An experimental study on high-pressure pulsed sprays for efficient management of high heat fluxes for moderate area devices

This work showcases an experimental sub-saturation spray cooling setup for a range of heat fluxes from 0.93 W/cm ² to 4.66 W/cm ² . The system consists of a 12” Aluminum square heat source unit with 28 embedded 1800 W cartridge heaters. An external high-pressure air tank provides the system with spraying pressures ranging from 500 to 3000 Psi. User-defined control algorithms command four piezoelectric actuated injectors allowing for the manipulation of the spray frequency, duration, duty cycle, and coordination between multiple piezo-injectors. Thus far, experiments in the horizontal configuration have shown that at 60°C, surface temperatures for all heat fluxes prove difficult to control. At 90°C, however, successful results show that heat fluxes of 1.86 W/cm ² and 2.79 W/cm ² are sustainable. Conducting experiments at aggressive power loads and surface temperatures significantly below saturation intro-duce spray-pooling, coolant pools which inhibit the evaporation rate, significantly diminishing the spray cooling efficiency. To counteract this effect, additional experiments were performed in a vertical configuration to avoid the pooling of non-evaporated coolant and enhance the heat transfer through the falling film. The results show surface temperature control for 60°C and 90°C within 6°C of the average surface temperature for heat fluxes up to 0.93 W/cm ² and 3.72 W/cm ² , respectively.