Heavy-Duty-, On- und Off-Highway-Motoren 2014

The growing global population and increasing standard of living produce a strong demand growth in power supply and distribution. Power needs to be supplied at or near the source of demand particularly in developing countries. Beyond baseload applications, growth in intermittent renewables and transient demand shifts require efficiency in flexible, peak-shaving and grid stabilization power supply. Reciprocating engines have undergone strong and sustained development over the past decades and today feature key characteristics suitable for distributed power: high simple-cycle efficiency, even at part load, lower de-rate with varying ambient conditions, modular power blocks that can be expanded as demand grows, low emissions, low water usage and attractive life-cycle costs. As demand for flexible, distributed power grows, this will drive the development of reciprocating engine technologies further into fast ramp-up and load shedding, part load operation and grid stabilization. Furthermore, a wider quality of base fuel and increasingly stringent emissions requirements increase the challenge to continue efficiency gains in development. Control system developments and the evolution of the industrial internet open new doors to efficient operation, predictive maintenance, and optimization of assets and fleets.

To improve exhaust heat utilization of a turbocharged engine, divided exhaust period (DEP) and turbocompound are integrated. The DEP concept decreases pumping loss created by the turbocompound. In the DEP concept the exhaust flow is divided between two different exhaust manifolds, blowdown and scavenging. One of the two exhaust valves on each engine cylinder is opened to the blowdown manifold at the first phase of exhaust stroke and the other valve is opened to the scavenging manifold at the later phase of exhaust stroke. This leads to lower exhaust back pressure and pumping loss. The combination of turbocompound engine with DEP has been examined previously and the result showed that this combination reduces the fuel consumption in low engine speeds and deteriorates it in high engine speeds. The main restriction of this combination was the low effective flow areas of the exhaust valves at high engine speeds.

To overcome this restriction and increase the effective flow areas of the exhaust valves, DEP is employed externally on the exhaust manifold instead of engine exhaust valves. In externally DEP (ExDEP), both exhaust valves will be opened and closed similar to the corresponding turbocharged engine and the exhaust flow is divided by flow splits on the exhaust manifold. Two valves on the outlet ports of each flow split are added. One of them is a non-return valve (check valve) and the other one is synchronized with the cam shaft.

In this study, the fuel-saving potential of ExDEP is analysed on the turbocompound engine at different engine speeds and loads and compared with the corresponding turbocharged engine, turbocompound engine and turbocompound DEP engine equipped. The results show that ExDEP has a great fuel-saving potential in almost all load points.

ExDEP concept, itself, is a novel concept that there is no available literature about it. Moreover, combination of this new gas exchange system with turbocompound engines is an innovative extension of combined turbocompound DEP engines.

Natural gas offers some advantages compared to diesel fuel: reducing operational costs and at the same time respecting tight emission regulations without complex exhaust gas aftertreatment systems. While lean burn gas engines are already widely used for stationary applications, there is a strong motivation to develop high-bmep gas engines for demanding applications such as marine propulsion, off-highway traction, compressor drive, etc. In order to satisfy the specific application characteristics such as highly dynamic engine performance and a wide operation map, new engine control concepts need to be developed to respond to these requirements and mitigate specific gas engine challenges such as knocking combustion.

On its 62nd session the Maritime Environmental Protection Committee (MEPC) of the International Maritime Organisation (IMO) adopted guidelines addressing additional aspects to the NOx Technical Code 2008 with regard to particular requirements related to marine Diesel Engines fitted with Selective Catalytic Reduction (SCR) systems. Following these guidelines a combined engine and SCR can be tested separately in cases where the combined system can neither be tested on a test bed due to their size, construction and other restrictions nor an on board test can be performed fully complying with the requirements of the NOx Technical Code. This certification procedure has been referred to as the “Scheme B approach”.

MAN designed all D2868/62 marine engines to meet the EPA Tier 3 emission standard without exhaust after-treatment. The EPA Tier 3 emission standard was introduced for displacements of 1.2 – 2.5 l/cylinder from 2014-01-01 onwards.

Within the modification of the current marine engines to meet the EPA Tier 3 standard, the gas exchange cycle was optimized. This was mainly achieved by introducing new camshafts based on the Miller cycle. Therewith the fuel consumption was reduced by up to 7% at rated power (referring to equal NOx emissions) and up to 5% at rated power comparing EPA Tier 2 previous design and EPA Tier 3 new design.

Clients in the stationary gas engine business are asking for increased engine efficiencies, and in parallel, more robustness against failures, extended service intervals and reduced unexpected engine shutdowns.

Seit Ende 2008 entwickelt die Firma L‘Orange GmbH gemeinsam mit der Firma Wärtsilä Switzerland Ltd. Common-Rail Einspritzinjektoren und Hochdruckpumpen für Zweitakt-Großdieselmotoren. Die Zweitakt-Großdieselmotoren der Firma Wärtsilä stellen eine Familie von Motoren in der Zylindergröße von 35 bis 92 cm im Durchmesser dar, die mit Injektoren der L’Orange-‚Injektorfamilie‘ ausgestattet sind beziehungsweise werden. Die Herausforderung bei der Entwicklung war, dass für sieben Motorbaureihen unterschiedlicher Zylindergrößen, in einem Leistungsbereich von 870 bis 6.130 kW/Zyl., nur insgesamt drei verschieden Baugrößen von Einspritzinjektoren eingesetzt werden sollten.

Carrying over the major trend of downsizing from passenger car to commercial engines is not entirely possible due to several reasons. One reason is that commercial engines have to comply with the most stringent exhaust gas emission limits also at full load. Another one is a much higher requirement regarding the life time of the engine. Both reasons limit the achievable specific performance to a rather low level compared to passenger car engines. Nevertheless development engineers are challenged more than ever with the need to reduce fuel consumption, size and weight of heavy duty engines. Moreover this has to be fulfilled at acceptable engine costs. This paper shows a possible path of how to combine the advantages of downsizing with the requirements of a commercial engine. This is achieved by reducing the number of cylinders but keeping the total displacement of the original engine.

In the last 10 to 15 years, the growing concern over global warming has led to the promulgation of legislation on fuel consumption for heavy-duty vehicles. In the USA, emissions standards have been introduced for Green House Gases (GHG) , namely carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄) emissions. Japan and China have also introduced fuel consumption regulations. The European Commission (EC) is expected to publish proposals for the control of CO₂ from or fuel consumption by heavy-duty vehicles that will lead to a regulation in 2019 or 2020.

Höhere Effizienz und die Reduzierung der Emissionen stehen für die Entwickler von Heavy-Duty-Motoren für On- und Off-Highway-Anwendungen weltweit auch künftig im Pflichtenheft. Dabei spielt die Gesamtsystembetrachtung eine zunehmend wichtigere Rolle. Führende Experten gaben den über 200 Teilnehmern auf der 9.