A manifold microchannel evaporator and a gravity-type separate heat pipe system thereof

Abstract

The application provides a manifold micro-channel evaporator and a gravity type separate heat pipe system thereof, which comprises a manifold micro-channel evaporator as an evaporation end, a flow guide fin type radiator as a condensation end, a steam riser and a condensate return pipe connecting the evaporation end and the condensation end, and a working medium filled in the gravity type separate heat pipe system. The manifold micro-channel evaporator comprises a third layer, a second layer, a first layer and a fourth layer, the second layer comprises a plurality of inlet through holes and outlet through holes penetrating the second layer, and the inlet through holes and the outlet through holes are communicated with an inlet manifold and an outlet manifold respectively; the third layer is provided with micro-channels in the upper part; the flow guide fin is provided with an outer shell in the upper part, and a refrigerant outlet hole is arranged on the outer shell. The design of the manifold micro-channel shortens the flow path of the fluid in the micro-channel, reduces the overall pressure drop of the system, and also has the advantage of impinging jet, and further strengthens heat exchange by intensifying the disturbance of the fluid.

Description

Technical Field

[0001] This invention relates to the field of heat exchange, and in particular to a gravity-type split heat pipe system using a manifold microchannel evaporator. Background Technology

[0002] A heat exchanger is a device that exchanges heat between hot and cold fluids. Heat exchangers are widely used in many fields. In industries such as electronics, petrochemicals, communications, and aerospace, the unique operating environments impose special requirements on the size and weight of heat exchangers, demanding higher heat exchange capacity. In 1981, scholars proposed using microchannels for heat dissipation, which could reduce the size of the heat exchanger and significantly improve its heat exchange capacity by utilizing the high specific surface area of ​​the microchannels. However, although it has a strong heat exchange capacity, the overall pressure loss is also relatively high due to the small hydraulic diameter of the microchannels.

[0003] Heat pipe technology utilizes heat transfer theory and the rapid heat transfer properties of phase change media to quickly transfer heat from a heat source to the outside, with a thermal conductivity exceeding that of any known metal. Therefore, since its inception, heat pipe technology has become a hot research topic for numerous scholars both domestically and internationally in recent decades.

[0004] Split-type heat pipes are an innovative form of heat pipe technology, representing a highly efficient heat transfer system. By establishing independent evaporation and condensation sections between the heat source and heat dissipation source, split-type heat pipes utilize the phase change process of the internal working fluid to achieve heat transfer without any external power assistance. Their structural features include phase separation of the evaporation and condensation sections, internal vacuum insulation technology, and advantages such as high transfer efficiency, fast thermal response, flexible structure, and ease of expansion and maintenance. They are widely used in data centers, solar thermal collectors, and industrial waste heat recovery.

[0005] A split heat pipe mainly consists of an evaporator section, a condenser section, connecting pipes, a working fluid, and a vacuum insulation layer. Its working principle is as follows: a heat source transfers heat to the evaporator section, causing the working fluid to absorb heat and evaporate. The vapor flows through the connecting pipes to the condenser section, where it releases heat and condenses into a liquid. Using gravity or a micro-pump, the condensate returns to the evaporator section to absorb heat and evaporate again, forming a closed loop. During this process, the vacuum insulation layer ensures efficient heat insulation inside the heat pipe, reducing heat loss. The design of the evaporator and condenser sections is crucial to the performance of a split heat pipe, directly affecting its heat transfer efficiency and overall operational stability.

[0006] With the continuous development of technology, the required heat flux density of many machines and equipment is also increasing. Therefore, to maintain the normal operation of these machines, significant heat dissipation is necessary. However, traditional air-cooling technologies have limited cooling capacity and high energy consumption, making them unable to meet current cooling demands. Therefore, developing new, efficient, and low-energy-consumption cooling methods is imperative.

[0007] To address this issue, the primary method currently employed in heat dissipation equipment is liquid cooling technology. Liquid cooling can be categorized into indirect and direct cooling. Evaporator cooling is one of the main forms of indirect cooling, involving etching uniformly fine microchannels within the evaporator to allow the working fluid to flow directionally within these channels. The microchannel structure increases the convective heat transfer area and enhances the convective heat transfer intensity, thereby effectively strengthening heat transfer. Patent CN 111678364 A discloses a high-efficiency microchannel heat exchanger that effectively increases heat transfer efficiency by creating grooves on the sidewalls of the guide vanes, utilizing the heat transfer space formed by these grooves to create secondary heat transfer channels. However, in this patent, due to the presence of viscous forces, the working fluid within the microchannels experiences significant frictional losses along the flow direction, resulting in substantial flow losses.

[0008] Split-type heat pipe cooling is a form of indirect cooling. Its basic principle is to use a fan or similar means to transfer heat from the electronic device to the evaporation end of the split-type heat pipe. Heat transfer between the evaporation and condensation ends is achieved through the phase change heat transfer of the refrigerant within the split-type heat pipe, thus reducing the target temperature. Patent CN 113056167 A discloses a liquid-cooled server heat dissipation device based on a split-type heat pipe heat exchanger, which can significantly simplify the internal structure of the system, reduce energy consumption, and improve heat dissipation efficiency. While immersion cooling in this patent can significantly reduce the temperature of electronic devices, for electronic devices with very high local hot spots, the heat dissipation capacity of simple immersion cooling is limited, and overheating of heat-generating components can still occur. Furthermore, simple immersion cooling has a complex structure and a large footprint. Summary of the Invention

[0009] The purpose of this invention is to provide a manifold microchannel evaporator and a gravity-type split heat pipe system using the manifold microchannel evaporator. The manifold microchannel design shortens the flow path of the fluid within the microchannel, reduces the overall pressure drop of the system, and also possesses the advantages of impingement jets, further enhancing heat transfer by intensifying fluid turbulence. The evaporator can also improve upon the problems of immersion cooling failing to address localized hot spots and easily leading to overheating of heating components, while also solving the problems of complex structure and large footprint.

[0010] To achieve the above objectives, the technical solution of the present invention is as follows: A manifold microchannel evaporator includes a fourth layer, a first layer, a second layer, and a third layer stacked sequentially from top to bottom. The fourth layer includes a refrigerant inlet manifold, a refrigerant inlet manifold, a refrigerant outlet manifold, a refrigerant outlet manifold, and a guide vane. The refrigerant inlet manifold and refrigerant outlet manifold extend vertically through the fourth layer. The guide vane is located at the outlet of the refrigerant outlet manifold in the upper part of the fourth layer. The refrigerant inlet manifold is located in the lower part of the fourth layer and communicates with the inlet manifold. The refrigerant outlet manifold is located in the lower part of the fourth layer and communicates with the outlet manifold. The second layer includes multiple inlet and outlet through holes extending vertically through the second layer, which communicate with the inlet and outlet manifolds, respectively. A microchannel is provided in the upper part of the third layer. The inlet manifold, outlet manifold, inlet through holes, and outlet through holes are all strip-shaped structures. The guide vane is arranged perpendicular to or inclined to the strip-shaped structure of the refrigerant outlet manifold. A shell is provided on the upper part of the guide vane, and a refrigerant outlet hole is provided on the shell.

[0011] As an improvement, the refrigerant outlet manifolds are multiple in parallel, each with its own guide vanes and housing. Each housing has a refrigerant outlet hole, and each refrigerant outlet hole connects to an outlet pipe. The multiple outlet pipes are connected to the main pipe.

[0012] As an improvement, the angle of inclination of the guide vane relative to the upper surface of the first layer is preferably 50-70°.

[0013] As an improvement, the guide vanes of the refrigerant outlet manifold are set with different tilt directions, wherein the guide vanes on both sides of the refrigerant outlet hole are tilted in opposite directions and are both tilted toward the refrigerant outlet hole.

[0014] As an improvement, the tilt angle of the guide vanes gradually decreases from the location of the refrigerant outlet hole towards both ends of the refrigerant outlet manifold.

[0015] As an improvement, the refrigerant outlet hole is located in the middle of the refrigerant outlet manifold, that is, the outer casing is located in the middle of the refrigerant outlet manifold direction.

[0016] The working method of the manifold microchannel evaporator is as follows: the refrigerant enters the evaporator from the refrigerant inlet manifold, and then enters the refrigerant inlet manifold. After being divided into multiple fluids at the manifold, the refrigerant impacts the third layer downwards and flows to both sides along the microchannel direction. The refrigerant then leaves the third layer from the refrigerant outlet manifold. After leaving the third layer, the refrigerant will also pass through the refrigerant outlet guide vane. Here, the refrigerant is fully dispersed and guided to the refrigerant outlet manifold, optimizing the fluid flow in the fourth layer.

[0017] A gravity-type split heat pipe system includes a finned radiator, a manifold microchannel evaporator, a vapor riser, and a condensate downcomer. The system is filled with a certain volume of refrigerant. The finned radiator cools the gaseous refrigerant entering it, while the manifold microchannel evaporator absorbs the heat generated by the cooling target using the liquid refrigerant. The vapor riser and condensate downcomer connect the finned radiator and the manifold microchannel evaporator to form a circulation loop. The lower part of the third layer is thermally connected to the main heat-generating component, and the finned radiator is connected to a fan. Compared with the prior art, this invention has the following advantages: 1. The purpose of this invention is to provide a manifold microchannel evaporator and a gravity-type split heat pipe system using the manifold microchannel evaporator. The manifold microchannel design shortens the flow path of the fluid within the microchannel, reduces the overall pressure drop of the system, and also possesses the advantages of impingement jets, further enhancing heat transfer by intensifying fluid turbulence. Combining the evaporator with immersion cooling can also improve the problem that immersion cooling cannot solve local hot spots and easily leads to overheating of heat-generating components.

[0018] 2. This invention also fully considers the characteristics of high refrigerant velocity and high temperature at the refrigerant outlet manifold, which may cause a strong impact on the fourth layer. Low-density guide vanes are arranged at the refrigerant outlet. These vanes can effectively disperse the fluid, reduce the strong impact of the refrigerant on the fourth layer, reduce the impact of the fluid on the shell, and further reduce noise. They also guide the refrigerant to the outlet and increase the heat exchange area, further enhancing the heat exchange effect.

[0019] 3. This invention allows the outlet fluid to flow at an angle towards the refrigerant outlet hole, further ensuring that the fluid flows out in the middle, reducing flow resistance. Simultaneously, the two opposing fluid streams can cancel each other out, thus reducing fluid flow velocity while ensuring enhanced heat transfer and minimizing potential strong impact on the fourth layer. This further reduces the impact of the fluid on the casing and further reduces noise.

[0020] 4. This invention employs a discrete heat pipe design to construct a heat dissipation system that directly contacts the server chip. It achieves indirect liquid cooling with phase change heat dissipation for the chip, which has the highest power consumption and is most critical to performance, effectively controlling the chip temperature. It also features the flexibility and simplicity of discrete heat pipes, allowing for long-distance arrangement. Modification is simple, the structure is compact, and it can be adapted to specific server requirements using either hard or soft connections, making it highly adaptable. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the layered structure of the manifold microchannel evaporator of the present invention.

[0022] Figure 2 This is a schematic diagram of the first layer structure of the present invention.

[0023] Figure 3 This is a schematic diagram of the refrigerant flow in this invention.

[0024] Figure 4 This is a schematic diagram of the outer casing and the inclined guide vane at the outlet of the present invention. Figure 5 This is a schematic diagram of the outlet guide vane of the present invention tilting towards the center. Figure 6 This is a schematic diagram of the overall structure of the split heat pipe system of the present invention. Detailed Implementation

[0025] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0026] Unless otherwise specified, in this article, " / " represents division, and "×" and "*" represent multiplication.

[0027] Figure 1-3 The manifold microchannel evaporator of the present invention is shown. For example... Figure 1 As shown, the manifold microchannel evaporator includes a fourth layer 4 (outlet layer), a first layer 1 (inlet layer), a second layer 2 (manifold layer), and a third layer 3 (microchannel layer) stacked sequentially from top to bottom. The first layer 1 includes a refrigerant inlet manifold 11, a refrigerant inlet manifold 12, a refrigerant outlet manifold 13, and a guide vane 14. The refrigerant inlet manifold 11 and the refrigerant outlet manifold 13 extend vertically through the first layer 1. The guide vane 14 is located at the outlet of the refrigerant outlet manifold at the upper part of the first layer. The refrigerant inlet manifold 12... 2 is located at the lower part of the first layer 1 and is connected to the inlet manifold 11. The refrigerant outlet manifold 13 runs vertically through the first layer 1. The second layer 2 includes multiple inlet and outlet through holes that run vertically through the second layer 2. The inlet and outlet through holes are connected to the inlet manifold 12 and the outlet manifold 13, respectively. The upper part of the third layer 3 is provided with microchannels. The inlet manifold 12, the outlet manifold 13, the inlet through holes, and the outlet through holes are all strip-shaped structures. The guide vane 14 is arranged perpendicular to or inclined to the strip-shaped structure of the refrigerant outlet manifold. The upper part of the guide vane 14 is provided with a shell 5, and the shell is provided with a refrigerant outlet hole 51.

[0028] The purpose of this invention is to provide a manifold microchannel evaporator, wherein the design of the manifold microchannel shortens the flow path of the fluid in the microchannel, reduces the overall pressure drop of the system, and also has the advantages of impingement jet, further enhancing heat transfer by amplifying the turbulence of the fluid.

[0029] This invention also fully considers the characteristics of high refrigerant velocity and temperature at the refrigerant outlet manifold, which may cause strong impact and high flow resistance on the fourth layer. Low-density guide vanes are arranged at the refrigerant outlet. These vanes effectively disperse the fluid, reduce the strong impact of the refrigerant on the fourth layer, and guide it to flow towards the refrigerant outlet manifold. They also function similarly to fins, increasing the heat exchange area and further enhancing the heat exchange effect, while reducing the refrigerant pressure drop. Furthermore, the guide vanes effectively disperse the fluid, reduce the strong impact of the refrigerant on the fourth layer, and reduce the impact of the fluid on the shell, further reducing noise.

[0030] The evaporator of this invention, by setting guide vanes on the outer shell and the outlet, can also improve the problem that immersion cooling cannot solve the problem of local hot spots and easily leads to overheating of heating components, while also solving the problem of complex structure and large footprint.

[0031] As an improvement, the refrigerant outlet manifolds 13 are multiple in parallel, each individually equipped with a guide vane and a housing. Each housing has a refrigerant outlet hole, each outlet hole connects to an outlet pipe, and the multiple outlet pipes connect to the main pipe. Figure 6 As shown in the diagram. The above structure can further effectively disperse the fluid, reduce the strong impact of the refrigerant on the fourth layer, reduce the impact of the fluid on the casing, and further reduce noise.

[0032] Figure 3 The flow guide 14 is shown to be vertically positioned relative to the upper surface of the fourth layer 1. However, as an improvement, the flow guide can be an inclined structure. Figure 4 The diagram shows the flow guide 14 tilted at a certain angle relative to the upper surface of the fourth layer 1. This tilting design slows down fluid flow time, enhances heat transfer, and reduces fluid flow velocity, thus minimizing potential strong impacts on the fourth layer. This further reduces the impact of the fluid on the casing and further lowers noise levels.

[0033] The angle of inclination of the guide vane 14 relative to the upper surface of the first layer 1 is preferably 50-70°. This angle was obtained through extensive research. On the one hand, it can reduce the fluid flow velocity and reduce the strong impact that may be caused to the fourth layer; on the other hand, it can avoid excessive flow resistance. This further reduces the impact of the fluid on the shell and further reduces noise.

[0034] As an improvement, Figure 5The diagram illustrates the arrangement of guide vanes 14 with different inclination directions on the same refrigerant outlet manifold 13. The guide vanes 14 on both sides of the refrigerant outlet hole 51 are inclined in opposite directions, both towards the refrigerant outlet hole 51. This arrangement ensures that the outlet fluid flows at an angle towards the refrigerant outlet hole 51, further guaranteeing that the fluid flows out in the middle, reducing flow resistance. Simultaneously, the two opposing fluid flows can cancel each other out, thus enhancing heat transfer while reducing fluid flow velocity and minimizing potential strong impact on the fourth layer. This further reduces fluid impact on the casing and further lowers noise levels.

[0035] As an improvement, the tilt angle of the guide vanes gradually decreases from the refrigerant outlet hole 51 towards both ends of the refrigerant outlet manifold. This design prevents the fluid flowing along the tilted guide vanes from traveling further, causing it to essentially concentrate at the refrigerant outlet hole 51. This reduces the potential for strong impact on the fourth layer and decreases refrigerant flow resistance. It further reduces the impact of fluid on the casing and further lowers noise levels.

[0036] As an improvement, the angle of inclination of the guide vanes gradually decreases towards both ends of the refrigerant outlet manifold from the refrigerant outlet hole 51. This design further ensures that the fluid flowing along the inclined guide vanes cannot travel further, essentially concentrating at the refrigerant outlet hole 51. This reduces the potential for strong impact on the fourth layer and decreases refrigerant flow resistance. It also further reduces the impact of fluid on the casing, further lowering noise levels.

[0037] As an improvement, the refrigerant outlet hole 51 is located in the middle of the refrigerant outlet manifold 13, that is, the outer casing 5 is located in the middle of the refrigerant outlet manifold 13. This allows for uniform fluid distribution on both sides, achieving balanced heat exchange, and balanced fluid counterflow on both sides, further reducing noise.

[0038] As an improvement, the refrigerant inlet manifold 12 is designed with a tapered structure along the fluid flow direction. This tapered design effectively guides the refrigerant from the inlet header 11 to be evenly distributed into multiple inlet pipes. This not only reduces the velocity difference in fluid flow and lowers the pressure drop, but also ensures uniform distribution of the fluid before it enters the microchannels, avoiding localized hot spots.

[0039] As an improvement, multiple inlet manifolds 12 and outlet manifolds 13 are provided, arranged alternately. This alternating arrangement of the inlet manifolds 12 and outlet manifolds 13 ensures uniform fluid distribution and avoids localized hot spots.

[0040] As an improvement, multiple outlet manifolds 13 are provided, with the middle outlet manifold 13 being closer to the inlet than the two side outlet manifolds 13, and the width of the middle outlet manifold 13 being greater than that of the two side outlet manifolds 13. This can reduce the flow distance of the refrigerant in the microchannels, thereby reducing the temperature rise of the refrigerant and achieving more efficient cooling of the central area of ​​the heat dissipation component.

[0041] Figure 3 The operation of the manifold microchannel evaporator is demonstrated. Refrigerant enters the evaporator from the refrigerant inlet manifold 11, then flows into the refrigerant inlet manifold 12. At the manifold, it splits into multiple fluid streams. The refrigerant then impacts the third layer 3 downwards and flows to both sides along the microchannel direction. After being heated and vaporized, the refrigerant exits the third layer 3 from the refrigerant outlet manifold 13. After leaving the third layer, the refrigerant passes through the refrigerant outlet guide vane 14, where it is fully dispersed and guided to the refrigerant outlet manifold, optimizing the fluid flow in the fourth layer.

[0042] Figure 6 Demonstrates the use of Figure 1-3 The gravity-type split heat pipe system of the described manifold microchannel evaporator includes a manifold microchannel evaporator as the evaporation end, a finned radiator as the condensation end, a vapor riser pipe and a condensate return pipe connecting the evaporation and condensation ends, and a working fluid charged within the gravity-type split heat pipe system. Liquid refrigerant enters the manifold microchannel evaporator through the refrigerant inlet manifold, evaporates upon heating in the evaporator, and flows out through the refrigerant outlet manifold, carrying away the heat absorbed by the evaporator. Gaseous refrigerant enters the evaporation end, cools into a liquid state, and then flows back into the evaporator, completing the refrigerant cycle and heat transfer. The lower part of the third layer 3 is thermally connected to the main heating component to cool it down. The finned radiator is connected to heat dissipation components such as a fan to dissipate heat.

[0043] The purpose of this invention is to provide a manifold microchannel evaporator and a gravity-type split heat pipe system using the manifold microchannel evaporator. The manifold microchannel design shortens the flow path of the fluid within the microchannel, reduces the overall pressure drop of the system, and also possesses the advantages of impingement jets, further enhancing heat transfer by intensifying fluid turbulence. The evaporator can also improve upon the problem of immersion cooling failing to address localized hot spots and easily leading to overheating of heating components.

[0044] While the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A manifold microchannel evaporator, comprising a fourth layer, a first layer, a second layer, and a third layer stacked sequentially from top to bottom. The first layer includes a refrigerant inlet manifold, a refrigerant inlet manifold, a refrigerant outlet manifold, a refrigerant outlet manifold, and a guide vane. The refrigerant inlet manifold and refrigerant outlet manifold extend vertically through the first layer. The guide vane is disposed at the outlet of the refrigerant outlet manifold at the upper part of the first layer. The refrigerant inlet manifold is disposed at the lower part of the first layer and communicates with the inlet manifold. The refrigerant outlet manifold is disposed at the lower part of the first layer and communicates with the outlet manifold. The second layer includes a plurality of inlet through holes and outlet through holes extending vertically through the second layer. The inlet through holes and outlet through holes communicate with the inlet manifold and the outlet manifold, respectively. A microchannel is disposed at the upper part of the third layer. The inlet manifold, outlet manifold, inlet through holes, and outlet through holes are all strip-shaped structures. The guide vane is arranged perpendicular to or inclined to the strip-shaped structure of the refrigerant outlet manifold. The fourth layer consists of a shell disposed on the upper part of the guide vane, and a refrigerant outlet hole is disposed on the shell. The refrigerant outlet manifolds are multiple in parallel, each with its own guide vane and housing; each housing has a refrigerant outlet hole, each refrigerant outlet hole is connected to an outlet pipe, and the multiple outlet pipes are connected to the main pipe; The angle of inclination of the guide vane relative to the upper surface of the first layer; The guide vanes of the refrigerant outlet manifold are set with different tilt directions. The guide vanes on both sides of the refrigerant outlet hole are tilted in opposite directions and are both tilted towards the refrigerant outlet hole. The tilt angle of the guide vanes gradually decreases from the refrigerant outlet hole to both ends of the refrigerant outlet manifold.

2. The manifold microchannel evaporator as described in claim 1, characterized in that, The angle of inclination of the guide vane relative to the upper surface of the first layer is 50-70°.

3. The manifold microchannel evaporator according to claim 1, characterized in that, The refrigerant outlet hole is located in the middle of the refrigerant outlet manifold, that is, in the middle of the outer casing in the direction of the refrigerant outlet manifold.

4. The working method of the manifold microchannel evaporator as described in any one of claims 1-3, wherein the refrigerant enters the evaporator from the refrigerant inlet manifold, then enters the refrigerant inlet manifold, and after being divided into multiple fluid streams at the manifold, the refrigerant impacts the third layer downwards and flows to both sides along the microchannel direction. The refrigerant then leaves the third layer from the refrigerant outlet manifold. After leaving the third layer, the refrigerant will also pass through the refrigerant outlet guide vane. Here, the refrigerant is fully dispersed and guided to the refrigerant outlet manifold, optimizing the fluid flow in the fourth layer.

5. A gravity-type split heat pipe system, comprising a finned radiator, a manifold microchannel evaporator, a vapor riser, and a condensate downcomer, wherein a certain volume of refrigerant is charged in the system; the finned radiator is responsible for cooling the gaseous working fluid entering it, the manifold microchannel evaporator uses the liquid working fluid to absorb the heat generated by the cooling target, and the vapor riser and condensate return pipe connect the finned radiator and the manifold microchannel evaporator to form a circulation loop; the manifold microchannel evaporator is the evaporator as described in any one of claims 1-3; the lower part of the third layer is thermally connected to the main heating component, and the finned radiator is connected to a fan.

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