Deposition of ultrafine particle in a duct flow by twisted-tape insert

In this pilot study, twisted tape (TT) was first used for deposition enhancement for ultrafine particles (UFPs). The particle removal enhancement of TT was measured experimentally. Polydisperse sodium chloride (NaCl) particles were used as ultrafine particles (UFPs). The upstream and downstream size-resolved particle concentrations of the NaCl particles were measured, and the results were used to compute the particle deposition velocity ratio achieved by TT for 5 different size groups. The duct with a TT insert recorded a higher particle deposition velocity ratio than that without the insert, peaking at 3.3 times for particles size group between 50 nm–100 nm. The experimental results reveal that the friction factors of the ducts with TT inserts were higher than those of the empty duct. Parameter such as the performance ratio was also calculated. Discussion on the deposition performance was also addressed.