Photochemical reactor emission models

Other emission models for photochemical reactors include the extense source with superficial emission (ESSE) model in which the light source is assumed to be a surface [119], and the equivalent extense source with diffuse superficial emission (ESDSE) model which has been developed to calculate the radiant power profile generated by several superficial light sources [120], Radiation field modelling for photochemical reactors has been extensively reviewed by Cassano et al. [121, 122],... 

The main difference between photochemical and thermal reaction is the presence of a radiation-activated step. The rate of reaction of this step is proportional to the local volumetric rate of energy absorption (LVREA). For any emission model, the LVREA is a function of the spatial variables, of the physical properties and geometrical characteristics of the lamp-reactor system, and some physicochemical properties of the reacting mixture. The most important design parameter that is pertinent in photochemical and photocatalytic reactions is the effective attenuation coefficient. 

Photochemical reactor design involves simultaneous solution of the mass, energy, and momentum balance equations (as in normal reactors) along with equations for the radiation field and energy source (which are specific to photochemical reactors). Two approaches are possible (1) the intensity of the incident light, irrespective of the source, is used as the inlet boundary condition incidence models)-, (2) the emission from the source itself is part of the mathematical description emission models). The first approach has been extensively used but suffers from the weakness that the incident light is a function of scale, and hence a priori design from laboratory scale data tends to be uncertain. The second approach is formally correct, and involves no such uncertainty. 

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