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Ultrafine Particle Infiltration into Passenger Vehicles. Part II: Model Analysis



Details

  • Personal Author:
  • Description:
    Experimental studies showed that infiltration and passive ventilation are important air exchange mechanisms inside vehicles but previous mathematical models did not consider either one. In this study, we incorporated infiltration and passive ventilation to advance the existing mathematical models and evaluated how different transport mechanisms affect passenger exposures at increasing speeds. Infiltration was formulated using Bernoulli's equation and passive ventilation was derived empirically. The new model describes ultrafine particle (UFP) and carbon dioxide (CO2) transport for a wide range of driving speed under any ventilation conditions. Unlike statistical models, this mathematical model can also provide vehicle-specific and transport mechanism-specific information. The model predictions were in a good agreement with data collected from 10 different vehicle models with an average discrepancy of less than 16% for UFPs and less than 3% for CO2. Under outdoor air (OA) mode, when the fan is off, the model simulation showed that the infiltration and passive ventilation can substantially increase the UFP I/O (in-cabin/on-road concentrations) ratio from 0.15 at 0 km/h to 0.57 at 130 km/h. At medium fan setting, mechanical ventilation dominates and UFP I/O stays at 0.58 regardless of driving speed. Under recirculation (RC) mode, infiltration increases and the RC-mode filtration only removed 44% and 69% of the infiltrated particles at the lowest and medium fan settings, respectively. Model simulations under OA mode show that infiltration starts to occur above 115 km/h with the lowest fan setting; whereas, medium and higher fan settings prevent infiltration up to 145 km/h. [Description provided by NIOSH]
  • Subjects:
  • Keywords:
  • ISSN:
    1361-9209
  • Document Type:
    Text
  • Funding:
    Grant
  • Genre:
    Journal Article
  • Place as Subject:
  • CIO:
    National Institute for Occupational Safety and Health (NIOSH)
  • Topic:
    Workplace Safety & Health
  • Location:
    North America
  • Pages in Document:
    144-155
  • Volume:
    38
  • NIOSHTIC Number:
    nn:20055768
  • Citation:
    Transp Res D Transp Environ 2015 Jul; 38:144-155
  • Contact Point Address:
    Yifang Zhu, Department of Environmental Health Sciences, Jonathan and Karin Fielding School of Public Health, University of California Los Angeles, Los Angeles, CA 90095-1772, USA
  • Email:
    Yifang@ucla.edu
  • Federal Fiscal Year:
    2015
  • Performing Organization:
    University of California Los Angeles
  • Peer Reviewed:
    True
  • Start Date:
    20050701
  • Source Full Name:
    Transportation Research Part D: Transport and Environment
  • End Date:
    20270630
  • Collection(s):
  • Main Document Checksum:
    urn:sha-512:a2be1e92fd2fd185f3634be38fe2a10c4a40ac45c9b66ed470ef2c6fc84f6c8d803cbcc8e0ad911660a1cbecb0bb133cd4967a0322fb090fcfefd964037f960c
  • Download URL:
  • File Type:
    Filetype[PDF - 770.57 KB ]
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