LOUISVILLE, Ky. — Caterpillar officials went on the offesive at the Mid-America Trucking Show, promising their ACERT technology is the best solution for 2007 emissions standards and warning “a day of reckoning is coming” for EGR.
Jim McReynolds, general manager, Caterpillar Power Systems North America, warned “There’s a huge storm cloud over EGR engines,” adding Cat’s own testing has proven increased EGR will result in soot build-up that will deteriorate fuel economy and shorten engine life.
Caterpillar is continuing to forge ahead with its ACERT technology in 2007, but it will add a new process called Clean Gas Induction (CGI) to meet the new standards. It will also use a diesel particulate filter, much like other manufacturers.
CGI involves drawing off a small amount of non-combustible gas after it passes through the DPF. The gas is then cooled, blended with more incoming, cool, clean air and then returned to the combustion chamber, explained Greg Gauger, director of Caterpillar On-Highway Power Systems.
If it sounds a lot like EGR, that’s because in essence, it is, admitted Gauger.
“Is CGI actually EGR? The answer is yes. It’s simply not dirty EGR,” he said.
Caterpillar officials insisted using unfiltered exhaust will result in substantial soot accumulation in the engines, which would in turn impact fuel economy and engine life expectancy.
“Rather than re-introducing ditry, sooty exhaust back into the system, CGI uses more cool, clean air to reduce combustion temperatures and achieve the necessary reduction in NOx and particulate matter,” Gauger explained.
He added CGI will allow Caterpillar engines to maintain current fuel economy levels (with mid-range engines realizing a four per cent fuel mileage improvement thanks to an improved common rail fuel system). Service intervals will also remain the same as today, Gauger insisted.
In terms of the DPF, Caterpillar’s system will differ from those of competitors by utilizing a regeneration process that’s similar to a gas-fired furnace. In order to ensure regeneration can occur under any condition, Caterpillar developed its Cat Regeneration System (CRS), which introduces fuel into a closed combustion chamber rather than the DPF itself. Officials say the system uses the precise amount of fuel required to heat and oxidize the soot.
“We wanted a product that would be able to regenerate under all conditions,” explained Gauger. “We designed a process to allow our product to accomplish this safely, without the risks created by dosing.”
Caterpillar engines with more than 550 hp will require two smaller DPFs to get the job done.
Caterpillar officials introduced the results of some recent studies at the Mid-America Trucking Show, which they say prove ACERT is a better solution for 2007 than EGR.
One such test compared a Cat C15 to a Cummins ISX. Conducted over a two-day test run from Denver to San Antonio, Caterpillar officials said the Cat engine delivered a 5.8 per cent improvement in fuel economy. Two additional SAE Type III (J1526)-approved tests found the Cat engines showed a 3.2 and 3.8 per cent better fuel mileage, said Gauger.
“These were single unit tests with identical specifications and conditions. The results were verified by the independent consultant who ran the tests,” he added. “It validates what customers have been telling us all along – when you spec’ them right and drive them right, Cat engines with ACERT technology get the best fuel economy.”
To defend claims that ACERT will be a better 2007 emissions solution than EGR, Caterpillar officials also shared the results of a test they say proves their case. Caterpillar recently sponsored the disassembly and analytical comparison of three engines from three different manufacturers, including Caterpillar.
A C15, Cummins ISX and Detroit Diesel Series 60 – all with comparable horsepower ratings and mileage – were inspected as part of the test. Caterpillar officials pointed out the analysis showed the EGR engines (which had 361,000 and 381,000 miles on them respectively) had a significant accumulation of soot along the inlet manifolds and in the engine oil. The Cat, meanwhile, had no soot accumulation in the inlet manifold and lower soot levels in the oil, Gauger said.
“The difference between cooled EGR and Caterpillar ACERT technology is simple – Cat uses more cool, clean air to lower the combustion temperature, instead of recycling raw unfiltered exhaust,” Gauger said. “Cooled EGR is another method to reduce oxides of nitrogen, but it also causes soot to accumulate on the engine components, which can result in premature wear. Our recent engine disassembly and analysis convinced us that Cat engines have an advantage in this area, since there’s less soot accumulation.”
Caterpillar’s Steve Brown added the company is already prepared for 2007. He said there are more than 100 units undergoing customer field testing and Cat has already racked up three million miles on the ’07 engines. While Caterpillar officials didn’t directly address pricing, they did confirm customers will continue to pay a premium for Cat engines compared to competitive products.
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