Spray/jet cooling for heat flux high to 1kW/cm/sup 2/

High heat fluxes from relatively small surfaces as high as to 1kW/cm/sup 2/ are needed to be removed in the cooling of microelectronic chips. Spray cooling and jet cooling with high CHF and small wall temperature rise are attractive for use. To combine the advantages of spray and jet cooling together to reach the maximum cooling capacity, the present work designed new spray head including micro nozzle array and piezoelectric plate's vibration. The experimental results point out that this is a promising method using micro nozzle array and piezoelectric plate to break bulk liquid or streams into micro droplets. In this way the diameter of liquid droplets, velocity, and their locations can easily be controlled. Spray head A has a higher heat transfer coefficient with low wall superheat by forming a stable thin liquid film on the heated surface.