For both engine families special attention was drawn during the development phase to the customer related aspects like:
+ Small dimensions
+ Low weight
+ High power to weight ratio
+ Wide performance range
+ Accessories integrated to minimize installation work
+ Reduced life-cycle cost based on
- reduced fuel consumption
- reduced oil consumption
- long TBO's
- extended maintenance intervals
- reduced maintenance work
3. MEGA - STANDARD OF TOMORROW
In 1992 MTU entered into the developing market for large fast ferries with the size of vessels more than 60 meters in length and top speed requirements up to 45 knots.
Fig.6 The 20V1163 and 16V595 engine types were ideally suited to this new market.
More than 120 engines of the 20V1163 type are in service with power settings between 6000 and 6500 kW.
In the power range from 3500 to 3900 kW a number of approx. 50 engines are in operation installed in fast ferries.
High power-to-weight ratio, optimum and compact installation dimensions together with experience gathered from the operation of more than 280 engines of the same series in naval surface vessels in all areas of the western hemisphere have led to this envied market success.
Fig.7 The vessels become bigger and faster. besides diesel engine arrangements, MTU can also provide solutions with so called CODAG-systems that means a combination of diesel engines and gas turbines.
In close discussions with operators and shipyards we have found out that more diesel power is required. As there are limits with the 1163-engien it was decided to develop a new diesel engine family.
The family is named "MEGA" which stands for "Medium speed Engine for General Applications".
The most powerful engine is the 20V MEGA with a power output of 8200 kW at ambient conditions of 45℃/32℃. The rated speed is 1150 rpm.
The engine is equipped with all accessories which are developed and tested together with the basic engine..
In the design is brought in all our experience coming out from the large fast ferry business with the 1163 engine.
Fig.8 gives an impression about the main dimensions of the MEGA where special attention was drawn to get a small width of the engine.
Fig.9 shows a cross section of the new engine. In the following a description of the main components is made:
+ The crankcase has a rigid design and is made out for nodular cast iron with integrated charge air ducting. On top of the crankcase is one centrally located camshaft to drive the valve gear. Large crankcase doors are available for maintenance work and to take care, that also the main bearings can be replaced in situ.
+ The crankshaft is made out of special steel and machined all over with bolted-on counterweights.
+ The power unit comprises the
- cylinder head
- intermediate cooling water housing
- cylinder liner with an anti-polishing ring
The liner with the intermediate cooling water housing is bolted onto the cylinder head and the complete power unit is bolted onto the crankcase.
The design results in the advantages:
+ Low blow-by
+ Extended oil change intervals
+ Low wear on the liners and therefore long maintenance intervals
+ The whole unit is in a very short time replaceable as a single unit
+ The piston is a composite design with a forged steel crown and a steel skirt. The concept is chosen to withstand the high firing pressure and to reduce wear. The piston is oil cooled via spray nozzle and carries two compression rings and one oil control ring.
+ The cylinder head is made out of nodular cast iron and equipped with two inlet and exhaust valves. Integrated are cooled inlet and exhaust valve inserts and valve rotators. These units are replaceable to reduce maintenance cost. Large optimized intake and exhaust channels are responsible for optimized burning process to reduce black smoke, emissions and fuel consumption.
Fig.10 Like the 4000-Series the MEGA is equipped with the common-rail fuel injection system. Two high-pressure pumps are providing a pressure of 1800 bar in the injection system.
The fuel flow goes from the high-pressure pumps to the accumulators which are located on each cylinder head. The volume of the accumulators is of that size, that practically no pressure loss occurs during the injection phase and pressure vibrations can be avoided. The optimized system and max. firing pressure for 230 bar low fuel consumption figures can be reached. The whole injection process is controlled through the electronic engine management system.
Fig.11 The result of the optimization of the whole engine in respect of injection and turbocharging system is shown on the performance map. It is worth noting that the power of 8200 kW can be overloaded by 10% up to 9000 kW. Low fuel consumption figures can be reached over the entire range of the performance map. These figures are valid under fulfillment of the IMO-NOXx-rules. Thanks the sequential turbocharging systems high torque can be provided at low engine speed. Up to an engine speed for 750 rpm the engine can be operated with a double cubic propeller law and is producing a power of more than 4000 kW.
Fig.12 Modern design techniques with the CAD-system "Pro engineer" accompanied with the newest calculation methods and excessive testing on our test benches is the basis in reaching the target "reduction of maintenance work and maintenance costs". The graph shows a comparison of specific costs between our existing engine family 1163 and the new MEGA. The figures are based on an operating profile from a fast ferry.
Fig.13 Special attention was drawn to design a very compact high powered engine. Also for the small engine rooms of catamarans the installation creates no problems. The installation work of the shipyard can be kept on a minimum due to engine installed accessories like:
- Combustion air filters and silencers
- Fuel supply pumps
- Fuel filter
- Lube oil pump
- Automatic lube oil filter
- Lube oil centrifugal filter
- Fresh water and raw water pumps
- Engine sensors, control and monitoring unit