| 1. |
- Afshari, Alireza, 1956, et al.
(författare)
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Naborøg og overførsel af partielforurening
- 2010
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Ingår i: HVAC - Magasin for klima- og energiteknik, miljø, bygningsinstalltioner & -Netværk. ; 1:2010, s. 24-30
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Afshari, Alireza, 1956, et al.
(författare)
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Quantification of ultrafine particles from second-hand tobacco smoke infiltration
- 2010
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Ingår i: Proceedings of the CLIMA 2010 Conference: 10th REHVA World Congress 'Sustainable Energy use in Buildings', 8 pages.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents some of the results of a second-hand tobacco smoke intervention studycarried out in 19 flats in four different buildings. Two of the investigated buildings were nonrenovatedand two others were renovated. The aim of the study was to quantify infiltration ofultrafine particles from a smoker's flat into a non-smoker's flat. In addition, several tests werecarried out to describe some solutions for reduction of particle concentrations in the smoker'sflat and the non-smoker's flat. The air change rates and the indoor particle concentrationswere measured continuously during the measuring periods. The particle sources (particlegenerating activities) were cigarette-burning in the un-occupied buildings and candle-burningin the occupied buildings. Reductions of the concentration of ultrafine particles using aircleaning devices were studied. Results showed that the transfer of ultrafine particles wasabout 9% when the source flat was located below the receiving flat, whereas the transfer was1-2% when the source flat was on the same floor as, or above, the receiving flat.
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| 3. |
- Deng, Qihong, et al.
(författare)
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Source Apportionment and Chemical composition of particulate matter (PM10) in university classrooms
- 2009
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Ingår i: Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology). - 1672-7207. ; 40:2, s. 332-328
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Tidskriftsartikel (refereegranskat)abstract
- The inhalable particulate matter (PM10) was continuously monitored and sampled in the classrooms of Central South University at Changsha by Tapered Element Oscillating Microbalance 1400a (TEOM 1400a) from September to December, 2007. The chemical compositions of the PM10 samples were analyzed by the X-ray fluorescence (XRF), and then the source apportionment of the classroom particles was investigated by the principal component analysis (PCA). The results show that the mean PM10 concentration in classrooms is (176.56±57.63)
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| 4. |
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| 5. |
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| 6. |
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| 7. |
- Ekberg, Lars, 1962, et al.
(författare)
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Removal of ultrafine particles by ventilation air filters
- 2009
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Ingår i: 9th International Healthy Buildings Conference and Exhibition, HB 2009; Syracuse, NY; United States; 13 September 2009 through 17 September 2009.
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Konferensbidrag (refereegranskat)abstract
- The purpose of the investigation is to clarify how the filtration efficiency for ultrafine particles (UFPs) varies depending on the aerosol size distribution upstream of the filter. Filter classes F5-F7 (according to the European standard EN779) and combinations of these filter classes are studied.The fractional filtration efficiency for particles ranging from 5 nm to 100 nm was estimated based on previous publications. The downstream concentration and size distribution was calculated for each of four outdoor aerosols representing both urban and rural conditions. When interpreting data expressed as the total number concentration (dp>5 nm), the studied F7-filter (corresponding roughly to MERV 13 according to the applicable US-standard) showed filtration efficiencies between 65% and 83%. The results also indicate that measurements with an instrument providing the number concentration of particles larger than 20 nm will underestimate the total UFP-filtration efficiency by about 10%-units, estimated as an average value for all of the studied filter classes.
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| 8. |
- Kadribegovic, Ragib, 1975, et al.
(författare)
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Air Cleaning by Photo Catalytic Oxidation: An Experimental Performance Test
- 2011
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Ingår i: ASHRAE Transactions. - 0001-2505. ; 117:1, s. 426-433
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents the results from an experimental evaluation of a novel air cleaner based on UVC radiation at 253.7 nm in combination with a titanium dioxide (TiO(2)) catalytic converter. The wavelength of the UV light is selected with the purpose of enhancing the capability of the device to deactivate micro-organisms. Furthermore, the selected UV-wavelength is expected not to cause any substantial generation of ozone. The air cleaner, denoted PCOC3, consists of three photo catalytic oxidation (PCO) chambers connected in series. The device is equipped with a pre-filter for removal of airborne particles (MERV 11). The air cleaner is intended for in-duct use, i.e. integration in central ventilation systems. In a subset of the experiments ozone was generated by an electrical spark generator placed upstream of the tested air cleaner and measured downstream by a direct reading instrument based on UV-spectroscopy. In another subset of experiments selected VOCs were injected into the test-rig and the decay was measured after the VOC injection had been stopped. The measurements showed no signs of any ozone being generated by the PCOC3. Instead the results indicate that ozone is captured by the device at a removal rate corresponding to 67 air changes per hour in the test-rig used, which, in turn corresponds to a single pass efficiency of about 15%. Also the studied VOCs were found to be removed by the PCOC3, but at substantially lower rates; in the range of a few air changes per hour only.
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| 9. |
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| 10. |
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| 11. |
- Shi, Bingbing, 1983, et al.
(författare)
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Influence of Filter Fiber Material on Removal of Ultrafine and Submicron Particles Using Carbon Fiber Ionizer-Assisted Intermediate Air Filters
- 2012
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Ingår i: ASHRAE Transactions. - 0001-2505. ; 118:PART 1, s. 602-611
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Konferensbidrag (refereegranskat)abstract
- Ultrafine and submicron particles are possibly highly related with respiratory and cardiopulmonary diseases and syndromes. Many studies show that an ionizer operated upstream of a ventilation air filter could enhance the particle collection efficiency of the filter, without affecting the pressure drop. However, most of these studies are based on one single fiber material and does not develop any comparison among different ventilation filters. This study investigates the influence of the fiber material and filter class on the enhanced efficiency. The influence of ion concentration is also considered. The experiments were conducted in a full-scale filter test rig and a chamber with 100% air re-circulation. Seven ventilation filters of class F5-F9 (MERV11-15), made of three types of fiber materials were tested in the filter test rig. A Scanning Mobility Particle Sizer (SMPS) was utilized to count ultrafine and submicron particles in the upstream and downstream air flow. In the chamber test, a charged synthetic filter of class G4 (MERV 8) was mounted in the air re-circulation system. A P-TRAK Ultrafine Particle Counter, a CI-500 optical particle counter and a Dust-TRAK Aerosol Monitor were used to measure ultrafine and submicron particles. The results show, under the given experimental conditions, that ionization could substantially improve the filtration efficiency. For example, assisted by the ionizer, the coarse G4 (MERV 8) filter showed a filtration efficiency that increased by about 30 to 40 %-units for submicron particles. For the same ion concentration, the enhanced efficiency of charged synthetic filters is higher than that of glass fiber filters, especially in the ultrafine particle size fraction. Similarly, with the same ion concentration, the charged synthetic filters of higher class showed higher enhanced efficiencies than the charged synthetic filters of lower class. Measurements showed a negligible generation of ozone, both in the filter test rig and in the test chamber experiments.
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| 12. |
- Shi, Bingbing, 1983, et al.
(författare)
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Intermediate air filters for general ventilation applications: An experimental evaluation of various filtration efficiency expressions
- 2013
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Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 0278-6826 .- 1521-7388. ; 47:5, s. 488-498
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Tidskriftsartikel (refereegranskat)abstract
- Neither the European standard nor the US standard for classification of intermediate class filters comprises testing of filter performance with respect to ultrafine particles (UFPs) or particles of the most penetrating size (MPPS). This could turn out to be a major lack in classification standards since UFPs have been pointed out as a serious health hazard. In this study, fractional efficiencies of eight new full-scale bag filters and twenty-three new filter medium samples were determined. The influence of air velocity and aerosol type was investigated, and correlations between efficiencies for UFPs (EFUFPs), MPPS-sized particles (EFMPPS) and 0.4 μm-sized particles (EF0.4μm) were established. The tested bag filters were challenged by four aerosol types: a neutralized atomized oil aerosol, the same oil aerosol but non-neutralized, a non-neutralized thermally generated oil smoke, and a “natural” indoor aerosol. The tests were carried out at different air velocities through the filter medium, ranging between 0.08 m/s and 0.22 m/s. The relationships that were observed between EFUFPs, EFMPPS, and EF0.4μm appeared to be linear within the observed filtration efficiency ranges. These relationships were similar regardless of the test aerosol type used, but somewhat different for glass fiber filters than for charged synthetic filters. Generally, EFMPPS was 10–20% lower than EF0.4μm. The influence of air velocity variations on the size resolved efficiency was determined. The glass fiber filters showed practically the same fractional efficiencies regardless of whether the test aerosol was neutralized or not. However, the charged synthetic filters showed substantially lower efficiencies when tested with the non-neutralized aerosol compared to the case when the aerosol was neutralized.
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| 13. |
- Shi, Bingbing, 1983, et al.
(författare)
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Ionizer Assisted Air Filtration for Collection of Submicron and Ultrafine Particles—Evaluation of Long-Term Performance and Influencing Factors
- 2015
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 49:11, s. 6891-6898
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Tidskriftsartikel (refereegranskat)abstract
- Previous research has demonstrated that unipolar ionization can enhance the filter performance to collect airborne particles, aeroallergens, and airborne microorganisms, without affecting the filter pressure drop. However, there is a lack of research on the long-term system performance as well as the influence of environmental and operational parameters. In this paper, both field and laboratory tests were carried out to evaluate the long-term particle collection efficiency of a synthetic filter of class M6 with and without ionization. The effect of air velocity, temperature, relative humidity, and particle concentration were further investigated in laboratory tests. Results showed that ionization enhanced the filtration efficiency by 40%-units during most of the operation time. When the ionization system was managed by periodically switching the ionizer polarity, the filtration efficiency against PM0.3–0.5 was maintained above 50% during half a year. Furthermore, the pressure drop of the ionizer-assisted M6 filter was 25−30% lower than that of a filter of class F7. The evaluation of various influencing factors demonstrated that (1) air moisture reduced the increase of filtration efficiency; (2) higher upstream particle concentration and air velocity decreased the filtration efficiency; and (3) the air temperature had very limited effect on the filtration efficiency.
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| 14. |
- Shi, Bingbing, 1983, et al.
(författare)
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Removal of ultrafine particles and particles of the most penetrating size by new intermediate class filters
- 2011
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Ingår i: Proceedings of the Indoor Air 2011 Conference, Austin, TX, USA, 6 pages.
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Konferensbidrag (refereegranskat)abstract
- Twenty-three new filter samples, including three different medium types, were tested in a small scale test-rig using a Scanning Mobility Particle Sizer (SMPS). The filtration efficiencies for ultrafine particles (UFPs) and particles of the most penetrating particle size (MPPS) were determined. The filters were of class F5-F9 according to the European filter standard, which roughly corresponds to MERV9-MERV15 according to the US-standard. The filters were challenged by the indoor aerosol prevailing in the laboratory. Additional tests were made using an oil aerosol. With the indoor aerosol, charged synthetic filters showed substantially higher MPPS efficiencies than glass fiber and uncharged synthetic filters of the same class did. With the oil aerosol, the different filter media types, belonging to the same filter class, showed similar efficiencies. The oil aerosol drastically reduced, or eliminated, the electrostatic filtration mechanism. For example F7 and F8 filters not influenced by electrostatic mechanisms typically showed 40% and 50% removal of MPPS particles respectively.
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| 15. |
- Shi, Bingbing, 1983
(författare)
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Removal of ultrafine particles by intermediate air filters in ventilation systems. Evaluation of performance and analysis of applications.
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Epidemiological and toxicological studies demonstrate that ultrafine particles (UFPs) are strongly related with respiratory and cardiovascular diseases and syndromes. One common method to reduce human exposure to particulate air pollution is the use of intermediate class filters (F5-F9 class filters according to EN779:2002). However, the efficiency of such filters, with respect to UFPs, is not well explored. Furthermore, neither the European standard nor the US standard for classification of intermediate class filters comprises performance with respect to UFPs or particles of the most penetrating size (MPPS). This could turn out to be a major lack in classification standards since UFPs have been pointed out as a potential serious health hazard. To fill in the gap, the purpose of the thesis is to evaluate the performance of intermediate class filters available on the Swedish market, and to correlate the efficiency for UFPs (EFUFP) and MPPS-size particles (EFMPPS) with the EN779 classification efficiency for particles of the size 0.4μm (EF0.4μm). The thesis also contains analyses of 1) air filtration for indoor particles of outdoor and indoor origin; 2) how to efficiently apply intermediate air filters in two-step air filtration systems and 3) ionizer assisted air filtration.Size-resolved filtration efficiencies of 23 filter sheets and 8 full-scale filters were tested in laboratory experiments with four types of upstream aerosols. The relationships between EFUFPs, EFMPPS and EF0.4μm were investigated under different testing conditions. The results showed that the electrostatic force from charged filter fibers has big influence on the shape of the efficiency curves. Additionally, the electrical charge state of the upstream aerosol is critical for the testing of charged synthetic filters. Linear relationships were found between EFUFPs, EFMPPS and EF0.4μm within the observed efficiency range for both glass fiber and charged synthetic filters. In general, EFMPPS was 10-20%-units lower than EF0.4μm. The values of EFUFPs were close to EF0.4μm for glass fiber filters, while EFUFPs were lower than EF0.4μm for charged synthetic filters. Theoretical analysis showed that filter operating hours and classes are critical to the cost of two-step filtration, i.e. a solution where a pre-filter protects the main filter. Under suitable operation, two-step filtration is not necessarily more expensive than single-step filtration. Another analysis investigated suitable filter class, filtration locations, and the ratio of supply to outdoor air flow rate, for efficient removal of particles coming from indoor and outdoor sources. The results can be used to recommend suitable air filters and ventilation rates/modes or to predict the existing system performances. Yet a separate study, based on measurements, shows that an F7 class filter assisted with an ionizer may reach an efficiency similar to that of a single F9 class filter.
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| 16. |
- Shi, Bingbing, 1983, et al.
(författare)
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The effectiveness of portable air cleaners against tobacco smoke in multizone residential environments
- 2010
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Ingår i: Proceedings of the CLIMA 2010 Conference: 10th REHVA World Congress 'Sustainable Energy use in Buildings', 8 pages.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this study was to investigate how the effectiveness of portable air cleaners(ACs) against tobacco smoke is influenced by the clean air delivery rate (CADR), the locationof the AC in relation to the pollution source and the apartment structure. The study was basedon field experiments and simulations with the CONTAM software. The AC effectiveness wasabout 80% for one AC, and 93% for two ACs in the studied apartment (volume=110m3).Ultrafine particles (UFP) exposure in a room without tobacco smoking (clean room) could bemuch less than in the source room if these rooms were not directly connected with each other(but indirectly connected via doors open to other rooms). Operating the AC in one of therooms without cigarette smoking could develop a partly isolated clean environment.However, this led to a rather low cleaning effectiveness for the concentration of ultrafineparticles in the apartment as a whole. If operating the AC in the room where cigarettes arebeing smoked, the UFP exposure in the whole apartment can be further reduced.
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| 17. |
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| 18. |
- Shi, Bingbing, 1983, et al.
(författare)
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Ultrafine particles control strategy in printer rooms: model and experiment study on portable air cleaner and HVAC combination
- 2009
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Ingår i: 9th International Healthy Buildings Conference and Exhibition, HB 2009; Syracuse, NY; United States; 13 September 2009 through 17 September 2009.
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Konferensbidrag (refereegranskat)abstract
- Printers may show a substantial ultrafine particles (UFP) generation for short printing periods.To evaluate efficient strategies for control of printer pollution, the present paper examines thecleaning performance and economical benefit of a combination between portable electrostaticair cleaners (AC) and ventilation. The study is based on both field experiments and experimentsin a test chamber. A particle number balance model was also built up. It shows that, with thesame sum of ventilation air flow rate (Qv) and AC clean air delivery rate (CADR), if no outdoorpollution influence, the cleaning performance is constant. The measurements indicate thatalthough the particle exposure (e.g. average concentration) may be strongly reduced by addingan air cleaner with sufficient CADR, the maximum (peak) concentration is not reduced to thesame extent. Considering the saving of ventilation operation cost the economical benefit of ACand HVAC combination is clear.
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| 19. |
- Shi, Bingbing, 1983, et al.
(författare)
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Ventilationsfilter och ultrafina partiklar
- 2013
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Ingår i: Energi och Miljö. ; :Nr. 4, 2013., s. ss. 56-58
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Under senare år har flera medicinska och miljömedicinska studier pekat på att så kallade ultrafina partiklar kan vara farligare än andra, större, partiklar. Dessvärre tar varken Svensk Standard för provning och klassning av ventilationsfilter eller SP:s P -märkning av filter någon hänsyn till så små partiklar. Problemet har dock studerats i ett nyligen avslutat forskningsprojekt vid Chalmers i Göteborg.
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