JP4179595B2 - Air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air conditioner having a vapor compressor type heat pump cycle, and is particularly suitable for improving operating efficiency and saving energy.
[0002]
[Prior art]
Conventionally, in an air conditioner, in order to realize a high performance coefficient operation in a wide capacity range, it is known to provide an injection circuit and select an operation with a higher performance coefficient among injection operation or non-injection operation, for example, This is described in JP-A-10-176866.
In addition, when a small amount of liquid refrigerant is mixed during gas injection, the efficiency of the compressor is improved due to the cooling effect of the compressor, and energy saving is improved. Therefore, the opening of the two expansion valves in the gas injection cycle It is known that the injection pressure in the gas-liquid separator is increased to mix the liquid refrigerant with the injection gas refrigerant, which is described in, for example, Japanese Patent Application Laid-Open No. 2001-116373.
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-116373
[Problems to be solved by the invention]
In the above-described prior art, liquid refrigerant is mixed at the time of gas injection by expansion valve control in the case of a multi-type in which a plurality of indoor units are connected to one outdoor unit, or a connection pipe between the outdoor unit and the indoor unit When the length is long, the influence of pressure loss in the pipe becomes large, the margin of pressure reduction adjustment of the expansion valve becomes small, and it is not always easy to create an appropriate liquid refrigerant mixed state.
[0004]
An object of the present invention is to provide an air conditioner that can be operated with high energy efficiency and good cycle efficiency (coefficient of performance: COP) regardless of the cycle operation state and cycle configuration.
Furthermore, an object of the present invention is to provide an air conditioner that improves the efficiency in accordance with the actual conditions of use environment and can operate with a high coefficient of performance (high energy saving performance) throughout the year.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an air conditioner having a refrigeration cycle in which a compressor, a heat source side heat exchanger, a first pressure reducing device, a receiver, a second pressure reducing device, and a use side heat exchanger are sequentially connected by piping. An injection circuit connected to the upper part of the receiver for taking out the gas refrigerant in the receiver and connected to the compressor, and connected to the injection circuit for taking out the liquid refrigerant in the receiver. A liquid refrigerant extraction pipe, and a flow rate adjusting valve provided in the liquid refrigerant extraction pipe ,
By adjusting the flow rate adjusting valve, an arbitrary amount of the liquid refrigerant in the receiver is mixed with the gas refrigerant in the injection circuit so that it can be injected into the compressor.
Another feature of the present invention is an air conditioner having a refrigeration cycle in which a compressor, a heat source side heat exchanger, a first pressure reducing device, a receiver, a second pressure reducing device, and a use side heat exchanger are sequentially connected by piping, An injection circuit connected to an upper part of the receiver so as to take out the gas refrigerant in the receiver and connected to the compression chamber of the compressor, and provided in the middle of the pipe connecting the receiver and the second pressure reducing device. Heat exchange between a third pressure reducing device configured of an expansion valve capable of adjusting an opening degree, a refrigerant that has flowed out of the receiver and has been depressurized by the third pressure reducing device, and has been reduced in temperature, and a gas refrigerant guided to the injection circuit And a gas-liquid heat exchanger.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a system configuration of a heat pump cycle of an air conditioner according to an embodiment of the present invention, which includes a compressor 1, a four-way valve 2, a heat source side heat exchanger (outdoor heat exchanger) 3, a first expansion valve 4, and a receiver. 5, the blocking valve 6, the second expansion valves 7a and 7b, the use side heat exchangers (indoor heat exchangers) 8a and 8b, the blocking valve 9, and the compressor 1 are connected in order by piping. The injection circuit 107 is connected to the receiver 5 and a compression chamber in the compression process of the compressor 1. The injection circuit 107 is provided with an opening / closing valve (electromagnetic valve 11). Further, a liquid refrigerant extraction pipe 108 from a receiver is connected to the injection circuit 107, and the flow rate adjustment valve 10 is provided in the liquid refrigerant extraction pipe 108. Flow control valve 10 is desirably those of a valve which can close Me cutting. The receiver 5 has a function for accumulating excess refrigerant and a gas-liquid separation function for separating the gas refrigerant and the liquid refrigerant. The receiver function and the gas-liquid separation function may be provided with a receiver and a gas-liquid separator, The receiver should have both functions from the viewpoint of minimizing the installation space and cost.
[0009]
FIG. 1 shows the flow of refrigerant during cooling operation. The refrigerant that has become high-temperature and high-pressure gas in the compressor 1 is directed to the heat source side heat exchanger (outdoor heat exchanger) 3 by the four-way valve 2. In the heat source side heat exchanger 3, heat is radiated to the blown air (the blower system is not shown), and the refrigerant is condensed to be in a gas-liquid two-phase, saturated liquid or supercooled liquid refrigerant state. The determination of the state is controlled by the throttle amount of the first expansion valve 4. The refrigerant that has passed through the first expansion valve 4 is decompressed and enters a gas-liquid two-phase state and flows into the receiver 5. A saturated liquid refrigerant or a gas-liquid two-phase refrigerant is taken out from the receiver 5, and then passes through the blocking valve 6 to reach the second expansion valves 7a and 7b. The refrigerant becomes a gas-liquid two-phase refrigerant having a temperature lower than that of the room air at the second expansion valves 7a and 7b, and flows into the use side heat exchangers (indoor heat exchangers) 8a and 8b. In the use-side heat exchangers 8a and 8b, heat is absorbed from the blown room air (the blower system is not shown), and the gas refrigerant is returned to the compressor 1.
[0010]
The flow of the refrigerant during the heating operation is performed by switching the four-way valve 2 to flow the refrigerant in the reverse direction. The above description has been made in the case of a multi-unit in which two indoor units are connected to the outdoor unit 21, but either one of the indoor unit 22a or the indoor unit 22b is connected to the outdoor unit 21. The same applies to the single machine.
[0011]
The injection circuit 107 is connected to the upper part of the receiver 5 and takes out the gas refrigerant in the receiver. There are two types of injection methods depending on the state of the refrigerant taken out from the receiver 5. When the liquid or gas-liquid two-phase refrigerant is taken out and injected into the compressor 1, it becomes liquid injection, and the saturated gas refrigerant is taken out from the compressor 1. When it is injected, gas injection is performed.
[0012]
Hereinafter, it demonstrates as what performs gas injection. The driving force of gas injection is a pressure difference between the pressure of the compression chamber into which the compressor 1 is injected and the pressure of the receiver 5. Therefore, gas injection is performed when the pressure of the receiver 5 is higher than the pressure in the compression chamber of the compressor 1. The extraction pipe 108 is connected to the lower part of the receiver 5 and can take out the liquid refrigerant in the receiver. The gas refrigerant flowing through the injection circuit 107 and the liquid refrigerant flowing through the extraction pipe are mixed at a confluence 109 and injected into the compression process of the compressor 1 in a gas-liquid two-phase state.
[0013]
The mixing amount of the liquid refrigerant is adjusted by the flow rate adjusting valve 10, and is adjusted as variable from zero mixing amount to an arbitrary liquid refrigerant amount. However, the amount of liquid refrigerant mixed is small, for example, 0.95 or more in terms of dryness (= gas refrigerant mass flow rate / (gas refrigerant mass flow rate + liquid refrigerant mass flow rate)). Control of the amount of liquid refrigerant by the flow rate adjusting valve 10 may be performed by preparing and programming an opening setting table, for example, as used for controlling the first expansion valve and the second expansion valve. . As the parameters such as the cycle state used for opening setting, for example, two or more of any of the outside air temperature, the compressor temperature (corresponding to the compressor discharge temperature), the first expansion valve, and the second expansion valve are opened. Use. Further, if the on-off valve 11 of the injection circuit 107 is an expansion valve instead of an electromagnetic valve, finer control can be performed.
[0014]
The above air conditioners are used for each of the cooling operation and the heating operation, and even when the connection pipes 104 and 105 between the outdoor unit 21 and the indoor units 22a and 22b are long and the pressure loss is large. Regardless of the opening degree of the first expansion valve 4 and the second expansion valves 7a and 7b, it is possible to take out an arbitrary amount of liquid refrigerant from the receiver 5 and mix it with the injection gas refrigerant. Therefore, depending on the operation state of the cycle, a state from gas injection of 100% gas refrigerant to gas injection containing a small amount of liquid refrigerant can be created. Furthermore, if the amount of liquid refrigerant is increased, it is possible to substantially perform liquid injection. That is, it is preferable that the refrigerant injected into the compressor is variable from the gas refrigerant to the liquid refrigerant in accordance with the operation state of the cycle.
[0015]
FIG. 2 shows a system configuration of a heat pump cycle of an air conditioner as a reference example for the present invention . An ejector 12 is provided at the junction between the injection circuit 107 and the liquid refrigerant extraction pipe 108, and the liquid refrigerant in the receiver 5 is extracted by the pressure difference between the pressure when the injection gas refrigerant passes through the ejector and the pressure reduction in the receiver 5. To do. In this case, since the pressure in the ejector section is inversely proportional to the square of the flow rate of the injection gas refrigerant, it is possible to automatically extract the amount of liquid refrigerant corresponding to the flow rate of the injection gas refrigerant. To adjust the liquid refrigerant amount to be extracted, may be provided flow regulating valve in the middle of the liquid refrigerant extraction pipe 108, the capillary - may be or is provided the tubes can be more precisely control the flow rate of the liquid refrigerant.
[0016]
FIG. 3 shows a system configuration of a heat pump cycle of an air conditioner according to another embodiment of the present invention . In this example, the liquid refrigerant is not extracted from the receiver 5 and mixed into the injection gas refrigerant, but the injection gas refrigerant itself is cooled and a part thereof is liquefied. FIG. 3 shows a configuration in which liquid refrigerant can be mixed in gas injection during cooling operation. A third expansion valve 13 and a gas-liquid heat exchanger 14 are arranged between the receiver 5 and the blocking valve 6 from the receiver side, and the refrigerant flowing out of the receiver 5 is decompressed by the third expansion valve 13 so that the refrigerant temperature is the refrigerant in the receiver. It becomes lower than the temperature. This refrigerant and the injection gas refrigerant flowing through the injection circuit 107 are heat-exchanged by the gas-liquid heat exchanger 14 to liquefy a part of the injection gas refrigerant. The amount of refrigerant to be liquefied can be controlled by the refrigerant temperature that changes according to the amount of pressure reduction caused by the valve opening of the third expansion valve. If there is no pressure reduction at the third expansion valve, there is no refrigerant temperature difference between the injection gas refrigerant and the refrigerant after the receiver, so heat exchange is not performed and liquefaction does not occur. At this time, gas injection of 100% gas refrigerant is performed. Although not shown, in order to use it also during heating operation, a similar one may be provided upstream of the receiver 5 in the refrigerant flow direction shown in FIG. Alternatively, the receiver 5 is provided in the bridge circuit, the flow direction into and out of the receiver 5 is defined as one direction, and the same configuration (third expansion valve 13 and gas-liquid heat exchanger 14) is provided downstream of the receiver. Provide. The bridge circuit can determine the direction of the refrigerant flowing through the receiver 5 in one direction by combining, for example, four check valves.
[0017]
4 and 5 show a system configuration of a heat pump cycle of an air conditioner as another reference example for the present invention . In this example, the injection circuit 107 is provided with a gas refrigerant extraction port and a liquid refrigerant extraction port in the receiver 5 independently. FIG. 5 shows details of the injection circuit 107 in the receiver 5, and the end 19 of the injection circuit 107 reaches the lower part of the receiver 5 and is in the liquid refrigerant 30. A gas refrigerant outlet 16 is provided near the receiver upper end 32 of the injection circuit 107. As a result, the gas refrigerant 31 and the liquid refrigerant 30 can be taken out simultaneously by the injection circuit 107. The extraction amount of the liquid refrigerant 30 is set according to the inner diameter of the end pipe 15 of the injection circuit 107. Basically, the inner diameter of the end pipe 15 is preferably smaller than the inner diameter of the injection circuit 107. The extraction amount of the liquid refrigerant 30 determines the inner diameter of the end pipe 15 in accordance with the operating condition for which the effect of gas injection is to be maximized.
[0018]
1 to 5 is preferably located between the refrigerant pipe ports 18a and 18b and the receiver bottom face 33, and at least the refrigerant pipe from which the refrigerant flows out from the receiver. It is necessary for the liquid refrigerant 30 to be stably taken out that it is located between the mouth (18a or 18b depending on the refrigerant flow direction) and the receiver bottom surface 33. On the other hand, the extraction of the injection gas refrigerant 32 is provided on or near the upper end surface 32 of the receiver in order to prevent liquid refrigerant from entering.
[0019]
As described above, the extraction pipe for extracting the liquid refrigerant in the receiver is joined to the injection circuit, or the refrigerant in the injection circuit is partially cooled and liquefied, or the gas refrigerant extraction port and the liquid refrigerant extraction port that are independent on the injection circuit The gas refrigerant and the liquid refrigerant are simultaneously extracted by the injection circuit. By these, the refrigerant | coolant state injected into the compression process of a compressor is not the state of a 100% gas refrigerant, but mixes a small amount of liquid refrigerant (for example, dryness 0.95 or more), The cooling effect of the compressor by liquid refrigerant The coefficient of performance (cycle efficiency) at the time of gas injection can be improved. In addition, for each of the cooling operation and the heating operation, and even when the length of the connection pipe between the outdoor unit and the indoor unit is long and the pressure loss is large, a plurality of indoor units are connected to one outdoor unit. Even in the multi-type air conditioner, it is possible to take out an arbitrary amount of liquid refrigerant from the receiver and mix it with the injection gas refrigerant regardless of the opening degree of the first expansion valve and the second expansion valve. Therefore, depending on the operation state of the cycle, a state from gas injection of 100% gas refrigerant to gas injection containing a small amount of liquid refrigerant can be created. Further, if the amount of liquid refrigerant is increased, liquid injection can be performed. Furthermore, the above system configuration is applicable not only to the type of compressor but also to, for example, a scroll type and a rotary type, and can be applied regardless of the presence or absence of inverter control.
[0020]
In addition, if an injection circuit is installed, if the gas injection is performed, in the case of an inverter-driven compressor, if the capacity is the same, the operating frequency of the compressor can be reduced compared to the case without gas injection. Power consumption is reduced and energy saving operation (high coefficient of performance) is achieved. In the constant speed compressor, if the same stroke volume is used, the capacity can be increased, and if the same capacity is used, the stroke volume can be reduced. Therefore, energy saving and downsizing of the compressor operation can be achieved.
[0021]
The refrigerant state to be injected into the compressor is a gas-liquid two-phase state (for example, a dryness of 0.95 or more) containing a small amount of liquid refrigerant from a gas refrigerant, or a liquid injection containing a large amount of liquid refrigerant (for example, Therefore, it is possible to operate with a high coefficient of performance in a wide operating range by selecting the refrigerant state to be injected according to the conditions, and air conditioning. The operating efficiency of the machine can be improved and energy can be saved.
[0022]
In a compressor that operates at a constant speed, the stroke volume (theoretical discharge volume) of the compressor can be reduced by gas injection, and the load on the compressor is reduced accordingly. Therefore, the motor capacity can be reduced, and the compressor casing and the like can be reduced.
Further, the same effect can be obtained with R22, R410A, R32, R407C, natural refrigerants such as carbon dioxide and HC refrigerant, and the like.
[0023]
Furthermore, for each of the cooling operation and heating operation, and even when the length of the connecting pipe between the outdoor unit and the indoor unit is long and the pressure loss is large, a plurality of indoor units are connected to one outdoor unit. Even in the multi-type air conditioner, it is possible to take out an arbitrary amount of liquid refrigerant from the receiver and mix it with the injection gas refrigerant regardless of the opening degree of the first expansion valve and the second expansion valve. Therefore, by obtaining the cooling effect of the compressor by liquid refrigerant, the efficiency of the compressor can be improved by reducing the refrigerant temperature at the start of compression after gas injection and the discharge temperature of the compressor, and the discharge temperature of the compressor is lowered. Since the compressor motor cooling effect is increased and the motor efficiency is increased, the input of the compressor can be reduced. In addition, the temperature difference between the compressor and the ambient air is slightly small, but the amount of heat released from the compressor is also reduced. In addition, it is possible to create an optimum operating state adapted to the load, and it is possible to operate with a high coefficient of performance in a wide operating range, improve the operating efficiency of the air conditioner, and save energy. And, it is possible to reduce the amount of power consumption required to obtain the same cooling and heating capacity, and to reduce the amount of carbon dioxide emissions generated by the power production, and to make the air conditioner friendly to the global environment Can do.
[0024]
【The invention's effect】
As described above , according to the first aspect of the present invention, it is possible to take out an arbitrary amount of liquid refrigerant from the receiver and mix it with the injection gas refrigerant. Therefore, depending on the operation state of the cycle, a state from gas injection of 100% gas refrigerant to gas injection containing a small amount of liquid refrigerant can be created. Furthermore, if the amount of liquid refrigerant is increased, it is possible to substantially perform liquid injection.
Also, rather than the state of the compressor 100% gas refrigerant of the refrigerant state is injected in the compression process of, since it is mixed a small amount of liquid refrigerant becomes easy to obtain a cooling effect of the compressor by liquid refrigerant, the gas injection The coefficient of performance at the time (cycle efficiency) can be improved, and an air conditioner with high energy saving can be obtained.
According to the second aspect of the present invention, the same effect as that of the first aspect of the invention can be obtained.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of an air conditioner according to an embodiment.
FIG. 2 is a system configuration diagram of an air conditioner according to another embodiment.
FIG. 3 is a system configuration diagram of an air conditioner according to another embodiment.
FIG. 4 is a system configuration diagram of an air conditioner according to another embodiment.
FIG. 5 is a cross-sectional view showing details in the receiver in FIG. 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Four-way valve, 3 ... Heat source side heat exchanger (outdoor heat exchanger), 4 ... 1st expansion valve, 5 ... Receiver, 6 ... Stop valve, 7a, 7b ... 2nd expansion valve, 8a 8b ... use side heat exchanger (indoor heat exchanger), 9 ... blocking valve, 10 ... flow rate adjusting valve, 11 ... electromagnetic valve (open / close valve), 12 ... ejector, 13 ... third expansion valve, 14 ... gas liquid Heat exchanger, 15 ... Liquid refrigerant extraction pipe, 16 ... Gas refrigerant outlet, 17 ... Receiver part, 18a, 18b ... Refrigerant pipe opening, 19 ... Injection circuit end, 21 ... Outdoor unit, 22a, 22b ... Indoor unit, 30 DESCRIPTION OF SYMBOLS ... Liquid refrigerant, 31 ... Gas refrigerant, 32 ... Receiver upper end surface, 33 ... Receiver bottom surface, 101-106 ... Pipe, 107 ... Injection circuit, 108 ... Liquid refrigerant extraction pipe, 109 ... Merging part.

Claims (2)

In an air conditioner having a refrigeration cycle in which a compressor, a heat source side heat exchanger, a first pressure reducing device, a receiver, a second pressure reducing device, and a use side heat exchanger are connected by piping in sequence,
An injection circuit connected to the upper part of the receiver and connected to the compressor so as to take out the gas refrigerant in the receiver;
A liquid refrigerant extraction pipe provided to take out the liquid refrigerant in the receiver and connected to the injection circuit ;
A flow rate adjusting valve provided in the liquid refrigerant extraction pipe ,
An air conditioner characterized in that an arbitrary amount of liquid refrigerant in the receiver is mixed into the gas refrigerant of the injection circuit by adjusting the flow rate adjustment valve so that the refrigerant can be injected into the compressor . In an air conditioner having a refrigeration cycle in which a compressor, a heat source side heat exchanger, a first pressure reducing device, a receiver, a second pressure reducing device, and a use side heat exchanger are connected by piping in sequence,
An injection circuit connected to the upper part of the receiver to take out the gas refrigerant in the receiver and connected to the compression chamber of the compressor;
A third pressure reducing device constituted by an expansion valve provided in the middle of the pipe connecting the receiver and the second pressure reducing device, the opening degree of which can be adjusted;
A gas-liquid heat exchanger for exchanging heat between the refrigerant that has flowed out of the receiver and has been decompressed by the third decompression device and whose temperature has been reduced, and the gas refrigerant that has been guided to the injection circuit;
An air conditioner characterized in that it comprises.

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