Greater efficiency, more power: The new Series 4000 natural gas engines

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1 Background Greater efficiency, more power: The new Series 4000 natural gas engines Whether in electricity generating sets or as modules in combined heat and power plants, Series 4000 gas engine systems have been reliably providing power for many years. Now, the advanced-development version of the Type L64 natural gas engine means that in future, customers can generate decentralized power even more efficiently. Building on improvements already implemented in the current series, specific technology modules have been optimized in order to further increase the efficiency and electrical power offered by the engine series. At a time when the global demand for energy is rising and reliable electricity supplies are increasingly vital, power generation products have to meet particularly exacting demands. As well as long service life and low maintenance costs, high levels of efficiency and power density are crucial. In addition, these products must be able to cope with the increasingly stringent demands of future emissions legislation. The new, performance-enhanced natural gas engines from MTU Onsite Energy meet all these requirements. The current series has been consistently reworked using new information gained during pre-development and fullengine tests and the results include an electrical efficiency rating of 44.3% and increases of up to 30% in electric power in comparison with predecessor units.

2 This power and efficiency superiority over Model Type L63 means significant economic benefits for operators across the entire range of Series 4000 L64 cylinder configurations. This is particularly impressive at the 1,999kW el performance point which is key in the German market. Previously, a 20-cylinder Type 20V 4000 L63 engine with an electrical efficiency rating of 41.7 (as per ISO 3046) was needed to achieve this threshold point as defined in legislation for the promotion of combined heat and power technologies. In future, a 16-cylinder Type 16V 4000 L64 will achieve the same thing. Depending on fuel price and given an annual runtime of 7,500 hours, an electrical efficiency rating of 44.3% can translate into a yearly reduction in fuel costs of up to 100,000. In addition, the enhanced performance brings further benefits in terms of specific maintenance outlay. MTU Series 4000: Solid reliability over time The 4000 engine series is one of MTU s most successful product families. Since their introduction in 1996, Series 4000 units have been demonstrating their outstanding capabilities across a range of demanding applications. First available with a program of highspeed diesel engines, the product portfolio was extended at the beginning of 2001 to include gas engines for natural gas applications. Further extension came in 2011 in the shape of biogas engines powered by methane-based fuel gases produced by the anaerobic fermentation of organic materials. From their inception, MTU has continually developed and improved its Series 4000 natural gas units. Across a significant sector of its performance range, the latest engine generation represents a milestone in terms of electrical efficiency: with a per cylinder capacity of 4.77 liters it is capable of producing 2.5 MW el a first in its class. Like its predecessors, the new unit is specifically designed for unrestricted continuous operation in stationary power generation applications and with a runtime of 63,000 hours before

3 major overhaul becomes due, these engines are among the most robust in their performance class. One crucial issue during the further development process was the specification that already existing components should be used as far as possible in order to keep manufacturing and assembly costs as well as customer outlay for spare parts to a minimum. The engines are integrated in distributed power generation systems produced by MTU Onsite Energy and produce 1,000 to 2,500 kw el. Series 4000 Type L64 engines have been available since April 2014 with the 12 and 16-cylinder models appearing first, followed by the 20 and 8-cylinder versions in succession. Further development of series 4000 natural gas engines Previous model types already saw the integration of significant improvements in de-throttling, turbocharging, combustion, electronics, ignition and crank-drive technology, all of which contributed to greater engine efficiency. To enhance efficiency and power even further, MTU conducted trials on a single-cylinder unit using fluid-mechanical 3D simulations (CFD simulations [Computational Fluid Dynamics]) to facilitate continuous checks on the effects on the engine at a later stage. A genset was installed at the company s Friedrichshafen location at an early stage in the project to ensure that sufficient experience with continuous operation could be gathered with the new performance-enhanced model. At the Friedrichshafen site, two combined heat and power (CHP) modules powered by MTU gas engines have now been supplying thermal energy and electricity for the facility s production section for several years. Since January 2012, the CHP plant in Works 2 has been operating with one of the new engines at a specific continuous power of 130 kw per cylinder. And to guarantee safe and reliable series start-up, MTU is also running a field trial under actual working conditions.

4 Optimized components reduce pressure losses An important element in the development of the new gas engine was the de-throttling of components carrying gas in order to minimize pressure losses. To achieve this aim, the elbows, gas mixer and the mixture cooler were fluidically optimized. As a result, for example, the modified shape of the exhaust manifold reduces exhaust counter-pressure downstream of the turbine and significantly decreases flow losses in the exhaust line with a positive effect on engine efficiency. Improvements in combustion To improve anti-knock characteristics and reduce nitrogen oxide emissions, MTU employs the Miller process: advancing the closing point of the inlet valves results in a cooling of the mixture and a consequent decrease in maximum combustion temperatures. By combining this with an increase in valve lift (inlet and exhaust) and reduced swirl, MTU has been able to simplify the gas-exchange process which in turn has a positive influence on engine efficiency. Further improvements in efficiency were achieved by modifying the geometries of the piston bowls and pre-chamber ignition plugs and minimizing dead space in the combustion chambers. Efficient turbocharging for high-performance engines The Series 4000 L64 employs single-stage, bypass-controlled turbocharging with ABB A100 series turbochargers. The improvements in turbocharging efficiency which have now been achieved allow MTU to dispense with complex and expensive twostage turbocharging systems. Compressor cooling is available as an option. This involves recirculating some of the cooled and compressed mixture mass flow to the back wall of the compressor to cool it. As a result, the turbocharger functions more efficiently

5 and the engine can work at rated power at altitudes 600 meters higher than would otherwise be the case. Powerful engine management For the performance-enhanced 4000 units, MTU adapted the control software already available in order to improve load switching capability. The latest generation of MTU s own engine controller platform facilitates even more precise control of bypass and fuel throttle functions. In addition, the engine management system can process electrical factors even more rapidly so that response to load changes is further accelerated in some cases, even before they have had a chance to influence the engine. The new control system is also able to run an automated, unmanned test stand sequence producing data which can be used during series acceptance procedures and on R&D test stands to enhance test run efficiency. In the long term, development engineers and customers both stand to benefit. Illustrations: Infobox engine data Rated engine speed 1,500rpm Mean effective pressure 21.8 bar Electrical efficiency (ISO 3046) 44.3% Bore / Stroke 170/210 mm Cylinder Vee-angle 90 Cylinder capacity 4.77 liters Mechanical power per cylinder 130kW Cylinder configurations 8V, 12V, 16V and 20V Emissions-optimization ½ TA Luft and TA Luft - End -

6 About MTU Onsite Energy MTU Onsite Energy is a brand of Rolls-Royce Power Systems AG. It provides diesel and gas-based power system solutions: from mission-critical to standby power to continuous power, heating and cooling. MTU Onsite Energy power systems are based on diesel engines with up to 3,400 kilowatts (kw) power output, gas engines up to 2,530 kw and gas turbines up to 50,000 kw. About Rolls-Royce Power Systems Rolls-Royce Power Systems AG, based in Friedrichshafen, Germany, is a worldleading provider of high- and medium-speed diesel and gas engines, drive systems, distributed energy systems and fuel injection systems for the most demanding requirements. Rolls-Royce Power Systems AG previously operated under the name of Tognum AG. The product portfolio includes MTU-branded high-speed engines and drive systems for ships, heavy land, rail and defense vehicles and for the oil and gas industry. Under the MTU Onsite Energy brand, the company sells diesel and gasbased power system solutions: from mission-critical to standby power to continuous power, heating and cooling. The Norwegian subsidiary Bergen Engines AS manufactures medium-speed engines for ships and power plants. L'Orange completes the portfolio with injection systems for large engines. Rolls-Royce plc and Daimler AG each has a 50% shareholding in the company via a joint venture Rolls-Royce Power Systems Holding GmbH. The company, which employs over 10,000 people, has been fully consolidated in the results of Rolls- Royce plc since January 2013.