Study On Heat Transfer Characteristics Of Spray Cooling On Radial Groove Surface

Spray cooling technology has many advantages,such as high heat transfer coefficient,excellent temperature uniformity,high utilization rate of cooling liquid and no hysteresis of boiling,which make it seen as feasible solution to cool electronic chips with high performance in the future.The experimental studies on the relationship between spray characteristic parameters and heat transfer performance has been fully developed.However,there are a lack of studies on the effects of groove structure characteristics on spray cooling,and the spray cooling calculation model due to incomplete research on heat transfer mechanism of it.In this paper,the way of mixing experimental and model study are used to investigate the heat transfer characteristics of spray cooling,especially on the radial groove surface.The main contents and conclusions are the following:1.The experimental system of spray cooling heat transfer performance was established,and is aimed to research the effects of spray flow on the heat transfer characteristics.The results indicate show that the increase of spray flow can increase the average heat flux and the liquid vaporization capacity,no matter it is the smooth surface or the radial groove surface.But it is hard to have a influence on the liquid outlet temperature and the vaporization ratio.2.The influence of surface structure on heat transfer characteristics was investigated.Compared with the smooth surface,the average heat flux on all the radial groove surface increases in different degrees.In the boiling region,the deeper groove,larger the wetting area,the more the number of core of vaporization,and the better the heat transfer process.But in the non-boiling region and transition region,the shallower groove makes it easier to discharge bubbles,so that the liquid film fluidity is better,the heat transfer is better3.The effects of closed groove on heat transfer performance was investigated.The average heat flux on closed groove surface is always less than that on open groove surface,which proves that the forced convection cannot be ignored in the process of spray cooling.It is also found in the study that the closed groove can reduce the drying area of the center of surface and make the surface temperature more uniform4.Based on experimental research and theoretical analysis,the heat transfer process of spray cooling in non-boiling region was simplified,and the model was established based on mass,momentum and energy conservation equation of liquid film.The order of magnitude analysis method is applied to simplify the equations,and numerical method is used to solve the equations.Experimental data are devoted to verify the model results,and they are highly consistent,which proves that the model is reliable5.Based on liquid flow and heat transfer model,the influence of spray parameter and surface structure on spray cooling heat transfer performance was studied.The results show that thinning film is the key to improving heat transfer in non-boiling region.It can reduce film thickness and enhance the heat transfer performance by increasing spray flux,increasing atomization angle and reducing spray height.The increase of groove number can make liquid flow from the top to the bottom,and reduce the liquid film thickness of the top of grooves,thus the performance of heat transfer is enhanced.Although the narrow groove can thicken the liquid film,the great increase of heat transfer area at the sides will enhance the heat transfer.