Study On The Performance Of Artificial Dust For Air Filter Detection

As a device to control air cleanliness,air filter plays a key role in human daily life and industrial production.In order to meet the needs of people for different air cleanliness,air filters of different filter grades are needed,so the accurate evaluation of filter performance is very important.At present,the evaluation method for the performance of air filter is to simulate the pollution process of filter by artificial experiment,that is,to use fan to blow and scatter the artificial experimental dust with known particle size distribution on the filter in the confined space,and then calculate the proportion of particles with specified diameter to be intercepted,based on which,to evaluate the performance of air filter and classify the filter grade,to apply in different scenes.However,the existing experimental results of artificial simulation are far from the actual performance of the filter,which overestimates the filtration efficiency of many products.The difference between the performance of artificial experimental dust and that of atmospheric natural dust is a basic problem worthy of further study.In this study,a kind of scientific,reasonable and ideal artificial dust was developed for some problems of the existing artificial dust storm.At the same time,according to the parameters of dust holding capacity,its performance was verified in the laboratory.By means of comparative experiment,the dust capacity data of artificial dust and atmospheric dust under the same conditions are tested,and the main problems of artificial dust still exist are obtained.The possible cause of the problem particle size distribution is discussed.In view of the particle size distribution,two kinds of experimental dust with large difference in particle size were selected for comparative experiments to verify the influence of particle size distribution on the dust capacity.In order to further study the causes of different dust holding capacity and explore the movement rule of dust with different particle size in the filter material,the filter material of air filter after dust holding was analyzed by means of sem and tem x-ray scanning technology,including the state of particle aggregation,the difference of chemical composition and the distribution of elements.In this study,a new kind of artificial dust was developed,and its particle size distribution,homogeneity and stability were evaluated.The results show that the artificial dust samples meet the requirements in the above three aspects.The results of the comparison test between the artificial dust and the atmosphericdust show that the capacity of the artificial dust is 4.7g more than that of the atmospheric dust under the condition of the same final resistance.For the 45 g dust generation,the calculation of the filtering efficiency is caused by a deviation of about 10%,and the evaluation of the filter performance is greatly wrong.Considering that the gravity and inertia force are inversely proportional to the particle size,the diffusion distance is directly proportional to the particle size.The smaller particle size of atmospheric dust results in smaller gravity settlement,shorter inertia travel and longer diffusion radius,all of which lead to its better penetration into the air filter,so as to evenly distribute in the whole air filter and avoid the sharp increase of filter surface resistance.So in the case of the same final resistance,the capacity of artificial dust is more.Furthermore,the comparison experiment of two kinds of experimental dust with different particle size proves that the smaller the particle size is,the larger the dust capacity is.In order to further explore the causes of this phenomenon,we use the electron microscope to observe the filter material fiber of the air filter after dust holding,and find that the agglomeration phenomenon of the air dust on the filter material fiber body provides conditions for the rapid increase of resistance,while the artificial dust is evenly distributed on the fiber body,so the resistance will slowly increase.At the same time,through the analysis of the experimental dust deposited on the filter fiber by x-ray energy spectrum,it is concluded that the main component of the air dust and the artificial dust is sio2,but the content of sio2 in the artificial dust is about half of that in the air dust.It provides a reference for the next research and development of artificial dust,that is,the particle size of artificial dust should be further reduced and the content of sio2 should be doubled.Raw materials with higher silicon content can be used to make artificial dust.