Experimental Study On The Effect Of Additives On Spray Cooling

The miniaturization and integration technology of electronic devices have developed rapidly,and the power density has become higher and higher.The problem of heat dissipation has become a major technical bottleneck restricting the development of high-power electronic devices.Spray cooling has the advantages of strong heat dissipation capacity,small demand for cooling medium and effective temperature control,etc.,and has broad application prospects in solving the problem of heat dissipation of electronic devices.This article proposes a method of adding alcohol additives in deionized water to enhance the spray cooling heat transfer performance and conducts an experimental study.The main work of this article includes the following aspects:Firstly,designed and built spray cooling bench.The entire spray cooling system consists of three sub-systems,the liquid supply and spray system,the heating system,and the data and image acquisition system.First,the components and the key equipment used in each subsystem are described.Then the principle and method of measuring the surface tension and contact angle of alcohol water mixed solution are described.The definition and error analysis method of the parameters in the experiment are described later.Secondly,the surface tension and contact angle of the alcohol-water mixed solution were measured.The results showed that the alcohol additive has a significant effect on the surface tension and contact angle of the deionized water-based liquid,and the surface tension and contact angle of the binary mixture of alcohols and waters decrease with increasing concentration of alcohol additives.Using a high-speed camera to observe the characteristics of the spray wall,the alcohol-water mixed solution is sprayed onto the cooled surface to form a liquid film through the nozzle atomization,and a large number of bubbles are generated in the liquid film.Finally,the spray-cooling experiments were carried out with binary mixtures of ethanol-water,n-propanol-water,isopropanol-water,n-butanol-water,and n-pentanol-water as the circulating cooling media.The experimental results show that the alcohol additive has a significant strengthening effect on the spray cooling heat transfer performance,and there is an optimal concentration of addition.In this experiment,the optimal concentration of ethanol is 4%.When the wall temperature is 98°C,the heat transfer increases 50%;the optimal concentration of n-propanol is 4%.When the wall temperature is 102°C,the heat transfer increases by 35.1%;the optimal concentration of isopropyl alcohol is 2%,when the wall temperature is 100°C The heat transfer increased by 44.5%;the optimum concentration of n-butanol was 0.5%.At a wall temperature of 103°C,the heat transfer increased by 31.1%;the optimum concentration of n-pentanol was 0.1% at a wall temperature.At 101°C,the heat transfer increased by 9.9%.The experiment also found that: the surface temperature non-uniformity increases with the increase of heat flux,the highest surface temperature point is located at the center of the heating surface,with the increase of radius,the surface temperature drops,and then rises after decreasing to the minimum value;Compared to deionized water,the alcohol-water mixed solution has no significant effect on surface temperature non-uniformity.