Computational investigation of single and multi-jet array impingement boiling

Abstract

Jet impingement boiling has been studied extensively and has been identified as one of the most promising thermal management techniques for high heat flux applications. Unfortunately, only a few numerical studies have been reported in literature and they are mostly limited to single jets. In the present study, both submerged single round jets and confined multi-jet arrays are investigated numerically, using the Eulerian multiphase framework with the Rensselaer Polytechnic Institute (RPI) boiling model to predict heat transfer. The numerical results of the single jet case correlate well with reported experimental data and previously reported numerical results. The numerical results of the multi-jet array correlate well with experimental data reported in the literature, proving that the RPI boiling model can successfully predict the heat transfer of jet array boiling. The effect of conjugate heat transfer in jet impingement boiling heat transfer is also investigated for both single and multiple jet cases. The single-jet results agree with previous reported numerical studies. To improve numerical convergence, especially for higher heat fluxes, use was made of a hydrostatic pressure gradient at the outlet. This allowed for significant improvement in the convergence of the continuity equation. Finally, parametric analyses were conducted for both single and multi-jet arrays in the fully developed nucleate boiling regimes. Parameters included jet-to-surface spacing, Reynolds number and subcooling. The results for the single jet correlate well with the observations of experiments reported in the literature. The results for the multi-jet array showed less sensitivity to changes in jet velocity at low jet-to-surface spacing than the single-jet case. Both single and multi-jet cases showed that reducing the subcooling resulted in an onset of nucleate boiling at lower heat fluxes and that the boiling curve shifted to the left in the nucleate boiling regime.