-
s lidi
1-15
h i g h l i g h t s
Exhaust temperature increase by 6.5%, 6.5%, 7reases b4.7%, 1%,
10.5
use computational developed code which uses the results of
combustion and
behavior in Soot and NOx emissions production, it is essential
toemployee an appropriate methodology to reduce the correspond-ing
emissions [1]. Some of the useful technologies to reduce theSoot
and NOx, which have been adopted so far, include high-pres-sure
fuel injection, multiple injections, advancing and retarding
thefuel injection time and using swirl with higher intensity [28].
In
re studied morethe rst aoncept in tamental c
energy availability, which has been introduced in [13]. For aing
the performance of engine subsystems, exergy analysis cuseful
alternative to energy analysis, because it is able tomore
information about engine processes [1416]. Over the years,many
reports have been published on details over the use of thesecond
law of thermodynamics with respect to internal combus-tion engines
[1720]. A summary of other studies on the subjectof DI and IDI
diesel engine was provided below.
Jafarmadar and Zehni [21] carried out a numerical analysisabout
the effect of dwell time duration in a two-stage injection
Corresponding author. Tel.: +98 441 2972000; fax: +98 441
2773591.E-mail address: [email protected] (S.
Jafarmadar).
Fuel 154 (2015) 123131
Contents lists availab
Fue
.ethan other engines due to their higher efciency. Although
NOxand Soot emissions generated in these engines are higher
thanthose of Indirect Injection (IDI) diesel engine, but there are
utilitar-ian technologies to reduce these emissions. Due to
contrasting
tion, the combustion and emission processes athoroughly these
days, implemented by applyingond laws of thermodynamics. Exergy is
the key cond law analysis; that has roots in more
fundhttp://dx.doi.org/10.1016/j.fuel.2015.03.0260016-2361/ 2015
Elsevier Ltd. All rights reserved.nd sec-he sec-oncept,nalyz-an be
arevealLoadIrreversibilityMultidimensional modeling
energy analysis. Various rates and the cumulative exergy
components are identied separately for twoengine cases at various
loads. The comparison of the results show that, as load engine
increases from25% to 100% full load (in 25% increments), the exergy
efciency in air injection engine decreases by5.69%, 10.5%, 10.9%,
and 10.8% in comparison to baseline engine.
2015 Elsevier Ltd. All rights reserved.
1. Introduction
Nowadays, DI diesel engines are being used more frequently
the other method, the amount of Soot and NOx reduced
signi-cantly by adopting air-cell inside piston body [912].
In order to improve engine performance and emissions forma-Air
injectionExergy carried out using an in-ho The accumulative burn
fuel exergy inc The irreversibility increases by 12.8%, 1 The
exergy efciency decreases by 5.69
a r t i c l e i n f o
Article history:Received 31 May 2014Received in revised form 7
February 2015Accepted 12 March 2015Available online 2 April
2015
Keywords:Air-cell.54%, and 7.99%.y 10%, 7.8%, 7.2%, and
8.3%.3.4% and 13.7%.%, 10.9%, and 10.8%.
a b s t r a c t
Research studies indicate that the Soot and NOx emissions in
natural aspirated DI diesel engines, can bereduced through applying
an air jet. In order to achieve this aim, an air-cell can be
designed inside thepiston body by maintaining the performance
parameters. The diameter of the air cell is 35 mm and itsheight is
1.2 mm and the diameter of the throats is 1 mm. At the present
work, however, exergy analysesare carried out for an MT4.244
engine, which is modeled with an air-cell. Energy analyses and
numericalcombustion have been performed for compression ratios of
25%, 50%, 75% and 100% full load. A three-di-mensional CFD code is
employed for this purpose in a closed cycle. The numerical results
of cylinder pres-sure are compared with the measured experimental
data and show a good agreement. Exergy analysis isExergy analysis
of air injection at varioudirect injection diesel engine using
mult
S. Jafarmadar , M. MansouryMechanical Engineering Department,
University of Urmia, Urmia, West Azerbaijan 5756
journal homepage: wwwoads in a natural aspiratedmensional
model
311, Iran
le at ScienceDirect
l
l sevier .com/locate / fuel
-
ry / Fscheme on exergy terms in an IDI diesel engine by
three-dimen-sional modeling. The results show that the results show
that thevalues of work exergy and exergy efciency decrease when
thedwell duration is changed from 5CA to 30CA. Also, there is
asharp change in the exergy parameters when the dwell timereaches
25CA. Jafarmadar and Javani [22] investigated an HCCIengine,
fuelled with the mixture of dimethyl ether (DME) andnatural gas
(NG) in terms of exergy. They showed that when theexcess air ratios
of DME increases at constant air ratio of NG,exergy efciency
increases by 30.2% while irreversibility decreasesby 15.4%.
Moreover, increase in initial temperature brings aboutthe
irreversibility reduction and increases the heat loss exergy.Amjad
et al. [23] used a single-zone model to perform a
numericalavailability analysis for the combustion of n-heptane and
naturalgas blends in Homogenous Charge Compression Ignition
(HCCI)engines. Hosseinzadeh et al. [24] carried out a numerical
studyby comparing the thermal, radical and chemical effects of
EGRgases using a single-zone model to analyze availability in
dual-fuel
Nomenclature
E internal energy (J)G Gibbs function (J)Ex exergy (J)S entropy
(J/K)T temperature (K)kk number of speciesI irreversibility (J/K)y
mass fraction of species
Greek lettersl chemical potential (J/kg)h crank angle (degree)z
number of carbon atom
AbbreviationsBTDC before top dead centerATDC after top dead
centerEVO exhaust valve opening (degree)
124 S. Jafarmadar, M. Mansouengines operated at 50% loads. Turan
[25] studied exergeticinu-ence of some design parameters on the
small turbojet engine forunmanned air vehicle applications.
Jafarmadar [26] studied theeffect of EGR mass fraction on exergy
terms in an indirect injectiondiesel engine. He showed that, as EGR
mass fraction increases from0% to 30% (in 10% increments), exergy
efciency decreases from31.74% to 25.38%. Also, the cumulative
irreversibility related tothe combustion chamber decreases from
29.8% of the injected fuelexergy to 25.5%. Jafarmadar [27] carried
out a numerical exergyanalysis in pre-chamber and main chamber of
an indirect injectiondiesel engine by three-dimensional model. Also
in anotherresearch, Jafarmadar [28] carried out a numerical
analysis aboutthe effect of engine load on the exergy terms of an
(indirect injec-tion) IDI diesel engine by three-dimensional
modeling. Jafarmadaret al. [29] carried out an exergy analysis at
various loads in an IDIlow heat rejection diesel engine by
three-dimensional modeling.They showed that the best operational
load is 75% full load fromsecond law viewpoint.
The study of the relevant literature shows that no attempt
hasbeen done up to now in order to three dimensionally study
theeffects of air injection at various loads on the exergy terms in
DInaturally aspirated diesel engine. In the present numerical
work,the effect of creating an air jet by embedding an air-cell
within pis-ton on combustion parameters in a DI diesel engine has
been stud-ied at various loads from the second law perspective.2.
Initial and boundary conditions
Inlet temperature at 300 K, initial pressure at 1.85 bar,
andengine speed at 2000 rpm are set to be. In-cylinder swirl for
bothbase and modied conditions are considered to be uniform,
theamount of exhaust gas recirculation is assumed to be zero.
Regarding that the analysis is done on the closing cycle,
fromintake valve closure (140 BTDC) to exhaust valve opening
(130ATDC), so the domain of the calculation include the space of
cylin-der, which is divided into head, liner and piston bowl.
Simulationof modied engine condition follows the above-mentioned
pro-cess. In this condition, an air cell and four throats are added
tothe initial geometry. The diameter of the air cell is 35 mm and
itsheight is 1.2 mm. The diameter of the throats is 1 mm. Fig.
1(a)and (b) demonstrates the simulated engines in base and
modiedconditions, respectively. In order to investigate grid
dependency,combustion chamber pressure at 100% load condition for
22,504cells and 56,321 cells is presented in Fig. 1(c). As can be
seen in
CA crank angle (degree)EBU eddy break upID ignition delay(crank
angle)
Subscriptch relating to chemical exergytm relating to
thermo-mechanical exergyf relating to fuelw associated with work
transferQ associated with heat transfer0 dead state, or environment
statepr relating to combustion productsox relating to oxidantsfuel
relating to fuel
Superscript0 restricted dead state
uel 154 (2015) 123131the gure, increasing or decreasing the
number of the cells hasno effect on the results. Boundary
temperatures in the combustionchamber are as follow:
Head temperature: 510 K. Piston temperature: 540 K.
Cylindertemperature: 480 K.
3. Energy analysis
In the present work, AVL Fire U. 8.3 software is used for
numeri-cal simulation of combustion, exhaust emissions, and precise
mod-eling of spraying fuel jet and injecting droplets [30].
Theinvestigated engine is a direct injection diesel engine MT.
4.244made by Motor Sazan Iran company and its specications are
givenin Table 1. In order to explore the effects of air jet, an air
cell isannexed to the main combustion chamber. It should be
mentionedthat compression ratio in both base and modied engines
wereequal. For the 3D simulation, rstly engine cylinder is
modeledby Solid work software. Considering the strategy applied in
AVLFire software for creating meshes, there is a need to create a
sur-face mesh for the model. Thus, the mentioned mesh is created
byfame hybrid assistant tool in AVL Fire software while the
pistonis located in top dead center. Next, complicated 3D
simulation ofengine and creating moving mesh is carried out by
means of fameengine plus tool in AVL Fire. The modeling of the auto
ignition forhydrocarbon fuel is carried out by Shell auto-ignition
model. The
-
ry / FS. Jafarmadar, M. MansouEddy Break-up model (EBU) based on
the turbulent mixing is usedfor modeling of the combustion
process.
During the pre-mixed combustion, due to insufcient air insidethe
main combustion chamber in modied situation, heat releaserate and
combustion pressure for base condition is more than thatfor modied
engine. At diffusion combustion stage, owing to theentrance of
oxygen from air cell into the combustion chamber dur-ing the course
of expansion, the rate of available oxygen at thisstage increases;
combustion occurs more intensely during this per-iod for modied
condition than that for base engine [11].
4. Exergy analysis
The exergy of a system is the maximum amount of work thatcan be
gain from that system when it reaches mechanical, thermal
Fig. 1. Computational geometries for (a) baseline engine, (b)
modied
Table 1Specications of MT4.244DI diesel engine.
Number of cylinders 4-in line, verticalNumber of intake valves 1
per cylinderBore stroke (mm) 100 127Cubic capacity 3.99
lCompression ratio 17.5:1Max power 82 bhp @ 2000 rpmMax toque 360 N
m @ 1300 rpmCombustion system Direct injectionRotation Clockwise,
viewed from frontFuel injection DPA pumpCooling Water cooled with
oil coolerDuration of injection (deg) 20Number of nozzle orice
diameter (mm) 5 0.276Displacement (lit) 3.99Rate of fuel injected
(kg/hr) 15.22Combustion chamber Reentrantuel 154 (2015) 123131
125and chemical equilibrium with its atmosphere. This state of
equi-librium is dened as the dead state of the system and it is
depen-dent on the pressure, temperature and composition of
theatmosphere. According to [3133], the total exergy of a
system(i.e., thermo-mechanical plus chemical exergies) is equal
to:
Ex Exch Extm E P0V T0SXkki1l0i mi 1
where l0i is the chemical potential of species i at the true
dead state,and mi is the mass of species i.
The equation of exergy balance for the inside of the DIengine
chamber, on crank angle basis, is expressed as follows[35]:
dExdh
dExwdh
dExqdh
dIdh
dExfdh
2
Exw denotes the work exergy done by the system and it isdened
as:
dExwdh
P P0dVdh 3
Also, Exq represents the exergy associated with heattransfer
across the chamber boundary. Its variation with crankangle is:
dExqdh
1 T0T
dQdh
4
I is the destruction exergy associated with the combustion
pro-cess and it can be dened as:
dIdh
T0T
Xkki1li
dmidh
5
engine and (c) grid dependency based on the in-cylinder
pressure.
-
where index i includes all the reactants and products. For
perfectgases, li gi.
The exergy of liquid hydrocarbon fuels (CzHy), which are used
incompression ignition engines, is approximated by [34]:
afuel LHV 1:04224 0:011925 yz 0:042
z
;
dExfueldh
afuel dmfueldh6
The exergy efciency can be dened as the ratio of indicatedwork
over total input chemical exergy. For the closed part of thecycle
in an engine, the exergy efciency is dened as:
gII WnetExfuel
7
5. Results and discussion
Calculations are carried out on an MT. 4.244 direct injection
die-sel engine at 25% load, 50% load, 74% load, and 100% load. Fig.
2depicts the comparisons of in-cylinder pressure in the base
engineby experimental results. It is seen that there is a good
agreementbetween the obtained and experimental results. It should
be men-tioned that the peak pressure discrepancy between the
computa-tional and experimental models is less than 4%.
Fig. 3 shows the comparisons of in-cylinder average tempera-ture
for both base and air injection engines at four working modesof the
engines. By decreasing the pressure inside the main chamberat
expansion stroke, the reserved air in the air cell injects into
themain chamber and causes better combustion of the remaining
fuel.By creating air jet, because of increasing of combustion rate
at nal
126 S. Jafarmadar, M. Mansoury / Fuel 154 (2015) 123131Fig. 2.
Comparison of predicted and measured engine in-cylinder pressure
for the base en2000 rpm.gine at (a) 100% load and (b) 75% load, (c)
50% load and (d) 25% load in engine speed
-
S. Jafarmadar, M. Mansoury / Fcombustion stage, the exhaust
temperature from the combustionchamber increases in all four
working modes of the engines. Thisphenomenon is observable in this
Figure. Increases in the exhausttemperature are as follows; 4.2% at
25% load condition, 6.1% at 50%load, 7% at 75% load, and 7.4% at
100% load. Also, the value of peaktemperature in air injection case
is higher than of baseline case at25% load due to more improving of
combustion process in low
Fig. 3. The variation of temperature in cylinder with crank
angle position forbaseline and air injection engines at various
loads and engine speed 2000 rpm.pressure injection. Therefore, the
effect of air injection is con-siderable at lower loads due to
increasing of temperature andimproving of combustion process in
expansion stroke.
Fig. 4. The variation of rate of work exergy with crank angle
position for baselineand air injection engines at various loads and
engine speed 2000 rpm.In Figs. 4 and 5 are shown the development of
both rate andcumulative work exergies in cylinder during for both
base andmodied engines at four working modes of the engines. The
cumu-lative terms are dened after integration of the respective
rateterms over the crank angle engine. At the angles of after start
ofcombustion in various load operations, the rate of work exergy
atbaseline engine increases more than modied engine and
thisincrease is considerable in higher loads due to the lack of
sufcientoxygen inside the main chamber. As shown in Fig. 3, the
pressure
Fig. 5. The variation of accumulative work exergy with crank
angle position forbaseline and air injection engines at various
loads and engine speed 2000 rpm.
uel 154 (2015) 123131 127and temperature gradients in cylinder
at baseline case are higherthan modied case, consequently, higher
rate of work exergy canbe seen at baseline case. By decreasing the
pressure inside themain chamber at expansion stroke, the reserved
air in the air-cellinjects into the main chamber and causes better
combustion ofthe remaining fuel. Therefore, in expansion stroke the
rate of workexergies are the same for two cases. The accumulative
work exer-gies for 25%, 50%, 75% and full load operations are 267,
614, 924,and 1200 J for baseline engine and for modied case are
277,592, 883, and 1160 J, respectively. It can be seen that when
theload increases from 50% to full load, accumulative work
exergyfor modied engine decreases by 3.6%, 4.4%, 3.3%, while in 25%
loadincreases by 3.7% in comparison to baseline engine.
Figs. 6 and 7 respectively show the trends of heat loss
exergyrate and cumulative heat loss exergy in the chamber for two
casesat various loads during the engines closed cycle. At crank
anglesbeyond the start of combustion, the rates of heat loss exergy
forair injection engine is higher than that of the baseline
engine,because during the air injection operation, the combustion
processimproves at expansion stroke due to air injection and higher
oxy-gen availability in the chamber. Also in this case, the heat
loss ofengine walls increases due to high surface of heat transfer.
It isclear from Fig. 6 that when the air cell is created in the
combustionchamber, there are increases in heat loss exergy rate
peak and alsothe rate in expansion stroke in comparison to baseline
case. As isshown in Fig. 7, the accumulative heat losses exergies
for 25%,50%, 75% and full load operations are 54, 85.2, 126, and
172 J forbaseline engine and for modied case are 54.1, 89.9, 133,
and187 J, respectively. These values are 7.2%, 5.7%, 5.7%, and 5.9%
forbaseline engine and for modied case are 6.6%, 5.6%, 5.6% and
-
Fig. 8. The variation of the rate of burn fuel exergy with crank
angle position forbaseline and air injection engines at various
loads and engine speed 2000 rpm.
128 S. Jafarmadar, M. Mansoury / F5.9% of fuel injected exergy,
respectively. It is clear that the per-centage of accumulative heat
loss exergy in air injection enginedecreases due to complete
combustion in expansion stroke andhigher burn fuel exergy. The
value for base line engine is conrmed
Fig. 6. The variation of the rate of heat loss exergy in chamber
with crank angleposition for baseline and air injection engines at
various loads and engine speed2000 rpm.by the work of Primus RJ,
Flynn PF [34] considering heat lossexergy in the diesel engines at
higher engine speed. They showedthat the amount of heat loss exergy
in full load operation andengine speed 1500 rpm is 13.98%. Lower
this value at the presentstudy is due to higher engine speed and
less time for heat transfer.
Figs. 8 and 9 respectively show the variations of rate of
burnedfuel and cumulative burned fuel exergies with crank angle
position
Fig. 7. The variation of the accumulative heat loss exergy in
chamber with crankangle position for baseline and air injection
engines at various loads and enginespeed 2000 rpm.uel 154 (2015)
123131at four working modes of the engines. The process of
combustionin diesel engines includes the stages of ignition delay,
pre-mixedor rapid combustion, diffusion combustion, and late
combustion.Some factors effective in ignition delay are fuel type,
oxygen avail-ability, temperature and combustion chamber pressure.
At pre-mixed stage, the injected fuel during the delayed period
burns ata high rate. Diffusion combustion is associated with the
end ofinjection period, and injection stops at late combustion
stage whilethe fuel is still being mixed inside the chamber by the
gas move-ment; at this stage the rate of combustion basically
depends onoxygen availability and the phenomenon of diffusion. At
25% loadand 50% load, one can observe that ignition delay period
for modi-ed condition is 1 degree less than those for base
condition due tolow oxygen availability. The other reason for this
phenomenon isthat there are higher temperature and pressure in the
modied
Fig. 9. The variation of accumulative burn fuel exergy with
crank angle position forbaseline and air injection engines at
various loads and engine speed 2000 rpm.
-
ry / FS. Jafarmadar, M. Mansoucondition during the ignition
delay period. As can be seen in Fig. 8,at the stage of rapid
combustion at 25% load and 50% load formodied condition, the rate
of burn fuel exergy is higher thanthose for base engine and this is
because of providing optimal con-ditions at the period of ignition
delay (higher temperature andpressure). During the diffusion
combustion, due to insufcient airinside the main combustion chamber
in modied situation, burnfuel exergy rate for base condition is
more than that for modiedengine. At late combustion stage, owing to
the entrance of oxygenfrom air cell into the combustion chamber
during the course ofexpansion after 25 ATDC, the rate of available
oxygen at this stageincreases; combustion occurs more intensely
during this period formodied condition than that for base engine.
At 75% load and 100%load, because of high pressure and temperature
of combustion
Fig. 10. The variation of thermo mechanical exergy with crank
angle position forbaseline and air injection engines at various
loads and engine speed 2000 rpm.
Fig. 11. The variation of chemical exergy with crank angle
position for baseline andair injection engines at various loads and
engine speed 2000 rpm.uel 154 (2015) 123131 129chamber at ignition
delay period, burn fuel exergy rate at pre-mixed stage in base
condition is higher than that in modiedengine. The behavior of burn
fuel exergy rate curve at diffusioncombustion stage is similar to
those at 25% load and 50% load.Also at late combustion stage due to
recirculation of air into themain combustion chamber, more
intensied turbulence occurs inmodied condition than in base engine.
The effect of reserved airjet on main chamber in modied engine is
seen as uctuations inburn fuel exergy rate at late combustion
period. As is shown inFig. 9, the accumulative burn fuel exergies
for 25%, 50%, 75% and
Fig. 12. The variation of total exergy with crank angle position
for baseline and airinjection engines at various loads and engine
speed 2000 rpm.
Fig. 13. The variation of accumulative irreversibility with
crank angle position forbaseline and air injection engines at
various loads and engine speed 2000 rpm.
-
full load operations are 747.4, 1500.9, 2227.5, and 2926.3 J
forbaseline engine and for modied case are 822.2, 1617.6,
2388.1,and 3169.9 J, respectively. It is clear that when the load
increasesfrom 25% to 100%, the percentage of accumulative burn fuel
exergyin air injection engine increases by 10%, 7.8%, 7.2%, and
8.3% due toair injection and complete combustion in expansion
stroke.
Figs. 1012 show the changes of thermo-mechanical, chemicaland
total exergies in the cylinder with crank angle positions fortwo
cases at different loads, respectively. In the compressionstroke,
and before of combustion, the thermo-mechanical exergyin the
chamber increases due to the work produced by the pistonand
increase of the initial temperature associated compressionstroke.
With the start of fuel injection, chemical exergy increasesdue to
increasing of fuel mass fraction and then decrease in thecombustion
period due to the burning of the fuel mixtures. Alsowith the start
of the combustion process, the thermo-mechanicalexergy in the
chamber increases due to the rise of temperature,pressure and the
concentration of complete combustion products.It is clear that the
increase of chemical and thermo-mechanicalexergies with load
operation are considerable at higher loadsbecause of higher fuel
injection higher pressure and temperaturein the cylinder. At the
end of the combustion duration, the amountof chemical exergy
reaches to the minimum value because of thecomplete combustion,
while the thermo-mechanical exergy dimin-ishes due to the decrease
of gas temperature during the expansionstroke. As Fig. 12
illustrates, when the load increases from 25% to100% full load in
air injection case, the exhaust loss total exergiesincreases by
17.8%, 22%, 22.8% and 22.9% in comparison to baselineengine. This
occurs from higher pressure and temperature at theexhaust valve
opening time in the air injection case (as shown inFig. 3).
130 S. Jafarmadar, M. Mansoury / FFig. 14. The variation of (a)
exergy efciency and (b) energy efciency with loadengine.The
combustion process makes the highest contribution to thetotal
in-cylinder irreversibility in a diesel engine, which accordingto
the research by Primus and Flynn [35], is more than 90%. Fig.
13illustrate the trend irreversibility due to in-cylinder
combustionduring an engines closed cycle at two cases in various
loads. Atbaseline engine case, with more oxygen availability, which
resultsin very rapid burning rates (Fig. 9), combustion continue
withhigher rate of temperature variation. Therefore, the rate
ofirreversibility increases more at baseline case than at air
injectioncase particularly in higher loads. It is clear from Fig.
13 that whenair injection is used in expansion stroke and the load
increasesfrom 25% to 100% load, the values of cumulative
irreversibilityincrease by 12.8%, 14.7%, 13.4%, and 13.7% due to
the improvingof combustion and cumulative irreversibility increases
in compar-ison to baseline case.
The variation in the exergy and energy efciencies with
loadengine is shown in Fig. 14 for baseline and air-cell
cases.According to this gure, the values of the exergy and
energyefciencies diminish with load engine at both two cases. Also,
itis evident from the Figure; air injection in each load will
result ina decrease of both rst and second-law efciencies which is
dueto the increase in irreversibility, heat loss, and exhaust
losses.
6. Conclusions
In the present work, a three-dimensionally exergy analysis
wasperformed on an MT4.244 engine under air-injection at
variousloads. The calculated pressures for the base engine are
comparedwith the corresponding experimental data at various loads,
andshow very good agreement. Such correlations between the
experi-mental and computed results make the model reliable for the
pre-diction of exergy terms in air-injection case. Various exergy
termsincluding the fuel, heat loss, irreversibility, work, exhaust
loss,chemical and thermo-mechanical exergies are presented and
com-pared for baseline and air injection cases. The results of the
study,when the load increases from 25% to 100% in 25% steps, are
asfollows:
1. Peak temperatures in cylinder at air injection engine
increaseby 3.22% in 25% load and in others loads decrease by
3.5%,2.6%, and 2.8% in comparison to base engine.
2. Exhaust temperature in cylinder at air injection engine
increaseby 6.5%, 6.5%, 7.54%, and 7.99% in various load
operations,respectively.
3. The accumulative burn fuel exergy in air injection
engineincreases by 10%, 7.8%, 7.2%, and 8.3% in various load
opera-tions, respectively.
4. The cumulative heat loss exergy increases in air
injectionengine by 0.2%, 5.5%, 5.56%, and 8.72% in various load
opera-tions, respectively.
5. Exhaust chemical exergy at air injection engine decreases
by59% in 25% load and increases by 10%, 12.7%, and 23.5% inothers
load operations, respectively.
6. Exhaust thermo-mechanical exergy at air injection
engineincreases by 23.8%, 22.2%, 23.1% and 23.9% in various
loadoperations, respectively.
7. The irreversibility in air injection case increases by 12.8%,
14.7%,13.4% and 13.7% in various load operations, respectively.
8. The exergy efciency in air injection engine decreases by
5.69%,10.5%, 10.9%, and 10.8% in various load operations,
respectively.
References
uel 154 (2015) 123131[1] Okude Keiichi et al. Premixed
compression ignition (PCI) combustion forsimultaneous reduction of
NOx and soot in diesel engine. SAE Trans2004;113(4):100213.
-
[2] Gunabalan A, Tamilporai P, Ramaprabhu R. Effects of
injection timing and EGRon DI diesel engine performance and
emission-using CFD. J Appl Sci(Faisalabad) 2010;10(22):282330.
[3] Jafarmadar S, Zehni A. Multi-dimensional modeling of the
effects of spiltinjection scheme on performance and emissions of
IDI diesel engines. IJE TransC: Aspects 2012;25(2):13546.
[4] Jafarmadar S, Zehni A. Multi-dimensional modeling of the
effects of splitinjection scheme on combustion and emissions of
direct-injection dieselengines at full load state. IJE Trans A:
Basics 2009;22(4):36978.
[5] Flaig, Ulrich, Polach W, Ziegler G. Common rail system
(CR-system) forpassenger car DI diesel engines; experiences with
applications for seriesproduction projects. SAE paper; 1999.
01-0191.
[6] Han Zhiyu et al. Mechanism of soot and NOx emission
reduction usingmultiple-injection in a diesel engine. SAE Trans
1996;105:83752.
[7] Mingfa Y, et al. Experimental study of multiple injections
and coupling effectsof multi-injection and EGR in a HD diesel
engine. SAE technical paper; 2009.01-2807.
[8] Millo F et al. Experimental and computational analysis of
different EGRsystems for a common rail passenger car diesel engine.
SAE Int J Eng2009;2(1):52738.
[9] Nagano S, Hiromitsu K, Katsuyuki O. Reduction of soot
emission by air-jetturbulence in a DI diesel engine. Soc Automotive
Eng 1991.
[10] Choi Cathy Y, Foster DE. In cylinder augmented mixing
through controlledgaseous jet injection. Madison: Diss. University
of Wisconsin; 1995.
[11] Mather DK, Reitz RD. Modeling the use of air-injection for
emissions reductionin a direct-injected diesel engine. Madison:
Diss. University of Wisconsin;1995.
[12] Jafarmadar S, Hosseinzadeh M. Improvement of emissions and
performance byusing of air jet, EGR and insulation methods in a DI
diesel engine. Therm Sci2012;00:29.
[13] Gibbs JW. The scientic papers, vol. 1. New York: Dover;
1961.[14] Dunbar WR, Lior N, Gaggioli RA. The component equations
of energy and
exergy. Trans ASME, J Energy Res Technol 1992;114:7583.[15]
Dunbar WR, Lior N. Sources of combustion irreversibility. Combust
Sci Technol
1994;103:4161.[16] Obert EF. Internal combustion engines and air
pollution. New York: Intext
Educ. Publ.; 1993.
[20] Kyritsis DC, Rakopoulos CD. Parametric study of the
availability balance in aninternal combustion engine cylinder. SAE
paper 2001-01-1263; 2001.
[21] Jafarmadar S, Zehni A. Numerical investigation of the
effects of dwell timeduration in a two-stage injection scheme on
exergy terms in an IDI dieselengine by three-dimensional modeling.
Energy Sci Eng 2014;2(1):113.
[22] Jafarmadar S, Javani N. Exergy analysis of natural gas/DME
combustion inhomogeneous charge compression ignition engines (HCCI)
using zero-dimensional model with detailed chemical kinetics
mechanism. Int J Exergy2014;15(3):36381.
[23] Amjad AK, KhoshbakhiSaray R, Mahmoudi SMS, Rahimi A.
Availability analysisof n-heptane and natural gas blends combustion
in HCCI engines. Energy2011;36(12):69009.
[24] Hosseinzadeh A, KhoshbakhtiSaray R, SeyedMahmoudi SM.
Comparison ofthermal, radical and chemical effects of EGR gases
using availability analysis indual-fuel engines at 50% loads.
Energy Convers Manage 2010;51:23219.
[25] Onder Turan. Exergetic effects of some design parameters on
the smallturbojet engine for unmanned air vehicle application.
Energy2012;46(1):5161.
[26] Jafarmadar S. Multidimensional modeling of the effect of
EGR (exhaust gasrecirculation) mass fraction on exergy terms in an
indirect injection dieselengine. Energy 2014;66(1):30513.
[27] Jafarmadar S. Three-dimensional modeling and exergy
analysis in combustionchamber of an indirect injection diesel
engine. Fuel 2013;107:43947.
[28] Jafarmadar S. Multidimensional modeling of the effect of
engine load onvarious exergy terms in an indirect injection diesel
engine. Int J Exergy2014;15(1).
[29] Jafarmadar S, Tasoujiazar R, Jalilpour B. Exergy analysis
in a low heat rejectionIDI diesel engine by three dimensional
modeling. Int J Energy Res 2013.
http://dx.doi.org/10.1002/er.3100.
[30] AVL FIRE user manual V. 8.5; 2006.[31] Van Gerpen JH,
Shapiro HN. Second-law analysis of diesel engine combustion.
Trans ASME J Eng Gas Turb Power 1990;112:12937.[32] Rakopoulos
CD, Giakoumis EG. Second-law analyses applied to internal
combustion engines operation. Prog Energy Combust Sci
2006;32:247.[33] Ahmadi P, Dincer I, Rosen A. Exergy,
exergoeconomic and environmental
analyses and evolutionary algorithm based multi-objective
optimization ofcombined cycle power plants. Energy
2011;33(10):588698.
[34] Rodriguez L. Calculation of available-energy quantities.
In: Gaggioli RA, editor.Thermodynamics: second law analysis.
Washington DC: American Chemical
S. Jafarmadar, M. Mansoury / Fuel 154 (2015) 123131 131[17]
Rakopoulos CD, Giakoumis EG. Simulation and exergy analysis of
transientdiesel engine operation. Energy 1997;22:87585.
[18] Caton JA. On the destruction of availability (exergy) due
to combustionprocesseswith specic application to internal
combustion engines. Energy2000;25:1097117.
[19] Rakopoulos CD, Andritsakis EC. DI and IDI diesel engines
combustionirreversibility analysis. ASME-WA meeting, New Orleans
LA, Proc. AES, vol.30; 1993. p. 1732.Society Symposium Series No.
122; 1980. p. 3959.[35] Primus RJ, Flynn PF. The assessment of
losses in diesel engines using second
law analysis. ASME WA-Meeting, Anaheim CA, Proc. AES
1986:618.
Exergy analysis of air injection at various loads in a natural
aspirated direct injection diesel engine using multidimensional
model1 Introduction2 Initial and boundary conditions3 Energy
analysis4 Exergy analysis5 Results and discussion6
ConclusionsReferences