Thermal Design of a Spray-Based Heat Sink Integrated With a Compact Vapor Compression Cooling System for Removal of High Heat Fluxes.

This paper describes the thermal design of a compact vapor compression refrigeration system for high heat flux removal. The system operates with R-134a as the working fluid and consists of a miniature compressor, a compact condenser, and a spray-based heat sink device that combines the expansion device (an array of micro-orifices) and the evaporator into a single unit. The SPHINX (Spray Heat Sink Integrated with the Expansion Device) unit has been designed based on a phenomenological model for the critical two-phase flow in the micro-orifices and phase-change heat transfer resulting from the spray atomization/jet impingement on the heated surface. The SPHINX model was solved together with mathematical models for the other system components (compressor and condenser) in order to obtain the heater surface temperature behavior as a function of the system variables. A parametric study was performed to evaluate the effect of several design variables on the system performance. Correlations available in the literature for spray cooling and two-phase jet impingement heat transfer were analyzed and critically compared. The results indicate that a cooling unit with two compressors in parallel is capable of removing thermal loads of up to 560 W (140 W/cm2) while maintaining the heater surface temperature below 85°C. [ABSTRACT FROM AUTHOR]