Wärtsilä-Sulzer RTA96-C
Encyclopedia
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 ship
s, 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 tonne
s 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
. The design is based on the older RTA96C engine, but revolutionary common rail
technology has done away with the traditional camshaft
, chain gear, fuel pump
s 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.
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.
: 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
: 7603850 newton metres (5,608,312 ft·lbf) @ 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
Turbocharger
A turbocharger, or turbo , from the Greek "τύρβη" is a centrifugal compressor powered by a turbine that is driven by an engine's exhaust gases. Its benefit lies with the compressor increasing the mass of air entering the engine , thereby resulting in greater performance...
low-speed diesel engine
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...
designed by the Finnish
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
manufacturer Wärtsilä
Wärtsilä
Wärtsilä is a Finnish corporation which manufactures and services power sources and other equipment in the marine and energy markets. The core products of Wärtsilä include large combustion engines...
. It is currently considered the largest reciprocating engine
Reciprocating engine
A reciprocating engine, also often known as a piston engine, is a heat engine that uses one or more reciprocating pistons to convert pressure into a rotating motion. This article describes the common features of all types...
in the world, designed for large container ship
Container ship
Container ships are cargo ships that carry all of their load in truck-size intermodal containers, in a technique called containerization. They form a common means of commercial intermodal freight transport.-History:...
s, 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 tonne
Tonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
s 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
Emma Mærsk
Emma Mærsk is the first container ship in the E-class of eight owned by the A. P. Moller-Maersk Group. When she was launched in 2006, Emma Mærsk was the largest container ship ever built...
. The design is based on the older RTA96C engine, but revolutionary common rail
Common rail
Common rail direct fuel injection is a modern variant of direct fuel injection system for petrol and diesel engines.On diesel engines, it features a high-pressure fuel rail feeding individual solenoid valves, as opposed to low-pressure fuel pump feeding unit injectors...
technology has done away with the traditional camshaft
Camshaft
A camshaft is a shaft to which a cam is fastened or of which a cam forms an integral part.-History:An early cam was built into Hellenistic water-driven automata from the 3rd century BC. The camshaft was later described in Iraq by Al-Jazari in 1206. He employed it as part of his automata,...
, chain gear, fuel pump
Fuel pump
A fuel pump is a frequently essential component on a car or other internal combustion engined device. Many engines do not require any fuel pump at all, requiring only gravity to feed fuel from the fuel tank through a line or hose to the engine...
s and hydraulic actuators. The result is better performance at low revolutions per minute
Revolutions per minute
Revolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...
(rpm), lower fuel consumption
Fuel efficiency in transportation
The fuel efficiency in transportation ranges from some hundred kilojoule per kilometre for a bicycle to several megajoule for a helicopter.Efficiency can be expressed in terms of consumption per unit distance per vehicle, consumption per unit distance per passenger or consumption per unit distance...
, and lower harmful emissions.
The engine has crosshead bearings
Bearing (mechanical)
A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...
so that the always vertical piston rod
Piston rod
In a piston engine, a piston rod joins a piston to a connecting rod.Many internal combustion engines, and in particular all current automobile engines, do not have true piston rods, and the term piston rod is often used as a synonym for connecting rod in the context of these engines.All engines...
allows a tight seal under the piston
Piston
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from...
. One of the reasons that the large two-stroke diesels use this design is so that the lubrication
Lubrication
Lubrication is the process, or technique employed to reduce wear of one or both surfaces in close proximity, and moving relative to each another, by interposing a substance called lubricant between the surfaces to carry or to help carry the load between the opposing surfaces. The interposed...
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
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
. 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.
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.
Technical data (as of 2008)
engine configurationEngine configuration
Engine configuration is an engineering term for the layout of the major components of a reciprocating piston internal combustion engine. These components are the cylinders and crankshafts in particular but also, sometimes, the camshaft....
: turbocharged
Turbocharger
A turbocharger, or turbo , from the Greek "τύρβη" is a centrifugal compressor powered by a turbine that is driven by an engine's exhaust gases. Its benefit lies with the compressor increasing the mass of air entering the engine , thereby resulting in greater performance...
two-stroke diesel straight engine
Straight engine
Usually found in four- and six-cylinder configurations, the straight engine, or inline engine is an internal-combustion engine with all cylinders aligned in one row, with no offset...
, 6 to 14 cylinders
cylinder bore: 960 mm
piston stroke: 2500 mm
engine displacement
Engine displacement
Engine displacement is the volume swept by all the pistons inside the cylinders of an internal combustion engine in a single movement from top dead centre to bottom dead centre . It is commonly specified in cubic centimeters , litres , or cubic inches...
: 1820 litres per cylinder
Cylinder (engine)
A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before receiving precision machine work...
engine speed: 92–102 revolutions per minute
Revolutions per minute
Revolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...
torque
Torque
Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....
: 7603850 newton metres (5,608,312 ft·lbf) @ 102 rpm
mean effective pressure
Mean effective pressure
The mean effective pressure is a quantity related to the operation of an reciprocating engine and is a valuable measure of an engine's capacity to do work that is independent of engine displacement. When quoted as an indicated mean effective pressure or imep , it may be thought of as the average...
: 1.96 MPa
Pascal (unit)
The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
@ full load, 1.37 MPa @ maximum efficiency (85% load)
mean piston speed
Mean piston speed
The mean piston speed is the average speed of the piston in a reciprocating engine. It is a function of stroke and RPM. There is a factor of 2 in the equation to account for one stroke to occur in 1/2 of a crank revolution and a '60' to convert seconds from minutes in the RPM term.MPS = 2 *...
: 8.5 metre per second
Metre per second
Metre per second is an SI derived unit of both speed and velocity , defined by distance in metres divided by time in seconds....
specific fuel consumption
Brake specific fuel consumption
Brake Specific Fuel Consumption is a measure of fuel efficiency within a shaft reciprocating engine.It is the rate of fuel consumption divided by the power produced. It may also be thought of as power-specific fuel consumption, for this reason...
: 171 g
Gram
The gram is a metric system unit of mass....
/(kW·h) (126 g/(bhp
Bhp
BHP, or bhp may refer to:*BHP Billiton, Australian based mining company renowned as being the largest mining company in the world**The Broken Hill Proprietary Company Limited, company name 1885-2000**BHP Limited, company name 2000-2001...
·h
Hour
The hour is a unit of measurement of time. In modern usage, an hour comprises 60 minutes, or 3,600 seconds...
), approx. 3.80 litres per second) @ full load; 163 g/(kW·h) (120 g/(bhp·h)) @ maximum efficiency
power
Power (physics)
In physics, power is the rate at which energy is transferred, used, or transformed. For example, the rate at which a light bulb transforms electrical energy into heat and light is measured in watts—the more wattage, the more power, or equivalently the more electrical energy is used per unit...
: 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
Tonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
, 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
Crankshaft
The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...
weight: 300 tons
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.See also
- Forced inductionForced inductionForced induction is the process of compressing air on the intake of an internal combustion engine . A forced induction engine uses a gas compressor to increase the pressure, temperature and density of the air...
- Indirect injectionIndirect injectionIn an internal combustion engine, the term indirect injection refers to a fuel injection where fuel is not directly injected into the combustion chamber...
- Direct injectionDirect injectionDirect injection may refer to:*A music recording technique more commonly referred to as Direct Input*A method of fuel injection for an internal combustion engine, as in a gasoline direct injection petrol engines and most diesel engines...
- TurbochargerTurbochargerA turbocharger, or turbo , from the Greek "τύρβη" is a centrifugal compressor powered by a turbine that is driven by an engine's exhaust gases. Its benefit lies with the compressor increasing the mass of air entering the engine , thereby resulting in greater performance...
- DieselisationDieselisationDieselisation or dieselization is a term generally used for the increasingly common use of diesel fuel in vehicles, as opposed to gasoline or steam engines.-Water Transport:...
- Diesel generatorDiesel generatorA diesel generator is the combination of a diesel engine with an electrical generator to generate electrical energy....
- Napier DelticNapier DelticThe Napier Deltic engine is a British opposed-piston valveless, two-stroke diesel engine used in marine and locomotive applications, designed and produced by Napier & Son...
—a high-speed, lightweight diesel engine used in fast naval craft and some railway locomotives. - History of the internal combustion engineHistory of the internal combustion engineAlthough various forms of internal combustion engines were developed before the 19th century, their use was hindered until the commercial drilling and production of petroleum began in the mid-1850s...
- Hesselman engineHesselman engineThe Hesselman engine is a hybrid between a petrol engine and a Diesel engine introduced by Swedish engineer Jonas Hesselman in 1925. It represented the first use of direct gasoline injection on a spark-ignition engine...