Note from the Director
ORNL's Fuels, Engines, and Emissions Research Center (FEERC), located at the NTRC site, conducted R&D for multiple subprograms of the Office of FreedomCAR and Vehicle Technologies (OFCVT) in 2005, including Advanced Combustion Engines, Fuels Utilization, Vehicle Systems, and Health Impacts. Strong industry collaboration in FEERC was evidenced by five CRADAs in engine/emissions technology, plus less-formal, yet very active collaborations with approximately 15 additional private companies and non-DOE agencies. Some of the CRADAs have resulted in unique research hardware being installed at FEERC. In addition to the CRADAs, six private-sector firms sponsored R&D at the Center in FY 2005. FEERC held its third Research Guidance Panel meeting in November 2004, with members from Ford, Cummins, BP-Amoco, Caterpillar, Umicore, and others.
FEERC staff are highly engaged in supporting FreedomCAR and 21st Century Truck Partnership (21CTP) programmatic activities such the Advanced Combustion and Emission Control tech team, the Diesel Crosscut Team, and the 21CTP “Lab Council”. ORNL provides co-leadership with industry of the Cross-cut Lean Exhaust Emissions Reduction Simulation (CLEERS) activity. In fuels utilization, FEERC staff co-chaired three subteams of the Advanced Petroleum Based Fuels-Diesel Emission Control project and sit on the steering committee in partnership with NREL. FEERC staff also participate on working groups for the Coordinating Research Council. Our facilities and staff are significant participants in the Advanced Reciprocating Engine Systems (ARES) projects in the Distributed Energy Program. Both OFCVT and ARES benefit from this leveraging.
There were a number of additions to capabilities at FEERC in FY 2005 in order to stay current with the challenges and research requirements of our partners and DOE. Some of these are listed here:
- Variable compression ratio engine transferred to ORNL by DOE
- Hydrogen fuel capability added for engine and NOx aftertreatment studies
- Engine and combustion simulation models
- Electrospray and negative chemical ion mass spectrometry
Advanced Combustion Engines research is undergoing an orderly shift to more emphasis on improving engine fuel economy through advanced combustion regimes and other technologies, while retaining critical projects on key remaining issues in emission controls. ORNL participates with fourteen other organizations in a Memorandum of Understanding (MOU) on Advanced Engine Combustion Research. Our specific roles in the MOU are: (1) determine how advanced combustion regimes might be exploited for inherent efficiency gains, (2) determining the detailed emissions species generated by these combustion regimes, and (3) researching control strategies for full power density and transitions. Powerful capabilities in engine electronic control prototyping were exercised to show quick and near-seamless transitions between operating points within the low-temperature combustion (LTC) operating space.
Although most LTC emphasis has been based on diesel-fuel, gasoline-based homogeneous charge compression ignition (HCCI) engines can potentially yield higher efficiency than conventional spark-ignition engines and can also reduce emissions. ORNL has been studying the use of spark augmentation for stabilizing the cycle-to-cycle efficiency variation encountered in certain types of mixed-mode (conventional and HCCI) engines. This research has found that the cyclic dispersion encountered during the conventional-to-HCCI operation transition is complex (high period or deterministic chaos with noise) but is short-time predictable. This indicates that it may be possible to develop pro-active control algorithms for stabilizing HCCI and for these transitions, helping expand the overall operating range.
Research on improving the efficiency of lean NOx trap (LNT) regeneration led to a new strategy that integrated the features (low NOx and high HC) of LTC with mild fuel enrichment to de-NOx the LNT. The technique provides 5-10 times the NOx reduction per unit of excess fuel.
An engine management strategy was identified that can produce moderate levels of hydrogen in the engine exhaust in overall lean operation that would enhance the performance of lean-NOx catalysts. The experiments to confirm this were requested by an automobile OEM.
The CLEERS (Cross-cut Lean Exhaust Emissions Reduction Simulation) team continued development and validation of a standard protocol for LNTs. The success of the LNT collaboration has provided a framework for similar data sharing and collaborations among Crosscut Team members for urea-SCR and diesel particle filter technologies. The team aslo maintained the website and organized the eighth CLEERS workshop.
An extensive study of fuel property effects on both gasoline-based and diesel-based HCCI performance and emissions was completed. The results were published showing that the fuel properties could in fact expand or shrink the HCCI operating space in the case of gasoline fuels. For diesel-like fuels, the results show how the cool-flame reactions are prominent in fuels with high cetane number. To more globally facilitate and coordinate research in this area, ORNL conceived a vision to initiate a comprehensive project on how fuel properties affect advanced combustion processes like HCCI, and teamed with NREL to move the project plans forward. The effort will begin with design of a research fuel matrix via a working group of experts in this field convened under the auspices of the Coordinating Research Council. The project has been named “FACE,” (Fuels for Advanced Combustion Engines).
ORNL supports the OFCVT Systems Team in cost-modeling for advanced vehicle components, and in developing performance ⁄ emissions models for engine and exhaust aftertreatment components. In FY 2005, the efforts were redirected to aid the development of the PSAT code in conjunction with Argonne National Lab. Johney Green, FEERC group leader, has been appointed to the FreedomCAR Systems Tech Team and serves as a liaison to the Advanced Combustion and Emission Control Tech Team.
In Environmental Science and Health Impacts, FEERC assists in determining the potential adverse impacts of new technologies being developed in OFCVT. The Watt Road Environmental Laboratory received funding by the OFCVT ESH activity for real-world truck emissions studies. EPA and DOT have co-sponsored certain studies at the field laboratory. Ambient sampling of PM and formaldehyde near the truck stop has shown a strong variation throughout the day and dependence on ambient conditions. In-cab emissions sampling has shown the impact of nearby idling trucks vs. the in-cab levels just from idling the subject truck.
FEERC staff members are actively supporting the Advanced Reciprocating Engine System (ARES) program by working on multiple projects in support of the DOE 2010 program goals of a 50% efficient natural gas (NG) stationary power engine with 0.1 g/bhp-hr NOx emission levels and reliability comparable to today's engines. The ORNL ARES work falls within three general areas: ignition, controls, and emissions and is highly leveraged with complimentary work for the Distributed Energy Materials program and work with the OFCVT. ORNL collaborates with engine manufacturers, system suppliers, end-users, and universities. Our basic approach is to provide a better understanding of the fundamentals of the key selected areas and then implement and evaluate these new technologies on ARES-class engines.
Specific accomplishments and on-going tasks follow:
- The development of a unique optical technique for investigating spark plug erosion and failure which when combined with metallurgical analysis provides new understanding and insight into spark plug erosion and failure.
- With Champion, new spark plug alloys are being developed and evaluated in a NG engine at ORNL. The goal is to more than double the life of spark plugs.
- Dilute operation of IC engines through lean fueling and/or high levels of EGR can increase fuel efficiency and reduce NOx emissions. An obstacle is unstable combustion accompanied by large cycle-to-cycle variations. Observations that these variations are dominated by deterministic processes has led new approaches and models for improving lean combustion stability. Previous control experiments have been performed on a small single-cylinder research engine, and control techniques will be implemented on a more ARES representative single-cylinder engine with 3.0-L displacement in FY 2006.
- ORNL has also demonstrated the effectiveness of a Lean NOx Trap catalyst system for meeting the DOE ARES NOx reduction target and has developed a much more complete understanding of this system.
There were a number of other new projects involving FEERC staff and facilities, mentioned briefly below:
- Lean-NOx catalysis reductant experimental study for private sector sponsor
- Experimental study of catalysts for HCCI exhaust for private sector sponsor
- Experimental study of HCCI vs. spark ignition combustion with hydrogen fuel (internal lab funds)
- Emissions characterization of idling trucks at Mexican-US border entry point
- Characterization of aircraft emissions (on ground)
- Assessment of ceramic valves in stationary natural gas engines
- Application of phosphor thermography for valve temperature measurements in large stationary engine
For FY 2006 and beyond, FEERC expects to continue activities in the Combustion MOU with increased emphasis on engine efficiency improvements. In fuel technologies, matching fuel properties to advanced combustion will be addressed in the FACE project. In parallel, the critical remaining issues in emission controls must be addressed. We expect CLEERS to remain a focal point of those efforts.
Thanks for visiting our website. If you have specific questions or comments about anything you see here, please do not hesitate to contact the PI or me.
Ron Graves
January 2006
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