SIMPLIFIED MODELING OF RADIANT FIELDS IN HETEROGENEOUS PHOTOREACTORS .1. CASE OF ZERO REFLECTANCE

A strongly simplified model is proposed for the estimation of the radi ant flow field, and related quantities such as the local volumetric ra te of energy absorption, in heterogeneous photoreactors. The model is based on the assumption that a photon carrying energy greater than tha t of the catalyst band gap, when interacting with a catalyst particle, is invariably absorbed. The model equations allow, for simple geometr ies, analytical integral solutions to be obtained. These have the adva ntage of giving an immediate grasp on how the main physical parameters affect the radiation field: an important feature especially for engin eering purposes. The case developed here is that of a plane slab, for both monosized catalyst particles and particles with size distribution s. Notably, as no adjustable parameters are used, fully predictive res ults can be obtained. The model predictions are successfully compared with the results of original experimental tests, therefore leading to model validation. In Part 2 of this paper, another model is developed in which the assumption of zero reflectance of the particles is remove d, yet allowing analytical solutions to be obtained, One of the key fe atures of the two models is that their predictions bound the real beha vior of irradiated photoreactors, as shown in the papers. Therefore, a lthough only approximate solutions are obtained from each of the two m odels, the real behavior can be better approximated by some sort af in terpolation between the two solutions and, what is more important, con fidence limits for the final solution are obtained.