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30-11-2017 | Engine Technology | News | Article

Challenges Posed by Large Engines

Andreas Fuchs
3 min reading time

Efficiency and exhaust emissions regulations are still driving the heavy-duty engine industry. The motto "Efficiency and Emissions" of the 12th International MTZ Conference on Heavy Duty, On- and Off-Highway Engines reflects these challenges. 

There are also other industry-specific driving forces. In his keynote speech, Dr. Christian Poensgen from MAN Diesel & Turbo SE presented challenges facing manufacturers of stationary engines for the power generation and marine engine sectors. In this decade for example, engine development at MAN has been subject to a period of substantial restructuring among customers and regulations. As a result, the last few years have been marked by the changeover and redevelopment of engines to gas and dual-fuel capabilities. 

To achieve this, MAN’s product range was extended by a 5-litre high-speed engine in the lower class (1-4 MW). At the same time, all engines were converted to IMO’s NOx specifications from Tier II to Tier III. SCR solutions have been developed that can be used both downstream of the engine and between the turbines for two-stage turbocharging, or upstream of the turbocharger’s turbine for two-stroke engines. 

Hybridisation is the impending challenge 

The concurrent changeover from PLD injection systems to CR systems made it possible to significantly improve engine efficiency, to support the regeneration of exhaust gas aftertreatment and to achieve significant fuel consumption benefits by integrating the conventional powertrain system. Dr. Poensgen also predicted additional challenges for engine manufacturers in future, such as hybridisation of powertrains, unmanned shipping, and fuel conversions within the framework of the IMO sulphur limit values.

In the subsequent first conference session “Medium Speed Engines”, Dr. Udo Schlemmer-Kelling from FEV Europe GmbH also addressed the challenges facing the shipping industry in his speech "Agenda 2030 – Mega Trends in the Large Bore Marine Engine Business". Until 2000, the main driving forces in the marine sector in terms of the development of large engines were plant reliability, acquisition and operating costs, as well as ease of maintenance. However, from the new millennium onwards, another issue was added: the gradually tightening emissions limits. 

Increasingly stringent emission limits

NOx limits of 2 g/kWh have been stipulated since 2016, and SOx emissions will also be limited to 5,000 ppm in 2020. For CO2, an overall EEDI index is calculated based on fuel consumption. It is different for each type of vessel, and is reduced by 10 percent every five years. Due to these measures, the limits for some components have, since 2015, been reduced to the point that the limits can no longer be met within the engine. This has required an exhaust gas aftertreatment system for diesel engines, resulting in rising acquisition and operating costs. "As a result of the immense cost pressure, most operators will therefore always prefer the most cost-effective solution that barely meets the laws currently in force", Dr. Schlemmer-Kelling said. From today’s perspective, this seems to be a fuel based on mineral oil. "There are some areas where gaseous fuels are a sensible alternative. But they will probably not become mainstream", Dr. Schlemmer-Kelling concluded.

The second session was then devoted to three presentations on new heavy-duty engines for diesel, LNG and hydrogen fuel types. Falko Arnold of MAN Truck & Bus showcased a new off-road engine based on the D3876. Cost-effective development is essential particularly in the off-road sector, with its few machines. For this reason, solutions derived from road traffic are often transferred to mobile machines. MAN has developed its D3876 inline six-cylinder engine for heavy commercial vehicles, agricultural applications and construction machinery. While the basic powertrain and fuel injection for on- and off-road versions are identical, turbocharging, combustion, electronics and exhaust gas aftertreatment differ according to the application, as Falko Arnold pointed out in his presentation. The new engine is available in the 415 kW to 485 kW (564 to 660 hp) power range, provides up to 3,100 Nm of torque, and meets EU Stage IV and US Tier 4 final requirements. 

The detailed conference report is available in the MTZ 3/2018, which will be published on 9 February 2018.

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Background information for this content

01-06-2017 | Cover Story | Issue 2/2017

“Diesel engines could drive clean”

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