Low-temperature refrigerator

Abstract

According to the low-temperature refrigerator provided by the utility model, a normal-temperature and normal-pressure gas working medium is compressed to a high-pressure state by the compressor, the compressed gas flows through the water cooler to be pre-cooled, and the pre-cooled gas enters the high-pressure surge tank, is subjected to heat exchange by the dividing wall type cold accumulation heat exchanger and then enters the expansion machine to be subjected to expansion refrigeration; the expanded refrigeration working medium is guided into the cold energy heat exchanger to absorb and utilize cold energy, and the gas working medium discharged from the cold energy heat exchanger absorbs heat and is heated through the dividing wall type cold accumulation heat exchanger and then returns to the compressor through the low-pressure surge tank, so that the whole refrigeration cycle is completed. The dividing wall type cold accumulation heat exchanger is adopted, effective heat exchange of cold and hot fluid in the intermittent flowing state is achieved, the working mode of the dividing wall type cold accumulation heat exchanger is matched with the working mode of the pulse pipe (or piston) expansion machine, the refrigerating efficiency of the system in the intermittent flowing mode is optimized, and therefore the requirement for a refrigerating system with medium-scale refrigerating capacity is met.

Description

Technical Field

[0001] The utility model relates to the technical field of low-temperature refrigeration, in particular to a low-temperature refrigerator. Background Art

[0002] As the world's attention to cryogenic refrigeration technology grows, the development of many emerging technologies and the advancement of large-scale scientific projects rely on the support of cryogenic environments. The demand for medium-scale refrigeration systems at liquid nitrogen, liquid hydrogen and liquid helium temperatures continues to rise. However, pulse tube (or piston) expansion refrigerators suitable for this demand range have the problem of low refrigeration efficiency.

[0003] In a pulse tube (or piston) expansion refrigerator, the performance of the refrigerator is not only closely related to the performance of the expander, but also greatly depends on the performance of the heat exchanger matched with it. Analysis has found that the heat exchange process between the cold and hot fluids in this heat exchanger is significantly different from that of a heat exchanger with continuous and stable flow (for example, a heat exchanger used in a turbine expansion cryogenic refrigerator). The reason for this difference lies in the working mechanism of the pulse tube (or piston) expander, whose expansion and intake process is intermittent and periodic. This working mode causes the flow of cold and hot fluids in the heat exchanger matched with it to be intermittent and periodic, that is, the flow of cold and hot fluids in the heat exchanger does not occur at the same time. Utility Model Content

[0004] In view of this, it is necessary to provide a low-temperature refrigerator with higher refrigeration efficiency to address the technical defects of the current traditional pulse tube (or piston) expansion refrigerators with lower refrigeration efficiency.

[0005] In order to solve the above problems, the utility model adopts the following technical solutions:

[0006] One of the purposes of the utility model is to provide a low-temperature refrigerator, comprising: a compressor, a water cooler, a high-pressure stabilizing tank, a partition-type cold storage heat exchanger, an expander, a cold capacity heat exchanger and a low-pressure stabilizing tank;

[0007] The gaseous working medium at normal temperature and pressure is compressed to a high-pressure state by the compressor, and the compressed gas flows through the water cooler for pre-cooling. The pre-cooled gas enters the high-pressure surge tank and then enters the expander for expansion refrigeration after heat exchange through the partition-type cold storage heat exchanger. The expanded refrigerant is introduced into the cold energy heat exchanger to absorb and utilize the cold energy. The gaseous working medium coming out of the cold energy heat exchanger absorbs heat and heats up through the partition-type cold storage heat exchanger and then returns to the compressor through the low-pressure surge tank to complete the entire refrigeration cycle.

[0008] In some of the embodiments, a bypass valve is further provided between the high-pressure stabilizing tank and the low-pressure stabilizing tank, and the bypass valve is used to adjust the flow rate of the working fluid in the pipeline.

[0009] In some of the embodiments, the expander is a pulse tube expander or a piston expander.

[0010] In some embodiments, the partition-type cold storage heat exchanger includes a heat exchanger core, which includes a metal shell and a plurality of microchannel structures formed in the metal shell, wherein the microchannels are independent of each other, and the microchannels include cold fluid channels and hot fluid channels, and the cold fluid channels and hot fluid channels are arranged in a layered alternating manner.

[0011] In some embodiments, the microchannel includes but is not limited to a matrix or semi-elliptical structure.

[0012] In some embodiments, the microchannels are distributed in an array structure.

[0013] In some embodiments, the cold fluid channels and the hot fluid channels are arranged in alternating layers.

[0014] In some embodiments, the microchannels are straight channels and corrugated channels.

[0015] In some of the embodiments, the microchannel is formed in the metal shell using 3D printing technology.

[0016] In some embodiments, the metal shell includes but is not limited to stainless steel, copper, aluminum and alloys thereof.

[0017] The utility model adopts the above technical solution, and its beneficial effects are as follows:

[0018] In the low-temperature refrigerator provided by the utility model, a gaseous working medium at normal temperature and pressure is compressed to a high-pressure state by the compressor, the compressed gas flows through the water cooler for pre-cooling, the pre-cooled gas enters the high-pressure surge tank and then enters the expander for expansion and refrigeration after heat exchange through the partition-type cold storage heat exchanger, the expanded refrigerant is introduced into the cold capacity heat exchanger to absorb and utilize the cold capacity, the gaseous working medium coming out of the cold capacity heat exchanger absorbs heat and heats up through the partition-type cold storage heat exchanger and then returns to the compressor through the low-pressure surge tank to complete the entire refrigeration cycle. The utility model realizes effective heat exchange between cold and hot fluids in an intermittent flow state by adopting a partition-type cold storage heat exchanger, which cooperates with the working mode of the pulse tube (or piston) expander to optimize the refrigeration efficiency of the system in the intermittent flow mode, thereby meeting the needs of refrigeration systems with medium-sized cold capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments of the utility model or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 This is a schematic structural diagram of a low-temperature refrigerator provided in one embodiment of the utility model.

[0021] Figure 2 A schematic structural diagram of a partition-type cold storage heat exchanger provided in one embodiment of the utility model.

[0022] Figure 3 A schematic diagram of the core structure of a partition-type cold storage heat exchanger provided in one embodiment of the utility model.

[0023] Figure 4 A cross-sectional schematic diagram of the core structure of a partition-type cold storage heat exchanger provided in one embodiment of the utility model. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0025] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "horizontal", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0026] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0028] See also Figure 1 The present invention provides a low-temperature refrigerator, including a compressor 1, a water cooler 2, a high-pressure stabilizing tank 4, a partition-type cold storage heat exchanger 5, an expander 6, a cold heat exchanger 7 and a low-pressure stabilizing tank 8. The specific implementation of each structure is described in detail below.

[0029] The gaseous working medium at normal temperature and pressure is compressed to a high-pressure state by the compressor 1, and the compressed gas flows through the water cooler 2 for pre-cooling. The pre-cooled gas enters the high-pressure surge tank 4 and then enters the expander 6 for expansion and refrigeration after heat exchange through the partition-type cold storage heat exchanger 5. The expanded refrigerant is introduced into the cold energy heat exchanger 7 to absorb and utilize the cold energy. The gaseous working medium coming out of the cold energy heat exchanger 7 absorbs heat and heats up through the partition-type cold storage heat exchanger 5 and then returns to the compressor 1 through the low-pressure surge tank 8 to complete the entire refrigeration cycle.

[0030] Furthermore, a bypass valve 3 is provided between the high-pressure stabilizing tank 4 and the low-pressure stabilizing tank 8 , and the bypass valve 3 is used to adjust the flow rate of the working medium in the pipeline.

[0031] It should be noted that: in the compressor system, the gas working fluid at normal temperature and pressure is compressed to a high-pressure state. Subsequently, the compressed gas flows through the water cooler for pre-cooling, reducing its temperature in preparation for subsequent heat exchange and expansion refrigeration. The bypass valve 3 at the outlet of the compressor 1 is a key component for regulating the flow rate of the system working fluid, allowing the system to adjust the flow rate according to the actual refrigeration demand and optimize the system performance. The high-pressure surge tank 4 and the low-pressure surge tank 8 are used to stabilize the pressure fluctuations of the system in the intermittent flow mode to ensure stable operation of the system. In the refrigeration system, the high-pressure gas first exchanges heat through the interlayer cold storage heat exchanger 5, and then enters the pulse tube (or piston) expander for expansion refrigeration. The pulse tube expander uses pressure waves to achieve rapid expansion of the gas, while the piston expander controls the expansion process through the reciprocating motion of the piston. Both expanders are suitable for small flow conditions. The expanded refrigerant is introduced into the cold heat exchanger to absorb and utilize the cold energy. Finally, the gaseous refrigerant coming out of the cold heat exchanger absorbs heat and heats up through the partition-type cold storage heat exchanger 5, and then returns to the compressor through the low-pressure stabilizing tank 8, completing the entire refrigeration cycle.

[0032] See also Figure 2 , a schematic structural diagram of a partition-type cold storage heat exchanger 5 provided in an embodiment of the utility model includes: a heat exchanger core 100, wherein the heat exchanger core 100 includes a metal shell 110 and a plurality of microchannel structures 120 formed in the metal shell 110. Specifically, the microchannels 120 are independent of each other. The microchannels 120 include cold fluid channels and hot fluid channels, and the cold fluid channels and hot fluid channels are arranged in a layered alternating manner.

[0033] See also Figure 3and Figure 4 , which is a schematic diagram of the structure of the heat exchanger core provided in this embodiment. In this embodiment, the microchannel 120 structure is composed of a number of neatly arranged rectangular microchannels processed on a metal block. The microchannels are independent of each other. The cross section of the heat exchanger is as follows: Figure 3 As shown, the channels marked as "c" represent cold fluid channels, while the channels marked as "h" represent hot fluid channels, and these channels are arranged in a layered alternating manner.

[0034] Furthermore, the heat exchanger core 100 provides two optional types of fluid channel structure design: a straight channel and a corrugated channel. The design of the corrugated channel is intended to further improve the heat exchange efficiency by enhancing the turbulence of the fluid flow.

[0035] It can be understood that the heat exchanger core 100 of the low-temperature refrigerator provided in this embodiment is composed of rectangular microchannels, the microchannels are independent of each other, and the cold runners and hot runners are arranged alternately in layers. According to different application requirements, straight channels or corrugated channel structures can be selected to adapt to different fluid properties and system design requirements.

[0036] Furthermore, the microchannel 120 is formed in the metal shell by 3D printing technology. It can be understood that the microchannel 120 is formed in the metal shell 110 by 3D printing technology, which ensures the accuracy of the flow channel structure and the realization of complex design. It can also select materials with different thermophysical parameters for customized processing as a whole or in sections according to the requirements of different temperature zones of the heat exchanger.

[0037] Furthermore, the metal shell 110 includes but is not limited to stainless steel, copper, aluminum and alloys thereof.

[0038] It should be noted that the selection of materials for the metal shell 110 of the low-temperature refrigerator provided in this embodiment and the design of the structural dimensions need to be based on the operating temperature and pressure range of the heat exchanger, the flow rate of the fluid and the operating frequency of the system, and a metal material with appropriate thermal conductivity, heat capacity and mechanical strength should be selected. In practice, the optional materials include but are not limited to stainless steel, copper, aluminum and its alloys.

[0039] It can be understood that the low-temperature refrigerator provided by the utility model adopts a compact countercurrent heat exchanger design, which effectively increases the heat exchange area and improves the heat transfer efficiency. At the same time, it utilizes the metal wall with a larger heat capacity to store cold or heat, thereby improving the performance of the refrigerator in the intermittent working mode.

[0040] Furthermore, a low-temperature working fluid inlet pipe 111, a normal-temperature working fluid inlet pipe 112, a low-temperature working fluid outlet pipe 113 and a normal-temperature working fluid outlet pipe 114 are provided on the side wall of the metal shell 110. The low-temperature working fluid enters the heat exchanger core 100 through the low-temperature working fluid inlet pipe 111 and flows out through the low-temperature working fluid outlet pipe 113 after heat exchange in the heat exchanger core. The normal-temperature working fluid enters through the normal-temperature working fluid inlet pipe 112 and flows out through the normal-temperature working fluid outlet pipe 114.

[0041] Furthermore, the low-temperature working medium inlet pipe 111 , the normal-temperature working medium inlet pipe 112 , the low-temperature working medium outlet pipe 113 and the normal-temperature working medium outlet pipe 114 are integrally formed on the side wall of the metal shell 110 .

[0042] It can be understood that for applications with large temperature differences between the hot and cold ends, materials with different thermophysical parameters are used for segmented design and processing according to the temperature gradient in the heat exchanger. Thermal matching between segments is achieved by precisely controlling the thermal expansion coefficient and thermal conductivity of the material.

[0043] The utility model realizes effective heat exchange between cold and hot fluids under intermittent flow state by adopting a partition-type cold storage heat exchanger, which cooperates with the working mode of the pulse tube (or piston) expander to optimize the refrigeration efficiency of the system under the intermittent flow mode, thereby meeting the demand for refrigeration systems with medium-sized cooling capacity.

[0044] It can be understood that the technical features of the above-described embodiments can be arbitrarily combined. In order 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.

[0045] The above are only preferred embodiments of the present invention, and only specifically describe the technical principles of the present invention. These descriptions are only for the purpose of explaining the principles of the present invention, and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanation here, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention, and other specific implementation methods of the present invention that can be associated with by technicians in this field without creative labor, should be included in the scope of protection of the present invention.

Claims

1. A low temperature refrigerator, characterized in that: include: Compressor, water cooler, high-pressure stabilizing tank, partition-type cold storage heat exchanger, expander, cold capacity heat exchanger and low-pressure stabilizing tank; The gaseous working medium at normal temperature and pressure is compressed to a high-pressure state by the compressor, and the compressed gas flows through the water cooler for pre-cooling. The pre-cooled gas enters the high-pressure surge tank and then enters the expander for expansion refrigeration after heat exchange through the partition-type cold storage heat exchanger. The expanded refrigerant is introduced into the cold energy heat exchanger to absorb and utilize the cold energy. The gaseous working medium coming out of the cold energy heat exchanger absorbs heat and heats up through the partition-type cold storage heat exchanger and then returns to the compressor through the low-pressure surge tank to complete the entire refrigeration cycle.

2. The cryogenic refrigerator according to claim 1, characterized in that: A bypass valve is also provided between the high-pressure stabilizing tank and the low-pressure stabilizing tank, and the bypass valve is used to adjust the flow rate of the working medium in the pipeline.

3. The cryogenic refrigerator according to claim 1, characterized in that: The expander is a pulse tube expander or a piston expander.

4. The cryogenic refrigerator according to claim 1, characterized in that: The partition-type cold storage heat exchanger includes a heat exchanger core, which includes a metal shell and a plurality of microchannel structures formed in the metal shell. The microchannels are independent of each other. The microchannels include cold fluid channels and hot fluid channels, and the cold fluid channels and hot fluid channels are arranged in a layered alternating manner.

5. The cryogenic refrigerator according to claim 4, characterized in that: The microchannels include, but are not limited to, matrix or semi-elliptical structures.

6. The cryogenic refrigerator according to claim 4, characterized in that: The microchannels are distributed in an array structure.

7. The cryogenic refrigerator according to claim 4, characterized in that: The cold fluid channels and the hot fluid channels are arranged in a layered alternating manner.

8. The cryogenic refrigerator according to claim 4, characterized in that: The microchannels are straight channels and corrugated channels.

9. The cryogenic refrigerator according to claim 4, characterized in that: The microchannel is formed in the metal shell by using 3D printing technology.

10. The cryogenic refrigerator according to claim 4, characterized in that: The metal shell includes but is not limited to stainless steel, copper, aluminum and alloys thereof.

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