AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Characterizing a Two-Angle Light Scattering Instrument for Concentration and Size Measurement of Diesel Particulates with Intra-Cycle Time Resolution
POOYAN KHEIRKHAH, Jeff Farnese, Patrick Kirchen, Steven Rogak, University of British Columbia
Abstract Number: 620 Working Group: Combustion
Abstract To measure the concentration and size of the carbonaceous particulate emissions from a direct-injection engine, a new instrument that measures the light scattering in two angles is used. The Fast Exhaust Nephelometer (FEN) has a short sampling tube to minimize the transfer time from the engine exhaust pipe to the FEN chamber. It samples close to the engine exhaust valve; therefore, its measurement time resolution is close to 1 milliseconds, much shorter than an engine cycle. This is the first instrument of this type with the ability to measure the intra-cycle particulate matter from successive engine cycles. By using the ratio of the scattered light power in two angles, the mass concentration and the median diameter of the particulates are calculated based on the Rayleigh-Debye-Gans (RDG) theory.
The mass concentration measurements from the FEN correlated well with the diluted exhaust measurements sampled by the Dusttrak-DRX. The particle size of the diluted samples measured with the FEN were very similar to the previously reported data from the same engine. However, the median gyration diameter of the undiluted exhaust, taken near the exhaust valve, were 40-70 nm smaller compared to the diluted particles based on the RDG model. Calculations based on estimated particle number concentration and exhaust flow residence time in this engine suggests that the particle coagulation inside the pipes and the exhaust surge tank probably causes this size growth. To confirm the validity of the RDG model and the accuracy of the FEN, the instrument is used to measure the concentration and size of laboratory-generated aerosols. In particular, analysis of the NaCl aerosols with a Scanning Mobility Particle Spectrometer (SMPS) and the FEN were compared against each other.