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Renewable Energy 33 (2008) 1147–1156

www.elsevier.com/locate/renene

Performance evaluation of a vegetable oil fuelledcompression ignition engine

Deepak Agarwala, Lokesh Kumarb, Avinash Kumar Agarwalb,�

aEnvironmental Engineering and Management Program, Indian Institute of Technology Kanpur, Kanpur 208 016, IndiabDepartment of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur 208 016, India

Received 28 June 2007; accepted 29 June 2007

Available online 6 August 2007

Abstract

Fuel crisis because of dramatic increase in vehicular population and environmental concerns have renewed interest of scientific

community to look for alternative fuels of bio-origin such as vegetable oils. Vegetable oils can be produced from forests, vegetable oil

crops, and oil bearing biomass materials. Non-edible vegetable oils such as linseed oil, mahua oil, rice bran oil, etc. are potentially

effective diesel substitute. Vegetable oils have high-energy content. This study was carried out to investigate the performance and

emission characteristics of linseed oil, mahua oil, rice bran oil and linseed oil methyl ester (LOME), in a stationary single cylinder, four-

stroke diesel engine and compare it with mineral diesel. The linseed oil, mahua oil, rice bran oil and LOME were blended with diesel in

different proportions. Baseline data for diesel fuel was collected. Engine tests were performed using all these blends of linseed, mahua,

rice bran, and LOME. Straight vegetable oils posed operational and durability problems when subjected to long-term usage in CI engine.

These problems are attributed to high viscosity, low volatility and polyunsaturated character of vegetable oils. However, these problems

were not observed for LOME blends. Hence, process of transesterification is found to be an effective method of reducing vegetable oil

viscosity and eliminating operational and durability problems. Economic analysis was also done in this study and it is found that use of

vegetable oil and its derivative as diesel fuel substitutes has almost similar cost as that of mineral diesel.

r 2007 Elsevier Ltd. All rights reserved.

Keywords: Vegetable oil; Blending; Biodiesel; Transesterification; Particulate matter

1. Introduction

Energy demand is increasing due to ever increasingnumber of vehicles employing internal combustion engines.Also, world is presently confronted with the twin crisis offossil fuel depletion and environmental degradation. Fossilfuels are limited resources; hence, search for renewablefuels is becoming more and more prominent for ensuringenergy security and environmental protection. For thedeveloping countries of the world, fuels of bio-origin canprovide a feasible solution to the crisis. When RudolfDiesel invented the diesel engine more than a century ago,he demonstrated the principle of compression ignitionengine by employing peanut oil as fuel and suggested thatvegetable oils would be the future fuel for diesel engines.

e front matter r 2007 Elsevier Ltd. All rights reserved.

nene.2007.06.017

ing author. Tel.: +91 512 259 7982; fax: +91 512 259 7408.

ess: akag@iitk.ac.in (A.K. Agarwal).

However, petroleum was discovered later, which replacedvegetable oils as engine fuel due to its abundant supply.Thus, it is highly desired in present context to direct theresearch towards renewable fuels of bio-origin, which areenvironment friendly, provide improved performance,while being used as diesel substitute and must not beharmful to human health.India is producing a host of non-edible oils such as

linseed, castor, mahua, rice bran, karanji (Pongamia

glabra), neem (Azadirachta indica), palash (Butea mono-

sperma), kusum (Schlelchera trijuga), etc. Some of these oilsproduced even now are not being properly utilized, and ithas been estimated that some other plant-based and forestderived oils have a much higher production potential [1].Vegetable oils have comparable heat content, cetanenumber, heat of vaporization, and stoichiometric air/fuelratio with mineral diesel. Heat values decrease withincreasing un-saturation as a result of fewer hydrogen

ARTICLE IN PRESSD. Agarwal et al. / Renewable Energy 33 (2008) 1147–11561148

atoms in their molecular structure. The structure of typicalvegetable oil molecule is given below:

O CH2 –O--C—R1

O

CH—O—C—R2

O

CH2—O—C—R3

Here R1, R2 and R3 represent straight chain alkylgroups. Free fatty acids are also found in vegetable oils.The large molecular sizes of the triglycerides results in theoils having higher viscosity and low volatility compared tomineral diesel. Proportion and location of double bondsaffects cetane number of vegetable oils [1].

Problems associated with vegetable oils during enginetests can be classified into two broad groups, namely,operational and durability problems. Operational pro-blems are related to starting ability, ignition, combustionand performance. Durability problems are related todeposit formation, carbonization of injector tip, ringsticking and lubricating oil dilution. It has been observedthat the straight vegetable oils when used for long hourstend to choke the fuel filter because of high viscosity andinsoluble present in the straight vegetable oils. The highviscosity, polyunsaturated character, and extremely lowvolatility of vegetable oils are responsible for the opera-tional and durability problems associated with its utiliza-tion as fuels in diesel engines. High viscosity of vegetableoils causes poor fuel atomization, large droplet size andthus high spray jet penetration. The jet tends to be a solidstream instead of a spray of small droplets. As a result, thefuel is not distributed or mixed with the air required forburning in the combustion chamber. This result in poorcombustion accompanied by loss of power and economy.

Blending, cracking/pyrolysis, emulsification or transes-terification of vegetable oils may overcome these problems.Heating and blending of vegetable oils reduce the viscosityand improve volatility of vegetable oils but its molecularstructure remains unchanged hence polyunsaturated char-acter remains. Blending of vegetable oils with diesel,however, reduces the viscosity drastically (depending onlevel of blending) and the fuel handling system of enginecan handle the vegetable oil-diesel blends without anyproblems. On the basis of experimental investigations, it isfound that converting vegetable oils into simple esters is aneffective way to overcome all the problems associated withthe vegetable oils. Most of the conventional productionmethods for biodiesel use basic or acidic catalyst. Areaction time of 45min to 1 h and reaction temperature of55–65 1C are required for completion of reaction andformation of respective esters [1–10].

Biodiesel consists of alkyl ester of fatty acids pro-duced by the transesterification of vegetable oils. The useof biodiesel in diesel engines require no hardware

modifications. In addition, biodiesel is a superior fuel thandiesel because of lower sulfur content, higher flash pointand lower aromatic content. Biodiesel fuelled engine emitsfewer pollutants. Biodiesel can be used in its pure form oras a blend with diesel. It can also be used as a diesel fueladditive to improve its properties. Even a low percentblend, such as 2% biodiesel will provide sufficient lubricityfor low sulfur diesel [11].Saka and Kusdiana [2] prepared biodiesel using rapeseed

oil and supercritical methanol to investigate the possibilityof converting the triglycerides of the rapeseed oil torapeseed oil methyl esters (ROME). Murayama et al. [3]evaluated waste vegetable oils as a feedstock for biodieselproduction. This research was focused on the engineperformance and emission characteristics of esterifiedvegetable oil, when used in a diesel engine. When blendsof biodiesel and diesel are used in diesel engines, asignificant reduction in hydrocarbons (HC) and particulatematter (PM) are observed but NOx emissions are found tohave increased. In general, engine performance and powerremains unchanged [1,4–7,12]. Akasaka et al. [4] found thatunder partial load conditions, soybean methyl ester (SME)addition increases PM emissions.Agarwal [1,6,7] observed significant improvement in

engine performance and emission characteristics for thebiodiesel-fuelled engine compared to diesel-fuelled engine.Thermal efficiency of the engine improved, brake specificenergy consumption reduced and a considerable reductionin the exhaust smoke opacity was observed. Prasad et al.[13] used non-edible oils such as Pongamia and Jatrophaoils in low heat rejection (LHR) diesel engine. Esterifica-tion, preheating and increase in injection pressure havebeen tried for utilization of vegetable oils in diesel engines.The emission of smoke and NOx has been found toincrease.

2. Blending

Undoubtedly, transesterification is well-accepted andbest method of utilizing vegetable oils in CI engine with-out any long-term operational and durability problems.However, this adds to the cost of production becauseof the chemical process involved. In rural and remoteareas of developing countries, where grid power is notavailable, vegetable oils can play a vital role in decen-tralized power generation for irrigation and electrificationpurposes. In these remote areas, different types ofvegetable oils are available locally but it may not bepossible to chemically process them due to logisticsproblems. Hence, using blended vegetable oils is anattractive alternative. Keeping these facts in mind, a setof engine experiments were conducted using differenttypical oils available in rural areas on a type of engine,which is very frequently used for agricultural, irriga-tion and electricity generation purposes. The engineperformance is also compared with the transesterifiedfuel.

ARTICLE IN PRESSD. Agarwal et al. / Renewable Energy 33 (2008) 1147–1156 1149

3. Transesterification

The formation of methyl esters by transesterification ofvegetable oils requires 3moles of alcohol stoichiometri-cally. However, transesterification is an equilibrium reac-tion in which excess alcohol is required to drive thereaction close to completion. The vegetable oil waschemically reacted with an alcohol in presence of a catalystto produce vegetable oil esters. Glycerol was producedas a by-product of transesterification reaction. Thechemical reaction of the transesterification process isshown below:

O O

CH2 —O—C—R1 CH2 — OH R4–O—C—R1

O Catalyst O

CH—O—C—R2 + 3 R4OH CH — OH + R4 –O—C—R2

O O

CH2—O—C—R3 CH2—OH R4–O—C—R3

Triglyceride EstersGlycerolAlcohol

The mixture was stirred continuously and then allowedto settle under gravity in a separating funnel. Two distinctlayers form after gravity settling for 24 h. The upper layerwas of ester and lower layer was of glycerol. The lowerlayer was separated out. The separated ester was mixedwith some warm water (around 10% volume of ester) toremove the catalyst present in ester and allowed to settleunder gravity for another 24 h. The catalyst gets dissolved

Table 1

Cost of biodiesel produced from linseed oil

Biodiesel from linseed oil

Linseed oil (98% yield of ester)

Methanol

Reagents

Electricity

Purification

Labor

Sub total

Revenue from by-product (glycerol) sales

Total (cost less revenue)

Cost in USD/l

Table 2

Cost of different CI engine fuels

Diesel Linseed oil

Cost (USD/l) 0.787 0.866

Cost after subsidy (USD/l) 0.787 (already included) 0.735

Density (kg/l) 0.842 0.8945

Cost (USD/kg) 0.935 0.822

Calorific value (MJ/kg) 45.343 39.75

Cost (USD/MJ) 0.0206 0.0207

in water, which was separated. Moisture was removed fromthis purified ester using silica gel crystals. The ester wasthen blended with mineral diesel in various concentrationsfor preparing biodiesel blends to be used in CI engine forconducting various engine tests. The process of transester-ification brings about a drastic change in the density oflinseed oil and the linseed oil methyl ester (LOME) hasalmost similar density as that of mineral diesel.

4. Economic analysis

The cost of making biodiesel from linseed oil is shown inTable 1. However cost of different vegetable oils keepsfluctuating since the markets are small. The costs ofdifferent fuels assumed in this study are given in Table 2.For diesel, cost was taken as the 2007 fuel price inIndia.The cost of vegetable oils is slightly higher than diesel

because of the fragmented nature of vegetable oil market.There are several middle-men involved which increase thecost of vegetable oils. The cost of diesel is relatively lowerbecause of the cross-subsidy offered by administered pricemechanism of the government. If same subsidy is given tovegetable oils to be used as substitute fuel then it can beseen from Table 2 that its cost comes near to that ofmineral diesel. Table 2 also shows that cost of vegetableoils per kilogram is lower than diesel but calorific value ofvegetable oil is also lower than diesel hence cost per unit ofenergy produced is almost same for the vegetable oils anddiesel. Therefore, use of vegetable oil or biodiesel in diesel

Cost (Rs/l)

38.75

4.05

0.85

0.20

0.35

1.20

45.4

4.35

41.05

0.933

Mahua oil Rice bran oil Linseed oil methyl ester (LOME)

0.844 0.977 0.933

0.713 0.846 0.802

0.9040 0.9163 0.874

0.789 0.923 0.918

38.863 39.5 40.37

0.0203 0.0234 0.0227

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Table 3

Fuel properties

Fuel Properties

Specific

gravity

Calorific value

(MJ/kg)

Carbon residue

(%)

Ash content

(%)

Pour point

(1C)

Flash point

(1C)

Water content

(%)

Kinematic viscosity (cSt at

40 1C)

Mahua oil 0.9040 38.863 0.4215 0.021 15 238 Trace 37.18

Linseed oil 0.8645 39.75 0.4222 0.034 �5 108 Trace 16.23

Rice bran

oil

0.9163 39.5 – – – – Trace 44.52

Diesel 0.842 45.343 0.0337 0.006 o�5 47 Trace 2.44

Table 4

Specifications of the compression ignition engine

Manufacture Kirloskar, India

Engine type Single cylinder, four stroke, water cooled, diesel engine

Bore/stroke (mm) 87.5/110

Displacement volume (l) 0.662

Rated speed (rpm) 1500

Rated power (kW) 4

Nozzle pressure (bar) 200

Inlet valve opens/inlet valve closes 4.51 BTDC/35.51 ABDC

Exhaust valve opens/exhaust valve closes 35.51 BBDC/4.51 ATDC

D. Agarwal et al. / Renewable Energy 33 (2008) 1147–11561150

engine costs almost same as mineral diesel. If the vegetableoil crop cultivation program is implemented under acooperative structure, the use of vegetable oils to partiallysubstitute mineral diesel will also make economic sense.Various researchers have also shown that use of vegetableoils and their derivatives is economical and comparable tomineral diesel [14–17].

5. Experimental setup

The present study was carried out to investigate theperformance and emission characteristics of linseed oil,mahua oil, rice bran oil and LOME in a stationary singlecylinder four-stroke diesel engine and compare it withbaseline data of diesel fuel. Specific gravity of differentfuels was measured using a precision hydrometer. Kine-matic viscosity was measured using kinematic viscometer(Setavis, UK). Calorific value and flash point weremeasured using bomb calorimeter and pensky marten’sclosed cup flash point apparatus respectively. Karlfischer titrator was used to measure water content. Carbonresidue was measured using Conradson carbon residuetester. To measure ash content, 10 g sample of fuel wastaken in a crucible and heated at 600 1C for 2 h. Ashformed after heating and combustion was weighed todetermine ash content of the fuel. Cloud and pour pointapparatus was used to measure pour point of dif-ferent fuels. Fuel properties of these oils and diesel arecompared in Table 3. The linseed oil, mahua oil, rice bran

oil and LOME were blended with diesel in differentproportions.Considering the specific features of diesel engine, a

typical engine that is widely used in agricultural sector,was selected for present investigation. Technical specifi-cations of the engine are given in Table 4. The engine wascoupled to an electrical generator (Fig. 1). The majorpollutants in the exhaust of a diesel engine are smoke andoxides of nitrogen. AVL 437 smoke meter was used tomeasure the smoke density of the exhaust from dieselengine. It works on the light extinction principle. Lightfrom a source is passed through a standard tube contain-ing the exhaust gas sample from the engine. A photovol-taic device measures intensity of transmitted light at itsother end.The engine was operated on diesel first and then on

vegetable oils and LOME blends. The different fuel blendsand mineral diesel were subjected to performance andemission tests on the engine. The performance data werethen analyzed from the graphs recording thermal efficiency,brake-specific energy consumption, and smoke density forall fuels. The optimum condition was found out from thegraphs based on maximum thermal efficiency and smokedensity considerations.The brake-specific fuel consumption is not a very reliable

parameter to compare different fuels, as the calorific valuesand the densities are different. Hence, brake-specific energyconsumption (BSEC) is a more reliable parameter forcomparison. Based on thermal efficiency, BSEC, and

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To Smoke Opacity Meter

Exhaust Gas

AC

GeneratorLoad

Bank

V

I

Exhaust

Temperature

Air Box

U-Tube Water

Manometer

Orifice Meter

Fuel

Tank

Fuel Burette

Fuel Valve

Fig. 1. Schematic diagram of experimental setup.

D. Agarwal et al. / Renewable Energy 33 (2008) 1147–1156 1151

smoke density, all the curves were compared to base-linediesel curve in order to optimize blend concentration.

6. Results and discussion

Different blends of linseed oil (10, 20, 30, and 50%, v/v),mahua oil (10, 20, and 30%, v/v), rice bran oil (10, 20, and30%, v/v) and LOME (10, 20, 30, 50, and 100%, v/v) withmineral diesel were prepared. Engine experiments wereconducted at a constant speed of 1500 rpm at differentloads.

6.1. Performance and emission characteristics for linseed oil

blends

All linseed oil blends showed almost similar thermalefficiency at lower loads (as shown in Fig. 2). Fifty percentlinseed oil blend is found more efficient than other blendswith maximum thermal efficiency. BSEC is also almostsimilar for all blends (as shown in Fig. 3). BSEC is alsofound lowest for 50% linseed oil blend. However, in Fig. 4,smoke density is higher for 50% blend compared to allother linseed oil blends.

6.2. Performance and emission characteristics for mahua oil

blends

It can be observed in Fig. 5 that all mahua oil blendshave almost similar thermal efficiency. Compared to allblends, 30% mahua oil blend is found to be most thermally

efficient. Fig. 6 shows that 30% mahua oil blend showsmarginally better BSEC than other blends. However, it canbe observed that BSEC is better at lower loads and it isnear to BSEC for diesel at higher loads. Fig. 7 shows thatsmoke density is higher for mahua blends compared todiesel at lower loads. Smoke density increased withproportion of mahua oil in diesel.

6.3. Performance and emission characteristics for rice bran

oil blends

The characteristics curves for rice bran oil blends areshown in Figs. 8–10. Fig. 8 shows almost similar thermalefficiency for all rice bran oil blends. Similarly, in Fig. 9,20% rice bran oil blend showed minimum BSEC thanother blends. In Fig. 10, 20% rice bran oil showed animproved performance as far as smoke density is con-cerned. Smoke density first decreases with addition of ricebran oil in diesel and then increases with further additionof rice bran oil in diesel.

6.4. Performance and emission characteristics for LOME

blends

The trend of the thermal efficiency curve (Fig. 11)generally improved by mixing biodiesel in mineral diesel.The thermal efficiency of the engine is found to improve byincreasing concentration of biodiesel in the blend. Twentypercent biodiesel blend showed maximum thermal effi-ciency. However, thermal efficiency decreased with further

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0

15

30

45

60

75

90

0 5 10 15 20 25 30 35 40 45 50

B.M.E.P. (N/m2x104)

Sm

oke D

en

sit

y (

%)

Diesel

10% Linseed

20% Linseed

30% Linseed

50% Linssed

Fig. 4. Smoke density for diesel and different blends of linseed oil.

0

5

10

15

20

25

30

35

0 5 10 15 20 25 30 35 40 45 50

B.M.E.P. (N/m2x104)

Th

erm

al E

ffic

ien

cy (

%)

Diesel

10% Linseed

20% Linseed

30% Linseed

50% Linseed

Fig. 2. Thermal efficiency for diesel and different blends of linseed oil.

10

15

20

25

30

35

40

0 5 10 15 20 25 30 35 40 45 50

B.M.E.P. (N/m2x104)

BS

EC

(kJ/h

r/kW

x10

3) Diesel

10% Linseed

20% Linseed

30% Linseed

50% Linseed

Fig. 3. BSEC for diesel and different blends of linseed oil.

D. Agarwal et al. / Renewable Energy 33 (2008) 1147–11561152

addition of biodiesel to mineral diesel. An importantobservation is that all biodiesel blends have thermalefficiency higher than mineral diesel. The possible reasonfor improved thermal efficiency may be more completecombustion, and additional lubricity of biodiesel [18]. Themolecule of biodiesel has some oxygen that takes part in

combustion and results in complete combustion. In Fig. 12,BSEC also shows similar trends. It decreased withincreasing concentration of biodiesel in mineral diesel.BSEC is found minimum for 20% biodiesel blend.However, BSFC is slightly higher for biodiesel blends thanmineral diesel. The reason for higher BSFC is lower

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0

15

30

45

60

75

0 5 10 15 20 25 30 35 40 45 50

B.M.E.P. (N/m2x104)

Sm

oke D

en

sit

y (

%)

Diesel

10% Mahua

20% Mahua

30% Mahua

Fig. 7. Smoke density for diesel and different blends of mahua oil.

0

5

10

15

20

25

30

35

0 5 10 15 20 25 30 35 40 45 50

B.M.E.P. (N/m2x104)

Th

erm

al E

ffic

ien

cy (

%)

Diesel

10% Mahua

20% Mahua

30% Mahua

Fig. 5. Thermal efficiency for diesel and different blends of mahua oil.

10

15

20

25

30

35

40

0 5 10 15 20 25 30 35 40 45 50

B.M.E.P. (N/m2x104)

BS

EC

(kJ/h

r/kW

x10

3) Diesel

10% Mahua

20% Mahua

30% Mahua

Fig. 6. BSEC for diesel and different blends of mahua oil.

D. Agarwal et al. / Renewable Energy 33 (2008) 1147–1156 1153

calorific value of biodiesel compared to mineral diesel. Itcan be observed in Fig. 13 that smoke density for biodieselblends is generally lower than that of diesel. Twentypercent LOME showed improved smoke emission perfor-mance than other blends. However, at lower loads, 100%LOME showed slightly higher smoke density than otherblends. At higher loads, all blends of LOME showed betteremission performance than that of diesel. The reason for

lower smoke density for biodiesel blend may be better andcomplete combustion of fuel due to oxygen atom present inthe molecule of biodiesel itself.

7. Conclusions

The prospects for large-scale vegetable oil-based fuelproduction are very attractive for developing countries like

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10

15

20

25

30

35

40

0 5 10 15 20 25 30 35 40 45 50

B.M.E.P. (N/m2x104)

BS

EC

(kJ/h

r/kW

x10

3) Diesel

10% Rice bran

20% Rice bran

30% Rice bran

Fig. 9. BSEC for diesel and different blends of rice bran oil.

0

15

30

45

60

75

0 5 10 15 20 25 30 35 40 45 50

B.M.E.P. (N/m2x104)

Sm

oke D

en

sit

y (

%)

Diesel

10% Rice bran

20% Rice bran

30% Rice bran

Fig. 10. Smoke density for diesel and different blends of rice bran oil.

0

5

10

15

20

25

30

35

0 5 10 15 20 25 30 35 40 45 50

B.M.E.P. (N/m2x104)

Th

erm

al E

ffic

ien

cy (

%)

Diesel

10% Rice bran

20% Rice bran

30% Rice bran

Fig. 8. Thermal efficiency for diesel and different blends of rice bran oil.

D. Agarwal et al. / Renewable Energy 33 (2008) 1147–11561154

India. In the present investigation, a host of blends ofdifferent vegetable oils, ester with mineral diesel oil wereprepared and tested on a single-cylinder constant speeddiesel engine for its performance and emission. Theperformance and emission parameter for different fuelblends were found to be very close to diesel. Smoke densityand BSFC were slightly higher for vegetable oil blendscompared to diesel. However, BSEC for all oil blends was

found to be lower than diesel. Vegetable oil blends showedperformance characteristics close to diesel. Therefore,vegetable oil blends can be used in compression ignitionengines in rural areas for agriculture, irrigation andelectricity generation. Economic analysis was also con-ducted to find out cost of biodiesel after transesterification.Comparative study of cost for different vegetable oils,biodiesel and mineral diesel shows that cost per unit energy

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10

15

20

25

30

35

40

0 5 10 15 20 25 30 35 40 45 50

B.M.E.P. (N/m2x104)

BS

EC

(kJ/h

r/kW

x10

3) Diesel

10% LOME

20% LOME

30% LOME

50% LOME

100% LOME

Fig. 12. BSEC for diesel and different blends of LOME.

0

5

10

15

20

25

30

35

0 5 10 15 20 25 30 35 40 45 50

B.M.E.P. (N/m2x104)

Th

erm

al E

ffic

ien

cy (

%)

Diesel

10% LOME

20% LOME

30% LOME

50% LOME

100% LOME

Fig. 11. Thermal efficiency for diesel and different blends of LOME.

0

15

30

45

60

75

0 5 10 15 20 25 30 35 40 45 50

B.M.E.P. (N/m2x104)

Sm

oke D

en

sit

y (

%)

Diesel

10% LOME

20% LOME

30% LOME

50% LOME

100% LOME

Fig. 13. Smoke density for diesel and different blends of LOME.

D. Agarwal et al. / Renewable Energy 33 (2008) 1147–1156 1155

produced is almost similar for all fuels. Modified main-tenance schedule may be adopted to control carbondeposits formed during long-term usage of vegetable oilblends. Esterification is a process, which changes molecularstructure of the vegetable oil molecules thus reducesviscosity and unsaturation. A diesel engine can performsatisfactorily on biodiesel blends without any engine

hardware modifications. Twenty percent LOME blendwas found to be the optimum concentration, whichimproved the thermal efficiency of the engine, reducedthe smoke density and BSEC. Using primary ester ofvegetable oil also eliminates the durability problemsassociated with the vegetable oil thus making it a safeand suitable fuel for long-term usage in CI engine.

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Acknowledgments

The authors acknowledge help, assistance, and sugges-tions of Mritunjay Shukla of Engine Research Laboratory,IIT Kanpur. Grant from Department of Science andTechnology, Government of India, for conducting theseexperiments is highly acknowledged.

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