Sub-Atmospheric Mini-Jet Impingement Boiling of Water Under Saturated and Subcooled Conditions

An experimental study of mini-jet impingement boiling is presented for saturated and subcooled conditions. Unique to this study is the documentation of boiling curves of submerged water jet impingement under sub-atmospheric conditions. Data are reported at a single sub-atmospheric pool pressure of 0.176 bar and for a fixed nozzle-to-surface distance of six jet diameters. A mini nozzle is used in the present study with an internal diameter of 1.16 mm. Jet impingement boiling at Reynolds numbers in the range of 0 to 6,800 are characterized and contrasted for both saturated and subcooled conditions. Enhancements in critical heat flux with increasing Re are observed for both saturated and subcooled conditions, with the subcooled condition of 17 °C showing approximately 2.3 times the critical heat flux as that observed for saturated conditions. Critical heat flux for subcooled jet impingement boiling is well predicted from the saturated critical heat flux data by a modified subcooled pool boiling CHF correlation presented by Inoue et al. [1]. The effect of surface finish on pool boiling is also reported.