Reciprocating engines in
watercraft propulsion systems
Ph.D. Michał Gajewski | [email protected]| electric-water-mobility.eu
Types of marine propulsions
with reciprocating engines
• Reciprocating engine, generator
and motor are connected to turbine
in series
• A piston engine and electric motors
drive the turbine in parallel
• Electric motors drive the turbine
and are powered by batteries, and
in the event of a discharge they are
powered by generating sets.
• Only the reciprocating engine
drives the turbine (s), a system
with lower efficiency and higher
emissions
G M
ReciprocatingEngine
Electric Generator
Electric Motor
Propeller
Serial turbine drive system
Genset Battery
M
Reciprocating Engine
Electric Motor
Propeller
Parallel turbine drive system
Gearbox
G
Battery
Electric Generator
Serial drive system with an emergency generating setsource: www.weg.net
Advantages of hybrid drives
• Higher efficiency and lower emissions
• Serial and parallel drive can contain several engines instead
of one, which ensures system redundancy
• The electric motor can be additionally powered by renewable
sources
Parallel drive system source: www.weg.net
Principle of operation of a four-stroke engine
Due to the principle of operation, marine reciprocating engines are divided
into spark-ignition and compression-ignition engines. Spark ignition
engines operate in Otto and Atkinson cycles, while compression ignition
engines operate in the diesel cycle. As a result, they differ in the type of fuel
(gas or oil), constructional details, e.g. spark ignition engines contain a
high-voltage spark plug that produces a spark that ignites the fuel mixture.
In addition, there are various degrees of fuel compression.
Otto cycle, source: wikipedia.org
suction stroke compression stroke work stroke exhaust strokestarting position ignition of the mixture
Parameters of piston engines for marine
applications
• Fuel Type (LNG, CNG, petroleum np. biodiesel)
• Engine power 10kW-15000kW• Efficiency >40%• Number of cylinders 3(8)-16• Cylinders positioning (straight or V angle)• Speed of shaft 500-5000 [rev/min]• Work cycle (Otto, 4-stroke)• Compression ratio• Type of cooling (water, air)• Norma emisji spalin (EU Stage V, US Tier IV )
Marine genset 13kW
~1m, 368kg
Marine genset 14800kWsource: cat.com
~17m, 345ton
Cylinder schemesource: wikipedia.org
Crank shaftsource: www.marineinsight.com
Marine engine pistonssource: www.www.engine-spareparts.com
Camshaftsource: www.energyeducation.ca
Basic engine components
• Piston (made of steel or aluminum) (P)
• Crankshaft (C)
• Camshaft, exhaust (E) i suction (I)
• Outlet and inlet valve (V)
• Connecting rod (R)
• Spark plug (S)
• Water cooling jacket (W)
Basic components of engine
• Cylinder liners (wet contact with
cooling water)
• Crankcase (also known as engine body)
• Cylinder head (2 or 4 valves) Engine cylinders wet and dry typesource: www.knowyourparts.com
Crankcase V20source: www.pnp.de
4 valve cylinder headsource: www.ms-motorservice.com
Intercoolersource: www.kelvion.com
Turbocharger for marine enginessource: www.abb.com
Engine components and parts
• Turbocharger (can be two-stage)
• Intercooler (to cool air)
• Gear (driving the camshafts)
• Oil pump (forced lubrication)
• Oil filter
• Cooling water pump
(powered by an electric motor,
in higher power engines there may be two)
• Coupling to the generator
• Air filter
• Vibration damper
• Spring insulators
Throttle valve integrated with the drivesource: www.enserv.de
Gas dosing valvesource: www.woodward.com
Engine controls
• Gas dosing valve (linked to the exhaust gas cleaning system to
control the quality of the mixture)
• Throttle valve (integrated or cooperates with the drive through a set
of control rods)
• Compressor bypass valve
Control system and exhaust
Cooling and heat exchange system
Gas supply system
Crankcase blowing
Lubrication
Auxiliaries supplysystem
Systems enabling the operation of engines
Reciprocating engine
.
G
Generator
Gas inlet
Air
Bypass
Turbocharger
Throttle valve
Speedmeasurement Power
measurement
Electrical energy
Exhaust
Gas dosing valve
x
Generator Circuit
BreakerIgnition control and knocking
sensor
Engine controlsystem
Temperature and pressure measurement
Exhaust emission control and control system
The task of the control system is to control the speed and power of the
engine with simultaneous control of exhaust emissions (carbon and
nitrogen oxides, non-methane hydrocarbons).
Emission limits Stage I to Stage V for HC (hydrocarbons) + Nox (nitrogen oxides) i PM (solid
particles)source: https://theicct.org
Comparing the emission limits PM and NOx between USA and UE
source: https://theicct.org
Exhaust emissions in a gas enginesource: www.sciencedirect.com
Exhaust emissions
control
The exhaust gas emissions depend on
the excess air factor. A suitably high
ratio (lean mixture) ensures that the
requirements for pollutant emissions
are met.
Lubrication systemsource: www.lubrita.com
Oil lubrication system
The task of the engine lubrication
system is to reduce friction, improve
cooling and clean parts under
mechanical and thermal load, such
as: crankshaft and camshafts,
pistons, cylinder liners, gears,
bearings and a turbocharger. In
addition, lubrication, sealing the
combustion chamber,
soundproofing and protection
against corrosion. The main
elements of the lubrication system
are the pump, filter and oil pressure
sensor.
Cylinder coolingsource: www.asecertificationtraining.com
Temperature distribution in enginesource: www.asecertificationtraining.com
Cooling and heat exchange system
The task of the cooling system is to ensure an appropriate operating temperature
between 90-100oC. Too high and too low temperatures can damage engine
components (piston and cylinder). The cooling system consists of an engine block
with cooling channels (so-called water jacket), a water pump, a thermostat, a heater
(heats the water and the engine before starting), a heat exchanger (cooled with sea
water), an expansion tank, a temperature sensor.
Properties of marine engine oil
• Alkaline, protection of pistons and cylinders against acid corrosion
• Oxidation resistance (oil is in contact with air)
• Cleaning properties to maintain metal surfaces of pistons and
cylinders
• High flash point
• Viscosity to ensure lubrication between working parts under load
• Good thermal conductivity
• Low hygroscopicity for water separation
• Low toxicity to the aquatic environment
Shipping oil pack 205 literssource: www.orlenoil.pl
Marine engine oil parameters
• Mineral
• Base number TBN 12 mg KOH/g
• Viscosity grade SAE 30
• Kinematic viscosity
in temperature 1000C 11.3 mm2/s
• Pour point -24oC
• Flash-point 240oC
Oil samples are tested every three months
for the purpose of checking the parameters
determining the degree engine wear.
Influence of glycol content on freezing pointsource: www.kentchemistry.com
Fuel, air and cooling water
A mixture of gas and air is required to burn the fuel in the cylinders. In this
process, gas is the source of energy and air is the source of oxygen. Gas
parameters are determined by the methane number (the equivalent of the
octane number for gasoline), which is an indicator of resistance to knocking
combustion, and by the calorific value.
Cooling water is drinking water withprotective additives againstfreezing (e.g. glycol) and beforecorrosion.
Auxiliary electrical equipment of a
reciprocating engine
• Power supply panel for the engine's electrical equipment with
protection and control elements for the engine and generator
• Power supplies for control, measurement and protection devices
• Spark plugs (12-45kV) with control and power supply systems
• Starter or compressor (electric or pressure starting)
• Heaters for heating water (need to heat the oil)
• Water pump (one or two depending on engine power)
• Low power diesel generator for starting
• Rectifier and battery
• Fans
Structural exposure caused by
torsional vibrations
Torsional vibrations occur from the engine
itself and from the generator. If the frequency
of vibrations is close to the natural frequency,
the vibrations will increase significantly, which
may result in damage to the moving parts of
the engine, cracks in the structure, loosening
and damage to bolt connections, blocking and
damage to the bearings. In order to prevent
this phenomenon, viscous torsional vibration
dampers are used. The viscous muffler
contains a flywheel completely enclosed in the
housing. The spaces between the housing and
the flywheel are filled with silicone oil.
Vibration dampersource: www.geislinger.com
Structural exposure in marine conditions
The rolling of the ship can also fatigue materials
and cause cracks in the structure. Places where
mechanical stresses and places of welded or bolted
connections are at risk. This phenomenon may also
be aggravated by fluctuating temperatures or
weakening of the structure due to corrosion.
Correctness of construction, workmanship and
assembly, corrosion protection and maintenance
play an important role.
In addition to corrosion, high humidity and salinity
may pose a risk of short circuits in electrical and
electronic devices. This is prevented e.g. by
ensuring tightness determined by the IP level.
source: www.gcaptain.com
Reliability of engines
Reliability in marine operating conditions plays a very important role,
therefore for the engine itself and for the entire drive system it is necessary
to provide the best possible reliability indicators and redundancy in case of
failure.
Reliability can be described by parameters:
• Mean Time Between Failures (MTBF)
• Failure rate
• Working time until major renovation
• Number of renovations
• Service life
Diesel engines for hybrid propulsion B33:45Lsource: https://bergen.rolls-royce.com
Engine protection
The protection systems monitor the
operation of the engine through
continuous measurements of
temperature, pressure and oil and
water levels. The exhaust gas
temperature can be measured at the
outlet of each cylinder. When the set
values are exceeded, a warning or a
shutdown may occur depending on
the severity of the event.
Measurements are archived and can
be accessed remotely.Marine propulsion interfacesource: www.freetechnics.eu
Maintenance of reciprocating engines
During operation, marine piston engines require service and systematic
inspections, including on:
• Filling the losses of operating fluids,
• Checking messages from the protection system,
• Assessment of the engine condition by examining the chemical
composition of exhaust gases and pollutants in the oil,
• Replacing air filter inserts,
• Oil and oil filter change,
• Replacing air filter inserts,
• Replacing spark plugs
• Replace gas / fuel filter
HMI interface of the marine gensetsource: www.deif.com
Marine engine-generator interface
The HMI enables the visualization and
control of the operating status and
parameters of generating set. Electrical
parameters such as voltage, frequency,
current and power can be checked.
In addition, operator can start or stop
the engine and start the automatic
synchronization of the generator by
turning on the circuit breaker.
„Color Line” plug-in hybrid ferrysource: www.colorline.com
Batteries parameters: 5MWh, 65ton (working time on batteries 1h, charging time1h)Engine type: diesel V12 Number of engines: 4 Total power of engines: 12680kW
Hybrid powered ferries
Thank you for attention