High-efficiency spray cooling of electronics with HFE-7100 on finned surfaces

This study investigates spray cooling of HFE-7100 using full-cone nozzles, with varied fin heights (1.0, 1.5 and 2.0 mm) and mass flow rates (3.5, 4.5 and 5.5 g·s⁻¹). Straight fins achieved the best performance, reaching a critical heat flux (CHF) of 301 W·cm⁻² and a heat transfer coefficient (HTC) of 3.8 W·cm⁻²·K⁻¹. This corresponds to a 123 % improvement over the smooth surface. Evaporation efficiency (η) showed nonlinear dependence on fin height due to area enhancement and spray shadowing. Higher mass flow rates reduced η due to the shorter liquid residence time and increased droplet splashing. A CHF correlation based on fin geometry and spray dynamics predicted CHF within 14 % error for smooth and 28 % for finned surfaces.