JPH04268165A - Two-stage compression refrigeration cycle equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 obtaining higher or lower temperatures, such as for air conditioning, hot water supply, or ultra-low temperature equipment.

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 necessary to prevent a rise in the discharge temperature of the compressor and improve compressor efficiency. In order to improve this, a two-stage compression device in which two conventional single-stage compressors are installed in series is 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 the high-pressure It is compressed and discharged. 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.

0003

[Problems to be Solved by the Invention] However, the above-mentioned conventional configurations are used exclusively for single-function applications such as low-temperature refrigeration equipment and high-temperature heat pumps, and are used for multi-purpose applications such as air-conditioning and hot water supply equipment. There were not many proposals for a specific structure. Therefore, when used in applications where operating conditions vary widely, there is a problem in that sufficient cycle efficiency cannot be obtained.

The present invention solves the above-mentioned conventional problems and can be applied to air-conditioning, heating, and hot water supply equipment, and is applicable to systems with widely different operating conditions, such as heating operation with a relatively low compression ratio and high-temperature hot water supply operation with a large compression ratio. It is an object of the present invention to provide a two-stage compression refrigeration cycle device that can always operate simultaneously with high cycle efficiency even in the case of high cycle efficiency.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a low stage compressor which is connected via piping to the discharge side of the heat exchanger on the heat source side and the intake side of the first heat exchanger on the load side. , an intermediate heat exchanger connected to the discharge side of the first load-side heat exchanger, and a first throttle device connected to the discharge side of the intermediate heat exchanger and the intake side of the heat source-side heat exchanger; a high-stage compressor connected to the discharge side of the intermediate heat exchanger; a second load-side heat exchanger connected to the discharge side of the high-stage compressor; a second throttle device connected to the discharge side, the outlet side of the second throttle device is connected to piping between the first throttle device and the heat source side heat exchanger, and the second load side heat exchanger The refrigerant in the pipe between the device and the second throttle device and the refrigerant in the pipe in the intermediate heat exchanger indirectly exchange heat, and the intermediate heat exchanger and the high-stage compressor are connected. Heat is exchanged indirectly between the piping and the outlet piping of the second load-side heat exchanger.

[0006]

[Function] In the above configuration, the heating operation is performed using the discharge gas of the low-stage compressor, and the refrigerant gas that remains without being liquefied is further compressed to a high pressure by the high-stage compressor, and the discharge gas increases the temperature. It performs high hot water supply operation, and simultaneously performs single-stage compression operation suitable for low compression ratios and two-stage compression operation suitable for high compression ratios, and the first load side heat exchanger has a Since all the refrigerant passes through, the heat transfer coefficient within the heat exchanger increases, and the piping connecting the intermediate heat exchanger and the high stage compressor and the outlet piping of the second load side heat exchanger are Since heat is exchanged indirectly, the refrigerant gas sucked into the high-stage compressor becomes close to saturated gas, and heat can be exchanged efficiently without causing abnormalities in the discharge temperature.

[0007]

Embodiment An embodiment of the present invention will be described below with reference to FIG. As shown in the figure, the low stage compressor 1
The discharge side of a heat source side heat exchanger 2 such as an outdoor unit and the intake side of a first load side heat exchanger 3 such as an indoor unit are connected by piping.
An intermediate heat exchanger 4 is connected to the discharge side of the first load side heat exchanger 3, and a first throttle device 5 is connected to the discharge side of the intermediate heat exchanger 4 and the intake side of the heat source side heat exchanger 2. . Further, a high-stage compressor 6 is connected to the discharge side of the intermediate heat exchanger 4, a second load-side heat exchanger 7 is connected to the discharge side of the high-stage compressor 6, and a second load-side heat exchanger 7 is connected to the discharge side of the high-stage compressor 6. A second throttle device 8 is connected to the discharge side of 7. Then, the outlet side of the second throttle device 8 is connected to join the pipe between the first throttle device 5 and the heat source side heat exchanger 2, and the second throttle device 8 is connected to the pipe between the second load side heat exchanger 7 and the second throttle device 8. The refrigerant in the pipes between them and the refrigerant in the pipes 9 in the intermediate heat exchanger 4 indirectly exchange heat.

In the above configuration, the refrigerant gas compressed and discharged by the low-stage compressor 1 contributes to heating in the first load-side heat exchanger 3, and a part of it liquefies and forms an intermediate gas-liquid two-phase state. It flows into the heat exchanger 4. Here, it is separated into liquid and gas, and the liquid component expands to a low pressure in the first expansion device 5 and flows into the heat source side heat exchanger 2, where it absorbs heat from the outside air and vaporizes itself, and is compressed on the low stage side. It is sucked into machine 1 again.

On the other hand, the gas component is sucked into the high-stage compressor 6, further compressed to a high pressure, becomes high temperature, contributes to hot water supply in the second load-side heat exchanger 7, and condenses itself. moreover,
However, since the temperature inside the intermediate heat exchanger 4 is a gas-liquid two-phase refrigerant with a relatively low pressure, the temperature is lower than that of the liquid refrigerant that has exited the second load-side heat exchanger 7. The temperature of the refrigerant liquid inside the tank further decreases and becomes supercooled. Conversely, the liquid refrigerant in the intermediate heat exchanger 4 is heated and partially vaporized, and the liquid refrigerant in the high-stage compressor 6 is heated.
is attracted to. On the other hand, the supercooled refrigerant that has exited the pipe 9 is expanded to a low pressure in the second expansion device 8, merges with the refrigerant that has exited the first expansion device 5, and flows into the heat source side heat exchanger 2.

As described above, in heating where the compression ratio is relatively low, only the low stage compressor 1 is operated with single stage compression, and in hot water supply where the compression ratio is high, the low stage compressor 1 and the high stage compressor 1 are operated. Since the compressor 6 is operated with two-stage compression, operation suitable for each stage is possible, and cycle efficiency is improved.

Furthermore, the refrigerant sucked into the high-stage compressor 6 is a saturated gas separated by the intermediate heat exchanger 4, and even if the refrigerant is compressed to high temperature and high pressure for hot water supply by the high-stage compressor 6, The discharge gas temperature does not become abnormally high.

Furthermore, the liquid refrigerant in the pipe 9 is transferred to the intermediate heat exchanger 4.
Since the heat source is supercooled, the enthalpy decreases, the amount of heat that can be exchanged by the heat source side heat exchanger 2 increases, and the cycle efficiency improves.

Furthermore, the refrigerant flowing through the first load-side heat exchanger 3 is not only a liquefied refrigerant that contributes to heating, but also a mixture of gaseous refrigerant, so the flow velocity in the pipes of the heat exchanger is high. Therefore, the heat transfer coefficient can be improved.

FIG. 2 shows another embodiment. In this embodiment, the same components as those shown in FIG. 1 described above are given the same reference numerals, and only the differences will be explained. That is, the pipe 10 connecting the intermediate heat exchanger 4 and the high-stage compressor 6 and the pipe 11 connecting the second load-side heat exchanger 7 and the pipe 9 are indirectly heat-exchanged by the auxiliary heat exchanger 12. It is.

With the above configuration, even when refrigerant liquid flows from the intermediate heat exchanger 4 into the pipe 10, heat is exchanged between the pipe 11 through which the high temperature refrigerant liquid flows and the auxiliary heat exchanger 12. This means that it can be completely vaporized and there is no need to worry about liquid compression.

In this embodiment, the first load-side heat exchanger 3 having a heating function and the second load-side heat exchanger 7 having a hot water supply function have been described, but the present invention is not limited to these. Instead, for example, both the first load-side heat exchanger 3 and the second load-side heat exchanger 7 may be configured to perform heating, or may be configured to contribute to hot water supply.

[0017]

Effects of the Invention As is clear from the above embodiments, the two-stage compression refrigeration cycle device of the present invention has a low-stage compression refrigeration cycle system which is connected by piping to the discharge side of the heat exchanger on the heat source side and the intake side of the first heat exchanger on the load side. a side compressor, an intermediate heat exchanger connected to the discharge side of the first load side heat exchanger, and a first intermediate heat exchanger connected to the discharge side of the intermediate heat exchanger and the intake side of the heat source side heat exchanger. a throttle device, a high-stage compressor connected to the discharge side of the intermediate heat exchanger, a second load-side heat exchanger connected to the discharge side of the high-stage compressor, and the second load side. a second throttle device connected to the discharge side of the heat exchanger, the outlet side of the second throttle device being connected to piping between the first throttle device and the heat source side heat exchanger, and the second load The refrigerant in the piping between the side heat exchanger and the second throttling device and the refrigerant in the piping in the intermediate heat exchanger indirectly exchange heat, and by adopting this configuration, it is suitable for low compression ratios. Single-stage compression operation and two-stage compression operation that prevents discharge temperature rise and are suitable for high compression ratios are possible, and the high efficiency of the heat exchanger allows for downsizing, eliminating concerns about liquid compression, etc., resulting in safe operation. Can be done.

[Brief explanation of the drawing]

[Fig. 1] System configuration diagram of a two-stage compression refrigeration cycle device in an embodiment of the present invention.

[Figure 2] System configuration diagram of a two-stage compression refrigeration cycle device in another embodiment

[Explanation of symbols]

1 Low stage compressor 2 Heat source side heat exchanger 3 First load side heat exchanger 4 Intermediate heat exchanger 5 First squeezing device 6　High stage side compressor 7 Second load side heat exchanger 8 Second squeezing device

Claims (2)

[Claims] Claim 1: A low-stage compressor connected to the discharge side of the heat source side heat exchanger and the intake side of the first load-side heat exchanger, and a low-stage compressor connected to the discharge side of the first load-side heat exchanger. a first throttle device connected to the discharge side of the intermediate heat exchanger and the intake side of the heat source side heat exchanger; and a high stage side connected to the discharge side of the intermediate heat exchanger. a compressor; a second load-side heat exchanger connected to the discharge side of the high-stage compressor;
a second throttle device connected to the discharge side of the second load side heat exchanger, and an outlet side of the second throttle device is connected to piping between the first throttle device and the heat source side heat exchanger. and a two-stage compression refrigeration cycle device in which the refrigerant in the pipes between the second load-side heat exchanger and the second expansion device and the refrigerant in the pipes in the intermediate heat exchanger indirectly exchange heat. 2. The two-stage compression refrigeration cycle device according to claim 1, wherein heat is exchanged indirectly between the pipe connecting the intermediate heat exchanger and the high-stage compressor and the outlet pipe of the second load-side heat exchanger. .