| Pollution of the environment with the rapid development of science and technology,The economy of China increasingly aroused attention,at the same time,with the improvement of living standards,People are more demanded about the quality of indoor air quality.From the beginning of formaldehyde,to TVOC,to PM10,the last is the PM2.5 problem.At present,the most effective way to reduce PM2.5 concentration is the air filtration.The relevant equipment used in this technology is generally air purifier,and its core is the internal air filtration material,so the quality of air filtration material can affect the filtration performance of the device.Based on the investigation in shenyang of varying concentrations of PM2 5 characteristics as background in nearly two years.Aiming at this phenomenon,take the existing air filtration material as an example,the filtration properties of the samples were studied by means of the experiment device.Under different wind speeds,the concentration of PM2.5 purification and the influence of the pressure drop;Through establishing numerical simulation model of experiment equipment,imported under the influence of the wind speed simulation area,the velocity vector and the pressure change trend,putting forward the reasonable ventilation scheme and technical measures,provide theoretical basis for the study of the related air filter and practice reference,further for indoor fresh air system,this article main research conclusion is as follows:(1)The study area for almost 2 years PM2.5 levels showed a trend of gradual decline in volatility,its average concentration mainly according to the winter>spring>autumn>summer,that illustrate the impact of meteorological factors can play a season;The daily change trend of PM2.5 concentration indicates the effect of temperature on the diffusion and dilution of PM2.5.According to the concentration of different places in shenyang,the southern region is generally higher than the north,and the western region is generally higher than that of the east.The spatial distribution features are mainly affected by the surrounding living area.The concentration of PM2.5 in indoor and outdoor samples was determined,and the regression curves were of positive correlation.(2)In view of the existing air purification materials,of 9 kinds of membrane structures,the dynamic membrane filtration performance test bed,adopting PM2.5 detector test before and after the mass concentration of membrane material,wind pressure gauge pressure drop before and after the test of membrane materials.The results showed that:From the point of view of filtration efficiency,the filtration efficiency of gauze filter membrane and cotton cloth filter membrane is lower,about 20%-40%,and the filtration efficiency of non-woven membrane filter membrane is 30%-55%.And the filter efficiency of activated carbon fiber filter is 70%-78%,at a high level.The composite membrane material uses a non-woven fabric as a substrate.The combination of the two materials increases the filtration efficiency compared to single membrane materials.The best filtration efficiency of all materials is HEPA membrane,up to 95%,which is currently used.Full-featured latest comprehensive material.Judging from the filtering resistance:In the single membrane,the resistance of the type A membrane material is the lowest,the range is from 2 to 20 Pa,the resistance of the type B membrane material ranges from 10 to 80 Pa,and the resistance of the type C membrane material ranges from 60 to 80 Pa.Hepa filter material resistance is high,120-300pa.The filtration resistance of the composite membrane was increased compared with that of the single membrane,and it was maintained at about 160pa.(3)lt is difficult to meet people's needs because of the problems of low filtration efficiency or too large resistance of filter membrane materials.Using analytic hierarchy process(ahp)to comprehensive evaluation of nine kinds of membrane materials,respectively from the filtration efficiency and filtration resistance,porosity,gram weight and price various weighting comparison,finally according to the size of the numerical,choose good material of activated carbon fiber as the modified material,further modification,design more efficient low resistance of air purification materials.(4)On the activated carbon fiber loaded with photocatalyst TiO2,the ACF/TiO2 modified material was prepared by sol-gel method,and the influence of filter layer thickness,TiO2 investment and filtration speed on the filtration efficiency of PM2.5 was studied.The optimal conditions were found through orthogonal experiment,with wind speed of 1m/s,TiO2 at 15%and ACF thickness of 30mm,which could improve the filtration effect of the whole modified material on PM2.5,up to 95%.(5)By establishing a physical model of the air purifier and comparing the experimental value with the simulated value,the reliability of the simulation is verified.The porous media model was used to simulate the modified activated carbon fiber materials.Numerical simulations were performed for different inlet conditions.The results show that when the inlet air velocity is controlled from lm/s to 5m/s;the air flow tends to be steady and the cross section is 0.1.There is a large resistance at m,that is,the cross-sectional area of the air intake and air outlet should be increased as much as possible to obtain a better internal flow field condition.Different air purifier positions have a great influence on the airflow distribution of indoor PM2,5 concentration.When the purifier is located at position A under the infiltrating wind,the purifying effect is the worst,and the purifying effect is best when the purifier is at position C of the infiltration wind. |
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