AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Real-time Characterization of Intermediate Volatilty and Semi-Volatile Organic Compound Emissions from a Diesel Engine
EBEN CROSS, Alexander Sappok, James Hunter, Victor Wong, Jesse Kroll, MIT
Abstract Number: 427 Working Group: Combustion
Abstract This paper presents experimental measurements of intermediate volatility and semi-volatile organic compounds (I/SVOCs) emitted from a medium-duty diesel engine under a range of operating conditions. Similar to VOCs, I/SVOCs can impact air quality and climate by serving as precursors to secondary organic aerosol (SOA), but a detailed understanding of such impacts remains incomplete due to a lack of fast, reliable measurement techniques that target I/SVOCs. Here we describe measurements of I/SVOC emissions using a recently-developed technique that combines cryogenic collection and electron-impact high-resolution time-of-flight mass spectrometry. This instrument provides measurements of volatility-resolved mass loading and chemical composition (elemental ratios) of I/SVOCs with ~5-10 minute time resolution. In this experiment, I/SVOC emissions from a dynamometer-controlled Cummins (5.9 L) 2002 ISB 300 engine were measured across a range of engine operating conditions. I/SVOC emissions were characterized during both steady-state and transient conditions to obtain a representative picture of the I/SVOC emission profile of the engine. Transient operating conditions included numerous cold starts as well as changes in engine speed and load representative of on-road driving cycles. Results underscore the importance of transient emissions to the overall I/SVOC emission profile. Analysis of the high-resolution mass spectra reveal evolving hydrocarbon and oxygenated hydrocarbon signatures as a function of engine block temperature (i.e. cold starts) and engine load. The engine test-bed also allowed for the characterization of the influence of a diesel particulate filter (DPF) on the I/SVOC emission profile. I/SVOCs were characterized downstream of the DPF during soot-loading and DPF-regeneration cycles. The sampling apparatus was also equipped with a burner system that was used to characterize the I/SVOC emissions resulting from combustion of ultra-low sulfur diesel (ULSD) fuel and biodiesel fuel.