In this work, engine-out particulate matter (PM) mass emissions from an off-highway diesel engine measured using a low-cost photometer, scanning mobility particle sizer, elemental versus organic carbon analysis, and a photo-acoustic analyzer are compared. Tested engine operating modes spanned the range of those known to result in high semi-volatile particle concentration and those that emit primarily solid particles. Photometer measurements were taken following a primary dilution stage and a sample conditioner to control relative humidity prior to the instrument. Results of the study show that the photometer could qualitatively track total particle mass trends over the tested engine conditions though it was not accurate in measuring total carbon mass concentration. Further, the required photometric calibration factor (PCF) required to accurately measure total PM mass changes with the organic carbon (OC) fraction of the particles. Variables that influence PCF include particle effective density, which changes both as a function of particle diameter and OC fraction. Differences in refractive index between semi-volatile and solid particles are also significant and contribute to high error associated with measurement of total PM using the photometer. This work illustrates that it may be too difficult to accurately measure total engine PM mass with a photometer without knowing additional information about the sampled particles. However, removing semi-volatile organic materials prior to the instrument may allow the accurate estimation of elemental carbon mass concentration alone.

The exhaust filtration analysis system (EFA) developed at the University of Wisconsin – Madison was used to perform micro-scale filtration experiments on cordierite filter samples using particulate matter (PM) generated by a spark-ignition direct injection (SIDI) engine fueled with gasoline. A scanning mobility particle sizer (SMPS) was used to characterize running conditions with four distinct particle size distributions (PSDs). The distributions selected differed in the relative number of accumulation versus nucleation mode particles. The SMPS and an engine exhaust particle sizer (EEPS) were used to simultaneously measure the PSD downstream of the EFA and the real-time particulate emissions from the SIDI engine to determine the evolution of filtration efficiency during filter loading. Cordierite filter samples with properties representative of diesel particulate filters (DPFs) were loaded with PM from the different engine operating conditions. The results were compared to understand the impact of particle size distribution on filtration performance as well as the role of accumulation mode particles on the diffusion capture of PM. The most penetrating particle size (MPPS) was observed to decrease as a result of particle deposition within the filter substrate. In the absence of a soot cake, the penetration of particles smaller than 70 nm was seen to gradually increase with time, potentially due to increased velocities in the filter as flow area reduces during filter loading, or due to decreasing wall area for capture of particles by diffusion. Particle re-entrainment was not observed for any of the operating conditions.

High-Pressure Direct-Injection (HPDI) combustion of Natural Gas can reduce the gaseous and Particulate Matter (PM) emissions compared to a conventional diesel engine. Upcoming EPA and EURO emission limits may restrict particle number as well as particle mass. In preparation for these upcoming limits, the PM mass, size and composition was studied from a heavy-duty Cummins ISX engine converted to HPDI operation. To characterize the PM emissions, tests were based around a mid-speed, high-load operating point. Injection timing, equivalence ratio, gas supply pressure, EGR % and diesel injection mass were isolated and varied. PM emissions were characterized by the mobility size distribution, light scattering and filter loading. In addition a novel thermodenuder was used to determine the PM volatile fraction. It was found that EQR and EGR have the greatest effect on PM mass emissions and the correlations between these parameters are evaluated. The mean particles size and number concentrations are again most effected by EGR and EQR with smaller effects from the GRP and diesel pilot. The size distributions of the parameter variations are similar and there are no nucleation mode ultrafine particles observed. The volatile fraction is fairly constant across the parameter variations and is found to be around 18% of the mass and 11% by number of particles at this high load condition.

The purpose of this study was to measure the impact of various sources of petroleum-based and bio-based diesel fuels on regulated emissions and fuel economy in diesel particulate filter (DPF) equipped diesel engines. Two model year 2008 diesel engines were tested with nine fuels including a certification ultra-low sulfur diesel (ULSD), local ULSD, high aromatic ULSD, low aromatic ULSD, and twenty percent blends of biodiesel derived from algae, camelina, soy, tallow, and yellow grease. Regulated emissions were measured over the heavy duty diesel transient test cycle. Measurements were also made of DPF-out particle size distribution and total particle count from a 13-mode steady state test using a fast mobility particle sizer. Test engines were a 2008 Cummins ISB and a 2008 International Maxx Force 10, both equipped with actively regenerated DPFs. Fuel consumption was roughly 2% greater over the transient test cycle for the B20 blends versus certification ULSD in both engines, consistent with the slightly lower energy content of biodiesel. Unlike studies conducted on older model engines, these engines equipped with diesel oxidation catalysts and DPFs showed small or no measurable fuel effect on the tailpipe emissions of total hydrocarbons (THC), carbon monoxide (CO) and particulate matter (PM). No differences in particle size distribution or total particle count were seen in a comparison of certification ULSD and B20 soy, with the exception of engine idling conditions where B20 produced a small reduction in the number of nucleation mode particles. In the Cummins engine, B20 prepared from algae, camelina, soy, and tallow resulted in an approximately 2.5% increase in nitrogen oxides (NO x ) compared to the base fuel. The International engine demonstrated a higher degree of variability for NO x emissions, and fuel effects could not be resolved (p > 0.05). The group of petroleum diesel test fuels produced a range of NO x emissions very similar to that caused by blending of biodiesel. Test cycles where an active regeneration of the DPF occurred resulted in a nearly threefold increase in NO x emissions and a 15% increase in fuel consumption. The full quantification of DPF regeneration events further complicates the accurate calculation of fuel impacts on emissions and fuel consumption.

The influences of ethanol and iso-butanol on gasoline engine performance, engine-out and tailpipe emissions were studied using a General Motors (GM) 2.0L turbocharged gasoline spark ignition direct injection (SIDI) engine. U.S. federal certification gasoline (E0), two ethanol-blended fuels (E10 and E20), and 11.7% iso-butanol blended fuels were tested. Fourier-Transform Infrared (FTIR) spectroscopy was used to measure non-regulated species including methane, ethylene, acetylene, formaldehyde, acetaldehyde, isobutylene, 1,3-butadiene, n-pentane, and iso-octane. A Fast Mobility Particle Sizer (FMPS) spectrometer was used to measure the particle number (PN) size distribution in the range from 5.6 to 560 nm. The regulated emissions total hydrocarbon (THC), carbon monoxide (CO), and oxides of nitrogen (NO x ) were also measured. Both engine-out and tailpipe emissions results are presented as functions of alcohol content. In general, the alcohols tested reduced total PN emissions, with iso-butanol demonstrating the greatest reduction. Increasing ethanol content and iso-butanol increased formaldehyde emissions, with iso-butanol exhibiting the highest increase. Iso-butanol increased iso-butylene emission; however, it reduced emissions of 1,3-butadiene. Within the context of this study, the alcohols did not significantly change the other regulated emissions.

Low-sulfur “clean” diesel fuel has recently been mandated in the U.S. market. However, quality of diesel fuel, particularly the sulfur content, varies significantly in other parts of the world. Due to logistical issues in various theaters of operation, the Army is often forced to rely on local fuel supplies, which exposes vehicles to diesel fuel or jet fuel (JP8) with elevated levels of sulfur. Currently, modern diesel engines typically use cooled Exhaust Gas Recirculation (EGR) to meet emissions regulations. Using high sulfur fuels and cooled EGR has potential to lead to EGR cooler fouling and corrosion of engine components. Therefore, an experimental study has been setup to investigate the EGR heat exchanger condensate in a heavy duty diesel engine running on JP-8 fuel doped with 3512 ppm of sulfur. Gas was sampled from the EGR cooler and analyzed. A Condensate Collection Device (CCD) was developed and setup according to a modified ASTM 3226-73T standard, to perform analysis of sulfur condensate species of SO 2 and H 2 SO 4 in the EGR system. Results have shown that SO 2 values to have the highest concentration of gaseous sulfur species. SO 2 is also shown to increase as sulfur content in JP-8 increases, but not by the same order of magnitude. Results have also shown low levels of H 2 SO 4 from 2–5 ppm with negligible differences while varying sulfur content in JP-8, EGR levels of the engine, and condenser temperatures in the CCD. Due to suspicion that all sulfur has not been accounted for in experiments with the modified CCD, further experiments were performed using a Fourier Transform Infrared (FTIR) emissions bench for gaseous SO 2 emissions and a Differential Mobility Spectrometer (DMS) for particulate size spectrum analysis. FTIR results yielded similar results for gaseous SO 2 as the modified CCD with SO 2 levels increasing as sulfur content in fuel increases but not by the same order of magnitude. While the results from the DMS have shown that increasing sulfur content in JP-8 will increase the particle sizes in the particle size distribution curve. This also translates to an increase in PM mass concentration in the exhaust stream when sulfur content is increased in JP-8 on an engine with and without EGR.

An experimental investigation was performed on the effect of engine speed and EGR (exhaust gas recirculation) on the particle size distribution and exhaust gas emissions in a compression ignition engine fueled with biodiesel derived from soybean. The results obtained by biodiesel fuel were compared to those obtained by petroleum diesel fuel with sulfur contents of 16.3 ppm. The scanning mobility particle sizer (SMPS) was used for size distribution analysis and it measured mobility equivalent particle diameter in the range of 10.4 to 392.4 nm. In addition to the size distribution of the particles, exhaust emissions such as oxides of nitrogen (NO x ), hydrocarbon (HC), and carbon monoxide (CO) emissions and combustion characteristics under different engine operating parameters were investigated. The engine operating parameters in terms of engine speed, EGR, injection pressure, and intake pressure were varied to investigate the individual impact of the operating parameters. As the engine speed was increased for the both fuels, the larger size particles which dominantly contributes particle mass was increased, however total numbers of particle were reduced. Comparing to petroleum diesel fuel, the combustion of biodiesel fuel in the engine reduced particle concentration of relatively larger size where most of the particle mass is found. Moreover, dramatically lower hydrocarbon and carbon monoxide emissions were found at the biodiesel fueled engine. However, the NO x emission of biodiesel fueled diesel engine shows slightly higher concentration compared to diesel fuel at the same injection timing.

Regulatory agencies are becoming increasingly concerned with particulate emissions as the health and environmental effects are becoming better understood. While much research has been performed on diesel engines, little is known about particulate matter (PM) emissions from natural gas internal combustion engines. In this project, tests were conducted on a Waukesha VGF F18 natural gas engine running at full load. PM 10 combustion emissions were collected on Teflon and quartz filters and a scanning mobility particle sizer (SMPS) was used to determine the particle size distribution. Tests were performed at 4, 5, 6, and 7% exhaust oxygen (O 2 ) levels. Overall, it was found that a large number of small particles were emitted from this engine. The total mass based PM emissions were found to be 0.0148 gm/bkW-hr, which is slightly greater than the tier-4 nonroad diesel particulate emissions standard. Particle distributions revealed that the geometric mean diameter (GMD) of the natural gas particles was approximately 30 nm and did not change with air to fuel ratio. Particulate concentrations were found to decrease at leaner engine operating conditions. Results showed a strong correlation between the NOx and particle concentrations, while an inverse correlation between CO and particle concentrations was revealed.

Researchers concerned both with diesel exhaust health effects and with mechanisms of particulate matter (PM) formation have an interest in gaining understanding of PM size distributions from heavy-duty on-road diesel engines. Prior research has been done on particulate size measurement but the results fall short in understanding PM size distributions because of the response time or size range of the instruments used. This study reports the transient size distributions of PM from a 1992 Detroit Diesel Series 60 on an engine dynamometer from a full flow dilution tunnel for a FTP Transient Cycle using a Cambustion ® Differential Mobility spectrometer (DMS 500). The size bins selected for this study for the nucleation and accumulation modes were 20nm and 60nm bins, respectively. The accumulation mode during the accelerations and the nucleation mode during the decelerations were clearly observed from the distributions with respect to time. Distributions were also observed during the test cycle showing the transition between the two modes. From the results obtained from the analysis, no strong correlation between the 60nm particles and engine speed was observed even though higher counts of accumulation particles were observed at the same time that the vehicle activity occurred. Similarly, there was no correlation between the accumulation mode particles and power. When the distributions of nucleation and accumulation mode particles were plotted against each other, there was no correlation or anti-correlation. The average size distributions were also analyzed during the four periods of the FTP Transient cycle and the highest counts were observed during the Los Angeles Freeway (LAF) period. Also, higher counts at the second New York Non Freeway (NYNF) were observed during the cycle.

A study to explore the effect of EGR upon combustion in a light-duty automotive style diesel engine was performed. The engine used in this study was a Mercedes 1.7L 4 cylinder, direct injected turbodiesel with a common rail injection system. The engine was operated at 2500 RPM, 50% load, with constant rail pressure and injection duration. An endoscope imaging system built by AVL, called the VisioScope™, was used to acquire in-cylinder optical images of combustion events. These images were processed to extract soot radiation temperatures and soot volume fraction for each pixel. The results were compared to global engine measurements using piezo-electric pressure transducers, an emissions bench, and a scanning mobility particle sizer (SMPS) to characterize particulates. It was discovered that the optical data correlated well with the global measurements, allowing for in-depth analysis of the mechanisms of emissions formation at three different EGR levels (0%, 10%, 19%). Several conclusions were reached, including the correlation of soot radiation temperature with NO x production and the correlation of soot luminosity with engine-out PM. Each of these factors was determined as a function of EGR level.

Total (volatile plus solid) and solid particle size, number, and mass emitted from a 3.8 kW diesel powered generator were characterized using a Scanning Mobility Particle Sizer (SMPS) that measures the size distribution of particles, and a catalytic stripper that facilitates the measurement of solid particles. The engine was operated at a constant speed for six steady-state engine operations ranging from idle to rated power. The solid particle size distributions were mainly monomodal lognormal distributions in nature reflecting a typical soot agglomerate size distribution with a number mean diameter in the size range from 98 nm to 37 nm as the load decreases from high to low. At idle, M6, however, the solid particle distribution was bimodal in nature with a high number of solid nanoparticles in the sub-20 nm size range. It is likely that these solid particles nucleated later in the combustion process from metallic ash typically present in the lube oil. The total particle size distributions exhibited a bimodal structure only at light load, M5, engine operation, where a high number of volatile nanoparticles were observed. The rest of the operating conditions exhibited monomodal distributions although the nature of the particles was vastly different. For the medium load modes, M2, M3, and M4, the particles were mainly solid particles. For the rated power, M1, and idle, M6, modes of engine operation, significant number of volatile particles grew to a size nearing that of soot particles making the distribution monomodal, similar to that of a solid particle distribution. This shows that monomodal distributions are not necessarily solid particle but they can be strongly dominated with volatile particles if significant particle growth takes place like the case at M1, and M6. The total number and mass concentration were extremely high at engine rated power. The number concentration exceeded 1.2 billion particles per cubic centimeter and the mass exceeded 750 milligrams per cubic meter. The number concentration is more than five orders of magnitude higher than a typical ambient level concentration, and the mass concentration is more than four orders of magnitude higher. It is important to indicate, however, that if the engine power rating is lowered by 35 percent from its designated level, both particle mass and number emissions will be reduced by two orders of magnitude. By measuring total and solid particle size and number concentration of particles, one can calculate other metrics such as surface area and mass to provide detail information about particle emissions. Such information can serve as an important database where all metrics of particle emissions are captured.