'Super cell' tests engines at varying altitudes
Southwest Research Institute has developed a "super cell" to evaluate the effects of altitude and other ambient conditions on the performance and exhaust emissions of heavy-duty engines. The cell, at SwRI's facility in San Antonio, Texas, can simulate atmospheric pressures from sea level or below to above 12,000 feet, and combine them with interactions of fuels, lubricants and catalysts.
"Regulatory groups worldwide are concerned that pollutant limits demonstrated in currently prescribed test procedures may be exceeded in day-to-day, real-world applications," said Terry L. Ullman, assistant director of the SwRI Engine and Emissions Research Department.
The U.S. Environmental Protection Agency therefore introduced not-to-exceed (NTE) emission limits that apply to actual operations over a range of real-world conditions encountered by trucks and machinery.
NTE conditions are readily available with precise repeatability in the super cell, which simulates various altitude conditions, along with a range of temperatures and humidity levels, he explained. The cell and its equipment, including a dynamometer and precise instruments, can test on- and off-road engines of 100 to 750 horsepower. So far one truck engine has been tested for an original equipment manufacturer.
"Although these conditions can be assessed to some degree in the field, engine development and calibration efforts are better performed and validated under tightly controlled conditions," said Ullman. "By combining the environmental conditions seen throughout the world into an engine test cell, we can help manufacturers and suppliers meet the challenges of more stringent emission limits for hydrocarbons, carbon monoxide, oxides of nitrogen and particulates."
Although the super cell is designed to help manufacturers comply with NTE limits, it also can be used to optimize engines for fuel economy and performance at conditions not easily achieved in builders' labs.
Combining this capability with precise instrumentation and engine operation, SwRI helps manufacturers evaluate how their engines, fuels and lubricants will operate at high altitudes, such as those in Denver and Mexico City, as well as at lower altitudes. Devices that control emissions or improve performance can also be quantified.
The ability to precisely repeat conditions also relieves concerns about lab-to-lab variability, Ullman said. The super cell's equipment provides emissions data compliant with on- and off-road regulations for current engines and those built for regs taking effect in 2007 and beyond. It can also test for markets outside the U.S. and Canada. Ullman can be reached at (210) 522-2654 or by e-mail at terry.ullmann@swri.org.
