Assessment of dimensionless CHF correlations for subcooled flow boiling in microgravity and Earth gravity

A comprehensive review and analysis of prior subcooled flow boiling CHF correlations was conducted to identify those correlations that provide the most accurate predictions for dielectric working fluids and small rectangular flow passages found in electronics cooling applications in both microgravity and Earth gravity. Since most prior correlations were derived from water databases, only those with dimensionless form were deemed potentially suitable for other working fluids. Only a small fraction of these dimensionless correlations were found to tackle other fluids and more complicated flow and heating configurations with acceptable accuracy. These correlations were ranked relative to mean error, mean absolute error, and root mean square error. Better predictions where achieved when correlations were based on the heated diameter rather than the hydraulic diameter because of the ability of the former to better describe vapor development in subcooled flow. Two previous correlations by Hall and Mudawar provided the best overall CHF predictions for both microgravity and Earth gravity.