Synthetic Auto Exhaust Helps Car Makers Go With The Flow

Why would an environmentally concerned federal agency synthesize auto exhaust?

Scientists at the Commerce Department's National Institute of Standards and Technology have just opened a new facility that simulates auto exhaust in order to help U.S. car makers develop measurement technology necessary to produce low-emission vehicles.

U.S. automobile manufacturers asked NIST to simulate vehicle exhaust so they can calibrate a new type of flow meter that can directly measure exhaust flow from a car's tailpipe. Accurate flow measurements are critical in quantifying levels of exhaust pollutants and for the development of more environmentally friendly cars.

The new Exhaust Meter Calibration Facility is now available to help auto makers measure vehicle emissions more accurately than currently possible. NIST developed the EMCF at the request of the American Industry Government Emissions Research (AIGER) group, which represents Chrysler Corp., Ford Motor Co., General Motors Corp., Navistar International Transportation Corp., the California Air Resources Board and the U.S. Environmental Protection Agency.

The EMCF is one of five NIST projects focused on helping AIGER reduce vehicle emissions. New vehicle emissions limits imposed by the Clean Air Act of 1990 require car manufacturers to measure accurately very low levels of pollutants.

"It is very important for us to have this facility at NIST," says Craig Morgan, an emissions engineer with Chrysler Corp. "Without a NIST traceable calibration, we would not be able to verify the accuracy of our exhaust flow measurements. Emissions measurements are becoming more complex, and we are relying on NIST to provide the expertise in fluid flow measurement that we lack."

The facility, the first of its kind anywhere, simulates auto exhaust by mixing known quantities of nitrogen, carbon dioxide, argon and water vapor. If required, low levels of gases such as carbon monoxide and hydrocarbons also can be included.

The EMCF can measure the combined flow with less than 1 percent uncertainty and can simulate flows of one to 100 standard liters per second, the range of interest to vehicle manufacturers. The ratio of the gases can be changed, and the temperature may be varied from 290 to 700 Kelvin (or about room temperature to 800 degrees Fahrenheit). The facility is computer controlled for automated data collection at predetermined temperatures, flows and compositions.

It is expected to be a focal point for research to enable accurate exhaust flow measurement by the automotive industry and should be invaluable in developing models to predict how flow measurement technology will respond to changes in composition and temperature which are typical in industrial applications," says NIST engineer John Wright.

For more information on the Exhaust Meter Calibration Facility, contact John Wright of the Fluid Flow Group, Rm. 105, Fluid Mechanics Bldg., NIST, Gaithersburg, Md. 20899-0001, (301) 975-5937, e-mail: john.wright [at] nist.gov (john[dot]wright[at]nist[dot]gov).

As a non-regulatory agency of the Commerce Department's Technology Administration, NIST promotes U.S. economic growth by working with industry to develop and apply technology, measurements and standards.