Dilute binary water-glycerin mixture for enhancement of pool boiling critical heat flux

Improving the critical heat flux for boiling heat transfer has long been the goal of both academia and industry. We were very surprised to find that adding a small amount of glycerin to water, forming a dilute binary water-glycerin solution, can significantly enhance the critical heat flux of pool boiling. Unfortunately, the classical critical heat flux model of mixture cannot provide an ideal prediction in this situation. After we review these theories in literature, we found that the Marangoni effect, a factor that was previously considered to have a dominant influence, becomes no longer significant because of the close surface tension between water and glycerin. Then, the CHF enhancement mechanism is tried to analyze considering the microlayer behavior. The dilute glycerin solution concentrates during evaporation of the microlayer. The high glycerin concentration prevents the microlayer from being completely evaporated, and its high viscosity retarded the receding of contact line and inhibited the expansion of dry spots. We proposed a CHF model based on percolation theory which can provide an ideal predictive ability for this kind of CHF enhancement. The results of this article provides a new perspective for raising boiling critical heat flux in future research. © 2025 Elsevier Ltd