How to build a satisfactory indoor environment has become increasingly important. In this paper, the synthesis and improvement of the most widely used polyester materials in China were carried out based on two different preparation methods, and the structures and filtration performances were tested and analyzed. The results showed that a carbon black coating was wrapped on the surfaces of the new synthetic polyester filter fibers. Compared with the original materials, the filtration efficiencies of PM10, PM2.5, and PM1 were increased by 0.88–6.26, 1.68–8.78, and 0.42–4.84%, respectively. The best filtration velocity was 1.1 m/s, and the new synthetic polyester materials with direct impregnation demonstrated superior filtration performance. The filtration efficiency of the new synthetic polyester materials was improved on the particulates with sizes of 1.0–5.0 μm. The filtration performance of G4 was better than that of G3. The filtration efficiencies of PM10, PM2.5, and PM1 were improved by 4.89, 4.20, and 11.69%, respectively. The quality factor value can be used to assess the comprehensive filtration performance of air filters in practical applications. It could provide reference values for the selection of synthetic methods of new filter materials.

No abstract

With the increasing popularity of fresh-air filtration systems, the methods of determining the outdoor PM2.5 design concentration have become more important. However, the monitoring of atmospheric fine particles in China started relatively late, and there are relatively few cities with complete data, with obvious regional differences, which led to many problems in the selection of air filters for fresh-air filtration systems. In this paper, three methods of determining outdoor PM2.5 design concentration were analyzed using the daily average concentration of PM2.5 in 31 provincial capital cities from 2016 to 2020. Six typical cities in different regions were also taken as examples. The advantages and disadvantages of the three existing statistical methods were compared and analyzed, as well as the corresponding differences in the selection of outdoor PM2.5 concentration value on the filter systems. The results showed that the method of mathematical induction was more accurate and reasonable for the calculation of outdoor PM2.5 design concentrations. The local outdoor PM2.5 design concentration could be quickly calculated using the recommended coefficient K and annual average PM2.5 concentration of the region, especially for small and medium-sized cities without monitoring data. However, the recommended coefficient K should be provided based on the specific region, and should be divided into values for strict conditions and normal conditions during use. This would provide a simple and effective way to select the correct air filters for practical engineering.

With the widespread popularity of fresh air filtration systems, the pipes materials have become one of the important parameters that affect the overall performances of the fresh air systems. In this paper, an experimental study on the deposition of particulate matters on two commonly used pipes materials (PVC and PE) in the market was tested, and conducted an in-depth analysis of its influencing factors. The results showed that the deposition rates of particulate matters in the PVC pipe increased with the increased of the inlet velocity, and the deposition rate reached the maximum at the velocity was 4.0m/s. While the deposition rates of particulate matters in the PE pipe were increased first and then decreased with the increased of the inlet velocity, and the deposition rates reached the maximum at the velocity was 3.5m/s. The PM values deposition rates showed the pipe systems of PE were higher than that of PVC. With the increased of the particle sizes, the tends of deposition rates increased gradually. There were big differences in the deposition rates of particle sizes of less than 1.0?m, and the largest difference was 0.615?m, with 8.44%. Therefore, reasonable pipeline materials should be selected comprehensively according to actual need in the process of pipeline installation and use. It would provide a useful reference value for the selection of pipeline materials in the fresh air filtration systems in the post-epidemic era.