Wärtsilä-Sulzer RTA96-C
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The Wärtsilä RT-flex96C is a two-stroke turbocharged low-speed diesel engine designed by the Finnish manufacturer Wärtsilä. It is currently considered the largest reciprocating engine in the world, designed for large container ships, running on heavy fuel oil. It stands at 13.5 metres (44 ft) high, is 27.3 m (90 ft) long, and weighs over 2300 tonnes in its largest 14-cylinder version — producing 109,000 brake horsepower (80,08 MW).
The 14-cylinder version was put into service in September 2006 aboard the Emma Mærsk.[1] The design is based on the older RTA96C engine,[2] but revolutionary common rail technology has done away with the traditional camshaft, chain gear, fuel pumps and hydraulic actuators. The result is better performance at low revolutions per minute (rpm), lower fuel consumption, and lower harmful emissions.
The engine has crosshead bearings so that the always vertical piston rod allows a tight seal under the piston. One of the reasons that the large two-stroke diesels use this design is so that the lubrication in the combustion area is separated from the crank case oil, which stays clean from combustion products. The upper portion is lubricated by continuous injection of consumable lubricant which is formulated to stand up to high temperatures and high sulfur. Another reason is to reduce sideways forces on the piston, keeping diametral cylinder liner wear in the order of only about 0.03 mm per 1000 hours.[3]
The descending piston is used to compress incoming combustion air for the adjacent cylinders which also serves to cushion the piston as it approaches bottom dead centre (BDC) to remove some load from the bearings.
In service are 25 engines, and 86 are on order.[3]
Technical data (as of 2008)
- engine configuration
- turbocharged two-stroke diesel straight engine, 6 to 14 cylinders
- cylinder bore
- 960 mm
- piston stroke
- 2500 mm
- engine displacement
- 1820 litres per cylinder
- engine speed
- 92–102 revolutions per minute
- torque
- 7,603,850 newton-metres (5,608,310 lbf⋅ft) @ 102 rpm
- mean effective pressure
- 1.96 MPa @ full load, 1.37 MPa @ maximum efficiency (85% load)
- mean piston speed
- 8.5 metre per second
- specific fuel consumption
- 171 g/(kW·h) (126 g/(bhp·h), approx. 3.80 litres per second) @ full load; 163 g/(kW·h) (120 g/(bhp·h)) @ maximum efficiency
- power
- up to 5720 kW per cylinder, 34320 to 80080;kW (46 680 to 108 920 bhp) altogether
- power density
- 29.6 to 34.8 kW per tonne, 2300 tonnes for the 14 cylinder version
- amount of fuel injected in a single cycle of single piston
- ~160 g (about 6.5 ounces) @ full load
- crankshaft weight
- 300 tons[3]
Efficiency
An equal MAN engine in terms of stroke, rated speed, power and technology is the 14-cylinder K98ME7 (87 220 kW) that has a minimum SFOC-rating of 164 g/kWh at partial load.[4]
See also
- Forced induction
- Indirect injection
- Direct injection
- Turbocharger
- Dieselisation
- Diesel generator
- Napier Deltic—a high-speed, lightweight diesel engine used in fast naval craft and some railway locomotives.
- History of the internal combustion engine
- Hesselman engine
References
- ^ "The world's most powerful Engine enters service" (Press release). Wärtsilä Corporation. 2006-09-12.
- ^ "Increased power for the Sulzer RTA96C" (Press release). MarineLink.com. 2001-03-15.
- ^ a b c Hanlon, Mike. Most powerful diesel engine in the world GizMag. Accessed: 24 February 2011.
- ^ MAN Diesel SE - Marine Template:PDF