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Government Issues
Diesel Particulate Filter Meets CARB Standards
By Sherri Middleton
When California adopted rules for operating auxiliary power units (APUs) in the Golden State, OEMs, fleets and owner/operators were worried that they could not meet the Jan. 1, 2008 compliance date.
A few companies have met the challenge.
Carrier Transicold’s ClearSky diesel particulate filter (DPF) joins the list of units approved or conditionally verified by the California Air Resources Board (CARB).
Cummins, Rigmaster and others also recently announced DPF-compliant APUs.
Verification of the filter allows operators of Class 8 tractors with 2007 or newer engines to use APUs with DPF in California to reduce the environmental effects of idling.
Pre-2007 truck and smaller engines remain legal to use, but the engine time is limited to the five-minute rule without the DPF.
Most 2007 compliant engines feature two types of regeneration.
• Passive Regeneration – occurs automatically when exhaust gases are hot enough during vehicle operation at highway or operating speeds to burn off accumulated diesel soot. This happens without driver interaction.
• Active Regeneration – occurs when enough soot accumulates in the filter to raise exhaust backpressure. Fuel is injected into the exhaust automatically without driver action.
Using highly efficient active regeneration technology, the ClearSky DPF achieves CARB’s APU emission standard. The CARB rule calls for particulate matter to be reduced by 85 percent. Nitrogen Oxide (NOx) is also reduced to meet CARB emission regulations.
“The rules have had a great deal of impact on long-haul customers because almost all long-haul fleets have some level of contact with California.” Says Eduardo Andrade, director of business development for Carrier Transicold. “There has been a great deal of impact also because of uncertainty about how they will meet the challenge and be compliant.”
Andrade and other experts around the country who deal with diesel emissions issues say CARB was “pushing the envelop of what was possible” with the available technology in 2005 when the decision was made to create strict regulations regarding diesel engine emissions.
“When these discussions started there were no devices that dealt with particulate matter, and there was uncertainty about enforcement,” he says. “Now products are verified and there is more clarity and understanding about regulations.”
Andrade adds that active regeneration technology presents unique advantages, but he says it has been a challenge for most APU manufacturers because the units typically don’t generate enough heat to burn off particulates from the exhaust.
“The challenge for us (Carrier) and others like us, was refining the available technology; designing and testing new equipment; implementing quality controls and field testing to verify our results,” he said. “It was a consuming effort and a challenge for vendors as well, because not every manufacturer has the major financial resources to develop new technology in such a short period of time.”
New Technology
While researching and developing the new technology for DPF filters for APUs was challenging, Andrade says the ComfortPro APU Deltek hybrid diesel-electric technology is unique, and the generator is strong enough to create the necessary temperatures to meet the high standards for CARB and the Environmental Protection Agency (EPA) rules.
Diesel particulate filters like Carrier’s ClearSky filter is designed to capture soot and prevent particulate matter from leaving the APU. The soot instead accumulates in the filter where it is incinerated with high heat during active regeneration.
“Some devices use passive filters that produce chemical reactions to eliminate soot,” he said. “We didn’t find this was good for us because of the high temperatures on a regular basis in the unit. We chose active technology that raises the temperature regularly. Every so many hours we divert energy to the filter to burn soot.”
The advantage is the APU needs fewer parts and the self-regeneration happens only when needed. The driver doesn’t have to remember to perform maintenance at regular intervals.
With a silicon carbide filter element and an easy-to-maintain design, the ClearSky DPF replaces the ComfortPro muffler on new equipment, and it can be field installed on existing units (model PC6000). The driver doesn’t have to remember to burn off the soot. The ClearSky DPF automatically regenerates in less than 25 minutes for every 10 to 30 operating hours.
Without a DPF, some truckers are prohibited from running their diesel-powered APUs in California. The law applies to trucks equipped with 2007 or newer engines and rigs with older engines may still use ComfortPro with the new DPF.
Newer rigs can also take advantage of the new technology by connecting to shore power when parked where there is a 110-volt power supply. This allows drivers to maintain cab and sleeper comfort levels even after the five-minute rule because of the new DPF technology.
“Our filter is mounted behind the APU like a muffler, but it is self-contained and connects directly to the truck’s fuel line,” Andrade said. “It’s out of the way, but it provides fuel savings and provides the benefits of APUs without the negatives.”
For more information on ClearSky or ComfortPro, visit www. Carrier Transicold at www.trucktrailer.com.
Fast Facts on DPF
A diesel Particulate Matter Filter (DPF) is a ceramic device that collects particulate matter in the exhaust system.
The fine particles in diesel exhaust known as particulate matter can penetrate deep in the lungs and pose serious health risks.
Heavy-duty trucks account for one-third of NOx emissions and one-quarter of PM emissions.
Follow manufacturer recommendations on cleaning or replacing filters. Some particulate matter does not oxidize and ash remains in the filter. |
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