Optimal geometry of catalytic microreactors: Maximal reaction rate density with fixed amount of catalyst and pressure drop

In this paper, the dimensionless reaction rate density of a two-dimensional channel with catalyst on its boundary was maximized by optimizing its aspect ratio H/L. Order of magnitude expressions in the limit of small H/L and in the limit of large H/L were developed and then intersected to predict the optimal aspect ratio and maximum reaction rate. Numerical simulations were performed and the results corroborated very well with the scale analysis. The results showed that the optimal design of microreactors depends on the Schmidt number (Sc), the Bejan number (Be) and the Catalyst number (Ct). Correlations based on those numbers are proposed. The analysis was performed for steady-state laminar flows, using the dilute species assumption and a first order kinetic expression.

► The reaction rate of a microreactor is maximized by optimizing its geometry.
► The reaction rate showed three distinct behaviors depending on the value of H/L.
► Expressions for the optimal geometry are obtained by scale analysis and CFD.
► Two kinds of optima are identified: large Ct and small Ct optima.
► Correlations are now available for estimating optimal microreactor geometry.