an experimental comparison of methods to use methanol and jatropha oil in a compression ignition...

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Biomass and Bioenergy 25 (2003) 309–318

An experimental comparison of methods to use methanol andJatropha oil in a compression ignition engine

M. Senthil Kumar∗, A. Ramesh, B. NagalingamDepartment of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036, India

Received 28 October 2002; received in revised form 30 December 2002; accepted 7 January 2003

Abstract

In this work various methods of using vegetable oil (Jatropha oil) and methanol such as blending, transesteri1cation anddual fuel operation were studied experimentally. A single cylinder direct injection diesel engine was used for this work. Testswere done at constant speed of 1500 rev min−1 at varying power outputs. In dual fuel operation the methanol to Jatrophaoil ratio was maintained at 3:7 on the volume basis. This is close to the fraction of methanol used to prepare the ester withJatropha oil.

Brake thermal e5ciency was better in the dual fuel operation and with the methyl ester of Jatropha oil as compared tothe blend. It increased form 27.4% with neat Jatropha oil to a maximum of 29% with the methyl ester and 28.7% in thedual fuel operation. Smoke was reduced with all methods compared to neat vegetable oil operation. The values of smokeemission are 4.4 Bosch Smoke Units (BSU) with neat Jatropha oil, 4:1 BSU with the blend, 4 BSU with methyl ester ofJatropha oil and 3:5 BSU in the dual fuel operation.

The Nitric Oxide (NO) level was lower with Jatropha oil compared to diesel. It was further reduced in dual fuel operationand the blend with methanol. Dual fuel operation showed higher hydrocarbon (HC) and carbon monoxide (CO) emissionsthan the ester and the blend.

Ignition delay was higher with neat Jatropha oil. It increased further with the blend and in dual fuel operation. It wasreduced with the ester. Peak pressure and rate of pressure rise were higher with all the methods compared to neat Jatropha oiloperation. Jatropha oil and methyl ester showed higher di<usion combustion compared to standard diesel operation. However,dual fuel operation resulted in higher premixed combustion. On the whole it is concluded that transesteri1cation of vegetableoils and methanol induction can signi1cantly enhance the performance of a vegetable oil fuelled diesel engine.? 2003 Elsevier Ltd. All rights reserved.

Keywords: Diesel engine; Jatropha curcas L.; Transesteri1cation; Methyl ester of Jatropha oil; Methanol; Dual fuel operation;Performance and emissions

1. Introduction

Vegetable oils can be directly used in diesel en-gines as they have a high cetane number and calori1c

∗ Corresponding author.E-mail address: [email protected] (M. Senthil Kumar).

value very close to diesel. However, the brake thermale5ciency is inferior to diesel. They also lead to prob-lems of high smoke, HC and CO emissions. This isbecause the high viscosity and low volatility of veg-etable oils lead to di5culty in atomizing the fuel andin mixing it with air. Further, gum formation and pis-ton sticking under long-term use due to the presence

0961-9534/03/$ - see front matter ? 2003 Elsevier Ltd. All rights reserved.doi:10.1016/S0961-9534(03)00018-7

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310 M. Senthil Kumar et al. / Biomass and Bioenergy 25 (2003) 309–318

Nomenclature

ppm Parts per millionBTDC Before top dead centerBSU Bosch Smoke UnitsHC HydrocarbonCO Carbon monoxideNO Nitric oxideCA Crank angleDDA system Digital data acquisition system

of oxygen in their molecules and the reactivity of theunsaturated HC chains are problems with vegetableoils [1,2].

Several approaches have been tried by researchersto use vegetable oils e5ciently in diesel engines.Some of them like preheating the oil, blending it withdiesel/alcohol, use of semi-adiabatic engine compo-nents, dual fuelling with gaseous and liquid fuels, etc.have been found to be e<ective [3–5]. Transesteri1ca-tion of vegetable oils showed improved performanceand reduced emissions. This process needs eitherethanol or methanol. A speci1ed amount of methanolis mixed and allowed to react with the vegetable oilin the presence of a catalyst like NaOH or KOH ata temperature of 70◦C. Transesteri1cation of veg-etable oil provides a signi1cant reduction in viscosity,thereby enhancing the physical properties. The cetanenumber is also improved. It has been reported that themethyl ester of vegetable oils o<ers low smoke levelsand high thermal e5ciencies than neat vegetable oils[6]. The methyl ester of vegetable oils also lead toimproved heat release rates [7]. The power output wasfound to be superior to pure vegetable oils. However,the transesteri1cation process requires approximately3 h for making the ester and a further 12 h for sep-aration. It also results in by products such as fattyacids and glycerol. These by products cannot be usedas fuels in engines though they have other uses.

Vegetable oils o<er the advantage of freely mix-ing with alcohols and these blends can be used inthe existing diesel engines without modi1cations. Itis also a simple process. Blending of vegetable oilswith methanol results in signi1cant improvement intheir physical properties. The viscosity and density areconsiderably reduced. The volatility is also improved.

Vegetable oils in varying proportions in the fuel blendwere tried by a number of investigators. Results ob-tained form the experiments on a diesel engine usinga blend of vegetable oil and alcohol showed improvedbrake thermal e5ciency and reduced exhaust smokeemissions than neat vegetable oils [8,9]. However, themaximum quantity of alcohol that can be blended islimited by the presence of water in alcohol. High quan-tities lead to separation.

Dual fuel approach is a well-established techniqueto use di<erent types of fuels in diesel engines. Aconventional diesel engine can be easily modi1ed tooperate in this mode. This engine can accept a widerange of liquid and gaseous fuels as the primary en-ergy source [10,11]. In a dual fuel engine, a volatilefuel with a high octane number is inducted along withair through the intake manifold and is ignited by in-jecting a small quantity of diesel called the pilot fuel.Alcohols can be used as inducted fuels in dual fueloperation. Since vegetable oils produce high smokeemissions, dual fuel approach can be a viable optionfor improving their performance. Vegetable oils canbe used as the pilot fuel and alcohol can be the in-ducted fuel. The high Jame velocity of alcohols willalso improve the overall combustion process.

In this work, di<erent methods of using methanol toimprove the performance of vegetable oil in a dieselengine like blending, transesteri1cation and dual fu-eling were compared while using Jatropha oil as theprimary fuel. Jatropha oil is non-edible oil obtainedfrom the Jatropha curcas plant. Important propertiesof Jatropha oil like calori1c value and cetane num-ber are very close to diesel and hence it was selectedfor this work. Transesteri1cation requires methanol(about 30% by volume of the vegetable oil methanolmixture) for making the methyl ester of vegetable oil.It was also found that the quantity of alcohol that canbe blended with vegetable oil is limited to 30% (byvolume of the mixture) and hence the same amountof methanol was used for preparing the blend also.In dual fuel operation the inducted methanol quantitywas varied from 0% to about 80% of the total volumeof methanol and Jatropha oil used. However, compar-ison was made at the condition when methanol con-tributed 30% by the total volume of the fuel. Jatrophaoil was injected in a conventional way.

A single cylinder water-cooled direct injectiondiesel engine developing a power output of 3:7 kW

M. Senthil Kumar et al. / Biomass and Bioenergy 25 (2003) 309–318 311

Table 1Properties of diesel, methanol, Jatropha oil and methyl ester of Jatropha oil (Refs. [8,12])

Properties Diesel Jatropha oil Methyl ester of MethanolJatropha oil

1. Density (kg m−3) 840 918.6 880 7902. Calori1c value (kJ kg−1) 42 490 39 774 38 450 19 6743. Viscosity (cst) 4.59 49.93 5.65 —4. Cetane number 45–55 40–45 50 3–55. Flash point (◦C) 50 240 170 —6. Carbon residue (% ) 0.1 0.64 0.5 0.0

was run at the rated speed of 1500 rev min−1 atvarious power outputs. Performance, emission andcombustion parameters were obtained and analyzed.The performance with neat diesel and neat Jatrophaoil have been used as the basis for comparison.

2. Transester�cation process

Jatropha oil was converted into its methyl ester bythe transesteri1cation process. This involves makingthe triglycerides of Jatropha oil to react with methylalcohol in the presence of a catalyst (NaOH/KOH)to produce glycerol and fatty acid ester. Speci1edamount (1000 ml) of Jatropha oil (450 ml) methanoland (10 g) sodium hydroxide were taken in a roundbottom Jask. The contents were stirred till ester for-mation began. The mixture was heated to 70◦C andheld at that temperature without stirring for 1 h, thenit was allowed to cool overnight without stirring. Twolayers were formed. The bottom layer consisted ofglycerol and top layer was the ester. The propertiesof diesel, Jatropha oil and methyl ester of Jatrophaoil are given in Table 1. The fatty acid distribution ofJatropha oil has been compared with those of rapeseedoil and Soyabean oil in Table 2.

3. Experimental setup and experiments

A Single cylinder 4-Stroke water-cooled diesel en-gine developing 3:7 kW at 1500 rev min−1 was usedfor the research work. Engine details are given inTable 3. The Schematic of the experimental setupis shown in Fig. 1. A high speed digital dataacquisition system in conjunction with a piezo-electric transducer was used for the measure-

Table 2Engine details

1. General details Four stroke, compression ignition, water-cooled, single cylinder engine

2. Bore & stroke 80 mm × 120 mm3. Compression ratio 15:14. Rated output 3:7 kW at 1500 rev min−1

5. Injector openingpressure

170 bar

6. Fuel injection timing 27◦ BTDC static (for diesel)29◦ BTDC static (for Jatropha oil andthe ester)

ment of cylinder pressure history. An infrared ex-haust analyzer was used for the measurement ofHC/CO in the exhaust. For measuring NOx a Rose-mount Analytical, Model 951A Chemilumines-cent NO=NOx Analyzer was also utilized. Smokelevels were obtained using a Bosch system.

Experiments were initially carried out on theengine-using diesel as the fuel to provide base linedata. The injection timing was optimized and set at27◦ before TDC (static) with diesel and 29◦ BTDCwith Jatropha oil. The same timing was used for allother modes also. The cooling water temperature atthe outlet was maintained at 70◦C. The engine speedwas held at 1500 rev min−1 and the power outputwas varied.

4. Results and discussion

4.1. Performance

The variation of brake thermal e5ciency with brakepower output is shown in Fig. 2. Owing to poor mix-ture formation, as a result of the low volatility and


Table 3Fatty acid distribution of Jatropha oil, Rapeseed oil and soyabean oil (% by wt) (Refs. [13–16])

S.No. Fatty acid Jatropha oil Rapeseed oil Soya bean oil

1 Myristic acid 0.1 1 0.12 Palmitic acid 14.1–15.3 3.5 11.43 Stearic acid 3.7–9.8 0.9 3.24 Arachidic acid 0.3 0.4–2.4 0.25 Behenic acid 0.2 0.6–2.5 0.3–2.46 Palmitoleic acid 1.3 0–0.1 0.1–17 Oleic acid 34.3–45.8 64.1 21.88 Linoleic acid 29–44.2 12–22 54.99 Linolenic acid 0.3 7–9 8.3

1 2

9

65

78

12

11

13 1514

16 1817

10

20

21

3 4

LEGEND

1.Engine 9.Carburetor 17.Lub oil Temp. Indictr2.Dynamometer 10. Silencer 18. Rotameter3.Alcohol Tank 11. Smoke Pump 19.Pressure Sensor4.Diesel Tank 12. HC/CO Analyzer 20. Charge Amplifier5.Burette ( Alcohol ) 13. Stop Watch 21.DDA.System6.Burette ( Diesel ) 14.RPM Indicator7. Air Tank 15. Ext Temp Indicator8. Air Flow meter 16. Coolant Temp. Indr

1 2

9

65

78

12

11

13 1514

16 1817

10

20

21

19

3 4

LEGEND

1.Engine 9.Carburetor 17.Lub oil Temp. Indictr2.Dynamometer 10. Silencer 18. Rotameter3.Alcohol Tank 11. Smoke Pump 19.Pressure Sensor4.Diesel Tank 12. HC/CO Analyzer 20. Charge Amplifier5.Burette ( Alcohol ) 13. Stop Watch 21.DDA.System6.Burette ( Diesel ) 14.RPM Indicator7. Air Tank 15. Ext Temp Indicator8. Air Flow meter 16. Coolant Temp. Indr

Fig. 1. Experimental setup.

higher viscosity the thermal e5ciency is lower withJatropha oil as compared to diesel. The maximumbrake thermal e5ciency with Jatropha oil is about27.4% where as it is 30.3% with diesel at maximumpower output. The brake thermal e5ciency is higherwith methyl ester of Jatropha oil, 30% methanol blendand in dual fuel operation with 30% methanol induc-tion by volume compared to pure Jatropha oil. The

maximum values are 29%, 28.1 % and 28.7%, respec-tively. The methyl ester of Jatropha oil and the blendhave lower viscosity and density than the pure oil.The reduction in viscosity leads to improved atomiza-tion, fuel vaporization and combustion. In addition theignition delay time is closer to diesel with the esteras the cetane rating is higher. Due to faster burningof methanol in the blend the thermal e5ciency was


0 1 2 3 4

Brake Power (kW)

8

10

12

14

16

18

20

22

24

26

28

30

32

Bra

ke T

her

mal

Eff

icie

ncy

(%

)

Speed 1500 rpmInj.Timing

Diesel : 27 BTDCJatropha oil : 29 BTDC

ME of Jatropha oil : 29BTDC

Std diesel

Pure Jatropha oil

30 % Methanol

ME of Jatropha oil

Dual fuel

Fig. 2. Variation of brake thermal e5ciency with brake power.

improved. This will be shown later in the heat releasecurves. In dual fuel operation there is a rise in theheat release rate due to rapid combustion of methanolby Jame propagation and the thermal e5ciency is in-creased as compared to neat Jatropha oil operation. Inthe dual fuel mode when the amount of methanol wasincreased beyond 30% (by volume) the brake thermale5ciency improved further. It reached a maximum of30.7% at 67% by volume of methanol admission. Itis noted that the brake thermal e5ciency at this pointis higher than neat diesel mode. However, at lowerpower outputs dual fuel option showed inferior per-formance. At light loads a signi1cant proportion ofthe fuel inducted through the intake does not burncompletely due to low quantity of the pilot fuel, lowcylinder gas temperature and lean methanol air mix-ture which is inducted [10]. The comparison of thee5ciency at part loads indicates that the performancewith methyl ester of Jatropha oil is better comparedto all other methods.

The variation of volumetric e5ciency with poweroutput is shown in Fig. 3. The volumetric e5ciencieswith Jatropha oil and its ester are lower than diesel.This is due to the higher temperature of the retainedexhaust, which will preheat the incoming fresh air andlower the volumetric e5ciency. However, there wasa slight improvement in volumetric e5ciency with

0 1 2 3 4

Brake Power ( kW )

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

97

98

Vo

lum

etri

c E

ffic

ien

cy (

%)


Std diesel : 27 BTDCJatropha oil : 29 BTDC

ME of Jatropha oil : 29 BTDC

Std diesel

Jatropha oil

30 % Methanol

ME of Jatropha oil

Dual fuel

Fig. 3. Variation of volumetric e5ciency with brake power.

0 1 2 3 4

Brake Power (kW)

100

150

200

250

300

350

400

450

Exh

aust

Gas

Tem

p (D

eg C

)



ME of Jatropha oil : 29BTDC

Std diesel

Jatropha oil

30 % Methanol

ME of Jatropha oil

Dual fuel

Fig. 4. Variation of exhaust gas temp with brake power.

methanol induction in dual fuel operation due to thevaporization of methanol, which results in increasedair density and volumetric e5ciency.

Exhaust gas temperature plotted in Fig. 4 is higherwith Jatropha oil than diesel. This is due to slow com-bustion of Jatropha oil. The maximum temperature of


0 1 2 3 4Brake Power ( kW )

0

1

2

3

4

5

Sm

oke

No

(B

osc

h S

mo

ke U

nit

s)

Std diesel

Jatropha oil

30 % Methanol

ME of Jatropha oil

Dual fuel




Fig. 5. Variation of smoke NO with brake power.

exhaust gas at peak load is 428◦C with the Jatropha oiland 415◦C with the methyl ester of Jatropha oil. Themaximum exhaust temperature is 402◦C with diesel.There is a reduction of exhaust gas temperature withthe blend of methanol and in the dual fuel operation. Itwas about 410◦C with the blend and 412◦C with dualfuel operation at maximum power output. The reduc-tion in exhaust gas temperature is due to the higherlatent heat of vaporization of methanol.

4.2. Exhaust emissions

The variation of smoke emission with power outputis shown in Fig. 5. With Jatropha oil smoke emissionis increased particularly at higher loads due to pooratomization of the fuel. Smoke level at the maximumpower output of 3:7 kW is 4:4 BSU with the pureJatropha oil. The smoke level with diesel is 3:8 BSUat maximum power. However, there is a drastic re-duction of smoke emission in dual fuel operation withmethanol induction. The smoke emission was 3:4 BSUat peak power output in the dual fuel operation with30% methanol. This is due to combustion of carbu-reted methanol, which is substituted for Jatropha oil.The induction of methanol also reduces the quantityof injected fuel and lowers the smoke emission. In-creasing the methanol admission beyond 30% leads

0 1 2 3 4Brake Power (kW)

0

20

40

60

80

100

120

140

160

180

200

220

240

260

HC

(p

pm

)

Std diesel

Jatropha oil

30 % Methanol

ME of Jatropha oil

Dual fuel

Fig. 6. Variation of HC with brake power.

to a further more reduction in smoke emission uptothe value of 2:6 BSU at 67% of methanol substitution(at best e5ciency point). Thus, dual fuel operationcan be used to control the smoke level and increasethe brake thermal e5ciency with vegetable oils. Withmethyl ester of Jatropha oil and the blend also therewas a reduction of smoke emission. The values are4 and 4:1 BSU with methyl ester and the blend.

The HC concentration found in the exhaust is shownin the Fig. 6. Jatropha oil exhibits higher HC emis-sions compared to standard diesel operation. The HCemission is 100 ppm with diesel and 130 ppm withneat Jatropha oil. Poor mixing with air is the main rea-son for this. However, HC emission is lower with themethyl ester of Jatropha oil and the blend as comparedto pure Jatropha oil. The value is 110 ppm with bothmethyl ester of Jatropha oil and the methanol blend.The HC emission was 150 ppm in the dual fuel oper-ation at maximum power output. CO emission levelsare also higher with both Jatropha oil and methyl esterof Jatropha oil as compared to diesel at all loads as in-dicated in Fig. 7. The lower brake thermal e5ciencyand calori1c value with Jatropha oil and its methylester lead to injection of higher quantities of the fuelfor the same power output as compared to diesel. Indual fuel operation the HC and CO emissions areconsiderably higher. This is due to quenching of the



0.00

0.04

0.08

0.12

0.16

0.20

0.24

0.28

0.32

0.36

CO

(%)

Speed 1500 r pmInj.Timing

Std diesel : 27 BTDCJatropha oi l : 29 BTDC


Std diesel

Jatropha oil

30 % Methanol

ME of Jatropha oil

Dual fuel

Fig. 7. Variation of CO with brake power.

0 1 2 3 4

Brake Power (kW)

0

100

200

300

400

500

600

700

800

900

NO

(pp

m)


Std diesel : 27BTDCJatropha oil : 29 BTDC


Std diesel

Jatropha oil

30 % Methanol

Jatropha Ester

Dual fuel

Fig. 8. Variation of NO with brake power.

methanol air Jame on the walls and also due to lowtemperature. This is a typical feature in all dual fuelengines [11]. The induction of methanol reduces themass of air inducted and leads to higher CO emissions.

Fig. 8 indicates that Jatropha oil shows lower nitricoxide (NO) emission as compared to standard dieseloperation due to the lowered premixed burning rate

0 1 2 3 4Brake Power ( kW)

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

Igni

tion

Del

ay (d

egC

A)




Std diesel

Jatropha oil

30 % Methanol

ME of Jatropha oil

Dual fuel

Fig. 9. Variation of ignition delay with brake power.

following the delay period. This is due to lower airentrainment and fuel air mixing rates. However, indual fuel operation and in the blend, NO was furtherreduced to 713 and 723 ppm, respectively. This is dueto the reduction in the charge temperature due to va-porization of methanol. The NO level with methylester is higher as compared to the normal mode andis lower than diesel values.

4.3. Combustion parameters

The variation of ignition delay is shown in Fig. 9.Jatropha oil and its methyl ester showed longer igni-tion delays as compared to diesel due to lower cetanenumbers. The ignition delay is 11◦ CA with Jatrophaoil and 10◦ CA with the methyl ester. With the blendand in dual fuel operation also there was an increaseof ignition delay. They are 12◦ CA and 13◦ CA withthe blend and in dual fuel operation. Due to the cool-ing e<ect produced by the methanol as it vaporizes,the ignition delay is increased.

Peak pressure mainly depends on the combustionrate in the initial stages, which is inJuenced by thefuel taking part in uncontrolled heat release phase. Thehigh viscosity and low volatility of the Jatropha oillead to poor atomization and mixture preparation withair during the ignition delay period. The peak pressure



50

52

54

56

58

60

62

64

66

Cyl

ind

er P

eak

Pre

ssu

re (b

ar)

Std diesel

Jatropha oil

30 % Methanol

ME of Jatropha oil

Dual fuel

Speed 1500 rpmInj. Timing

Std diesel : 27 B TDCJatopha oil : 29 B TDC


Fig. 10. Variation of peak pressure with brake power.

0 1 2 3 4

Brake Power (kW)

0

1

2

3

4

5

6

Ma

x.R

ate

of

Pr.

Ris

e (

ba

r/d

eg

CA

)

Std diesel

Jatropha oil

30 % Methanol

ME of Jatropha oil

Dual fuel




Fig. 11. Variation of MRPR with brake power.

and the maximum rate of pressure rise are as a resultlowest with neat vegetable oil operation (Figs. 10 and11). The peak pressure with the ester and the blendare higher due to the improvement in preparation ofair fuel mixture as a result of low fuel viscosity. Indual fuel operation, the vegetable oil accumulated dur-ing the ignition delay period burns with the methanol

0 1 2 3 4Brake P ower (kW )

5

10

15

20

25

30

35

40

45

50

55

60

Co

mb

ust

ion

Du

rati

on

(deg

CA

)




Std diesel

Jatropha oil

30 % Methanol

ME of Jatropha oil

Dual Fuel

Fig. 12. Variation of combustion duration with brake power.

entrained along with it and leads to high heat releaserates as compared to neat Jatropha oil operation. Theheat release rate in the dual fuel mode becomes veryhigh, as the amount of methanol is increased. Normaldiesel operation showed the highest peak pressure andmaximum rate of pressure rise.

Combustion duration (Fig. 12) increases with risein power output with all the fuels due to increase inthe quantity of fuel injected. Higher combustion du-ration was observed with Jatropha oil than diesel. Theincrease in combustion duration is mainly due to theslow combustion of the injected fuel. However, it isreduced with the methyl ester of Jatropha oil and theblend as compared to the pure Jatropha oil. In the dualfuel operation due to burning of the inducted methanolby Jame propagation the combustion duration isincreased.

The premixed burning is more with diesel (Fig. 13).Once the autoignition of the fuel commences, the pres-sure rises, entering into the rapid or premixed com-bustion phase. It is clear that the premixed heat re-lease of Jatropha oil was lower than the methyl ester ofJatropha oil and the blend and hence the thermal e5-ciency was reduced. The di<usion-burning phase in-dicated under the second stage is greater for Jatrophaoil. At the time of ignition, less fuel air mixture isprepared for combustion with the vegetable oil; there-fore, more burning occurs in the di<usion phase rather


340 360 380 400 420

Crank Angle (deg)

-10

0

10

20

30

40

50

60

70

80

Hea

t Rel

ease

Rat

e (J

/deg

CA

)

Speed 1500rpmInj.Timing


Load 100%

Std diesel

Neat Jatropha oil

ME of Jatropha oil

30% Blend

Fig. 13. Variation of heat release rate at peak power output.

340 360 380 400 420Crank Angle (deg)

-10

0

10

20

30

40

50

60

70

80

Hea

t Rel

ease

Rat

e (J

/deg

CA

)

Speed 1500 rpmInj.Timing : 29 BTDC

Fule: Jatropha oilLoad 100%

Dual fuel

Jatropha oil

Fig. 14. Variation of heat release rate in dual fuel operation.

than in the premixed phase. A comparison of heatrelease between the neat Jatropha oil and dual fuelmodes is made at 100% load in Fig. 14. In the dualfuel operation there is a rise in premixed phase of theheat release rate. This is due to the rapid combustionof the inducted fuel. At part loads dual fuel operationshowed poor heat release rates (Fig. 15). Methyl esterof Jatropha oil shows higher heat release rates always

340 350 360 370 380 390 400 410 420

Crank Angle (deg)

-10

0

10

20

30

40

50

60

70

Hea

t Rel

ease

rat

e (J

/ deg

CA

)

Speed 1500 rpmInl.Timing

Std diesel : 27 BTDCJatopha oil : 29 BTDC

ME of Jatropha oil : 29 BTDCLoad : 40%

Jatropha oil

ME of Jatropha oil

Std diesel

Dual Fuel

Fig. 15. Variation of heat release rate at part load condition.

as compared to neat Jatropha oil. It is also seen thatJatropha oil shows high heat release rates late in theexpansion stroke, which is the reason for high exhausttemperatures.

5. Conclusion

From the experimental results the followingconclusions were made:

1. Single fuel operation with neat Jatropha oil and itsesters:1.1. Jatropha oil resulted in a slightly reduced ther-

mal e5ciency as compared to diesel. With themethyl ester of Jatropha oil the brake thermale5ciency is comparable to diesel values. Max-imum brake thermal e5ciencies are 27.4%,29% and 30.2% with Jatropha oil, its methylester and diesel.

1.2. HC emission is higher with Jatropha oil ascompared to diesel. It is 130 ppm for Jatrophaoil and 100 ppm for diesel at maximum output.However, it is 110 ppm only with the methylester of Jatropha oil. Similar trends are seen inthe case of CO emission also.

1.3. The maximum smoke level with Jatropha oilis 4:4 BSU and it is 4 BSU with its ester. Inthe case of diesel it is 3:8 BSU.


1.4. Ignition delay and combustion duration are in-creased with both Jatropha oil and methyl es-ter of Jatropha oil as compared to diesel.

1.5. Lower heat release rates are found with Jat-ropha oil and methyl ester of Jatropha oil ascompared to diesel during the premixed com-bustion phase.

2. Using Jatropha oil methanol blend as compared toneat Jatropha oil resulted in:2.1. An increase in brake thermal e5ciency from

27.4% to 28.1%.2.2. A good reduction of exhaust gas temperature

from 428◦C to 410◦C.2.3. Lowering of HC and CO emissions.2.4. Reduced smoke levels from 4.4 to 4:1 BSU.2.5. Increase in ignition delay.

3. Dual fuel operation with methanol induction andJatropha oil as the pilot fuel resulted in:3.1. A signi1cant increase in the brake thermal ef-

1ciency. with vegetable oil. The peak brakethermal e5ciency rose from 27.4% to 28.7%.

3.2. A good reduction in smoke level from 4.4 to3:4 BSU at the maximum power output.

3.3. Increased HC and the CO emissions.3.4. A reduction in NO level of from 736 to

713 ppm.3.5. Higher ignition delay, peak pressure, maxi-

mum rate of pressure rise and premixed com-bustion rate.

On the whole it is concluded that Jatropha oil can beused as fuel in diesel engines directly and by blendingit with methanol. Use of methyl ester of Jatropha oiland dual fuel operation with methanol induction cangive better performance and reduced smoke emissionsthan the blend. Dual fuel operation showed the lowestsmoke and NO levels. The penalty is an increase inHC and CO emissions.

Acknowledgements

The authors thank Mr. K. Chandrasekhar consul-tant, Jatropha plantations & oil extractions, JAT-ROPHA OIL Seed Development & Research, Hyder-abad, for supplying the oil and providing informationon the preparation of the methyl ester.

References

[1] Barsic NJ, Hunke AL. Performance and emissioncharacteristics of a naturally aspirated diesel engine withvegetable oils. SAE Paper No. 810262, 1981.

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an experimental comparison of methods to use methanol and jatropha oil in a compression ignition...

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