Ray Tracing for Fluence Rate Simulations in Ultraviolet Photoreactors

The performance of photochemical reactors is governed by the spatial distribution of radiant energy within the irradiated region of the reactor. Ray tracing has been widely used for simulation of lighting systems. The central hypothesis of this work was that ray tracing can provide accurate simulations of fluence rate fields within ultraviolet (UV) photoreactors by accounting for the physical and optical phenomena that will govern fluence rate fields in UV photoreactors. Ray tracing works by simulating the behavior of a large population of rays emanating from a radiation source to describe the spatial distribution of radiant energy (i.e., fluence rate) within a system. In this study, fluence rate calculations were performed using commercial ray tracing software for three basic UV reactors, each with a single low-pressure Hg lamp. Fluence rate calculations in the ray tracing program were based on the formal definition of fluence rate, calculated as the incident radiant power from all directions on a small spherical receptor, divided by the cross-sectional area of that sphere. The results of this study demonstrate that ray tracing can provide predictions of fluence rate in UV radiative systems that are close to experimental measurements and the predictions of other numerical methods.