Experimental Investigation Of Pulsed Spray Cooling On A Hot Surface

With the rapid development of Integrated Microelectronics system, the traditional heat transfer ways have reached the limit of heat transfer capacity, which makes the electronics industry be in trouble. To solve this problem, the paper trys to find a new method to further enhance heat transfer capacity.Through the literature reviews, this paper sums up the factors, which affects boiling heat transfer and the heat transfer in spray cooling. After comparing the strength and weakness between boiling heat transfer and heat transfer in spray cooling, a new method pulsed spray cooling is provided in theory.First of all, nuclear boiling-related Bubble Dynamics is introduced, analyzing the impact of bubble dynamics. And then, four nuclear boiling heat transfer models are focused on. It provides the theoretical basis for analyzing pulsed spray cooling phenomenon and comparing heat transfer efficiency of traditional continuous spray cooling and pulsed spray cooling.In order to verify the feasibility of theoretical analysis, this paper carried out the experiment, further researching the theory of pulsed spray cooling, comparing heat transfer efficiency of traditional continuous spray cooling and pulsed spray cooling. Experimental results show that, when the half spray circle is 100ms or 150ms, the pulsed spray cooling has better surface convective heat transfer efficiency than continuous spray cooling. Especially, when the half spray circle is 100ms, the wall temperature reduces 12% compared to continuous spray cooling, while average surface convective heat transfer coefficient increases 18% compared to continuous spray cooling.Analyzing experimental results, it concludes that the pulsed spray cooling has three strengths: (1) The thickness of liquid film becomes thinner during the paused period, which reduces heat resistance. (2) The thickness of liquid film becomes thinner, which makes bubbles in liquid film vulnerable to droplets'influence, on the other hand, it reduces the bubbles'radius, increasing bubbles'escapes frequency. (3) Pulsed spray cooling reduces the interaction between steam and liquid droplet; the steam has enough time to spread around during the paused period.