Experimental Investigation of Flow Boiling Regimes in a Horizontal Heated Pipe

Abstract

Many industrial applications rely on heat transfer processes when a fluid is boiled. Research on boiling and flow boiling has been of paramount interest since the 40s but despite this fact, the physical mechanisms controlling the heat transfer process remain under scrutiny. In the case of flow boiling inside pipes, three regimes have been distinguished, namely convective flow boiling, nucleate flow boiling and a liquid deficiency boiling regime. At low heat fluxes and low working pressure, convective flow boiling is dominant, and the heat transfer coefficient depends on the mass flux and the thermodynamic quality. At high heat fluxes and high pressures, nucleate boiling is dominant, and bubbles produced at the wall are attributed the control of the heat transfer. In addition, experimental studies have shown that increasing the heat flux during flow boiling can led to a limiting value of the heat transfer coefficient before the boiling crisis. These three regimes have been the focus of diverse experimental studies. In this work, we focus on experimentally isolating working conditions where only one dominant mechanism play a dominant role. This work provides a new experimental framework for studying each heat transfer regime individually.