The analytical study of flow regime effects on methane-air mixture put inside a micro-channels with Pt catalyst surface

In this paper, an analytical analysis for thermal and mass transfer effects of a non-homogeneous catalytic mixture into a microchannel is investigated with considering flow regime effects. The importance of the present work is to find out the selective Knudsen number and investigating the possessions of mass and heat jump coefficients on the present problem. The governing equations include energy, molar fraction and catalytic conversion equations, and the effects of flow regime is introduced into the problem through boundary conditions. The obtained results are compared in three different values of the Knudsen number with experimental data. The maximum errors rather than experimental data for Knudsen number equal to 0.1 is 7.54 percent but for Knudsen numbers of 0.01 and 0.001, the errors is increased to 35.4 percent. Therefore, the selective Knudsen number for catalytic micro-channel is equal to 0.1. The greatest increase in fuel conversion with increasing Knudsen number is occurred in the low Reynolds number with a value of 35.2%. Furthermore, the increasing rates of fuel conversion and surface mole fraction with increase of Knudsen number are nearly equal, which this issue is due to entrance of fluid from continuous to slip regime.