A semi-empirical model for two-phase heat transfer from arrays of confined impinging jets

Two-phase jet impingement is a compact cooling approach that provides high-heat-flux dissipation at manageable pressure drop. The heat transfer behavior of an impinging jet array is dependent on a set of geometrical parameters, operating conditions, and fluid properties. In the present study, a semi-empirical approach is developed to predict heat transfer from arrays of jets of liquid that undergoes phase change upon impingement. In the model, the jet array is divided into unit cells centered on each orifice that are assumed to behave identically. The impingement surface in each unit cell is divided into two distinctive regions: a single-phase heat transfer region directly under the jet, and a surrounding boiling heat transfer region along the periphery. Available correlations from the literature are used to estimate the heat transfer coefficient and surface temperature distribution in each region, and the mean surface temperature of the unit cell is estimated via area-averaging. The location of transition to boiling predicted by the model is consistent with prior experimental observations of an inward-creeping boiling front. The model results are first compared against existing experimental data in the literature, and the area-averaged thermal performance is found to be well-predicted. Additional experiments are also performed to evaluate the limits of applicability of the model. The semi-empirical modeling approach developed in this work successfully represents the different heat transfer modes and transitions that occur during two-phase jet impingement.