An experimental study of two-phase multiple jet cooling on finned surfaces using a dielectric fluid

In the present study, a multiple jet-cooling device for electronic components was investigated, using FC-72 as the working fluid. The nozzle plate, located 5 mm above the 12 × 12 mm² test surface, had 5 or 9 pores of 0.24 mm in diameter. The test surfaces included a smooth surface, two pin-finned surfaces and two straight-finned surfaces of 400 or 800 μm fin height, 200 or 400 μm fin thickness and gap width. The results showed that the heat transfer performance increased with increasing flow rate or increasing surface area enhancement ratio. The pin-finned surface of 800 μm fin height, 200 μm fin thickness and gap width yielded the best performance, which was about 250% greater than the smooth surface at 150 ml/min. Correlations of two-phase multiple jets, cooling in free and submerged states, are proposed based on the data at 50 °C saturation temperature, in the range of Re = 1655-8960, Bo = 0.024-0.389, area enhancement ratio = 1.0-5.32, jet spacing-diameter ratio (S/d) = 13.7 and 20.6. The root mean square deviation of the prediction is 11.96% for the free jet data, and 9.08% for the submerged jet data. Thermal resistance of the best surface varied between 0.1 and 0.13 K/W at 150 ml/min flow rate in the range of 60-120 W heat input.