April 3, 2002

HIGH-TEMPERATURE STRENGTH OF CHARGE AIR COOLERS IS CRUCIAL FOR CLEAN DIESEL ENGINES

As governments around the world continue to pressure the makers of diesel engines and heavy-duty trucks to meet increasingly stringent emissions standards, the International Copper Association's CuproBraze® technology is likely to play a key role in the design of temperature-resistant heat exchangers. On May 3, 2002 the U.S. Federal Appeals Court in Washington, D.C., upheld the Environmental Protection Agency rule that calls for greatly reduced diesel emissions by 2007. In doing so, the court supported the opinion of the EPA that diesel makers could develop the needed technology according to the timetable initially set by the EPA in January 2001.

Most diesel engine manufacturers agree that clean diesel engines will require more complex turbochargers and heat exchangers than in the past. More heat at higher temperatures will need to be removed to gain control over the combustion processes. The use of CuproBraze® technology greatly changes the design parameters for charge air coolers (CACs) and turbochargers. A copper-brass CAC can withstand high inlet temperatures, retaining much of its strength and avoiding metal fatigue.

Aluminum tubes in current-generation CACs are unreliable above 180 °C, and the maximum temperature specifications for aluminum CACs typically are even lower. Above 200 °C the strength of aluminum drops 40 to 60 percent compared to its strength at 150 °C, and serious problems can occur as a result.

High-temperature performance is not the only reason to choose CuproBraze® instead of aluminum for CACs. Another advantage is the lower airside pressure drop. It is estimated that a copper-brass heat exchanger will have a 20 to 30 percent lower air pressure drop compared to aluminum. Other heat exchanger applications in clean diesel engines may benefit from a same-sized copper-brass heat exchanger with higher heat rejection than an aluminum heat exchanger, or a smaller copper-brass heat exchanger with the same performance.

New clean-burning diesel engines will soon become nearly as clean as gasoline engines, thanks to the EPA's mandate that requires particulate matter, oxides of nitrogen, nonmethane hydrocarbons and other pollutants to be reduced substantially by 2007. In addition to forcing changes in heavy-duty vehicles, this action has positive implications for consumers. Increased use of diesel engines in SUVs, minivans and light trucks can be expected as the technology for emissions reduction is improved,  and consumers will benefit from the greater fuel efficiency and durability of diesel engines compared to gasoline engines — not to mention a cleaner environment.

CuproBraze® technology was developed by the International Copper Association and is licensed without cost to qualified manufacturers. For more information, contact Alea@copper.org.

Note: The Environmental Protection Agency’s proposal pertaining to diesel fuels and emission standards for heavy-duty vehicles is now a final rule, which was published January 18, 2001 in the Federal Register (pp. 5001-5193). The entire document is available in PDF or electronic-text format from the Federal Register Online via Government Printing Office (GPO) access (http://www.gpo.gov).