SOLAR DRIVEN MEMBRANE DISTILLATION UNIT

Abstract

Solar powered distillation is an attractive method for producing clean water in remote areas. The basic objective of this work is to prepare a small scale standalone system for the production of fresh water. A closed loop distillation system based on direct contact membrane distillation (DCMD) is developed and then it is integrated with solar collector. All the energy requirements for the system are met by solar collector. A mathematical model is developed which is dependent on heat and mass transfer within the DCMD module in order to predict the effectiveness of the system under different working parameters. Poiseuille and Knudsen model is used for this purpose which is then solved using MATLAB® software numerically. The verification of model is done by means of parametric analysis. This proposed model is then used to figure out the temperature difference across the both surfaces of hydrophobic membrane which then led to the calculation of pressure difference across the membrane which then led to the result of permeate flux. The results of mathematical model are then verified through simulations by using COMSOL® software and the optimum working conditions for the system are identified. Also the modelling of solar collector is done to evaluate the temperature of fluid after the process of heating from Sun. This also became the basis of MATLAB® code which demanded evaluation of versatile coefficients for various reasons. A small scale working prototype is also developed in order to validate the theoretical results. From experimentation, it is observed that the water flux increases with increasing the bulk feed temperature, bulk feed velocity, porosity of membrane and decreases with increasing the bulk permeate temperature, decreasing the bulk permeate velocity, increasing the membrane thickness etc