177
1
INTRODUCTION
Themarinedieselengineisthemainpropulsionofthe
ship due to high efficiency, power and reliability.
Also, it is the main source of harmful emissions, so
shipownersandenginemanufacturers areforcedto
find new solutions for reducing pollutants in the
combustion process. The emission regulations
required
by International Maritime Organization
(IMO), especially for NO
X and SOX pollutants, are
more stringent with each new amendment andthey
presentagreaterchallengeforshipowners.Oneofthe
methods for reducing emissions in exhaust gases is
the modification of the combustion process in the
engine.Thismethodincludesoptimizationofthefuel
injection with adequate injection timing (split
injection,
earlyandlateinjection)andoptimizationof
exhaust and inlet valve closing/opening timing.
Emissionreductionwithsplitinjectionispresentedin
article [1], where authors simulated split injection
with the Miller cycle with exhaust gas recirculation.
StratsianisV.,etal.inresearch[2]concludedthatwith
injection strategies (post‐injection) on
a marine
engine,thereductionofemissionscouldbeachieved,
howeverintermsofNO
Xemissionsthisreductionis
farfrommeetingIMONO
XTierIIIRegulation.
The pre‐injection strategy with different pre‐
injectiontimingandmassratioisexplainedinarticle
[3], which provided a better understanding of the
combustionprocessandthephenomenonofknockin
thecylinder.Nemati A., etal. [4]conducteda study
on the influence of pilot
fuel injection timing on
combustion process and emissions formation. The
technicalconditionofthe mainengineis also highly
importantfortheefficiencyofthecombustionprocess
andthepercentageofpollutantsinexhaustgases.The
fuel pump fault (leakage) and delay of fuel pump
Impact of Late and Early Fuel Injection on Main Engine
Efficiency and Exhaust Gas Emissions
Z.Pavin,V.Knežević,J.Orović&M.Valčić
UniversityofZadar,Zadar,Croatia
ABSTRACT:Exhaustgasemissionsfromshipsareanaspectoftheglobalmaritimeindustrywhichhasbeen
given great importance in recent years. Increasing the efficiency of maritime transport regarding fuel
consumption and exhaust gas emissions is an ongoing effort which requires a detailed analysis of
all ship
systemsthathaveaneffectontheaforementionedissue.Oneaspectthatcanbeanalyzedinthisregardarethe
variousmachineryfaultswhichinfluencetheshipsexploitationefficiency.Thispaperwillfocusontheanalysis
ofthetwostrokeslowspeeddieselmainenginewithearlyand
latefuelinjectionfaults.Thisanalysisisbased
on a set of data acquired from a simulation model of a LCCtanker vessel including fuel consumption and
emission pollutants such as carbon monoxide (CO), sulphur oxides (SO
X) and carbon dioxide (CO2) as a
greenhousegaswithearlyandlatefuelinjectionfaultintroducedtodifferentnumberofmainenginecylinders.
This methodology of research has the advantage of analyzing various scenarios which are not as easily
reproducedonactualvessels.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 17
Number 1
March 2023
DOI:10.12716/1001.17.01.19
178
injectionby5°ofcrankshaftanglearesimulatedinthe
article [5]. The results have revealed the changes in
specific fuel consumption (SFC), the increase of
exhaust temperature and the reduction of fuel
injection pressure. Other articles [6, 7] provided
insightintothefaultsoftheturbochargersystemand
its
effects on the main engine. The exhaust
temperaturewillincreasewiththefoulingofturbine
wheel or blockage of the air filter, which will
consequently affect the exhaust emissions. The
adequatemaintenanceoffuelsystemcomponentsand
optimizationoffuelinjectioniscrucialforanefficient
combustionprocess.
2
METHODOLOGY
The data used for the research in this paper was
obtained on the Wärtsilä ERS‐LCHS 5000 TechSim
engine room simulator, owned by the Maritime
departmentoftheUniversityofZadar.Themodelled
vesselisaLCCtankerwithaMANB&W6S60MC‐C,
two strokes, slow speed, turbocharged, reversible
main diesel engine [8]. The vessel simulated in this
modelisshowninfigure1.
Figure1.Simulatormodelvessel‐LCCtankerwithaMAN
B&W6S60MC‐Cmainengine[8]
Thedieselengine,typeMC,isatwo‐strokediesel
engine with direct injection and centrally located
exhaust valve. MAN Diesel & Turbo is one of the
worldʹs leading designers and manufacturers of
engineswithlowandmediumspeed.Enginetrialtest
report,the so‐calledshop test report,MAN
6S60MC
wasusedduringtheanalysisofoperatingparameters
andrecordingtheindicatordiagramoftheenginein
real conditions [9]. These data were compared with
data obtained on the ship simulator ERS 5000
TechSim. Obtained values for: mean effective
pressure,maximumcombustionpressure,fuelpump
index recordedin the
trial test were compared with
shipsimulatorinnormalconditionsataspeedof105
min‐1andtheyarealmostidentical.Therefore,itcan
beconcludedthattheshipsimulatorisvalidforthis
research [9]. The basic main engine particulars are
shownintable1.
Someofthemany
featuresofthesimulatormodel
are introducing various environmental and fault
variables during vessel navigation such as
environmental loads, late and early fuel injection,
pistonringwear, damagedfuelnozzle,turbocharger
airfilterblockageetc.Thefaultsusedfortheresearch
inthispaperarelatefuelinjection,earlyfuel
injection
andturbochargerairfilterblockage.Thelimitationsof
using simulated data for scientific research is the
possible inaccuracy of the mathematical model used
for simulator programming. This can only be
validatedusingdatafromonboardmeasurementson
actualvessels.
Table1.Mainengineparticulars[8]
________________________________________________
MainEngineParticulars
________________________________________________
TypeMANB&Wmodel6S60MC‐C
Ratedpower 13736kW
Cylindernumber 6
Bore600mm
Stroke2400mm
Ratedspeed 105Rpm
NominalMCR 13736kWat105RPM
________________________________________________
Area of navigation chosen for the simulations is
theAdriaticSea, however since environmental loads
i.e., wind, waves, wave spectrum and sea current,
werenotsimulatedforthepurposesof thisresearch
theareaofnavigationisoflittleimportanceandofno
impact.Fuel used for the combustion process in
the
main engines is a distillate marine diesel oil (MDO)
withlessthan0.5%ofsulphurcontent.Thesimulated
parametersrecordedforthepurposeofthisresearch
were average cylinder exhaust gas temperature
shown in degrees Celsius (°C), main engine fuel oil
consumption (FOC) shown in litres per hour
(L/h),
carbon dioxide emission (CO
2) shown in percentage
by volume (%), sulphur oxides emission (SO
X) and
carbon monoxide emission (CO) shown in parts per
million (ppm). The degree of late or early injection
timingwaschosenbasedonexperienceinthisfieldof
researchandwassetatvaluesexpressedinnegative
orpositivedegreesofcrankshaftposition(°)relative
toitspositionatnormal
injectiontiming[0(allcyl)]as
is shown in table 2. the degree chosen was the
maximumpossiblesettinginthesimulatormodeland
is thus only expressed in later text with respective
abbreviations ‘EI’for early injection and‘LI’ for late
injection.Earlyandlatefuelinjectionfaultparameters
were introduced in three stages at specific time
intervals chosen to give the parameters recorded
enoughtimetostabilizeatarelativelyconstantvalue.
Thefirststagewasearlyorlatefuelinjectiononone
cylinder[EIorLI(1cyl)],thesecondstagewasearly
or late fuel injection on
three cylinders [EI or LI (3
cyl)] and the third stage was early or late fuel
injections in all cylinders [EI or LI (all cyl)]. The
turbocharger air filter blockage fault parameter was
introduced in four stages at specific time intervals
same as the early and late fuel injection fault
parameter.Thefourstageswere10%,20%,30%and
40%turbochargerairfilterblockageshownintable2.
Theobservedtimeneededforparameterstabilization
was two minutes. All of the above‐mentioned
parameters were simulated under one engine load
setting. The engine load simulated is 85
% of
maximum continuous rate (MCR). This engine load
waschosenbasedonusualoptimumengineloadfor
the specific engine type used in the referent vessel
[8,10].
Table2.Injectiontimingandairfilterblockagedegree
relativetospecificsimulationtimeintervals
________________________________________________
T(min)0:00 2:00 4:00 6:00 8:00
________________________________________________
InjectionTiming0 EI EI EI /
(Early)(allcyl) (1cyl) (3cyl) (allcyl)
Injectiontiming0 LI LI LI /
(Late)(allcyl)(1cyl)(3cyl) (allcyl)
Turbocharger 0 10 20 30 40
AirFilter
Blockage
________________________________________________
179
3
RESULTSANDDISCUSSION
The goalof this research is totest whether injection
timing has any significant impact on exhaust gas
emissionandtocompareittoanotherpotentialmain
enginefault,inthecaseofthispaper,turbochargerair
filterblockage.Theresultsoftheresearchareshown
through several
different parameters (average
cylinderexhausttemperature,CO/SO
X/CO2emission,
fuel oil consumption). The data accumulated in the
lateinjectionfaultsimulationisshownintable3.
Table3.Effectoflateinjectiontiming(LI)onspecific
parameters
________________________________________________
InjectionEGCyl CO SOX CO2 FOC
timing Avg[°C] [ppm] [ppm] [%] [L/h]
________________________________________________
0(allcyl) 258.50 82.50 28.60 4.49 2142.95
LI(cyl1)262.51 82.50 28.60 4.49 2159.47
LI(cyl1,2,3) 274.33 83.51 28.60 4.49 2209.84
LI(allcyl) 293.64 84.51 28.60 4.49 2292.79
________________________________________________
In the late injection simulation average cylinder
exhaust gas temperature, CO, SO
X, CO2, and FOC
parameters increase, or decrease, was analyzed with
respect to their reference values at the normal
injectiontiming(0allcyl)forallcylinders.Whilethere
isnosignificanteffectshowninthethreeexhaustgas
compound emissions there is an increase in both
average cylinder exhaust gas temperature
and main
engine fuel consumption. Average cylinder exhaust
temperatureincreaseswitheveryadditionalcylinder
lateinjectionfaultandisshowninfigure2.However,
amoreimportanteffectcouldbetheslightincreasein
mainenginefuelconsumptionwhichisalsopresentat
every additional late injection fault as is
shown in
figure3.
After observing the two afore mentioned
parameters it can be concluded that the increase in
averagecylinderexhausttemperatureisproportional
totheincreaseofmainenginefuelconsumption.
Figure2.Averagecylinderexhausttemperaturevs.injection
timinginthelateinjectionscenario
Figure3.Fueloilconsumption(FOC)vs.injectiontimingin
thelateinjectionscenario
The second simulated scenario is opposite to the
first,i.e.,earlyinjectionsimulatedforzero,onethree
and all cylinders. The data accumulated in this
simulationisshownintable4.
Table4.Effectsofearlyinjectiontiming(EI)onspecific
parameters
________________________________________________
InjectionEGCyl CO SOX CO2 FOC
timing Avg[°C] [ppm] [ppm] [%] [L/h]
________________________________________________
0(allcyl) 258.50 82.50 28.60 4.49 2149.95
EI(cyl1)253.63 82.48 28.60 4.49 2115.48
EI(cyl1,2,3) 246.66 82.48 28.60 4.49 2086.93
EI(allcyl) 236.77 80.59 28.60 4.49 2048.66
________________________________________________
The parameters are, as before, compared to their
respectivereferencevaluesatnormalinjectiontiming
for all cylinders (0 all cyl). Again, there is no
significant effect on direct exhaust emissions.
However,areverselyproportionaleffectcanbeseen
on exhaust gas temperature and main engine fuel
consumption when compared to
the late injection
simulation parameters. The decrease in exhaust gas
temperatureseemstobeproportionaltothedecrease
in main engine fuel consumption as can be seen in
figures4and5.
Figure4.Averagecylinderexhausttemperaturevs.injection
timingintheearlyinjectionscenario
180
Figure5.Fueloilconsumption(FOC)vs.injectiontimingin
theearlyinjectionscenario
Thethirdandlast simulated scenariowasthatof
another main engine fault, more precisely
turbocharger air filter blockage. The purpose of this
wastocomparetheemissionandotherparametersof
the first two simulated scenarios to a different
situation where there might be a more significant
impacton several
or all tested parameters.The data
accumulatedduringthissimulationisshownintable
5.
Table5.Effectsofturbochargerairfilterblockageonspecific
parameters
________________________________________________
Airfilter EGCyl CO SOX CO2 FOC
blockage[%] Avg[°C] [ppm] [ppm] [%] [L/h]
________________________________________________
0 258.50 82.50 28.60 4.49 2142.95
10 274.17 92.57 31.08 4.75 2134.77
20 292.42 101.61 33.53 4.75 2137.33
30 353.41 106.60 38.95 5.62 2157.90
40 286.34 64.02 31.70 4.76 917.95
________________________________________________
The parameters in this simulation are as well
comparedtotheirrespectivereferencevaluesatzero
percent(0)turbochargerairfilterblockage.Inthecase
of carbon monoxide, sulphur oxide and carbon
dioxidedirectemissionsthereisasignificantincrease
inallthreeco mpoundsasisshowninfigures6and
7.
Figure6. CO, SOX concentration vs. turbocharger air filter
blockageintheairfilterblockagescenario
Figure7. CO2 concentration vs. turbocharger air filter
blockageintheairfilterblockagescenario
Thedecrease shown at40 %airfilter blockageis
due to the main engine going into slow down and
therefore the average cylinder exhaust temperature
and main engine fuel consumption also decrease in
thisstep ofthesimulationprocess.Averagecylinder
exhaust temperature, shown in figure 8, displays a
constant
increasefrom0%to30%airfilterblockage.
Main engine fuel consumption slightly decreases
whengoingfrom 0%to10 %airfilterblockagebut
latersteadilyincreasesduringthestepsfrom10%to
20%andfrom20%to30%airfilerblockage.Main
enginefuelconsumptionisshowninfigure9.
Figure8. Average cylinder exhaust temperature vs.
turbocharger air filter blockage in the air filter blockage
scenario
Figure9. Fuel oil consumption (FOC) vs. turbocharger air
filterblockageintheairfilterblockagescenario
The large difference this specific fault displays
when compared to the first two simulations is the
increase in direct measured exhaust gas component
emissions.
181
4
CONCLUSIONS
Theresultsofthisresearchwereeffectiveatproving
thatearlyandlatefuelinjectioninaslowspeedtwo
strokedieselenginehaslittletonoeffectonincreased
direct exhaust gas emissions. The results of
introducing early and late injection fault were
compared with the turbocharger air filter
blockage
faulttopresentthesimulatedmodelwherethereisa
significant effect on direct exhaust gas emission
manifested in the increase of emitted harmful and
greenhouse compounds. However, it can be argued
that the increase in main engine fuel consumption
with the late fuel injection condition could lead to
overall increased exhaust gas emissions on specific
voyages.Consideringthattheprevalentfuelsusedin
maritimetransportationarestillfossilfuelsthisleads
toincreasedgreenhousegasandpollutantemissions.
The results have shown that energy efficiency is,
therefore,impactedbythedegreeoflatefuelinjection.
The improved propulsion efficiency
and reduced
dailyfuelconsumptioncouldbeachievedbyplanned
maintenanceandfaultdiagnosticswhentakingearly
and late fuel injection into consideration. Moreover,
the optimal frequency of main engine component
maintenance could be selected depending on
differences in the afore mentioned parameters. The
datainthisresearchcanbe
usedtofurtheranalyzethe
maritimevesselexploitationeconomyandtoimprove
mainenginemaintenancestrategies.
REFERENCES
[1]Imperato, M., Kaario, O., Larmi, M. et al. Emission
reduction methods and split fuel injection in a marine
four‐strokeengine.JMarSciTechnol23,94–103(2018).
https://doi.org/10.1007/s00773‐017‐0458‐6
[2]Stratsianis,V.,etal.,EffectsofFuelPost‐Injectiononthe
PerformanceandPollutantEmissionsofaLargeMarine
Engine, Journal of Energy Engineering 142(2), DOI:
10.1061/(ASCE)EY.1943‐7897.0000337
[3]Huaiyu Wang, Huibing Gan, Gerasimos
Theotokatos,;Parametricinvestigationofpre‐injectionon
thecombustion,knockingandemissionsbehaviourofa
largemarinefour‐strokedual‐fuelengine,Fuel,Volume
281, 2020,118744, ISSN 0016‐2361,
https://doi.org/10.1016/j.fuel.2020.118744.
[4]Nemati,A.,Ong,
J.C.,Pang,K.M.,Mayer,S.,&Walther,
J.H.(2022).Anumericalstudyoftheinfluenceofpilot
fuel injection timing on combustion and emission
formationundertwo ‐strokedual‐fuelmarineengine‐like
conditions. Fuel, 312,
https://doi.org/10.1016/j.fuel.2021.122651
[5]Lewinska, J. The influence of fuel injection pump
malfunctions of
a marine 4‐stroke Diesel engine on
composition of exhaust gases. Combustion Engines.
2016,167(4),53‐57.doi:10.19206/CE‐2016‐405
[6]Anantharaman, M.; Khan, F.; Garaniya, V.; Lewarn, B.
Reliability Assessment of Main Engine Subsystems
Considering Turbocharger Failure as a Case Study,
TransNav2018,12,271–276
[7]Knežević V,
Orović J, Stazić L,Čulin J. Fault Tree
AnalysisandFailureDiagnosisofMarineDieselEngine
Turbocharger System. Journal of Marine Science and
Engineering. 2020; 8(12):1004.
https://doi.org/10.3390/jmse8121004
[8]ERS5000TechSimMANB&W6S60MC‐CDieselEngine
– Tanker LCC (Aframax) Trainee Manual, November
2014,WärtsiläVoyageLimited.
[9]Vukičevi
ć M. et. al., Analysis of the Influence of
Preventive Maintenance of Main Engines on Working
Parameters and Emissions, Fifth conference
ˇMaintetnance2018”,Zenica,10.May2018.
[10]MAN B&W S60MC‐C8‐TII Project guide‐Camshaft
ControlledTwo‐strokeEngines,1stEdition,MANDiesel
&Turbo,Augsburg,Germany,2010.
