MODELING TEMPERATURE AND SALT CONCENTRATION DISTRIBUTIONS IN DIRECT CONTACT MEMBRANE DISTILLATION | ||||
| JES. Journal of Engineering Sciences | ||||
| Article 11, Volume 36, No 5, September and October 2008, Page 1167-1188 PDF (581.18 K) | ||||
| Document Type: Research Paper | ||||
| DOI: 10.21608/jesaun.2008.118726 | ||||
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| Author | ||||
| Ali K. Abdel-Rahman | ||||
| Associate Professor, Department of Mechanical Engineering, Faculty of Engineering, Assiut University, Assiut 71516, EGYPT | ||||
| Abstract | ||||
| Modern desalination technologies, applied to seawater and brackish water, offer effective alternatives in a variety of circumstances. Because of its low energy consumption, accessible running conditions and simple maintenance, membrane distillation (MD) has become one of the cheapest technologies for seawater desalination. The membrane distillation driving force is the transmembrane vapor pressure difference that may be maintained with an aqueous solution colder than the feed solution in direct contact with the permeate side of the membrane giving rise to the configuration known as direct contact membrane distillation (DCMD). The main objective of the present study is to provide a detailed numerical analysis of the heat and mass transfer in DCMD and to offer useful basic detailed information about the nature of the process that is needed for process improvement and optimization. Moreover, the present study is carried out to investigate the effect of parameters such as the inlet temperatures of the hot and cold solutions, the concentration of the feed (hot) solution, the inlet velocity of the hot and cold solutions on the process characteristics of DCMD desalination evaluated in terms of the permeate flux and the process thermal efficiency. The direct contact membrane distillation process has been modeled as a two-dimensional coupled problem in which a simultaneous numerical solution of the momentum, energy and diffusion equations of the feed and cold solutions have been carried out with permeation taken into account. Velocity and temperature distributions inside the membrane feed and cold solution channels are obtained. Some of the principal conclusions drawn from the present study are: (1) increasing the inlet temperature of the hot solution has a major effect on the permeate flux, (2) increasing the feed water salt concentration decreases the permeate flux, (3) the inlet velocities of the hot and cold solutions have a relatively strong effect on the permeate flux. | ||||
| Keywords | ||||
| Distillation; Direct contact membrane distillation; Modeling; Temperature polarization; Concentration polarization | ||||
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