A low-temperature heat exchanger

Abstract

This invention discloses a low-temperature heat exchanger, relating to the field of refrigeration equipment technology. It includes a slit heat exchanger, an inlet connector, an outlet connector, and a sealed outer shell. The top and bottom ends of the slit heat exchanger are connected to the inlet connector and outlet connector, respectively. A sealed outer shell is provided outside the slit heat exchanger, forming a sealed cavity between the sealed outer shell and the slit heat exchanger capable of containing the heat transfer medium. An air filling pipe for filling the sealed cavity with the heat transfer medium is provided on the sealed outer shell. This invention sets a sealed outer shell outside the wall of the slit heat exchanger and fills the formed cavity with a heat transfer medium at a suitable pressure. When the cold end temperature is lower than the critical temperature of the heat transfer medium, the heat transfer medium liquefies and flows downwards under gravity. The liquefied heat transfer medium vaporizes under the heating of the lower wall and flows upwards, thus forming a two-phase heat exchange cycle. This significantly reduces the wall temperature difference of the slit heat exchanger, achieving the purpose of improving heat exchange efficiency.

Description

Technical Field

[0001] This invention relates to the field of refrigeration equipment technology, and in particular to a low-temperature heat exchanger. Background Technology

[0002] In cryogenic refrigeration, pre-cooling of the circulating gaseous working fluid is necessary. This is typically achieved by a cryogenic cold source (such as another refrigeration unit operating in the same temperature range). To reduce thermal resistance, the cold head of this cold source is usually made of copper. Passing the gaseous working fluid through the wall of the cold head allows for convective heat exchange, achieving pre-cooling. However, to increase the heat exchange area and improve efficiency, a slit heat exchanger is often fabricated. The gas flows through a narrow channel within the slit, convecting with the wall of the slit heat exchanger. The slit heat exchanger wall then comes into thermal contact with the cold head of the cryogenic cold source, achieving conductive heat exchange. Therefore, common cryogenic heat exchanger structures typically consist of an inlet, a slit heat exchanger, and an outlet. The gaseous working fluid requiring pre-cooling enters the slit heat exchanger through the inlet. The slit expands the heat exchange area, enabling efficient heat exchange between the gaseous working fluid and the heat exchanger wall. The wall of the slit heat exchanger is generally directly connected to the cold source, ensuring a low wall temperature. The pre-cooled working gas then flows out from the outlet.

[0003] When the gaseous working fluid flows through the wall of a slot heat exchanger, the temperature of the wall rises. Therefore, slot heat exchangers are usually arranged horizontally with the cold head. This ensures that the wall of the slot heat exchanger can exchange heat with the low-temperature cold source along the axial direction. However, when horizontal space is limited and the pre-cooling heat exchanger needs to be arranged vertically, only the upper part of the slot heat exchanger can directly contact the cold source. This results in the lower part of the slot heat exchanger wall, farther from the cold source, experiencing a temperature increase, thus affecting heat exchange efficiency.

[0004] In summary, existing low-temperature heat exchangers, designed with a long axial dimension to increase the heat exchange area and requiring vertical placement to reduce radial space occupation, suffer from reduced low-temperature heat exchange efficiency due to the presence of thermal resistance on the solid wall surface, which increases with the axial length. This leads to an increase in wall temperature away from the cold end. Summary of the Invention

[0005] The purpose of this invention is to provide a low-temperature heat exchanger to solve the problems existing in the prior art, thereby reducing the temperature difference between the upper and lower walls of the slit heat exchanger and improving the heat exchange efficiency.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] The present invention provides a low-temperature heat exchanger, comprising a slit heat exchanger, an inlet connector, an outlet connector, and a sealed outer shell. The top and bottom ends of the slit heat exchanger are respectively connected to the inlet connector and the outlet connector. The sealed outer shell is disposed outside the slit heat exchanger, and a sealed cavity capable of accommodating a heat transfer medium is formed between the sealed outer shell and the slit heat exchanger. An air filling pipe for filling the heat transfer medium into the sealed cavity is provided on the sealed outer shell.

[0008] Preferably, the top and bottom ends of the slit heat exchanger are integrally provided with a top connecting plate and a bottom connecting plate, respectively, and the two ends of the sealed shell are connected to the top connecting plate and the bottom connecting plate, respectively. The slit heat exchanger contacts the low-temperature cold source through the upper end surface of the top connecting plate.

[0009] Preferably, the air inlet connector is fixed to the top connecting plate via a connecting flange, and the air outlet connector is welded to the center hole of the bottom connecting plate.

[0010] Preferably, the air intake connector is connected to the connecting flange by screws, and the connecting flange is welded to the top connecting plate.

[0011] Preferably, the air inlet channel of the air inlet connector, the central channel of the slit heat exchanger, and the air outlet channel of the air outlet connector are concentric channels.

[0012] Preferably, a flow guide and an impurity adsorber are provided at the medium inlet at the top of the central channel of the slit heat exchanger, with the flow guide located at the top of the impurity adsorber.

[0013] Preferably, both the slit heat exchanger and the sealing shell are made of oxygen-free copper.

[0014] Preferably, the inflation tube is a copper tube and is welded and fixed to the sealing shell.

[0015] Preferably, the air inlet connector, the air outlet connector, and the connecting flange are all made of stainless steel.

[0016] The present invention achieves the following technical effects compared to the prior art:

[0017] The low-temperature heat exchanger of this invention features a sealed outer shell outside the slit heat exchanger wall, with a heat transfer medium at a suitable pressure filling the resulting cavity. When the cold end temperature drops below the critical temperature of the heat transfer medium, the medium liquefies and flows downwards under gravity. The liquefied medium vaporizes under the heating of the lower wall and flows upwards, thus forming a two-phase heat exchange cycle. This significantly reduces the wall temperature difference of the slit heat exchanger, thereby improving heat exchange efficiency. The two-phase heat exchange cycle, similar to a gravity heat pipe, used in this invention improves heat exchange efficiency and reduces the volume and weight of the heat exchanger compared to simple heat conduction, and can better reduce the wall temperature.

[0018] Furthermore, by arranging a flow guide after the air inlet, turbulence caused by significant changes in the flow channel diameter can be effectively reduced, and flow resistance losses during the flow process can be decreased. Simultaneously, the flow guide also acts as a retainer for the porous material in the impurity adsorber, preventing the porous particulate material from leaking out of the air inlet. The porous media surface within the arranged impurity adsorber can adsorb impurity gases at low temperatures. Finally, the slit heat exchanger pre-cools the gaseous working fluid to a suitable temperature through convective heat exchange between the wall and the working fluid. The arrangement of this invention integrates the functions of flow stabilization, impurity removal, and pre-cooling heat exchange, resulting in a compact structure. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a three-dimensional structural diagram of the low-temperature heat exchanger in this invention;

[0021] Figure 2 This is a cross-sectional view of the low-temperature heat exchanger in this invention;

[0022] Figure 3 This is a three-dimensional structural diagram of the slit heat exchanger in this invention;

[0023] In the diagram: 1. Inlet connector; 2. Connecting flange; 3. Flow guide; 4. Impurity adsorber; 5. Slit heat exchanger; 6. Sealing shell; 7. Heat transfer medium; 8. Inlet pipe; 9. Outlet connector. Detailed Implementation

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0025] The purpose of this invention is to provide a low-temperature heat exchanger to solve the problems existing in the prior art. A sealed outer shell is installed outside the wall of the slot heat exchanger, and a heat transfer medium at a suitable pressure is filled in the formed cavity. When the cold end temperature is lower than the critical temperature of the heat transfer medium, the heat transfer medium liquefies and flows downward under the action of gravity. The liquefied heat transfer medium vaporizes under the heating of the lower wall and flows upward, thereby forming a two-phase heat exchange cycle. This significantly reduces the wall temperature difference of the slot heat exchanger, achieving the goal of improving heat exchange efficiency.

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The low-temperature heat exchanger in this embodiment, such as Figures 1-3 As shown, it includes a slit heat exchanger 5, an inlet connector 1, an outlet connector 9, and a sealing shell 6. The top and bottom ends of the slit heat exchanger 5 are connected to the inlet connector 1 and the outlet connector 9, respectively. The sealing shell 6 is provided on the outside of the slit heat exchanger 5. A sealed cavity capable of accommodating the heat transfer medium 7 is formed between the sealing shell 6 and the slit heat exchanger 5. An air filling pipe 8 for filling the heat transfer medium 7 into the sealed cavity is provided on the sealing shell 6.

[0028] In this specific embodiment, the top and bottom ends of the slit heat exchanger 5 are integrally provided with a top connecting plate and a bottom connecting plate, respectively. The two ends of the sealing shell 6 are welded to the top connecting plate and the bottom connecting plate to achieve sealing. The slit heat exchanger 5 contacts the low-temperature cold source through the upper end surface of the top connecting plate.

[0029] 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 into 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.

[0030] In this specific embodiment, the air intake connector 1 is connected to the connecting flange 2 by screws. The connecting flange 2 is welded to the top connecting plate. The connecting flange 2 has a groove for installing a metal gasket as a sealing material to achieve a sealed connection with the air intake connector 1.

[0031] 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.

[0032] 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. The flow guide 3 is located on top of the impurity adsorber 4. The flow guide 3 is composed of stainless steel wire mesh or made of porous stainless steel plate. The impurity adsorber 4 is usually porous activated carbon.

[0033] In this specific embodiment, both the slit heat exchanger 5 and the sealing shell 6 are made of oxygen-free copper, and the slit heat exchanger 5 has multiple slits cut inside.

[0034] In this specific embodiment, the inflation pipe 8 is a copper pipe and is welded and fixed to the sealing shell 6. The heat transfer medium 7 is filled into the sealing cavity composed of the slit heat exchanger body and the sealing shell 6 through the inflation pipe 8. When the appropriate pressure is reached, the inflation pipe 8 is clamped to achieve sealing.

[0035] During operation, the upper end of the slot heat exchanger 5 is connected to a cold source. The working gas requiring cooling to a low temperature enters vertically into the guide vane 3 from the inlet connector 1. The guide vane 3 is used to stabilize the flow and reduce turbulence during pipe diameter changes. After passing through the guide vane 3, the working gas enters the impurity adsorber 4. The porous material inside the impurity adsorber 4 can adsorb gaseous impurities other than the working gas at low temperatures. After passing through the impurity adsorber 4, the working gas enters the slot heat exchanger 5, where it achieves pre-cooling heat exchange by fully contacting the low-temperature wall surface through multiple slots. After gradually pre-cooling to a suitable low temperature, it flows out through the outlet connector 9. The heat transfer medium 7 between the slot heat exchanger 5 and the sealed outer shell 6 liquefies and condenses near the low-temperature cold source end, flowing downwards under gravity. At the lower end, it absorbs heat near the wall of the slot heat exchanger 5 and vaporizes upwards, thus achieving a two-way relative flow heat exchange cycle, reducing the axial (vertical) wall temperature difference of the slot heat exchanger 5, and improving heat exchange efficiency.

[0036] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A low-temperature heat exchanger, characterized in that: The device includes a slit heat exchanger, an inlet connector, an outlet connector, and a sealed outer shell. The top and bottom ends of the slit heat exchanger are connected to the inlet connector and the outlet connector, respectively. The sealed outer shell is disposed outside the slit heat exchanger, forming a sealed cavity between the sealed outer shell and the slit heat exchanger capable of containing the heat transfer medium. The sealed outer shell is provided with an air filling pipe for filling the sealed cavity with the heat transfer medium. The top and bottom ends of the slit heat exchanger are integrally provided with a top connecting plate and a bottom connecting plate, respectively. The two ends of the sealed outer shell are connected to the top connecting plate and the bottom connecting plate, respectively. The slit heat exchanger contacts a low-temperature cold source through the upper end surface of the top connecting plate. The slit heat exchanger utilizes a two-phase heat exchange cycle similar to a gravity heat pipe.

2. The low-temperature heat exchanger according to claim 1, characterized in that: The air inlet connector is fixed to the top connecting plate via a connecting flange, and the air outlet connector is welded to the center hole of the bottom connecting plate.

3. The low-temperature heat exchanger according to claim 2, characterized in that: The air intake connector is connected to the connecting flange by screws, and the connecting flange is welded to the top connecting plate.

4. The low-temperature heat exchanger according to claim 1, characterized in that: The air inlet channel of the air inlet connector, the central channel of the slit heat exchanger, and the air outlet channel of the air outlet connector are concentric channels.

5. The low-temperature heat exchanger according to claim 1, characterized in that: A flow guide and an impurity adsorber are provided at the medium inlet at the top of the central channel of the slit heat exchanger, with the flow guide located at the top of the impurity adsorber.

6. The low-temperature heat exchanger according to claim 1, characterized in that: Both the slit heat exchanger and the sealed outer shell are made of oxygen-free copper.

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

8. The low-temperature heat exchanger according to claim 2, characterized in that: The air inlet connector, the air outlet connector, and the connecting flange are all made of stainless steel.

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