A mechanistic model for predicting the maximum diameter of vapor bubbles in a subcooled boiling flow

•A mechanistic model of maximum bubble diameter for subcooled boiling is proposed.•A lumped energy balance approach is employed to derive the new model.•The contribution of relaxation microlayer to bubble growth is significant.•Evaporation microlayer is almost depleted during the latter phase of bubble growth.•The new model closely matches the experimental data of subcooled boiling flows.