Navistar stands firm on commitment to EGR for 2010
November 1, 2008
HUNTSVILLE, Ala. - During the recent dedication of the Navistar engine plant here, several high-ranking executives made themselves available to field questions from trade press editors. Of course, wit...
HUNTSVILLE, Ala. – During the recent dedication of the Navistar engine plant here, several high-ranking executives made themselves available to field questions from trade press editors. Of course, with EPA2010 emissions standards looming, it’s no surprise Navistar’s decision to meet the impending regulations without exhaust aftertreatment was the primary subject of discussion.
Jack Allen, president of Navistar’s engine group, defended his company’s decision to avoid urea-based Selective Catalytic Reduction (SCR), referring to it as “the most onerous aftertreatment solution customers will have ever seen – way more onerous than diesel particulate filters.”
He contended the cost of urea will mitigate any fuel mileage savings offered by re-tuned engines using lower levels of exhaust gas recirculation (EGR) in combination with SCR.
“It is our belief that the total cost of ownership between SCR and non-SCR is going to be indistinguishable to the customer,” he said from the floor of Navistar’s Huntsville, Alabama plant, which is now producing International MaxxForce big bore engines.
When asked if he was concerned about Cummins decision to adopt SCR on its heavy-duty engines, a strategic change of course that was announced in August, Allen said “We stand by our decision – our decision was made independent of Cummins.”
In fact, he said a recent decision by MAN and Scania in Europe to offer a non-SCR Euro 5 engine validates Navistar’s strategy.
Both European manufacturers had already introduced Euro 5-compliant SCR engines, but they announced at the Hanover truck show in September that they would make an EGR option available as well. Euro 5 NOx standards are more restrictive than EPA07 limits, but not as stringent as EPA2010 regulations, Allen said.
“If there had been a great customer acceptance of (SCR), neither one of those companies would have felt compelled to invest the engineering dollars into making a non-SCR version,” he reasoned.
Tim Shick, director of marketing of Navistar’s engine group, was also available to discuss the nuts and bolts of Navistar’s 2010 emissions solution. He said advances in EGR technology have enabled the company to become EPA2010-compliant without SCR, specifically: the development of a High Pressure Common Rail (HPCR) fuel system that will boost fuel pressures to above 30,000 psi; and a metered injection process.
The fuel will be injected in five stages, Shick explained, which reduces the explosive effect of combustion and allows for a more efficient burn, creating less NOx in the first place.
“So we retain fuel economy by making the fuel more burnable, when the engine needs it most at low speeds,” Shick explained of the HPCR fuel system.
He conceded more exhaust gas will have to be recirculated through the engine, to the tune of about 10%. That brings the total EGR rate to about 40%, he explained.
He also responded to concerns the engine will run hotter as a result of the higher EGR levels required in 2010.
“Is the heat load going up? The answer to that is yes, just like it has gone up the past 20 years as we’ve added air-conditioning, bigger alternators and all the things we’ve added to trucks that increase the load on the engine,” Shick explained. “(But) the engines themselves will not run hotter than they do today, they’ll just require bigger cooling systems.”
International trucks will come with larger rads in 2010, and heat-sensitive components such as EGR valves will be wrapped in a water jacket, Shick said.
He dismissed concerns that increasing EGR levels may cause piston or cylinder wear.
“People say ‘Don’t put the exhaust back in the cylinder.’ Well, that’s where it came from, it’s not going to damage the cylinder.”
He likened the warning to advising someone not to swallow saliva, which is produced in the mouth to begin with.
Shick also challenged the cost-savings being touted by the SCR camp, which has promised its engines will achieve 3-5% better fuel economy. The rising cost of diesel was one of Cummins main motivators behind switching paths earlier this summer.
Shick admitted engines with SCR may consume less diesel, but he said “For every gallon of diesel fuel you don’t use through more aggressive tuning of that engine, you’re going to have to add a gallon of urea to render down the NOx.”
He said both 2010 options will use the same amount of fluid going down the highway, but “the challenge is, how much is urea going to cost?”
“Those who offer SCR are pretty consistent in their expectations of 2-3% fuel economy improvement. For every 100 gallons diesel fuel consumed by a pre-2010 engine, they say the 2010 SCR engine will consume only 97 gallons or 98 gallons of diesel fuel due to more aggressive engine tuning,” Shick explained.
“Our work shows that the resulting higher level of engine-out NOx with this scenario would require two to three gallons of urea to neutralize. Plus another gallon of urea is needed at base to improve the pre-2010 engine to 2010 emission levels with no improvement in fuel economy. So you have a total 2010 requirement of three to four gallons of urea to save two to three gallons of diesel fuel.”
Whether or not SCR-equipped engines will deliver lower cost of operation depends on whether or not the cost of urea will be less than diesel, Shick insisted.
Allen added urea costs as much as $12/gallon in parts of Germany, not taking into account volume discounts.
SCR proponents have insisted urea will cost less than diesel when rolled out across North America.
As far as the purchase price of 2010 vehicles is concerned, Shick said it’s too early to determine, as the company is still working with suppliers to finalize pricing of the necessary components.
But when it comes to cost of operation, he said “To operate a truck with EGR for a year we think is going to be less expensive than SCR.”