The number of 2010 EPA emission-compliant heavy duty on-highway diesel engines in use has been gradually increasing. “The slower uptake of the 2010 and now 2011 engines has been more a function of lack of confidence in the economy than lack of confidence in the technology,” says Allen Schaeffer, executive director of the Diesel Technology Forum, an organization dedicated to raising awareness about the economic importance of diesel engines.
“The March freight tonnage index is up over 6 percent according to the American Trucking Associations, and recently, ACT research reported that Class 8 truck orders are now up more than 25,000 units for five consecutive months,” he says. “That would put us on a yearly pace of well over 200,000 units - a very strong sign of recovery and a confidence in the technology.”
With the economy on the uptick and fuel prices at $4 per gallon-plus, fuel efficiency is more important than ever before. Truck orders are up in large part due to the benefits of the new engine technology in saving fuel, says Schaeffer. “Everyone is pretty consistently saying they are getting 5 percent gain in fuel economy.”
SATISFIED USERS
In general, customer acceptance and satisfaction of the 2010 EPA engines is quite high. Truck owners and users have been “very satisfied,” and in many cases the results have exceeded their expectations for performance and power, and they have experienced fuel economy surpassing 2007 engine levels.
“We know the diesel engine still has a few tricks left up its sleeve in getting more efficiency out, and that is expected to be in round one of the final greenhouse gas emissions rule,” the Diesel Technology Forum’s Schaeffer says. “The later aspects of the rule will likely push more into vehicle integration and vehicle issues than engine issues.”
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DRIVING DIFFERENCES
For drivers, “it is a matter of awareness and education” with the 2010 EPA engines, says Kurt Freitag, director of aftermarket for Paccar, which manufactures Kenworth and Peterbilt trucks. These engines are “significantly different in how they run compared to previous engines.” Because the engines are quieter, the driver feels different sensations - less vibrations, no turbo noise, no rumbling, etc.
A driver that is used to hearing turbo noise or feeling the way a vehicle vibrates as an indication to shift won’t have that with the new engines, he says.
ENGINE SALES
From January 1, 2010, through end of March 2011, Cummins has built and shipped more 89,100 EPA 2010 engines, says the company’s Christy Nycz, manager of on-highway communications. More than 25,000 of that volume include ISX15 and ISX11.9 engines.
Paccar began installing its 2010 emissions-compliant MX diesel engines in Kenworth and Peterbilt trucks for the U.S and Canada last June, says Paccar’s Freitag. “Currently we have thousands in service and demand is up.”
“Since the start of the commercial launch in September 2009 of our fully certified EPA 2010 Mack ClearTech engines, demand has been strong, even in light of the mountain of stockpiled competitor pre-2010 engines,” David McKenna, Mack Trucks’ director of powertrain sales and marketing, says.
Ed Saxman, product manager - powertrain, for Volvo Trucks North America, says: “Since we started filling customer orders for actual production units in the fall of 2009, more than 1,000 customers across all market segments in the U.S. and Canada have purchased trucks with Volvo’s EPA 2010 solution. Demand continues to grow and we continue to see a very strong re-order rate.”
“Detroit Diesel Corporation has produced or sold approximately 65,000 EPA 2010 engines since January 1, 2010, and has delivered more than 30,000 of them to customers,” says Brad Williamson, manager of engine and component marketing for Daimler Trucks North America. Detroit Diesel is an affiliate of Daimler Trucks.
Tim Shick, director of marketing, for the Navistar Engine Group, says about 40,000 Advanced EGR 2010 engines have been produced, including 12,000 MaxxForce 13 and 18,000 MaxxForce DT engines, with the balance lower volume engines.
MAINTENANCE ISSUES
None of the manufacturers have found any significant engine issues or problems. A few reported some minor controls and calibration issues with the very earliest of engine deliveries but these were quickly resolved.
“The only real issue we’ve experienced is the collection of empirical data on engine performance because we’ve had so few problems,” says Mack Trucks’ McKenna. “We actually have to ask our dealers and customers to upload logged vehicle data for analysis in support of, and validation of, our performance predictions.”
“Measured by reported faults, this has been Volvo Trucks’ most successful engine introduction,” notes Saxman of Volvo Trucks. “Much of our success can be attributed to our No Regen strategy, which uses only NOx (nitrogen oxide) for passive regeneration of soot from the diesel particulate filter. Because we’re not using fuel to regenerate soot, temperatures are much lower.
“Our most ‘senior’ EPA ‘10 engine now has well over 300,000 miles in all sorts of conditions and we’ve had no problems.”
DEF MATTERS
EGR (exhaust gas recirculation) is an emissions reduction technique that works by re-circulating a portion of an engine’s exhaust back to the engine cylinders and burning off excess pollutants. Navistar is the only engine manufacturer to use EGR to meet 2010 diesel engine emission regulations.
The other manufacturers use selective catalytic reduction (SCR). SCR uses a urea-based diesel exhaust fluid (DEF). Small quantities of DEF are injected into the exhaust upstream of a catalyst, where it vaporizes and decomposes to form ammonia and carbon dioxide.
“We’ve been pleasantly surprised about the lack of issues relative to the DEF systems,” says Schaeffer of the Diesel Technology Forum. “As far as we know, there are not any supply issues with DEF or its availability in the first full year of use, and that’s pretty impressive going from none anywhere to adequate supply in about three years.”
Problems with diesel exhaust fluid systems have been a non-issue since early 2010, adds Williamson of Daimler Trucks North America. The industry as a whole stepped up and answered the call for a DEF infrastructure. “There are over 3,500 locations across North America where drivers and fleets can purchase diesel exhaust fluid.”
Adds McKenna of Mack Trucks: “The introduction of DEF has gone smoothly and is widely available at affordable prices.”
DPF SYSTEMS
All of the engine manufacturers say they have been very pleased with performance of their aftertreament systems and have not had any noteworthy issues. Each stressed the importance of having the system’s diesel particulate filter (DPF) serviced at regular intervals. “A dirty DPF still ‘breathes,’” says Saxman of Volvo Trucks, “but it’s more effective if kept clean.”
Both EGR and SCR emissions technologies utilize DPF technology to decrease particulate matter (soot) emissions.
Paccar’s Freitag says many of the issues with aftertreatment systems can be traced to drivers not understanding the DPF status lights for regeneration activities.
DPF TECHNOLOGY
Basically, DPF technology works by employing a honeycomb ceramic structure with a series of alternate channels plugged at opposite ends. The diesel exhaust gas is forced through the open end of each channel.
The plug forces the soot particles against the porous channel cell walls to burn off there and allow only gases like steam and carbon dioxide (CO2) to pass through to the neighboring exit channel.
Highway driving and high engine load results in lower accumulations of particulate matter (PM) and high exhaust temperatures. A lot of idling and low speed/low engine load creates more PM, causing soot to build up in the DPF. Successful thermal regeneration clears the DPF of all the soot.
There are two types of thermal regeneration: passive and active. Passive regeneration happens automatically during vehicle operation when the heat of the exhaust burns off the soot.
Active regeneration becomes necessary when the temperature is too low to completely burn off the soot. The process is initiated by injecting fuel into the exhaust automatically, with no driver interaction needed.
However, if soot continues to accumulate in the DPF, a parked regeneration is required. The driver is alerted to this through the DPF indicator lamps on the instrument panel. He must park the vehicle and initiate the regeneration process by pushing a button on the dash or holding the accelerator at a high idle rpm for up to 30 minutes.
LIFE EXTENTION
Although the DPF is designed for long life, to ensure that an optimum level of performance is maintained, the filter must be cleaned at regular intervals. This is necessary as small amounts of inert debris, mainly accumulated mineral and metal particulate from lubricating oil and engine wear, build up in the filter substrate. This inert, unburnable material is known collectively as ash.
Ash builds up and occupies space in the cells intended for soot. However, unlike soot, ash does not burn off. It must be physically removed from the DPF.
Typically, most engine OEMs recommend this be done between approximately 200,000 to 250,000 miles for less severe service applications, such as Class 8 linehaul operations.
FILTER ISSUES
Some fleets think that by ignoring ash buildup in their DPF they can avoid another operating expense. Besides, if the DPF fails under warranty it is covered.
Other fleets have discovered that by allowing the DPF to fill up with ash it will eventually crack and rot out to the point that the ceramic material breaks up, crumbles and blows out the exhaust stack. Provided the truck has not been forced to the side of the road with backpressure warnings, the ceramic core can partially or totally disappear.
This sudden loss of backpressure will result in a slight improvement in engine performance and mileage.
One problem comes when the truck is resold and a new replacement DPF must be installed costing several thousand dollars.
Since the primary function of a DPF is to eliminate soot from diesel exhaust prior to escaping to the atmosphere, the DPF is vital to helping prevent serious air pollution, says Drew Taylor, national sales manager for FSX Equipment, a company that provides filter cleaning systems and services for cleaning diesel particulate filters.
He says a good rule of thumb is: If you observe soot (black) in the exhaust stack/pipe or observe heavy black smoke coming from a truck’s stacks, this is a sure sign the DPF is not working and harmful pollutants are being emitted into the atmosphere.
COMMON MYTH
Since 2007, to meet EPA heavy duty diesel engine emission requirements, vehicles now come standard with aftertreatment system warning lights and indicator symbols. These alert the operator to actions being taken or to actions that need to be taken.
“One of the most common DPF myths circulating is that the DPF status light indicates when the DPF needs to be cleaned of ash,” says Taylor. “That is false. This light keeps the driver informed about the active regeneration system as it periodically clears out soot buildup to relieve backpressure created by soot.
“By the time the DPF status light shows signs of ash buildup in a DPF, the condition is so far advanced that substrate cracking and other damage are well under way,” he points out. “The only way the driver can see this is by noticing the regenerations are occurring one after another as the sensors detect DPF backpressure that does not respond to thermal regeneration.”
This is why ash removal must be done proactively as a scheduled maintenance item, stresses Taylor. The best DPF rule of thumb: Take it off and clean it sooner than later.
“If you leave ash in the DPF too long it becomes like a cancer that grows in the filter over time,” he says. “If left in place, the ash becomes hardened, making removal even more difficult. The solution is to get the ash out before it has the time to solidify.
“Because the ash is cooler than the surrounding material, it causes cracking of the brittle ceramic. Once the cracking starts, it is irreversible damage that will continue to worsen and eventually destroy the filter.”
SNIFF TEST
In the near future, opacity testing - commonly referred to as the sniff test - will become more commonplace to detect emissions cheaters.
In an effort to control excessive smoke emissions, California already requires annual smoke inspections for heavy duty vehicles, notes Taylor of FSX Equipment. This is through the California Air Resource Board’s Periodic Smoke Inspection Program (PSIP).
The PSIP requires diesel and bus fleet owners to conduct annual smoke opacity inspections of their vehicles, and repair those with excessive smoke emissions to ensure compliance.
A fleet owner that neglects to perform the annual smoke opacity inspection is subject to a penalty of $500 per vehicle, per year. The penalties for excessive smoke range from a fix-it ticket to a $1,800 citation, and the California Highway Patrol can take the vehicle out of service.
Basically, a smoke test is a simple, brief test performed on a vehicle when it is standing still and in neutral. The engine is accelerated while a smoke meter is placed at the end of the exhaust pipe and the opacity of the smoke is measured.
The opacity, expressed as a percentage of light reduction, is the degree to which the exhaust obscures a beam of light shining through it.
A number of other states have laws that require heavy duty vehicles to submit to random roadside diesel opacity testing when requested by the appropriate authority. It is anticipated that the U.S. EPA will soon consider legislation aimed at increasing such programs.
Diesel emissions technology types
To comply with the EPA 2010 diesel emissions standards, engine manufacturers settled on two types of emissions control technologies: selective catalytic reduction (SCR) and exhaust gas recirculation (EGR).
SCR allows the engine to be optimized for fuel efficiency and treats the engine exhaust downstream. EGR, also referred to as in-cylinder EGR and enhanced, advanced or massive EGR, reduces emissions in the engine cylinder.
Both EGR and SCR technologies reduce oxides of nitrogen (NOx) emissions. To decrease particulate matter (PM) emissions, both systems employ diesel particulate filter (DPF) technology to trap and remove PM from diesel exhaust.
Navistar International, with its MaxxForce engines for its International brand trucks, is the only heavy duty truck company to offer an EGR solution at this time.
All others, including Daimler Trucks North America, Mack Trucks, Paccar and Volvo Trucks North America, plus engine maker Cummins, use SCR technology.?
Diesel exhaust fluid: supply vs. demand
As fleets began purchasing their first trucks equipped with selective catalytic reduction (SCR) technology to comply with the EPA’s “Heavy Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements,” which began to take effect in model year 2007, they were asking questions such as “Where will I get the diesel exhaust fluid (DEF) these vehicles require?” and “Will there be enough DEF available for my fleet?”
SCR uses a solution called diesel exhaust fluid (DEF) that is sprayed into the exhaust and combines with a catalyst to break down NOx pollutants into nitrogen and water.
“By drawing on our experiences from Europe, where this market was pioneered in 2005, and realizing how the unique needs of the U.S. market are being addressed, fleets don’t have to worry about DEF availability,” says Chad Dombroski, director of Air1 for Yara North America.
Yara is the world’s largest DEF producer. Air1 is Yara’s DEF brand around the world.
The U.S. DEF market is expanding much faster than the European market did when it began, he says.
UREA SOURCES
Although the supply of domestic urea required to produce DEF, fertilizer and other products is plentiful, there’s been some concern that agricultural and geographical demand spikes for urea could cause supply chain stress, notes Dombroski.
“Given the scale and growth potential of the U.S. market, supplementing domestic production with international production will be an integral safeguard,” he says. “The most diversified and reliable model for supplying DEF domestically is a multi-sourcing approach which leverages a mix of local production and imports, to mitigate risk so that no single failure causes a shortage.
“Multi-sourcing allows producers to meet demand even if unpredictable events occur at one site of production similar to what happened in Japan or North Africa.”
SUPPLY CHAIN
Another daunting challenge is ensuring that even with enough supply for the U.S. market, DEF is easily accessible for trucks on the road, no matter where they travel.
To ensure DEF gets to where it is needed, Yara, by way of example, uses best supply-chain practices from Europe.
“The most effective strategy for distributing DEF is to work with a distributor who has an extensive national network and can leverage existing delivery synergies,” says Dombroski. “While the type of distributor with these capabilities varies by market, using a fuel and lubricant distributor unequivocally makes the most sense from a supply chain standpoint in the U.S.
“Why reinvent the wheel? U.S. fuel and lubricant distributors such as Mansfield Oil, who we have partnered with in the U.S., have well established relationships with the nation’s largest fuel stations and the delivery network in place to support mass DEF distribution.”
SOLID SUPPLY
The model is working, say Dombroski, as supply continues to meet demand as the production and distribution of DEF grows steadily with the U.S. market.
“DEF is widely available throughout the country,” he says. “The retail network has grown, with more than 3,000 locations selling packaged DEF today, and the supporting infrastructure is steadily expanding as the nation’s largest truck stops continue to install DEF pumps to serve their customers.”
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How to get the most out of a DPF
While some truck users have had issues with the life of diesel particulate filters (DPF), owner operator Grant Sheldon, G.E. Sheldon Trucking, Henderson, KY, has logged more than 500,000 miles on his before having it cleaned.
Sheldon hauls automotive parts throughout the U.S. with his 2008 Kenworth T660 tractor. It is spec’d with a 485-horsepower, 1,850 pound-feet of torque Cummins ISX diesel engine, 18-speed Eaton transmission and 3.25 ratio rear axles. It is coupled to a 2008 Wabash 53-foot van trailer. Both tractor and trailer have Michelin XDA3 tires all around.
Proudly calling himself a “fanatic” when it comes to vehicle maintenance, Sheldon pays meticulous attention to the smallest details. He attributes the long life of his Cummins diesel particulate filter to several things:
- Extremely low idle time through the use of an APU.
- Using a Fleetguard Bypass Filter, maintaining engine oil at the “Full” mark and completing an oil change every 18,000 miles with an oil analysis to monitor engine condition.
- Using only Cummins-approved engine oil and fuel additives.
- Having all engine work done at Cummins Crosspoint, a Cummins Dealer, and having every engine update done as soon as possible. Having a long-time established relationship with a dealer, it alerts Sheldon to each new update.
- Gearing his Kenworth to run 1,220 rpm at 65 mph. “The lower the engine rpm, the less fuel used by the engine and the less exhaust through the DPF,” says Sheldon.
At 500,000 miles, he took his DPF to Cummins Crosspoint to have it cleaned using the dealer’s Air Knife technology pneumatic cleaning process. The technicians, surprised by the cleanliness of the DPF, asked Sheldon how he did it.
“It’s all about effective maintenance,” Sheldon, a successful owner operator since his start in 1970, told them. “Good maintenance, done on a regular schedule, ensures long vehicle life and vehicle reliability, with minimum problems on the road and outstanding resale value.
“It takes a lot of time and effort to custom tailor a preventive maintenance for your equipment and operation,” he says. “But it has been my experience that the return on investment, in terms of operational efficiencies and bottom line contributions, is well worth it.
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What exactly is DEF?
Diesel exhaust fluid is a necessary ingredient for selective catalytic reduction (SCR) technology to reduce nitrogen oxide (NOx) emissions from diesel engines. When DEF is injected into the engine exhaust gas downstream of the DPF (diesel particulate filter), it will be rapidly hydrolyzed, producing the oxidizing ammonia needed by the SCR catalyst to complete NOx emissions reductions.
DEF is a chemical solution comprised of 32.5 percent automotive grade urea and 67.5 percent de-ionized water, explains Dave Michael, general manager of DEF for Mansfield Oil Company. Urea is a naturally occurring compound made up of ammonia and carbon dioxide.
Mansfield Oil provides comprehensive fuel supply, distribution, delivery and dispensing solutions to customers through an integrated network of refiners, terminals, carriers and retailers throughout North America and Canada.
“Once a DEF brand is certified by the API (American Petroleum Institute), then those brands are chemically the same,” he says. “There are no superior/inferior chemical properties between brands as DEF must meet stringent ISO 22241 specifications.
“Brands that do not have an API ‘stamp’ or approval are the ones to stay away from. There are many out there that believe that so long as you have urea prills (pellets) and some water that they can also manufacture DEF. These folks will run into some serious problems with SCR unit failures, especially if fertilizer grade urea is used.”
WEATHER CONDITIONS
DEF will freeze at approximately 13 degrees Fahrenheit, but it can freeze and thaw time and time again without affecting its chemical properties, notes Michael. “The OEMs have installed heating mechanisms around both the DEF reservoir and corresponding lines to ensure that the DEF will be thawed into a liquid state for proper use.
“DEF is only affected by high heat temperatures if exposed to constant 85 degrees or higher heat for long periods of time. There is debate on how long of a timeframe, but we like to use 6 months. It will be very rare to experience these types of conditions outside of Arizona.”
The most damaging form of weather to DEF is actually sunlight (UV rays), he points out. Customers storing their DEF outdoors need to keep it in shaded areas.
“Sunlight does not immediately damage DEF, but just like most things where if exposed for very long periods of time, it will begin to break down. Most customers will use their product far too quickly to ever be concerned about UV damage.”
FLIUD MIXING
If a non-DEF substance is accidentally entered into the DEF tank, the tank should be immediately drained, flushed with DEF, then drained again, advises Michael. SCR units and components are far too costly (estimated $10,000) to take a risk and poison the system’s catalyst.
“Most contamination will not shut the truck down immediately, but will instead wear and tear on its componentry over time,” he says. It is very important for customers to understand and educate their drivers as off spec DEF from a non-API approved vendor will not show much damage until it is too late.”
DEF CONSUMPTION
OEMs estimate that DEF consumption will average around 2 to 3 percent of corresponding diesel fuel consumption. The rate of injection will vary by application.
“Trucks are designed to calibrate exactly how much NOx is being spewed out of the exhaust in correlation with rpms and will communicate to the DEF dosing module as to how much DEF should be sprayed into the exhaust stream to mitigate that NOx,” explains Michael.
As the vehicle begins to get low on DEF volume a series of indicators will flash on the units cluster. “If the driver disregards those messages and runs out of DEF, the truck will begin to gradually derate or lose power,” he says. “If the driver still continues, eventually his truck will be slowed down to an idle.
“Once the key of that vehicle is turned off, the driver will need to fill the reservoir with at least two gallons of DEF to start the unit back up.”
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