Investigation of Shell Side Heat Transfer in Cross-Flow Designed Vacuum Membrane Distillation Module

Abstract

This paper focuses on the investigation of heat transfer in a cross-flow designed vacuum membrane distillation (VMD) module. The employment of cross-flow membrane module could ensure significant reduction of temperature polarization effect at a relatively low range of Reynolds numbers. According to most literature on VMD, the heat transfer coefficients are usually estimated by the commonly used correlations for nonporous and rigid heat exchangers. However, due to the complex flow regime in module channel, the applicability of these formulas is questioned. In this work, the heat transfer in the shell side of VMD module was studied numerically and experimentally in the Reynolds range from 7.12 to 52.18. The experimental Nusselt numbers obtained in this work are relatively higher than those predicted in the literature for given conditions. The possible reasons leading to the considerable enhancement of heat transfer are analyzed and discussed.