Effect of collector arrangement on the impaction efficiency of a multi-collector system

Air filtration systems have been an essential means to maintain a clean environment and avoid health risks. The need to develop effective air filtration systems has been evident because of the immense increase in air pollution that poses a dire risk to the ecosystem. Conventional air filters are made of fibers that act as particle collectors. These fibers have random orientation and placement, and the filter relies on closely knit fibers to collect particles. Most filtration models used to quantify the particle collection in such systems assume that each fiber captures particles independently, uninfluenced by the neighboring fibers, thereby neglecting the effect of the relative orientation and placement of neighboring fibers on the particle collection. This study investigates the effect that the arrangement of cylindrical collectors has on the particle impaction efficiency of a multi-collector system using a simple two-cylinder model which represents any arbitrary pair of collectors placed in close vicinity. A numerical model is provided to analyze such a system and a detailed discussion for a Stokes number range of 0.2 – 100 is provided. The findings suggest that for Stokes numbers less than 10, the particle impaction on the collectors is very sensitive to the collector arrangement. Moreover, it was observed that for these Stokes numbers and appropriate collector arrangements the filter performance can be enhanced significantly. For Stokes numbers between 10 and 100 slight enhancements are possible in the filter performance for appropriate arrangements whereas for Stokes numbers greater than 100 the enhancement in the filter performance was found to be negligible. Furthermore, for Stokes numbers greater than 100 the study concluded that if the collectors are separated by at least a distance equivalent to one collector diameter in the transverse direction, collector arrangement does not have any effect on the particle impaction. The results also suggest that an ordered arrangement of collectors could result in an increment in the filter performance compared to a random arrangement. Finally, this study concludes that the effects of collector arrangement should be included in models used to investigate multi-collector systems, such as fibrous air filters. As a part of this study, a novel method of filtration has been introduced and analyzed. This novel method would use liquid bridges to replace the fibers of the conventional fibrous air filtration systems, to trap particles. This hypothesis is supported by preliminary proof-of-concept experiments.M.S.Includes bibliographical reference