Performance Investigation of O-Ring Vacuum Membrane Distillation Module for Water Desalination

Adnan Alhathal Alanezi,Adnan Ahmad,E El-Zanati,H Abdallah,Adel O Sharif

doi:10.1155/2016/9378460

Abstract

A new O-ring flat sheet membrane module design was used to investigate the performance of Vacuum Membrane Distillation (VMD) for water desalination using two commercial polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) flat sheet hydrophobic membranes. The design of the membrane module proved its applicability for achieving a high heat transfer coefficient of the order of 103 (W/m2 K) and a high Reynolds number (Re). VMD experiments were conducted to measure the heat and mass transfer coefficients within the membrane module. The effects of the process parameters, such as the feed temperature, feed flow rate, vacuum degree, and feed concentration, on the permeate flux have been investigated. The feed temperature, feed flow rate, and vacuum degree play an important role in enhancing the performance of the VMD process; therefore, optimizing all of these parameters is the best way to achieve a high permeate flux. The PTFE membrane showed better performance than the PVDF membrane in VMD desalination. The obtained water flux is relatively high compared to that reported in the literature, reaching 43.8 and 52.6 (kg/m2 h) for PVDF and PTFE, respectively. The salt rejection of NaCl was higher than 99% for both membranes.

Highlights

Fresh water shortages and water scarcity are major global issues, especially in the arid and semiarid regions of the world, where fresh water can be obtained through different techniques, such as the desalination of seawater
The results show that the water flux decreases as the NaCl concentration increases due to the reduction of the vapor pressure difference, which decreases the amount of water vapor flowing across the membrane
The results showed that the membrane module design proved its applicability for achieving a high heat transfer coefficient hf of the order of 103 (W/m2 K) and high Reynolds number (Re)

Summary

Introduction

Fresh water shortages and water scarcity are major global issues, especially in the arid and semiarid regions of the world, where fresh water can be obtained through different techniques, such as the desalination of seawater. Desalination is one of the earliest methods known to man of obtaining saltfree water. In nature, it forms the source of the hydrological cycle. More than 80% of the world’s desalination capacity is provided by two processes: multistage flash (MSF) and reverse osmosis (RO) [7]. These technologies are energy intensive, with the energy mainly supplied by fossil fuel sources, and are not linked to renewable energy sources. During the MD process, a hot saline solution is brought

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