Solar Desalination of Brackish Water Using Membrane Distillation Process

The objective of this research was to evaluate the thermal efficiency of different solar collectors as water heaters and to determine the process parameters of the membrane distillation process using a hollow fiber membrane module for brackish water desalination through experimental and process modeling studies. It was found from the experimental studies that the Sunearth© flat solar collector had the highest solar to thermal conversion efficiency and a homemade parabolic solar collector had the lowest solar to thermal conversion efficiency. An experiment of direct contact membrane distillation using hollow fiber membrane module was done to purify brackish water and saline water of high salt content. The salt rejection rate obtained was approximately 99%. Modeling of heat and mass transfer phenomena associated with the membrane distillation process was also performed. The process parameters like temperature polarization coefficient (TPC), heat transfer coefficient, membrane distillation coefficient (MDC), vapor pressure polarization coefficient (VPC), and permeate stream mass flux have been obtained by modeling calculation. The calculated value of permeate stream flux was then compared with experimental results to check the consistency of the data obtained in this process. The calculated and experimentally obtained mass flux with operating temperature showed a similar behavior, which is desired for an effective direct contact membrane distillation process.