Low-temperature heat exchanger

Abstract

The invention discloses a low-temperature heat exchanger, and relates to the technical field of refrigeration equipment, the low-temperature heat exchanger comprises a slit heat exchanger, an air inlet joint, an air outlet joint and a sealing shell, the top end and the bottom end of the slit heat exchanger are respectively connected with the air inlet joint and the air outlet joint, and the sealing shell is arranged outside the slit heat exchanger; a sealing cavity capable of containing a heat transfer medium is formed between the sealing shell and the slit heat exchanger, and the sealing shell is provided with an inflation pipe used for filling the sealing cavity with the heat transfer medium. The sealing shell is arranged outside the wall surface of the slit heat exchanger, and the formed cavity is filled with the heat transfer medium with proper pressure. When the temperature of the cold end is lower than the critical temperature of the heat transfer medium, the heat transfer medium is liquefied and flows downwards under the action of gravity, and the liquefied heat transfer medium flows upwards after being heated and gasified by the wall surface of the lower end, so that two-phase heat exchange circulation is formed, the wall surface temperature difference of the slit heat exchanger is remarkably reduced, and the purpose of improving the heat exchange efficiency is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration equipment, and in particular to a low-temperature heat exchanger. Background Art

[0002] In the field of low-temperature refrigeration, it is necessary to pre-cool the circulating gas working medium. Usually, a low-temperature cold source (such as another refrigerator in the temperature zone) provides the cooling required for cooling. In order to reduce the thermal resistance of thermal conductivity, the cold head of the cold source is usually made of copper. The gas working medium flows through the wall of the cold head, so that it can be convectively exchanged with the cold head to achieve the purpose of pre-cooling and cooling. However, in order to increase the heat exchange area and improve the heat exchange efficiency, a slit heat exchanger is usually processed. The gas flows through the small flow channel in the slit and conducts convective heat exchange with the wall of the slit heat exchanger. The wall of the slit heat exchanger is then in thermal contact with the cold head of the low-temperature cold source to achieve heat conduction heat exchange. Therefore, the existing common low-temperature heat exchanger structure usually consists of an air inlet, a slit heat exchanger, and an air outlet. The gas working medium that needs to be pre-cooled enters the slit heat exchanger from the air inlet. The slit can expand the heat exchange area to achieve efficient heat exchange between the gas working medium and the wall of the heat exchanger. The wall of the slit heat exchanger is generally directly connected to the cold source to ensure the low temperature of the wall. The pre-cooled gaseous working medium then flows out from the gas outlet.

[0003] After the gas working medium flows through the wall of the slot heat exchanger, the temperature of the slot heat exchanger wall will increase, so the slot heat exchanger is usually arranged horizontally with the cold head. In this way, the wall of the slot heat exchanger can exchange heat with the low-temperature cold source along the axial direction. In the case of limited horizontal space, the pre-cooling heat exchanger needs to be arranged vertically, which means that only the upper part of the slot heat exchanger can directly contact the cold source, resulting in an increase in the temperature of the lower slot heat exchanger wall away from the cold source, thereby affecting the heat exchange efficiency.

[0004] In summary, the existing low-temperature heat exchangers are designed with a long axial scale to increase the heat exchange area and are required to be placed vertically to reduce the radial space occupied. However, due to the existence of thermal resistance of the solid wall and its increase with the increase of axial length, the temperature of the wall away from the cold end increases, thereby reducing the low-temperature heat exchange efficiency. Summary of the invention

[0005] The object of the present invention is to provide a low-temperature heat exchanger to solve the problems existing in the above-mentioned prior art, and to reduce the wall temperature difference between the upper and lower parts of the slit heat exchanger to achieve the purpose of improving the heat exchange efficiency.

[0006] To achieve the above object, the present invention provides the following solutions: The present invention provides a low-temperature heat exchanger, comprising a slit heat exchanger, an air inlet joint, an air outlet joint and a sealed shell, wherein the top and bottom ends of the slit heat exchanger are respectively connected to the air inlet joint and the air outlet joint, the sealed shell is arranged outside the slit heat exchanger, a sealed cavity capable of accommodating a heat transfer medium is formed between the sealed shell and the slit heat exchanger, and an inflation pipe for injecting the heat transfer medium into the sealed cavity is arranged on the sealed shell.

[0007] Preferably, the top and bottom ends of the slit heat exchanger are respectively integrally provided with a top connecting plate and a bottom connecting plate, the two ends of the sealed shell are respectively connected to the top connecting plate and the bottom connecting plate, and the slit heat exchanger contacts the low-temperature cold source through the upper end surface of the top connecting plate.

[0008] Preferably, the air inlet joint is fixed to the top connecting plate via a connecting flange, and the air outlet joint is welded into the center hole of the bottom connecting plate.

[0009] Preferably, the air inlet joint is connected to the connecting flange by screws, and the connecting flange is welded to the top connecting plate.

[0010] Preferably, the air inlet channel of the air inlet joint, the central channel of the slit heat exchanger and the air outlet channel of the air outlet joint are concentric channels.

[0011] Preferably, a flow guide and an impurity adsorber are provided at the medium inlet at the top end of the central channel of the slit heat exchanger, and the flow guide is provided at the top of the impurity adsorber.

[0012] Preferably, the slot heat exchanger and the sealed shell are both made of oxygen-free copper.

[0013] Preferably, the inflation tube is a copper tube and is fixed to the sealing shell by welding.

[0014] Preferably, the air inlet connector, the air outlet connector and the connecting flange are all made of stainless steel.

[0015] Compared with the prior art, the present invention has achieved the following technical effects: The low-temperature heat exchanger in the present invention is provided with a sealed shell outside the wall of the slit heat exchanger, and the formed cavity is filled with a heat transfer medium of suitable pressure. When the temperature of the cold end is lower than the critical temperature of the heat transfer medium, the heat transfer medium will liquefy and flow downward under the action of gravity, and the liquefied heat transfer medium will vaporize under the heating of the wall at the lower end and flow upward, thus forming a two-phase heat exchange cycle, significantly reducing the wall temperature difference of the slit heat exchanger, and achieving the purpose of improving the heat exchange efficiency; the two-phase heat exchange cycle similar to the gravity heat pipe adopted by the present invention improves the heat exchange efficiency compared with simple heat conduction, reduces the volume weight of the heat exchanger, and can better reduce the wall temperature.

[0016] Furthermore, by arranging a deflector after the air inlet, the turbulence caused by the significant change in the flow channel diameter can be effectively reduced, and the flow resistance loss during the flow process can be reduced. At the same time, the deflector can also serve as a fixer for the porous material in the impurity adsorber to prevent the porous granular material from leaking out of the air inlet. The surface of the porous medium in the arranged impurity adsorber can adsorb impurity gases at low temperatures. The slit heat exchanger arranged lastly is precooled to a suitable temperature through convective heat exchange between the wall and the gas working medium. The arrangement of the present invention integrates the functions of flow stabilization, impurity removal and precooling heat exchange, making the structure compact. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the three-dimensional structure of the low-temperature heat exchanger of the present invention; Figure 2 is a cross-sectional view of a low-temperature heat exchanger of the present invention; Figure 3 It is a schematic diagram of the three-dimensional structure of the slit heat exchanger in the present invention; In the figure: 1. Air inlet connector; 2. Connecting flange; 3. Flow guide; 4. Impurity adsorber; 5. Slit heat exchanger; 6. Sealed housing; 7. Heat transfer medium; 8. Filling pipe; 9. Air outlet connector. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The purpose of the present invention is to provide a low-temperature heat exchanger to solve the problems existing in the prior art. A sealed shell is arranged outside the wall of the slot heat exchanger, and a heat transfer medium with a suitable pressure is filled in the formed cavity. When the temperature at the cold end is lower than the critical temperature of the heat transfer medium, the heat transfer medium will liquefy and flow downward under the action of gravity. The liquefied heat transfer medium will vaporize under the heating of the wall at the lower end and flow upward, thereby forming a two-phase heat exchange cycle, significantly reducing the wall temperature difference of the slot heat exchanger, and achieving the purpose of improving the heat exchange efficiency.

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] The low temperature heat exchanger in this embodiment, such as Figure 1-Figure 3 As shown, it includes a slit heat exchanger 5, an air inlet joint 1, an air outlet joint 9 and a sealed shell 6. The top and bottom ends of the slit heat exchanger 5 are respectively connected to the air inlet joint 1 and the air outlet joint 9. The sealed shell 6 is arranged outside the slit heat exchanger 5. A sealed cavity capable of accommodating a heat transfer medium 7 is formed between the sealed shell 6 and the slit heat exchanger 5. The sealed shell 6 is provided with an inflation pipe 8 for injecting the heat transfer medium 7 into the sealed cavity.

[0023] In this specific embodiment, the top and bottom ends of the slit heat exchanger 5 are respectively integrally provided with a top connecting plate and a bottom connecting plate, and the two ends of the sealing shell 6 are respectively welded to the top connecting plate and the bottom connecting plate to achieve sealing, and the slit heat exchanger 5 contacts the low-temperature cold source through the upper end surface of the top connecting plate.

[0024] In this specific embodiment, the air inlet connector 1 is fixed to the top connecting plate via the connecting flange 2, and the air outlet connector 9 is welded to the center hole of the bottom connecting plate. The air inlet connector 1, the air outlet connector 9 and the connecting flange 2 are all made of stainless steel.

[0025] In this specific embodiment, the air inlet connector 1 is connected to the connecting flange 2 by screws, and the connecting flange 2 is welded to the top connecting plate. A groove is provided in the connecting flange 2 for installing a metal gasket as a sealing material to achieve a sealed connection with the air inlet connector 1.

[0026] In this specific embodiment, the air inlet channel of the air inlet connector 1, the central channel of the slit heat exchanger 5 and the air outlet channel of the air outlet connector 9 are concentric channels.

[0027] In this specific embodiment, a flow guide 3 and an impurity adsorber 4 are provided at the medium inlet at the top of the central channel of the slit heat exchanger 5, and the flow guide 3 is provided at the top of the impurity adsorber 4. The flow guide 3 is filled with a stainless steel wire mesh or made of a porous stainless steel plate. The impurity adsorber 4 is usually porous activated carbon.

[0028] In this specific embodiment, the slit heat exchanger 5 and the sealed shell 6 are both made of oxygen-free copper, and the slit heat exchanger 5 has a plurality of slits cut therein.

[0029] In this specific embodiment, the inflation tube 8 is a copper tube and is welded and fixed to the sealed shell 6. The heat transfer medium 7 is filled into the sealed cavity composed of the seam heat exchanger body and the sealed shell 6 through the inflation tube 8. When it is filled to a suitable pressure, the inflation tube 8 is clamped to achieve sealing.

[0030] During operation, the upper end of the slit heat exchanger 5 is connected to a cold source. The gas working medium that needs to be cooled to a low temperature enters the deflector 3 vertically from the air inlet joint 1. The deflector 3 is used to stabilize the flow and reduce the turbulence of the gas working medium during the process of changing the diameter of the pipeline. After passing through the deflector 3, the gas working medium enters the impurity adsorber 4. The porous material in the impurity adsorber 4 can adsorb gas impurities other than the gas working medium at low temperatures. After passing through the impurity adsorber 4, the gas working medium enters the slit heat exchanger 5, and fully contacts with the low-temperature wall through multiple slits to achieve pre-cooling and heat exchange. After gradually pre-cooling to a suitable low-temperature temperature, it flows out through the outlet joint 9. The heat transfer medium 7 between the slit heat exchanger 5 and the sealed shell 6 is liquefied and condensed near the low-temperature cold source end, flows downward under gravity, and absorbs heat near the wall of the slit heat exchanger 5 at the lower end and then vaporizes upward, thereby realizing a two-phase countercurrent heat exchange cycle, reducing the axial (vertical) wall temperature difference of the slit heat exchanger 5, and improving the heat exchange efficiency.

[0031] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A low temperature heat exchanger, Features: The invention comprises a slit heat exchanger, an air inlet joint, an air outlet joint and a sealed shell. The top and bottom ends of the slit heat exchanger are respectively connected to the air inlet joint and the air outlet joint. The sealed shell is arranged outside the slit heat exchanger. A sealed cavity capable of accommodating a heat transfer medium is formed between the sealed shell and the slit heat exchanger. The sealed shell is provided with an inflation pipe for injecting the heat transfer medium into the sealed cavity.

2. The low-temperature heat exchanger according to claim 1, Features: The top and bottom ends of the slit heat exchanger are respectively integrally provided with a top connecting plate and a bottom connecting plate, the two ends of the sealed shell are respectively connected to the top connecting plate and the bottom connecting plate, and the slit heat exchanger contacts the low-temperature cold source through the upper end surface of the top connecting plate.

3. The low temperature heat exchanger according to claim 2, Features: The air inlet joint is fixed to the top connecting plate through a connecting flange, and the air outlet joint is welded in the central hole of the bottom connecting plate.

4. The low-temperature heat exchanger according to claim 3, Features: The air inlet joint is connected to the connecting flange by screws, and the connecting flange is welded to the top connecting plate.

5. The low temperature heat exchanger according to claim 1, Features: The air inlet channel of the air inlet joint, the central channel of the slit heat exchanger and the air outlet channel of the air outlet joint are concentric channels.

6. The low temperature heat exchanger according to claim 1, Features: A flow guide and an impurity adsorber are arranged at the medium inlet at the top end of the central channel of the slit heat exchanger, and the flow guide is arranged at the top of the impurity adsorber.

7. The low-temperature heat exchanger according to claim 1, Features: The slit heat exchanger and the sealed shell are both made of oxygen-free copper.

8. The low-temperature heat exchanger according to claim 1, Features: The inflation tube is a copper tube and is welded and fixed to the sealing shell.

9. The low-temperature heat exchanger according to claim 3, Features: The air inlet joint, the air outlet joint and the connecting flange are all made of stainless steel.

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