AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
On the Black Carbon Content of Soot from Flames and Engine Exhaust
MATTI MARICQ, Ford Motor Company
Abstract Number: 340 Working Group: Combustion
Abstract Black carbon is of environmental interest for its contributions to climate change, air quality, and visibility. Its predominant source is from combustion; thus, it represents an important component of PM emissions from power plants, motor vehicles, aircraft, construction and agricultural equipment as well as biomass burning.
The solid carbonaceous component of combustion PM is variously described as soot, elemental carbon (EC), and black carbon (BC). The latter two generally reflect the measurement method, with EC relying on oxidation of soot into CO2 and BC relying on optical absorption. Often these terms are used interchangeably, not just colloquially but with practical implications. The latter is illustrated by the reliance on instruments such as the photo-acoustic soot sensor, laser induced incandescence, and the smoke meter to serve as the basis of soot measurements in engine exhaust. And conversely, soot is being looked at as a standard material for the calibration of PM measurement instruments.
It is known that condensation of organic material will modify the relationship between soot and BC. However, a recent study (Mamakos et al. Aerosol. Sci. Technol. 47, 927, 2013) revealed that even after volatile removal with a catalytic stripper the BC from a commercial propane diffusion flame soot generator (Combustion Aerosol Standard) was generally lower than the EC. The work presented here will examine in more detail the relationship between BC and soot mass from premixed and diffusion flames, and in motor vehicle exhaust. This reveals that the BC content increases with the age of the soot in the flame, likely due to increased carbonization. Motor vehicle soot has a high BC content, which is attributed to the higher temperature environment of engine combustion. The results have implications on the use of optical methods to measure PM emissions and the use of soot for instrument calibration.