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Henning Ruden – One of the best experts on this subject based on the ideXlab platform.

  • capability of Air Filters to retain Airborne bacteria and molds in heating ventilating and Air conditioning hvac systems
    International Journal of Hygiene and Environmental Health, 2001
    Co-Authors: Martin Dr Ing Moritz, Hans Dr Ing Peters, Bettina Nipko, Henning Ruden


    Abstract The capability of Air Filters (filterclass: F6, F7) to retain Airborne outdoor microorganisms was examined in field experiments in two heating, ventilating and Air conditioning (HVAC) systems. At the beginning of the 15-month investigation period, the first filter stages of both HVAC systems were equipped with new unused Air Filters. The number of Airborne bacteria and molds before and behind the Filters were determined simultaneously in 14 days-intervals using 6-stage Andersen cascade impactors. Under relatively dry ( 12 °C) outdoor Air conditions Air Filters led to a marked reduction of Airborne microorganism concentrations (bacteria by approximately 70 % and molds by > 80 %). However, during long periods of high relative humidity (> 80 % R. H.) a proliferation of bacteria on Air Filters with subsequent release into the filtered Air occured. These microorganisms were mainly smaller than 1.1 μm therefore being part of the respirable fraction. The results showed furthermore that one possibility to avoid microbial proliferation is to limit the relative humidity in the area of the Air Filters to 80 % R. H. (mean of 3 days), e. g. by using preheaters in front of Air Filters in HVAC-systems.

  • Air Filters from hvac systems as possible source of volatile organic compounds voc laboratory and field assays
    Atmospheric Environment, 1999
    Co-Authors: Hans Schleibinger, Henning Ruden


    Abstract The emission of volatile organic compounds (VOC) from Air Filters of HVAC systems was to be evaluated. In a first study carbonyl compounds (14 aldehydes and two ketones) were measured by reacting them with 2,4-dinitrophenylhydrazine (DNPH). Analysis was done by HPLC and UV detection. In laboratory experiments pieces of used and unused HVAC Filters were incubated in test chambers. Filters to be investigated were taken from a filter bank of a large HVAC system in the centre of Berlin. First results show that – among those compounds – formaldehyde and acetone were found in higher concentrations in the test chambers filled with used Filters in comparison to those with unused Filters. Parallel field measurements were carried out at the prefilter and main filter banks of the two HVAC systems. Here measurements were carried out simultaneously before and after the Filters to investigate whether those aldehydes or ketones arise from the filter material on site. Formaldehyde and acetone significantly increased in concentration after the Filters of one HVAC system. In parallel experiments microorganisms were proved to be able to survive on Air Filters. Therefore, a possible source of formaldehyde and acetone might be microbes.

Qingyan Chen – One of the best experts on this subject based on the ideXlab platform.

  • investigation of the performance of Airliner cabin Air Filters throughout lifetime usage
    Aerosol and Air Quality Research, 2013
    Co-Authors: Junjie Liu, Qingyan Chen, Shengxiong Ren, Weiyou Yin


    The Air supply from an Airliner ventilation system is a mixture of outside Air and recirculated Air that passes through a high efficiency particulate Air (HEPA) filter. The effectiveness of two commercial-available Airliner cabin Air Filters were investigated in laboratory-based measurements due to the practical restrictions on Airliner cabin filter testing during usage. The filtration efficiency and pressure drop were assessed at a particle size range of 20–500 nm under various Airflow rates throughout the filter usage period. The Most Penetrating Particle Sizes (MPPS) were observed at ~150 and ~55 nm, where the filtration efficiency was 86% and 99% at the rated Airflow rates (1600 m 3 /h and 1970 m 3 /h), respectively. The filtration efficiency decreased in response to the increased Airflow rate from 1000 m 3 /h to 2200 m 3 /h, with the greatest reduction (~10%) occurring at MPPS. An increase of 250 Pa in the pressure drop across the filter was observed as the Airflow rate increased from 1000 m 3 /h to 2200 m 3 /h. Increased filter usage led to increases in both filtration efficiency and the pressure drop. The actual filter usage was estimated using dust loading in the laboratory. Filtration efficiency increased ~10% and the pressure drop increased ~800% when 220 g/m 2 dust was loaded on the filer, corresponding to ~6000 hours filter usage at an in-cabin PM10 concentration of 100 μg/m 3 . Explicit relationships among filtration efficiency, pressure drop and filter usage under various in-cabin particle concentrations are presented as a reference to facilitate the use of more appropriate Airliner cabin Air filter exchange periods.

Zhong Lin Wang – One of the best experts on this subject based on the ideXlab platform.

  • triboelectric nanogenerator enhanced multilayered antibacterial nanofiber Air Filters for efficient removal of ultrafine particulate matter
    Nano Research, 2018
    Co-Authors: Chang Bao Han, Zhong Lin Wang, Jing Jing Tian, Tao Jiang, Yu Bai, Jin Hui Nie


    We developed a high-efficiency rotating triboelectric nanogenerator (R-TENG)-enhanced multilayered antibacterial polyimide (PI) nanofiber Air Filters for removing ultrafine particulate matter (PM) from ambient atmosphere. Compared to single-layered PI nanofiber Filters, the multilayered nanofiber filter can completely remove all of the particles with diameters larger than 0.54 μm and shows enhanced removal efficiency for smaller PM particles. After connecting with aR-TENG, the removal efficiency of the filer for ultrafine particles is further enhanced. The highest removal efficiency for ultrafine particulate matter is 94.1% at the diameter of 53.3 nm and the average removal efficiency reached 89.9%. Despite an increase in the layer number, the thickness of each individual layer of the film decreased, and hence, the total pressure drop of the filter decreased instead of increasing. Moreover, the nanofiber film exhibited high antibacterial activity because of the addition of a small amount of silver nanoparticles. This technology with zero ozone release and low pressure drop is appropriate for cleaning Air, haze treatment, and bacterial control.