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@PHDTHESIS{Bischof:908235,
      author       = {Bischof, Oliver},
      title        = {{A}pplication-{S}pecific {C}alibration of {C}ondensation
                      {P}article {C}ounters under {L}ow {P}ressure {C}onditions},
      volume       = {579},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2022-02478},
      isbn         = {978-3-95806-629-8},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {ix, 137},
      year         = {2022},
      note         = {Dissertation, RWTH Aachen University, 2021},
      abstract     = {Condensation Particle Counters (CPC) are research
                      instruments that are commonly used to measure fine, airborne
                      particles. They are able to determine the particle number
                      concentration of both, the smallest nanoparticles and also
                      larger particles in the accumulation mode, which cannot be
                      measured with optical methods at all or with sufficient
                      accuracy. In the last four decades, CPCs have been
                      increasingly used todetermine particle number concentrations
                      also at non-standard atmospheric pressurein both scientific
                      research as well as for regulatory purposes. Measurement
                      conditionsat reduced pressure require a dedicated
                      calibration of the CPCs to ensure correctresults. The aim of
                      my thesis was to investigate the performance of CPCs at
                      variouslevels of low-pressure by means of a comprehensive
                      and detailed calibration study.In the first part, this
                      thesis reviews details of the CPC technology, explains
                      applicationswith a need for low-pressure calibration and
                      presents an extensive literature review ofthe field. It
                      provides a critical analysis of the papers most relevant to
                      this research,building on a survey of more than 60
                      peer-reviewed publications from the past forty years. The
                      literature review points to contradictions in the
                      understanding of thebehavior of CPCs at low pressure and
                      highlights opposing findings. In a subsequentsection, a
                      numerical model is applied to investigate how reduced
                      pressure conditionsimpact CPC performance in theory. The
                      model delivers a prediction of CPC countingefficiencies as
                      well as d90, d50 and d10 cut-sizes at various levels of
                      reduced pressure.The second part of this thesis describes
                      extensive laboratory experiments and providesa detailed
                      analysis of the performance at reduced pressure. Two
                      different CPC modelswere calibrated for their particle
                      counting efficiency, smallest particle size detectionlimit,
                      and concentration linearity. The calibrations were performed
                      with test aerosols oftwo very different particle sources.
                      One of the calibration aerosols is representative
                      ofinorganic particles in ambient air not impacted by
                      anthropogenic activity. The otheraerosol is freshly
                      generated soot from an inverted-flame burner, which serves
                      as aproxy for combustion emissions found in urban
                      environments. Additionally, all countingefficiency
                      experiments were done with the relative humidity of the
                      calibration aerosolvaried from almost dry to moderate levels
                      of humidity. This aspect was included toconsider that
                      humidity might play a role in the activation of particles
                      inside a CPC.This thesis provides new insights into the
                      experimental method, operating parametersand effective
                      practices to calibrate CPCs for their use under low-pressure
                      conditions.Results demonstrate that in general CPCs work as
                      specified down to a thresholdpressure. Below that point,
                      their performance depends on the exact measurementconditions
                      and the specific CPC design. These findings are an important
                      advancementin understanding the behavior of CPCs at low
                      pressure and can serve as guidancewhen correcting the
                      reported number concentration for the impact of reduced
                      pressure.They also show that a dedicated calibration of CPCs
                      is advisable for every type of lowpressureapplication that
                      requires highly accurate particle number concentration
                      data.},
      cin          = {IEK-8},
      cid          = {I:(DE-Juel1)IEK-8-20101013},
      pnm          = {899 - ohne Topic (POF4-899)},
      pid          = {G:(DE-HGF)POF4-899},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/908235},
}