Numerical Modeling of Liquid-to-Vapor Phase Change in Porous Medium Under Solar Heat Localization

Abstract

Evaporation process is a crucial part of many fundamental industrials and medicals process. This paper numerically model a novel method of steam generation and enhanced evaporation using solar thermal energy. In this model, a capillary-raised fluid flows through a porous medium under localized heating condition, and the phase change from liquid to vapor at the liquid-vapor interface occurs. The hydrophilic porous material facilitates the capillary forces for better transportation of the bulk water through the porous media to the surface of porous media where the absorbed solar energy deliver to the amount of water inside the pores. The high capillary force due to the micro size inter connected pores inside the medium will rise the fluid from the cold bulk reservoir and the highly concentrated solar radiation focused inside the medium will evaporates the liquid very effectively. Based on this approach, the absorbed solar energy is delivered into the specific small pores of porous media that initiate the localized evaporation process. The steam generated from this economical technique could be used greatly for thermal solar desalinations process, sterilization process, etc. A CAD model of such porous media was developed using SolidWorks package. The mesh will be generated on the CAD file and the model was imported into the ANSYS Fluent for solving the governing equations. The mass transfer along with the fluid flow and heat transfer then solved. The simulations were done under different conditions including the hour distribution of irradiation in an average summer day and winter day to estimate steam generation rate. Produced vapor were from 13.96 kg/m2 to 18.95 kg/m2 in typical summer and winter days, respectively. The results show a temperature changes between 26.9°C and 54.4 °C. Development of the 3D numerical model and its implementation in existing data facilitates better understanding of the transport phenomena through the porous media.