Large area spray cooling by inclined nozzles for electronic board

To cool a 1 kW 6U electronic card, an innovative inclined spray chamber with multiple nozzles has been developed and investigated with a closed-loop refrigeration system. A large heated surface (12.3 × 15.5 cm²) was sprayed by four gas-assisted nozzles with an inclined angle of 39° relative to the normal direction. A reasonable spray coverage area can be obtained by the inclined spray chamber while enabling a relatively lower spray chamber height than that required by a normal spray chamber. R134a was implemented as the working fluid in this study. The mass flow rate, pressure drop across the nozzles, and the spray chamber pressure were varied experimentally, and the results suggest that the increases of the mass flow rate, the pressure drop across the nozzles, and the spray chamber pressure can improve the thermal performance of the inclined spray. The average heated surface temperature can be maintained within 20.0°C, and the maximum heat transfer coefficient of 4742.2 W/m^2·K can be achieved at a suitable working condition.