Effect of highly reflective material on the performance of water ultraviolet disinfection reactor

Abstract

The use of materials with high reflectivity on the surfaces of inner walls plays a significant role in enhancing the performance of ultraviolet (UV) reactors. In this study, the reactor efficiency is evaluated by changing the materials of the inner wall surfaces of the multi-lamp reactor from stainless steel to aluminum. The effect of water UV transmittance, flow rate, lamp power, and different modes of active lamps is studied on the effectiveness of inner wall reflection. Four turbulence models including standard k-ε, realizable k-ε, standard k-ω and SST k-ω, are used for the simulation of the flow field in a cross-flow UV reactor. The discrete ordinates model is applied to calculate the UV radiation field. The prediction of the velocity field showed that the SST k-ω model fits better with the experimental data. The results showed that if the inner wall is made of aluminum, the effect of reflection on the reactor performance increases with increasing UV transmittance and lamp power and decreasing flow rate. Investigations on lamp position showed that the effect of reflectivity becomes more apparent by reducing the lamp distance from the inner wall. Therefore, the reactor performance improvement is about 87–91% by putting the lamps closer to the wall and changing the wall material from stainless steel to aluminum.