Law of resistance in two-phase flows inside pipes

Abstract

Two-phase micro- and mini-channel heat sinks are attractive for removing high heat fluxes, but the pressure drop in the two-phase flow regime can lead to prohibitively too high pumping power requirements. While significant research has been performed in the last decade for understanding the physical mechanisms controlling the heat transfer phenomenon, determining the two-phase flow pressure drop inside channels remains a longstanding question. In spite of the vast research performed, no agreement has been achieved in terms of the physical mechanisms controlling the two-phase pressure drop. Here, we measure the two-phase flow pressure drop in adiabatic conditions in a mini-channel considering the influence of the working pressure. The experiments show that the density ratio of the two-phase flow mixture plays a major role in controlling the pressure drop as the liquid phase enriched in the vapor phase increases the velocity of the flow. This finding minimizes the number of dimensionless groups required for predicting the two-phase flow pressure drop and is confirmed using independent experiments from the literature.