Ultralow-temperature refrigerating system for refrigeration house

Abstract

The utility model belongs to the technical field of ultralow-temperature refrigeration, and particularly relates to an ultralow-temperature refrigeration system for a refrigeration house, which comprises a first refrigeration system, a second refrigeration system and a heat exchanger, the first refrigerant circularly flows in the first refrigerating system; the second refrigerating system comprises a second compressor, a second oil-gas separator and an evaporator which are sequentially connected end to end, and further comprises a second refrigerant which circularly flows in the second refrigerating system; the evaporator is located in the refrigeration house to cool the refrigeration house. Compared with the prior art, through the arrangement of the second refrigerating system, the technical problem that in the prior art, the temperature of the refrigeration house cannot be lowered to the ultralow temperature state is solved.

Description

Technical Field

[0001] This utility model belongs to the field of ultra-low temperature refrigeration technology, and specifically relates to an ultra-low temperature refrigeration system for cold storage. Background Technology

[0002] With the rapid development of modern cold chain logistics, biomedicine, food processing, and other industries, cold storage facilities, as essential facilities for storing temperature-sensitive items, are finding increasingly wider applications. In the biomedical field, ultra-low temperature cold storage is commonly used to store biological samples such as vaccines, stem cells, and blood products. In the food processing industry, ultra-low temperature freezing helps to better preserve the nutritional components and taste of food. These scenarios place stringent requirements on the ultra-low temperature freezing performance of cold storage facilities, typically requiring internal temperatures to reach below -70°C.

[0003] However, most existing refrigeration systems adopt a single-stage refrigeration cycle structure. Due to limitations such as refrigerant characteristics and compression ratio, the refrigeration capacity of a single-stage refrigeration system is limited, and its refrigeration temperature can usually only reach above -30℃, which is difficult to meet the requirements of ultra-low temperature cold storage for extremely low temperature environments below -70℃.

[0004] Meanwhile, during the operation of the refrigeration system, the lubricating oil in the compressor circulates with the refrigerant. Even after purification by the oil-gas separator, a small amount of oil mist will still enter the evaporator. Due to the low temperature inside the evaporator, the lubricating oil becomes more viscous in the low-temperature environment, easily adhering to the evaporator tube wall. This severely affects the heat exchange efficiency between the refrigerant and the cold storage environment, leading to a decrease in refrigeration effect and increasing the frequency of refrigeration system maintenance and costs.

[0005] Therefore, how to overcome the temperature limitations of single-stage refrigeration systems and design a refrigeration system that can achieve ultra-low temperature refrigeration while effectively reducing oil mist adhesion in the evaporator has become an urgent technical problem to be solved. Utility Model Content

[0006] This utility model aims to provide an ultra-low temperature refrigeration system for cold storage, mainly to solve the technical problem that most existing refrigeration systems adopt a single-stage refrigeration cycle structure. Due to limitations such as refrigerant characteristics and compression ratio, the refrigeration capacity of a single-stage refrigeration system is limited, and its refrigeration temperature can usually only reach above -30℃, which is difficult to meet the technical requirements of ultra-low temperature cold storage for extremely low temperature environments below -70℃.

[0007] To solve the above-mentioned technical problems, this utility model provides the following technical solution:

[0008] An ultra-low temperature refrigeration system for cold storage includes a first refrigeration system, a second refrigeration system, and a heat exchanger;

[0009] The first refrigeration system includes a first compressor, a first oil-gas separator, and a first condenser connected in sequence from end to end, and also includes a first refrigerant circulating in the first refrigeration system;

[0010] The second refrigeration system includes a second compressor, a second oil-gas separator, and an evaporator connected in sequence from end to end, and also includes a second refrigerant circulating in the second refrigeration system;

[0011] The evaporator is located in the cold storage to cool the cold storage;

[0012] The heat exchanger includes a first heat exchange channel and a second heat exchange channel;

[0013] One end of the first heat exchange channel is connected to the first condenser, and the other end is connected to the first compressor, which expands the condensed first refrigerant into a gaseous state;

[0014] One end of the second heat exchange channel is connected to the evaporator, and the other end is connected to the second oil-gas separator, which condenses the gaseous second refrigerant into a liquid state.

[0015] Preferably, the second refrigeration system further includes an oil mist capture device, which includes a housing that is sealed and connected to the second condenser and the evaporator at both ends, respectively, and a mist trapping net for intercepting oil mist is provided inside the housing.

[0016] Preferably, the evaporator includes an air inlet pipe, the housing is cylindrical, and the ratio of the inner diameter of the housing to the inner diameter of the air inlet pipe is 1:0.7 to 0.8.

[0017] Preferably, the mist trap is made of several metal strips woven together, and the mist trap has several mesh openings for gas to pass through.

[0018] Preferably, a first control valve communicating with the interior of the housing is provided below the housing, and a collection box is provided at the output end of the first control valve, with a second control valve provided at the bottom of the collection box.

[0019] Preferably, the edge of the foam trap is fixed to the inner wall of the shell, and the angle between the central axis of the foam trap and the central axis of the shell is between 30° and 90°.

[0020] Preferably, the metal strip includes a first metal wire, and a second metal wire is wound around the outer periphery of the first metal wire.

[0021] The beneficial effects of this utility model are as follows:

[0022] (1) This scheme uses a two-stage refrigeration system to cool the second refrigerant in the second-stage refrigeration system, so that after evaporation in the evaporator, the temperature inside the cold storage can be reduced to below -70℃, which breaks through the defect of a single-stage refrigeration system that can only reduce the room temperature to above -30℃, and realizes ultra-low temperature refrigeration.

[0023] (2) During the second refrigerant circulation process, the lubricating oil in the second compressor is easily carried away and enters the evaporator. Because the temperature in the evaporator is low, the lubricating oil becomes more viscous in the low temperature environment. Although it is purified by the second oil-gas separator, a small amount of oil mist will still enter the evaporator with the second refrigerant and stick to the evaporator tube wall, affecting the heat exchange between the refrigerant and the cold storage environment. By setting an oil mist capture device to filter the gaseous second refrigerant entering the evaporator, the amount of oil mist entering the evaporator is reduced, the oil mist adhesion in the evaporator is alleviated, and the maintenance rate of the second refrigeration system is reduced.

[0024] (3) The gaseous second refrigerant passes through the condensate screen, breaking the gas-liquid balance in the mixture, so that the oil droplets carried in the gas are intercepted by the condensate screen and slide down the metal strip to the bottom of the shell, thus purifying the gas entering the evaporator.

[0025] (4) The second metal wire is wrapped around the surface of the first metal wire, making the surface of the metal strip rough, increasing the contact area with the airflow, and the intercepted oil droplets are blocked by the gap formed by the second metal wire, making it difficult for them to re-enter the evaporator with the gas. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0027] Figure 1 This is a flowchart illustrating the operation of an ultra-low temperature refrigeration system for cold storage, as per this utility model patent.

[0028] Figure 2 This is a three-dimensional structural diagram of an oil mist capture device for an ultra-low temperature refrigeration system for cold storage, as per this utility model patent.

[0029] Figure 3 This utility model patent discloses an ultra-low temperature refrigeration system for cold storage. Figure 3 A three-dimensional cross-sectional view;

[0030] Figure 4 This is a three-dimensional structural diagram of a metal strip in an ultra-low temperature refrigeration system for cold storage, as per this utility model patent.

[0031] The reference numerals in the accompanying drawings include: second condenser 1, evaporator 2, shell 31, condensate screen 32, first control valve 33, collection box 34, second control valve 35, second expansion valve 4, first metal wire 51, and second metal wire 52. Detailed Implementation

[0032] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0033] In the description of this utility model, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "top surface", "bottom surface", "inner", "outer", "inner side", "outer side", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0034] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If the terms "first," "second," and "third" are used in the description, they are for descriptive purposes and to distinguish technical features, and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the sequential relationship of the indicated technical features.

[0035] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances. The embodiments of this utility model will now be described based on its overall structure.

[0036] like Figure 1 As shown, an ultra-low temperature refrigeration system for cold storage is disclosed. This ultra-low temperature refrigeration system for cold storage consists of a first refrigeration system, a second refrigeration system, and a heat exchanger. The first refrigeration system provides initial refrigeration and supports the cooling capacity of the second refrigeration system, while the second refrigeration system directly cools the cold storage. The heat exchanger facilitates heat exchange between the two refrigeration systems to achieve ultra-low temperature refrigeration.

[0037] The first refrigeration system includes a first compressor, a first oil-gas separator, a first condenser, a first liquid receiver, a first expansion valve, and a heat exchanger, connected sequentially from end to end, as well as a first refrigerant circulating in the system. The discharge port of the first compressor is sealed to the inlet of the first oil-gas separator. The first compressor compresses the first refrigerant, increasing its pressure and temperature, transforming the low-temperature, low-pressure gaseous refrigerant into a high-temperature, high-pressure gaseous state. The outlet of the first oil-gas separator is sealed to the inlet of the first condenser via a pipe. The first oil-gas separator separates lubricating oil carried in the first refrigerant, preventing it from entering the first condenser and affecting heat exchange efficiency. The condensed liquid first refrigerant from the first condenser is temporarily stored in the first liquid receiver and then slowly enters the heat exchanger through a throttling valve.

[0038] The outlet of the first condenser is connected to one end of the first heat exchange channel of the heat exchanger via a pipe and the first expansion valve (the heat exchanger is existing technology, and regardless of the type of heat exchanger, it usually includes two heat exchange channels, which are not specifically limited here). The other end of the first heat exchange channel is connected to the inlet of the first compressor. The first heat exchange channel can expand the condensed liquid first refrigerant, turning it into a gaseous state, and return it to the first compressor for the next cycle.

[0039] The second refrigeration system includes a second compressor, a second oil-gas separator, a second liquid storage tank, a second expansion valve, and an evaporator 2 connected sequentially, along with a second refrigerant circulating within the system. The exhaust port of the second compressor is sealed to the inlet of the second oil-gas separator. The second compressor compresses the second refrigerant, increasing its pressure and temperature. The outlet of the second oil-gas separator is sealed to one end of the second heat exchange channel of the heat exchanger via a pipe. The second oil-gas separator separates most of the lubricating oil carried in the second refrigerant. One end of the second heat exchange channel of the heat exchanger is connected to the outlet of the second oil-gas separator, and the other end is connected to the second liquid storage tank, storing the condensed liquid second refrigerant. The outlet of the second liquid storage tank is equipped with a second expansion valve 4, the outlet of which is connected to the inlet of the evaporator 2. The evaporator 2, located inside the cold storage, expands the liquid second refrigerant into a gaseous state through the second expansion valve. The evaporation of the second refrigerant absorbs heat from the cold storage, thus cooling it. The outlet of evaporator 2 is connected to the inlet of the second compressor through a pipe to realize the circulation of the second refrigerant.

[0040] This solution uses a two-stage refrigeration system to cool the second refrigerant in the second-stage refrigeration system, allowing it to evaporate in the evaporator and lower the temperature inside the cold storage to below -70℃. This overcomes the limitation of single-stage refrigeration systems, which can only lower the room temperature to above -30℃, and achieves ultra-low temperature refrigeration.

[0041] Example 2:

[0042] like Figures 2-4 As shown, an oil mist capture device is also provided in the second refrigeration system. The oil mist capture device includes a housing 31, with both ends of the housing 31 connected to the second condenser 1 and the evaporator 2 respectively via pipes. A second expansion valve 4 is located between the housing 31 and the second condenser 1 to expand the liquid second refrigerant into a gaseous second refrigerant. A mist trap 32 for intercepting oil droplets is installed inside the housing 31. Specifically, the housing 31 is cylindrical, and its inner diameter is 1:0.7-0.8 of the inner diameter of the evaporator 2's inlet pipe. This size design allows for suitable gas flow velocity and pressure within the housing 31, facilitating oil mist capture. Furthermore, due to the slight difference in pipe diameters, the connection point forms an angle, allowing oil droplets in the gas to be intercepted together.

[0043] like Figure 4 As shown, the mist trap 32 has several mesh openings for gas passage. The gaseous second refrigerant can pass through these meshes, while oil droplets are intercepted by the mist trap 32. The edge of the mist trap 32 is fixed to the inner wall of the housing 31, and the angle between the central axis of the mist trap 32 and the central axis of the housing 31 is between 30° and 90°. This angle setting facilitates the disruption of the gas-liquid balance in the mixture when the gaseous second refrigerant passes through the mist trap 32, causing oil droplets carried in the gas to be intercepted by the mist trap 32 and slide down the metal strips to the bottom of the housing 31. The mist trap 32 is composed of several interwoven metal strips, each including a first metal wire 51. A second metal wire 52 is wound around the outer periphery of the first metal wire 51. This structure makes the surface of the metal strips rough, increasing the contact area with the airflow. Simultaneously, the intercepted oil droplets are blocked by the gaps formed by the winding of the second metal wire 52, making it difficult for them to re-enter the evaporator 2 with the gas.

[0044] A first control valve 33, communicating with the interior of the housing 31, is located below the housing 31. A collection tank 34 is connected to the output of the first control valve 33. The first control valve 33 is normally open, and the lubricating oil collected by the slurry screen 32 passes through the first control valve 33 into the collection tank 34. A second control valve 35 is located at the bottom of the collection tank 34. When a certain amount of oil accumulates in the collection tank 34, the first control valve 33 is closed, sealing the interior of the housing 31. Then, the second control valve 35 is opened to drain the oil from the collection tank 34. The second control valve 35 is then closed again, and the first control valve 33 is opened, allowing the lubricating oil inside the housing 31 to continue dripping into the collection tank 34.

[0045] In actual operation, the first refrigeration system operates, and the first refrigerant circulates within the system. After being compressed by the first compressor, separated by the first oil-gas separator, and condensed by the first condenser, it expands into a gaseous state through the first heat exchange channel of the heat exchanger and returns to the first compressor. Simultaneously, the second refrigeration system operates. The second refrigerant is compressed by the second compressor and enters the second oil-gas separator, where most of the lubricating oil is separated. The gaseous second refrigerant enters the second heat exchange channel of the heat exchanger and is cooled and condensed into a liquid state by the cooling capacity of the first refrigeration system. The liquid second refrigerant then passes through the second expansion valve 4 to become a gaseous second refrigerant, which then passes through the casing 31 to remove oil droplets from the gas and liquid phases. It then enters the evaporator 2 to evaporate and absorb heat, cooling the cold storage. After exiting the evaporator 2, the gaseous second refrigerant enters the second compressor to begin the next cycle. Through the coordinated operation of the two-stage refrigeration system, the temperature inside the cold storage can be reduced to below -70℃. Furthermore, the oil mist capture device reduces oil mist adhesion within the evaporator 2, lowering the maintenance rate of the second refrigeration system.

[0046] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the present invention to the precise forms disclosed, and it is obvious that many changes and variations can be made based on the above teachings. Although embodiments of the present invention have been shown and described, these specific embodiments are merely explanations of the present invention and are not intended to limit the invention. The specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. The purpose of selecting and describing exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art, after reading this specification, can make modifications, substitutions, variations, and various choices and changes to the embodiments as needed without departing from the principles and spirit of the present invention, provided that such modifications, substitutions, variations, and choices and changes are within the scope of the claims of the present invention and are protected by patent law.

Claims

1. A cryogenic refrigeration system for cold storage, characterized in that, It includes a first refrigeration system, a second refrigeration system, and a heat exchanger. The first refrigeration system includes a first compressor, a first oil-gas separator, and a first condenser connected in sequence from end to end, and also includes a first refrigerant circulating in the first refrigeration system. The second refrigeration system includes a second compressor, a second oil-gas separator, and an evaporator connected in sequence from end to end, and also includes a second refrigerant circulating in the second refrigeration system; The evaporator is located in the cold storage to cool the cold storage; The heat exchanger includes a first heat exchange channel and a second heat exchange channel; One end of the first heat exchange channel is connected to the first condenser, and the other end is connected to the first compressor, which expands the condensed first refrigerant into a gaseous state; One end of the second heat exchange channel is connected to the evaporator, and the other end is connected to the second oil-gas separator, which condenses the gaseous second refrigerant into a liquid state.

2. The ultra-low temperature refrigeration system for cold storage according to claim 1, characterized in that, The second refrigeration system also includes an oil mist capture device, which includes a housing that is sealed and connected to the second condenser and the evaporator at both ends, respectively, and a mist trapping net for intercepting oil mist is provided inside the housing.

3. The ultra-low temperature refrigeration system for cold storage according to claim 2, characterized in that, The evaporator includes an air inlet pipe, the housing is cylindrical, and the ratio of the inner diameter of the housing to the inner diameter of the air inlet pipe is 1:0.7 to 0.

8.

4. The ultra-low temperature refrigeration system for cold storage according to claim 3, characterized in that, The mist trap is made of several metal strips woven together, and the mist trap has several mesh openings for gas to pass through.

5. The ultra-low temperature refrigeration system for cold storage according to claim 4, characterized in that, A first control valve communicating with the interior of the housing is provided below the housing. A collection box is connected to the output end of the first control valve, and a second control valve is provided at the bottom of the collection box.

6. The ultra-low temperature refrigeration system for cold storage according to claim 5, characterized in that, The edge of the mist trap is fixed to the inner wall of the shell, and the angle between the central axis of the mist trap and the central axis of the shell is between 30° and 90°.

7. The ultra-low temperature refrigeration system for cold storage according to claim 6, characterized in that, The metal strip includes a first metal wire, and a second metal wire is wound around the outer periphery of the first metal wire.

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