Heat and mass transfer dynamics in the microchannel adsorption reactor

A dynamic model for conjugate heat and mass transfer in a microchannel adso rption reactor is developed. The model is based on transient, two-dimension al, and compressible Navier-Stokes equations of motion as the governing con servation equations. Appropriate boundary conditions for the momentum, heat , and mass transfer at the channel wall in the presence of adsorption for t he no-slip and slip flows are formulated and incorporated into the generali zed 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 a dsorbable species. The flow conditions are characterized by the Reynolds an d Knudsen numbers equal to 130 X 10(-2) and 6.5 x 10(-3) respectively. The Freundlich adsorption isotherm is utilized to specify the adsorption/ desor ption equilibrium. The theoretical model developed is validated by comparin g the predictions with available theoretical results and experimental data for similar systems. The analysis provides new insights and fundamental und erstanding of the complex physics of dynamic interactions between heat and mass transfer and adsorption/desorption on the microscale. The effects of d ifferent boundary conditions on the transient heat and mass transfer with a nd without surface physicochemical interactions are also investigated and r eported.