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A computational fluid dynamics (CFD) approach to modeling of pervaporation in thin membrane channels

Soltanieh, M ; Sharif University of Technology | 2006

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  1. Type of Document: Article
  2. Publisher: 2006
  3. Abstract:
  4. A comprehensive model for pervaporation in thin membrane channels was developed to study the effect of changing temperature and concentration on mass flux. This model consists of momentum, energy and species mass balances along and across the membrane in the flow channel. A computational fluid dynamics (CFD) code was written in C++ programming language to solve the coupled non-linear transport equations in the channel by finite volume method. The Semi-Implicit Pressure Link Equation (SIMPLE) CFD algorithm is used to modify the dependent variables in each of the iterations. The effect of variation of temperature and concentration on transport and thermodynamic properties were considered by using the appropriate property models. As a case study, in this paper property parameters for ethanol/water mixture were considered. Due to the steep gradients near the membrane, a variable non-uniform mesh was used for numerical calculations with higher mesh densities near the walls. The results have been verified by similar but simpler classical problems such as semi-empirical dimensionless correlations for Sherwood number based on the Leveque approximation. These results show that the effect of temperature reduction on membrane mass flux in the feed side of membrane is very important. It is shown that the average flux of membrane is multiplied by a factor 2.3 and 4.5 when temperature changes from 30° to 45° C and from 30° to 65° C, respectively. For feed temperature of 30°, 45° and 65° C, the reduction of water concentration at the membrane surface at the end of the channel, relative to the inlet concentration of the water is 8, 14 and 24%, respectively. Temperature polarization causes a non-linear reduction of mass flux, which is due to the non-linear variation of vapor pressure and diffusion coefficient of species with temperature. In contrast, the effect of concentration on mass flux is usually considered to be linear. The mass flux depends on the feed temperature, feed flow rate and membrane properties
  5. Keywords:
  6. Algorithms ; C (programming language) ; Computational fluid dynamics ; Flow rate ; Mass transfer ; Leveque approximation ; Temperature reduction ; Thin membrane channels ; Pervaporation
  7. Source: CHISA 2006 - 17th International Congress of Chemical and Process Engineering, Prague, 27 August 2006 through 31 August 2006 ; 2006 ; 8086059456 (ISBN); 9788086059457 (ISBN)