Pleated filter media are widely used in particulate filtration, but the particle deposition and pressure drop during particle loading remain insufficiently explored. This study visualizes the particle deposition patterns in pleated filter media, along with the evolution of pressure drop and the effective filtration area (EFA) using simulations. The results indicate that, as the volume of deposited particles increases, the pressure drop of the pleated filter media initially grows linearly, but this rate of increase accelerates as particle deposition continues. The particle deposition characteristics are related to the pleat ratio. A smaller pleat ratio results in a smaller initial EFA, leading to a high initial resistance growth rate. Conversely, a larger pleat ratio leads to faster aggregation of particles, resulting in a faster rise in the resistance growth rate. The dust-holding capacity is optimal at a pleat ratio of 6.67. When the inlet flow rate or the particle size increases, it is more favorable to reduce the pleat ratio. The reliability of the results is verified using experiments, and the error is within 20%. The findings provide theoretical and practical insights for optimizing the design of pleated filter media for better performance in particulate filtration.

Protection from nuclear biochemical aerosol and air pollution pays attention to aerosol mass concentration. The concentration of upstream aerosol of the commonly used filtration efficiency detection device for high-efficiency filter materials is low, making it insufficient for detecting the filtration efficiency of high-efficiency filter materials. This study designed and built a set of filtration efficiency detection devices for high-efficiency filter materials based on mass concentration. By adjusting the oil bath temperature, injection pressure, the degree of spiral-separator separation, as well as the number and size of nozzles, we investigated the effects of each condition on the concentration and particle size distribution of aerosol generation. As a result, the oil mist generator of the device can stably generate high-concentration aerosol with a mass concentration of up to 1587.9 mg/m³ and a number concentration of up to 10⁷–10⁸ P/cm³. The high-concentration aerosol generated can meet the E11–U15 filter material performance requirements.

Antibacterial filter materials have been effectively utilized for controlling biological contaminants and purifying indoor air, with the market for such materials experiencing continuous expansion. Currently, textile antibacterial testing standards are widely adopted to evaluate the antimicrobial efficacy of filter materials, yet no dedicated assessment protocols specifically tailored for filtration media have been established. This study aims to investigate the applicability of textile antibacterial testing methods to high-efficiency glass fiber filter materials (filtration efficiency > 99.9%), as well as to explore the factors that affect the rate of bacterial elution from high-efficiency glass fiber filter materials. By referencing the textile antibacterial testing standard (absorption method), significant discrepancies in bacterial recovery counts were observed between the high-efficiency glass fiber materials and the various textile control samples, with the former exhibiting a markedly lower recovery rate (approximately 10%). Pore structure and wettability analyses revealed the underlying causes of these differences. To ensure the accuracy of the antibacterial evaluation results, the effects of oscillation elution parameters (time and intensity) and material incubation conditions (duration, sealing and humidity) on bacterial recovery rates in glass fiber filter materials were systematically investigated to optimize the elution methodology. The results indicate that specimen type, size, elution method, incubation duration (4 h or 24 h), sealing conditions, and environmental humidity (10% or 30%, 60% and 95% RH) collectively influence bacterial recovery efficiency. The highest recovery efficiency (55%) was achieved when the filter materials were incubated in a sealed environment with humidity maintained at ≥60% RH. These findings emphasize the critical need to establish clear and specialized antibacterial performance testing standards for filter materials. The study provides essential guidance for developing material-specific evaluation protocols to ensure a reliable and standardized assessment of antimicrobial efficacy in high-efficiency filtration systems.

To satisfy the requirements of channel-type ultra-low penetration air (ULPA) filters for high filtration efficiency, low pressure drop, and good corrugation processability, a three-layer composite filter medium with a bast-fiber surface layer/glass wool–lyocell blended core layer/bast-fiber surface layer structure was designed and prepared. The effects of surface-layer material, core-layer fiber composition, surface-layer basis weight, and processing conditions on the overall performance of the medium were systematically investigated. Bast-fiber paper exhibited the best corrugation processability and mechanical performance and was selected as the surface layer. The optimal core-layer composition was 25 wt.% 475-79 glass wool fibers, 30 wt.% 475-59 glass wool fibers, and 45 wt.% lyocell fibers, yielding an original-sheet filtration efficiency of 99.9996% and a pressure drop of 381 Pa. Further optimization showed that a bast-fiber surface layer with a basis weight of 15 g/m² provided the best balance among pleat retention, structural stability, and low-resistance characteristics. Under optimized corrugation conditions of 120 °C roller temperature, 10 m/min roller speed, and 0.480 mm roller gap, a desirable pleat morphology suitable for channel-type structures was obtained. The resulting channel-type ULPA filter maintained a filtration efficiency of 99.99954%, while increasing the effective filtration area by 51.6% and reducing the pressure drop by 26.1% compared with a conventional pleated filter with the same dimensions. These results provide a useful reference for the design and application of low-resistance, high-efficiency filter media for channel-type ULPA filters.

Air pollution has drawn increasing attention. The channel-type structure, as an ideal energy-saving and resistance-reducing strategy for air filters, can effectively lower filtration resistance. However, current commercial channel-type filters generally exhibit only medium or low filtration efficiency, and the use of plant fibers as raw material limits their application in high-efficiency filters. In this study, high-efficiency glass fiber filter paper was combined with a channel-type structure, and the formulation and processing techniques suitable for the channel-type design were systematically investigated, leading to the fabrication of channel-type high-efficiency filters. The optimal formulation was determined to be a blend of glass wool fibers and 6 mm Tencel fibers in a 6:4 ratio, coated with a thermosetting resin, which yielded filter paper suitable for wave-pleating. The resulting filter paper demonstrated a filtration efficiency of 99.9624%, a pressure drop of 265.6 Pa, and a pleat aspect ratio of 0.209. Using this formulation, pilot-scale filter paper was produced and wave-pleated under processing conditions including a roller speed of 5 m/min, a roller gap of 0.4 mm, and a roller temperature of 160 °C, which was then used to fabricate channel-type high-efficiency filters. The finished channel-type filters achieved a filtration efficiency of 99.9940% with a pressure drop of 164.0 Pa. Compared to traditional pleated filters of the same volume and efficiency rating, the channel-type filter exhibited a 49.53% larger filtration area, a 33.13% lower face velocity, and a 31.67% reduction in pressure drop. This work offers a novel approach to reducing resistance and enhancing efficiency in air filtration systems.