Experimental and numerical study on filmwise condensation of pure propane and propane/methane mixture

Abstract

The condensation process of pure propane and propane/methane mixture on the vertical plate were experimentally and numerically researched to clarify the condensation characteristics at the first stage of natural gas liquification. In this work, a visualization experimental system was designed to study the flow pattern and heat transfer characteristics of propane vapor condensation on the vertical plate. The condensate film on the plate is wave laminar flow on the experimental conditions of liquid film Reynolds number from 59 to 321. With the increase of the liquid film Reynolds number, the flow patterns turn from straight isolated waves (about 8-10 mm length) to dense and short waves, which enhances the condensation heat transfer coefficient. At the same time, a 2-D numerical model was proposed to reveal the condensation mechanism of propane and propane/methane mixture with different wall subcooled temperature (5-40 K) and methane mole fraction (80%-95%). The numerical results agree well with the experimental data. And the results show that 80% methane reduces the liquid film thickness approximately by half comparing with the pure propane. The increase of methane mole fraction could reduce the liquid film thickness, but its contribution to the heat transfer is negligible compared with the mass diffusion resistance caused by the gas boundary layer. The heat transfer coefficient decreases beyond ninety percent compared with pure propane at the methane mole fraction of 80–95%.