Criteria for kinetic and mass transfer control in a microchannel reactor with an isothermal first-order wall reaction

摘要

Analytical expressions for distinguishing between different reaction and mass transport regimes in an isothermal microchannel reactor with first-order wall reaction are presented. These expressions are explicit functions of the Damkohler number (Da) and of the Graetz parameter (α Pe_m/z), as well as of the degree of mass transport control (θ) which is usually set arbitrarily. The power law addition of contributions from fully developed and developing concentration profile conditions allows a correct description for all values of α Pe_m/z. The scaling analysis suggests that the relative importance of mass transfer effects compared to reaction should be assessed by the rescaled Damkohler number Da*, defined with the correct scales for external and internal diffusion. It is also shown that a Da - α Pe_m/z parametric map is appropriate for identifying the boundaries between regimes, which can be directly calculated from the dimensionless parameters in a very convenient manner.