Thermal Management of Power Inverter Modules at High Fluxes via Two-Phase Spray Cooling

A spray cooling system was developed and tested for thermal management of power inverter modules utilized in automotive applications. The system featured an array of 1×2 pressure atomized nozzles that used 88°C boiling point antifreeze coolant with 0.15-l/min.cm² liquid flow rate and 145-kPa pressure drop. A 2-cm² simulated device, having two kinds of enhanced spray surface with microscale structures, reached up to 400-W/cm² heat flux with as low as 14 °C surface superheat. These experimental results demonstrated the capability of greatly reducing the overall thermal resistance of the inverter modules that are commonly cooled with single-phase convective systems. The long-term reliability of the spray cooling was assessed with 2000 h of testing time. Performance of the presented system proved the spray cooling of power electronics as an attractive option that enables high power densities while maintaining acceptable and uniform device temperatures. In addition, due to the use of high temperature coolant at low flow rates, the spray cooling offers a compact and efficient system design.