ISSN Online: 2688-7231
ISBN Online: 978-1-56700-524-0
Proceedings of the 26thNational and 4th International ISHMT-ASTFE Heat and Mass Transfer Conference December 17-20, 2021, IIT Madras, Chennai-600036, Tamil Nadu, India
Investigation of Temperature Polarization in Membrane Distillation with Localized Heating in Feed Channel
Membrane distillation utilizes low temperature heat to distil water across a hydrophobic membrane using vapor pressure gradient across the membrane caused by interfacial temperature difference. Temperature polarization is the major issue causing the reduction in distillate flux in membrane distillation. In this study, a membrane distillation unit has been modelled analytically for analyzing the heat and mass transfer phenomenon during localized heating of feed solution in feed channel. A Polytetrafluoroethylene (PTFE) membrane has been considered with a porosity of 0.83 along with feed water having a salinity in range of 40,000 − 50,000 ppm with channel dimensions of 100 mm × 50 mm × 25 mm. The considered feed water is a solution of NaCl dissolved in water. Increased permeate flux is observed with the inclusion of localized heating in feed channel with increase in feed and permeate temperature, salt concentration, porosity. However, the increase in flow rates causes reduction in permeate flux due to increase in heat transfer coefficients in the channels resulting in heat losses from membrane interfaces to bulk solution lowering the net driving force. It is observed that maximum 617% in permeate flux with a heating rate of 15,000 W/m2 with respect to case of no heating in feed channel.