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Conference report: ASME 2013 ICE Fall Technical Conference

29 October 2013

The ASME Internal Combustion Engine Division 2013 Fall Technical Conference was held October 13-16, 2013 at The Dearborn Inn in Dearborn, Michigan and was hosted by Wayne State University. Even with the absence of US government employees that were unable to attend due to the US government shut-down, there were 217 registered attendees, 67 of which were students. The two-day technical program included almost 100 technical papers. On the third day, participants could attend a tour of Wayne State University’s engine research facilities.

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Keynote Lecture. The conference started with a keynote address by Tom McCarthy, Chief Engineer for Powertrain Research & Advanced Engineering at Ford. The presentation entitled "Systems Approach to Making Optimal Powertrain Technology Choices—A Global OEM’s Perspective", focused on some important drivers that a large global vehicle manufacturer must consider in making powertrain technology choices.

One driver is the customer. Customers have a wide range of powertrain options including conventional internal combustion engines fueled by petroleum fuels and/or alternative fuels, hybrids and battery electric technologies. Ultimately, for a powertrain option to be successful it must provide some value to the customer or people will simply not buy it. Factors considered important by customers include: total cost of ownership, vehicle purchase price, vehicle range and whether the infrastructure for operating the vehicle is available.

Another driver is regulation. While there are important global differences in vehicle greenhouse gas emission requirements, there are also regional differences in vehicle taxation and criteria emissions.

A third driver is the technology used in the vehicle itself. An important consideration when trying to reduce energy flow losses from the powertrain is that in some cases, these losses serve useful functions and it may not be desirable to eliminate them completely. For example, reducing the heat expelled out of the exhaust system can create challenges with heating and maintaining exhaust aftertreatment system temperature. Some of the advanced technologies important for efficiency gains that were mentioned included advanced combustion, variable valve timing, turbocharging, cooled EGR, variable displacement oil pumps, reduced power cylinder friction and fast warm up technology such as thermal storage, advanced cooling and thermal electrics. Vehicle electrification will grow; primarily through wider availability of HEV or PHEV rather than BEVs. The internal combustion engine will remain at the core of the passenger vehicle for a long time to come. Another technology consideration is ensuring that engine operation at the peak efficiency load/speed condition is maximized. Hybrid vehicles with energy storage offer significant benefit in this regard because of their capability to manage and time-shift power demand. Future improvements in fuel economy will still require significant improvements in ICE efficiency. Advanced SI engine developments will follow two distinct paths: a HEV path and a gasoline turbocharged direct injection path.

A fourth driver is the need to make a good business case for any technology choice. One big challenge in this regard is that there can be diminishing customer value with increasing technology levels and diminishing customer value with decreasing annual fuel cost. Technology costs are additive but the savings that these technologies offer the customer are not. Adding more technology offers diminishing fuel savings and the less a customer spends on fuel annually, the harder it is to realize cost savings that would offset the cost of the technology.

Engine Design. A number of papers related to engine design issues were presented by Mahle. In one, a new piston pin design with an oval piston pin bore was presented as a solution to piston pin joint ticking that can occur during engine warn-up [ICEF2013-19085]. Another paper suggested steel pistons could become more common in light-duty diesel engines. However, the driver is fuel consumption and CO2 legislation rather than increased component strength. Steel has some advantages such as a lower coefficient of thermal expansion that can be exploited to reduce friction—especially if the alternative aluminum piston goes into an overlap condition (i.e., the maximum radius of the piston exceeds the radius of the cylinder bore). Other benefits of steel pistons include the potential for smaller compression height and lower reciprocating mass, a reduced top land crevice volume that can yield lower cold start CO emissions and lower rates of deformation that can allow piston rings to seal better and reduce blow-by [ICEF2013-19114]. Other papers dealt with lead-free composite bearing overlays for heavy-duty applications [ICEF2013-19086] and fully nitrided valves for medium and heavy-duty engines [ICEF2013-19049].

Researchers at Tokyo City University were able to apply a laser induced fluorescence (LIF) technique through an optical fiber embedded in the oil control ring to measure the oil film thickness at the sliding surface of oil ring [ICEF2013-19153]. Oil ring conformability was also measured. Oil film thickness measurements at this location are very challenging and are most commonly estimated using numerical simulation. Film thicknesses of 2-14 micrometer were measured—considerably thicker than many modeling results would suggest.

Loughborough University presented a paper that studied combining a relatively new concept, turbo-discharging, with turbocharging and/or turbocompounding as a means of recovering exhaust gas energy [ICEF2013-19118]. Turbo-discharging uses turbine recovered exhaust energy to depressurize the exhaust system with the primary aim of reducing engine pumping work by reducing the pressure at which the gases are exhausted from the cylinder. In practice, an engine with 2 exhaust valves/cylinder is used and the exhaust flow from each valve is separated. One exhaust valve is opened to pass the blow-down flow to a turbine and recover the associated exhaust pulse energy. The second exhaust valve is opened during the main displacement flow and the turbine is by-passed so that the crankshaft does not have to do additional work exhausting the burnt gases through the turbine. The energy recovered by the turbine is then used to drive a centrifugal compressor downstream in the exhaust system to allow a depressurized exhaust system. The discharging effect can be increased by removing heat from the exhaust gases between the discharging turbine and compressor. For throttled stoichiometric gasoline engine architectures, when turbocharging was paired with either turbocompounding or turbo-discharging, the magnitude of the maximum efficiency benefit is similar; about 4%. However, turbo-discharging offers a peak benefit at low load conditions while the peak benefit from turbocompounding occurs at higher load conditions. The peak benefit with lean burn gas engines is smaller (about 2.6%) than for the stoichiometric gasoline engine while for diesel engines, benefits are marginal.

General Motors talked about the development and optimization of a spark-ignition direct injection (SIDI) “small-block” engine [ICEF2013-19168]. The SIDI technology was applied to a 6.2 liter V8 engine that, in the PFI version, is produced at high volumes for light truck applications. The engine offers advantages of compact design and high power density, but its two-valve architecture presented challenges for the application of the SIDI technology—the asymmetric configuration, with fuel injection at the side of the air intake valve, biases the interaction of the intake airflow with the fuel spray. Engine performance was optimized over the entire operating range including idle, cold-start, part and mid-load and wide-open-throttle (WOT) conditions. The conversion from PFI to SIDI yielded significant improvements in fuel consumption (6.5% reduction over the FTP test), idle combustion stability, cold-start HC emissions (70% reduction) and WOT performance (8-10% higher torque and 6% higher power). Soot emissions were very sensitive to the injector design. With optimization, nearly zero smoke emissions were achieved throughout much of the engine’s operating range.

Next year, the ASME Internal Combustion Engine Division 2014 Fall Technical Conference will be held on October 19-22, 2014 in Columbus, IN. The meeting will be hosted by Cummins Inc.

Conference website: asmeconferences.org/ICEF2013