Experimental Study of Microscale Bubble Growth and Departure Dynamic Over a Surface With Constant Heat Flux Boundary Condition

Boiling heat transfer has been the subject of research for many years, with a substantial amount of effort devoted to understanding the microscale transport processes of nucleate boiling. This information is essential to determine appropriate expressions for the boiling heat transfer coefficient. As a result, several different competing models based on the bubbling dynamics and its associated heat transfer mechanisms have been hypothesized to account for the sensible and latent heat transport and liquid motion adjacent to the heat transfer surface. Many of the early models were based on the assumptions that growth, departure and the associated pumping action of the bubbles are responsible for heat transfer during nucleate boiling. Jakob [1] and Rohsenow [2] were apparently the first to postulate that the process of growth and departure of the bubble is responsible for the induced motion of the liquid adjacent to the heat transfer, as in any single-phase convection process. Rohsenow [2] modeled the heat transfer by using bubble diameter as a characteristic length to determine a Nusselt number based on a defined Reynolds and Prandtl number. Even with the same line of reasoning, Rohsenow’s analysis resulted in a different formulation compared to Froster and Zober [3], who implemented an alternate hypothesis for the velocity of the bubble interface used in defining the Reynolds number. Other models of this nature were also proposed by Forster and Greif [4] and Zuber [5].