Cascade dehumidification and refrigeration system of environmental test chamber

Abstract

The utility model discloses a cascade dehumidification and refrigeration system of an environmental test chamber, which is provided with a first-stage system and a second-stage system which are connected in parallel, and refrigerants of the first-stage system and the second-stage system exchange heat at a first heat exchanger in the middle. The second-stage system comprises a second compressor, a second condenser, an oil separator and an evaporator which are sequentially connected with the first heat exchanger in series to form a circulation path, a refrigeration path and a dehumidification path which are arranged in parallel are arranged between the first heat exchanger and the evaporator, and the refrigeration path comprises a second refrigeration electromagnetic valve and a second refrigeration throttling device which are sequentially connected in series; the dehumidification circuit comprises a damp and hot refrigeration electromagnetic valve, a damp and hot refrigeration throttling device and a second heat exchanger which are sequentially connected in series. The dehumidification circuit is additionally arranged in the second-stage system and shares the same evaporator with the refrigeration circuit, a humid and hot evaporator does not need to be independently arranged in the first-stage system, the space of the first-stage system is saved, and during dehumidification, water vapor of air in the test box cannot be frosted or frozen on the surface of the evaporator after encountering the evaporator with the high temperature.

Description

Technical Field

[0001] The utility model relates to the technical field of environmental test devices, in particular to a cascade dehumidification and refrigeration system for an environmental test chamber. Background Art

[0002] With the improvement of the quality requirements for industrial products, it is required that the products produced should be subjected to simulation tests before being put on the market, and the tests should be able to completely and truly simulate the real situation of the products during use. An environmental test chamber is a test chamber that can simulate different temperature and humidity environmental conditions to test the performance of products. It is widely used in the adaptability tests of automobiles, ships, electrical engineering, electronic products and their components, as well as other materials during storage, transportation and use in a low-temperature environment.

[0003] In order to improve the cooling effect and quickly reach the target temperature and humidity test environment, an environmental test chamber usually adopts a cascade dehumidification and refrigeration system. Its first-stage system and second-stage system jointly refrigerate. The refrigerant of the first-stage system cools down the refrigerant of the second-stage system at the middle heat exchanger, and then the evaporator of the second-stage system cools down the air in the test chamber. In the existing cascade dehumidification and refrigeration system, R404A refrigerant is injected into the compressor of the first-stage system to provide humidity for the whole system, and R23 refrigerant is injected into the compressor of the second-stage system. However, the existing cascade dehumidification and refrigeration system has the following problems during dehumidification: (1) Due to the internal space limitation of the first-stage system of some equipment, a humid and hot evaporator cannot be added separately in the first-stage system, which affects the dehumidification effect; (2) When the second-stage system dehumidifies, the refrigerant in the evaporator is supercooled, which will cause the water vapor in the environmental test chamber to frost or freeze on the surface of the evaporator after encountering it, affecting the refrigeration effect of the environmental test chamber. Summary of the Utility Model

[0004] In view of the above-mentioned shortcomings of the existing cascade dehumidification and refrigeration system for an environmental test chamber, such as the first-stage system cannot add a humid and hot evaporator separately due to space limitation, and the evaporator in the second-stage system is prone to frosting or icing on the surface due to supercooling during dehumidification, etc., the applicant of the present utility model provides a cascade dehumidification and refrigeration system for an environmental test chamber with a reasonable structure. A dehumidification path is added in the second-stage system and shares the same evaporator with the refrigeration path. By adjusting the opening ratio of the solenoid valves on the dehumidification path or the refrigeration path, the environmental test chamber can reach the target humidity and target temperature. At the same time, a heat exchanger is added on the dehumidification path to increase the temperature of the refrigerant in the evaporator and avoid frosting or icing on the surface of the evaporator.

[0005] The technical solution adopted by the utility model and the achieved beneficial effects are as follows:

[0006] A cascade dehumidification and refrigeration system for an environmental test chamber, having a first-stage system and a second-stage system connected in parallel. The refrigerants of the first-stage system and the second-stage system exchange heat at a first heat exchanger in the middle. The first-stage system includes a first compressor, a first condenser, a first refrigeration solenoid valve, and a first refrigeration throttling device that are sequentially connected in series with the first heat exchanger to form a circulation path. The second-stage system includes a second compressor, a second condenser, an oil separator, and an evaporator that are sequentially connected in series with the first heat exchanger to form a circulation path. Between the first heat exchanger and the evaporator, there are a refrigeration path and a dehumidification path arranged in parallel. The refrigeration path includes a second refrigeration solenoid valve and a second refrigeration throttling device connected in series in sequence. The dehumidification path includes a humid heat refrigeration solenoid valve, a humid heat refrigeration throttling device, and a second heat exchanger connected in series in sequence. A cold bypass is connected in parallel between the first heat exchanger and the second compressor. The cold bypass includes a cold bypass solenoid valve and a cold bypass throttling device connected in series in sequence.

[0007] R404A refrigerant is injected into the first compressor of the first-stage system to provide humidity for the entire system. R23 refrigerant is injected into the second compressor of the second-stage system. The refrigerant of the first-stage system exchanges heat with the refrigerant of the second-stage system at the first heat exchanger. The refrigerant of the first-stage system transfers humidity to the refrigerant of the second-stage system. A dehumidification path is added in the second-stage system and shares the same evaporator with the refrigeration path. There is no need to separately set a humid heat evaporator in the first-stage system, saving space in the first-stage system. When dehumidifying, the refrigerant sequentially enters the humid heat refrigeration throttling device and the second heat exchanger, and after warming up in the second heat exchanger, it enters the evaporator. The water vapor in the air of the test chamber will not frost or ice on the surface of the relatively high-temperature evaporator.

[0008] As a further improvement of the above technical solution:

[0009] A first drying filter is also connected in series between the first condenser and the first refrigeration solenoid valve, for drying the low-temperature and high-pressure liquid refrigerant discharged from the first condenser.

[0010] A second drying filter is also connected in series between the first heat exchanger and the refrigeration path, dehumidification path, and cold bypass arranged in parallel, for drying the refrigerant discharged after heat exchange in the second heat exchanger in the second-stage system.

[0011] The first heat exchanger is a plate heat exchanger. The refrigerant of the second-stage system exchanges heat with the refrigerant of the first-stage system in the first heat exchanger. Since the temperature of the refrigerant of the second-stage system is higher than that of the refrigerant of the first-stage system, the refrigerant of the second-stage system releases heat and cools down, and the refrigerant of the first-stage system transfers humidity to the refrigerant of the second-stage system.

[0012] The two ends of the first compressor are connected in parallel with a first hot gas bypass solenoid valve. If the temperature of the first compressor is too low, opening the first hot gas bypass solenoid valve allows the gas generated after compression by the first compressor to directly return to the first compressor, thereby enabling the first compressor to achieve thermal equilibrium.

[0013] The two ends of the second compressor are connected in parallel with a second hot gas bypass solenoid valve. When refrigeration and dehumidification are not required and the test chamber is under temperature-controlled humid and hot conditions, only the cold bypass is opened. The refrigerant directly returns to the second compressor after passing through the cold bypass throttling device, enabling the second compressor to continue operating and cooling. Opening the second hot gas bypass solenoid valve allows the high-temperature and high-pressure gas generated after compression by the second compressor to directly return to the second compressor via the hot circuit solenoid valve, thereby heating the circuit pipeline of the second compressor for defrosting.

[0014] A separate circuit is connected between the oil separator and the second compressor. The separator separates the oil from the refrigerant, and the oil can flow back into the second compressor.

[0015] The first refrigeration throttling device, the second refrigeration throttling device, the cold bypass throttling device, and the humid and hot refrigeration throttling device are capillary tubes or expansion valves. When the refrigerant passes through the throttling device, it can first reduce its pressure and temperature, and then expand into a low-pressure and low-temperature liquid. Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of the present utility model.

[0017] In the figure: 1. First compressor; 2. First condenser; 3. First drying filter; 4. First refrigeration solenoid valve; 5. First refrigeration throttling device; 6. First heat exchanger; 7. First hot gas bypass solenoid valve; 8. Second compressor; 9. Second condenser; 10. Oil separator; 11. Second drying filter; 12. Second refrigeration solenoid valve; 13. Second refrigeration throttling device; 14. Cold bypass solenoid valve; 15. Cold bypass throttling device; 16. Humid and hot refrigeration solenoid valve; 17. Humid and hot refrigeration throttling device; 18. Second heat exchanger; 19. Evaporator; 20. Second hot gas bypass solenoid valve. Detailed Embodiments

[0018] The following will describe the detailed embodiments of the present utility model with reference to the drawings.

[0019] As Figure 1 shown, the cascade dehumidification and refrigeration system of the environmental test chamber of the present utility model has a first-stage system and a second-stage system connected in parallel. The refrigerants of the first-stage system and the second-stage system exchange heat at the middle first heat exchanger 6. In this embodiment, the first heat exchanger 6 is a plate heat exchanger.

[0020] The first-stage system includes a first compressor 1, a first condenser 2, a first dryer filter 3, a first refrigeration solenoid valve 4, and a first refrigeration throttling device 5 that are sequentially connected in series with the first heat exchanger 6 to form a circulation path. The first refrigeration throttling device 5 can be a capillary tube, an expansion valve, etc. A first hot gas bypass solenoid valve 7 is connected in parallel at both ends of the first compressor 1.

[0021] The second-stage system includes a second compressor 8, a second condenser 9, an oil separator 10, and an evaporator 19 that are sequentially connected in series with the first heat exchanger 6 to form a circulation path. There are a refrigeration path and a dehumidification path that are connected in parallel between the first heat exchanger 6 and the evaporator 19. The refrigeration path includes a second refrigeration solenoid valve 12 and a second refrigeration throttling device 13 that are sequentially connected in series. The dehumidification path includes a humid and hot refrigeration solenoid valve 16, a humid and hot refrigeration throttling device 17, and a second heat exchanger 18 that are sequentially connected in series. A cold bypass is connected in parallel between the first heat exchanger 6 and the second compressor 8. The cold bypass includes a cold bypass solenoid valve 14 and a cold bypass throttling device 15 that are sequentially connected in series. The second refrigeration throttling device 13, the cold bypass throttling device 15, and the humid and hot refrigeration throttling device 17 can be a capillary tube, an expansion valve, etc. A second hot gas bypass solenoid valve 20 is connected in parallel at both ends of the second compressor 8. A separate circuit is connected between the oil separator 10 and the second compressor 8.

[0022] In the system of the present utility model, except that the evaporator 19 is located inside an environmental test chamber (not shown in the figure), all other components are located outside the environmental test chamber.

[0023] The working principle of the system of the present utility model is as follows: The first-stage system is used to provide humidity for the entire system. The first-stage system uses R404A refrigerant as the heat exchange medium. After the first compressor 1 compresses the low-temperature and low-pressure R404A refrigerant, the discharged high-temperature and high-pressure gaseous refrigerant enters the first condenser 2 and is cooled and liquefied to form a low-temperature and high-pressure liquid refrigerant. Then, it passes through the first dryer filter 3 to remove water, and flows into the first refrigeration solenoid valve 4 and the first refrigeration throttling device 5 to form a low-temperature and low-pressure liquid refrigerant. The first refrigeration solenoid valve 4 can be controlled independently to adjust the passing amount of the refrigerant at the first refrigeration throttling device 5. The refrigerant of the first-stage system evaporates and absorbs heat in the first heat exchanger 6 to achieve refrigeration. Then, the refrigerant of the first-stage system enters the first compressor 1 again to achieve cyclic refrigeration. If the temperature of the first compressor 1 is too low, the first hot gas bypass solenoid valve 7 is opened, so that the gas generated after the first compressor 1 compresses directly returns to the first compressor 1 through the hot circuit solenoid valve 1, so that the first compressor 1 achieves thermal balance.

[0024] The secondary system uses R23 refrigerant as the heat exchange medium. After the second compressor 8 compresses the R23 refrigerant, the discharged high-temperature and high-pressure gaseous refrigerant enters the second condenser 9 and is cooled and liquefied to form a low-temperature and high-pressure liquid refrigerant, achieving refrigerant precooling. Then, it passes through the oil separator 10 to separate the oil in the refrigerant. The oil flows back into the second compressor 8, and the remaining refrigerant enters the first heat exchanger 6 to exchange heat with the refrigerant of the primary system. Since the temperature of the refrigerant in the secondary system is higher than that of the refrigerant in the primary system, the refrigerant in the secondary system releases heat and cools down, and the refrigerant in the primary system transfers moisture to the refrigerant in the secondary system. The refrigerant in the secondary system then enters the second dryer filter 11 to be dried and dewatered. By controlling the opening and closing of the second refrigeration solenoid valve 12 on the refrigeration circuit, the humid heat refrigeration solenoid valve 16 on the dehumidification circuit, and the cold bypass solenoid valve 14 on the cold bypass through the PID algorithm, the proportion of the refrigerant entering the three different lines can be controlled, and thus the flow rate of the refrigerant entering the evaporator 19 or the second compressor 8 can be controlled to meet the requirements of different degrees of cooling and dehumidification. After passing through the throttle valve device, the liquid refrigerant changes from low-temperature and high-pressure to low-temperature and low-pressure. The low-temperature and low-pressure liquid refrigerant exchanges heat with the air in the environmental test chamber in the evaporator 19 and vaporizes and absorbs heat, and then enters the second compressor 8 again to achieve cycle refrigeration, and the air in the environmental test chamber is cooled down.

[0025] When only refrigerating, the refrigeration circuit is opened, the dehumidification circuit and the cold bypass are closed, that is, the second refrigeration solenoid valve 12 is opened, the humid heat refrigeration solenoid valve 16 and the cold bypass solenoid valve 14 are closed. The low-temperature and high-pressure liquid refrigerant becomes a low-temperature and low-pressure liquid refrigerant after entering the second refrigeration throttling device 13, and then enters the evaporator 19.

[0026] When only dehumidifying, the dehumidification circuit is opened, the refrigeration circuit and the cold bypass are closed, that is, the humid heat refrigeration solenoid valve 16 is opened, the second refrigeration solenoid valve 12 and the cold bypass solenoid valve 14 are closed. The low-temperature and high-pressure liquid refrigerant becomes a low-temperature and low-pressure liquid refrigerant after entering the humid heat refrigeration throttling device 17, and then enters the second heat exchanger 18 to be heated through heat exchange and then enters the evaporator 19, so that the temperature of the evaporator 19 is higher than 0 °C, and the humidity of the air in the test chamber is relatively high. When the water vapor encounters the evaporator 19 with a higher temperature, it will not frost or freeze on its surface.

[0027] When refrigeration and dehumidification are not required and the test chamber is under temperature-controlled humid and hot conditions, the second refrigeration solenoid valve 12 and the humid and hot refrigeration solenoid valve 16 are closed, and the cold bypass solenoid valve 14 is opened. The low-temperature and high-pressure liquid refrigerant forms a low-temperature and low-pressure liquid refrigerant after passing through the cold bypass throttling device 15, and then directly returns to the second compressor 8, enabling the second compressor 8 to continue working and cooling. If the circuit pipeline of the second compressor 8 is frosted due to subcooling, the second hot gas bypass solenoid valve 20 is opened, so that the high-temperature and high-pressure gas generated after compression by the second compressor 8 returns to the second compressor 8 again, heating the circuit pipeline of the second compressor 8 for defrosting.

[0028] When the system of the present utility model is operating, the staff can set the target temperature and target humidity through the touch screen on the environmental test chamber, and the PLC automatically judges and controls the output power of refrigeration or heating or dehumidification or humidification. When refrigeration output is required, the first compressor 1 and the first refrigeration solenoid valve 4 are first opened, and after an interval of 90 s, the second compressor 8 and the humid and hot refrigeration solenoid valve 16 are opened. The opening and closing ratios of the cold bypass solenoid valve 14 and the humid and hot refrigeration solenoid valve 16 are controlled according to the required refrigeration output, so as to achieve the temperature constancy under the temperature-controlled humid and hot conditions of the test chamber; when dehumidification output is required, the first compressor 1 and the first refrigeration solenoid valve 4 are first opened, and after an interval of 90 s, the second compressor 8 and the humid and hot refrigeration solenoid valve 16 are opened. The opening and closing ratios of the cold bypass solenoid valve 14 and the humid and hot refrigeration solenoid valve 16 are controlled according to the required dehumidification output, so as to achieve the temperature constancy under the temperature-controlled humid and hot conditions; when there are both refrigeration and dehumidification outputs, the output with the larger opening and closing ratio in the humid and hot refrigeration solenoid valve 16 is followed.

[0029] The above description is an explanation of the present utility model, not a limitation of the utility model. Without departing from the spirit of the present utility model, the present utility model can be modified in any form.

Claims

1. A cascade dehumidification and refrigeration system for an environmental test chamber, comprising a first-stage system and a second-stage system connected in parallel, wherein the refrigerants of the first-stage system and the second-stage system exchange heat at a first heat exchanger (6) in the middle, wherein the first-stage system comprises a first compressor (1), a first condenser (2), a first refrigeration solenoid valve (4) and a first refrigeration throttling device (5) which are sequentially connected in series with the first heat exchanger (6) to form a circulation path, and the second-stage system comprises a second compressor (8), a second condenser (9), an oil separator (10) and an evaporator (19) which are sequentially connected in series with the first heat exchanger (6) to form a circulation path, and wherein: A refrigeration circuit and a dehumidification circuit are arranged in parallel between the first heat exchanger (6) and the evaporator (19), the refrigeration circuit comprising a second refrigeration solenoid valve (12) and a second refrigeration throttling device (13) connected in series in sequence, the dehumidification circuit comprising a wet heat refrigeration solenoid valve (16), a wet heat refrigeration throttling device (17) and a second heat exchanger (18) connected in series in sequence, and a cold bypass is connected in parallel between the first heat exchanger (6) and the second compressor (8), the cold bypass comprising a cold bypass solenoid valve (14) and a cold bypass throttling device (15) connected in series in sequence.

2. The cascade dehumidification and refrigeration system of the environmental test chamber according to claim 1, characterized in that: A first drying filter (3) is also connected in series between the first condenser (2) and the first refrigeration solenoid valve (4).

3. The cascade dehumidification and refrigeration system of the environmental test chamber according to claim 1, characterized in that: A second drying filter (11) is also connected in series between the first heat exchanger (6) and the refrigeration circuit, dehumidification circuit and cold bypass circuit arranged in parallel.

4. The cascade dehumidification and refrigeration system of the environmental test chamber according to claim 1, characterized in that: The first heat exchanger (6) is a plate heat exchanger.

5. The cascade dehumidification and refrigeration system of the environmental test chamber according to claim 1, characterized in that: The first hot gas bypass solenoid valve (7) is connected in parallel at both ends of the first compressor (1).

6. The cascade dehumidification and refrigeration system of the environmental test chamber according to claim 1, characterized in that: The second hot gas bypass solenoid valve (20) is connected in parallel at both ends of the second compressor (8).

7. The cascade dehumidification and refrigeration system of the environmental test chamber according to claim 1, characterized in that: A separate circuit is connected between the oil separator (10) and the second compressor (8).

8. The cascade dehumidification and refrigeration system of the environmental test chamber according to claim 1, characterized in that: The first refrigeration throttling device (5), the second refrigeration throttling device (13), the cold bypass throttling device (15) and the wet heat refrigeration throttling device (17) are capillary tubes or expansion valves.

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