This document provides an overview of different types of marine diesel engines categorized by speed:
- Low speed engines (LSE) operate between 55-150 rpm, are usually large bore 2-stroke cycle engines with a direct drive to the propeller. Manufacturers include MAN-B&W and Sulzer-Wartsila.
- Medium speed engines (MSE) mostly operate on the 4-stroke cycle between 150-600 rpm. They are smaller than LSEs and often use reduction gearing. They are commonly used as auxiliary engines.
- High speed engines (HSE) operate above 400-1000+ rpm and are rarely used except as emergency generators. They use higher speed diesel and cannot run
2. Comparative Study: These can be grouped
under: Low Speed Engines (LSE) 55-150rpm
Medium Speed Eng (MSE) 150-600
High Speed Engines (HSE) 400-1000+
NOTE: All marine Engines are Diesel Engines.
Petrol/Gasolene engines are NOT
permitted on board.
3. Low Speed Engines (LSE) - These are
usually:
i) Large bore (big dia cyl & piston)
ii) 2-Stroke cycle.
iii) Crosshead Construction.
iv) Have direct drive to propeller.
v) Crank & Cyl spaces are separate.
4. LSE : a) Tolerate low quality fuels and burn
these satisfactorily to give highest thermal
efficiencies.
b) Slow piston speed reduces wear , reduces
Lube oil consumption and gives high
reliability. Suited for ocean going large ships.
c) Stroke to bore ratio vary from 1.2 to 4.7 with
low speeds up to 55rpm.
d) Manufacturers: MAN-B&W, Sulzer-Wartsila,
Mitsubishi.
10. MSE : Medium Speed Engines:-
a) Most operate on the 4-Stroke Cycle.
b) They are of ‘Trunk Piston’ construction.
c) Smaller & lighter than the slow speed 2-St engines
d) The bigger sized MSE are used for propulsion.
e) Require reduction gearing to get lower propeller rpm.
f) Mostly used as aux engines for electricity generation.
g) May be ‘In-line’ or in “V-Form” construction.
15. HSE…High Speed Engines: 1000+ rpm.
a) Rarely used on board except in some cases
as Aux Diesels & Emergency Gen.
b) Operate on the 4-st principle with VGT.
c) Fuel used is High Speed Diesel (HSD)
d) HSE are used in small vessels with/without
reduction gears.
e) HSE cannot be run on Residual fuels.
16. USES:
LSE: Main Propulsion engines for ships. They can
burn low quality fuels. Power plants also use
them for power generation on shore.
MSE: auxiliary engines for power generation on
ships. Also used for propulsion with gear box.
Used for power generation on shore.
HSE: Emergency generators/compressors. Life
boats, High speed boats.
17. • Manufacturers of 4-St Engines:
• i)Sulzer, MAN, Wartsila, B & W, Daihatsu,
Mitsubishi,Caterpillar, Pielstic, Akasaka,Deutz.
• ii) Rolls-Royce Group: Allen, Berger , AMS,
Bandoin, Callesan.
• Deere, Detroit Diesels, Electromotive,
Hanshin, Hedemora, Isuzu,
Iveco,Kelvin,Lugger, Makita, Mitsui, MTU,
Nigaata……..and many more.
18. MICE-I : Practical Heat Balance diagram
• THE DE has high thermal efficiency and low fuel
consumption as compared to any other form of
engine or prime mover.
• The Heat Balance of an internal Comb Engine
indicates the heat rejected to:
i) Jacket Cooling Water, ii) Turbocharger jackets,
iii) Lubricating oil, iv) after cooling exhaust (boiler),
iv) radiation, v) heat energy to provide power, vi) air
cooling, vii) loss to atmos.
19. MICE-I : Practical Heat Balance
diagram
Figure shows a typical Heat Balance fo a modern
high output (356x457mm) T/C diesel engine
based on Specific Fuel Consumption (SFC) of
226gms/KWhr. With fuel oil heat value
42.6MJ/Kg.
Any Heat Balance Diagram must co-relate with
Engine performance, fuel consumption, and
calorific value of the fuel used.
23. Marine I C Engines…Mean Piston
Speed.
The MPS 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.
For example, a piston in an engine which has a stroke of
90 mm will have a mean speed at 3000 rpm of 2 * (90
/ 1000) * 3000 / 60 = 9 m/s.
MPS play an important role in exchange of gases. Beyond
a certain piston speed the efficiency of the gas
exchange process drops sharply there by resulting in
poor combustion.
24. MICE-I : Mean Piston Speed
The mean piston speed is a parameter in the power
equation which suggests that power can simply be
Increased by increasing the MPS
• Increase in MPS will increase the dynamic forces and
moments and this will affect bearings, bearing bolts,
and the moving components.
• If MPS is high, time available for fuel combustion is
less. Complete burning of the fuel is poor.
• If MPS is low, compression will be isothermal but we
want compression to be adiabatic. Low MPS will cause
compression temperature to be low resulting in
incomplete combustion and increase in fuel
consumption.
• Speed decreases service life of frictional parts.
25. MICE-I : MCR & CSR
MCR: ‘Maximum Continuous Rating’ - It is the
maximum power output engine can produce
while running continuously at safe limits and
conditions. It is specified: Eg at 100%load - MCR
speed= 105 rpm and MCR power= 14380kw
the engine nameplate and in the Technical File of
the marine diesel engine. MCR speed is at
100%load and is run during sea trials or an
emergency situation. Its fuel efficiency is less in
this case but it can run safely at this speed
continuously.
26. MICE-I : MCR & CSR
CSR: Continuous Service Rating (also known as
NCR-Normal Continuous Rating).
it is the output power at normal service speed
corresponding to economical efficiency
,thermal efficiency , mechanical efficiency and
easy maintenance.
It is at this speed the company recommends the
ship to run . At this speed all the parameters
are normal and engine efficiency is at its peak.
27. MICE- I…Thermal Efficiency
A typical diesel automotive engine operates at around
35% to 40% of thermal efficiency. About 65-70% is
rejected as waste heat without being converted into
useful work, i.e. work delivered to output shaft.
In short: Thermal efficiency= Work done
Energy input
It is impossible for heat engines to achieve 100%
thermal efficiency () according to the Second law of
thermodynamics. ... This is impossible because some
waste heat is always produced in a heat engine.
