An experimental heat transfer investigation of using spacer in direct contact membrane distillation

Abstract

Membrane distillation (MD) is a thermally-driven separation technology that can produce highly pure water. Direct contact membrane distillation (DCMD), where both hot and cold solution is directly in contact with the hydrophobic membrane is the most studied system due to its condensation method without an external condenser as well as its overall structural simplicity. In this paper, heat transfer analysis was carried out in DCMD experimentally to investigate how the presence of a spacer can effect on heat transfer coefficient. Results revealed that the heat transfer coefficient for spacer-filled channels (plastic and metallic material) is approximately from 3 to 3.5 times higher than that for empty channels. Additionally, from specific pumping power (SPP) for 1 cubic meter of freshwater production, it is predicted that DCMD with spacer-filled channels can consume far less electrical or mechanical energy than that with empty channels.