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	The ability to test at low and high altitude using a consistent set of instruments, with the same engine setup and control at the same laboratory location, relieves concern for lab-to-lab variability that can introduce additional uncertainty in gaseous and particulate emissions measurements as well as overall engine performance.

As emission regulations become more stringent, lower limits for the following pollutants are required:

• Hydrocarbon

• Carbon monoxide

• Oxides of nitrogen

• Total particulate

In addition to more stringent standards, regulatory groups worldwide share concerns that pollutant limits demonstrated in current prescribed test procedures may be exceeded in day-to-day, real-world applications.
 

EPA's Not-To-Exceed Pollutant Emissions Levels

The U.S. Environmental Protection Agency (EPA) has bolstered assurance that emission levels are held in check by introducing "not-to-exceed" (NTE) limits for pollutant emissions for both the prescribed procedure used for certification of compliance and a broad range of environmental conditions where large truck engines operate.

Varying Environmental Conditions

Environmental conditions of concern combine:

• 50°F to 100°F operating temperature
  and

• 10% to 95%

   relative humidity
  and

• 29.9 to 24.4 in Hg barometric pressure

Although these conditions can be assessed to some degree in the field, engine development and calibration efforts should be performed and validated:

• Under tightly controlled conditions

• Using accurate instrumentation

• Using well-defined engine operation practices

Transient-Capable Testing Super Cell

The Engine and Emissions Research Department at Southwest Research Institute (SwRI) has developed a transient-capable test cell that provides a range of environmental conditions for heavy-duty diesel engine products that meet the challenges of stringent emission control. This "Super Cell" has the capacity to evaluate engines from 100 to 750 hp while applying altitude-like conditions to both engine intake and exhaust during transient and steady-state operation.

The Super Cell uses a full-flow constant volume sampling, gaseous emissions bench, and particulate measurement system to provide emissions data compliant with current and 2007 and beyond highway engine regulations as well as current and future non-road engine regulations.

Conditions within NTE compliance are readily available with the Super Cell, but altitudes as high as 12,000 feet, along with additional variations in temperature and humidity conditions, can be achieved to investigate emission levels and engine performance for engine markets outside the NTE envelope.

Transient torque map responses of a turbocharged diesel engine for low and high altitudes		Snap smoke response with altitude

The ability to evaluate at low and high altitudes using a consistent set of instruments, with the same engine setup and control at the same laboratory location relieves concern for lab-to-lab variability that can introduce additional uncertainty in gaseous and particulate emissions measurements as well as overall engine performance.

For more information about our independent verification and validation services, or how you can contract with SwRI, please contact Daniel Stewart at dstewart@swri.org or (210) 522-3657.

heavy-dutyemissions.swri.org 

| Engine and Vehicle R&D | Engine, Emissions & Vehicle Research Division | SwRI Home |

Southwest Research Institute^® (SwRI^®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 12 technical divisions.

March 19, 2010