Single Fibre Collection Efficiency : Infångningseffektiviteten för ett fiber

Abstract: A personal computer program, FiFi, that makes a real-time two-dimensional simulation of the dynamic deposition process of particles on one or two fibres, has been developed. The code has been used to numerically calculate the collection efficiencies of spherical particles on a clean single fibre. The calculations are based on a 10 term expansion of a solution of Oseen's approximation of Navier-Stokes equations. An extended operational efficiency definition has been developed. The results are compared with calculations based on flow filters. The implications on the calculated results of commonly used approximations, such as zero gravity and particle size expressed as aerodynamic equivalent diameter, were quantified for spherical particles. The influences on the collection efficiency of 1-100% variations of particle density, air temperature, air viscosity, air density, air mean free path, relative humidity and air velocity were calculated. A formula to calculate the collection efficiency as a function of the particle diameter and the fibr diameter has been derived from the numerical results. The validity range of the new formula was tested. A pilot experiment with the objective to verify the theoretical results has been made. The experimental results show good agreement with the theoretical results.