ATZ Live—part of the publishing group behind MTZ and other technical magazines—organized a conference in Nuremberg, Germany last week with a focus on heavy-duty, on- and off-highway engines. I had the chance to attend this conference and also delivered a talk introducing our latest, exciting results.
The conference is an annual event and this year was the seventh time engineers from the heavy-duty engine industry got together. Over the years, the conference moved to the locations of the heavy-duty engine manufacturers. This year it was held in Nuremberg, which is the home of MAN. MAN is a traditional and well-known truck and bus manufacturer in Germany and we were invited for a tour through their engine plant. We saw the production line for their V-engine product for marine, power plant and other heavy equipment and also the production line for their in-line six engine for trucks and buses. In addition, MAN showed us the chassis dyno roll for the truck and engine dynos, where the Euro 6 product was finishing off the final durability runs before it’s rolled out next year.
The topic of the conference this year was: efficiency and emissions, how to optimize both. This topic is well-suited for our Achates Power opposed-piston, two-stroke diesel engine and so the presentation of our latest performance and durability results really resonated with the audience as we presented a best-point brake thermal efficiency of 46% for a medium-duty 4.9L engine. These results were achieved after just eight months of development and while demonstrating very low engine-out NOx and soot as well as a highly efficient, flat fuel map.
Some other highlights from the conference:
- Daimler presented the thermodynamic concept of the new medium-duty OM934/OM935 engine family. Mercedes-Benz developed this all new engine family for the upcoming Euro 6 emissions legislation. For emissions reduction to Euro 6, the engine has a high-pressure EGR system plus DPF and SCR. The new combustion system reduced the engine-out NOx by 13% compared to the EPA07 product from Mercedes-Benz. The soot reduction of 67% is very impressive and all this with a 7% reduction in fuel consumption. The demonstrated brake thermal efficiency was more than 45% for their 7.7L engine.
- MAN Truck & Bus AG spoke about how they manage the huge variation of the D2868/2862 V-engine—from V8 to V12, from truck to marine, from Euro 5 to Tier 4—using the same base engine.
- Many of the papers showed how OEMs and component suppliers are approaching the upcoming emission legislations in the off-road, power generation and maritime environments. A variety of technologies are thrown on this type of larger engine like the Miller cycle, EGR, two-stage turbocharging, aftertreatment, waste heat recovery, dual fuel and also the control aspect of it.
Overall, this was a very good conference for on- and off-road heavy-duty development engineers to exchange experiences and the technologies needed to address the challenges of the future. Since these new technologies to improve fuel efficiency will also benefit our engine, the Achates Power opposed-piston engine will maintain its advantages of increased efficiency and lower cost.
Gerhard, Do you have any detail on the thermal efficiency of the “large” engines for off-road, gen sets and marine? You listed some technologies but was anything presented by manufacturers on technology vs. BTE? Especially of interest is the large MAN two-stroke & four-stroke engine capabilities? Dave Merrion
Thank you for your question. At the conference, there wasn’t much talk about the absolute values of thermal efficiencies for marine engines under IMO Tier III emissions legislation. However, there was a paper on evaluating technologies for IMO Tier III and, especially, for the switching between IMO Tier II and Tier III for ECA (emission-controlled areas) and non-ECA. This was done on a 4-stroke engine and the paper demonstrates that there is improvement potential of about 3% BSFC by choosing the right technology, which also adds cost. So the trade-off between fuel and cost needs to be figured out by 2016.
For absolute numbers of 2-stroke cathedral engines, you can look at the catalogs from Wärtsilä and MAN. Wärtsilä’s best BSFC is 157.7 g/kWh for their RT-flex82T IMO T2 engine with 820 mm bore and 3375 mm stroke. This is a 4.1 stroke-to-bore ratio. MAN has a best BSFC of 155.5 g/kWh for the G80ME-C9 with a bore of 800 mm and a stroke of 3720 mm (S/B ratio = 4.65). These engines are the most efficient in the world and they are 2-strokes and have a huge stroke-to-bore ratio.
What are the two stroke long bore efficiencies?
These must have a poorer power to weight ratio?
How do determine a figure of merit for trading efficiency and weight when comparing designs.
Need a good EE on staff? (grew up reading motorcycle and hot rode magazines and love the ICE!)
What is the efficiency lost between ignition and when the crank angle starts producing power ~ 4,5,6,7 degrees ATDC do to thermal heat transfer and thuse pressure loss?
efficiency weight question…comments for both just the engine and in a vehicle requested. (assuming you can answer easily 🙂