comparative evaluation of combustion, performance, and emissions of jatropha

1565r 2010 American Chemical Society pubs.acs.org/EF

Energy Fuels 2010, 24, 1565–1572 : DOI:10.1021/ef901194zPublished on Web 01/07/2010

Comparative Evaluation of Combustion, Performance, and Emissions of Jatropha

Methyl Ester and Karanj Methyl Ester in a Direct Injection Diesel Engine

S. Jindal,*,† Bhagwati P. Nandwana,† and Narendra S. Rathore‡

†Mechanical EngineeringDeptt, ‡Renewable Energy SourcesDeptt, College of Technology andEngineering, Udaipur 313001 India

Received October 20, 2009. Revised Manuscript Received December 12, 2009

Biodiesel prepared from different vegetable oils and fats are likely to have some comparative advantagesand disadvantages. Two major oil varieties, considered suitable for biodiesel making are Jatropha curcasand Pongamia pinnata. This study targets at making a comparison of the methyl esters of these oils in adiesel engine against diesel fuel. The performances of the fuels was evaluated in terms of thermal efficiency,specific fuel consumption, power output and mean effective pressure, cylinder pressure, rate of pressurerise, and heat release rates. The emissions of carbon monoxide (CO), carbon dioxide (CO2), unburnthydrocarbon (HC), oxides of nitrogen (NOx), and smoke opacity with the three fuels were also compared.Both varieties of the oil, after transesterification, exhibit the major properties within acceptable limits ofbiodiesel standards set by many countries. Karanj methyl ester (KME) performed better than jatrophamethyl ester (JME), whereas the shortest ignition delay is observed with JME. Both the esters performedpoorer than diesel, but emissions of HC, NOx, and smoke were found to be lower with esters. The threefuels delivered almost the same brake power, even when the indicated power was higher with diesel.

1. Introduction

Fuels of bio-origin provide a feasible solution to the twincrises of “fossil fuel depletion” and “environmental degrada-tion” by substituting the petroleum fuels used in internalcombustion engines. The fuels of bio-origin may be alcohol,vegetable oils, biomass, and biogas. Some of these fuels can beused directly whereas others need to be formulated to bringthe relevant properties close to conventional fuels.

A significant research effort has been directed toward usingvegetable oils and their derivatives as fuels for diesel engines.Nonedible vegetable oils in their natural form, called straightvegetable oils (SVO); methyl or ethyl esters known as treatedvegetable oils; and esterified vegetable oils, referred to asbiodiesel, fall in the category of bio fuels. There exists anumber of vegetables/plants that produce oil and hydrocar-bon substances as a part of their natural metabolism. Thesevegetable oils fromoil seeds crops such as soybean, sunflower,groundnut mustard, etc. and oil seed from tree origin have90-95% of the energy value of diesel on a volume basis,comparable cetanenumber, and canbe substituted 20-100%.

Biodiesel is considered a promising alternative fuel for usein diesel engines, boilers, and other combustion equipment.Compared to fossil diesel fuel, biodiesel has several superiorcombustion characteristics. The fuel characteristics of bio-diesel are approximately the same as those of fossil diesel fueland thus may be directly used as a fuel for diesel engineswithout any modification of the design or equipment. Inaddition, these are biodegradable, can be mixed with dieselin any ratio, and are free from sulfur.

Although biodiesel has many advantages over diesel fuel,there are several problems that need to be addressed, suchas its lower calorific value, higher flash point, higher visco-sity, poor cold flow properties, poor oxidative stability, and

sometimes its comparatively higher emission of nitrogenoxides.1 Biodiesel obtained from some feed stocks mightproduce slightly more oxides of nitrogen (1-6%), which isan ozone depressor, than that of fossil origin fuels but can bemanaged with the utilization of blended fuel of biodiesel andhigh speed diesel fuel.2 It has been reported that the lowerconcentrations of biodiesel blends improve the thermal effi-ciency. Reduction in emission and brake-specific fuel con-sumption is also observed while using B10.3 Most of theresearch studies concluded that a 20% blend of biodiesel withdiesel works well in the existing design of engine and para-meters at which engines are operating.3

Biodieselmade fromdifferent feed stockshave been tried bymany, and the effect of feedstock on engine performance andemissions are well documented. Jatropha and karanj are thetwo major feed stocks that are object of research in India.Jatropha curcas, locally known as ratanjyot, belongs to thefamily of Euphorbiaceae. It is a quick yielding plant thatsurvives in degraded, barren, forest land and draft-proneareas and is cultivated as a hedge on the farm boundaries(Figure 1). The deoiled cake is excellent organic manure thatretains soil moisture. This oil is gaining popularity due to itsgood properties and has been accepted and recommended byNational Biodiesel Board of India4 as a source of alternativefuel for blending in the commercial diesel. Karanj (Pongamiapinnata) is an underutilized plant that is grown in many partsof India (Figure 2). Sometimes the oil contains high free fattyacids (FFAs) depending upon themoisture content in the seed

*Towhom correspondence should be addressed. Telephone:þ91 2942490664. Fax: þ91 294 2420196. E-mail: [email protected].

(1) Lin, C.-Y.; Lin, H.-A. Fuel 2006, 85, 298–305.(2) Yohaness, F. Fuelling a Small Capacity Agricultural Unmodified

Diesel Engine With Macroemulsified Ethanol, Diesel and JatrophaDerived Biodiesel: Performance & Emission Studies. M.E. Thesis,Mechanical Engg Deptt, Delhi College of Engg, Delhi, 2003.

(3) Ramadhas, A. S.; Muraleedharan, C.; Jayaraj, S. Renew. Energy2005, 30, 1789–1800.

(4) Report of the committee on development of biofuel, Planning com-mission, Government of India, 2003.

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Energy Fuels 2010, 24, 1565–1572 : DOI:10.1021/ef901194z Jindal et al.

during collection. It is a fast growing leguminous tree with thepotential for high oil seed production and the added benefit ofan ability to grow onmarginal land. These properties supportthe suitability of this plant for large-scale vegetable oil pro-duction needed for a sustainable biodiesel industry. Thepotential of jatropha oil5-7 and karanj oil8-10 as a source offuel for the biodiesel industry is well recognized. The impor-tant characteristics of these oils are given in Table 1, and fattyacid composition is given in Table 2.

Looking to the availability and their biodiesel potential,these oils are becomingmore andmore popular inmany othercountries as well. Evaluation of jatropha esters11 and karanjesters12 indicates their superiority over many other vegetableoils in termsof engineperformance, emissions, ease of use, andavailability. All of the studies made so far with these oils wereindependently done in different types of engines in differentconditions. An effort is made in this study to compare thecombustion, engine performance, and emissions with themethyl esters of these oils in one engine, keeping all otherconditions same, for establishing the suitability of these estersagainst diesel fuel.

2. Experiment and Procedure

In the study, the selected two vegetable oils were transesteri-fied and the effect onmajorpropertieswas evaluated. Further,the evaluation of the two methyl esters was done in acompression ignition engine for combustion, performance,and emissions. The results were compared against the dieselfuel results.

Transesterification. The transesterification of these oilsamples was carried out in the lab using standard proceduresadopted commonly through out the world.13 As jatropha oilcontains low FFA (less than 5%), methanol with KOH ascatalyst was used. For karanj oil (FFA more than 5%), theFFAwas reduced first by acid-catalyzed esterification (usingmethanol in presence of sulphuric acid) and then alkali-catalyzed esterification (using methanol in presence ofKOH) was done. After separation of glycerol, the ester waswater washed to remove unreacted methoxide. It was thenheated to remove the water traces to obtain clear biodiesel.The methyl ester (biodiesel) thus produced by this processwas totally miscible with mineral diesel in any proportion.

The properties of so prepared biodiesel were tested in thelaboratory using standard test procedures as per ASTM/BISand are listed in Table 3. The properties tested were relativedensity (standard RD bottles of 50 mL capacity), calorificvalue (adiabatic bomb calorimeter), kinematic viscosity(Redwood No.1 viscometer), flash point (Pensky-Martenclosed cup apparatus), cloud and pour points, free fatty acidcontents (chemical titrationmethod), and iodine value (usingWij’s solution).

Experimental Setup. The study was carried out in thelaboratory on an advanced fully computerized experimentalengine test rig comprised of a single cylinder, water cooled,naturally aspirated, four-stroke diesel engine, commonlyused in agriculture sector for minor irrigation needs, con-nected to an eddy current type dynamometer for loading.The setup (Figure 3) includes necessary instruments foronline measurement of cylinder pressure, injection pressure,and crank-angle. One piezo sensor is mounted on the enginehead through a sleeve and the other is mounted on the fuelline near the injector for measurement of pressures. Thesetup has transmitters for air and fuel flow measurements,process indicator, and engine indicator. Rotameters areprovided for cooling water and calorimeter water flowmeasurement. Provision is also made for online measure-ment of temperature of exhaust, cooling water, and calori-meter water inlet and outlet and load on the engine. Thesesignals are interfaced to a computer through a data acquisi-tion system, and the software displays the P-θ and P-Vdiagrams.Windows-based engine performance analysis soft-ware package “Enginesoft LV” is used for on-line perfor-mance evaluation. The setup enables study of engineperformance for power, mean effective pressure, thermalefficiency, specific fuel consumption, air-fuel (A/F) ratio,and heat balance. The specifications of the engine and detailsof instrumentation are given in Tables 4 and 5, respectively.

Emission Measurement. The exhaust gases were sampledfrom the exhaust line through a specially designed arrange-ment for diverting the exhaust to a sampling line withoutincreasing the back pressure and was then analyzed using a

Figure 1. Plant, fruit, and seed of Jatropha curcas.

Figure 2. Tree, fruit, and seed of karanj.

(5) Berchmans, H. J.; Hirata, S. Bioresour. Technol. 2008, 99, 1716–1721.(6) Ramesh, D.; Sampathrajan, A. Investigations on Performance

and Emission Characteristics of Diesel Engine With Jatropha Biodieseland Its Blends. Agricultural Engineering International: the CIGREJournal. Manuscript EE 07 013. Vol. X. March, 2008.(7) Pramanik, K. Renew. Energy 2003, 28, 239–248.(8) Srivastava, P. K.; Verma, M. Fuel 2007, doi:10.1016/j.

fuel.2007.08.018.(9) Sharma, Y. C.; Singh, B. Fuel 2007, doi:10.1016/j.fuel.2007.08.001.(10) Karmee, S. K.; Chadha, A. Bioresour. Technol. 2005, 96, 1425–

1429.(11) Agarwal, D.; Agarwal, A. K. Applied Thermal Eng. 2007, 27,

2314–2323.(12) Agarwal, A. K.; Rajamanoharan, K. Applied Energy 2009, 86,

106–112.

(13) Van Gerpen, J.; Shanks, B.; Pruszko, R.; Clements, D.; Knothe,G. Biodiesel Production Technology. Subcontractor report prepared underNational Renewable Energy Laboratory, CO; available electronically athttp://www.osti.gov/bridge.

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portable multigas analyzer (make- MRUAirfare, Germany;model-DELTA1600S). Itmeasures carbonmonoxide (CO),carbon dioxide (CO2), hydrocarbons (HC), and nitric oxide(NOx). For the measurement of smoke intensity (percentopacity HSU) of the diesel engine’s exhaust, a diesel smokemeter (model- DSM 2000; make- Manatec Electronics) wasused. The measurement range and accuracy of instrumentused are given in Table 6.

Experimental Procedure. Initially, the engine was run onno load condition and its speed was adjusted to 1600 ( 10rpm. The engine was then tested at no load and at 25, 50, 75,100 and 125% loads. As per the test rig specifications, atrated power, that is, at full load (100%), the eddy currentdynamometer is to be loaded with 12 kg load for a given armlength. The engine at the above-mentioned loads was testedon all three of the fuel types. For each load condition, theengine was run for at least 3 min, after which data werecollected. The experiment was replicated three times. For allsettings, the emission values were recorded thrice and ameanof these was taken for comparison. The performance ofthe engine at different loads and settings was evaluated interms of brake thermal efficiency (BTHE), brake specific fuelconsumption (BSFC), indicated (IP) and brake power (BP),

exhaust temperature, indicated mean effective pressure(IMEP), cylinder pressure (pc), rate of pressure rise (dp/dθ),net heat release rate (dQn/dθ) and emissions of carbonmonoxide (CO), carbon dioxide (CO2), unburnt hydrocar-bon (HC), and oxides of nitrogen (NOx) with exhaust gasopacity. The software enables evaluation of performancefrom the acquired data using standard relationships. TheBTHE is evaluated using the expression BTHE = (BP �3600 � 100/volumetric fuel flow in 1 h � fuel density �calorific value of fuel). Similarly, BSFC is evaluated on thebasis of fuel flow and BP developed by the engine using theexpression BSFC= (volumetric fuel flow in 1 h � fuel den-sity/BP). The indicated work done per cylinder per cycle(area of indicator diagram � scale factor � 105) and the IP[indicated work done per cycle� speed/(2� 10-3)] are com-puted from the area of indicator diagram.

The indicated mean effective pressure is a measure of theindicated work output per unit swept volume, in a form inde-pendent of the size and number of cylinders in the engine andengine speed and is computed as (IMEP = indicated workoutput/swept volume). The rate of pressure rise (Δpc* =Δpc � Vi/Vc) and net heat release rate (dQn/dθ = (γ/(γ -1))p(dV/dθ) þ (1/(γ - 1))V(dp/dθ)) are computed using thecylinder pressure history (p - θ).14

3. Results and Discussion

The effect of transesterification on major properties of theoil is given in Table 3. The relationships between independentvariables (fuel and load) anddependent variables are shown inthe figures, and the results are discussed in the following sec-tions. Summary of analysis of variance is provided in Table 7.

Effect of Transesterification. It is observed that the densityof karanj oil is higher than jatropha oil in raw form, whereasafter transesterification it reduces to a value lower than that

Table 1. Characteristics of Jatropha and Karanja

1 english name jatropha karanj2 botanical name Jatropha curcas Pongamia pinnata3 distribution/ climate throughout India excluding

temperate region, farm boundaries,waste land, alongside railway track

throughout India excluding temperateregion, road side, railway track

4 promising states Rajasthan, Andhra Pradesh, Chhattisgarh,Jharkhand, Karnataka, Madhaya Pradesh,Maharashtra, Uttar Pradesh, and West Bengal

Andhra Pradesh, Chhattisgarh, Jharkhand,Karnataka, Madhaya Pradesh, Maharashtra,Uttar Pradesh, and West Bengal

5 morphology short plant (shrub) with big leafs and amplespreading, Quite hardy, drought resistant andtolerate to salinity

medium size with a short bole and spreadingcrown, quite hardy, drought resistant andtolerate to salinity

6 propagation seed, cuttings seed7 collection period Winter May-June8 sowing time July-August June-August9 gestation period 2 years (max) 4-6 years10 yield potential

(a) seed 2.5-5 t/ha 5-8 t/ha(b) oil 0.9 - 1.6 t/ha 1.5-2.4 t/ha

11 contents(a) oil 28-30% (seed) ; 50-60% (kernel) 27-39% (kernel)(b) protein 18% 30-40%

12 uses(a) oil biodiesel, soap, industrial biodiesel, soap, industrial(b) cake organic manure organic manure

13 density 0.92 g/cm3 0.92 g/cm3

14 acid value <3.0 mg KOH/g 5.06 mg KOH/g15 saponification value 185-210 KOH/g 187 KOH/g16 iodine value 95-110 86.5 g17 unsaponifiable matter <1.0 % w/w 2.6 % w/w

a Source: Compilation from http://www.svlele.com.

Table 2. Fatty Acid Composition of Karanj and Jatropha Oilsa

percentage (%)

fatty acid structureb formula karanj oil jatropha oil

palmitic acid 16:0 C16H32O2 3.7-7.9 13.6-15.1stearic acid 18:0 C18H36O2 2.4-8.9 7.1-7.4oleic acid 18:1 C18H34O2 44.5-71.3 34.3-44.7linoleic acid 18:2 C18H32O2 10.8-18.3 31.4-43.2lignoceric 24:0 C24H48O2 1.1-3.5 0.2archidic 2.2-4.7 0.2-0.3behenic 4.2-5.3 0.2eicosenoic 9.5-12.4

a Source: Compilation from http://www.svlele.com. b XX:Y=No. ofcarbon atoms: No. of double bonds.

(14) Stone, R. Introduction to Internal Combustion Engines, Secondrevised edition; Macmillan: Palgrave, 1992.

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of the jatropha oil ester. When compared with diesel, therelative density of raw oils is found to be higher by about8-10%, whereas after esterification the value is higher onlyby 4-5%. The reduction is likely due to substitution ofglycerides with alcohol during transesterification process.

Reduction in heating value of about 1-3% is observed ontransesterification of these oils. Jatropha oil possess about7.88% less heat content, whereas karanj oil shows a deficit of10.4% as compared to the heating value of diesel.

The kinematic viscosity of vegetable oils is very high ascompared to diesel at ambient temperature, but significantreduction is obtained by transesterification. The viscosity (at32 �C) of jatropha oil, drops from 46.8 cSt to 8.3 cSt ontransesterification, whereas karanj oil’s viscosity drops from46.3 cSt to 6.5 cSt. These viscosities are still higher than thatof the diesel (3.93 cSt at 32 �C). The temperature of oil has a

remarkable effect on the viscosity as also seen in many otherstudies.15 At 60 �C, the viscosities are in close range with thatof diesel and are within prescribed limits of 2.0-7.5 cSt forHSD (IS:1460-1974).

As reported in literature, the cloud point and pour pointof diesel are<3 �C and<-5 �C, respectively. The vegetable

Table 3. Evaluated Properties of Oils and Their Methyl Esters

jatropha karanj

property unit biodiesel BIS std diesel oil methyl ester oil methyl ester

density gm/cm3 0.87-0.90 0.8394 0.9187 0.8838 0.9317 0.8749calorific value MJ/kg 44.13 40.65 39.40 39.54 39.19kinematic viscosity

at 32 �C cSt 3.5-5.0 3.93 46.8 10.8 46.03 7.52at 60 �C cSt 2.77 23 5.82 18.3 3.2

cloud point �C <3 4 0 9 2pour point �C r5 1 -3 6 -2flash point �C >100 56 210 118 226 122FFA % <0.8 5.01 0.28 10.73 0.50iodine value <115 98.91 100.01 78.44 82.66

Figure 3. Test Engine setup.

Table 4. Test Engine Details

item details

make Kirloskarmodel TV1details single cylinder, DI, four strokecooling waterbore and stroke 87.5 mm � 110 mmcubic capacity 0.661 Lcompression ratio 17.5:1rated power 3.5 kW at 1500 rpmload at rated power 12 kginjector opening pressure 210 barpeak pressure 77.5 kg/cm2

injection timing 23� BTDC static (diesel)modified compression ratio range 12-18

Table 5. Instrumentation Details

instrumentation make/model/specs

dynamometer eddy current type- model AG10of Saj Test Plant Pvt Ltd.

cylinder pressure sensor piezo sensor of PCBPiezotronics Inc., model- M111A22;resolution- 0.1 psi; sensitivity- 1 mV/psi

fuel pressure sensor piezo sensor of PCB Piezotronics Inc.,model- M108A02; resolution- 0.4 psi;sensitivity- 0.5 mV/psi

load measurement load cell -Sensortronics make,model 60001 with digital indicator,range 0-50 kg, supply 230 VAC

fuel flow measurement differential pressure transmitter,make- Yokogawa;model- EJA110A-DMS5A-92NN

air flow transmitter make- Wika; model- SL1temperature sensor type RTD, PT100 and thermocouple, type Ktemperature transmitter type two wire, input RTD PT100,

range 0-100 �C, output 4-20 mA andtype 2 wire, input thermocouple,range 0-1200 �C, output 4-20 mA

crank angle sensor digital encoder- resolution 1�,speed 5500 rpm with TDC pulse

calorimeter type- pipe in pipeengine indicator input: piezo sensor(cylinder pressure

and injection pressure), crank angle sensor,No. of channels 2, communication RS232

software “Enginesoft LV” engine performanceanalysis software (on NI platform)

(15) Abramovic, H.;Klofutar, C.ActaChimSlov. 1998, 45(1), 69-77.

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oils exhibit higher values for these, but significant lowering isseen on transesterification. With these values of cloud pointand pour points, both the oils are suitable for use in mostparts of our country around the year.

Flash point (closed cup) values for these oils are signifi-cantly affected by the transesterification, which lowers theflash point temperature by almost 50% for both the oils.Although, higher flash point poses problems in self-ignitionin CI engines, but looking to the safe storage and handling ofthese biodiesels, almost all standards laid out for biodieselindicate a required value of more than 100 �C. This standardalso eliminates the possibility of untreated methanol con-taminating the biodiesel. The flash points of both, JME andKME, meet the standards (Table 3).

The FFA contents of oils vary depending upon the sourceof oil, its exposure to air, etc. The FFA contents usuallyincrease on holding the oil for long duration in contact withair. Free fatty acid contents of karanj oil sample are found tobe very high (up to 10%) as compared to jatropha (up to 5%)putting up difficulty in transesterification, hence two stageesterification is needed for karanj oil. By transesterification,it can be brought within permissible limits of less than 0.8%.The FFA contents of JME and KME are 0.3 and 0.5%,respectively. Iodine value (IV) of the oils remains littleaffected by transesterification. This is because of the factthat the process is not affecting the degree of unsaturation ofthese oils. The IV of both oils is well within the permissiblelimits (<115).

Brake Thermal Efficiency. The brake thermal efficiencyof an engine increases significantly with load up to therated load as lesser losses are encountered at higher loads.The effect of load on BTHE is expressed as second orderpolynomials for all the fuels (BTHED = -0.1703(load)2 þ4.1445(load) þ 1.6602 with R2 = 0.991; BTHEJME =-0.1233(load)2 þ 3.2763(load) þ 1.3802 with R2 = 0.996;and BTHEKME = -0.1517(load)2 þ 3.7217(load) þ 1.5807with R2 = 0.9979). The brake thermal efficiency obtainedwith diesel was higher than that obtained by both of biodiesel(Figure 4). KME gave consistently higher BTHE than JMEover entire load range. The viscosity of KME is lower thanthat of JME and hence better combustion takes place, whichis also indicated by comparatively higher exhaust tempera-ture and lower BSFC. At full load, the BTHE values fordiesel, JME and KME were found to be 26.49, 22.69, and24.03%, respectively. The smaller differences in BTHE atlower loads tend to increase with increase in load. Jhala16

observed 21.85% thermal efficiency with JME. Kumar17

observed 4.13% lower thermal efficiency with karanj ethylester as compared to diesel. Raheman and Phadatare18 also

observed decrease in thermal efficiency for B100 while usingkaranj ester. Murillo et al.19 tested pure and blends ofbiodiesel in a marine engine and found lower thermal effi-ciency with all as compared to diesel fuel.

Brake Specific Fuel Consumption. The BSFC decreaseswith load significantly for all the fuels as the power out-put per unit fuel consumption decreases at higher loads.Second-order polynomials relate this decrease (BSFCD =0.0034(load)2 - 0.0799(load) þ 0.7461 with R2 = 0.9906;BSFCJME = 0.0038(load)2-0.0968(load)þ0.9981 with R2=0.9988; and BSFCKME = 0.0033(load)2 - 0.0787(load) þ0.7921 with R2=0.9634).

The brake-specific fuel consumption with diesel fuellingwas lower than that for the other two fuels as shown inFigure 4. The BSFC values for diesel, JME, andKME at fullloadwere 0.29, 0.39, and 0.34 kg/kWh, respectively. It is seenthat the difference between BSFC of diesel and biodiesel islarger at lower loads as compared to full load. This is due tothe fact that the esters of vegetable oils have lower heat valuewhen compared to diesel and therefore more biodiesel isneeded to maintain the power output. Similar findings arereported by other researchers also.3,20-22 The BSFC forKME is lower as compared to JME as the relative densityof KME is lower than that of JME and hence lesser mass ofKME fuel is injected in the same volume. Jhala16 alsoobserved 4.65% higher BSFC while testing the engine per-formance with JME, and Kumar17 reported 15% higherBSFC with karanj ethyl ester. Raheman and Phadatare18

reported an increase in BSFC up to 11-48% for B100 whileusing karanj ester. Canacki and Van Gerpen23 observed13.5% higher specific fuel consumption for neat soybeanmethyl ester.

Power and Mean Effective Pressure. With the increase inload on the engine, the indicated power and mean effectivepressure increases linearly with load. The relation shipsbetween load and indicated power are linear (IPD = 0.7094-(load) þ 1.8402 with R2 = 0.9975; IPJME = 0.715(load) þ1.4783 with R2=0.9972; and IPKME=0.7392(load)þ 1.4484with R2 = 0.999).

The indicated power developed by the engine with dieselfuel is also found to be higher than that of the biodiesel(Figure 5) similar to the results of indicated mean effectivepressure development. The indicated power developed withKME is slightly higher than that developed by JME above50% load. At full load, JME and KME developed 5.09 and5.19 kW, respectively, whereas diesel developed 5.41 kW ofindicated power, i.e., losses of 6 and 4% respectively withesters. Lin et al.24 also observed a 3.5% loss of power withpure palm oil biodiesel. The mean effective pressures at fullload for diesel, JME, and KME are 6.49, 6.09, and 6.17 barrespectively. The mean effective pressure with JME is lowerby 6.2%, and with KME a loss of 5% is observed.

Table 6. Measurement Range and Accuracy of Delta 1600S Gas

Analyser

measured gases measuring range accuracy

HC 0-20,000 ppm (30 ppmCO 0-10% (0.2%CO2 0-16% (1%NOx 0-5000 ppm (10 ppm

(16) Jhala, K. B. Influence of Jatropha ester blends on the perfor-mance and emission characteristics ofCI engines. Ph.D.Thesis,MaharanaPratap University of Agriculture and Technology, India, 2006.(17) Kumar, S. Use of ethyl ester of Karanja (pongamia glabra) oil as

a fuel for diesel engine. M.E. Thesis, Maharana Pratap University ofAgriculture and Technology, India, 2004.(18) Raheman, H.; Phadatare, A. G. Biomass Bioenergy 2004, 27,

393-397.

(19) Murillo, S.;M�ıguez, J. L.; Porteiro, J.; Granada, E.;Moran, J. C.Fuel 2007, 86, 1765–1771.

(20) Puhan, S.; Vedaraman, N.; Sankaranarayanan, G.; Ram, B. V.B. Renew. Energy 2005, 30, 1269–1278.

(21) Sahoo, P. K.; Das, L.M.; Babu,M.K. G.; Naik, S. N. Fuel 2007,86, 448–454.

(22) Ozkan, M.; Ergenc, A. T.; Deniz, O. Turkish J. Eng. Env. Sci2005, 29, 89–94.

(23) Canakci, M.; Van Gerpen, J. H. Comparison of engine perfor-mance and emissions for petroleum diesel fuel, yellow grease biodiesel,and soybean oil biodiesel. ASAE Annual International Meeting, 2001;016050

(24) Lin, Y. C.; Lee, W.; Hou, H. Atmos. Environ. 2006, 40, 3930–3940.

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Brake power of the engine is almost the same (little higher)for all fuels indicatingbettermechanical efficiencywith esters asfrictional losses are lower due to higher lubricity of these fuels.

Exhaust Temperature.Temperature of exhaust gases, leav-ing the cylinder, represents the extent of temperature reached inthe cylinder during combustion. With increasing load, the cy-linder pressure increases and more of the fuel is burnt, leadingto an increase in temperature. The relationships are best ex-pressedas second-orderpolynomials (ExTD=8.1518(load)2þ6.68(load)þ179.2 with R2=0.9972; ExTJME=7.3547(load)2þ9.444(load)þ146.68 with R2=0.9991; and ExTKME=7.4932-(load)2 þ 8.5113(load) þ 160.84 with R2=0.9999).

At standard values of engine parameters, the temperatureof exhaust gases is observed to be higher with B0 as com-pared to B100 for entire load range (Figure 4). This isexpected as the heat contents of B0 are more than B100and greater amount of heat is released in combustion cham-ber leading to higher temperature. Also, the heat released bycombustion of diesel is late by a few degrees and thus moreheat gets exhausted. The temperature of exhaust gasesobtained with JME were lowest, followed by KME. Thetemperature of exhaust at full load for JME, KME, anddiesel was 383, 393, and 427 �C respectively.

Rate of Pressure Rise and Net Heat Release Rate. Thepressure in the cylinder during the cycle is found to be almostthe same for both methyl esters and diesel. The rate of

pressure rise for full load is found to be highest with dieselfuel as compared to other fuels, but the biodiesel fuels;JMEand KME;shifts the peak pressure rise rate toward the topdead center (TDC) with reduced ignition delay. The peakrate of pressure rise with diesel, JME and KME were foundas 4.79, 4.02, and 3.82 bar/CA (bar per crank angle),respectively. KME advances the peak pressure rise rateposition more (4�) as compared to JME (2�) because of itshigher volatility. The ignition delay is shortest with JME (5�)followed byKME (7�) and diesel (8�). The shift is mainly dueto advancement of injection due to higher viscosity andearlier combustion due to higher cetane number of thesefuels (Figure 6).

Similarly, the peak net rate of heat release (NHR) is lowerfor JME (42.14 J/CA) and KME (39.86 J/CA) as comparedto diesel (53.95 J/CA), but earlier heat release is obtainedwith biodiesel. The double peak shape of the heat releaseprofile is characteristic of diesel combustion. The first peakoccurs during the premixed combustion phase and resultsfrom the rapid combustion of the portion of the injected fuelthat has vaporized and mixed with the air during the delayperiod, and the second peak occurs duringmixing controlledcombustion which depends on injection duration.25 It is

Table 7. Analysis of Variance Summarya

variables BSFC BTHE ex temp IMEP IP HC CO NOx CO2 opacity

Mean Effect between Fuelsfuel (D v/s JME & KME) * * * * * * * * NS *

Mean Effect between Loadsload (0, 3, 6, 9, 12, 15) * * * * * NR NR NR NR NR

a *, significant at 0.05 level; NS, non significant; NR, no reading.

Figure 4. BTHE, BSFC, and exhaust temperature vs load. Figure 5. IMEP, indicated and brake power vs load.

(25) Ferguson, C. R.; Kirkpatrick, A. T. Internal Combustion En-gines, Applied Thermosciences, Second ed.; John Wiley: New York, 2001.

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observed that 10% of fuel burned earlier for biodiesel,whereas 90% of fuel burned earlier for diesel, showing fasterburn rate and higher rate of pressure rise at a later crankangle position.26

Emissions. The emission parameters for different fuelsmeasured at full load are shown in Figure 7 and 8. Theunburnt hydrocarbon emission (UHC) is highest for diesel(Figure 7). With JME and KME as fuel, UHC emissions arereduced by 56 and 40%, respectively. Reductions in UHCemissions up to 75%have been recordedbyLast et al.27whileusing biodiesel from soybean oil, and Krahl et al.28 reported50% reduction with rapeseed biodiesel. The reasons forreduction in UHC as reviewed by Lapuerta et al.29 are:higher oxygen content (leading to more complete combus-tion), higher cetane number (reducing combustion delay),higher final distillation point for diesel (final fraction maynot vaporize), and advanced injection and combustiontiming.

The smoke opacity of engine exhaust (Figure 8) is lower by20%with JMEand by 41%withKMEas compared to dieselexhaust. Jhala16 reported 14.55% reduction in smoke opa-city with JME. Krahl et al.30 reported a maximum reduction

of particulate matter up to 40% using rapeseed oil biodiesel.The reason for reduction in smoke opacity (or particulatematter) is again higher oxygen contents of the biodieselmolecule, which enables more complete combustion evenin regions of the combustion chamber with fuel-rich diffu-sion flame promoting the oxidation of the already formedsoot.31

The measured values of NOx emissions with JME andKME are lower than that with diesel (Figure 8). With JMEthe reduction is 25%, whereas with KME the reduction is48%. At full load JME and KME emitted 178 and 147 ppmof NOx against 237 ppm with diesel. The decrease in NOx

emissions with biodiesel has also been reported by many

Figure 6. Cylinder pressure, rate of pressure rise, and net heatrelease rate at full load. Figure 7. Emissions of UHC, CO, and CO2 at full load.

Figure 8. Emissions of unburnt NOx and smoke at full load.

(26) Sinha, S.; Agarwal,A.K.Combustion characteristics of rice branoil derived biodiesel in a transportation diesel engine. SAE paper No.2005-26-356.(27) Last, , R. J.; Kruger, , M.; Durnholz, , M. Emissions and

performance characteristics of a 4-stroke, direct injected diesel enginefueled with blends of biodiesel and low sulfur diesel fuel. SAE paperNo.950054, 1995.(28) Krahl, J.; Munack, A.; Schroder, O.; Stein, H.; Bunger, J.

Influence of biodiesel and different designed diesel fuels on the exhaustgas emissions and health effects. SAE paper No. 2003-01-3199.(29) Lapuerta, M.; Armas, O.; Fernandez, J. R. Prog. Energy Com-

bust. Sci. 2008, 34, 198-223.(30) Krahl, , J.;Munack, , A.; Bahadir, ,M.; Schumacher, , L.; Elser, ,

N. Review: utilization of rapeseed oil, rapeseed oil methyl ester or dieselfuel: exhaust gas emissions and estimation of environmental effects.SAE paper No. 962096, 1996.

(31) Graboski,M. S.;McCormick, R. L.Diesel Engines. Prog. EnergyCombust. Sci. 1998, 24, 125-164

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others. Jhala16 reported 8.69% lower emission with JME.Graboski et al.32 indicated a linear relationship betweenNOx

emission and iodine number of the fuel being tested. As theiodine value of KME is lower than that of JME, decrease inNOx emissions is expected. Similar reductions (4-5%) arealso witnessed by Knothe et al.33

Measured CO emissions are lowest withKME and highestfor JME (Figure 7). The CO emissions are higher for JMEby38.4% and lower for KME by 23% as compared to diesel.Peterson and Reece34 reported a reduction up to 50% withpure biodiesel, whereas Hamaski et al.35 reported noticeableincrease in CO emissions with biodiesel. During the combus-tion,HC is first converted intoCOand then into CO2, thus, atrade-off between UHC and CO is expected. With a largeramount ofUHCsent to exhaust, better availability of oxygenis ensured for remaining fuel leading to complete combus-tion. JME emits lesserUHCas compared toKMEand henceCO emissions for JME are higher than KME.

Similarly, emissions of CO2 are also highest with JME andlowest with KME (Figure 7). The CO emissions with diesel,JME, and KME at full load are 4.6, 4.7, and 4.4%, respec-tively. The reduced UHC emission with JME and higheremissions of CO and CO2 shows better conversion of hydro-carbons into oxides of carbon.

4. Conclusions

The raw oils of Jatropha and Karanj have higher relativedensity but lower calorific value than that of diesel. The

kinematic viscosity and flash point of these raw oils are muchhigher than that of diesel. The FFA contents of karanj areusually higher than 5%, whereas fresh jatropha oil containseven less than 2%. The iodine value of jatropha (∼100 g) ishigher than that of karanj (∼80 g), but both are withinpermissible limits (∼115 g).

Transesterification leads tomajor changes in the propertiesof both the oils. On transesterification, the density of jatrophaand karanj oils falls to 0.8838 kg/m3 and 0.8749 kg/m3, thecalorific value falls to 39.40 and 39.19MJ/kg, cloud point fallsto 0� and2 �C,andpour point falls to less than-3� and-2 �C,respectively. Significant changes are observed in kinematicviscosity, flash point, and FFA contents on transesterifica-tion, whereas no change in iodine value is found. The viscositydrops to 8.3 and 6.5 cSt at 32 �C, flash point drops to 118� and122 �C, and FFA drops to 0.3 and 0.5% for jatropha andkaranj oils respectively.

During engine trials, KME gave better thermal efficiencyand specific fuel consumption than JME, but both ester fuelsperformedpoorer thandiesel. TheBTHEfor diesel, JME, andKME at full load is found as 26.49, 22.69, and 24.03%; andBSFC as 0.29, 0.39, and 0.34 kg/kWh, respectively. Theexhaust temperature was 427, 383, and 393 �C and indicatedpower developed was 5.41, 5.09, and 5.19 kW, whereas brakepower was almost the same for all fuels indicating lower losseswith esters. The peak rate of pressure rise is highestwithdiesel,but the position of peak rate with esters advances with largeramount of heat release in mixing controlled combustionregime.KMEshiftsmore as compared to JME.The emissionsof UHC, NOx, and smoke opacity are found highest withdiesel. About 50% reduction inUHC, 25% reduction inNOx,and 20% reduction in smoke opacity is observed with esterfuels. COandCO2 emissions were higher with JMEand lowerwith KME when compared to diesel emission.

Acknowledgment. Theauthors acknowledge the financial sup-port provided by PetroleumConservationResearchAssociation,Ministry of Petroleum and Natural Gas, Government of India,for carrying out this research.

(32) Graboski, M. S.; McCormick, R. L.; Alleman, T. L.; Herring, A.M.The Effect of Biodiesel Composition on Engine Emissions from aDDCSeries 60 Diesel Engine; National Renewable Energy Laboratory: 2003;NREL/SR-510-31461(33) Knothe, G.; Sharp, C. A.; Ryan, T. W. Energy Fuels 2006, 20,

403–8.(34) Peterson, C. L.; Reece, D. Trans. ASAE 1996, 39 (3), 805.(35) Hamasaki, K.; Kinoshita, E.; Tajima, H.; Takasaki, K.; Morita,

D. Combustion characteristics of diesel engines with waste vegetable oilmethyl ester. In: The 5th international symposium on diagnostics andmodeling of combustion in internal combustion engines, (COMODIA2001).

comparative evaluation of combustion, performance, and emissions of jatropha

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