Experimental and 3-D Numerical Heat Transfer Analyses of Dual Spray Water Nozzle Impingement on a Flat Plate

Abstract

Spray impingement cooling is the major method currently used to cool steel after the hot-rolling process. In this study, dual nozzles are used to investigate the cooling character of the flat plate using for the spray impingement cooling process. Based on an experimental temperature measurement, a three-dimensional numerical model is set up to calculate the transient heat transfer coefficient of the cooling plate by solving the inverse heat conduction problem with the conjugate gradient method. Both the experimental and numerical results indicated that an interference region appeared between the two jet spray impingement regions. The interference pitch varied with the flow rates, the height from the plane to the jet outlet, and the distance between the two jets. As water spread over the plate, the heat dissipation region gradually stretched from the impingement region to the interference and flow regions. A peak in the heat flux curve was observed when the water arrived at the wet front of the flow. Meanwhile, the peak in the heat flux decreased as the distance from the impingement region increased. A maximum local heat transfer coefficient 23,000 W/(m2K) was observed in this experiment. The global average heat transfer coefficient increased with increases in the water flow rate, but it decreased with increases in the pitch.