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 effective design of heat transfer systems. The present study aims towards developing 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, nickel and copper. The main finding of the study is that, with decrease in heater width, there is a nonlinear increase in the heat flux and wall superheat at ONB. A supplementary 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 stabler plume which 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 resistance is found to be the contributor to this observed decrease. A correlation is arrived at which takes into consideration the effect of heater parameters.
Anthony et al. (Mon,) studied this question.