Comparison of Filter Smoke Number and Elemental Carbon Mass From Partially Premixed Low Temperature Combustion in a Direct-Injection Diesel Engine

Abstract

Partially premixed low temperature combustion (LTC) is an established advanced engine strategy that enables the simultaneous reduction of soot and NO, emissions in diesel engines. Measuring extremely low levels of soot emissions achievable with LTC modes using a filter smoke meter requires large sample volumes and repeated measurements to achieve the desired data precision and accuracy. Even taking such measures, doubt exists as to whether filter smoke number (FSN) accurately represents the actual smoke emissions emitted from such low .wot conditions. The use of alternative fuels such as biodiesel also compounds efforts to accurately report soot emissions since the refiectivity of high levels of organic matter found on the particulate matter collected may result in erroneous readings from the optical detector Using FSN, it is desired to report mass emissions of soot using empirical correlations derived for use with petroleum diesel fuels and conventional modes of combustion. The work presented in this paper compares the experimental results of well known formulas for calculating the mass of soot using FSN and the elemental carbon mass using thermal optical analysis (TOA) over a range of operating conditions and fuels from a four-cylinder direct-injection passenger car diesel engine. The data show that the mass of soot emitted by the engine can be accurately predicted with the smoke meter method utilizing a 3000 ml sample volume over a range of FSN from 0.02 to 1.5. Soot mass exhaust concentration calculated from FSN using the best of the literature expressions and that from TOA taken over all conditions correlated linearly with a slope of 0.99 and R^ value of 0.94. A primary implication of the work is that the level of confidence in reporting the soot mass based on FSN for low soot formation regimes such as LTC is improved for both petroleum diesel and biodiesel fuels.

Volatility characterization of nanoparticles from single and dual-fuel low temperature combustion in compression ignition engines

“…Soot mass emissions from the PPCI engine were measured using an AVL Microsoot photoacoustic analyzer and an AVL 415S Smoke Meter was used for the RCCI engine. Though smoke meter measurements have been shown to be comparable to soot mass concentration even at very low levels found in LTC modes (Northrop et al 2011b), such information for the photoacoustic analyzer is sparse. Future work is required to validate the accuracy of Microsoot measurements for low elemental carbon LTC particles.…”

Evolution and current understanding of physicochemical characterization of particulate matter from reactivity controlled compression ignition combustion on a multicylinder light-duty engine

“…28 Since light-absorbing organics such as polycyclic aromatic hydrocarbons (PAHs) can alter reflectance, 29 low soot and highly condensable aromatic hydrocarbon (HC) concentrations in the exhaust can make interpretation of FSN difficult. For such conditions, Northrop et al 30 found that using a sample volume of 3000 mL over an FSN range of 0.02-1.5 was . (a) NOx and soot formation in local equivalence ratio (F) versus local temperature space and (b) conceptual model of mixing limited diesel combustion illustrating the locations of NOx and soot formation 4 adapted from Kitamura et al 5 adequate for correlating FSN to soot mass for premixed charge compression ignition (PCCI) combustion with conventional fuels and biofuels.…”

Black carbon from ships: a review of the effects of ship speed, fuel quality and exhaust gas scrubbing

“…Filter based light absorption requires significant calibration and corrections and may also suffer from organic particulate and particle size biases Bond et al, 1999;Kondo et al, 2009;Lack et al, 2008a;Nakayama et al, 2010). A common technique for measuring the opacity created by engine exhaust smoke, the filter smoke number (FSN), is a filterbased absorption method that requires substantial empirical corrections to derive BC mass (Northrop et al, 2011). Uncertainties on mass derived from FSN measurements are therefore dependent on the fit to empirical data.…”

“…The FSN is a unitless number derived from filter based light absorption. The measurement technique has known biases (Northrop et al, 2011) that can, in principle, be corrected (Christian et al, 1993) and then translated into BC concentrations. We apply the Christian et al (1993) correction to all the FSN data in this review to produce a BC FSN mass emission factor.…”