Experimental Investigation of Heat and Mass Transfer in Tubular Membrane Distillation Module for Desalination

Abstract

Membrane distillation is a thermally driven membrane process for seawater desalination and purification at moderate temperatures and pressures. A hydrophobic micro-porous membrane is used in this process, which separates hot and cold water, allowing water vapor to pass through; while restricting the movement of liquid water, due to its hydrophobic nature. This paper provides an experimental investigation of heat and mass transfer in tubular membrane module for water desalination. Different operating parameters have been examined to determine the mass transport mechanism of water vapor. Based on the experimental results, the effects of operating parameters on permeate flux and the heat transfer analysis have been presented and discussed in details.

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

“…As expected, the water flux of VMD for both membranes increases exponentially with the feed temperature. This is due to the major effect of temperature on the water vapor pressure according to the exponential Antoine equation [2,8,34]. Increasing the feed temperature decreases the feed viscosity and the thickness of the boundary layer, which significantly enhances the mass transfer coefficient.…”

“…However, these technologies are energy intensive, with the energy mainly supplied by fossil fuel sources, and are not linked to renewable energy sources. Among the recent technologies, membrane distillation (MD) has the advantage of performing at moderate temperatures and pressure [2,3,8,9]. MD process is an emerging thermally driven membrane process and can be applied successfully in desalination [10,11].…”

“…MD process is an emerging thermally driven membrane process and can be applied successfully in desalination [10,11]. The MD process is economical in terms of energy because the heat source for the process can be low grade and/or alternative energy sources such as solar and geothermal energy and because energy is continuously recovered [2,8,9,12]. During the MD process, a hot saline solution is brought in contact with a hydrophobic membrane, which allows water vapor to diffuse through the membrane, restricting the flow of liquid and hence dissolved salts through its pores [13,14].…”

“…During the MD process, a hot saline solution is brought in contact with a hydrophobic membrane, which allows water vapor to diffuse through the membrane, restricting the flow of liquid and hence dissolved salts through its pores [13,14]. The mass transfer of water vapor through the membrane pores is facilitated by the vapor pressure difference, as well as the temperature difference between the two sides of the hydrophobic membrane, that is, the feed side and the permeate side, as shown in Figure 1 [2,3,8,[14][15][16]. MD can be divided into four configurations ( Figure 2) such as (a) Direct Contact Membrane Distillation (DCMD), where the membrane is in direct contact with the cold and hot fluids, (b) Air Gap Membrane Distillation (AGMD), where an air gap is introduced between the membrane and the condensation surface, (c) Sweeping Gas Membrane Distillation (SGMD), where a cold inert gas is employed to sweep the water vapor at the permeate side to condense outside the membrane module, and (d) Vacuum Membrane Distillation (VMD), where the vacuum is applied to the permeate side by means of a vacuum pump to condense the water vapor outside of the membrane module [2,9,10,17].…”

Theoretical and experimental analysis of multi-effect air gap membrane distillation process (ME-AGMD)

“…35 Air gap membrane distillation (AGMD) is one Q3 of the four 36 common MD configurations. In AGMD, air-gap is introduced 37 between the membrane and condensation surface to reduce the 38 heat loss by conduction [13]. The latent heat can be recovered 39 during the condensation of the vapor on cooling plate in AGMD 40 configuration.…”