On the quantification of microlayer contribution toward bubble growth under subcooled flow boiling regime

Subcooled nucleate flow boiling encompasses intricate simultaneous condensation and evaporation processes. It involves thin liquid microlayers trapped beneath growing bubbles, enabling high heat and mass transfer with fluxes exceeding 1 MW/m2. Understanding microlayer contribution to bubble growth is pivotal for developing reliable boiling models. Unlike previous studies, we account for condensation effects, important in the context of subcooled boiling regime, in estimating microlayer contribution by simultaneously obtaining microlayer dynamics from thin-film interferometry and whole-field temperature from rainbow schlieren deflectometry. We establish that the microlayer evaporation significantly influences bubble growth in flow boiling, contributing up to 60% (in growth phase) in the present study.