Tenneco Inc. recently unveiled two new diesel emissions-control systems aimed at OEM applications in the 2012-14 time frame. The new technologies are part of the company's growing portfolio of aftertreatment solutions designed to meet EPA Tier 4 on- and off-highway diesel engines.
"We're launching programs with 11 commercial vehicle customers through 2011," said Brent Bauer, Senior Vice President/General Manager of Tenneco's North American Original Equipment Emission Control, during a June media briefing at the company's North America Emission Control Research and Development Center in Grass Lake, MI.
The two new technologies are HC-LNC (a silver-based Hydrocarbon Lean NOx Catalyst) and Solid SCR. The HC-LNC could be available for production as early as January 2012. The new systems join Tenneco's current range of urea-based Selective Catalytic Reduction (SCR), NOx Absorber, and Exhaust Gas Recirculation (EGR) aftertreatment systems.
A key material in the HC-LNC system is a proprietary silver-based catalyst with an engineered nanostructure, developed at GE's Global Research center in 2001.
"Using this catalyst with E85 as the reductant, researchers demonstrated high NOx conversions across a range of temperatures along with improved resistance to thermal aging," Bill Kernick, GE's Vice President of Technology Ventures, told AEI.
He said the E85 (85% ethanol/15% gasoline) reductant enables vehicles equipped with the HC-LNC system to use existing infrastructure for replenishment. E85 provides "an alternative to urea-based systems, which carry concerns including shelf life, freeze/thaw, and corrosion that are not seen in the HC-LNC solution," noted Kernick.
Tenneco is the systems integrator for the HC-LNC. Its hardware components include a diesel particulate filter, a vaporizer, dosing system, Tenneco's T.R.U.E.-Clean combustion-sensing technology, and an injector.
According to Tim Jackson, Tenneco's Chief Technology Officer, "All of the metals and all of the seals inside the injector are compatible with diesel fuel, urea, as well as E85 ethanol."
HC-LNC's diesel fuel vaporizer functions similar to a diesel glow plug.
"It heats up with electricity and once the diesel fuel reaches atmospheric pressure, it goes straight to vapor instantly. That's important because we don't want the diesel fuel to burn before it reaches the face of the catalyst," said Jackson.
The dosing system includes the sensors and pumps for delivering E85 and diesel fuel to the aftertreatment.
Instead of a diesel oxidation converter (DOC), HC-LNC uses T.R.U.E-Clean (Thermal Regeneration Unit for Exhaust), co-developed with the Woodward Governor Company based in Fort Collins, CO.
"T.R.U.E.-Clean is a combustion-sensing technology that continually monitors the diesel particular filter's temperature and soot levels," Jackson explained. "The aftertreatment control unit automatically initiates the regeneration process when it senses the filter needs cleaning. And because T.R.U.E.-Clean responds to throttle transients quickly and minimizes unburned hydrocarbons, HC-LNC doesn't use a DOC."
Belgium-based Umicore is responsible for all production aspects of HC-LNC's powder and catalyst, including the work being done currently for small-scale pilot production.
"On a very accelerated timeline, HC-LNC could be ready for a January 2012 launch. On a more relaxed timeline, it will be available to support 2013 midcycle refreshes for manufacturers or to meet the requirements of the EPA's Tier 4 final in 2014," said Jackson.
Solid SCR, which Tenneco is co-developing with FEV, also is close to being production-ready.
"In the Solid SCR process, a heat transfer fluid is sprayed onto a brick of ammonium carbamate, and it goes straight from solid to gaseous form," Jackson explained. "The carbamate sublimates into ammonia and CO2 and both gases are injected into the exhaust system. Any ammonia left over recondenses back into the solid block."
In contrast, the Urea SCR process necessitates first vaporizing liquid urea to gas and then going through a thermolysis reaction that decomposes the urea into ammonia. That process takes temperature and time, noted Jackson, adding "one of the advantages of a Solid SCR system is functionality at very low temperatures."
Both the HC-LNC and the Solid SCR technologies can be applied to any diesel engine. "Tenneco is developing these technologies for current customers in a wide range of diesel engines ranging from 28 hp all the way to 6000 hp (21 to 4474 kW)," Jackson said.