JPH04257660A - Two stage compression refrigerating cycle device - Google Patents

Abstract

PURPOSE:To provide a two stage compression refrigerating cycle device which has both functions of heating and cooling such as a coldness storage/heat storage device or cooling/heating hot water supply device, and can be applied to a device for which heat accomodation is available by a plurality of heat exchangers. CONSTITUTION:Respective heat exchangers are connected with a high pressure gas pipe 7, low pressure gas pipe 8 and intermediate pressure liquid pipe 9 through switch valves and throttle device, and a gas/liquid separator 10 is provided on the intermediate pressure liquid pipe 9, and the peak is connected to the center between a low stage compressor 1 and a high stage compressor 2. Respective compressors are arranged in such a manner that series connection and parallel connection are available.

Description

[Detailed description of the invention]

0001

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

0002

[Prior Art] 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, it has been difficult to improve compressor efficiency and prevent a rise in discharge temperature. For this reason, two-stage compression refrigeration cycle equipment in which two single-stage compressors are installed in series is widely used. In this case, 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. In addition, cooling the discharge gas of the low-stage compressor by direct or indirect heat exchange with intermediate-pressure saturated or two-phase refrigerant reduces the temperature of the suction gas of the high-stage compressor and prevents the discharge temperature from rising. Overall, the refrigeration cycle efficiency is improved.

However, conventional two-stage compression refrigeration cycle equipment has been used exclusively for single-function applications such as low-temperature refrigeration equipment and high-temperature heat pumps, and has been used not only for ordinary air-conditioning equipment but also for cold storage heat-cooling equipment and air-conditioning/heating/hot-water supply. There have been no examples of devices being used for multiple purposes, and no specific configuration has been proposed for this purpose.

0004

[Problem to be solved by the invention] Due to its principle, a two-stage compression refrigeration cycle device is suitable for use with a large compression ratio, such as cold storage heat or hot water supply. It would be extremely useful to realize a new refrigeration cycle configuration.

The present invention provides a two-stage compression refrigeration cycle device that can be applied to devices that have both heating and cooling functions and can exchange heat between a plurality of heat exchangers, such as a cold storage heat/air conditioner or an air conditioner/heater hot water supply device. The purpose is to

[0006]

[Means for Solving the Problems] In order to achieve the above object, the two-stage compression refrigeration cycle device of the present invention has a first means in which a low-stage compressor and a high-stage compressor are connected in series, and the heat source side One end of the heat exchanger is branch-connected to a high-pressure gas pipe that discharges refrigerant from the high-stage compressor and a low-pressure gas pipe that takes refrigerant to the low-stage compressor through a switching valve, and the other end is connected through a throttling device. Connect one end of the multiple working side heat exchangers to the intermediate pressure liquid pipe, and install a switching valve between the high pressure gas pipe that serves as the refrigerant discharge for the high stage compressor and the low pressure gas pipe that serves as the refrigerant suction for the low stage compressor. The other end is connected to an intermediate pressure liquid pipe via a throttle device.

[0007] In addition, the second means is an intermediate pressure fluid, in which the other end of the heat source side heat exchanger is connected via a throttling device, and the other ends of the plurality of working side heat exchangers are connected via a throttling device. in the tube,
A gas-liquid separator is provided, and the top thereof is connected to piping that serves as the refrigerant discharge of the low-stage compressor and the refrigerant suction of the high-stage compressor.

Furthermore, a third means has a configuration in which the refrigerant discharge of the low-stage compressor is connected to the high-pressure gas pipe via a switching valve, and the refrigerant suction of the high-stage compressor is connected to the low-pressure gas pipe via the switching valve. It is something to do.

[0009]

[Operation] The two-stage compression refrigeration cycle of the present invention has the above-mentioned configuration, and by connecting any of the heat source side heat exchanger and the plurality of working side heat exchangers to a high pressure gas pipe or a low pressure gas pipe via a switching valve. , when the heat exchanger on the heat source side acts as a condenser and the heat exchanger on the working side acts as an evaporator, when the heat exchanger on the heat source side acts as an evaporator and the heat exchanger on the working side acts as a condenser, or when using an arbitrary function. When the side heat exchanger is used as a condenser and the other active side heat exchanger is used as an evaporator, a two-stage compression refrigeration cycle can be configured and highly efficient operation can be achieved.

In addition, a gas-liquid separator is installed in the intermediate pressure liquid pipe, and the top of the separator is connected to the pipes for the refrigerant discharge of the low stage compressor and the refrigerant suction of the high stage compressor, so that the discharge gas of the low stage compressor is can be cooled by direct heat exchange with an intermediate-pressure saturated or two-phase refrigerant, and can lower the suction gas temperature of the high-stage compressor and prevent its discharge temperature from rising. This improves efficiency.

Furthermore, the refrigerant discharge of the low-stage compressor is connected to the high-pressure gas pipe through the switching valve, and the refrigerant suction of the high-stage compressor is connected to the low-pressure gas pipe through the switching valve. In addition to connecting the compressor and high-stage compressor in series, it is also possible to connect each compressor in parallel to achieve high-capacity operation at a low compression ratio.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the two-stage compression refrigeration cycle device of the present invention, and the case where it is applied as a cold storage heat air conditioning device will be described. 1 is a low stage compressor, 2 is a high stage compressor, 3 is a heat source side heat exchanger, 4 and 5 are a plurality of working side heat exchangers, and low stage compressor 1 and high stage compressor 2 are connected to piping 6. are connected in series. The heat source side heat exchanger 3 shown here is an air heat exchanger installed outdoors, and the working side heat exchanger 4
is a water heat exchanger placed in an outdoor cold storage heat tank (not shown), and the working side heat exchanger 5 is an air heat exchanger placed indoors. One end of the heat source side heat exchanger 3 has switching valves 3-a and 3-b connected to a high-pressure gas pipe 7 for discharging refrigerant from the high-stage compressor 2 and a low-pressure gas pipe 8 for inhaling refrigerant to the low-stage compressor 1. The other end is connected to the intermediate pressure liquid pipe 9 via a throttle device 3-c. Multiple working side heat exchangers 4, 5
One end is a high-pressure gas pipe 7 that serves as a refrigerant discharge for the high-stage compressor 2, and a low-pressure gas pipe 8 that serves as a refrigerant suction for the low-stage compressor 1, respectively.
The other end is connected to the intermediate pressure liquid pipe 9 via the throttle device 4-c, 5-c. There is. In addition, in the intermediate pressure liquid pipe 9,
A gas-liquid separator 10 is provided, the top of which is connected to a pipe 6 for discharging refrigerant from the low-stage compressor 1 and for refrigerant intake for the high-stage compressor 2;
They are connected by piping 11. Furthermore, the refrigerant discharge of the low-stage compressor 1 is connected to the high-pressure gas pipe 7 via the switching valve 12-a, and the refrigerant suction of the high-stage compressor 2 is connected to the low-pressure gas pipe 8 via the switching valve 12-b. connected, and a switching valve 1 is installed in the pipe 6.
3-a, a switching valve 13-b is provided in the pipe 11.

[0014] In such a configuration, the operating method will be explained. When configuring a normal two-stage compression refrigeration cycle, the switching valves 12-a and 12-b are closed, and the switching valve 1 is closed.
3-a is opened. First, when the heat source side heat exchanger 3 is used as a condenser and the working side heat exchanger 4 is used as an evaporator, the switching valves 3-a and 4-b are opened, and the other switching valves are closed. The refrigerant sealed in the cycle is transferred to the low stage compressor 1→
Piping 6 → High stage compressor 2 → High pressure gas pipe 7 → Heat source side heat exchanger 3 → Throttle device 3-c → Intermediate pressure liquid pipe 9 → Throttle device 4-c →
It circulates in the order of the working side heat exchanger 4 → low pressure gas pipe 8 → low stage compressor 1, and while the heat source side heat exchanger 3 exhausts heat to the outside air, it becomes possible to store cold in the working side heat exchanger 4, and evaporate. Highly efficient operation is possible even at high compression ratios where the temperature is below the freezing point. Here, the switching valve 13- in the pipe 11
When b is opened, the saturated or two-phase refrigerant in the gas-liquid separator 10 is sucked, the discharge gas of the low-stage compressor 1 is cooled, and the suction gas temperature of the high-stage compressor 2 is lowered, causing its discharge temperature to rise. It is also possible to prevent this, and the refrigeration cycle efficiency is further improved.

Further, when the heat source side heat exchanger 3 is used as an evaporator and the working side heat exchanger 4 is used as a condenser, the switching valve 3
-b and 4-a are opened and the other switching valves are closed, the refrigerant sealed in the refrigeration cycle is transferred from the low stage compressor 1 to the piping 6.
→ High stage compressor 2 → High pressure gas pipe 7 → Working side heat exchanger 4 → Throttle device 4-c → Intermediate pressure liquid pipe 9 → Throttle device 3-c → Heat source side heat exchanger 3 → Low pressure gas pipe 8 → Low The air circulates in the order of the stage compressor 1, and while the heat exchanger 3 on the heat source side absorbs heat from the outside air, it is possible to store heat in the heat exchanger 4 on the working side, and in the case of a high compression ratio where the condensing temperature is high. It also allows for highly efficient operation. Here, the switching valve 13-b also in the pipe 11
When opened, the saturated or two-phase refrigerant in the gas-liquid separator 10 is sucked, the discharge gas of the low-stage compressor 1 is cooled, and the temperature of the suction gas of the high-stage compressor 2 is lowered, thereby suppressing the rise in its discharge temperature. This can also be prevented and further improves refrigeration cycle efficiency.

Further, when the working side heat exchanger 4 is used as a condenser and the working side heat exchanger 5 is used as an evaporator, the switching valve 4
When -a and 5-b are opened and the other switching valves are closed, the refrigerant sealed in the refrigeration cycle is transferred from the low stage compressor 1 to the piping 6.
→ High stage compressor 2 → High pressure gas pipe 7 → Working side heat exchanger 4 → Throttling device 4-c → Intermediate pressure liquid pipe 9 → Throttling device 5-c → Working side heat exchanger 5 → Low pressure gas pipe 8 → Low It is possible to cool the air in the working side heat exchanger 5 while absorbing cold heat from the working side heat exchanger 4 which circulates in the order of the stage compressor 1 and cools, and the working side heat exchanger 4 is used as an evaporator and a working side heat exchanger 5. When the side heat exchanger 5 is used as a condenser, when the switching valves 4-b and 5-a are opened and the other switching valves are closed, the heat stored on the working side is caused by the same refrigerant flow as described above. It becomes possible to perform heating with the working side heat exchanger 5 while absorbing thermal heat from the heat exchanger 4. In these cases, in this embodiment, when the switching valve 13-b in the pipe 11 is closed, the gas-liquid separator 10 acts as a reservoir for surplus refrigerant.

Furthermore, when the heat source side heat exchanger 3 is used as a condenser and the working side heat exchanger 5 is used as an evaporator, the switching valves 3-a and 5-b are opened and the other switching valves are closed. Then, while the heat source side heat exchanger 3 exhausts heat to the outside air, the working side heat exchanger 5 can perform cooling, and conversely, the heat source side heat exchanger 3
When operating the heat exchanger 5 as an evaporator and the heat exchanger 5 on the working side as a condenser, open the switching valves 3-b and 5-a and close the other switching valves. It becomes possible to perform heating with the working side heat exchanger 5 while absorbing heat from the air.

Here, when the cold storage heat is absorbed from the working side heat exchanger 4 and the working side heat exchanger 5 performs air conditioning, or when the heat is absorbed and exhausted by the heat source side heat exchanger 3 and the working side heat exchanger 5 performs air conditioning or heating. In this case, open the switching valves 12-a and 12-b and close the switching valve 13.
When -a and 13-b are closed, the refrigerant discharges of the low-stage compressor 1 and the high-stage compressor 2 are both connected to the high-pressure gas pipe 7, and the refrigerant intake of the low-stage compressor 1 and the high-stage compressor 2 is Since both are connected to the low-pressure gas pipe 8, the compressors 1 and 2 are connected in parallel, allowing high-capacity operation at a low compression ratio.

In this embodiment, a plurality of working side heat exchangers 4,
5 has been described as a water heat exchanger 4 disposed in a cold storage heat exchanger (not shown) and an air heat exchanger 5 installed indoors, but a plurality of air heat exchangers (not shown) may also be used. may be connected to form a multi-type, or if the water heat exchanger 4 has a single function of cold storage or heat storage, the switching valve 4-a attached to it,
4-b may be removed and the low pressure gas pipe 8 or high pressure gas pipe 7 may be directly connected. Further, the switching valves a and b attached to each heat exchanger 3, 4, and 5 may be valves whose opening degree can be controlled,
Switching valves 12-a, 12-b, 13-a for switching the low-stage compressor 1 and the high-stage compressor 2 between series connection and parallel connection
Of course, it may be constructed by a combination of a four-way valve and a check valve (not shown). Furthermore, for the piping connecting the indoor and outdoor areas, the high-pressure gas pipe 7, low-pressure gas pipe 8, and intermediate-pressure liquid pipe 9 may be extended as they are to form three pipes, or the high-pressure gas pipe 7, low-pressure gas pipe 8, and intermediate-pressure liquid pipe The pipe 9 is configured in the outdoor unit, and the working side heat exchanger 5 and the throttle device 5-c are configured in the indoor unit.
It is also possible to arrange two pipes by arranging only one pipe.

[0020]

As is clear from the above embodiments, according to the present invention, a low stage compressor and a high stage compressor are connected in series, and one end of the heat source side heat exchanger is connected to the refrigerant of the high stage compressor. The high-pressure gas pipe that serves as the discharge and the low-pressure gas pipe that serves as the refrigerant suction for the low-stage compressor are branched and connected via a switching valve, and the other end is connected to the intermediate pressure liquid pipe via a throttling device. One end of the heat exchanger is branch-connected to a high-pressure gas pipe that discharges refrigerant from the high-stage compressor and a low-pressure gas pipe that takes refrigerant to the low-stage compressor through a switching valve, and the other end is connected through a throttling device. A gas-liquid separator is installed in the intermediate pressure liquid pipe, and its top is connected to the pipe that serves as the refrigerant discharge of the low stage compressor and the refrigerant suction of the high stage compressor. The refrigerant discharge of the stage compressor is connected to the high-pressure gas pipe via a switching valve, and the refrigerant suction of the high-stage compressor is connected to the low-pressure gas pipe via the switching valve. By connecting any of the working side heat exchangers to a high-pressure gas pipe or a low-pressure gas pipe via a switching valve, a two-stage compression refrigeration cycle can be configured in any operation mode, allowing highly efficient operation. It is possible. In addition, a gas-liquid separator was installed in the intermediate-pressure liquid pipe, and the top of the separator was connected to the piping that serves as the refrigerant discharge of the low-stage compressor and the refrigerant suction of the high-stage compressor. It can be cooled by direct heat exchange with saturated or two-phase refrigerant, and can lower the intake gas temperature of the high-stage compressor and prevent its discharge temperature from rising, further improving refrigeration cycle efficiency. It is something to do. In addition, the refrigerant discharge of the low-stage compressor is connected to the high-pressure gas pipe via a switching valve, and the refrigerant suction of the high-stage compressor is connected to the low-pressure gas pipe via the switching valve. It is possible to provide a two-stage compression refrigeration cycle device that not only connects the compressor and high-stage compressor in series but also connects each compressor in parallel to enable high-capacity operation at a low compression ratio.

[Brief explanation of the drawing]

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

[Explanation of symbols]

1 Low stage compressor 2 High stage compressor 3 Heat source side heat exchanger 4, 5 Working side heat exchanger 7 High pressure gas pipe 8 Low pressure gas pipe 9 Intermediate pressure liquid pipe 10 Gas-liquid separator

Claims (3)

[Claims] Claim 1: A low stage compressor and a high stage compressor are connected in series,
One end of the heat exchanger on the heat source side is branch-connected via a switching valve to a high-pressure gas pipe that serves as a refrigerant discharge for the high-stage compressor and a low-pressure gas pipe that serves as a refrigerant intake for the low-stage compressor, and the other end is connected to a throttling device. Connect one end of the multiple working side heat exchangers with intermediate pressure liquid pipes through
The high-pressure gas pipe that discharges the refrigerant of the high-stage compressor and the low-pressure gas pipe that takes in the refrigerant of the low-stage compressor are branched and connected via a switching valve, and the other end is connected to the intermediate-pressure liquid pipe via a throttling device. Two-stage compression refrigeration cycle equipment. Claim 2: A low stage compressor and a high stage compressor are connected in series,
One end of the heat exchanger on the heat source side is branch-connected via a switching valve to a high-pressure gas pipe that serves as a refrigerant discharge for the high-stage compressor and a low-pressure gas pipe that serves as a refrigerant intake for the low-stage compressor, and the other end is connected to a throttling device. Connect one end of the multiple working side heat exchangers with intermediate pressure liquid pipes through
The high-pressure gas pipe that discharges the refrigerant of the high-stage compressor and the low-pressure gas pipe that takes in the refrigerant of the low-stage compressor are branched and connected via a switching valve, and the other end is connected to the intermediate-pressure liquid pipe via a throttling device. A two-stage compression refrigeration cycle device in which a gas-liquid separator is provided in the intermediate-pressure liquid pipe, and the top of the separator is connected to piping that serves as the refrigerant discharge of the low-stage compressor and the refrigerant suction of the high-stage compressor. Claim 3: A low stage compressor and a high stage compressor are connected in series,
One end of the heat exchanger on the heat source side is branch-connected via a switching valve to a high-pressure gas pipe that serves as a refrigerant discharge for the high-stage compressor and a low-pressure gas pipe that serves as a refrigerant intake for the low-stage compressor, and the other end is connected to a throttling device. Connect one end of the multiple working side heat exchangers with intermediate pressure liquid pipes through
The high-pressure gas pipe that discharges the refrigerant of the high-stage compressor and the low-pressure gas pipe that takes in the refrigerant of the low-stage compressor are branched and connected via a switching valve, and the other end is connected to the intermediate-pressure liquid pipe via a throttling device. A two-stage compression refrigeration cycle device in which the refrigerant discharge of the low-stage compressor is connected to a high-pressure gas pipe via a switching valve, and the refrigerant intake of the high-stage compressor is connected to a low-pressure gas pipe via a switching valve.