ANALYZING THE HEAT AND FLOW CHARACTERISTICS IN SPRAY COOLING BY USING AN OPTIMIZED RECTANGULAR FINNED HEAT SINK

Abstract

Rapid advancements in technology constantly keep the need for thermal systems, which have high performance, on the agenda and direct the attention of researcher-engineers to the studies on improving the heat transfer. Spray cooling process depends on many parameters including nozzle diameter, surface area, surface geometry, critical heat flux, mass flow, gravity, spraying angle, and surface slope. One would need results from many experiments to better analyze the spray structure. In the present study, by using the rectangular-finned heat sinks optimized for spray cooling and those called "general," the heat and flow characteristics in spray cooling were analyzed. Water was used as the cooling fluid and the cooling fluid was atomized by using an air-supported atomized. The experiments were conducted with six air-to-liquid ratio (ALR) values, three different jet heights, three different spraying times, three different fin heights, and three different fin widths. The results are presented in the Nusselt number-air-to-liquid ratio (Nu-ALR) and jet thickness-jet velocity (<i>t<sub>jet</sub> -U<sub>jet</sub></i>) diagrams. It was determined that the ALR value tended to decrease with increasing Nusselt numbers. For the determined ALR values, Nusselt numbers decreased as the fin height increased. It was concluded that Nusselt numbers tended to decrease at all fin widths as the ALR value increased. In addition, considering the parameters examined for the rectangular-finned heat sink, separate correlations were developed for the Nusselt number, spray angle, and jet thickness.