JPH04236067A - Two-stage compression refrigerating cycle device - Google Patents

Abstract

PURPOSE:To increase the capacity and efficiency of the title device by a method wherein the refrigerant inlet ports for low-stage and high-stage of a refrigerant heat exchanger are connected to first and second throttle devices and the refrigerant outlet port for low-stage is connected between first and second non-return valves and a throttle device while a refrigerant outlet port for high-stage is connected to an intermediate point between a low-stage side compressing mechanism and a high-stage side compressing mechanism. CONSTITUTION:Upon heating operation, the refrigerant of a load side heat exchanger 4 is branched through first throttle devices 5 and a first non-return valve 11 and refrigerant for low-stage flows from a refrigerant/refrigerant heat exchanger 9 into a heat source side heat exchanger 7 through a fourth non-return valve 14 and a second throttle device 6 while refrigerant for high-stage flows to an intermediate point between a low-stage side compressing mechanism 1 and a high-stage side compressing mechanism 2 through an auxiliary throttle device 10 and the refrigerant/refrigerant heat exchanger 9. Upon cooling operation, the refrigerant of a heat source side heat exchanger 7 is branched through the second throttle device 6 and a second non-return valve 12 and refrigerant for low-stage flows from the refrigerant/ refrigerant heat exchanger 9 into the load side heat exchanger 4 through a third non-return value 13 and the first throttle devices 5 while the refrigerant for high-stage flows to an intermediate point between compressing mechanisms 1, 2 through the refrigerant/refrigerant heat exchanger 9. According to this method, the circulating amount of refregerant is increased and the capacity as well as the efficiently of the title device can be increased.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stage compression refrigeration cycle system for compressing circulating refrigerant in a refrigeration cycle using a low-stage compression mechanism and a high-stage compression mechanism.

0002

[Prior Art] In recent years, two-stage compression refrigeration cycle devices that compress circulating refrigerant in a refrigeration cycle using a low-stage compression mechanism and a high-stage compression mechanism have been applied to devices with multiple load-side heat exchangers. Therefore, it is required to be able to cope with large fluctuations in operating conditions.

Conventionally, when the ratio of evaporation pressure to condensation pressure (compression ratio) in the refrigeration cycle is large, such as in low-temperature refrigeration equipment or high-temperature heat pumps, further steps have been taken to prevent discharge temperature rise and improve compressor efficiency. A two-stage compression refrigeration cycle system in which two compressors are connected in series is widely used. In this case, the gas discharged from the low-stage compressor is cooled by direct or indirect heat exchange with high-pressure liquid refrigerant or intermediate-pressure two-phase refrigerant, and then sucked into the high-stage compressor, where it is heated to a high pressure. It is compressed, discharged and circulated within the cycle. By doing so, the temperature of the intake gas of the high-stage compressor is lowered and the discharge temperature thereof is prevented from rising. In addition, by appropriately setting the compression ratios of the low-stage and high-stage compressors, each stage of compressor can be operated under conditions with good efficiency, which improves overall refrigeration cycle efficiency. be.

[0004] Furthermore, this type of two-stage compression refrigeration cycle device is used exclusively for single-function applications such as low-temperature refrigeration equipment and high-temperature heat pumps, and is used for multiple purposes such as air-conditioning equipment, There are almost no examples of it being used in applications where conditions vary widely, and no specific configuration or operating method has been proposed for that purpose, but the inventors proposed a four-way valve in Japanese Patent Application No. 1-130810. The structure of a two-stage compression refrigeration cycle device and its operating method are disclosed.

Here, the structure of the invention of Japanese Patent Application No. 1-130810 will be explained with reference to FIG. 2. The low stage compression mechanism 21 and the high stage compression mechanism 22 are connected in series, and the four-way valve 2
3. A main refrigeration cycle is constructed by connecting the load side heat exchanger 24, the main expansion device 25, and the heat source side heat exchanger 26. Reference numeral 27 denotes a check valve group, and the refrigerant inlet 28c for the low stage and the refrigerant inlet 28a for the high stage via the sub-throttle device 29 of the refrigerant-to-refrigerant heat exchanger 28 for the low stage refrigerant and the high stage refrigerant are arranged in four directions. The load side heat exchanger 2 becomes a condenser by switching the valve 23
4 or the outlet of the heat source side heat exchanger 26. Further, the low stage refrigerant outlet 28d is connected to the main throttle device 25,
The high-stage refrigerant outlet 28b is connected to an intermediate confluence point between the low-stage compression mechanism 21 and the high-stage compression mechanism 22.

[0006] In such a configuration, the operating method will be explained. First, when the heating function is activated, the four-way valve 2
If the open circuit on the discharge side of No. 3 is placed on the inlet side of the load-side heat exchanger 24, the refrigerant pressurized to high pressure and discharged from the high-stage compression mechanism 22 passes through the four-way valve 23 and the load-side heat exchanger that becomes the condenser. Vessel 2
4. Via the check valve group 27, the refrigerant is branched into low stage refrigerant and high stage refrigerant. Here, the high-stage refrigerant is depressurized to an intermediate pressure by the sub-throttle device 29 to generate cold, and the low-stage refrigerant, which is heat-exchanged in the refrigerant-to-refrigerant heat exchanger 28, is cooled and its latent heat increases. The high stage refrigerant being replaced is heated and partially vaporized. The low stage refrigerant is reduced in pressure to a low pressure by the main expansion device 25, passes through the check valve group 27, the heat source side heat exchanger 26 serving as an evaporator, and the four-way valve 23, and is suctioned and compressed by the low stage side compression mechanism 21. The partially vaporized high-stage refrigerant is combined and sucked and compressed in the high-stage compression mechanism 22. Therefore, at intermediate pressure, the refrigerant discharged from the low-stage compression mechanism 21 is cooled by the partially vaporized high-stage refrigerant, preventing the discharge temperature of the high-stage compression mechanism 22 from increasing, and the low-stage compression mechanism The overall compressor efficiency of the compressor 21 and the high-stage compression mechanism 22 is improved. In addition, the refrigerant for the lower stage is used in the refrigerant-to-refrigerant heat exchanger 28.
The latent heat of evaporation increases in the heat source side heat exchanger 26, which serves as an evaporator, and the combined low-stage refrigerant and high-stage refrigerant circulate in the load-side heat exchanger 24, which serves as a condenser. This increases the amount of refrigerant circulation, achieving high capacity and efficiency.

Furthermore, when the cooling function is used, if the discharge side of the four-way valve 23 is opened on the inlet side of the heat source side heat exchanger 26,
Since the inlet sides of the low stage refrigerant and the high stage refrigerant are connected to the outlet side of the heat source side heat exchanger 26 by the check valve group 27, the refrigerant discharged from the high stage side compression mechanism 22 is connected to the four-way valve 23. The refrigerant is branched into a low stage refrigerant and a high stage refrigerant via a heat source side heat exchanger 26 serving as a condenser and a check valve group 27. Hereinafter, as in the case of the heating function, when the cooling function is used, not only does it prevent the discharge temperature from rising and improve compressor efficiency, but also the latent heat in the load-side heat exchanger 24, which becomes the evaporator, and the heat source, which becomes the condenser. The amount of refrigerant circulated in the side heat exchanger 26 increases, achieving high capacity and high efficiency.

[0008]

[Problems to be Solved by the Invention] However, in such a conventional two-stage compression refrigeration cycle device, the main throttling device 25 is used as a single unit to perform both heating and cooling functions, so a multi-type load-side heat exchange is required. In the case where the refrigerant 24 is provided, the connection piping in the refrigerant-to-refrigerant heat exchanger 28 at intermediate pressure must be devised.

The present invention solves the above-mentioned problems, and can be applied to devices that have both heating and cooling functions, such as multi-type air-conditioning equipment or air-conditioning/heating water heaters, and have a plurality of load-side heat exchangers. It is an object of the present invention to provide a two-stage compression refrigeration cycle device that can cope with large fluctuations in operating conditions.

0010

[Means for Solving the Problems] In order to achieve the above object, the present invention connects a low-stage compression mechanism and a high-stage compression mechanism in series, and includes a four-way valve, a load-side heat exchanger, and a first throttle device. , second
A main refrigeration cycle is constructed by connecting a throttling device, a heat source side heat exchanger, etc., and the refrigerant inlet for the low stage of the refrigerant-to-refrigerant heat exchanger and the refrigerant inlet for the high stage via the sub-throttle device are connected to the first check valve. The refrigerant outlet for the low stage is connected to the first throttle device and the second throttle device through the third check valve and the fourth check valve, respectively. It is connected between the stop valve and the first throttle device and between the second check valve and the second throttle device, and the high stage refrigerant outlet is connected between the low stage compression mechanism and the high stage compression mechanism. It is used as a means of solving problems.

[0011]

[Operation] According to the present invention, the refrigerant leaving the load-side heat exchanger, which functions as a condenser when in the heating function, is
The low-stage refrigerant is branched via the first throttle device and the first check valve, and the heat source side heat from the refrigerant-to-refrigerant heat exchanger passes through the fourth check valve and the second throttle device to the evaporator. The high-stage refrigerant flows out into the exchanger, and flows out into the middle of the low-stage compression mechanism and the high-stage compression mechanism via the sub-throttle device and the refrigerant-to-refrigerant heat exchanger. At this time, the second check valve and the third check valve prevent the low stage refrigerant from flowing out to the heat source side heat exchanger without passing through the refrigerant-to-refrigerant heat exchanger. In addition, in the case of the cooling function, the refrigerant that exits the heat source side heat exchanger, which serves as a condenser, is branched off via the second throttle device and the second check valve, and the refrigerant for the lower stage is transferred to the refrigerant-to-refrigerant heat exchanger. The high stage refrigerant flows through the third check valve and the first throttling device to the load side heat exchanger which becomes the evaporator, and the high stage refrigerant flows through the sub throttling device and the refrigerant-to-refrigerant heat exchanger to the low stage side. It flows out between the compression mechanism and the high-stage compression mechanism. At this time,
The first check valve and the fourth check valve prevent the low-stage refrigerant from flowing out to the load-side heat exchanger without passing through the refrigerant-to-refrigerant heat exchanger.

Therefore, by branching between the first throttle device and the first check valve, it becomes possible to connect a plurality of load-side heat exchangers and a plurality of corresponding first throttle devices, and a multi-type Even when an arbitrary load-side heat exchanger functions like an air-conditioning device or an air-conditioning/heating water supply device, it is possible to always configure a two-stage compression refrigeration cycle.

[0013]

[Embodiment] An embodiment of the present invention will be described below with reference to FIG.

As shown in the figure, the low-stage compression mechanism 1 connects the high-stage compression mechanism 2 in series, and includes a four-way valve 3, a plurality of load-side heat exchangers 4, a plurality of first expansion devices 5, and a first expansion device 5. 2 diaphragm device 6,
A main refrigeration cycle is configured by connecting the heat source side heat exchanger 7. Reference numeral 8 denotes an intermediate heat exchanger unit, in which the low stage refrigerant inlet 9c of the refrigerant-to-refrigerant heat exchanger 9 and the high stage refrigerant inlet 9a via the sub-throttle device 10 are connected to a first check valve 11 and a second check valve. They are connected to the first throttle device 5 and the second throttle device 6 through valves 12, respectively, and the low stage refrigerant outlet 9d is branched to the third throttle device.
The high-stage The refrigerant outlet 9b is connected to the middle of the low-stage compression mechanism 1 and the high-stage compression mechanism 2.

To explain the operating method in the above configuration, first, when the heating function is used, if the open circuit on the discharge side of the four-way valve 3 is placed on the inlet side of the load side heat exchanger 4, the flow from the high stage side compression mechanism 2 will be explained. The discharged refrigerant flows out of the four-way valve 3, the plurality of load-side heat exchangers 4 serving as condensers, and the plurality of first throttling devices 5, and passes through the first check valve 11 to become a low-stage refrigerant. Branched into high stage refrigerant. Here, the high-stage refrigerant is supplied to the sub-throttle device 10.
The pressure is reduced by the refrigerant to refrigerant heat exchanger 9 to generate cold.
The low stage refrigerant that undergoes heat exchange is cooled and its latent heat increases,
The high-stage refrigerant that is also heat-exchanged is heated, partially vaporizes, and flows out into the middle of the low-stage compression mechanism 1 and the high-stage compression mechanism 2. The refrigerant for the low stage is compressed on the low stage side via the refrigerant-to-refrigerant heat exchanger 9, the fourth check valve 14, the second expansion device 6, the heat source side heat exchanger 7 which serves as an evaporator, and the four-way valve 3. The refrigerant is suctioned and compressed in the mechanism 1, and the partially vaporized high-stage refrigerant is combined and suctioned and compressed in the high-stage compression mechanism 2. Therefore, the refrigerant discharged from the low-stage compression mechanism 1 is cooled by the partially vaporized high-stage refrigerant, and an increase in the discharge temperature of the high-stage compression mechanism 2 is prevented. The overall compressor efficiency of the stage-side compression mechanism 2 is improved. In addition, since the low-stage refrigerant is further subcooled in the refrigerant-to-refrigerant heat exchanger 9, the latent heat of evaporation in the heat source side heat exchanger 7, which serves as an evaporator, increases, and the heat exchanger on the load side, which serves as a condenser, increases. In the vessel 4, the combined low-stage refrigerant and high-stage refrigerant circulate, so the amount of refrigerant circulation increases, and high capacity and efficiency can be achieved. In addition, at this time, the second check valve 12 and the third
The check valve 13 prevents the low-stage refrigerant from flowing out to the heat source side heat exchanger 7 without passing through the refrigerant-to-refrigerant heat exchanger 9, and is configured to prevent the low-stage refrigerant from flowing out to the heat source side heat exchanger 7 without passing through the refrigerant-to-refrigerant heat exchanger 9. Even when only 4 is functioning, it is always possible to configure a two-stage compression refrigeration cycle.

Next, in the case of the cooling function, if the open circuit on the discharge side of the four-way valve 3 is placed on the inlet side of the heat source-side heat exchanger 7, the refrigerant discharged from the high-stage compression mechanism 2 will flow through the four-way valve 3. The refrigerant flows out of the heat source side heat exchanger 7 serving as a condenser, the second expansion device 6, and is branched into a low-stage refrigerant and a high-stage refrigerant via the second check valve 12. Here, the high-stage refrigerant is depressurized by the sub-throttle device 10 to generate cold, and the low-stage refrigerant, which is heat-exchanged in the refrigerant-to-refrigerant heat exchanger 9, is cooled and its latent heat increases, and is also heat-exchanged. The high-stage refrigerant is heated, partially vaporizes, and flows out between the low-stage compression mechanism 1 and the high-stage compression mechanism 2. The low-stage refrigerant is supplied to the refrigerant-to-refrigerant heat exchanger 9 and the third check valve 13.
is suctioned and compressed by the low-stage compression mechanism 1 via a plurality of first expansion devices 5, a plurality of load-side heat exchangers 4 serving as evaporators, and a four-way valve 3, and is partially sucked and compressed by the high-stage compression mechanism 2. The vaporized high-stage refrigerant is combined and sucked and compressed. For this reason, in the case of the cooling function, as in the case of the heating function, in addition to preventing a rise in discharge temperature and improving compressor efficiency, it is possible to reduce the amount of latent heat in the multiple load-side heat exchangers 4, which serve as evaporators, and the condenser. The amount of refrigerant circulated in the heat source side heat exchanger 7 increases, and high capacity and high efficiency are realized. Therefore, during the cooling function, the first check valve 11 and the fourth check valve 14 prevent the low-stage refrigerant from flowing out to the load-side heat exchanger 4 without passing through the refrigerant-to-refrigerant heat exchanger 9. This makes it possible to always configure a two-stage compression refrigeration cycle even when only an arbitrary load-side heat exchanger 4 among a plurality of load-side heat exchangers 4 functions.

The first throttle device 5 and the second throttle device 6 may be configured with electronic expansion valves that can be fully opened and fully closed, or may be configured with a combination of a capillary tube and a check valve (not shown). Modifications such as changes are included in the present invention. Furthermore, the refrigerant-to-refrigerant heat exchanger 9, the sub-throttle device 10, and the first to fourth check valves 11, 12, 13, and 14 can be combined into the intermediate heat exchanger unit 8 as one set, and two It can be applied to various applications of staged compression refrigeration cycle equipment.

[0018]

As is clear from the above embodiments, according to the present invention, the low-stage compression mechanism and the high-stage compression mechanism are connected in series, and the four-way valve, the load-side heat exchanger, and the first throttle device are connected in series. , a second throttling device, a heat source side heat exchanger, etc. are connected to form a main refrigeration cycle, and the refrigerant inlet for the low stage of the refrigerant-to-refrigerant heat exchanger and the refrigerant inlet for the high stage via the sub-throttle device are connected to the first refrigeration cycle. It is connected to the first throttle device and the second throttle device through the check valve and the second check valve, respectively, and the low stage refrigerant outlet is branched and connected through the third check valve and the fourth check valve, respectively. Connected between the first check valve and the first throttle device and between the second check valve and the second throttle device, and the high stage refrigerant outlet is connected between the low stage compression mechanism and the high stage compression mechanism. death,
Since the load-side heat exchanger and the first throttle device are configured with a plurality of load-side heat exchangers and a plurality of corresponding first throttle devices, any load-side heat exchanger can perform either heating or cooling functions. In this case, high capacity and high efficiency can be achieved by not only preventing discharge temperature rise and improving compressor efficiency, but also increasing the latent heat in the evaporator and the amount of refrigerant circulating in the condenser.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a two-stage compression refrigeration cycle device according to an embodiment of the present invention.

[Figure 2] Configuration diagram of a conventional two-stage compression refrigeration cycle device

[Explanation of symbols]

1 Low stage side compression mechanism 2 High stage side compression mechanism 3 Four-way valve 4 Load side heat exchanger 5 First squeezing device 6 Second diaphragm device 7 Heat source side heat exchanger 9 Refrigerant-to-refrigerant heat exchanger 10 Sub-diaphragm device 11 First check valve 12 Second check valve 13 Third check valve 14 Fourth check valve

Claims (2)

[Claims] Claim 1: A low-stage compression mechanism and a high-stage compression mechanism are connected in series, and include a four-way valve, a load-side heat exchanger, a first throttle device,
The second throttling device, the heat source side heat exchanger, etc. are connected to form the main refrigeration cycle, and the refrigerant inlet for the low stage of the refrigerant-to-refrigerant heat exchanger and the refrigerant inlet for the high stage via the sub-throttle device are connected to the first reverse. It is connected to the first throttle device and the second throttle device through the stop valve and the second check valve, respectively, and the low stage refrigerant outlet is branched to the third check valve and the fourth check valve.
The first check valve and the first throttle device are connected through the check valves, and the second check valve and the second throttle device are connected through the check valves, and the high stage refrigerant outlet is connected to the low stage compression mechanism and the high stage refrigerant outlet. A two-stage compression refrigeration cycle device connected to the middle of the side compression mechanism. 2. The two-stage compression refrigeration cycle device according to claim 1, wherein the load-side heat exchanger and the first expansion device are constituted by a plurality of load-side heat exchangers and a plurality of corresponding first expansion devices. .