AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
A Three-Angle Light Scattering Technique for Measuring the Single-Cycle Exhaust Soot from the Internal Combustion Engines
Pooyan Kheirkhah, Patrick Kirchen, STEVEN ROGAK, University of British Columbia
Abstract Number: 798 Working Group: Instrumentation and Methods
Abstract Soot emission from direct-injection engines is rarely steady; a few combustion cycles can dominate the total engine-out soot. Cycle-resolved measurements are currently only achievable with the costly in-cylinder optical methods. The Fast Exhaust Nephelometer (FEN) simultaneously measures the light scattering in three angles to infer the concentration and size of the PM. To develop and calibrate the FEN data processing, a series of measurements were made on steady diluted exhaust in parallel with measurements by SMPS, filter sampling and electron microscopy.
The measured FEN signal is converted to the soot concentration using a new model that incorporates the Rayleigh-Debye-Gans (RDG) and an aggregate model using recent correlations between the primary particle size and the aggregate size. The ratio of the light scattering signals measured in three angles is used to infer the average size, the geometric standard deviation, and the Mass Scattering Coefficient (MSC) of the soot aggregates. Next, the FEN was connected to a heavy-duty engine, sampling near the exhaust valve and synchronized with the engine crankshaft encoder. The response time is measured by disabling and then re-enabling the fuel injection. This high-low-high signal transition during this “skip-firing” scheme indeed shows that the instrument responds to the engine-out soot in less than 40-50 milliseconds, i.e. half of the engine cycle period over a wide range of engine speeds.