APPROXIMATE ISOTHERMAL GLOBAL EFFECTIVENESS FACTOR APROXIMACION ISOTERMICA DEL COEFICIENTE GLOBAL DE EFECTIVIDAD

An approximate method to evaluate global effectiveness factor has been developed. It results from the inclusion of external mass transfer in an earlier method, which considered intraphase effectiveness factor estimations. The method, based on the approximation of the reaction rate above the surface concentrations, requires only the solution of an algebraic equation, instead of solving the differential one that defines the original diffusion reaction boundary value problem. The method can be applied to any kinetic expression. For the second order example presented, the error of the approximate global effectiveness factor with respect to the exact values is less than 15 % and turns asymptotic as the Thiele modulus becomes large.