Experimental and Numerical Investigation of the Effect of Heater Parameters on the Onset of Nucleate Boiling From Suspended Strip Heaters

Abstract

Abstract. The point of onset of nucleate boiling (ONB) is the transition point from convection to boiling. Understanding the variation in ONB with heater parameters, namely, heater width, thickness, material, and subcooling, will help in the effective design of heat transfer systems. The present study aims to develop an understanding of ONB as a function of different heater parameters. An experimental investigation was carried out to determine the effect of heater widths and thicknesses for different material strips, namely, stainless steel 316 (SS 316), nickel, and copper. The main finding of the study is that, with a decrease in heater width, there is a nonlinear increase in the heat flux and wall superheat at ONB. A supplementary computational fluid dynamics (CFD) investigation has been done to understand this behavior, and it is concluded that the variation in the thermal plume movement resulted in the change in average strip temperature. Smaller width strips had relatively stable plumes that completely engulfed the heater, whereas the thermal plume for larger heaters had higher movement and allowed cooling from the sides, resulting in lower average heater temperatures. The heater temperature at ONB is found to be lower for strips with materials having higher conductivity and thickness. The reduction in the lateral thermal resistance is found to be the contributor to this observed decrease. A correlation is arrived at that takes into consideration the effect of heater parameters.