The Wärtsilä RT-flex96C is a two-stroke turbocharged low-speed diesel engine manufactured 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 five stories (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 (81.3 MW).
It was put into service in September 2006 aboard the Emma Mærsk.[1] The design is based on the older RTA-96C 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. As of 2008, the power output of the 14 cylinder version has been increased to 84.42 MW (114,800 bhp).
The engine has crosshead bearings. 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 that the always vertical piston rod allows a tight seal under the piston. 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.
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Technical data (as of 2008)
- engine configuration
- turbocharged two-stroke diesel straight engine, 6 to 14 cylinders
- cylinder bore
- 960 millimetres (37.79 inches)
- piston stroke
- 2500 millimetres (98.42 inches)
- engine displacement
- 1820 litres per cylinder (111,063 cubic inches)
- engine speed
- 92–102 revolutions per minute
- torque
- 7,603,850 Newton metres @ 102 revolutions per minute (5,608,312 Footpounds)
- 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 gram/kW·h (126 gram/bhp·h, approx. 3.80 litres/second) @ full load; 163 gram/kW·h (120 gram/bhp·h) @ maximum efficiency
- power
- up to 6030 kW per cylinder, 36,180 to 84,420 kW (49,200 to 114,800 bhp) altogether
- power density
- 29.6 to 34.8 kW per tonne, 2301 tonnes for the 14 cylinder version
- amount of fuel injected in a single cycle of single piston
- ~160 grammes @ full load
Efficiency
The specific fuel consumption efficiency of the RTA96 is 5% worse than the Man S80ME-C7.[3] However, S80ME-C7 has much lower power rating than RTA96-C. An equal sized 14-cylinder MAN MC7 (87 220kW) has a minimum SFOC-rating of 164-170 g/kWh at partial load.[4]
See also
- Diesel cycle
- Forced induction
- Indirect injection
- Direct injection
- Turbocharger
- Dieselisation
- Diesel generator
- Junkers Jumo 205—The more successful of the first series of production diesel aircraft engines.
- 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
- ^ Wärtsilä Corporation (2006-09-12). "The world's most powerful Engine enters service". Press release. http://www.wartsila.com/,en,press,0,tradepressrelease,8F51527F-00A3-4C5F-ABEA-B543789ACA1B,26EE6684-06C9-48B3-920A-3B238B7C302A,,.htm.
- ^ MarineLink.com (2001-03-15). "Increased power for the Sulzer RTA96C". Press release. http://www.marinelink.com/Story/Increased+power+for+the+Sulzer+RTA96C-5103.html.
- ^ MAN Diesel SE - Marine Low Speed Engines: S80ME-C7
- ^ MAN Diesel SE - Marine Marine Engine, IMO Tier II, Programme 2009PDF
External links
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