High aspect ratio metal foam microchannel phase change cooling device composited with aluminum substrate

Abstract

The present invention discloses a high aspect ratio foam metal microchannel phase change cooling device composited with an aluminum substrate, comprising a heat sink chamber, a condenser, a liquid storage tank and a micro pump, wherein the heat sink chamber, the condenser, the liquid storage tank and the micro pump are sequentially connected through pipelines to form a closed loop, wherein the heat sink chamber comprises a foam metal microchannel, wherein the foam metal microchannel adopts a plurality of parallel arranged grooves, wherein one side of the groove is provided with an inlet chamber, and the other side is provided with an outlet chamber, wherein the bottom of the foam metal microchannel is fixed with an aluminum substrate, wherein the liquid working medium in the liquid storage tank enters the heat sink chamber under the action of the micro pump, and after being vaporized in the heat sink chamber, flows back to the liquid storage tank through the condenser. The present invention combines a high aspect ratio microchannel with a foam metal and composites it with an aluminum substrate, wherein the foam metal can greatly increase the heat exchange area, increase the vaporization core density, and can effectively supply liquid through its capillary force during boiling heat exchange without drying up, and the high aspect ratio microchannel can make bubbles flow upward.

Description

Technical Field

[0001] The invention relates to a heat dissipation device, in particular to a high aspect ratio foam metal microchannel phase change cooling device composited with an aluminum substrate. Background Art

[0002] In recent years, the requirements for heat dissipation and heat exchange of electronic equipment have become increasingly higher. From the current research, the heat dissipation of electronic chips is currently mainly achieved by air cooling, liquid cooling, heat pipes and microchannels. Air cooling is difficult to cope with the challenges of high heat flux density devices; heat pipe cooling modules are limited by phenomena such as carrying limit and drying limit; liquid cooling, its heat exchange performance is difficult to meet the requirements of future high-power electronic devices, and phase change heat transfer, because it can achieve extremely high heat transfer coefficients, has attracted much attention in applications. A large number of studies have found that: on the one hand, the heat transfer coefficient of microchannels with high aspect ratios is much higher than that of conventional channels; on the other hand, the enhancement of boiling heat transfer by foam metals has also been confirmed. Due to the presence of a large number of tiny pores, the vaporization core density can be greatly increased, the wall superheat can be reduced, and the capillary force provided by the tiny pores can also greatly enhance the liquid supply to the heated surface, thereby avoiding the occurrence of drying. This provides a new way to dissipate heat for future ultra-high heat flux density electronic devices.

[0003] Chinese patent CN201210100441.X, a chip cooling system based on foam metal enhanced boiling heat transfer, actually provides a gravity heat pipe working mode, using serrated foam metal in a closed cavity to enhance the boiling heat transfer of the working fluid, which can reduce the surface temperature of the bottom heating surface to a certain extent. However, the system will be subject to restrictions such as the carrying limit of the gravity heat pipe when working, and this patent discusses pool boiling, and the heat transfer performance is limited. The external fan driven by the internal cavity airflow considered in the system is difficult to solve the vacuum sealing problem, so its feasibility is questionable.

[0004] Chinese patent CN201010019414.0 proposes a heat exchange plate based on staggered interconnected network structure microchannels. The microchannels in this patent are composed of two layers of microchannels, upper and lower. Through a special mechanical processing method, the upper channel and the lower channel are perpendicular to each other, and finally an interconnected microchannel is formed. The grooves of the lower microchannel are conducive to nucleation and bubble overflow, and have excellent boiling enhancement performance. However, this double-layer microchannel still cannot effectively eliminate bubbles, which is a difficult problem in microchannel boiling heat exchange, and it is difficult to exceed 100W / cm in terms of CHF improvement. 2 above. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to address the deficiencies of existing phase change cooling systems and to provide a high aspect ratio foam metal microchannel phase change cooling device composited with an aluminum substrate.

[0006] Technical solution: The present invention includes a heat sink chamber, a condenser, a liquid storage tank and a micro pump. The heat sink chamber, condenser, liquid storage tank and micro pump are connected in sequence through pipelines to form a closed loop. The heat sink chamber includes a foam metal microchannel. The foam metal microchannel adopts a plurality of high aspect ratio grooves arranged in parallel. An inlet chamber is provided on one side of the groove, and an outlet chamber is provided on the other side. An aluminum substrate is fixed to the bottom of the foam metal microchannel. The liquid working medium in the liquid storage tank enters the heat sink chamber under the action of the micro pump, and after being vaporized in the heat sink chamber, it flows back to the liquid storage tank through the condenser.

[0007] The foam metal microchannel adopts a rectangular channel with a high aspect ratio, and the aspect ratio is 5-10.

[0008] The foam metal microchannel is made of foam aluminum or foam copper, with a porosity of 0.7-0.9 and a pore density of 60-100 PPI. The number of microchannels is determined according to the area to be cooled.

[0009] The heat sink chamber shell is made of aluminum alloy profile, the inlet chamber is connected to the precooler, and the outlet chamber is connected to the condenser.

[0010] The aluminum substrate comprises an aluminum alloy bottom plate, an electrical insulation layer and a heat source in order from top to bottom, and the aluminum alloy bottom plate is fixed to the foam metal microchannel by welding.

[0011] The outlet of the liquid storage tank is provided with a regulating valve, and the liquid storage tank is connected with a micro pump through a filter.

[0012] The liquid working medium in the liquid storage tank is an insulating dielectric liquid.

[0013] The micro pump is a micro gear pump or a peristaltic pump.

[0014] A precooler is provided between the micro pump and the heat sink chamber.

[0015] The pipeline is made of copper pipe or stainless steel pipe.

[0016] Working principle: The liquid working medium in the liquid storage tank enters the heat sink chamber under the action of the micro pump, and is heated and boiled in the foam metal microchannel to be transformed into a vapor working medium. The heat of the high heat flux density heat source at the bottom of the aluminum substrate is taken away by the vapor-liquid two-phase flow, and is dissipated to the external environment by air cooling in the condenser. At the same time, the vapor working medium is converted back into a liquid working medium and flows back to the liquid storage tank for reciprocating circulation.

[0017] Beneficial effects: The present invention combines a high aspect ratio microchannel with foamed metal and compounds it with an aluminum alloy substrate. The foamed metal can greatly increase the heat exchange area, greatly increase the vaporization core density, and can effectively supply liquid through its capillary force during boiling heat exchange without drying up. The high aspect ratio microchannel can make the bubbles drain upward, so that when the device is working, the lower layer of the microchannel can be regarded as a liquid working fluid channel, and the upper layer can be regarded as a vapor working fluid channel, thereby realizing gas-liquid separation, and the phenomenon that large bubbles aggregated in conventional microchannels expand upstream due to channel restrictions will not occur, thereby greatly improving the critical heat flux density CHF limit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0019] Figure 2 A schematic diagram of a foam metal microchannel of the present invention;

[0020] Figure 3 It is the layout diagram of the heat sink chamber of the present invention;

[0021] Figure 4 It is a schematic diagram of an aluminum substrate of the present invention;

[0022] Figure 5 It is a schematic diagram of a liquid storage tank of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings.

[0024] like Figures 1 to 5 As shown, the present invention includes a heat sink chamber 1, a condenser 6, a liquid storage tank 4, a filter 5, a micro pump 3 and a precooler 11. The heat sink chamber 1, the condenser 6, the liquid storage tank 4, the filter 5, the micro pump 3 and the precooler 11 are sequentially welded and connected through a pipeline 12 to form a closed loop. The pipeline 12 is made of a copper tube or a stainless steel tube. Figure 3 As shown, the heat sink chamber 1 adopts a rectangular cavity structure, with a foam metal microchannel 2 in the center, an outlet chamber 14 on one side of the foam metal microchannel 2, and an inlet chamber 13 on the other side. The liquid working medium 7 in the liquid storage tank 4 enters the heat sink chamber 1 under the action of the micro pump 3, and is heated and boiled in the foam metal microchannel 2 to be transformed into a vapor working medium, and the heat of the high heat flux density heat source on the upper end of the aluminum substrate 8 is taken away by the vapor-liquid two-phase flow, and is dissipated to the external environment in the condenser 6 by air cooling.

[0025] The structure of the foam metal microchannel 2 is as follows Figure 2As shown, a rectangular channel with a high aspect ratio is used. The microchannel with a high aspect ratio is made by a mechanical processing method. After processing, the foam metal microchannel 2 needs to be cleaned to remove the oxide layer. The rectangular channels are evenly arranged in parallel along the width direction of the heat sink chamber 1. One side of the rectangular channel is connected to the inlet chamber 13, and the other side is connected to the outlet chamber 14. The aspect ratio of the microchannel is 5 to 10, the microchannel width is 0.2 to 0.4 mm, the microchannel height is 1 to 4 mm, the rib column width between adjacent microchannels is 0.2 to 0.4 mm, and the number of microchannels depends on the area to be cooled. The foam metal in the foam metal microchannel 2 is foam aluminum or foam copper, etc., with a porosity of 0.7 to 0.9 and a pore density of 60 to 100 PPI. An aluminum substrate 8 is fixed to the bottom of the foam metal microchannel 2, and the aluminum substrate 8 and the foam metal microchannel 2 are connected by vacuum brazing, and the welding temperature is 640°C. The length of the aluminum substrate 8 is equal to that of the heat sink chamber 1. The cavity shell of the heat sink chamber 1 is made of aluminum alloy profiles. The design of the heat sink chamber 1 needs to ensure the uniformity of the parallel microchannel liquid separation. A cover plate 15 is provided on the top of the heat sink chamber. The size of the cover plate 15 is the same as the outer size of the heat sink chamber 1. The aluminum substrate 8 and the heat sink chamber 1 are welded and packaged. Through welding, they are composited with the aluminum alloy bottom plate of the aluminum substrate 8 to reduce the interface thermal resistance and obtain a very high CHF critical heat flux density.

[0026] like Figure 4 As shown, the aluminum substrate 8 includes an aluminum alloy bottom plate, an electrical insulation layer and a heat source 10 from top to bottom. The aluminum alloy bottom plate and the electrical insulation layer are bonded together by epoxy resin glue, and the aluminum alloy bottom plate is welded to the bottom of the heat sink chamber 1. A plurality of heat sources 10 are arranged at the bottom of the electrical insulation layer. The inlet chamber 13 of the heat sink chamber 1 is connected to the precooler 11, which is a plate heat exchanger. The temperature of the liquid working medium 7 at the inlet of the heat sink chamber 1 is ensured by cooling water; the outlet chamber 14 of the heat sink chamber 1 is connected to the condenser 6. The condenser 6 adopts a self-cooling convection air-cooled heat exchanger. The air-cooled condenser should ensure sufficient compactness and efficient heat dissipation to save corresponding space. The outlet of the condenser 6 is connected to the liquid storage tank 4, as shown in FIG. Figure 5 As shown, the liquid storage tank 4 is a tank-shaped container for storing liquid working medium 7, which is welded and processed by stainless steel. The side and bottom are provided with inlet and outlet pipe joints, and a liquid level gauge is attached. It is connected to the circulation pipeline in parallel. The liquid working medium 7 inside is Freon or insulating dielectric fluid. The outlet of the liquid storage tank 4 is connected to the filter 5 through the regulating valve 9, and the mesh number of the drying filter is 200-300 meshes. The outlet of the filter 5 is connected to the micro pump 3, which is a micro gear pump or a peristaltic pump, and its outlet is connected to the precooler 11. The system pipeline must be cleaned, leak-checked, pressure-maintained, and vacuumed before the working medium is injected.

[0027] The liquid working medium 7 in the liquid storage tank 4 of the present invention enters the heat sink chamber 1 under the action of the micro pump 3, is heated and boiled in the foam metal microchannel 2 and is converted into a vapor working medium, and the heat of the high heat flux density heat source 10 at the bottom of the aluminum substrate 8 is taken away by the vapor-liquid two-phase flow, and is dissipated to the external environment by air cooling in the condenser 6, and the vapor working medium is converted back into a liquid working medium 7 and enters the liquid storage tank 4, and the cycle is repeated.

Claims

1. A high aspect ratio foam metal microchannel phase change cooling device composited with an aluminum substrate, characterized in that: The heat sink chamber comprises a heat sink chamber, a condenser, a liquid storage tank and a micro pump, wherein the heat sink chamber, the condenser, the liquid storage tank and the micro pump are sequentially connected through pipelines to form a closed loop, wherein the heat sink chamber comprises a foam metal microchannel, wherein the foam metal microchannel adopts a plurality of parallel arranged high aspect ratio grooves, wherein an inlet chamber is arranged on one side of the groove, and an outlet chamber is arranged on the other side, and an aluminum substrate is fixed to the bottom of the foam metal microchannel, and the liquid working medium in the liquid storage tank enters the heat sink chamber under the action of the micro pump, and after being vaporized in the heat sink chamber, flows back to the liquid storage tank through the condenser; The high aspect ratio microchannel can make the bubbles go up, so when the device is working, the lower layer of the microchannel can be regarded as a liquid working medium channel, and the upper layer can be regarded as a vapor working medium channel, thereby realizing gas-liquid separation. The foam metal microchannel adopts a groove with a high aspect ratio, and its high aspect ratio is 5~10. The foam metal microchannel adopts foam aluminum or foam copper, whose porosity is 0.7~0.9 and pore density is 60~100PPI. The shell of the heat sink chamber is made of aluminum alloy profile, and its inlet chamber is connected to the precooler, and the outlet chamber is connected to the condenser.

2. The high aspect ratio foam metal microchannel phase change cooling device composited with an aluminum substrate according to claim 1, characterized in that: The foam metal microchannel adopts a rectangular groove.

3. The high aspect ratio foam metal microchannel phase change cooling device composited with an aluminum substrate according to claim 1, characterized in that: The aluminum substrate comprises an aluminum alloy bottom plate, an electrical insulation layer and a heat source in order from top to bottom, and the aluminum alloy bottom plate is fixed to the foam metal microchannel by welding.

4. The high aspect ratio foam metal microchannel phase change cooling device composited with an aluminum substrate according to claim 1, characterized in that: The outlet of the liquid storage tank is provided with a regulating valve, and the liquid storage tank is connected with a micro pump through a filter.

5. The high aspect ratio foam metal microchannel phase change cooling device composited with an aluminum substrate according to claim 1, characterized in that: The liquid working medium in the liquid storage tank is an insulating dielectric liquid.

6. The high aspect ratio foam metal microchannel phase change cooling device composited with an aluminum substrate according to claim 1, characterized in that: The micro pump is a micro gear pump or a peristaltic pump.

7. The high aspect ratio foam metal microchannel phase change cooling device composited with an aluminum substrate according to claim 1, characterized in that: A precooler is provided between the micro pump and the heat sink chamber.

8. The high aspect ratio foam metal microchannel phase change cooling device composited with an aluminum substrate according to claim 1, characterized in that: The pipeline is made of copper pipe or stainless steel pipe.

Images