HEAT AND MASS TRANSFER DYNAMICS IN THE MICROCHANNEL ADSORPTION REACTOR

Author： Fedorov Andrei G. Viskanta Raymond

ISSN： 1091-7640

Source： Microscale Thermophysical Engineering, Vol.3, Iss.2, 1999-04, pp. : 111-139

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Abstract

A dynamic model for conjugate heat and mass transfer in a microchannel adsorption reactor is developed. The model is based on transient, two-dimensional, and compressible Navier-Stokes equations of motion as the governing conservation equations. Appropriate boundary conditions for the momentum, heat, and mass transfer at the channel wall in the presence of adsorption for the no-slip and slip flows are formulated and incorporated into the generalized single-equation-based framework for solving conjugate problems. The 500- mu m-long parallel-plate channel with spacing between walls 10 mu m and a wall thickness 2 mu m is considered as a prototype of the unit cell of the adsorption microreactor. Air is taken a carrier gas and water vapor as an adsorbable species. The flow conditions are characterized by the Reynolds and Knudsen numbers equal to 130x10-2 and 6.5x10-3, respectively. The Freundlich adsorption isotherm is utilized to specify the adsorption desorption equilibrium. The theoretical model developed is validated by comparing the predictions with available theoretical results and experimental data for similar systems. The analysis provides new insights and fundamental understanding of the complex physics of dynamic interactions between heat and mass transfer and adsorption desorption on the microscale. The effects of different boundary conditions on the transient heat and mass transfer with and without surface physicochemical interactions are also investigated and reported.