Pool Boiling Inversion on Surfaces With Separate Liquid-Vapor Pathways and Enhanced Macroconvection Mechanisms

A typical pool boiling curve relating the heat flux and wall superheat is often used to quantify the efficacy of the engineered surfaces. Surface enhancements promoting nucleation activity, wicking, roughness and microlayer partitioning have shown remarkable enhancements in CHF and HTC. The boiling curve for these surfaces show an increase in wall superheat with an increase in heat flux. However, recently developed surfaces using the concept of separate liquid-vapor pathways and enhanced macroconvection have shown a reverse trend where an increase in heat flux is accompanied by decreasing wall superheats. This counter intuitive trend in the boiling curve characteristics is called as boiling inversion in this work. The macroconvection heat transfer is identified as the contributing mechanism to the boiling inversion trend. The vapor-stream induced flow transition and the impinging liquid jet characteristics is quantitatively explained through analytical models available in literature. Furthermore, two surfaces exploiting this mechanism is also demonstrated in this work which sheds light on the interplay mechanisms.