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  1. Article ; Online: Correction to Dynamic Analysis of Particle Emissions from FDM 3D Printers through a Comparative Study of Chamber and Flow Tunnel Measurements.

    Ding, Shirun / Wan, Man Pun / Ng, Bing Feng

    Environmental science & technology

    2021  Volume 55, Issue 13, Page(s) 9396

    Language English
    Publishing date 2021-06-23
    Publishing country United States
    Document type Published Erratum
    ISSN 1520-5851
    ISSN (online) 1520-5851
    DOI 10.1021/acs.est.1c03684
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Infection risk of SARS-CoV-2 in a dining setting: Deposited droplets and aerosols.

    Ding, Shirun / Lee, Jia Shing / Mohamed, Mohamed Arif / Ng, Bing Feng

    Building and environment

    2022  Volume 213, Page(s) 108888

    Abstract: Considering that safe-distancing and mask-wearing measures are not strictly enforced in dining settings in the context of SARS-CoV-2, the infection risks of patrons in a dining outlet (e.g., a cafe) is assessed in this study. The size-resolved aerosol ... ...

    Abstract Considering that safe-distancing and mask-wearing measures are not strictly enforced in dining settings in the context of SARS-CoV-2, the infection risks of patrons in a dining outlet (e.g., a cafe) is assessed in this study. The size-resolved aerosol emission rate (AER) and droplets deposition rate (DDR) on dining plates from speaking were obtained through chamber measurements and droplet deposition visualization via fluorescent imaging technique (FIT), respectively. The AER from speaking was 24698 #/min in the size range of 0.3-5.5 μm, while the DDR was 365 #/min in the size range of 43-2847 μm. Furthermore, an infection risk model was adopted and revised to evaluate the infection risk of 120 diners for a "3-h event" in the cafe. In a four-person dining setting around a rectangular table, a diner seated diagonally across an infected person posed the least infection risk due to the deposited droplets on dining plates. The deposited droplets on a dining plate were dominant in possible viral transmission as compared to the long-range airborne route when a diner shared a table with the infected person. Yet, long-range airborne transmission had the potential to infect other diners in the cafe, even resulting in super-spreading events. A fresh air supply of 12.1-17.0 L/s per person is recommended for the cafe to serve 4-20 diners concurrently to minimize infection risks due to aerosols. Current ventilation standards (e.g., 8-10 L/s per person) for a cafe are not enough to avoid the airborne transmission of SARS-CoV-2.
    Language English
    Publishing date 2022-02-10
    Publishing country England
    Document type Journal Article
    ISSN 0360-1323
    ISSN 0360-1323
    DOI 10.1016/j.buildenv.2022.108888
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Aerosols from speaking can linger in the air for up to nine hours.

    Ding, Shirun / Teo, Zhen Wei / Wan, Man Pun / Ng, Bing Feng

    Building and environment

    2021  Volume 205, Page(s) 108239

    Abstract: Airborne transmission of respiratory diseases has been under intense spotlight in the context of coronavirus disease 2019 (COVID-19) where continued resurgence is linked to the relaxation of social interaction measures. To understand the role of speech ... ...

    Abstract Airborne transmission of respiratory diseases has been under intense spotlight in the context of coronavirus disease 2019 (COVID-19) where continued resurgence is linked to the relaxation of social interaction measures. To understand the role of speech aerosols in the spread of COVID-19 globally, the lifetime and size distribution of the aerosols are studied through a combination of light scattering observation and aerosol sampling. It was found that aerosols from speaking suspended in stagnant air for up to 9 h with a half-life of 87.2 min. The half-life of the aerosols declined with the increase in air change per hour from 28 to 40 min (1 h
    Language English
    Publishing date 2021-08-08
    Publishing country England
    Document type Journal Article
    ISSN 0360-1323
    ISSN 0360-1323
    DOI 10.1016/j.buildenv.2021.108239
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Dynamic Analysis of Particle Emissions from FDM 3D Printers through a Comparative Study of Chamber and Flow Tunnel Measurements.

    Ding, Shirun / Wan, Man Pun / Ng, Bing Feng

    Environmental science & technology

    2020  Volume 54, Issue 22, Page(s) 14568–14577

    Abstract: Ultrafine particle emissions originating from fused deposition modeling (FDM) three-dimensional (3D) printers have received widespread attention recently. However, the obvious inconsistency and uncertainty in particle emission rates (PERs, #/min) ... ...

    Abstract Ultrafine particle emissions originating from fused deposition modeling (FDM) three-dimensional (3D) printers have received widespread attention recently. However, the obvious inconsistency and uncertainty in particle emission rates (PERs, #/min) measured by chamber systems still remain, owing to different measurement conditions and calculation models used. Here, a dynamic analysis of the size-resolved PER is conducted through a comparative study of chamber and flow tunnel measurements. Two models to resolve PER from the chamber and a model for flow tunnel measurements were examined. It was found that chamber measurements for different materials underestimated PER by up to an order of magnitude and overestimated particle diameters by up to 2.3 times, while the flow tunnel measurements provided more accurate results. Field measurements of the time-resolved particle size distribution (PSD) in a typical room environment could be predicted well by the flow tunnel measurements, while the chamber measurements could not represent the main PSD characteristics (e.g., particle diameter mode). Secondary aerosols (>30 nm) formed in chambers were not observed in field measurements. Flow tunnel measurements were adopted for the first time as a possible alternative for the study of 3D printer emissions to overcome the disadvantages in chamber methods and as a means to predict exposure levels.
    MeSH term(s) Aerosols ; Air Pollution, Indoor/analysis ; Particle Size ; Particulate Matter ; Physical Phenomena
    Chemical Substances Aerosols ; Particulate Matter
    Language English
    Publishing date 2020-11-02
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ISSN 1520-5851
    ISSN (online) 1520-5851
    DOI 10.1021/acs.est.0c05309
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: A CFD-sectional algorithm for population balance equation coupled with multi-dimensional flow dynamics

    Shang, Xiaopeng / Ding, Shirun / Ng, Bing Feng / Wan, Man Pun

    Powder technology. 2020 Feb. 15, v. 362

    2020  

    Abstract: A novel CFD-sectional algorithm is developed to address the challenges in the existing sectional simulations coupled with multi-dimensional fluid dynamics, including solution of complex sectional coefficients, serious computational burden for lots of ... ...

    Abstract A novel CFD-sectional algorithm is developed to address the challenges in the existing sectional simulations coupled with multi-dimensional fluid dynamics, including solution of complex sectional coefficients, serious computational burden for lots of coupled partial differential equations, and nonlinear source terms. The sectional coefficients are specified by a numerical quadrature with adaptive integration limits, which proves to be computationally efficient and accurate. The inter-equation coupling is treated by hybrid-segregated procedures and the source term is linearized by the operator splitting method. The CFD-sectional algorithm is validated against a self-preserving solution of particles undergoing Brownian coagulation. The acoustic agglomeration in a standing wave is simulated as a representative case. It has been demonstrated that the predictions regarding the particle size distribution and agglomeration process agree well with the experimental data, which verifies the capability of the developed CFD-sectional algorithm in simulating the spatially inhomogeneous population balance equation coupled with multi-dimensional flows.
    Keywords acoustics ; algorithms ; coagulation ; differential equation ; hydrodynamics ; particle size distribution ; powders ; prediction
    Language English
    Dates of publication 2020-0215
    Size p. 111-125.
    Publishing place Elsevier B.V.
    Document type Article
    ISSN 0032-5910
    DOI 10.1016/j.powtec.2019.11.084
    Database NAL-Catalogue (AGRICOLA)

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  6. Article: The characteristics and formation mechanisms of emissions from thermal decomposition of 3D printer polymer filaments

    Ding, Shirun / Ng, Bing Feng / Shang, Xiaopeng / Liu, Hu / Lu, Xuehong / Wan, Man Pun

    Science of the total environment. 2019 Nov. 20, v. 692

    2019  

    Abstract: Ultrafine particles (UFP) and volatile organic compounds (VOC) emitted from fused deposition modelling (FDM) 3D printing have received widespread attention. Here, we characterize the formation mechanisms of emissions from polymer filaments commonly used ... ...

    Abstract Ultrafine particles (UFP) and volatile organic compounds (VOC) emitted from fused deposition modelling (FDM) 3D printing have received widespread attention. Here, we characterize the formation mechanisms of emissions from polymer filaments commonly used in FDM 3D printing. The temporal relationship between the amount and species of total VOC (TVOC) at any desired operating thermal condition is obtained through a combination of evolved gas analysis (EGA) and thermogravimetric analysis (TGA) to capture physicochemical reactions, in which the furnace of EGA or TGA closely resembles the heating process of the nozzle in the FDM 3D printer. It is generally observed that emissions initiate at the start of the glass transition process and peak during liquefaction for filaments. Initial increment in emissions during liquefaction and the relatively constant decomposition of products in the liquid phase are two main TVOC formation mechanisms. More importantly, low heating rate has the potential to restrain the formation of carcinogenic monomer, styrene, from ABS. A TVOC measurement method based on weight loss is further proposed and found that TVOC mass yield was 0.03%, 0.21% and 2.14% for PLA, ABS, and PVA, respectively, at 220 °C. Among TVOC, UFP mass accounts for 1% to 5% of TVOC mass depending on the type of filaments used. Also, for the first time, emission of UFP from the nozzle is directly observed through laser imaging.
    Keywords carcinogenicity ; emissions ; furnaces ; glass transition ; heat ; image analysis ; liquefaction ; liquids ; models ; polymers ; printers ; styrene ; thermal degradation ; thermogravimetry ; volatile organic compounds ; weight loss
    Language English
    Dates of publication 2019-1120
    Size p. 984-994.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2019.07.257
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 949: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  7. Article ; Online: The characteristics and formation mechanisms of emissions from thermal decomposition of 3D printer polymer filaments.

    Ding, Shirun / Ng, Bing Feng / Shang, Xiaopeng / Liu, Hu / Lu, Xuehong / Wan, Man Pun

    The Science of the total environment

    2019  Volume 692, Page(s) 984–994

    Abstract: Ultrafine particles (UFP) and volatile organic compounds (VOC) emitted from fused deposition modelling (FDM) 3D printing have received widespread attention. Here, we characterize the formation mechanisms of emissions from polymer filaments commonly used ... ...

    Abstract Ultrafine particles (UFP) and volatile organic compounds (VOC) emitted from fused deposition modelling (FDM) 3D printing have received widespread attention. Here, we characterize the formation mechanisms of emissions from polymer filaments commonly used in FDM 3D printing. The temporal relationship between the amount and species of total VOC (TVOC) at any desired operating thermal condition is obtained through a combination of evolved gas analysis (EGA) and thermogravimetric analysis (TGA) to capture physicochemical reactions, in which the furnace of EGA or TGA closely resembles the heating process of the nozzle in the FDM 3D printer. It is generally observed that emissions initiate at the start of the glass transition process and peak during liquefaction for filaments. Initial increment in emissions during liquefaction and the relatively constant decomposition of products in the liquid phase are two main TVOC formation mechanisms. More importantly, low heating rate has the potential to restrain the formation of carcinogenic monomer, styrene, from ABS. A TVOC measurement method based on weight loss is further proposed and found that TVOC mass yield was 0.03%, 0.21% and 2.14% for PLA, ABS, and PVA, respectively, at 220 °C. Among TVOC, UFP mass accounts for 1% to 5% of TVOC mass depending on the type of filaments used. Also, for the first time, emission of UFP from the nozzle is directly observed through laser imaging.
    Language English
    Publishing date 2019-07-17
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2019.07.257
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    In stock of ZB MED Cologne/Königswinter

    Zs.A 949: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  8. Article: Comparative study of combustion and emissions of kerosene (RP-3), kerosene-pentanol blends and diesel in a compression ignition engine

    Chen, Longfei / Anthony Paul Roskilly / Haoye Liu / Shirun Ding / Yanfei Li / Yiji Lu

    Applied energy. 2017 Oct. 01, v. 203

    2017  

    Abstract: Aviation Piston Engines for small general aviation aircrafts are currently facing a transition from being powered by AVGAS (aviation gasoline) to being powered by heavy fuels (diesel or kerosene). The present study compared the combustion and emission ... ...

    Abstract Aviation Piston Engines for small general aviation aircrafts are currently facing a transition from being powered by AVGAS (aviation gasoline) to being powered by heavy fuels (diesel or kerosene). The present study compared the combustion and emission characteristics of diesel, aviation kerosene rocket propellant 3 (RP-3) and RP-3-pentanol blends in a single cylinder compression ignition (CI) engine. Heat release rate, indicated thermal efficiency, ignition delay, combustion duration, and coefficient of variation (COV) of indicated mean effective pressure were experimentally determined to reflect the engine combustion performance. The results demonstrated the feasibility of RP-3 and its mild pentanol blend (20% by volume) in modern CI engines whilst further optimisation of the injection strategy is needed if a higher ratio of pentanol (40% by volume) is used. The discrepancy in terms of combustion and emissions between diesel, RP-3 and its pentanol blends are appreciable, especially for ignition delay, combustion duration and soot emissions. Compared with diesel, RP-3 improved the indicated thermal efficiency by 1.4–12.4%, but pentanol addition decreased that by 1–6.5%. RP-3 and its pentanol blends reduced the soot emissions by nearly an order of magnitude at high engine loads compared with diesel without evident impact on nitrogen oxide (NOx) emissions. Meanwhile, Carbon monoxide (CO) and total hydrocarbon (THC) emissions of RP-3 and its pentanol blends experienced a significant increase at low loads, but CO showed a slight decrease at high loads.
    Keywords aircraft ; aviation ; carbon monoxide ; combustion ; cylinders ; emissions ; gasoline ; heat ; kerosene ; nitrogen oxides ; pentanols ; soot
    Language English
    Dates of publication 2017-1001
    Size p. 91-100.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2000772-3
    ISSN 0306-2619
    ISSN 0306-2619
    DOI 10.1016/j.apenergy.2017.06.036
    Database NAL-Catalogue (AGRICOLA)

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