The Numerical Simulation of Liquid-Vapor Stratified Flow in Horizontal Metal-Foam Tubes.

Abstract

In this paper, a boiling stratified flow model in a metal-foam tube is proposed. First, based on Branuer non-equilibrium gas-liquid interface model, a force balance on the gas-liquid interface in metal-foam is calculated. The shape of the interface of upper gas phase and lower liquid phase in metal foam tube is obtained. As for the lower liquid phase, the energy conservation equations of liquid and metal foam are formulated, which account for porosity and fiber diameter of foam on the basis of non-local thermal equilibrium model (NTEM), respectively. Therefore, a profile of temperature difference between liquid and metal foam can be obtained. For the upper gas phase, an empirical correlation developed by other researchers is utilized to obtain temperature difference between gas phase and solid wall. In addition, the variation of the Reynolds number with increasing mass quality along the flow direction is acquired. Ultimately, an average circumference heat transfer coefficient is calculated. The results of circumference heat transfer coefficient agree well with available experimental data, showing the prediction of the proposed stratified flow model is feasible. The reason resulting in discrepancies between the prediction and experiment data is also illustrated.