Abstract
Pressure-driven condensing flow through a porous medium which is initially subcooled below the saturation temperature at a given back pressure is investigated experimentally and analytically. The experimental results show that condensation occurs mostly in the form of a water slug accompanied by the stepwise change in temperature at its back interface even when the ratio of the inlet to outlet pressure is rather small. An analysis is carried out using the generalized Darcy law incorporated with the concept of relative permeability. It is then found that the initial subcooling significantly amplifies the slug growth rate and reduces the slug velocity due to the increase in the upstream pressure drop which is caused by the increased vapor flow rate. Comparison between the experimental and analytical results shows a fairly good agreement for porous media with small characteristic dimensions.
