Effects of inlet operational parameters on the combined salt gradient solar pond-direct contact membrane distillation system

Abstract

This paper focuses on the performance-analysis of a combined renewable energy system/desalination unit. The renewable energy system consists of a Salt Gradient Solar Pond (SGSP) for the collection and the storage of solar energy while the desalination process uses the Direct Contact Membrane Distillation (DCMD).DCMD processes operate practically at the same range of temperatures obtained from low temperature solar pond. However, while combining DCMD unit with a solar energy source, it is necessary to investigate the effect of energy source fluctuations on the operating parameters. The large fluctuations of solar intensity throughout the day will affect the inlet feed temperature of the DCMD process which in turn affects the permeate flux. The main objective of this study is to evaluate, numerically, the effects of inlet operational parameters on the solar driven combined system for production of fresh water. A mathematical model was built to predict the production rate from the measured temperatures of the Salt Gradient Solar Pond. Coupling the heat and mass transfer, through the membrane, the model with solar energy input is mainly based on the technology of a solar pond with a salt concentration gradient. This solar technology will not really be simulated. Indeed, temperature measurements obtained from solar pond will serve as a basis inputs of the simulation. Obtained results showed that permeate flux increases with Lower Convective Zone (LCZ) temperature of the SGSP and the sundial during the day for a year, but it was less sensitive to the Upper Convective Zone (UCZ) temperature of the SGSP and to the feed water salinity.