Simulation of natural convection boiling heat transfer for refrigerant R-134a flow in a metal foam filled vertical tube

Abstract

Natural convection boiling heat transfer for Refrigerant R-134a flow in a metal foam filled vertical tube is numerically investigated in the present work by using the Multiphase Mixture Model MMM at constant heat flux for both transient and steady state behavior under different parameters. The effect of changing imposed heat flux, porosity, PPI (pore per inch), and tube diameter was analyzed. It is found that liquid saturation will reach its minimum value at the exit, and the dry out point will be seen always at the 2nd half of the tube length. Results also show that smaller tube diameter and higher porosity for the same PPI caused a higher temperature variation over the entire metal foam tube. Comparisons with previous works show good agreement. Keywords: Metal foam, Natural convection, Boiling, Multiphase mixture model, Vertical tube