Reciprocating engines in

watercraft propulsion systems

Ph.D. Michał Gajewski | michal.gajewski@iel.lukasiewicz.gov.pl| 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