An Experimental Study of Two Phase Multiple Jet Cooling on Straight-Finned Surfaces Using a Dielectric Fluid

In the present study, a jet cooling device for electronics was investigated using FC-72 as the working fluid. The system temperature of jet cooling device was set at 50°C. The jets were 5 mm above the test surface, and the heated area of the test surface was 12×12 mm². The nozzle plate had 5 or 9 pores of 0.24 mm in diameter. The test surfaces included: a smooth surface and two straight-finned surfaces of either 400 or 800μm fin height, 200 or 400 μm fin thickness and gap width. The volume flow rate varied from 50 to 150 ml/min (Re = 1655 ∼ 1860). The results showed that the heat transfer performance increased with increasing flow rate, or increasing surface area enhancement ratio. The finned surface of 800μm fin height, 200μm fin thickness and gap width yielded the best performance, which is about 250% greater than the smooth surface at 150 ml/min. As a promising chip cooling solution, the thermal resistance of spray cooling on this straight-finned surface varied between 0.14 and 0.15 K/W in the range of 60 ∼ 121 W of heat input when the present jet cooling system operated at 150 ml/min. Correlations of multiple jets cooling on smooth and straight-finned surfaces have been proposed. For the data in the range of Re = 1655 ∼ 8960, Bo = 0.024 ∼ 0.389, surface area enhancement ratio (γ_A) = 2.07 ∼ 5.32, this correlation predicts 94% of the present data within ±20%.