of the inverter. The outdoor heat exchanger (23) is a cross-fin type fin 'and' tube heat exchanger and constitutes a heat source side heat exchanger. In the outdoor heat exchanger (23), heat is exchanged between the refrigerant and the outdoor air. The outdoor expansion valve (24) is an electronic expansion valve whose opening degree can be adjusted.

[0042] The four-way selector valve (25) has first to fourth ports. The four-way selector valve (25) has a first port connected to the discharge pipe (22a) of the compressor (22), a second port connected to the outdoor heat exchanger (23), and a third port connected to the compressor. It is connected to the suction pipe (22b) of (22), and the fourth port is connected to the first connection pipe (11). The four-way selector valve (25) has a state in which the first port and the fourth port communicate with each other and the second port and the third port communicate with each other (indicated by a solid line in FIG. 1), the first port, The second port communicates with each other, and the third port and the fourth port communicate with each other (shown by a broken line in FIG. 1).

[0043] The first indoor circuit (31a) is provided with a first branch pipe (32a) having one end connected to the first connecting pipe (11) side and the other end connected to the second connecting pipe (12) side. I'm going. The first branch pipe (32a) is provided with a first indoor heat exchanger (33a) and a first indoor expansion valve (34a). The second chamber inner circuit (31b) is provided with a second branch pipe (32b) having one end connected to the first connecting pipe (11) side and the other end connected to the second connecting pipe (12) side. The second branch pipe (32b) Two indoor heat exchangers (33b) and a second indoor expansion valve (34b) are provided.

[0044] Each indoor heat exchanger (33a, 33b) is a cross-fin type fin-and-tube heat exchanger, and constitutes a use side heat exchanger. In each indoor heat exchanger (33a, 33b), heat is exchanged between the refrigerant and room air.

[0045] The first indoor expansion valve (34a) and the second indoor expansion valve (34b) are motor-operated valves, and respectively constitute electronic expansion valves whose opening degrees can be adjusted. The first indoor expansion valve (3½) is provided on the second connecting pipe (12) side of the first branch pipe (32a). The second indoor expansion valve (34b) is provided on the second connecting pipe (12) side of the second branch pipe (32b). The first indoor expansion valve (34a) can adjust the flow rate of the refrigerant flowing through the first indoor heat exchanger (33a), and the second indoor expansion valve (34b) can adjust the second indoor heat exchanger (33b). The flow rate of the refrigerant flowing through can be adjusted.

[0046] The refrigerant circuit (10) is provided with a high pressure sensor (40), a high pressure temperature sensor (41), a first refrigerant temperature sensor (42), and a second refrigerant temperature sensor (43). . The high pressure sensor (40) detects the pressure of the refrigerant discharged from the compressor (22). The high pressure temperature sensor (41) detects the temperature of the refrigerant discharged from the compressor (22). The first refrigerant temperature sensor (42) is provided at the outlet of the first indoor heat exchanger (33a), and detects the temperature of the refrigerant immediately after flowing out of the first indoor heat exchanger (33a). The second refrigerant temperature sensor (43) is provided at the outlet of the second indoor heat exchanger (33b), and detects the temperature of the refrigerant immediately after flowing out of the second indoor heat exchanger (33b).

[0047] The first indoor unit (30a) is provided with a first indoor temperature sensor (44) in the vicinity of the first indoor heat exchanger (33a). The first indoor temperature sensor (44) detects the air temperature around the first indoor heat exchanger (33a). The second indoor unit (30b) is provided with a second indoor temperature sensor (45) in the vicinity of the second indoor heat exchanger (33b). The second indoor temperature sensor (45) detects the air temperature around the second indoor heat exchanger (33b).

[0048] In the refrigerant circuit (10) of the air conditioner (1) of the present embodiment, a refrigeration cycle (supercritical cycle) is performed by setting the refrigerant discharged from the compressor (22) to a critical pressure or higher. Further, in this air conditioner (1), the first indoor unit (30a) and the second indoor unit (30b) can be operated individually. In other words, in this air conditioner (1), the first indoor unit (30a) is heated while the second indoor unit (30b) is in a dormant state (hereinafter referred to as partial heating operation). Can be operated in both the first indoor unit (30a) and the second indoor unit (30b) (hereinafter, all referred to as heating operation).

Furthermore, the air conditioner (1) is provided with a controller (50) for controlling the opening degree of each indoor expansion valve (34a, 34b) in the partial heating operation. The controller (50) is provided with a control means (51) and a correction means (52). Details of the opening control of the indoor expansion valves (34a, 34b) by the controller (50) will be described later.

[0050] One operation

Next, the operation of the air conditioner (1) according to this embodiment will be described. In the air conditioner (1), it is possible to perform an operation in which heating is performed in each indoor unit (30a, 30b) and an operation in which cooling is performed in each indoor unit (30a, 30b). Hereinafter, the heating operation of the air conditioner (1) will be described. In this heating operation, the four-way selector valve (25) is set to the state shown in FIGS. 2 and 3, and the above-described full heating operation and partial heating operation are switched.

[0051] All heating operation>

In the full heating operation, the first indoor expansion valve (34a) and the second indoor expansion valve (34b) are opened at a predetermined opening. As shown in FIG. 2, the refrigerant compressed to the critical pressure or higher by the compressor (22) passes through the four-way switching valve (25) and the first connection pipe (11), and the first branch pipe (32a) and Split to the second branch pipe (32b).

[0052] The refrigerant flowing into the first branch pipe (32a) flows through the first indoor heat exchanger (33a). In the first indoor heat exchanger (33a), the refrigerant releases heat to the indoor air. That is, in the first indoor heat exchanger (33a), a heating operation for heating the room air is performed, and the room in which the first indoor unit (30a) is installed is heated. The refrigerant flowing out of the first indoor heat exchanger (33a) passes through the first indoor expansion valve (34a) and flows into the second connecting pipe (12).

[0053] On the other hand, the refrigerant flowing into the second branch pipe (32b) flows through the second indoor heat exchanger (33b).

In the second indoor heat exchanger (33b), the refrigerant releases heat to the indoor air. That is, in the second indoor heat exchanger (33b), a heating operation for heating the room air is performed, and the room in which the second indoor unit (30b) is installed is heated. The refrigerant flowing out of the second indoor heat exchanger (33b) passes through the second indoor expansion valve (34b) and flows into the second connection pipe (12). [0054] The refrigerant joined in the second communication pipe (12) is reduced in pressure when passing through the outdoor expansion valve (24) and flows through the power outdoor heat exchanger (23). In the outdoor heat exchanger (23), the refrigerant absorbs heat from the outdoor air and evaporates. The refrigerant flowing out of the outdoor heat exchanger (23) is sucked into the compressor (22) via the four-way switching valve (25). In the compressor (22), this refrigerant is compressed to a critical pressure or higher.

[0055] Partial heating operation>

In the partial heating operation, the heating operation of the second indoor heat exchanger (33b) is stopped at the same time as the heating operation of the first indoor heat exchanger (33a), or the second indoor heat exchanger (33b) is used. At the same time that the heating operation is performed, an operation for stopping the heating operation of the first indoor heat exchanger (33a) is performed. Here, a description will be given with reference to FIG. 3 on behalf of an operation in which the heating operation is performed only by the first indoor heat exchanger (33a).

[0056] In this partial heating operation, the controller (51) of the controller (50) opens the first indoor expansion valve (34a) at a predetermined opening, while the second indoor expansion valve (34b) is fully opened. Set to the closed state. When the first indoor expansion valve (34a) is opened, the first indoor heat exchanger (33a) performs the heating operation as described above. On the other hand, when the second indoor expansion valve (34b) is fully closed, the refrigerant does not pass through the second indoor expansion valve (34b). Accordingly, the refrigerant does not circulate through the second indoor heat exchanger (33b), and the second indoor heat exchanger (33b) enters a dormant state.

[0057] When the second indoor heat exchanger (33b) is suspended as described above, the refrigerant gradually accumulates in the second indoor heat exchanger (33b). However, in the air conditioner (1) of the present embodiment, a supercritical cycle in which the refrigerant discharged from the compressor (22) is at a critical pressure or higher is performed even in the partial heating operation. Therefore, even if the ambient temperature of the second indoor heat exchanger (33b) decreases due to the suspension of the second indoor heat exchanger (33b), the refrigerant in the second indoor heat exchanger (33b) Does not condense. Accordingly, the rate at which the refrigerant stagnates in the second indoor heat exchanger (33b) is significantly slower than that in which a subcritical refrigeration cycle is performed using, for example, HFC.

This will be described in more detail with reference to FIGS. 4 and 5. Fig. 4 shows the PH diagram of the supercritical cycle using carbon dioxide of this embodiment, and Fig. 5 shows the P_H diagram of the subcritical refrigeration cycle using conventional HFC. Each is shown. In the conventional one shown in FIG. 5, the pressure of the refrigerant discharged from the compressor becomes smaller than the critical pressure. Specifically, the refrigerant after compression in this refrigeration cycle has, for example, a pressure of 2.7 MPa, a temperature of 80 ° C., and a refrigerant density p of 85 kg / m ³ . On the other hand, this refrigerant is an indoor heat exchanger

1

When condensed, the condensed refrigerant has a pressure of 2.7 MPa, a temperature of 37 ° C, and a refrigerant density P power of 996 kg / m ³ . In other words, in the conventional refrigeration cycle, the outlet side of the indoor heat exchanger

2

The density ratio / p) of the refrigerant density P and the refrigerant density p on the inlet side is 11.72.

2 1 2 1

On the other hand, in the present embodiment shown in FIG. 4, the pressure of the refrigerant discharged from the compressor is equal to or higher than the critical pressure. Specifically, the refrigerant after compression in this cycle has, for example, a pressure of 10 MPa, a temperature of 80 ° C., and a refrigerant density p force of 21 kgZm ³ . On the other hand, this refrigerant is released by the indoor heat exchanger.

1

When heated, the refrigerant after heat dissipation has a pressure of 10 MPa, a temperature of 35 ° C, and a refrigerant density p of

2

The 713kgZm ^3. That is, in the supercritical cycle of the present embodiment, the density ratio / p) between the refrigerant density P on the outlet side of the indoor heat exchanger and the refrigerant density p on the inlet side is 3.23.

2 1 2 1

[0061] As described above, the density ratio before and after the indoor heat exchanger / p between the conventional one and the present embodiment.

twenty one

), The density ratio of the conventional one is more than three times that of the present embodiment. In other words, in the conventional refrigeration cycle, when the refrigerant condenses in the indoor heat exchanger on the dormant side, the refrigerant becomes high density and the volume decreases, so that the refrigerant is successively sent to the indoor heat exchanger. Become. Therefore, in the conventional system, the refrigerant stagnates in the indoor heat exchanger on the pause side, and the speed is relatively high.

[0062] In contrast, in the present embodiment, even if the refrigerant dissipates heat in the pause-side indoor heat exchanger, the volume of the refrigerant is not so small because the refrigerant has a relatively low density. Therefore, the refrigerant is not sent so much into the indoor heat exchanger, and as a result, the refrigerant stagnates in the inactive indoor heat exchanger and the speed is relatively slow.

[0063] On the other hand, if such partial heating operation is continued for a long period of time, the amount of refrigerant stagnation in the second indoor heat exchanger (33b) also increases. Therefore, the control means (51) of the present embodiment starts the partial heating operation and sets the second indoor expansion valve (34b) to the fully closed state, and when the first specified time tl has elapsed, The opening of (34b) is opened at a very small opening for the second specified time t2. In this way, the refrigerant flows through the second indoor heat exchanger (33b) at a minute flow rate, and the temperature of the second indoor heat exchanger (33b) and its surroundings are reduced. To rise. As a result, the stagnation of the refrigerant in the second indoor heat exchanger (33b) is eliminated. Thereafter, when the second specified time t2 has elapsed, the control means (51) again closes the second indoor expansion valve (34b).

[0064] Further, after the partial heating operation is started and the second indoor expansion valve (34b) is fully closed, the amount of the refrigerant that stagnates in the second indoor heat exchanger (33b) Depends on the ambient temperature of the exchanger (33b). In other words, when the temperature of the room where the second indoor heat exchanger (33b) is installed is relatively low, the refrigerant stagnates in the second indoor heat exchanger (33b) and the speed increases. When the room temperature is relatively high, the refrigerant stagnates and the speed decreases. For this reason, the correction means (52) of the controller (50) of the present embodiment detects the room temperature around the pause-side indoor heat exchanger (33b) with the room temperature sensor (45), and this room temperature is detected. Based on this, the first specified time tl and the second specified time t2 are corrected.

[0065] Specifically, if the detected indoor temperature of the second indoor temperature sensor (45) is relatively low at the start of the partial heating operation, the correcting means (52) corrects to shorten the first specified time tl. Do. Further, when the detected room temperature of the second room temperature sensor (45) is relatively low when the first specified time tl has elapsed, the correction means (52) performs correction to increase the second specified time t2. As a result, the time for which the second indoor expansion valve (34b) is fully closed is shortened during partial heating operation, so that it is possible to prevent the refrigerant from sleeping in the second indoor heat exchanger (33b). Can be resolved. Note that the correction of the first specified time tl and the second specified time t2 may be either one or both.

On the other hand, when the detected indoor temperature of the second indoor temperature sensor (45) is relatively high at the start of the partial heating operation, the correcting means (52) performs a correction to increase the first specified time tl. Further, when the detected room temperature of the second room temperature sensor (45) is relatively high when the first specified time tl has elapsed, the correcting means (52) performs correction to shorten the second specified time t2. As a result, the time required for opening the second indoor expansion valve (34b) in the partial heating operation is shortened, so that wasteful heat radiation is not performed in the second indoor heat exchanger (33b) on the pause side. .

[0067] Advantages of one embodiment

In the above embodiment, in the air conditioner (1) that can be individually heated by the plurality of indoor heat exchangers (33a, 33b), the refrigerant discharged from the compressor (22) is set to a critical pressure or higher. The supercritical cycle is performed. For this reason, the refrigerant will not condense in the inactive indoor heat exchanger (33b) even when the opening of the inactive indoor expansion valve (34b) is fully closed during partial heating operation. Therefore, according to the above-described embodiment, it is possible to drastically reduce the cooling speed when the cooling medium stagnates in the inactive indoor heat exchanger (33b). As a result, the shortage of refrigerant in the indoor heat exchanger (33a) during the heating operation can be avoided, and the heating capacity of the indoor heat exchanger (33a) on the heating operation side can be sufficiently obtained.

[0068] In the above-described embodiment, the indoor expansion valve (34b) on the pause side is fully closed when performing a partial heating operation. For this reason, according to the said embodiment, useless heat dissipation in the indoor heat exchanger (33b) of a dormant side can be prevented. Therefore, the COP (performance factor) of the air conditioner (1) can be improved.

[0069] Further, in the above embodiment, the indoor expansion valve (34b), which is once fully closed when performing the partial heating operation, is opened only for the second specified time t2 after the first specified time tl has elapsed. ing. Therefore, according to the above-described embodiment, even when partial heating operation is continuously performed for a long period of time, it is possible to reliably eliminate the stagnation of the refrigerant in the inactive indoor heat exchanger (33b). In addition, it is possible to reliably prevent the refrigerant amount from being insufficient in the indoor heat exchanger (33a) during the heating operation.

[0070] Further, in the above embodiment, during the partial heating operation, the first specified time tl and the second specified time t2 are corrected based on the room temperature around the inactive indoor heat exchanger (33b). I am doing so. For this reason, according to the above embodiment, it is possible to prevent the indoor expansion valve (34b) from being fully closed longer than necessary, and the refrigerant from sleeping in the inactive indoor heat exchanger (33b). . Further, according to the above embodiment, the open time of the indoor expansion valve (34b) becomes longer than necessary, and heat is discharged wastefully in the refrigerant heat in the indoor heat exchanger (33b) on the pause side. Can be avoided. Therefore, it is possible to further improve the COP of the air conditioner (1).

[0071] Modified example of opening control of one indoor expansion valve

In the above embodiment, during the partial heating operation, after the indoor expansion valves (33a, 33b) on the pause side are fully closed, the indoor expansion valves (33a, 33b) are set based on the first specified time tl and the second specified time t2. 34b) is opened and closed. However, the opening control of such an indoor expansion valve (34b) Instead, the opening degree of the indoor expansion valve (34b) may be controlled as shown in FIG.

[0072] In the partial heating operation of this modification, the refrigerant pressure detected by the high pressure sensor (40), the refrigerant temperature detected by the high pressure sensor (41), and the refrigerant temperature detected by the first refrigerant temperature sensor (42). And the refrigerant temperature detected by the second refrigerant temperature sensor (43) are output to the controller (50). Then, in this controller (50), the density of the refrigerant flowing through the pause-side indoor heat exchanger (33b) in the partial heating operation is determined based on the detection values of these sensors (40, 41, 42, 43). As you ask. That is, each of the sensors (40, 41, 42, 43) constitutes a refrigerant density detecting means for detecting the refrigerant density of the indoor heat exchanger (33b) on the pause side.

Specifically, for example, when performing a partial heating operation similar to that in the above embodiment, the control means (51) first sets the opening of the second indoor expansion valve (34b) to a fully closed state. On the other hand, when this partial heating operation is continued for a long period of time, the refrigerant gradually stagnates in the second indoor heat exchanger (33b).

Here, in the control means (51) of this modification, the refrigerant density in the second indoor heat exchanger (33b) on the pause side is obtained from the refrigerant pressure and the refrigerant temperature. Specifically, for example, when the second indoor heat exchanger (33b) is on the idle side, the refrigerant pressure detected by the controller (50) force high pressure sensor (40) and the high pressure temperature sensor (41) are detected. The refrigerant density in the second indoor heat exchanger (33b) is obtained based on the refrigerant temperature and the refrigerant temperature detected by the second refrigerant temperature sensor (43) on the pause side. That is, the refrigerant pressure detected by the high pressure sensor (40) is substantially the same as the refrigerant pressure in the second indoor heat exchanger (33b). On the other hand, the refrigerant temperature detected by the high-pressure temperature sensor (41) can be regarded as the refrigerant temperature flowing into the second indoor heat exchanger (33b), and the refrigerant temperature detected by the second refrigerant temperature sensor (43). Is the refrigerant temperature flowing out of the second indoor heat exchanger (33b). Therefore, the average temperature of the refrigerant in the indoor heat exchanger (33b) can be obtained from these inflow and outflow refrigerant temperatures. Then, the average refrigerant density of the refrigerant in the second indoor heat exchanger (33b) can be obtained from the average refrigerant temperature and the refrigerant pressure.

[0075] The refrigerant density obtained as described above serves as an index representing the amount of refrigerant stored in the second indoor heat exchanger (33b). And the control means (51) of this modification partly starts the heating operation. After the second indoor expansion valve (34b) is fully closed, if the refrigerant density obtained from the detected values of the sensors (40, 41, 43) exceeds the specified refrigerant density, the second indoor heat exchanger (33b ) The second indoor expansion valve (34b) is temporarily opened because it is determined that a large amount of refrigerant is stored in the inside. As a result, the stagnation of the refrigerant in the second indoor heat exchanger (33b) is reliably eliminated.

[0076] In the partial heating operation in which the first indoor heat exchanger (33a) is stopped and the second indoor heat exchanger (33b) performs the heating operation, the high pressure sensor (40), the high pressure sensor ( 41) and the refrigerant density in the first indoor heat exchanger (33a) are obtained based on the detected value of the first refrigerant temperature sensor (42) on the rest side. In this case, when the refrigerant density becomes larger than the specified refrigerant density, the first indoor expansion valve (34a) is opened, and the stagnation of the refrigerant in the first indoor heat exchanger (33a) is eliminated.

[0077] Effect of one modification

In this modification, during partial heating operation, the refrigerant density in the inactive indoor heat exchanger (33b) is detected, and when this refrigerant density becomes greater than the specified refrigerant density, The expansion valve (34b) is temporarily opened. That is, in this modification, the amount of refrigerant stored in the indoor heat exchanger (33b) on the rest side is obtained indirectly, and the indoor expansion valve (34b) is opened when the amount of refrigerant increases. Therefore, it is possible to reliably avoid the stagnation of the refrigerant in the inactive indoor heat exchanger (33b).

[0078] Further, even in this modification, even in a partial heating operation, by performing a supercritical cycle in the refrigerant circuit (10), each indoor heat exchanger (33a, 33b) on the dormant side is operated. The speed at which the refrigerant sleeps can be greatly reduced.

[0079] Further, when the supercritical cycle is performed in the refrigerant circuit (10) in this way, the indoor heat exchanger on the dormant side is performed.

The average refrigerant density of (33b) can also be grasped more accurately. Specifically, for example, as shown in FIG. 8, the refrigerant density from the inlet to the outlet of a conventional indoor heat exchanger (which performs a refrigeration cycle in which high pressure becomes subcritical pressure) is measured. Looking at the change in (refrigerant temperature), the behavior of the change is weak in linearity. This is because in the conventional system, the refrigerant condenses and changes phase in the indoor heat exchanger on the idle side. Therefore, to accurately grasp the amount of refrigerant stored in the indoor heat exchanger, it is necessary to detect the refrigerant density (refrigerant temperature) at multiple locations (for example, three or more points). Too much.

[0080] On the other hand, as shown in FIG. 7, when the change in refrigerant density (refrigerant temperature) from the inlet to the outlet of the pause-side indoor heat exchanger (33b) of this embodiment is seen, The behavior of change is relatively linear. This is because, in the present embodiment, refrigerant having a critical pressure or higher is stored in the indoor heat exchanger (33b), so that the refrigerant in the indoor heat exchanger (33b) does not change in phase from the inlet to the outlet. Therefore, in this embodiment, the refrigerant density at the inlet and the outlet is obtained as in the above-described modification example, so that the data table stored in the controller (50) in advance (the refrigerant density is related to the behavior of the refrigerant temperature change). Based on data, etc., it is possible to accurately predict the behavior of refrigerant density from the inlet to the outlet of the indoor heat exchanger (33b) to the outlet. Then, based on the refrigerant density thus obtained, the timing of opening the indoor expansion valves (34a, 34b) is determined, so that the stagnation of the refrigerant in the inactive indoor heat exchanger (33b) can be further ensured. It can be avoided.

[0081] << Other Embodiments >>

In the air conditioner (1) according to the above-described embodiment, a louver or the like that can freely open and close each outlet is provided at each outlet from which air that has passed through each use-side heat exchanger (33a, 33b) is blown out. An opening / closing mechanism may be provided. Then, during the partial operation as described above, only the outlet corresponding to the use side heat exchanger (33b) on the pause side may be closed by the opening / closing mechanism. In this case, it is possible to suppress the heat of the refrigerant accumulated in the use side heat exchanger (33b) on the dormant side from escaping into the indoor space via the blowout port. Therefore, a decrease in the ambient temperature of the use side heat exchanger (33b) can be suppressed, and the stagnation of the refrigerant in the use side heat exchanger (33b) can be more effectively avoided. It is to be noted that a sealing material such as packing is preferably provided around the louver in the opening / closing mechanism such as a louver in order to improve the sealing performance when the outlet is sealed.

[0082] The above embodiments are essentially preferable examples, and are not intended to limit the scope of the present invention, its application, or its use.

Industrial applicability

[0083] As described above, the present invention is effective as a countermeasure against the stagnation of the refrigerant in the dormant use side heat exchanger in the refrigerating apparatus that can individually perform the heating operation with the plurality of use side heat exchangers. It is for.

Claims

The scope of the claims

[1] With respect to the heat source side circuit having the compressor and the heat source heat exchanger, a plurality of usage side circuits each having a usage side heat exchanger and an electric valve corresponding to the usage side heat exchanger are connected in parallel. A refrigeration apparatus comprising a refrigerant circuit configured to allow heating operation to release heat from the refrigerant in the use side heat exchanger individually in each use side heat exchanger,

The refrigerant circuit is configured to perform a refrigeration cycle in which a refrigerant discharged from a compressor has a critical pressure or higher.

[2] In claim 1,

A control means is provided for fully closing the motor-operated valve corresponding to the idle-side use-side heat exchanger when performing operation in which the use-side heat exchanger performing the heating operation and the dormant use-side heat exchanger coexist. A refrigeration apparatus characterized by that.

[3] In claim 2,

The control means opens the motorized valve temporarily for the second specified time t2 when the first specified time tl elapses after the motorized valve corresponding to the use side heat exchanger on the idle side is fully closed. A refrigeration system characterized by this.

[4] In claim 3,

Each of the use side heat exchangers is arranged indoors and is configured to release the heat of the refrigerant to the indoor air.

An indoor temperature sensor that detects the temperature of the room corresponding to each usage-side heat exchanger is provided around each usage-side heat exchanger.

Provide correction means for correcting one or both of the first specified time tl and the second specified time t2 based on the detected temperature of the indoor temperature sensor corresponding to the use side heat exchanger on the dormant side. A refrigeration apparatus characterized by.

[5] In claim 2,

Refrigerant density detection means for detecting the refrigerant density in each user-side heat exchanger is provided, and the control means fully closes the motor-operated valve corresponding to the idle-side user-side heat exchanger and then uses the user-side heat exchange. A refrigerating apparatus characterized in that the motor-operated valve is temporarily opened when a refrigerant density detected by a refrigerant density detecting means corresponding to the container becomes larger than a specified refrigerant density.

[6] In any force 1 of claims 1 to 5,

The refrigerating apparatus, wherein the refrigerant circuit is filled with carbon dioxide as a refrigerant.

[7] In any force 4 of claims 2 to 5,

An air outlet through which each of the air passing through each use-side heat exchanger is blown, and an opening / closing mechanism that can open and close the air outlet,

Each of the open / close mechanisms is configured to open the outlet of the use side heat exchanger that performs the heating operation, and close the outlet of the use side heat exchanger on the idle side. apparatus.