Experimental Investigation of Boiling Characteristics of High Volatile Fluids under Varying Heat Flux Levels

Abstract

In recent years, there have been significant advances in the field of supercomputers and data centers, resulting in the generation of high heat flux levels. To effectively cool such high heat flux equipment, boiling immersion cooling has emerged as a promising solution. In the quest to enhance the heat transfer performance of nucleate boiling through passive means, this research focuses on exploring the boiling behavior of one of the high volatile fluids, namely dichloromethane (DCM). To investigate the nucleate boiling phenomenon of DCM, pool boiling experiments were conducted within a closed vessel at atmospheric pressure. Three distinct levels of heat flux were applied (58, 76, and 95 kW/m 2 ) to observe its impact on bubble dynamics. The experimental setup employed high-speed rainbow schlieren deflectometry to simultaneously map the dynamics of vapor bubbles while varying the heat flux levels. The results obtained from the experiments demonstrated a strong correlation between heat flux and various bubble characteristics. Specifically, the bubble mechanism, including bubble departure frequency, bubble diameter, waiting time, and forces acting on bubble, exhibited notable changes in response to variations in heat flux levels. By studying the bubble dynamics, it was observed that as the heat flux increased, the frequency at which bubbles departed from the heated surface decreased. Additionally, the bubble diameter was found to increase at higher heat flux levels. Furthermore, the waiting time, representing the duration between bubble departure and the subsequent bubble formation, as well as the various forces acting on bubble were also seen to be strongly influenced by the applied heat flux.