Influence of secondary flows on the collection efficiency of a cylindrical electrostatic precipitator

• The influence of secondary flows on the collection efficiency was evaluated.
• Collection suffers an adverse effect with hydrodynamic Reynolds numbers below 200.
• Efficiencies do not depend on recirculation with higher Reynolds numbers.

Submicron bioaerosols collection with an axisymmetric wire/cylinder electrostatic collector was modelled in the laminar regime. The model was based on a particle population balance. In addition to the five dimensionless numbers identified in a previous paper, an extra dimensionless number which is the ratio of the electric charge scale acquired by convection to the total charge scale acquired by the particle was also revealed.The influence of recirculation characterising various flow regimes as shown in the aforementioned paper was evaluated. These severely disturb the spatial distribution of the particles. However, a comparison of the collection efficiency in these regimes showed that collection efficiencies do not depend on recirculation with high hydrodynamic Reynolds numbers and suffer an adverse effect below about 200. A critical analysis of a simplified criterion based on the Deutsch number for sizing wire/cylinder electrostatic precipitators was also performed.