An Experimental Study of the Enhancement of Air-Cooling Limits for Telecom/Datacom Heat Sink Applications Using an Impinging Air Jet

Abstract

An experimental study was conducted to investigate the heat transfer from a parallel flat plate heat sink under a turbulent impinging air jet. A horizontal nozzle plate confined the target surface. The jet was discharged from a sharp-edged nozzle in the nozzle plate. Average Nusselt numbers are reported for Pr=0.7, 5000⩽Re⩽30,000, L∕d=2.5, and 0.833 at H∕d=3 where L, H, and d define the length of the square heat source, nozzle-to-target spacing, and nozzle diameter, respectively. Tests were also conducted for an impinging flow over a flat plate, flush with the top surface of the target plate. The average Nusselt numbers from the heat sink were compared to those for a flat plate to determine the overall performance of the heat sink in a confined impingement arrangement. The experimental results were compared with the numerical predictions obtained in an earlier study. Although the average Nusselt numbers obtained from numerical simulations differed from the experimental measurements by 18%, the disagreement is much less significant when related to the junction temperature. Under typical conditions, it was shown that such discrepancy in the Nusselt number lead to an error of 6% in the prediction of the junction temperature of the device.