Theoretical and experimental analysis of multi-effect air gap membrane distillation process (ME-AGMD)

Abstract

A novel multi-effect air gap membrane distillation (ME-AGMD) module successfully developed for the purpose of water treatment. The mathematical model of the single stage air gap membrane distillation (AGMD) process was developed and applied to the four stage ME-AGMD unit. The performance of the AGMD and ME-AGMD process at different operating parameters such as feed temperature and flow rate, coolant temperature and flow rate, and air gap thickness is presented. Experimental results were compared with the model predicted results and validated the ME-AGMD model. The model predictions are within the ±9% of the experimental data except the effect of the cooling water temperature parameter. The maximum permeate flux of ME-AGMD was achieved about 166.38L/m2 h at the feed temperature of 80°C, feed flow rate of 1.5L/min, coolant temperature of 20°C, coolant flow rate in each cooling channel of 0.75L/min and air gap thickness of 5 mm. The flux of ME-AGMD module was found to be 3.2–3.6 times larger than the single stage AGMD module. Also the effect of feed bulk temperature on the mass and heat transfer coefficient and thermal efficiency of the module was studied and presented the results. The ME-AGMD module found the maximum thermal efficiency than the AGMD module.