Development and Application of Emerging Engine Exhaust Aerosol Measurement Technologies

The objectives of this research are to improve the understanding of variables like dilution and sampling conditions that contribute to particle-based emission measurements, to identify and improve current and emerging methods, and to use alternative methods to make measurements of engine exhaust to further elucidate the impact of fuels, emission control and engine state-of-maintenance on emissions.;Chapter 3 improves the understanding of variables like dilution and sampling conditions that contribute to particle-based emission measurements by assessing and comparing the nucleation tendency of Diesel aerosols when diluted with a porous wall dilutor or an air ejector in a laboratory setting. A de facto standard air-ejector dilutor and typical dilution conditions were used to establish the baseline sensitivity to dilution conditions for the given engine operating condition. A porous tube dilutor was designed and special attention was given to integrating the dilutor with the exhaust pipe and residence time chamber. Results from this system were compared with the ejector dilutor.;Chapter 4 describes the comparison of two methods that are used to separate the solid and volatile components of an aerosol: the thermal denuder (TD) and catalytic stripper (CS). The TD and CS were challenged with atmospheric and laboratory generated aerosols. Laboratory generated particles were composed of tetracosane, tetracosane and sulfuric acid, and dioctyl sebacate and sulfuric acid. These compositions were chosen because they roughly simulate the composition of nanoparticles found in Diesel exhaust. The TD method produced semi-volatile particle artifacts due to the incomplete removal of evaporated compounds that nucleated and formed particles and solid particle artifacts that formed during treatment of the aerosol by the TD. Fundamental differences in the performance of the two methods lead to different conclusions regarding the presence or absence, size, and concentration of solid particles in Diesel exhaust.;In Chapter 5 the physical and chemical nature of the engine exhaust from a Formula SAE spark ignition engine was evaluated using two competition fuels, 100 octane race fuel and E85. Three engine conditions were evaluated: 6000 RPM 75% throttle, 8000 RPM 50% throttle, and 8000 RPM 100% throttle. Diluted emissions were characterized using a Scanning Mobility Particle Sizer (SMPS) and a Condensation Particle Counter (CPC). E85 fuel produced more power and produced less particulate matter emissions at all test conditions, but more fuel was consumed.;Chapter 6 demonstrates how exhaust aerosol measurements can be used to diagnose an engine fault in a Diesel engine. A cyclic variation in total particle number concentration was observed while making routine exhaust emission measurements. Many dilution and engine operating conditions were examined and by sequentially shutting down individual cylinders the problem was traced to cylinder 2. The engine was disassembled and piston 2's oil control ring was found to be fractured. Replacement of the ring eliminated the particle concentration fluctuation. This chapter presents the results of experimental measurements made to determine the cause of the irregular emissions.;Chapter 7 describes the results of three experiments performed with Continuously Regenerating Traps (CRTs) in a controlled laboratory setting to elucidate the effects of fuel sulfur content, filter age, and storage and release effects on particle concentration. In the first experiment, a new CRT was evaluated using near zero sulfur Fischer Tropsch fuel and low sulfur lubricating oil (420 ppm). The objective was to measure particle emissions from an emission control device that had not previously been exposed to sulfur under a variety of operating and dilution conditions. Next, a used CRT was evaluated using the same fuel and lubricating oil. Finally, the used uncatalyzed Diesel particulate filter (DPF) from the used CRT was replaced with a new, uncatalyzed DPF. The emissions from the used Diesel oxidation catalyst (DOC) + new DPF configuration were evaluated and compared to those of the used CRT. (Abstract shortened by UMI.)...