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EXTRACTION, CHARACTERIZATIONAND ENGINE PERFORMANCEOF JATROPHA CURCAS OIL

Mohd. Yunus Khan'

AbstractGlobal concern about escalating energy demand,depleting fossil fuel reserves and increasingenvironmental pollution has given an impetus to explorealternative fuels, preferably renewable. Plants oils are arenewable source of combustible material whose energycontent can be beneficially utilized for transportationpurposes. In this paper, the performance of a dieselengine running on pure Jatropha Curcas Oil (JCO) wasexperimentally investigated. JCO was supplied at twodifferent temperatures- 35°C and 65°C. The importantcharacteristic properties of JCO were found to becompatible with the requirement of diesel engine fuel.The comparison of fuels was made in terms of brakethermal efficiency, fuel consumption, pressure versuscrank angle diagram and exhaust gas temperature. Thetest results show decrease in thermal efficiency andincrease in fuel consumption and exhaust gastemperature for unheated JCO operation. Larger ignitiondelay and lower peak cylinder pressure was observedwith it. However, engine performance was found toimprove when JCO was preheated. This performancewas in between that obtained with diesel and unheatedJCo. On the whole, it can be concluded that for short-term usage, JCO (preheated to 65°C) can be directlyused instead of diesel, without any operational difficultyand modification in engine design.

'Mechanical Engineering Section,University Polytechnic,Aligarh Muslim University, Aligarh.

'Department of Chemical Engineering,National Institute of Technology, Rourkela.

Saroj Kumar Padhi' and R.K.Singh!

Introduction

The increasing industrialization andmotorization of the techno sawy world has led toa steep rise in the demand for petroleum-basedfuel. These fuels are obtained from natural fossiloil reserves, which are very limited. These finitereserves are highly concentrated in certainregions of the world, which increasesdependence on a few oil rich nations.Furthermore, these reserves are graduallydepleting and burning of these fuels has asevere destructive impact on the environment. Inthe context of the above problem. The search foralternative fuels has become extensive. Theenergy used in different power sectors is basedon diesel and it is, therefore essential thatalternatives to diesel be developed. The need ofthe hour is to utilize renewable energyresources. For this reason, biofuels are beingresearched worldwide as alternative fuels.Vegetable oils are bio-origin based fuels. Theyare non-toxic and eco-friendly. They have rapidbio-degradability, their sources are renewableand they can be obtained easily. They operate ina diesel engine just like petrol-diesel, therebythey require no major modification in enginedesign [1-5]. Thus, vegetable oils hold greatpotential as an alternative fuel for diesel engineswithout any major modification. The partial orfullreplacement of diesel with these oils will relievethe pressure on existing fuel reserves as well as

conserve a lot of diesel, thereby savingsubstantial money. As there is a tremendousdemand for edible oils as food and they are fartoo expensive to be used as fuel at present, sothe use of non-edible oils compared to edible oilsis very significant.

In the present investigation, non-edible jatrophacurcas oil (JCO) is used as an alternative fuel inunmodified diesel engines. Jatropha curcas is awidely occurring variety of tree born oil seeds. Itgrows practically all over India under a variety ofagro-climatic conditions. Thus, it ensures areasonable production of seeds with very littleinputs.ln this present study, it is observed thatthere are various problems associated withstraight vegetable oils being used as fuel indiesel engines, mainly caused by their highviscosity [2,6-8]. Although short-term tests usingneat vegetable oil showed promising results,longer tests showed various engine problemssuch as carbonization of injector, piston headand surfaces of cylinder, gum development,engine deposits, wear of vital parts, ring stickingand thickening of the lubricating oil etc [2,8-11].These experiences led to the use of modifiedvegetable oil as a fuel. In order to use vegetableoils in existing engine design, their viscosity hadto be reduced. Solution of the viscosity problemcan be approached through various techniquessuch as blending with lighter oils [1,4-6,9],preheating (i.e. increasing fuel inlet temperature)[1,8,10-11] and transesterification i.e.conversion to methyl/ethyl esters referred to asbiodiesel [2-5].

The objective of this experimental work is tostudy the effect of fuel preheating onperformance of the diesel engine running onJCO. During this investigation, the engine wasfuelled with JCO at two different fuel inlettemperatures- at 35°C (ambient temperature)and 65°C (elevated fuel inlet temperature). Dieselwas used as a baseline fuel. For comparisonpurposes, the short-term performance tests havebeen carried out using three fuels.

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2. Jatropha curcas oil

Jatropha curcas oil is non-edible oil, which isobtained from the dried ripe seeds of theJatropha curcas plant. Jatropha curcas is alarge shrub or tree native to the American tropicsbut commonly found and utilized throughoutmost of the tropical and subtropical regions ofthe world [9,12]. It is commonly known as Physicnut, Ratanjot, Jamalghota, Jangaliarandi orKala-aranda [13]. It is a drought-resistant,perennial plant, and has the capability to grow onmarginal/poor soils. It requires very littleirrigation and grows in all types of soils [1].

The Jatropha curcas plants start yielding fromthe second year of plantation but in limitedquantity. If managed properly, it starts giving 4-5kg per tree seed production from 5th yearonwards and seed yield can be obtained upto 50years from the day of plantation. The oil contentof Jatropha seed ranges from 30 to 50% byweight [13]. The oil can be combusted as fuelwithout being refined. It burns with a clearsmoke-free flame, tested successfully as fuel indiesel engines. Jatropha oil cake containsnitrogen, phosphorus and potassium, so it canbe used as organic manure. Jatropha seedpress cake and Jatropha oil have insecticidalproperties.

In spite of a number of advantages Jatropha alsosuffers from certain limiting factors, which needto be kept in mind while dealing with this species.Jatropha seeds are hard and possess toxicity.Thus the de-oiled cake cannot be used as,animal fodder . After extraction of oil from theseeds the detoxification of the seed cake isnecessary so that the seed cake can be used ascattle feed. From several investigations it isfound that de-acidification and bleaching couldreduce the content of toxic phorbol esters to 55%[14]. The fatty acid composition of JCO consistsof myristic, palmitic, stearic, arachidic, oleic andlinoleic acids [9,15]. Fatty acid composition ofJCO is shown in Table 1. The main benefits ofjatropha are renewable energy, erosion control

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and soil improvement, promotion ofemployment and poverty reduction.

Table 1:Fatty acid profile of JCO [12]

Fatty Acid Formula Structure Wt%

Myristic Acid C12H2802 14:0 0.5-1.4

Palmitic Acid C16H3202 16:0 12-7.0

Stearic Acid C18H3602 18:0 5.0-9.7

Oleic Acid C18H3402 18:1 37-63

Linoleic Acid C18H3202 18:2 19-41

3.Extraction of oil

Before oil extraction, the jatropha seeds shouldbe roasted for around 10 minutes or can be solarheated for several hours. The seeds should notbe overheated. The process breaks down thecells containing the oil and eases the oil flow.The heat also liquefies the oil, which improvesthe extraction process. Oil can be extracted fromthe seeds by heat, solvents or by pressure.Extraction by heat is not used commercially forvegetable oils. The oil from Jatropha seeds canbe extracted by three different methods. Theseare mechanical extraction using a screw press,solvent extraction and an intermittent extractiontechnique viz. soxhlet extraction. Although oilextraction can be done with or without seedcoat, for Jatropha, utilization of a mechanical dehulling system (to remove the seed coat) canincrease oil yield by 10%.Choosing efficientextraction methods can increase the yield bymore than 5%. While in cold pressing «60°C),around 86 - 88% efficiency is achieved, hotpressing (110 - 120°C) can increase it to around90%. On the other hand, the solvent extractionmethod enhances the efficiency up to 99%.

A disadvantage with solvent extraction is that thequantity of phospholipids in solvent extracted oilis twice as high as compared to pressed oil. Thisnecessitates a further step of oil de gummingbefore trans-esterification. Oil extractionmethods are also being developed based onfermentation hydrolysis. In this process, cellwalls of the oil plant seeds are destroyedfollowed by the release of the oil present within

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the cells [16]. This new method not onlyproduces higher quality of oil and cake but alsorequires much less energy and results in lowerlevels of environmental pollution. The efficiencyso far obtained is 86% and more research isneeded to develop an effective enzyme system.In order to purify the extracted oil, the oil mustundergo a series of steps. The first step issedimentation which is the easiest way to getclear oil, but it takes about a week until thesediment is reduced to 20-25 % of the raw oilvolume. In the second step the purificationprocess can be accelerated tremendously byboiling the oil with about 20 % water. The boilingshould continue for few hours until the water hascompletely evaporated and the oil thenbecomes clear. Then the raw oil is again filteredwhich is a very slow process.

rf--+' J<l.t:roph.Curc&JOllTw(P~ Hulme; DMse,1AnUlCtmlnt) Tw

C I EngineJ~ketW&terlnlel

Figure 1: Experimental Setup

4. Experimentations

4.1 Experimental Set-up

The DI diesel engine ( Kirloskar make) was usedfor conducting the experimentations. Fig.1shows the engine test rig mounted on a rigidbase frame. The specifications of theexperimental set-up are given in Table 2. Engineis coupled to an eddy current dynamometer bycardon shaft. Experimental setup is provided

with different equipments and instruments for themeasurement of air flow, fuel flow, cylinderpressure, crank angle, speed, varioustemperatures and load. A rotameter is providedfor engine cooling water flow measurement.Piezoelectric type pressure sensor is used forcylinder pressure measurement. The sensor ismounted in the cylinder head of the engine. Thesensor is provided with a water-cooled adapter.These signals are interfaced to a control panel,which is connected to a computer to monitor theengine performance at different runningconditions.

Table 2: Engine Specifications

Engine Kirloskar (Model TV1),

single cylinder, four

stroke, water cooled

diesel engine.

Bore x Stroke 0.0875 m x 0.110 m

Compression ratio 17.5: 1

Rated power 5.2 kW @ 1500 rpm

Stroke volume 661 cc

Fuel and air measurement Differential pressure unit

Speed measurement Rotary encoder

Dynamometer Eddy current

Load measurement Strain gauge load cell,

Range 0-50 kg

Water flow measurement Rotameter

Fuel and air measurement Differential pressure unit

Speed measurement Rotary encoder

In order to use plant oil as fuel, a minormodification in the existing set-up was made. Thefuel system was designed and held differenttanks: a conventional fuel tank for the test fueland a secondary fuel tank for diesel (used onlyfor starting and stopping the engine). A fuel filterwas provided at the outlet of the JCO tank. JCOwas heated in the fuel tank by means of athermostatically controlled immersion rod andwas allowed to flow to the fuel pump through a

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fuel measuring unit. In order to compensate fortemperature loss of vegetable oil, a heatexchanger was fitted between the fuelmeasuring unit and fuel pump. A tube-in-shelltype of heat exchanger was designed andfabricated, which was cylindrical in shape. Thefuel was passed through a copper tube, whichwas coiled within the heat exchanger shell. Theheat exchanger, vegetable oil tank and hot watertank were mounted on a suitable stand. The heatexchanger shell was completely insulated tominimize heat losses. Three calibrated Copper-Constant temperature probes (of range -1S0°C to390° C) were attached to a heating arrangementfor measurement of different temperatures.

4.2 Experimental Procedure

Experiments were initially carried out on theengine with diesel as the fuel to obtain baselinedata. The same test procedure was thenrepeated for JCO at different temperatures (35°Cand 65°C). Then, comparative assessment oftest fuels was made. Engine water flow rate andcalorimeter water flow rates were adjusted at 350LPH and SO LPH respectively. The injectiontiming was optimized and set at 2r bTDC.Injection timing and injection pressure were notchanged for all fuels. For carrying out tests withJCO, the engine was started with diesel andallowed to warm up and computer software wasallowed to get fully loaded. Then, the diesel fuelvalve was shut down and JCO valve was openedto run the engine. Instrument readings for aparticular test case were recorded after asufficiently long time that ensure steady stateengine operation. The engine was tested underdifferent load conditions for a constant speed of1500 rpm. The comparison of two fuels wasmade in terms of thermal efficiency, fuelconsumption, in-cylinder pressure and exhaustgas temperature. At the end of the experiment,the fuel was always switched back to diesel andthe engine was run until all alternative fuel hadbeen purged from the fuel lines, injection pumpand injector in order to prevent engine deposits.

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The same test procedure was repeated forpreheated JCO. The fuel temperature was theonly parameter that was changed and thechanges in the performance of the engine mustbe due to these temperature changes.

5. Results and Discussions

The engine tests were carried out using JCO attwo different temperatures (35°C and 65°C). Theperformance characteristics of JCO are thencompared with diesel and shown here withsuitable graphs. The results and relateddiscussions are given below.

5.1 Fuel characteristics

Before the engine test, the important chemicaland physical properties of JCO wereexperimentally determined as per standardsmethods. Table 3 shows the comparison ofproperties of JCO with diesel. Except cetanenumber determination of other properties wascarried out in the laboratory by standardmethods. Determination of flash point, calorificvalue, density, and kinematic viscosity werecarried out using Pensky's Martin apparatus,Bomb calorimeter, Hydrometer and Sayboltviscometer respectively.

The flash point of JCO was observed to be muchhigher than that of diesel. Hence, it is safer inhandling, transportation and storage. However,high flash point attributes to its lower volatilitycharacteristics [5]. The calorific value of JCO isobserved to be lower than that of diesel. Thepresence of chemically bound oxygen invegetable oils improves combustion propertiesand emissions but lowers their calorific value [1-5]. The density of JCO is slightly higher than thatof diesel. The cetane number of JCO is 38 ascompared 50 for diesel. Thus, the propensity ishigherfor diesel knock in case of JCO operation.At 38°C, kinematic viscosity of JCO is very highin comparison to diesel. This is due to the largemolecular mass and chemical structure of

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Table 3: Fuel Characterization [9]IPropertylFuel lCO Diesel ASTM Apparatus

Method

/Flash Point (C) 219 76 D93 Pensky'sMartinApparatus

Calorific Value 39.7342.01 D240 BombMl/kg) Calorimeter

Density 0.9150.858 D 1298 Hydrometer(glcm3, at 30°C)

Cetane Number* 38 50 - -Kinematic 40.972.96 D445 SayboltViscosity Viscometer(cSt, at 38°C)

vegetable oil [1,9,11].

5.2 Kinematic Viscosity vs Temperature

From the properties listed in Table 3, it has beenobserved that JCO has a higher kinematicviscosity compared to baseline fuel. Theviscosity of JCO needed to be reduced more inorder to make it suitable as fuel to be used indiesel engines. From the literature [9-11], it hasbeen found that on heating, the viscosity ofvegetable oils reduces. Therefore, efforts hadbeen made to decrease the viscosity by heatingJCO. For this, the kinematic viscosities weremeasured at varying temperatures in the rangeof 20-80°C.

.Q50~~ 40v

~ 30

~:;: 20

10O~~~~~~========~~~o 10 20 30 40 50 60 -0 80 90

Fuel Temperature rC)

Fig. 2: Kinematic Viscosity Vs Temperature

Fig.2 shows that the kinematic viscosity of JCOis higher than that of diesel at all fueltemperatures. However, the viscosity of JCOreduced considerably with the increase intemperature, which is a result of decrease in

35 .---~----~----~--~-----,----,

~ 30 1- , , : :.:;;A~ .oR~~25 1- , , ~~~ ; ; 1="·0E 20 I- ~ ~; ;~~ ,·········1f:l

"E 15 l- -':/..."-=•.• 10"""ee~

--Diesel// ;....... ,···············;············1__ Jeo (Unheated)

_ Jeo (Preheated)O~~~~~~~~~==~==~o 234

Brake Power (k"V)6

Fig. 3: Brake Thermal Efficiencyvs Brake Power

2.2 r------,------,-----,--------,-----' •..-x--:::---'2E-········,···········.··········.········· ; ../"": /c I

1.8 »r:~ 1.6 ~ .............•.. ··········.············/····.v···/:::·····;·······./ / ..~ .

i:~1:-....... ,····x···. y/....··v···;;.;:::.;-.-if·····~ .~ I ~ , _/ ...•........~~~~ ; ! .

~0.8-7>~~~0.6 ~.;: 0.4 ~~. .l 7 - ~--;:[}Di;es;clel----I,i.I ~ reo (Unheated)0.2 1:-......... , ..............•.................. ,..... II-cr- Jeo (Preheated) ..

OL~l.......~~~~~.1::::i:=:::i:::::=:;:::::;:Jo 2 3 4 6

Brake Power (kW)

Fig. 4: Fuel Consumption vs Brake Power

intermolecular attraction due to expansion. Fordiesel, viscosity change with temperature wasnot so significant.

5.3 Performance characteristics

The results for the variation in the brake thermalefficiency with brake power for test fuels arepresented in Fig.3. It can be seen that brakethermal efficiency with unheated JCO operationis quite low as compared to that of dieseloperation. The maximum brake thermalefficiency with unheated JCO is 22.5% whereas itis 31.6% with diesel at maximum output power.Fig.4 shows the variation of engine fuelconsumption with respect to brake power for testfuels. The fuel consumption in the case ofunheated JCO is significantly higher ascompared to diesel operation for the entireoutput power range.

The poor engine performance is a reflection of

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the high viscosity, low volatility, low cetanenumber and high density of JCO as compared todiesel. Kinematic viscosity of JCO is nearly 14times higher than that of diesel. High viscosityand low volatility of vegetable oil based fuelgreatly effects the fuel injection process andresults in poor atomization of the fuel [1,17].Also, cetane number of JCO is lower than dieselby approximately 12 units. These factorscombine to increase delay period. Delay periodis the time period between the start of fuelinjection and onset of combustion. On the otherhand, the high density of JCO leads to a largermass injection of fuel particles for the samedisplacement of the plunger in the fuel injectionpump [9]. On the other hand, when preheatedJCO is used, increased brake thermal efficiencyand reduced fuel consumption rate is obtained.This is due to reduction in viscosity and densityand improved volatility. Further, brake thermalefficiency and fuel consumption values obtainedwith preheated JCO are still inferior to thoseobtained with baseline fuel operation.

80r---------------?=~7===~70

'i:' 60

e 50t~ 40e~ 30 t·········,·······:.§ 20(;

10

°F-===~-10L--~.i..-_-,--~~~--'-_~ __ ~

270 300 330 360 390 420 450Crank Angle (deg.)

Fig. 5: Cylinder Pressure vs Crank Angle(Power 5.25 kWat 1500 rpm InjectionPressure 250 bar Injection Timing 270 bTDC)

In-cylinder pressure data was analyzed forchange in pressure with respect to crank anglefor test fuels. Fig.5 shows the pressure versuscrank angle diagram for three fuels at an engineof 1500 rpm and maximum power output. Fromthis diagram, it can be clearly seen that delayperiod of unheated JCO operation is largest. Thestart offuel injection was the same for all fuels butthe injection duration for unheated JCO isobserved to be the largest. It is measured by the

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sudden change in the slope of pressure crankangle diagram. The possible reason for this ishigher viscosity, lower volatility and lowercetane number of JCO and perhaps tocompensate for the lower calorific value of fuel.Also, the maximum cylinder pressure withunheated JCO is the lowest. When preheatedJCO is used, injection duration reduces whilepeak cylinder pressure increases. Thepreheated JCO showed reduction in delayperiod compared to unheated JCO. Thisimprovement has resulted from decrease in oilviscosity and improved volatility. Further, we seethat peak cylinder pressure value withpreheated JCO lies in between those obtainedwith diesel and unheated JCO.

400

~ ....---..~ : : ........ ~ ...

~~'?Y

~

I -.- Diesel I.-- JCO (Unheated) ..I ~ JCO (Preheated)

350G~ 300~=1i! 250i;~ 200

f-<

~ 150

-; 100

~r.l 50

oo 4

Brake Powe r (kW)

Fig. 6: Exhaust Gas Temperaturevs Brake Power

The variation of exhaust gas temperature usingdiesel, unheated JCO and preheated JCO ispresented in Fig. 6. The exhaust gastemperature obtained with unheated JCO isquite higher than that with diesel. The maximumtemperature of exhaust gas at maximum outputpower is 304°C with unheated JCO and 285°Cwith diesel. In case of JCO operation, higherdelay period results in slow combustion.Because of this, injected vegetable oil particlesmay not get enough time to burn completelybefore TDC, hence some fuel mixtures tend toburn during early part of expansion stroke (after-burning occurs). It can be further seen that withthe increase in fuel inlet temperature(preheating), the exhaust gas temperature

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tends to increase. This is due to increase incombustion gas temperature [11].

6. Conclusions and Recommendations

In this investigation, JCO was tested as analternative diesel engine fuel. The short-termperformance test was carried out on a dieselengine separately with diesel and JCO(unheated and preheated). In order to evaluateengine performance no modification in theexisting engine design was made. It was foundthat JCO had a good potential as an alternate fordiesel. The most important advantage of thisnon-edible oil is that it is a renewable source ofenergy compared to petroleum fuel.

The engine performance with unheated JCOwas found to be poorer in comparison withbaseline fuel. Unheated oil exhibits a largerdelay period and longer combustion durationwith moderate rate of pressure rise and lowerpeak cylinder pressure. Higher exhaust gastemperature was also observed with it. Thereason for this difference may be attributed tohigh viscosity, high density, low cetane number,low calorific value and poor volatility of JCO. Dueto these inferior properties, JCO produces poorengine performance. The properties can beimproved through various methods liketransesterification, blending (with lighter oils)and preheating.In the present study, improvement in propertieswas achieved by preheating the oil. Whenpreheated JCO was used, engine performancewas found to improve. Acceptable values ofbrake thermal efficiency and fuel consumptionrate were observed with oil preheated to 65°C.The heated JCO showed a comparativereduction in a delay period over the unheatedJCO. Also, higher peak cylinder pressure wasobserved with it. This performance was stillslightly inferior as compared with baseline fueloperation. A series of experimentations must becarried out using preheated JCO. Continuedengine performance, emission, combustion anddurability of engine will increase consumer andmanufacturer confidence. Studies are alsoneeded on economic feasibility of this energysources.A thorough investigation is required in order toestablish long-term durability of diesel enginerunning of pure JCO. A comprehensive work is

needed to conclude that vegetable oil basedfuels can be completely substituted for diesel inexisting diesel engine designs.AcknowledgementsThe authors of this paper are grateful to theDepartment of Mechanical Engineering, Z. H.College of Engineering and Technology, AligarhMuslim University, Aligarh for kindly providing thefacilities to conduct the engine test. Further, theauthors would like to thank Mis. Mohd. Ali andRahis Beg for their technical help in conductingexperiments.NomenclatureJCODILPHTDC

bTDCrpmcStkW

References

Jatropha Curcas OilDirect InjectionLitre Per HourTop Dead CenterBefore Top Dead CenterRevolutions per minuteCenti StrokesKiloWatt

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