Determination of ultraviolet sensor location for sensor set-point monitoring using computational fluid dynamics Available to Purchase

A study was performed to investigate the use of computational fluid dynamics (CFD) coupled with a fluence rate model to determine ultraviolet (UV) sensor placement for a "set point" monitoring approach to UV reactor operation. Simulations were performed in a two-lamp closed conduit reactor using two fluence rate models: RADial line source integration (RAD-LSI) and multiple segment source summation (MSSS). In addition, simulations were performed assuming first order inactivation kinetics with two rate constants representing a high UV sensitive and a low UV sensitive microorganism. The optimal sensor location was determined by calculating the linearity of the reduction equivalent fluence (REF) as a function of the local fluence rate regardless of the UV transmissivity (UVT). Results showed that a small range of possible locations exist where the sensor can be placed to achieve a single REF for each fluence rate value. However, the predicted optimal location was a function of the selected fluence rate model and the target microorganism. The determination of the sensor location for sensor set point monitoring should be performed with the MSSS approach, which includes refraction, reflection, shadowing, and sensor characteristics. Moreover, simulations performed with the more resistant microorganism produced a narrower spatial range of optimal sensor locations than with the less resistant microorganism. Key words: model, CFD, UV disinfection, monitoring, fluence rate.