Correlations for saturated critical heat flux in microchannels

Experimental results of the saturated-flow boiling critical heat flux (CHF) in microchannels for both multi- and single-channel configurations were obtained from the literature. The collected database contains 629 data points, covering five halogenated refrigerants, nitrogen, and water, for a wide range of operational conditions, and different microchannel dimensions. The whole database was analyzed by using five empirical correlations to verify their respective accuracies. However, none of the existing correlations could predict the entire database precisely. A saturated CHF correlation was proposed by using boiling number, length-to-diameter ratio, and exit quality. Combining with the energy balance equation, the new correlation can predict the overall microchannel database accurately on the whole. It predicts almost 97.0% of the non-aqueous data (except R12 data points located in the macro-scale region) and 94.0% of the water data within the ±30% error band.