Semester

Summer

Date of Graduation

2008

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Gregory J Thompson

Abstract

Heavy-duty diesel engines (HDDE), because of their widespread use and reputation of expelling excessive soot, have frequently been held responsible for superfluous amounts of overall environmental particulate matter (PM). PM is a considerable contributor to air pollution, and a subject of primary concern to health and regulatory agencies worldwide. The U.S. Environmental Protection Agency (EPA) has provided PM emissions regulations and standards of measurement techniques since the 1980's. PM standards set forth by the EPA for HDDEs are based only on total mass, instead of size and/or concentration. The European Union is considering regulating particle size, and it may influence the U.S. EPA to adopt particle size limits in the future.;The purpose of this research was to better understand the variations in DPM measurements due to fuel alteration or changes in other parameters such as relative humidity and dilution ratio. The Cambustion DMS-500, a fast particle spectrometer, was used to continuously sample diesel aerosol from a HDDE test-cell dilution tunnel. Samples were taken from the primary dilution tunnel and were further diluted in a secondary dilution system. Various fuels were selected to represent available market supplies. Three engines, a 2004 Cummins ISM 370, a 1992 Detroit Diesel DDC S60, and a rebuilt 1992 Detroit Diesel DDC S60, were tested to examine the effects of varying engine technology. Several types of biodiesel and petroleum-based diesel fuels were evaluated in these engines with and without additives. Experiments were performed to determine: the minimum detectable variations in PM concentrations, relative humidity effects, dilution effects, barometric pressure effects, fuel additive effects, sample line temperature effects, and the associations between certain engine operating events and PM concentrations.;The smallest significant variation in concentration that was detected during this research was a 1.51 % increase in 64 nm particles due to the use of a fuel additive. The effects of relative humidity on particle concentrations were only present during low load (less than 50 % of the maximum load) engine operation, and they were generally associated with high levels of run-to-run variation. Nearly doubling the overall dilution ratio was shown to greatly increase nanoparticle (<40 nm) concentrations and slightly increase the concentrations of other particles during certain operation conditions. Barometric pressure change was not directly linked to PM emissions, but it appeared to have caused increased run-to-run variation. In all cases where a fuel additive was used, an increase in the amount of the additive led to a 130 % to -90 % change in the resulting particle concentrations. In addition, a technique was developed for the conversion of continuous DMS data (particle sizes and concentrations) to brake-specific PM mass-flow. According to the gravimetric measurements, the technique was accurate to within 6.24 % for the 1992 DDC S60 engines and 26.4 % for the 2004 ISM 370 engine.

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