A new hydrodynamic approach for jet impingement boiling CHF

After shortly highlighting the main features of the classical hydrodynamic theory of pool boiling critical heat flux (CHF), the present paper describes a new approach to predict CHF in the presence of a submerged liquid jet impinging onto the heating surface in saturated conditions at both atmospheric and sub-atmospheric pressure. This approach, based on the instability of liquid-vapor interfaces, has proved to be able of fitting CHF data for submerged jets as well as for electrohydrodynamic (ionic) jets. The main dimensionless parameters governing the phenomenon have been disclosed, namely the Bond number and an equivalent Froude number. Two distinct fluid-dynamic regimes have been identified, herein named velocity-prevailing and gravity-prevailing, depending on the equivalent Froude number values and the subsequent effect of vapor buoyancy on liquid-solid contacts. The developed correlations providing CHF for both regimes have coefficients of determination higher than 0.9 with respect to the available experimental data. Further development may involve the identification of dimensionless parameters and specific correlations for CHF under free-surface jets.