Improving engine emissions

May 16, 2005

Researchers at Kettering will use a National Science Foundation grant to determine levels of particulate matter emitted by diesel engines, spark ignited engines, jet engines and in hydrogen production, to help manufacturers improve emissions and meet new EPA regulations.

The order is in and the equipment should arrive soon. More than $260,000 worth of machines that measure low-mass particulate matter and the chemical composition of emissions in engines will be installed in the Advanced Engine Research Laboratory (AERL) at Kettering for research related to reducing particulate matter (PM) in emissions, particularly in diesel engines. The MEXA-1370PM -- Super-Low-Mass Particulate Matter Analyzer is made by Horiba, worldwide producer of research measurement systems for motor vehicle manufacturers, government agencies and oil companies.

Greg Davis, professor of Mechanical Engineering and director of the AERL, said the equipment purchase was made possible through a National Science Foundation (NSF) grant for major research instrumentation. "It will allow us to measure ultra low levels of particulate matter in emissions and their chemical composition," he said, "and conduct research in this emerging area in an effort to reduce the adverse impacts of PM emissions on public health and the environment."

PM exhaust emissions from engines used in transportation have been linked to adverse health affects in humans and animals. Diesel engine exhaust has undergone much scrutiny in relation to the role of diesel PM emissions in causing cancer.

Diesel engines currently account for about 25 percent of vehicle (mobile source) PM emissions. Davis predicts that as new Environmental Protection Agency (EPA) emission regulations take effect, this level will substantially decrease, leading many investigators to begin looking at other sources of PM emissions to help reduce PM pollutants. For example, studies area already underway to determine the role of gasoline engines in PM emissions.

Reducing emissions in jet engines is also becoming a higher priority nationwide. Jet engine emissions are especially problematic as airports are typically located in urban areas where concentrations of PM emissions are higher.

Snowmobiles and other off-road vehicles have also come under additional scrutiny for their contributions to emissions pollution. A snowmobile with a conventional two-stroke engine emits approximately 36 times more carbon monoxide and 98 times more hydrocarbons than an automobile.

Research to improve diesel emissions is important in a time of rising fuel costs because they are a feasible solution now and in the near future, according to Davis. "We have an infrastructure already in place," he said, compared to fuel cells as a transportation alternative "for which we don't have any hydrogen fuel infrastructure."

"Fuel cell vehicles are strictly in the research stages, they are at least 20-50 times more expensive than spark ignited engines, and they also have difficulty running in cold weather. All of this makes fuel cell vehicles a long-term potential solution," he added. For the short term, making improvements in more fuel efficient spark ignited engines like diesel engines is a better option, according to Davis.

Emissions from diesel engines have been regulated on a total mass basis for some time, and manufacturers have already worked to decrease the total mass of these emissions. However, the new EPA regulations will require a decrease the PM limits in diesel exhaust by about 90 percent, going from the current regulation of 0.1 grams per brake-horsepower-hour (g/bhp-hr) to 0.01 g/bhp-hr for diesel engines in the 2007 model year, according to Davis.

"The new standards have caused concern industry-wide because PM levels are extremely difficult to measure with precision using the current gravimetric approach," said Davis. In a gravimetric approach a diluted exhaust sample is drawn though a filter that traps the particulate matter and the total PM mass is then determined by measuring the change in filter mass. "As engines produce less PM, it has become increasingly difficult to accurately measure the mass of PM emissions produced using the traditional gravimetric approach," he added.

The newly developed instrumentation purchased for the AERL allows for the accurate measurement of ultra low mass emissions levels down to 0.2 g. This instrumentation also provides a determination of the major components of the PM sample-soot, soluble organic fraction (SOF), and sulfates and will allow the AERL to conduct research into the effects of alternative fuels and after treatment systems in the reduction of engine emissions.

"The work undertaken in the first four areas is an extension of existing research that has been conducted by the AERL," said Davis. "The remaining two areas will be new research efforts that were not previously possible without the new equipment."

Anticipated research projects include determining:

  • the effect of different fuels and operating conditions on the composition of PM exhaust emissions from both spark-ignited (gasoline) and diesel engines,
  • the effect of biomass based fuel in jet engines and measuring the reduction in emissions from two- and four-stroke snowmobile engines when using biomass derived fuels and lubricants,
  • the composition of PM emitted from a partial oxidation (POX) reformer used in the production of hydrogen,
  • the effect alternative fuels or additives have on the mass and composition of PM emissions from jet engines,
  • if catalytic converters change the PM mass and composition of the exhaust emissions in spark-ignited engines and
  • what effects do diesel particulate filters (DPF) have on PM composition in diesel engines.

Recently, investigators have begun to study the broader health implications of PM emissions, including the effects of diesel PM emissions in exacerbating allergic diseases and asthma. The ultra fine PM levels of soluble organic fraction (SOF), in particular, have been shown to cause increased levels of tissue irritation in animals.

Davis said the acquisition of this system will also greatly aid Kettering University in achieving its educational goals. In addition to increasing research capabilities, the low-mass particulate matter measurement and composition determination system will enable the AERL to integrate research projects into undergraduate and graduate education at Kettering and provide hands-on experiences for Kettering's pre-college program participants. On an annual basis more than 150 pre-college students, 290 undergraduates and approximately 10 graduate students will use the equipment.

Emissions analysis capability has been severely limited with no way to measure engine PM emissions. This instrumentation will allow the university to extend the alternative fuels research in order to develop cost effective and sustainable transportation technologies. Because this PM system has unique capabilities, it is hoped that this system will allow Kettering researchers to partner with their peers from industry in collaborating on advanced research projects. Since this instrumentation is not widely available in the research laboratories of the local industrial automotive industries, it is hoped that the addition of this system will enable the AERL to serve as a resource for meeting the needs of industry.

Written by Dawn Hibbard