Parametric Investigations on Novel Cylindrical and Helical Air Gap Membrane Desalination Systems Analytical and Experimental Approach

Abstract

newline i newlineABSTRACT newlineMembrane Desalination is a non-isothermal process which is basically a rate newlinegoverned separation process. A rate governed separation process is one in which newlineseparation is based on differences in transport rate through some medium under the newlineinfluence of a driving force resulting from a gradient in pressure, concentration, newlinetemperature or electrical field. Membrane distillation provides an outstanding solution newlineto the water problems as it s cheap, efficient, requires fewer skills, economical solution newlineand safe to the environment. It involves a hydrophobic membrane such as newlinepolytetrafluoroethylene (PTFE), polyvinayleidineflouride (PVDF), polypropylene newline(PP), polyethylene (PE) etc. which allows only the vapors to pass through it but not to newlinethe liquid and other solutes. newlineIn the present research, two novel systems are developed by modifying the newlineconventional air gap membrane distillation (AGMD) configuration. In one system, a newlinecylindrical AGMD system (CAGMD) is developed by designing the basic AGMD newlinesystem in cylindrical shape with resemblance to shell and tube heat exchanger. In this newlinesystem the inner tube is considered to act as the condenser while the outer shell acts as newlinethe channel for hot feed flow. The inner tube is a condenser tube that is made hollow, newlineto provide passage for cold fluid and is made up of conductive copper material. In other newlinedesign, the CAGMD system is further modified by providing the helical fins over the newlinecylindrical copper condenser. In both the systems, hydrophobic PTFE membrane is newlineused as the separating medium. The membrane is wrapped over the cylindrical newlinecondenser and the space between the membrane and the condenser tube forms the air newlinegap. newlineDetailed theoretical model was prepared for both the systems that is validated newlineagainst the literature as well as with the experimental findings and found to be in newlineexcellent agreement. The operating parameters considered are feed temperature and newlineflow rate, cold flow rate, air gap width, length of the module, and number