AIR GAP MEMBRANE DISTILLATION SYSTEMS WITH A TUNED THERMAL CONDUCTIVITY

Document Type

Conference Proceeding

Publication Date

2022

Department

Department of Mechanical Engineering-Engineering Mechanics

Abstract

Air gap membrane distillation (AGMD) is considered a promising low-temperature thermal-membrane separation process. Current AGMD systems employ polymeric membranes to enable the membrane-based brine evaporation process. However, the low thermal conductivity of polymeric membranes reduces the temperature gradient within the feed stream at the feed-air menisci, thereby lowering permeate flux of AGMD systems. In this study, a membrane separator with a tuned thermal conductivity is introduced to address the above shortcoming. At the feed side of the membrane separator, a high thermal conductivity porous copper interface was employed to reduce the temperature gradient at the liquid-vapor menisci. At the air side of the membrane separator, a low thermal conductivity porous polymer interface was utilized to decrease heat transfer from the feed to the permeate side. The effect of the proposed membrane separator on permeate flux under different operating parameters is experimentally evaluated. Results showed that the proposed membrane separator efficiently transfers thermal energy to the liquid-vapor menisci, thereby improving the distillate flux. The new membrane separator showed a permeate flux of 8.04 kg/m2-h at a hot inlet temperature of 80ºC, a 40.3% improvement compared with a standard polymeric membrane. The insights gained from the present study suggest new concepts for the design of commercially viable high-performance AGMD systems.

Publication Title

Proceedings of the Thermal and Fluids Engineering Summer Conference

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