Numerical and experimental investigation of thermoelectric materials in direct contact membrane distillation

Abstract

The high energy penalty associated with the direct contact membrane distillation (DCMD) technology is a major challenge precluding its commercial deployment. Although DCMD requires less aggressive operating conditions than reverse osmosis (∼1 bar vs 55 bar), its throughput is way lower (∼10 L/m2-h vs 70 L/m2-h) and its energy consumption is more (∼1700 kWh/m3 vs 7 kWh/m3). One approach to improve these metrics is the use of direct thermal energy sources inside the membrane module. A Peltier device installed inside the DCMD module to provide the needed thermal energy can reduce heat exchanger losses to near zero as the Peltier device is sandwiched between the hot feed and cold permeate in a thermoelectric-DCMD system. Previous experimental results have indicated gains in performance metrics using this approach. Given these results, robust high-fidelity computational fluid dynamics (CFD) simulations validated with experiments are developed to predict the performance of the thermoelectric-DCMD module whilst conducting a parametric analysis of the operational conditions and geometrical configurations. The Peltier device’s heat transfer rates are predicted from a simple analysis using the manufacturer’s performance datasheet and used as boundary conditions for the CFD simulations.