With the advent of technology, the maritime industry is changing every day. Each and every shipowner wants to make maximum profit with minimum investment. One such investment is expenditure on fuel oil on ships. The majority of fuel oil is consumed by the Main Engine.
The OEMs(e.g.- MAN B&W, Wartsila Sulzer, Mitsubishi, etc.) are trying their level best to make their engines more efficient than earlier.
Efficiency= Output/Input
The Efficiency can be increased in the following ways:-
- Increasing Output
- Reducing Input
- Reducing Losses
OEMs have come up with Intelligent engines which are camless. Lesser moving parts reduce friction leading to reduced Frictional Horse Power(FHP). Wartsila has come up with RT-Flex series of Engines, whereas MAN has come up with ME series engines.
Both the series function differently. As a user, it’s important for us to know the advantages and shortcomings of each engines. Let’s appreciate the companies for their efforts and advancements instead of simply declaring the winner. So, what are you waiting for? Let’s go!
RT-Flex Engines:-
Manufacturer:- Wartsila Sulzer
Advantages:-
- Computerized control increases flexibility and reliability in Engine operation.
- Absence of cams, camshaft, gears, push-rod, etc gives advantage in a better power to weight ratio, due to weight reduction.
- Single nozzle Injection is of great advantage to operator. At low load operation by further reduction in engine rpm and thus increases the manoeuvrability of vessel.
- Inculcating single nozzle Injection reduces smoke during Manoeuvring.
- Sequential operation is used to prevent localised heat concentration and avoid unequal expansion of combustion chamber components.
- Sequential operation in this case can be utilised for step injection to be able to get lower peak pressures for a longer period and contribute to less NOx formation. However this can be done without step injection too.
- Common Rail Fuel Injection system has a common fuel rail maintained at 1000 bar irrespective of engine loading. This helps in good injection even at low loads.
- Fuel Quality Setting and Variable Injection Timing helps in achieving fuel economy by varying the injection timing according to engine loading and fuel quality.
- Variable Exhaust Valve Opening/Closing helps in increasing Engine Flexibility by way of varying power output , and actuate the exhaust valve keeping in mind the compression ratio, firing ratio, etc.
- Less moving parts
- Greater Redundancy(compared to RTA)
Shortcomings:-
- Problems during Maintenance:- Requires delicate handling of sensors and instrumentation system ensuring probable re-calibration of measuring equipments. No. of working parts are reduced and maintenance is only for piston and liners.
- Additional measures need to be adopted to mitigate danger from high pressure (Fuel oil-1000 bar and servo oil- 200 bar). (Safeguard against careless workmanship)
- Sound knowledge of fault identification in micro controller system to be able to identify and replace the faulty cards.
ME Engines:-
Manufacturer:- MAN
Advantages:-
- Removal of mechanical actuating parts like cams, camshafts, etc. improves power to weight ratio.
- Cylinder Control Unit(CCU) changes the actuation and timing of valves considering the individual cylinder conditions. This makes cylinder control more independent.
- Alpha Lubrication proves to be very efficient in facing the arduous conditions during Cylinder Lubrication.
- Work on maintenance of actuators , fuel boosters still remain.
- Lesser moving parts contribute towards reduced FHP.
- FIVA valve accurately controls timing and duration of fuel injection.
- Opening and Closing of Exhaust valve can be changed considering the cylinder conditions.
- Electronic Control improves flexibility in Engine Operation
Short-Comings:-
- No provision for sequential injection.
- Fuel Injection System can be improvised to give better performance in low-load condition or during starting.
Both Series engines have their own ways to perform the same thing. These were some points about ME and RT-Flex engines.
Did we miss any point? Please let us know in the comments.
Authored By:- Cdt. Abhishek Kumar Ojha, TMI
