Abstract
This paper presents a study for energy requirements of lab-scale membrane distillation (MD) unit. This lab unit consists of flat-sheet membrane module with two circulation pumps, heater, and cooler to study the effect of different operating conditions on both specific energy consumption (SEC) and energy efficiency (ηE) via vacuum enhanced direct contact MD method. The flux and the two parameters of energy (SEC, ηE) were measured using different temperatures, different feed flow rates, and different feed salt concentrations. The two membranes used were neat polypropylene (PP) membrane and PP/multi-walled carbon nanotubes (MWCNTs) composite membrane. The membranes were synthesized via phase inversion process, using xylene as a solvent, methyl iso-butyl ketone as a coagulant and dispersion medium for MWCNTs. The results showed that the highest ηE was 39.5 with SEC 1,649.2 kW h/m3 at flux 52.5 kg/m2 h using 15 L/min feed flow rate of synthetic feed water with salt concentration 10,000 ppm at 55°C feed temperature. On the other hand, using our prepared membrane for the desalination of oil field water, the values of ηE and SEC were 12.1 and 4,189.5 kW h/m3, respectively.
Acknowledgements
It is a pleasure to acknowledge the financial support provided by the Science and Technological Development Fund (STDF) in Egypt through Grant 5240 (Egyptian Desalination Research Center of Excellence, EDRC).