Microstructure characterization of wood fiber pit adsorbing ultrafine particles emitted by diesel engine and simulation of its influence factors
Wood fiber is a porous biomass material, which has a strong adsorption ability for the PM (particulate matter) emitted by diesel engines. Through the SEM experiments, the fact that the pits of micron wood fiber after heat-treated can adsorb lots of ultrafine particles (aerodynamic diameter is less than 1μm) is shown clearly. In simulation, the particle concentration equations and fibrous filtration theory are applied. The collection media around pits is assumed as a cylinder. The simulation results show that the pits have relatively lower collection efficiency for the particles within the diameter from 0.4 to 0.6 μm. Out of the range of 0.4 to 0.6 μm, the collection efficiency increases rapidly, which implies that the pits have higher collection efficiency to filter the particles with the diameter out of 0.4 to 0.6 μm. Among all the affecting factors on collection efficiency, the reduction of permeate flow rate and the addition of tracheid wall thickness improve the collection efficiency. However, exhaust temperature has negligible influence on the collection efficiency.