An ultra-low temperature refrigeration system

Abstract

The application relates to the field of refrigeration technology, in particular to an ultralow-temperature refrigeration system, which comprises a compressor, a condenser, a drying filter, a first gas-liquid separator, a high-temperature regenerator, a second gas-liquid separator, an intermediate regenerator, a low-temperature regenerator and an evaporation coil in sequence; each gas-liquid separator is provided with a gas-phase inlet, a gas-phase outlet and a liquid-phase outlet; and each regenerator is provided with two inlets and two outlets. The scheme sets one compressor, can realize self-recovery closed circulation, occupies small space and has high refrigeration efficiency.

Description

Technical Field

[0001] This invention relates to the field of refrigeration technology, specifically an ultra-low temperature refrigeration system. Background Technology

[0002] In recent years, ultra-low temperature sample storage chambers have become increasingly common in the medical and scientific research fields. According to the national standard GB / T20154-2024, low-temperature chambers are defined as -25℃, -30℃, -40℃, -50℃, -60℃, -86℃, -140℃, -150℃, and -164℃. The -86℃ ultra-low temperature chamber is currently the most widely used on the market. Depending on the application scenario, it can stably and continuously maintain the internal temperature within the range of -86±5℃ in insulated chambers with volumes ranging from 20 to 800 L. Traditionally, deep cryogenic systems generally employ a dual-compressor cascade refrigeration system, achieving ultra-low temperature cooling through the coordinated operation of high-temperature and low-temperature stages.

[0003] In the patents published under CN121677283A and CN121112509A, two compressors are used in each refrigeration system to achieve the deep cryogenic range, and cooling water is used in the cooling system. These systems not only occupy a lot of space but also have high input power, resulting in relatively low refrigeration efficiency. Therefore, developing an ultra-low temperature system and device with a smaller footprint and lower input power is of great significance. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides an ultra-low temperature refrigeration system that employs a single compressor in a self-circulating manner, thus solving the issues of traditional refrigeration systems where equipment occupies a lot of space and has high input power but low efficiency.

[0005] An ultra-low temperature refrigeration system includes a compressor, a condenser, a dryer filter, a first gas-liquid separator, a high-temperature regenerator, a second gas-liquid separator, an intermediate regenerator, a low-temperature regenerator, and an evaporator coil connected in sequence; each gas-liquid separator has a gas phase inlet, a gas phase outlet, and a liquid phase outlet, and each regenerator has two inlets and two outlets; In the refrigeration direction: the compressor outlet is connected to the condenser inlet, the condenser outlet is connected to the dryer filter inlet, the dryer filter outlet is connected to the gas phase inlet of the first gas-liquid separator, the gas phase outlet of the first gas-liquid separator is connected to the inlet a of the high-temperature regenerator, the outlet d of the high-temperature regenerator is connected to the gas phase inlet of the second gas-liquid separator, the gas phase outlet of the second gas-liquid separator is connected to the inlet e of the intermediate regenerator, the intermediate regenerator is connected in series with the low-temperature regenerator, and the outlet k of the low-temperature regenerator is connected to the low-pressure cold air inlet of the evaporator coil via a third capillary tube; In the loop direction: the outlet of the evaporator coil is connected to the inlet j of the low-temperature regenerator, and then through the outlet f of the intermediate regenerator to the inlet c of the high-temperature regenerator; the liquid phase outlet of the first gas-liquid separator is connected to the inlet c of the high-temperature regenerator through the first capillary tube; the liquid phase outlet of the second gas-liquid separator is connected to the inlet g of the intermediate regenerator through the second capillary tube, and then through the outlet f of the intermediate regenerator to the inlet c of the high-temperature regenerator; and then they all return to the low-pressure suction inlet of the compressor through the outlet b of the high-temperature regenerator.

[0006] In the aforementioned cryogenic refrigeration system, the compressor is connected in parallel with a pressure relief pipeline, and a balance tank and a buffer capillary tube are connected in series on the pressure relief pipeline. The balance tank is equipped with a high-pressure control valve and a low-pressure control valve at its inlet and outlet, respectively. A high-pressure transmitter is installed at the high-pressure outlet of the compressor, and a low-pressure transmitter is installed at the low-pressure inlet. The high-pressure transmitter is used to monitor the compressor's discharge pressure and feed the pressure value back to the high-pressure control valve to control the connection of the balance tank. The low-pressure transmitter is used to monitor the compressor's suction pressure and feed the pressure value back to the low-pressure control valve to control the connection between the balance tank and the buffer capillary tube.

[0007] The beneficial effects of this invention are: this solution is equipped with a compressor, which can self-close the loop, occupy little space and has high cooling efficiency. Attached Figure Description

[0008] Figure 1 This is a schematic diagram illustrating the principle of an embodiment of the present invention; Figure 2 This is a schematic diagram of the high-pressure switch control logic according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the low-pressure switch control logic according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the regenerator connection structure according to an embodiment of the present invention; Figure 5 This is the ambient temperature drop curve during the operation of an embodiment of the present invention; Figure 6 This is the intake / exhaust pressure curve of the compressor during operation in an embodiment of the present invention.

[0009] Figure label: 101-Compressor; 102-Buffer capillary tube; 103-Cooling fan; 104-High pressure control valve; 105-Balance tank; 106-Condenser; 107-Drier filter; 108-Low pressure control valve; 109-High pressure transmitter; 110-Low pressure transmitter; 201-First-stage gas-liquid separator; 202-First-stage capillary tube; 203-High-temperature regenerator; 204-Second-stage gas-liquid separator; 205-Intermediate regenerator; 206-Low-temperature regenerator; 207-Second-stage capillary tube; 208 T-connector; 301 - Tertiary capillary tube; 302 - Evaporation coil; 303 - Temperature sensor. Detailed Implementation

[0010] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings. The following embodiments are illustrative; unless otherwise specifically stated, the relative arrangement and numerical expressions of components and steps described in these embodiments should not be construed as limiting the scope of the present invention. The following description of exemplary embodiments is merely illustrative and should not be construed as limiting the present invention or its application or use in any way. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail here, but where applicable, such techniques, methods, and apparatus should be considered part of this specification.

[0011] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form, and when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. Unless otherwise stated, the terms "installed," "connected," "linked," etc., in this invention should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to an internal connection between two elements or an interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0012] For ease of description, the present invention uses directional descriptions such as "upper," "lower," "left," "right," "front," "back," "bottom," and "top," which do not limit the structure. They are merely for the purpose of understanding the structural principle of the present invention in conjunction with the accompanying drawings, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limitations on the present invention.

[0013] This embodiment is an ultra-low temperature refrigeration system, such as Figure 1As shown, the system includes a compressor 101, a condenser 106, a dryer filter 107, a first gas-liquid separator 201, a high-temperature regenerator 203, a second gas-liquid separator 204, an intermediate regenerator 205, a low-temperature regenerator 206, and an evaporator coil 302 connected in sequence. Each gas-liquid separator has a gas phase inlet, a gas phase outlet, and a liquid phase outlet, and each regenerator has two inlets and two outlets.

[0014] In the refrigeration direction: the outlet of compressor 101 is high pressure, which is connected to the inlet of condenser 106. The condenser 106 is equipped with a fan 103 for cooling the working fluid flowing inside. The outlet of condenser 106 is connected to the inlet of dryer filter 107. The outlet of dryer filter 107 is connected to the gas phase inlet of first gas-liquid separator 201. The gas phase outlet of first gas-liquid separator 201 is connected to the inlet a of high-temperature regenerator 203. The outlet d of high-temperature regenerator 203 is connected to the gas phase inlet of second gas-liquid separator 204. The gas phase outlet of second gas-liquid separator 204 is connected to the inlet e of intermediate regenerator 205. Intermediate regenerator 205 is connected in series with low-temperature regenerator 206. The outlet k of low-temperature regenerator 206 is cooled and depressurized by third capillary tube 301 and then connected to the low-pressure cold air inlet of evaporator coil 302.

[0015] In the loop direction: the outlet of the evaporator coil 302 is connected to the inlet j of the low-temperature regenerator 206, and then through the outlet f of the intermediate regenerator 205 to the inlet c of the high-temperature regenerator 203; the liquid phase outlet of the first gas-liquid separator 201 is connected to the inlet c of the high-temperature regenerator 203 through the first capillary tube 202; the liquid phase outlet of the second gas-liquid separator 204 is connected to the inlet g of the intermediate regenerator 205 (which is also the outlet of the high-temperature regenerator 203 connected in series) through the second capillary tube 207, and through the intermediate regenerator 205, it is also through the outlet f of the intermediate regenerator 205 to the inlet c of the high-temperature regenerator 203; then they all return to the low-pressure suction inlet of the compressor 101 through the outlet b of the high-temperature regenerator 203.

[0016] Furthermore, the compressor 101 is connected in parallel with a pressure relief pipeline, and the pressure relief pipeline is provided with a balance tank 105 and a buffer capillary tube 102 connected in series. The balance tank 105 is provided with a high pressure control valve 104 and a low pressure control valve 108 at its inlet and outlet, respectively.

[0017] A high-pressure transmitter 109 is installed at the high-pressure outlet of the compressor 101, and a low-pressure transmitter 110 is installed at the low-pressure inlet.

[0018] The high-pressure transmitter 109 is used to monitor the discharge pressure of the compressor 101 and feed the pressure value back to the high-pressure control valve 104 to control the connection of the balance tank 105, such as... Figure 2As shown, the specific process is as follows: When the high-pressure transmitter 109 monitors an exhaust pressure ≥ 26 bar, the high-pressure control valve 104 opens, partially releasing the high-pressure gas into the balance tank 105. This ensures that the exhaust pressure of the compressor 101 is within a suitable range, preventing the compressor 101 from automatically shutting down due to excessive pressure. Furthermore, excessively high exhaust pressure will also lead to excessively high exhaust temperature, which will also cause a shutdown. When the high-pressure transmitter 109 detects an exhaust pressure < 26 bar, the high-pressure control valve 104 closes.

[0019] The low-pressure transmitter 110 is used to monitor the suction pressure of the compressor 101 and feeds back the pressure value to the low-pressure control valve 108 to control the connection between the balance tank 105 and the buffer capillary tube 102. Figure 3 As shown, the specific process is as follows: when the low-pressure transmitter 110 monitors the suction pressure ≥ 6 bar, the low-pressure control valve 108 is closed to prevent the compressor 101 from being damaged due to excessive back pressure; when the low-pressure transmitter 110 monitors the suction pressure < 5 bar, the low-pressure control valve 108 is opened to allow the gas in the balance tank 105 to be depressurized to the compressor 101 through the buffer capillary tube 102, ensuring that the system has enough working fluid to operate.

[0020] The condenser 106 is preferably an aluminum microchannel condenser, but it can also be a copper tube aluminum finned condenser. The structure of the high-temperature regenerator 203, intermediate regenerator 205, and low-temperature regenerator 206 is not limited; they can be plate heat exchangers, shell-and-tube heat exchangers, etc. The connection between the intermediate regenerator 205 and the low-temperature regenerator 206 can be reasonably varied according to the structure of the heat exchangers: if both the intermediate regenerator 205 and the low-temperature regenerator 206 are separate plate heat exchangers or shell-and-tube heat exchangers, then... Figure 1 The two can be connected by pipes g and h; if the intermediate regenerator 205 and the low-temperature regenerator 206 are a large integrated shell-and-tube heat exchanger, as shown. Figure 4 As shown, intermediate pipes g and h can be omitted, and the connection can be achieved directly in the middle of the shell-and-tube heat exchanger via a tee joint 208. The preferred connection location for the tee joint 208 is approximately 1 / 15 to 1 / 20 of the total length from the inner tube end. The heat exchange area of ​​the high-temperature regenerator 203 is preferably 0.2 to 0.3 m², the intermediate regenerator 205 is preferably 0.02 to 0.03 m², and the low-temperature regenerator 206 is preferably 0.5 to 0.8 m². Their arrangement is preferably within the insulation layer at the bottom of the cryogenic device. The insulation layer structure is preferably polyurethane foam + VIP insulation board, with a polyurethane foam density of 40 to 50 kg / m³, and the VIP insulation board is attached to the outer side of the insulation box.

[0021] The inner diameters of the first capillary 202, the second capillary 207, and the third capillary 301 are in the range of 1 to 1.5 mm, and their lengths are in the range of 1 to 6 m; wherein preferably, the inner diameter of the first capillary 202 is 1 mm and its length is 1.5 to 2.5 m; the inner diameter of the second capillary 207 is 1 mm and its length is 2 to 3 m; and the inner diameter of the third capillary 301 is 1.5 mm and its length is 5 to 6 m.

[0022] In this embodiment, the evaporator coil 302 is preferably 40-50 meters long, and its outer diameter is specified as follows: Inner diameter=10 8. Its cross-sectional shape can be O-shaped or D-shaped, with D-shaped copper tubes being preferred. The D-shaped plane is tightly fitted to the outer side of the inner liner of the cryogenic device, increasing the contact area and improving heat exchange efficiency.

[0023] refer to Figure 5 Monitoring of the internal ambient temperature of the ultra-low temperature insulation chamber during system operation shows that, using the solution of this invention, the internal temperature of the chamber can be reduced to -86℃ within 7 hours when the ambient temperature is 25~28℃, and the lowest temperature can be reduced to -88℃. The maintainable temperature range fully complies with the application scenario of -86℃ in the national standard GB / T 20154-2024. In the actual product's dual-system simultaneous cooling operation (one backup and one active), when the ambient temperature is maintained at 25±1℃, it can be inferred that the overall cooling time will be <3.5 hours.

[0024] refer to Figure 6 By monitoring the compressor's exhaust / intake pressure during the pressure control valve disconnection logic process in the embodiment, it can be seen that the compressor 101's exhaust and intake pressures fluctuate greatly at the beginning of the system. After 1 hour, the system pressure gradually stabilizes within a reasonable range.

[0025] The above are merely preferred embodiments of this application. It should be noted that, for those skilled in the art, several structural changes or improvements can be made without departing from the principles of this application, and these changes or improvements should also be considered within the scope of protection of this application.

Claims

1. An ultra-low temperature refrigeration system, characterized in that: It includes a compressor (101), a condenser (106), a dryer filter (107), a first gas-liquid separator (201), a high-temperature regenerator (203), a second gas-liquid separator (204), an intermediate regenerator (205), a low-temperature regenerator (206), and an evaporator coil (302) connected in sequence; each gas-liquid separator has a gas phase inlet, a gas phase outlet, and a liquid phase outlet, and each regenerator has two inlets and two outlets; In the refrigeration direction: the outlet of the compressor (101) is connected to the inlet of the condenser (106), the outlet of the condenser (106) is connected to the inlet of the dryer filter (107), the outlet of the dryer filter (107) is connected to the gas phase inlet of the first gas-liquid separator (201), the gas phase outlet of the first gas-liquid separator (201) is connected to the inlet a of the high temperature regenerator (203), the outlet d of the high temperature regenerator (203) is connected to the gas phase inlet of the second gas-liquid separator (204), the gas phase outlet of the second gas-liquid separator (204) is connected to the inlet e of the intermediate regenerator (205), the intermediate regenerator (205) is connected in series with the low temperature regenerator (206), and the outlet k of the low temperature regenerator (206) is connected to the low-pressure cold air inlet of the evaporator coil (302) via the third capillary tube (301). In the loop direction: the outlet of the evaporator coil (302) is connected to the inlet j of the low-temperature regenerator (206), and then through the outlet f of the intermediate regenerator (205) to the inlet c of the high-temperature regenerator (203); the liquid phase outlet of the first gas-liquid separator (201) is connected to the inlet c of the high-temperature regenerator (203) through the first capillary tube (202); the liquid phase outlet of the second gas-liquid separator (204) is connected to the inlet g of the intermediate regenerator (205) through the second capillary tube (207), and through the outlet f of the intermediate regenerator (205) to the inlet c of the high-temperature regenerator (203); then they all return to the low-pressure suction inlet of the compressor (101) through the outlet b of the high-temperature regenerator (203).

2. The cryogenic refrigeration system according to claim 1, characterized in that: The compressor (101) is connected in parallel with a pressure relief pipeline. The pressure relief pipeline is equipped with a balance tank (105) and a buffer capillary tube (102) connected in series. The balance tank (105) is equipped with a high-pressure control valve (104) and a low-pressure control valve (108) at its inlet and outlet, respectively. A high-pressure transmitter (109) is installed at the high-pressure outlet of the compressor (101), and a low-pressure transmitter (110) is installed at the low-pressure inlet. The high-pressure transmitter (109) is used to monitor the discharge pressure of the compressor (101) and feed the pressure value back to the high-pressure control valve (104) to control the connection of the balance tank (105). The low-pressure transmitter (110) is used to monitor the suction pressure of the compressor (101) and feed the pressure value back to the low-pressure control valve (108) to control the connection between the balance tank (105) and the buffer capillary tube (102).

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