Cryogenic high-low temperature box refrigerating system adopting hot gas bypass

Abstract

The invention relates to a cryogenic high-low temperature box refrigerating system adopting hot gas bypass, which is characterized in that a double-channel intermediate cooling plate is provided with a plurality of channels, so that hot gas bypass gas of a low-temperature-stage compressor enters the double-channel intermediate cooling plate through a low-temperature-stage hot gas bypass passage; the pressure of the hot gas bypass gas can be adjusted under the action of the low-temperature stage hot gas bypass passage, and the temperature of the hot gas bypass gas is reduced in the double-channel intermediate cooling plate. Due to the arrangement of the double-channel intermediate cooling plate, the problems of pressure fluctuation and frosting of a low-temperature compressor cannot be generated when hot gas bypass gas passing through the double-channel intermediate cooling plate is converged with gas from a refrigeration evaporator; and the temperature change and the pressure change of the return air caused when the converged air returns to the low-temperature-stage compressor again are extremely small, so that the stability of a low-temperature-stage system is maintained.

Description

Technical Field

[0001] The present application relates to the technical field of high and low temperature boxes, and in particular to a deep cold high and low temperature box refrigeration system using hot gas bypass. Background Art

[0002] With the development of science and technology, the requirements for the performance and reliability of various automotive parts and electronic products are getting higher and higher. In order to speed up the research and development of related products, a large number of environmental performance tests are required. Therefore, there is an increasing demand for high and low temperature and humidity test chambers that can perform high temperature tests, low temperature tests, high and low temperature tests, and humidity and heat alternation tests.

[0003] High and low temperature environment boxes need to achieve a very fast speed in the cooling process, and maintain a stable box temperature when reaching the set temperature, such as -70℃. Therefore, the refrigeration capacity requirements in the two processes are very different. When selecting and designing, the maximum capacity requirement must be followed. Therefore, when maintaining the box temperature, it is necessary to use refrigeration energy regulation methods to meet actual use requirements, such as compressor frequency conversion, compressor parallel connection, hot gas bypass, etc. Among them, the hot gas bypass method has a relatively low cost of use, so it is more common.

[0004] Ordinary hot gas bypass generally passes through the exhaust of the compressor and returns directly to the compressor suction port after a certain amount of throttling. Therefore, it is easy to cause fluctuations in suction pressure and temperature. In particular, fluctuations in suction temperature can easily cause the exhaust temperature to be too high. When using hot gas bypass, it is also necessary to design liquid spray cooling to deal with the high exhaust temperature.

[0005] The existing hot gas bypass design easily causes the compressor suction pressure to fluctuate, causing the evaporation temperature of the evaporator to fluctuate, and finally the cabinet temperature fluctuation also increases. In addition, the increase in exhaust temperature triggers liquid spray cooling, and the amount of liquid spray cooling is very difficult to control, which can easily cause frost on the compressor and affect the service life of the compressor. Summary of the invention

[0006] Based on this, it is necessary to provide a deep-cold high and low temperature box refrigeration system with hot gas bypass, in view of the problem that the existing hot gas bypass design easily causes the compressor suction pressure to fluctuate up and down, causing the evaporation temperature of the evaporator to fluctuate, and finally the box temperature fluctuation also increases. In addition, the rise in exhaust temperature triggers liquid spray cooling, and the amount of liquid spray cooling is very difficult to control, which easily causes frost on the compressor and affects the service life of the compressor.

[0007] The present application provides a cryogenic high and low temperature box refrigeration system using hot gas bypass, comprising:

[0008] A high-temperature refrigeration circuit, wherein the high-temperature refrigeration assembly includes a high-temperature compressor, a high-temperature oil separator, a high-temperature condenser, a high-temperature filter, a dual-channel intercooler and a high-temperature gas-liquid separator connected in sequence;

[0009] A high-temperature hot gas bypass passage, wherein the high-temperature hot gas bypass passage is disposed between the high-temperature oil separator and the high-temperature gas-liquid separator, and the outlet of the high-temperature oil separator is connected to the inlet of the high-temperature gas-liquid separator through the high-temperature hot gas bypass passage;

[0010] a first high-temperature-stage liquid separation passage, wherein the first high-temperature-stage liquid separation passage is disposed between the high-temperature-stage filter and the dual-channel intercooler, and the outlet of the high-temperature-stage filter is connected to the high-temperature-stage inlet of the dual-channel intercooler through the first high-temperature-stage liquid separation passage;

[0011] A low-temperature refrigeration circuit, the low-temperature refrigeration circuit comprising a low-temperature compressor, a low-temperature oil separator, a precooling heat exchanger, a dual-channel intercooler, a refrigeration evaporator and a low-temperature gas-liquid separator connected in sequence;

[0012] A low-temperature hot gas bypass passage, wherein the first hot gas bypass passage comprises a low-temperature compressor, a low-temperature oil separator, a dual-channel intercooler, a refrigeration evaporator and a low-temperature gas-liquid separator connected in sequence;

[0013] The first low-temperature liquid separation passage comprises a precooling heat exchanger, a dual-channel intercooler, a refrigeration evaporator and a low-temperature gas-liquid separator which are connected in sequence.

[0014] The present application relates to a cryogenic high and low temperature box refrigeration system using hot gas bypass, in which a dual-channel intermediate cooling plate is arranged as a plurality of channels so that the hot gas bypass gas of the low temperature compressor enters the dual-channel intermediate cooling plate through the low temperature hot gas bypass passage, and the pressure of the hot gas bypass gas can be adjusted under the action of the low temperature hot gas bypass passage, and the temperature of the hot gas bypass gas is lowered in the dual-channel intermediate cooling plate, so that the hot gas bypass gas after passing through the dual-channel intermediate cooling plate will not generate pressure fluctuation and frosting of the low temperature compressor when it merges with the gas coming out of the refrigeration evaporator, and due to the arrangement of the low temperature hot gas bypass circuit, the temperature change and pressure change of the return gas caused when the merged gas returns to the low temperature compressor are extremely small, so as to maintain the stability of the low temperature system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic structural diagram of a cryogenic high and low temperature box refrigeration system using hot gas bypass is provided in one embodiment of the present application.

[0016] Figure 2A schematic structural diagram of a high temperature stage system of a cryogenic high and low temperature box refrigeration system using hot gas bypass is provided in one embodiment of the present application.

[0017] Figure 3 A high-temperature hot gas bypass gas circuit of a cryogenic high and low temperature box refrigeration system using hot gas bypass is provided in one embodiment of the present application.

[0018] Figure 4 A high-temperature main refrigeration circuit of a cryogenic high-low temperature box refrigeration system using hot gas bypass is provided in one embodiment of the present application.

[0019] Figure 5 A liquid spray cooling circuit of a cryogenic high and low temperature box refrigeration system using hot gas bypass is provided in one embodiment of the present application.

[0020] Figure 6 A schematic structural diagram of a low temperature stage system of a cryogenic high and low temperature box refrigeration system using hot gas bypass is provided in one embodiment of the present application.

[0021] Figure 7 A low temperature hot gas bypass circuit of a cryogenic high and low temperature box refrigeration system using hot gas bypass is provided in one embodiment of the present application.

[0022] Figure 8 A low-temperature main refrigeration circuit of a cryogenic high and low temperature box refrigeration system using hot gas bypass is provided in one embodiment of the present application.

[0023] Fig. 9 A second low temperature stage liquid separation passage circuit of a cryogenic high and low temperature box refrigeration system using hot gas bypass is provided in one embodiment of the present application.

[0024] Fig.10 A schematic structural diagram of a dual-channel intercooler of a cryogenic high and low temperature box refrigeration system using hot gas bypass provided in one embodiment of the present application.

[0025] Reference numerals:

[0026] 100. High temperature refrigeration circuit; 101. High temperature compressor; 102. High temperature oil separator;

[0027] 103. High temperature condenser; 104. High temperature filter; 105. Dual-channel intercooler;

[0028] 105a, high temperature channel; 105b, low temperature channel; 105c, hot gas bypass channel;

[0029] 105d, first inlet; 105e, second inlet; 106, high temperature gas-liquid separator;

[0030] 107. High temperature level liquid spray cooling regulating valve; 108. High temperature level low pressure switch;

[0031] 109. High temperature and high pressure switch; 110. Sight glass;

[0032] 200. High temperature hot gas bypass passage; 201. High temperature hot gas bypass solenoid valve;

[0033] 202. High temperature hot gas bypass regulating valve;

[0034] 300, first high temperature stage liquid separation passage; 301, high temperature stage main solenoid valve;

[0035] 302, high temperature thermal expansion valve;

[0036] 400. Low temperature refrigeration circuit; 401. Low temperature compressor; 402. Low temperature oil separator;

[0037] 403. Precooling heat exchanger; 404. Refrigeration evaporator; 405. Low-temperature gas-liquid separator;

[0038] 406. Low-temperature low-pressure switch; 407. Low-temperature high-pressure switch;

[0039] 500, low temperature hot gas bypass passage; 501, second passage; 502, low temperature hot gas bypass solenoid valve;

[0040] 503. Low temperature hot gas bypass regulating valve; 504. Bypass pressure sensor;

[0041] 600, first low temperature level liquid separation passage; 601, low temperature level high pressure pressure sensor;

[0042] 602, low temperature filter; 603, low temperature refrigeration solenoid valve; 604, low temperature thermal expansion valve; 700, second low temperature liquid separation passage; 701, pressure relief solenoid valve; 702, expansion tank. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0044] The present application provides a cryogenic high and low temperature box refrigeration system using hot gas bypass.

[0045] like Figures 1 to 9As shown, in one embodiment of the present application, the deep-freeze high and low temperature box refrigeration system using hot gas bypass includes a high-temperature stage refrigeration circuit 100, a high-temperature stage hot gas bypass passage 200, a first high-temperature stage liquid separation passage 300, a low-temperature stage refrigeration circuit 400, a low-temperature stage hot gas bypass passage 500 and a first low-temperature stage liquid separation passage 600.

[0046] The high temperature refrigeration circuit 100 includes a high temperature compressor 101, a high temperature oil separator 102, a high temperature condenser 103, a high temperature filter 104, a dual-channel intercooler 105 and a high temperature gas-liquid separator 106 which are connected in sequence. The high temperature hot gas bypass passage 200 is arranged between the high temperature oil separator 102 and the high temperature gas-liquid separator 106, and the outlet of the high temperature oil separator 102 is connected to the inlet of the high temperature gas-liquid separator 106 through the high temperature hot gas bypass passage 200. The first high temperature liquid separation passage 300 is arranged between the high temperature filter 104 and the dual-channel intercooler 105, and the outlet of the high temperature filter 104 is connected to the high temperature inlet of the dual-channel intercooler 105 through the first high temperature liquid separation passage 300.

[0047] The low-temperature refrigeration circuit 400 includes a low-temperature compressor 401, a low-temperature oil separator 402, a precooling heat exchanger 403, a dual-channel intercooler 105, a refrigeration evaporator 404, and a low-temperature gas-liquid separator 405 connected in sequence. The low-temperature hot gas bypass passage 500 includes a low-temperature compressor 401, a low-temperature oil separator 402, a dual-channel intercooler 105, a refrigeration evaporator 404, and a low-temperature gas-liquid separator 405 connected in sequence. The first low-temperature liquid separation passage 600 includes a precooling heat exchanger 403, a dual-channel intercooler 105, a refrigeration evaporator 404, and a low-temperature gas-liquid separator 405 connected in sequence.

[0048] Specifically, the cascade system of the high and low temperature boxes includes a high temperature stage system and a low temperature stage system, wherein the high temperature stage system includes a high temperature stage refrigeration circuit 100, a high temperature stage hot gas bypass passage 200 and a first high temperature stage liquid separation passage 300, and the low temperature stage system includes a low temperature stage refrigeration circuit 400, a low temperature stage hot gas bypass passage 500, a first low temperature stage liquid separation passage 600 and a second low temperature stage liquid separation passage 700.

[0049] In the actual experiment, the refrigerant used in the low-temperature system and the refrigerant used in the high-temperature system are two different refrigerants. When the high and low temperature boxes are working, the two refrigerants run counterclockwise with the low-temperature compressor 401 / high-temperature compressor 101 as the starting point.

[0050] In this embodiment, the dual-channel intercooler 105 is set as multiple channels, so that the hot gas bypass gas of the low-temperature compressor 401 enters the dual-channel intercooler 105 through the low-temperature hot gas bypass passage 500. Under the action of the low-temperature hot gas bypass passage 500, the pressure of the hot gas bypass gas can be adjusted, and the temperature of the hot gas bypass gas is reduced in the dual-channel intercooler 105, so that the hot gas bypass gas after passing through the dual-channel intercooler 105 will not cause pressure fluctuations and frosting of the low-temperature compressor when it merges with the gas coming out of the refrigeration evaporator 404. Due to the setting of the low-temperature hot gas bypass circuit, the temperature change and pressure change of the return gas caused by the merged gas returning to the low-temperature compressor 401 are extremely small, so as to maintain the stability of the low-temperature system.

[0051] like Figure 3 As shown, in one embodiment of the present application, the high-temperature hot gas bypass passage 200 includes a high-temperature hot gas bypass solenoid valve 201 and a high-temperature hot gas bypass regulating valve 202, the inlet of the high-temperature hot gas bypass solenoid valve 201 is connected to the outlet of the high-temperature oil separator 102, the outlet of the high-temperature hot gas bypass solenoid valve 201 is connected to the inlet of the high-temperature hot gas bypass regulating valve 202, and the outlet of the high-temperature hot gas bypass regulating valve 202 is connected to the inlet of the high-temperature gas-liquid separator 106.

[0052] In this embodiment, the gas in the high-temperature hot gas bypass passage 200 is divided into two paths after coming out of the outlet of the high-temperature oil separator 102. One path passes through the high-temperature hot gas bypass solenoid valve 201 and the high-temperature hot gas bypass regulating valve 202 to reach the high-temperature gas-liquid separator 106, and after being processed in the high-temperature gas-liquid separator 106, it finally re-enters the interior of the high-temperature compressor 101 through the inlet of the high-temperature compressor 101.

[0053] During the entire flow process of the high-temperature stage hot gas bypass, the flow is adjusted by adjusting the opening degree of the high-temperature stage hot gas bypass regulating valve 202. The greater the opening degree of the high-temperature stage hot gas bypass regulating valve 202, the greater the flow of the high-temperature stage hot gas bypass, and the smaller the opening degree of the high-temperature stage hot gas bypass regulating valve 202, the smaller the flow of the high-temperature stage hot gas bypass.

[0054] like Figure 4 As shown, in one embodiment of the present application, the first high-temperature stage liquid separation passage 300 includes a high-temperature stage main solenoid valve 301 and a high-temperature stage thermal expansion valve 302, the inlet of the high-temperature stage main solenoid valve 301 is connected to the outlet of the high-temperature stage filter 104, the outlet of the high-temperature stage main solenoid valve 301 is connected to the inlet of the high-temperature stage thermal expansion valve 302, and the outlet of the high-temperature stage thermal expansion valve 302 is connected to the high-temperature stage inlet of the dual-channel intercooler 105.

[0055] Specifically, the high temperature stage condenser 103 is provided with a cooling water inlet and a cooling water outlet for exchanging with the outside.

[0056] In this embodiment, when there is too much hot gas bypass or the time is too long, the intake temperature will rise, and the other path out of the outlet of the high-temperature oil separator 102 will enter the high-temperature condenser 103, and the gas will be liquefied in the high-temperature condenser 103, changing from gas to liquid. After the liquid passes through the high-temperature filter 104 and the high-temperature sight glass 110 in turn, it is divided into two paths again, one of which passes through the high-temperature main refrigeration path, and the other passes through the liquid spray cooling path.

[0057] like Figure 4 As shown, the liquid in the high-temperature main refrigeration circuit becomes a two-phase vapor-liquid coexistence body after passing through the high-temperature main solenoid valve 301 and the high-temperature thermal expansion valve 302. The two-phase vapor-liquid coexistence body enters the high-temperature channel 105a of the dual-channel intercooler 105, and evaporates in the high-temperature channel 105a to absorb the heat generated by the refrigerant of the low-temperature system during the condensation process, thereby becoming a low-temperature and low-pressure superheated gas. The low-temperature and low-pressure superheated gas enters the high-temperature gas-liquid separator 106, and returns to the high-temperature compressor 101 after passing through the high-temperature gas-liquid separator 106.

[0058] like Figure 5 As shown, in one embodiment of the present application, the deep-freeze high and low temperature box refrigeration system using hot gas bypass also includes a high-temperature stage liquid spray cooling regulating valve 107, the inlet of the high-temperature stage liquid spray cooling regulating valve 107 is connected to the outlet of the high-temperature stage filter 104, and the outlet of the high-temperature stage liquid spray cooling regulating valve 107 is connected to the inlet of the high-temperature stage gas-liquid separator 106.

[0059] Specifically, flash evaporation is a phenomenon in which a high-pressure saturated liquid enters a relatively low-pressure container and, due to a sudden drop in pressure, the saturated liquid becomes a portion of saturated steam and saturated liquid under the container pressure.

[0060] In this embodiment, Figure 5 As shown, the liquid in the liquid spray cooling circuit merges with the hot gas bypass gas coming out of the outlet of the high-temperature stage hot gas bypass regulating valve 202 after passing through the high-temperature stage liquid spray cooling regulating valve 107. During the merging process, the liquid in the liquid spray cooling circuit flashes into gas and enters the high-temperature stage gas-liquid separator 106, and returns to the high-temperature stage compressor 101 after passing through the high-temperature stage gas-liquid separator 106.

[0061] like Figure 7As shown, in one embodiment of the present application, the low-temperature stage hot gas bypass passage 500 also includes a second channel 501, a low-temperature stage hot gas bypass solenoid valve 502, a low-temperature stage hot gas bypass regulating valve 503 and a bypass pressure sensor 504, one end of the second channel 501 is connected to the outlet of the low-temperature stage compressor 401, the other end of the second channel 501 is connected to the inlet of the low-temperature stage oil separator 402, one end of the low-temperature stage hot gas bypass solenoid valve 502 is connected to the outlet of the low-temperature stage oil separator 402, the other end of the low-temperature stage hot gas bypass solenoid valve 502 is connected to the inlet of the low-temperature stage hot gas bypass regulating valve 503, the low-temperature stage hot gas bypass regulating valve 503 is connected to the second inlet 105e of the dual-channel intermediate cooling room, and the bypass pressure sensor 504 is arranged between the second outlet of the dual-channel intermediate cooling room and the inlet of the refrigeration evaporator 404.

[0062] In this embodiment, the low-temperature oil separator 402 separates the refrigerant input from the low-temperature stage into two parts: oil and gas. The excess oil separated by the low-temperature oil separator 402 is transported back to the low-temperature compressor 401 through the second channel 501, and the gas separated from the low-temperature oil separator 402 is divided into two paths, one of which is the main refrigeration circuit and the other is the low-temperature hot gas bypass.

[0063] like Figure 7 As shown, when the low-temperature stage hot gas bypass solenoid valve 502 is opened, the high-temperature and high-pressure low-temperature stage hot gas bypass gas passes through the low-temperature stage hot gas bypass solenoid valve 502 and the low-temperature stage hot gas bypass regulating valve 503, and the high-temperature and high-pressure low-temperature stage hot gas bypass gas is converted into the low-temperature stage hot gas bypass gas with reduced pressure but substantially unchanged temperature, and then the low-temperature stage hot gas bypass gas with reduced pressure but substantially unchanged temperature enters the hot gas bypass channel 105c of the dual-channel intercooler 105 through the second inlet 105e, and the low-temperature stage hot gas bypass gas with reduced pressure but substantially unchanged temperature is converted into the low-temperature stage hot gas bypass gas with low temperature but unchanged pressure in the hot gas bypass channel 105c. The low-temperature but pressure-constant low-temperature hot gas bypass gas merges with the low-temperature and low-pressure superheated gas coming out of the refrigeration evaporator 404, thereby merging into a whole and entering the low-temperature gas-liquid separator 405. Since the temperature and pressure of the low-temperature and low-pressure superheated gas coming out of the refrigeration evaporator 404 are almost the same as the temperature and pressure of the low-temperature but pressure-constant low-temperature hot gas bypass gas coming out of the hot gas bypass channel 105c of the dual-channel intercooler 105, when the two gases pass through the low-temperature gas-liquid separator 405 and return to the inlet of the low-temperature compressor 401, they will not cause fluctuations in the temperature and pressure of the low-temperature compressor 401.

[0064] The hot gas bypass passage 105c is filled with gas from the low-temperature hot gas bypass passage. After passing through the dual-channel intercooler 105, the gas will be evaporated by the high-temperature refrigerant with heat and become gas with the same evaporation temperature, for example, -20°C. The temperature of -20°C is lower than the original temperature.

[0065] The reason why the gas in the hot gas bypass channel 105c is not condensed into gas like the gas in the low-temperature channel 105b is that the gas entering the hot gas bypass channel 105c passes through the low-temperature hot gas bypass solenoid valve 502 and the low-temperature hot gas bypass regulating valve 503 before entering the dual-channel intercooler 105.

[0066] For example, in a typical cascade system, the high-temperature refrigerant condenses at 40°C and evaporates at -20°C, and the low-temperature refrigerant evaporates at -70°C and condenses at -15°C. The exhaust temperature of the low-temperature system is generally around 90°C, and the suction air, due to the heat absorption of the pipeline, often rises to around -30°C from the -60°C at the outlet of the refrigeration evaporator 404 to the low-temperature compressor.

[0067] After the hot gas bypass of the original design is turned on, the pre-cooling heat exchanger 403 can first cool the 90°C hot gas to the water temperature of 32°C, and then directly return to the low-temperature compressor. If the system is switched between the main cooling and hot gas bypass, the return air temperature is 32°C when the hot gas bypass is turned on, which is bound to easily cause the exhaust temperature to be too high. If the system is turned on at the same time as the main cooling and hot gas bypass, the return air temperature of the low-temperature compressor after the confluence exceeds 5°C, so the exhaust temperature rises to 110°C, and further rises with time until the exhaust temperature is too high. When the exhaust temperature is too high, the original design will trigger liquid spray cooling, which will cause problems such as pressure fluctuations and compressor frost.

[0068] In the present application, the exhaust gas of the hot gas bypass of the low-temperature compressor is adjusted by the low-temperature hot gas bypass solenoid valve 502 and the low-temperature hot gas bypass regulating valve 503, so that the outflowing gas pressure can be adjusted to, for example, the saturation pressure corresponding to -40°C. Since in the dual-channel intercooler 105, the heat of the low-temperature main refrigeration circuit and the hot gas bypass gas is taken away by the evaporation of the high-temperature refrigerant, and the evaporation temperature of the high-temperature refrigerant is -20°C, the hot gas bypass gas will be directly cooled from 90°C to close to -20°C. In this way, for the saturation pressure corresponding to -40°C, it is still in an overheated state at a temperature of -20°C, with a superheat degree of 20K, and therefore it will not be cooled into liquid.

[0069] like Figure 8As shown, in one embodiment of the present application, the first low-temperature stage liquid separation passage 600 also includes a low-temperature stage high-pressure pressure sensor 601, a low-temperature stage filter 602, a low-temperature stage refrigeration solenoid valve 603 and a low-temperature stage thermal expansion valve 604, the low-temperature stage high-pressure pressure sensor 601 is arranged between the outlet of the pre-cooling heat exchanger 403 and the first inlet 105d of the dual-channel intercooler 105, the inlet of the low-temperature stage filter 602 is connected to the first outlet of the dual-channel intercooler 105, the outlet of the low-temperature stage filter 602 is connected to the inlet of the low-temperature stage refrigeration solenoid valve 603, and the outlet of the low-temperature stage refrigeration solenoid valve 603 is connected to the outlet of the low-temperature stage thermal expansion valve 604.

[0070] In this embodiment, when the low-temperature hot gas bypass solenoid valve 502 is closed, all the gas separated from the low-temperature oil separator 402 enters the pre-cooling heat exchanger 403, and the gas is cooled in the pre-cooling heat exchanger 403. The cooled gas enters the low-temperature channel 105b of the dual-channel intermediate cooling plate, thereby condensing the cooled gas into liquid. Thereafter, the liquid passes through the low-temperature filter 602 and the low-temperature refrigeration solenoid valve 603 in sequence. After passing through the low-temperature thermal expansion valve 604, the liquid becomes a two-phase vapor-liquid coexistence body. The two-phase vapor-liquid coexistence body enters the refrigeration evaporator 404, thereby absorbing the temperature of the target box, so that the two-phase vapor-liquid coexistence body becomes a low-temperature and low-pressure superheated gas.

[0071] like Fig. 9 As shown, in one embodiment of the present application, the cryogenic high and low temperature box refrigeration system using hot gas bypass also includes a second low temperature stage liquid separation passage 700, and the second low temperature stage liquid separation passage 700 is arranged between the outlet of the precooling heat exchanger 403 and the inlet of the low temperature stage gas-liquid separator 405, and the second low temperature stage liquid separation passage 700 includes a pressure relief solenoid valve 701 and an expansion tank 702, the inlet of the pressure relief solenoid valve 701 is connected to the outlet of the precooling heat exchanger 403, the outlet of the pressure relief solenoid valve 701 is connected to the inlet of the expansion tank 702, and the outlet of the expansion tank 702 is connected to the inlet of the low temperature stage gas-liquid separator 405.

[0072] Specifically, a capillary tube is provided between the expansion tank 702 and the low-temperature gas-liquid separator 405 .

[0073] In this embodiment, when the high-temperature system and the low-temperature system are shut down, the refrigerant in the low-temperature system will absorb ambient heat and evaporate into gas, which will cause the pressure in the low-temperature system to rise, so the expansion tank 702 is used to contain these gases, and the pressure relief solenoid valve 701 is set to a normally open state. When the high-temperature system and the low-temperature system are shut down, the system is delayed in closing when it is running, and the refrigerant gas in the expansion tank 702 will be gradually sucked into the system through the capillary.

[0074] like Figure 4 As shown, in one embodiment of the present application, the high-temperature refrigeration circuit 100 also includes a high-temperature low-pressure pressure switch 108 and a high-temperature high-pressure pressure switch 109, the high-temperature low-pressure pressure switch 108 is arranged close to the inlet of the high-temperature compressor 101, and the high-temperature high-pressure pressure switch 109 is arranged close to the outlet of the high-temperature compressor 101.

[0075] In this embodiment, the opening and closing of the inlet of the high-temperature compressor 101 is controlled by the high-temperature low-pressure switch 108, and the opening and closing of the outlet of the high-temperature compressor 101 is controlled by the high-temperature high-pressure switch 109.

[0076] like Figure 6 As shown, in one embodiment of the present application, the low-temperature refrigeration circuit 400 also includes a low-temperature low-pressure pressure switch 406 and a low-temperature high-pressure pressure switch 407, the low-temperature low-pressure pressure switch 406 is arranged close to the inlet of the low-temperature compressor 401, and the low-temperature high-pressure pressure switch 407 is arranged close to the outlet of the low-temperature compressor 401.

[0077] In this embodiment, the opening and closing of the inlet of the low-temperature stage compressor 401 is controlled by the low-temperature stage low-pressure pressure switch 406, and the opening and closing of the outlet of the low-temperature stage compressor 401 is controlled by the high-temperature stage high-pressure pressure switch.

[0078] like Fig.10 As shown, in one embodiment of the present application, the dual-channel intercooler 105 includes a high-temperature stage channel 105a, a low-temperature stage channel 105b and a hot gas bypass channel 105c, the high-temperature stage channel 105a is arranged between the low-temperature stage channel 105b and the hot gas bypass channel 105c, the high-temperature stage inlet is connected to the high-temperature stage channel 105a, the first inlet 105d is connected to the low-temperature stage channel 105b, and the second inlet 105e is connected to the hot gas bypass channel 105c.

[0079] Specifically, a dual-channel intercooler 105 is used as an intercooler, but the structure of the dual-channel intercooler 105 is slightly enlarged, and the overall design of the high and low temperature box is improved, so that the spray cooling pipeline and valve of the low-temperature stage system can be eliminated, because the stable return air temperature can ensure the temperature stability of the exhaust temperature.

[0080] This simplifies the structure of the low-temperature system to a certain extent, and the cost of the removed liquid spray cooling pipeline and valve is obviously greater than the increased cost of using a dual-channel plate exchanger, thereby achieving cost savings.

[0081] In addition, the hot gas bypass gas pipeline is separated and directly enters the dual-channel intercooler 105 before entering the pre-cooling heat exchanger 403, for example, entering at 90°C instead of being cooled to 32°C by water. In this way, the specifications of the pre-cooling heat exchanger 403 can be further reduced, thereby reducing costs.

[0082] In this embodiment, since the high-temperature channel 105a is arranged in the middle, when the gas enters the low-temperature channel 105b, it will be condensed into liquid by the refrigeration effect generated by the evaporation of the refrigerant in the high-temperature channel 105a on the middle side.

[0083] After the gas enters the hot gas bypass channel 105c, it will also be affected by the refrigeration effect generated by the evaporation of the refrigerant in the high-temperature stage channel 105a on the middle side, thereby reducing the temperature of the gas.

[0084] The present application is based on the particularity of energy regulation application of the cascade refrigeration system of the cryogenic high and low temperature box. Aiming at the hot gas bypass method commonly used in its low temperature system, the dual-channel intercooler 105 is used as an intercooler and the pressure regulating device (such as the suction pressure regulating valve) for controlling the outlet pressure is used together to cool the gas temperature of the hot gas bypass of the low temperature stage to a lower temperature, thereby ensuring the safety of the exhaust temperature and the stability of the system pressure when the hot gas bypass is used in the low temperature stage.

[0085] In the original design, when the low-temperature system uses hot gas bypass, it is very easy to cause the exhaust temperature to rise, which in turn triggers the liquid spray cooling. Liquid spray cooling itself is a relatively difficult device to accurately control, and it is very easy to over-spray, which causes frost on the compressor suction port. Even a small amount of liquid spray itself will flash into a large amount of gas, causing a rapid increase in the suction side pressure, and at the same time, it will also increase the evaporation temperature of the refrigeration evaporator 404, which will cause temperature fluctuations in the high and low temperature boxes. This series of chain reactions are all detrimental to the final refrigeration effect.

[0086] In the present application, first, the temperature of the hot gas bypass is significantly reduced to be close to the return air temperature of the refrigeration evaporator 404, and the pressure of the hot gas bypass can be adjusted as needed to be close to the pressure of the gas coming out of the refrigeration evaporator 404. In this way, when the hot gas bypass gas returns to the low-temperature compressor 401, the change in the temperature and pressure of the return air is extremely small, so the system can maintain stable operation.

[0087] The technical features of the above-described embodiments may be arbitrarily combined, and the execution order of the method steps is not limited. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0088] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A cryogenic high and low temperature box refrigeration system using hot gas bypass, characterized in that: The cryogenic high and low temperature box refrigeration system using hot gas bypass comprises: A high-temperature refrigeration circuit, the high-temperature refrigeration circuit comprising a high-temperature compressor, a high-temperature oil separator, a high-temperature condenser, a high-temperature filter, a dual-channel intercooler and a high-temperature gas-liquid separator connected in sequence; A high-temperature hot gas bypass passage, wherein the high-temperature hot gas bypass passage is disposed between the high-temperature oil separator and the high-temperature gas-liquid separator, and the outlet of the high-temperature oil separator is connected to the inlet of the high-temperature gas-liquid separator through the high-temperature hot gas bypass passage; a first high-temperature-stage liquid separation passage, wherein the first high-temperature-stage liquid separation passage is disposed between the high-temperature-stage filter and the dual-channel intercooler, and the outlet of the high-temperature-stage filter is connected to the high-temperature-stage inlet of the dual-channel intercooler through the first high-temperature-stage liquid separation passage; A low-temperature refrigeration circuit, the low-temperature refrigeration circuit comprising a low-temperature compressor, a low-temperature oil separator, a precooling heat exchanger, a dual-channel intercooler, a refrigeration evaporator and a low-temperature gas-liquid separator connected in sequence; A low-temperature hot gas bypass passage, wherein the low-temperature hot gas bypass passage comprises a low-temperature compressor, a low-temperature oil separator, a dual-channel intercooler, a refrigeration evaporator and a low-temperature gas-liquid separator connected in sequence; The first low-temperature liquid separation passage comprises a precooling heat exchanger, a dual-channel intercooler, a refrigeration evaporator and a low-temperature gas-liquid separator which are connected in sequence.

2. The cryogenic high and low temperature box refrigeration system using hot gas bypass according to claim 1, characterized in that: The high-temperature hot gas bypass passage includes a high-temperature hot gas bypass solenoid valve and a high-temperature hot gas bypass regulating valve. The inlet of the high-temperature hot gas bypass solenoid valve is connected to the outlet of the high-temperature oil separator, the outlet of the high-temperature hot gas bypass solenoid valve is connected to the inlet of the high-temperature hot gas bypass regulating valve, and the outlet of the high-temperature hot gas bypass regulating valve is connected to the inlet of the high-temperature gas-liquid separator.

3. The cryogenic high and low temperature box refrigeration system using hot gas bypass according to claim 2, characterized in that: The first high-temperature stage liquid separation passage includes a high-temperature stage main solenoid valve and a high-temperature stage thermal expansion valve. The inlet of the high-temperature stage main solenoid valve is connected to the outlet of the high-temperature stage filter, the outlet of the high-temperature stage main solenoid valve is connected to the inlet of the high-temperature stage thermal expansion valve, and the outlet of the high-temperature stage thermal expansion valve is connected to the high-temperature stage inlet of the dual-channel intercooler.

4. The cryogenic high and low temperature box refrigeration system using hot gas bypass according to claim 3 is characterized in that: The cryogenic high and low temperature box refrigeration system using hot gas bypass also includes: A high-temperature liquid spray cooling regulating valve, wherein the inlet of the high-temperature liquid spray cooling regulating valve is connected to the outlet of the high-temperature filter, and the outlet of the high-temperature liquid spray cooling regulating valve is connected to the inlet of the high-temperature gas-liquid separator.

5. The cryogenic high and low temperature box refrigeration system using hot gas bypass according to claim 4, characterized in that: The low-temperature hot gas bypass passage also includes a second channel, a low-temperature hot gas bypass solenoid valve, a low-temperature hot gas bypass regulating valve and a bypass pressure sensor. One end of the second channel is connected to the outlet of the low-temperature compressor, and the other end of the second channel is connected to the inlet of the low-temperature oil separator. One end of the low-temperature hot gas bypass solenoid valve is connected to the outlet of the low-temperature oil separator, and the other end of the low-temperature hot gas bypass solenoid valve is connected to the inlet of the low-temperature hot gas bypass regulating valve. The low-temperature hot gas bypass regulating valve is connected to the second inlet of the dual-channel intermediate cooling room, and the bypass pressure sensor is arranged between the second outlet of the dual-channel intermediate cooling room and the inlet of the refrigeration evaporator.

6. The cryogenic high and low temperature box refrigeration system using hot gas bypass according to claim 5, characterized in that: The first low-temperature liquid separation passage also includes a low-temperature high-pressure pressure sensor, a low-temperature filter, a low-temperature refrigeration solenoid valve and a low-temperature thermal expansion valve. The low-temperature high-pressure pressure sensor is arranged between the outlet of the pre-cooling heat exchanger and the first inlet of the dual-channel intercooler, the inlet of the low-temperature filter is connected to the first outlet of the dual-channel intercooler, the outlet of the low-temperature filter is connected to the inlet of the low-temperature refrigeration solenoid valve, and the outlet of the low-temperature refrigeration solenoid valve is connected to the outlet of the low-temperature thermal expansion valve.

7. The cryogenic high and low temperature box refrigeration system using hot gas bypass according to claim 6, characterized in that: The cryogenic high and low temperature box refrigeration system using hot gas bypass also includes: The second low-temperature stage liquid separation passage is arranged between the outlet of the precooling heat exchanger and the inlet of the low-temperature stage gas-liquid separator. The second low-temperature stage liquid separation passage includes a pressure relief solenoid valve and an expansion tank. The inlet of the pressure relief solenoid valve is connected to the outlet of the precooling heat exchanger, the outlet of the pressure relief solenoid valve is connected to the inlet of the expansion tank, and the outlet of the expansion tank is connected to the inlet of the low-temperature stage gas-liquid separator.

8. The cryogenic high and low temperature box refrigeration system using hot gas bypass according to claim 7, characterized in that: The high temperature refrigeration circuit also includes: A high temperature stage low pressure switch and a high temperature stage high pressure switch, wherein the high temperature stage low pressure switch is arranged close to the inlet of the high temperature stage compressor, and the high temperature stage high pressure switch is arranged close to the outlet of the high temperature stage compressor.

9. The cryogenic high and low temperature box refrigeration system using hot gas bypass according to claim 8, characterized in that: The low temperature refrigeration circuit also includes: A cryogenic low-pressure switch and a cryogenic high-pressure switch, wherein the cryogenic low-pressure switch is arranged close to the inlet of the cryogenic compressor, and the cryogenic high-pressure switch is arranged close to the outlet of the cryogenic compressor.

10. The cryogenic high and low temperature box refrigeration system using hot gas bypass according to claim 9, characterized in that: The dual-channel intercooler includes a high-temperature stage channel, a low-temperature stage channel and a hot gas bypass channel. The high-temperature stage channel is arranged between the low-temperature stage channel and the hot gas bypass channel. The high-temperature stage inlet is connected to the high-temperature stage channel, the first inlet is connected to the low-temperature stage channel, and the second inlet is connected to the hot gas bypass channel.

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