A new model for two-phase flow in a solar still improved by a porous layer

In this research, the volume of fluid (VOF) model is used to simulate the vapor-liquid two-phase flow in a single slope solar still. This model has an ability to track the interface between liquid and vapor phases during the phase change. To benchmark the accuracy of VOF model, the numerical results are compared with the experimental data and the results of previous model for simulating solar still (moist air model). It was found that the volume of fluid model predicts the experimental data with more accuracy in comparison with the moist air model. After simulation, the effect of using a sponge layer as the cheap porous material on productivity of the solar still is investigated. Sponge layer provides more effective area for evaporation and solar radiation absorption inside the solar still. Moreover, this material has wick property and transfers the water to evaporation surface. The results showed that the productivity of the solar still enhances about 10% by using a sponge layer with porosity of 0.6. Moreover, it is observed that the productivity increases with decreasing the porosity of sponge layer for porosities higher than 0.6, while the productivity decreases with decreasing the porosity of sponge layer for porosities less than 0.6.