Measurement of Particulate Matter Mass for Atmospheric Monitoring and Very Low Vehicle Emissions

Doctor of Philosophy, Graduate Program in Mechanical Engineering
University of California, Riverside, December 2017
Dr. Heejung Jung, Chairperson

Many  assessments  of  public  exposure  to  particulate  emissions  associated  with  illness  and  mortality  are  based  on  the  measurements  from  stationary  monitoring  sites.  The  method  raises discrepancies  and  concerns  for  the  real  exposure  near  sources,  such  as  being  on  the  road  and  living near  the  highways.  This  study  explored  the  use  of  a  particle  counter  and  a  diffusion  charger  as  a relatively  simple  means  to  measure  spatiotemporally  resolved  particle  concentrations  over  a  wide region  using  a  mobile  platform  and  accounted  for  traffic  conditions  on  two  major  highways  in Southern  California.  On-road  testing  of  cabin  filtration  systems  for  different  light-duty  vehicles  was studied  using  a  mobile  platform.  A  stationary  monitory  site  was  also  setup  to  study  an  alternative metric  related  to  particle  active  surface  area,  which  is  regarded  as  an  important  metric  to  correlate particle emissions to adverse health effects.  Particle size distributions from scanning mobility particle sizer  during  ambient  monitoring  were  used  to  verify  the  concept.  The  study  found  that  alternative metrics  (number,  surface  area,  and  ratio  of  surface  area  over number)  can  be  used  to  monitor  spatiotemporally resolved particle concentrations over a wide region.

Gravimetric sampling methods on a chassis dynamometer were also studied in accordance to Code of Federal Regulations. The focus this study was to evaluate commercially available partial flow dilutors with a focus on their equivalency with the standard constant volume sampler system and the ability to provide reproducible measurements at low PM emission levels. As PM standards for light-duty  vehicles  are  becoming  more  stringent,  improving the  confidence  and  understanding  the  mass measurement  methods  become  one  of  the  main  focuses  for  the  industry  and  regulatory  agencies. Simultaneous testing was conducted with three partial flow dilutors over the Federal Test Procedure and US06 drive cycles. The Federal Test Procedure had means that were statistically different for two of  the  three  partial  flow  dilutors.  As  for  the  US06  tests,  the  mean  differences  were  not  statistically different.  The  performance  of  all  partial  flow  dilutors  also  showed  repeatable  and  accurate  level  of proportionality, which can easily meet the Code of Federal Regulations 1066 and 1065 requirements for all tests performed.