Study On The Deposition Characteristics Of Indoor Particles On Textile Surfaces

The problem of indoor particle pollution is attracting more and more attention of the government and public.As one of the important fate of particles,deposition has an important impact on the concentration and size distribution of indoor particles.In modern indoor environment,decorative fabrics are used more and more widely,and the proportion of fabric surfaces in the whole indoor environment is also increasing.However,there are few literatures related to fabric surfaces in the current study of indoor particle deposition.Therefore,it is of great significance to study the deposition characteristics of particles on the indoor fabric surfaces for improving the prediction model of indoor particle deposition,developing functional decorative fabrics and efficient cleaning methods for fabric surfaces.In this paper,the methods of experiments,model prediction and CFD simulation were used to study with emphasis the deposition characteristics of particles on the indoor vertical textile surfaces.The main contents of this paper are as follows:First,a small-scale chamber was built specially to study the deposition characteristics of particles on the fabric surfaces.The appropriate particle type,particle size,the device of particle generation and measurement were selected.After screening the characteristic parameters of fabric structure and surface that may affect the particle deposition,the surface roughness and porosity of the fabric were taken as the research object.Second,the effect of roughness of the vertical textile surfacs on the particle deposition was studied.Eight textile samples with different surface roughness were selected,and their surface roughness were measured by two surface analysis techniques.Through the deposition experiments conducted in the small-scale chamber,it was found that the trend of the deposition loss rate coefficient with the surface roughness is related to the fabric tightness,and the degree of influence on the particle deposition of vertical textile surface roughness is related to the near-surface airflow velocity and particle size.Third,the fabric porosities of two groups of samples were obtained by theoretical formula and computer image processing technology,and the effect of fabric porosity on particle deposition was studied experimentally.The results show that both the inter-yarn porosity and inter-fiber porosity of textile material could affect the particle deposition,however,the trend of the deposition loss rate coefficient with increasing inter-yarn porosity differs from that with increasing inter-fiber porosity.Fourth,the analytical model proposed by Lai and Nazaroff to predict the deposition velocity of particles on smooth surfaces was modified,and the deposition velocity of particles on the surfaces of the textile samples were predicted by the modified model.After comparing the predicted values of the above modified model with the corresponding experimental data,it was found that they are in good agreement,but the difference between the predicted values and the experimental data increases with the increase of air speed and surface roughness.Finally,the influence of structure and surface characteristics of yarns in the textile material,as well as the density of particles on the particle deposition were studied by means of CFD numerical simulation.By modifying the geometric parameters and surface roughness of yarns in the fabric model,the amounts of particles in 8 sizes deposited on 16 fabrics were calculated by DPM model.The results show that the fabric porosity,the cross-section shape and surface roughness of yarns,as well as the particle density can all affect the deposition characteristics of particles on the vertical textile surfaces.