Spray Cooling Trajectory Angle Impact Upon Heat Flux Using a Straight Finned Enhanced Surface Available to Purchase

Experiments were conducted to study the effects of spray trajectory angles on heat flux for flat and enhanced surface spray cooling. The surface enhancement consisted of straight fins machined on the top surface of a copper heater block. Spray cooling curves were obtained with the straight fin surface aligned both parallel (axial) and perpendicular (transverse) to the spray axis. Measurements were also obtained on a flat surface heater block for comparison purposes. Each copper block had a cross-sectional area of 2.0 cm². A 2×2 nozzle array was used with PF-5060 as the working fluid. Thermal performance data was obtained under nominally degassed (chamber pressure of 41.4 kPa) conditions. Results show that the highest CHF in all cases was attained for a trajectory angle of 30° from the surface normal. Also, straight finned surfaces can enhance critical heat flux (CHF) as much as 75% (heat flux value of 140 W/cm²) relative to the vertical spray orientation for the analogous flat surface case.   This paper was also originally published as part of the Proceedings of the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems.