Nozzle to plate optimization of the jet impingement inlet of a tailored-width microchannel heat exchanger

• A hybrid jet-impingement/microchannels cooling system is experimentally studied.
• The nozzle geometry impact on the performance of the cooling device is assessed.
• The optimum nozzle to plate spacing (z/b) varies with the coolant flow rate.
• Temperature uniformity, thermal resistance and pressure drops vary differently with z/b.
• The design procedure may weight up the above cited parameters.

This work presents an experimental study on the effect of the nozzle geometry on the performance of a hybrid jet-impingement/microchannels cooling system. The proposed heat sink is designed so as to maintain the temperature of the cooled surface uniform, even with the coolant flow temperature increasing along the flow path. Previous results showed quite uniform temperature distributions with the exception of the zone located just below the jet impingement, where the temperature is higher. In the present work, several nozzle to plate spacings (z/b) are experimentally studied. The impact of nozzle to plate spacing on the stagnation point Nusselt number and the overall temperature distribution varies as a function of the coolant flow rate. A strong coupling between the slot jet geometry, the heat exchange in the varying width microchannel sections and the flow regime is demonstrated. The global thermal resistance, the temperature uniformity and the pressure drops show distinct behavior as a function of the nozzle to plate spacing, implying that the design procedure may weight up these parameters according to the cooling needs.