Spatio-temporal temperature distribution and heat transfer analysis during subcooled nucleate pool boiling on plates

Abstract

Nucleating bubbles contributes to improved heat transfer during the liquid–vapor phase transition and becomes beneficial in confined spaces where substantial energy transfer is necessary. The study is conducted to analyse the heat transfer mechanism and associated bubble behaviour during nucleate boiling at subcooled condition. The analysis is performed on horizontally oriented plates under ambient conditions. The temperature distribution over the plates at given heat flux is visualized using non-invasive IR thermal camera. The captured thermal images were initially analyzed to comprehend the impact of subcooling on different stages of the boiling process. It encompasses free convection from the surface, isolated heterogeneous nucleation, and the vertical agglomeration of detaching bubbles. The study gives an ideation to introspect the wall heat flux regime during subcooled pool boiling. Various phenomena associated with subcooled pool boiling, for instance, bubble ebullition, subcooling effect on heat transfer is discussed. The gradual shrinkage of bubble in the liquid pool is observed. The analysis of subcooled nucleate pool boiling on plates revealed intriguing insights into the spatio-temporal temperature variations, showcasing distinct patterns at different heat flux levels. Additionally, the study delved into the intricate wall heat flux partitioning among various boiling regimes, shedding light on the dynamics of bubble ebullition under subcooled conditions. An empirical correlation is suggested for predicting convective heat transfer coefficient for the subcooled pool boiling.