Numerical simulation of forced convective evaporation in thermal desalination units with vertical tubes

摘要

The subject of present study is a numerical simulation of transient solution of evaporation on upward flow in a two-dimensional vertical tubes by using the water as the working fluid. The heat transfer mechanisms are energy and mass transfer during the phase change based on volume of fluid model in commercial CFD software, with a user defined function. Operating conditions are specified in saturation temperature of water flow boiling. The physical properties of water are determined using inlet temperature and pressure system in saturation conditions. The characteristic of water flow boiling such as void fraction, heat transfer coefficient, and wall temperature distribution are investigated in the range of various heat fluxes. Due to agitation of vapor bubbles, the flow is turbulent which is simulated based on SST K-ω model and also the pressure implicit with splitting of operators pressure-velocity coupling scheme is used to improve the efficiency of calculation.