Evaluation of an optical particle sensor to determine the effect of nozzle shape on counting efficiency

The optical particle sensor (OPS), using light scattering from particles, is widely used in clean-rooms and in atmospheric environmental monitoring. However, parameters that affect the particle counting of the OPS have been less explored previously. The present study examines the effect of the nozzle shape on particle counting performance of the OPS. Experiments and simulation studies were carried out for four different nozzle shapes in conjunction with three different particle sizes. The effect of nozzle shape is evaluated not only by experiments analyzing the intensity of scattered light and particle velocity but also by simulation. Fluent was used to simulate the flow field and particle trajectories. We observed that particle velocity and trajectory are strongly dependent on the input nozzle shape, which in turn has an effect on the particle counting performance. Using these results, the design of OPS can be optimized to provide higher counting efficiency.