24 September 2010
This year’s ASME Internal Combustion Engine Division Fall Technical Conference was held on September 12-15, 2010 at the Hilton Palacio del Rio in San Antonio, Texas. It was hosted by Southwest Research Institute. There were 183 registered attendees and 99 presentations.
The conference started with a keynote address by Dr. Thomas Ryan III of Ryan Consultants LLC. He discussed potential technologies for improving the fuel efficiency of light- and heavy-duty vehicles. A number of engine technologies that could potentially be incorporated into light-duty engines could provide customer savings of around 7,000 Euros over an assumed 10 year vehicle lifetime while meeting a 130 g/km CO2 limit. For on-road heavy-duty applications, vehicle technologies such as measures to reduce aerodynamic drag and rolling resistance are more effective than just engine measures alone. A 20% reduction in CO2 was estimated to be possible by 2030 from line-haul trucks. Even short ownership periods from 2-5 years offer potential savings for truck owners from some of these measures.
Locomotive Engines. With the EPA Tier 4 locomotive implementation date coming into effect in 2015, development and engineering work is well under way to meet its challenging limits. During a lunch time presentation, Michael Iden of Union Pacific Railroad presented a railway’s perspective of considerations that should be taken into account for the design of these locomotives. Some of the issues he brought forward included:
- The major outside dimensions of a locomotive have to be maintained at current values. Locomotives are shared across the U.S., Canada and Mexico so they need to be compatible with the current infrastructure. They also have to fit inside the AAR Plate-L clearance dimensions to ensure coal deliveries to electric power plants can be maintained. Double stack container cars are occasionally pointed to as evidence that locomotive height can be increased. However, these cars are strictly limited to certain routes were bridge/tunnel clearances are sufficient.
- Placing aftertreatment systems high on the locomotive will make maintenance work more difficult because of the need for fall prevention safety measures to protect maintenance workers.
- Additional piping, joints etc. will have to be designed to ensure exhaust leaks in the car body of the locomotive do not occur.
- The fuel capacity of the locomotive needs to be sufficient to ensure current operating ranges between scheduled fuel stops can be maintained. An additional urea tank located next to the fuel tank can necessitate the use of a smaller fuel tank.
- Engine maintainability needs to be ensured. Removal of power cylinder assemblies often required the use of over-head cranes and aftertreatment placed immediately above the engine can interfere with this operation.
Joint studies by GE Transportation and Southwest Research Institute covered several pertinent issues. One study carried out with the added participation of Da Vinci Emissions Services, Ltd. identified the cylinder liner design as the most important factor influencing oil consumption (and therefore the lube oil derived portion of PM emissions) for cylinder rebuild kits intended to allow existing locomotives to meet EPA Tier 0+ emission standards. Piston ring design also had a significant but smaller effect [ICEF2010-35199]. Another study looking at the influence of biodiesel blends on emissions from a Tier 2 locomotive found that PM was consistently reduced and volumetric fuel consumption increased with blends as low as B2 but that NOx emission increases did not exceed test-to-test variability until the blend level exceeded B20 [ICEF2010-35024].
Another study by GE Transportation examined the influence of Miller cycle valve timing, turbocompounding and a combination of the two on fuel consumption in a medium speed diesel engine. Combining the two technologies seems to have little benefit over turbocompounding alone because the decrease in effective compression ratio resulting from the Miller cycle leads to lower pre-turbine exhaust availability that decreases the potential benefit of turbocompounding [ICEF2010-35085].
Fuel Efficiency. With the major reductions in emissions from new light- and heavy-duty on-road mobile applications that have been achieved in the past decade, the focus of technological developments is moving away from emissions reductions towards fuel efficiency improvements and CO2 reductions. This shift was apparent in many of the presentations at this year’s conference.
Waste Heat Recovery. One potential source of efficiency improvement is through the recovery of additional work from waste heat in the exhaust. Michigan Technological University reviewed waste heat recovery using two emerging technologies: organic Rankine cycle (ORC) and thermoelectric devices. They identified a number of factors that need to be considered for the successful application of these technologies to transportation applications. The application of ORC to heavy-duty applications seems to be the most attractive application of waste heat recovery with thermal efficiency improvements of about 18% possible [ICEF2010-35142].
The application of ORC to light-duty applications, however, offers more modest thermal efficiency improvements of 2-3% due to driving cycle differences according to researchers at Oak Ridge National Laboratory. An important technical barrier is the need to manage the limited thermal energy in the exhaust gases so that NOx aftertreatment catalysts continue to have sufficiently high temperature to operate effectively [ICEF2010-35120].
Downsizing. Another design trend for achieving fuel efficiency gains is engine downsizing. A joint program between the Conservatoire national des arts et métiers (Cnam), Honeywell, Peugeot and Renault discussed the need to characterize turbocharger performance at low speeds such as might be experienced in urban driving [ICEF2010-35071]. Downsized engines will also experience higher bearing loads and may need improved bearing materials such as Federal Mogul’s IROX™ bearing technology to ensure downsized engines do not suffer from premature bearing failure [ICEF2010-35114]. Higher power densities in downsized engines can increase coolant temperatures and according to Seals Eastern, Inc., some of the current elastomer materials used for cooling system seals may not be compatible [ICEF2010-35074]. Higher temperature cooling systems can utilize the higher heat transfer coefficient available from nucleate boiling to improve cooling system efficiency and reduce engine warm-up times but must contend with a more difficult control problem. Researchers at the Michigan Technological University suggested that a pressure based control method can avoid performance variability and overheating [ICEF2010-35118].
On the third day of the conference, two technical tours were organized: to the Southwest Research Institute, one of the oldest and largest independent research organizations in the United States, and to the San Antonio Toyota Tundra plant.
Future ASME ICE conferences will be held in Morgantown, WV, USA in the Fall of 2011, followed by Torino, Italy in the Spring of 2012.
Conference website: www.asmeconferences.org/ICEF2010