Heat Transfer Performance Analysis Of Aluminum Vapor Chamber Under Multiple Heating Sources

As the most effective passive heat transfer device,the vapor chamber radiator is widely used in LED,aerospace and other fields.Firstly,the paper conducted the research on the structure and manufacturing process of the aluminum vapor chamber.Then,the experimental research and numerical simulation research on heat transfer performance of vapor chamber with different liquid filling rates were carried out by changing external heat source environment.The research aims to analyze and summarize the systematic law of the environmental impact of heat sources,and to provide a reference for the application of the vapor chamber in engineering according to actual working conditions.Structure and technology research:the aluminum vapor chamber's size is 120×100×2 mm~3,which used the aluminum alloy material with high thermal conductivity and powder sintered wick and acetone as working fluid.Besides,the processing route of aluminum vapor chamber was established.Experimental research:the paper designed the air-cooled test device of vapor chamber and analyzed the start-up time with different filling rates and the thermal resistance at different heating powers by changing the heat source areas,numbers and locations.Finally,the start-up characteristics and heat transfer characteristics was obtained.The research analyzed the heat transfer performance and start-up performance parameters of the vapor chamber under the action of three or two heat source quantities respectively according to the area or the location of the heat source.As for the number of heat sources,the heat transfer performance and start-up performance parameters under two heat source areas were discussed.Studies has found that the increase of the heat source area and number will effectively improve the heat transfer performance by reducing the thermal resistance,but it will reduce the start-up performance as the start-up time increases.In addition,there are certain differences in the heat transfer performance of the vapor chamber under different heat source positions.When the area of heat source is small,changing the heat source position has the same effect on the performance as changing the heat source area and quantity.The start-up performance and heat transfer performance are less affected by the position of the heat source when the heat source area is large.Numerical simulation:the paper equated the heat transfer process of the vapor chamber to solid heat conduction process.Therefore,the research established six simplified models by applying isotropic or anisotropic equivalent thermal conductivity to different parts of the vapor chamber.Through the numerical simulation analysis of the selected working conditions,the result found that the simulation results of Model 4were in the highest agreement with the experimental values.Meanwhile,the vapor chamber with 40%liquid filling rate was numerically simulated under different heat source environments.The result found that the average surface temperature of the evaporation and the thermal resistance value will decrease with the increase of heat source area,which could improve the heat transfer performance.As the heating power increases,the slope of the average surface temperature curve at the evaporation gradually decreases,in addition,the average temperature gap narrows and gradually tends to the average surface temperature at the condensation.When the single heat source is on the left and the three heat sources are linearly distributed,the surface temperature of the evaporation is smaller and the thermal resistance is lower.The surface temperature rise of the evaporation is relatively gentle and the temperature uniformity is better with the increase of heating power.When the amount of heat increases,the temperature difference and the average surface temperature of the evaporation decreases,the temperature distribution becomes more uniform.When the heating power increases,the more heat source numbers,the lower average temperature of the evaporation surface achieved and better performance the vapor chamber obtained.