A framework for better understanding membrane distillation separation process

Membranes and theoretical modeling of membrane distillation: a review.

https://opus.lib.uts.edu.au/bitstream/10453/30657/4/Final%20Revision_2_Unmarked%20without%20endnote%202014%2007%2028.pdf

Fouling and its control in membrane distillation-A review

Potential of membrane distillation in seawater desalination: Thermal efficiency, sensitivity study and cost estimation

Recent advances in membrane distillation processes: Membrane development, configuration design and application exploring

Novel membrane and device for vacuum membrane distillation-based desalination process

We report here direct contact membrane distillation results from modules having 0.28 m2 of membrane surface area employing porous hydrophobic polypropylene hollow fibers of internal diameter (330 μm) and wall thickness (150 μm) with a porous fluorosilicone coating on the outside surface. The brine salt concentration and temperature and the distillate temperature and velocity were varied. Water vapor fluxes approach values obtained earlier in much smaller modules. As the brine temperature was increased from 40 to 92 °C, water vapor flux increased almost exponentially. Increasing the distillate temperature to 60 from 32 °C yielded reasonable fluxes. Salt concentration increases to 10% led to a small flux reduction. An extended 5-day run did not show any pore wetting. A model using the mass transfer coefficient km as an adjustable parameter predicted the brine temperature drop, distillate temperature rise, and water vapor flux well for the large module and the smaller module of 119-cm2 surface area.

Direct Contact Membrane Distillation-Based Desalination: Novel Membranes, Devices, Larger-Scale Studies, and a Model

In the direct contact membrane distillation (DCMD) process for desalination, the water vapor flux is strongly affected by the hot brine heat transfer coefficient, conductive heat loss, and long-term flux decline due to membrane pore wetting/fouling, etc. The DCMD process has been explored here using porous hydrophobic polypropylene hollow fibers having three different dimensions and two different wall thicknesses. The outside surfaces of the fibers have been coated with a variety of microporous plasmapolymerized silicone−fluoropolymer coating. A large number of rectangular modules having the hot brine in cross flow over the outside of the fibers and cold distillate flowing in the tube side have been investigated for their DCMD performances with hot brine (1% NaCl) over a brine temperature range of 60−90 °C. The module MXFR 3 containing fibers with larger internal diameter (i.d.) and wall thickness, and having the best performance, was tested in a continuous DCMD run for 120 h with 85 °C brine flowing at a...

Novel membrane and device for direct contact membrane distillation-based desalination process

Metallic shell-and-tube heat exchangers used in thermal desalination require huge capital investments, suffer from corrosion/erosion, create heavy metal pollution, and display a large footprint. This paper has explored their potential replacement by polymeric solid hollow fiber-based heat exchangers. Using solid hollow-fibers of polypropylene (PP) (wall thickness 75 μm, outside diameter 575 μm) a number of heat exchangers were fabricated in the laboratory (heat exchange area, 195−960 cm2) and at a commercial manufacturing facility (heat exchange area, 0.15−0.44 m2). The heat transfer performances of these devices were studied for a hot brine (4% NaCl, ca. 80−98 °C)−cold water (8−25 °C) system as well as for a steam (101−113 °C)−cold water (8−25 °C) system; these systems are typically encountered in thermal desalination plants. Overall heat transfer coefficient values of as much as 2000 W/(m2 K) were achieved. This is close to the limiting value imposed by the PP wall thickness, namely, 2660 W/(m2 K). Heat...

Polymeric Hollow-Fiber Heat Exchangers for Thermal Desalination Processes

DCMD and VMD systems and methods for use in desalination applications are provided. The DCMD and VMD systems employ coated porous hydrophobic hollow fiber membranes. The coatings advantageously function to essentially eliminate pore wetting of the membrane, while permitting substantially unimpeded water vapor permeance through the fiber walls. The DCMD and VMD membranes are characterized by larger fiber bore diameters and wall thicknesses. The membranes substantially reduce the loss of brine sensible heat, e.g., heat loss via conductive heat flux through the membrane wall and the vapor space and, in exemplary embodiments, the brine-side heat transfer coefficient is dramatically enhanced by horizontal/vertical cross flow of brine over the outside surface of the coated fibers. Superior water vapor fluxes are achieved with the systems and methods.

Baoan Li

Papers

Novel membrane and device for vacuum membrane distillation-based desalination process

Direct Contact Membrane Distillation-Based Desalination: Novel Membranes, Devices, Larger-Scale Studies, and a Model

Novel membrane and device for direct contact membrane distillation-based desalination process

Polymeric Hollow-Fiber Heat Exchangers for Thermal Desalination Processes

Devices and methods using direct contact membrane distillation and vacuum membrane distillation