CCJ

March 2015

Fleet Management News & Business Info | Commercial Carrier Journal

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COMMERCIAL CARRIER JOURNAL | MARCH 2015 59 T he next generation of heavy- duty diesel engine design is driven by the U.S. Environ- mental Protection Agency's greenhouse gas emissions regulations that limit the amount of carbon dioxide and other exhaust gases that the agency feels contribute to global warming. For OEMs, the focus of the new regula- tions is not on mitigating climate change, but rather on fuel economy. Industry ex- perts say it makes sense to view the GHG regulations as a stealth move leading to the first fuel economy standards for heavy-duty and vocational diesel engines. One possible approach to greater die- sel engine efficiency is the use of waste heat recovery systems, a technology mentioned in EPA's published GHG 2017 guidelines that outline credit pro- grams for manufacturers. Among those credits is one "intended to promote implementation of advanced tech- nologies such as hybrid powertrains, engines with Rankine cycle waste heat recovery systems, and electric or fuel cell vehicles." But what is a waste heat recovery system? How does it work? Is it viable for diesel truck engines? A promising boost Today's diesel engines have a heat efficiency rating of about 44 percent – meaning that nearly half of the energy potential present in a gallon of fuel ends up in the flywheel as available power after the combustion process. The rest of that potential energy – the other roughly 56 percent – is lost. "It comes out the combustion process as vaporized water and exhaust heat, although a certain balance goes into the cooling system to keep engine tempera- tures in check," says Tony Greszler, vice president of government and industry relations for the Volvo Group. The concept of waste heat recovery dates to the beginning of the Machine Age when steam engine designers real- ized the inefficiency of their creations. Steam engines work by heating water to create high-pressure steam that is pushed through a cylinder to create power. "The concept is older than the diesel engine," Greszler says. "But the concept of applying it to a diesel, essentially as a secondary engine cycle, is what's new." Cummins has been at the forefront in developing waste heat recovery systems and has shown them to be a viable tech- nology in laboratory demonstrations and truck installations, including the Cum- mins-led SuperTruck program funded by the U.S. Department of Energy. Satish Chandra, the company's director of advanced systems integration, says the SuperTruck – equipped with Cummins' prototype waste heat recovery system and in 24-hour head-to-head testing against a 2009 baseline truck – demonstrated a 75 percent increase in fuel economy, a 43 percent reduction in GHG emissions and an 86 percent gain in freight efficiency. "In Cummins' experience, the technol- ogy is very attractive and viable when fully integrated in the vehicle system to boost fuel economy and support other energy needs such as driver comfort," Chandra says. Stede Granger, OEM technical man- ager for Shell Lubricants, says a waste heat recovery system and a hybrid drive system work in a similar fashion. When a An old theory finds new life – but will it work for every trucking application? BY JACK ROBERTS The Peterbilt-Cummins SuperTruck team integrated a waste heat recovery system in two demonstration vehicles as part of its 50 percent efficient engine package, which involved Cummins' ISX15 engine.

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