Understanding of bubble growth at nucleation site using energy based non-dimensional numbers and their impact on critical heat flux condition in microchannel

Abstract

Two phase flow initiates at Onset of Nucleate Boiling, where the first bubble emerges in the downstream flow direction. Bubble nucleation and growth in microchannel heat sinks is very conspicuous phase as the growing bubble can completely block the flow cross-section area at high heat flux. Hence, microchannels are more susceptible to flow boiling instability. In this paper effort has been put to study the bubble dynamics during bubble growth at nucleation site for microchannel in terms of non-dimensional energy ratio numbers and their variation from bubble inception until departure. New non-dimensional energy ratio is also proposed, which helps in differentiating inertia controlled and thermal diffusion controlled region during bubble growth at nucleation site. Further, possible impacts of these non-dimensional energy terms on critical heat flux are discussed. © 2018 Elsevier Ltd