The Effect of Nozzle Geometry on Pressure Drop and Heat Transfer to Free Surface Liquid Jet Arrays

Due to the current trend of miniaturization of electronic components, higher heat fluxes are encountered. Current fan cooling methods are approaching their maximum cooling capabilities leading to the investigation of liquid cooling techniques. An experimental study of the cooling capabilities of liquid water impinging jet arrays, with a view for use in the cooling of electronic chips, is presented. The 3.0 mm thick jet nozzle plate contained 45 individual jets of 1mm diameter with 5 mm spacing between each jet. The arrays impinged onto a copper surface of 31.5 mm diameter, which dissipated approximately 200 W of heat. The inlet and outlet geometries of the jets were varied with a view of determining an optimal configuration with regards to maximum heat transfer to the impinging jets for the minimal pressure drop across the nozzle plate. Each array was tested under free-surface flow conditions, with a constant jet-to-target spacing of H/d = 20 for a Reynold’s number range of approximately 300–10,000. The results indicate that chamfering of the inlet decreased the pressure drop for a given average heat transfer coefficient, whilst chamfering of the outlet provided a greater heat transfer for a given Reynold’s number.Copyright © 2007 by ASME