Developing an optical module for large-scale UV-LED water disinfection reactors by numerical modeling

Abstract

The emergence of alternative UV radiation sources, such as ultraviolet light emitting diodes (UV-LEDs), has created an opportunity to develop novel water disinfection reactors. Radiation management is a major parameter affecting the performance of these reactors, and it is essential to develop highly efficient optical modules to pave the way toward commercially viable systems. An effective way to improve optical efficiency is by creating collimated beams. Here, an optical module design for the collimation of UV-LED radiation is proposed that employs multi-parabolic aluminum reflectors. To design and optimize the optical module, a ray optics computational model was initially developed to study the radiation profiles of multi-UV-LEDs and optical manipulators with complex geometries. This model was applied to the virtual prototyping and optimization of the reflector’s geometry. Once the optimized design was determined, a physical prototype was fabricated and characterized.The developed module was characterized using several scenarios that confirmed the formation of collimated beams. The simulation results were further evaluated against experimental measurements, quantitatively and qualitatively, indicating good agreement. It was found that the reflectors significantly increased the uniformity of the fluence rate and its magnitude at longer distances from the radiation source (e.g., 30 times higher at 22 cm). The optical module was then installed on a water disinfection reactor, and the radiation profile was measured in the reactor filled with water. The optimally designed reflectors resulted in significantly better distribution and preservation of the irradiance along a water disinfection reactor, ultimately increasing the fluence rate and the delivered UV dose.