Planar Liquid Jet Impingement Cooling of Multiple Discrete Heat Sources

Abstract

Average heat transfer measurements have been made for discrete heat sources located under a liquid jet issuing from a rectangular slot. The heat sources were flush mounted in a plane wall of low thermal conductivity, while the jet emanated from a slot in the opposite wall. The two walls formed a plane channel which simulated a multichip module cooled by direct liquid immersion. Heaters were positioned directly below the jet, as well as at locations offset from the jet midplane. The measurements revealed a secondary peak in the heat transfer coefficient at an offset of approximately four jet widths, and the magnitude of the secondary peak increased with increasing Reynolds number. Depending on Reynolds number, the secondary peak may be due to formation of a recirculation zone and/or to boundary layer transition. The effect of separation distance between the nozzle and the impingement plate was small for the conditions of the study, as was the effect of upstream heating on heat sources located near the stagnation line of the jet. The effect of the outflow manifold location was also found to be negligible, except when it was positioned directly over a heater.