Modeling pressure drop and collection efficiency of fibrous filters during loading

摘要

Fibrous filters are widely used as disposable media for air cleaning in automotive, HVAC andrnother applications. Making general predictions for the increase in pressure drop andrncollection efficiency of such filters as a function of dust load has been an important butrngenerally elusive goal.rnWe present the structure of a comprehensive model for the clogging process based on a betterrnunderstanding of the local phenomena around a fiber combined with information about therndistribution of fiber packing densities in the filter. “Local” input parameters are (i) thernpacking density of the particle deposit on the fiber and (ii) collection efficiency of a singlernfiber as a function of accumulated mass, particle size and gas velocity, as well as (iii) flowrnresistance. (The Stokes number is no longer being a valid scaling parameter during loading.)rnWe then discuss detailed results for one of the above input parameters, namely the packingrndensity of particulate material in the filter. We compare the morphology of depositedrnstructures on single fibers by confocal laser scanning microscope with values obtainedrnnumerically for a single fiber deposition process. We then make predictions of overallrnpressure drop on the basis of the comprehensive model and compare these with experimentalrndata for commercial filter media.