effect of idling on fuel consumption and emissions of a diesel engine fueled by jatropha biodiesel...

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Journal of Cleaner Production xxx (2014) 1e8

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Journal of Cleaner Production

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Effect of idling on fuel consumption and emissions of a diesel enginefueled by Jatropha biodiesel blends

S.M. Ashrafur Rahman*, H.H. Masjuki, M.A. Kalam, M.J. Abedin, A. Sanjid, S. ImtenanCentre for Energy Sciences, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia

a r t i c l e i n f o

Article history:Received 28 October 2013Received in revised form2 January 2014Accepted 12 January 2014Available online xxx

Keywords:BiodieselJatropha curcasIdlingEmissionsFuel consumption

* Corresponding author. Department of MechanicMalaya, 50603 Kuala Lumpur, Malaysia. Tel.: þ603 79

E-mail addresses: [email protected] (S.M.A. Rahman).

0959-6526/$ e see front matter � 2014 Elsevier Ltd.http://dx.doi.org/10.1016/j.jclepro.2014.01.048

Please cite this article in press as: Rahman, Sbiodiesel blends, Journal of Cleaner Product

a b s t r a c t

An engine running at low load and low rated speed is said to be subject to high idling conditions, a modewhich represents one of the major problems currently the transport industry is facing. During this time,the engine can not work at peak operating temperature. This leads to incomplete combustion andemissions level increase due to having fuel residues in the exhaust. Also, idling results in increase in fuelconsumption. The purpose of this study is to evaluate fuel consumption and emissions parameters underhigh idling conditions when diesel blended with Jatropha curcas biodiesel is used to operate a dieselengine. Although biodieselediesel blends decrease carbon monoxide and hydrocarbon emissions, theyincrease nitrogen oxides emissions in high idling modes. Compared to pure diesel fuel, fuel consumptionalso increases under all high idling conditions for biodieselediesel blends, with a further increaseoccurring as blend percentage rises.

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1. Introduction

Adaptability, reliability, higher combustion efficiency andhandling facilities are the reasons behind wide acceptance of dieselfuel around the world (Ribeiro et al., 2007). In present, transportindustry largely depends upon diesel fuel. But, currently this sectoris facing some problems while using diesel fuel. It has been re-ported that, the major source of environmental pollution is theemissions from fossil fuel (Mofijur et al., 2013). These emissionsmay rise up to 39% by the end of 2030 if no stringent legislation isintroduced to limit the emissions from diesel fuel (Mofijur et al.,2012). Many countries have imposed environmental taxes to con-trol the emissions. Fig. 1 depicts environmental taxes as % of GDPfor different countries of European Union whereas Fig. 2 showsenvironmental taxes by categories: Energy taxes, Transport taxes,Pollution and Resource taxes (Environmental tax statistics, 2011).

Diesel fuel is non-renewable, it is depleting rapidly, and hencethe above situations accentuate research in a large scale to find outalternative renewable fuels which must be technically feasible,environmentally acceptable and domestically available. Also, theymust be able to fulfill the large energy demand. Nowadays the

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tendency to use renewable fuels has been proliferated due to lessproduction cost, rising fossil-fuel prices and carbon pricing.

Amongst many renewable fuels, biodiesel is rapidly becomingthe best option to substitute diesel fuel. This is due to its potentialto satiate the energy demand, abate global warming and green-house gasses (Shahabuddin et al., 2013). Throughout the world, theproduction of biodiesel has proliferated in the recent decade whenthe production was 19 thousand barrels per day in 2001, itincreased up to 403 thousand barrels per day in 2011 to 403thousand barrels per day, on the other hand, consumption raised to414 thousand barrels per day from 17.5 thousand barrels per day inthis same period of time (EIA). Biodiesel, also known as fatty acidmethyl ester, can be produced from vegetable oils or animal fats byemploying dilution, pyrolysis, trans-esterification and micro treat-ment (Singh and Singh, 2010). Biodiesel is non-flammable, biode-gradable, non-toxic, renewable, and environmentally friendly(Basha and Raja Gopal, 2012; Jayed et al., 2011). Biodiesel hassimilar properties like diesel fuel properties (Jayed et al., 2009; Linet al., 2011). The chief benefits of using biodiesel is that, it can beapplied with diesel as biodiesel-diesel blend at any proportion (Jainand Sharma, 2011). Moreover, absence of deleterious substance andlessened amount of harmful emissions to the environment arereason behind biodiesels continuous growth in popularity.

The use of biodiesel in diesel engine as blend has great impacton engine performance and emissions. Many researches have beencarried out to appraise the engine performance and emissions us-ing biodiesel and their blends (Atabani et al., 2013; Hussan et al.,

fuel consumption and emissions of a diesel engine fueled by Jatropha10.1016/j.jclepro.2014.01.048

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List of acronyms

APU Auxiliary power unitCO Carbon MonoxideDC Direct CurrentDFH Diesel fire heaterg/h Grams per hourHC HydrocarbonICE Internal Combustion EngineJB10 10% jatropha biodieselþ 90% DieselJB20 20% jatropha biodieselþ 80% Diesellt/h liters per hourMJ/kg Mega joules per kilo-gramNOx Nitrogen oxidesO2 OxygenPEMFC Proton exchange membrane fuel cellsRPM Revolutions per minuteSOFC Solid oxide fuel cellsTSE Truck stop electrificationTSS Thermal storage system

S.M.A. Rahman et al. / Journal of Cleaner Production xxx (2014) 1e82

2013). Researchers’ results showed that, diesel engine operatedwith biodieselediesel blends emit lesser amount of CO and HCemissions, whereas it increases NOx emissions (Alam et al., 2006;Ozsezen et al., 2009; Wu et al., 2009). Engine performance ishighly affected by the quality of biodiesel. Poor quality of biodieselwill result in deposits, corrosion, and excessive engine wear whichultimately accumulates to engine break-down (Bhale et al., 2009).Deposits and clogging due to use of biodiesel are major problemsfor diesel engine (Knothe, 2006; Lapuerta et al., 2008a,b). Depositson injectors due to the use of biodiesel will affect the fuel spraypattern, deposits in injector pump will affect the engine perfor-mance (Çetinkaya et al., 2005). Biodiesel may dilute lubrication on,which may lead to rising oil levels, loss of oil pressure and wornbearings. As biodiesel is a very effective solvent for some materialsused in engine, fuel leakage can become a vital problem. To avoidthese problems, it is important to make sure that the quality of thebiodiesel is excellent and the engine is “rated for biodiesel use”(Agarwal et al., 2003; Bhale et al., 2009).

Roy et al. (2013) investigated engine performance and emissionsduring high idling conditions. High idling is a critical problem forthe transport industry. The high idling operational condition isdefined as a condition in which the engine runs at low load and at

Fig. 1. Environmental taxes as % of GDP and a

Please cite this article in press as: Rahman, S.M.A., et al., Effect of idling onbiodiesel blends, Journal of Cleaner Production (2014), http://dx.doi.org/

low rated speed. After driving for a certain period, as it is imperativefor drivers to take a repose they keep the engine running idle tomaintain amenities, such as refrigerators, heating, microwave andair conditioning, and to provide power to the cab. Several studiesreported an average 6e16 h idling per day for long-haul trucks.Engine idling results in high fuel consumption. During this time, theengine can not work at peak operating temperature. This leads toincomplete combustion and emissions level increase due to havingfuel residues in the exhaust. Heretofore, many researches haveconducted to evaluate the engine performance and emissions usingonly diesel fuel at idling condition. Researchers found that, duringengine idling NOx emissions was 1.5 times higher than vehiclerunning on road (Lambert et al., 2002). Also, NOx increase withincreasing load during idling (Khan et al., 2006; Zietsman et al.,2005). During idling fuel consumption can be as high as 1.65 gal/h (Lim, 2002), CO emissions can be as high as 295 g/h (Storey et al.,2003), and HC emissions can be as high as 86.4 g/h (Brodrick et al.,2002). Compared to driving cycle emissions HC emissions duringidling is reported to be 1 to 5 times more than that of driving cycleand idling CO emissions were 5e75% of driving emissions(McCormick et al., 2000). The study of Roy et al. (2013) was basedupon biodiesel produced from Canola oil. But since canola oil is anedible oil, so using biodiesel produced from canola oil will be amenace to food security. As the world confronts a reported foodshortage and rising fuel prices, researchers are looking for feed-stock that would not affect food security. It is becoming increas-ingly apparent that the demand for biodiesel is going to increase innear future. Albeit many edible oils might be the inexpensivefeedstock for biodiesel production, but most of them are not asustainable source to meet this increasing demand. This sub-stantiates the necessity to use non-edible oil feedstock for biodieselproduction. In this perspective, Jatropha oil is a promising non-edible feedstock. It will not pose a threat to food security. Thus, ithas gained popularity as a prospective substitute of diesel fuel andmany studies have been conducted to evaluate engine performanceusing Jatropha biodiesel blends in a diesel engine (Ong et al., 2013;Palash et al., 2014; Rahman et al., 2013; Sanjid et al., 2013). How-ever, no study was done to evaluate its performance during idling.So, the main objectives of this study are-

a) Characterization of Jatropha biodiesel properties in order tocompare with ASTM standards

b) Study of effect of Jatropha biodiesel blends on fuel consumptionat high idling conditions

c) Study of effect of Jatropha biodiesel blends on engine emissionsconditions at high idling conditions

s % of total taxes and social contributions.


Fig. 2. Environmental taxes by tax category.

S.M.A. Rahman et al. / Journal of Cleaner Production xxx (2014) 1e8 3

2. Biodiesel property test

Jatropha biodiesel (JB100) properties were measured in theEnergy Laboratory and the Engine Tribology Laboratory, Depart-ment of Mechanical Engineering, University of Malaya. Propertytesting equipment and method are listed in Table 1 and themeasured fuel properties are given in Table 2.

3. Engine test

The engine test was done with an in-line four cylinder CI enginewhich was coupled with an eddy current dynamometer. Threeidling conditions (1000 RPM 10% load, 1200 RPM 12% load and1500 RPM 15% load) were considered in this investigation. 10% and20% (JB10 and JB20) blends of Jatropha along with diesel fuel havebeen used to run the engine. Also, to depict the effect of idling,engine was run at 100% load at 2000 RPM and measured data werecompared with the idling data. Schematic diagram of the enginesetup is given in Fig. 3. Tables 3 and 4 shows engine specificationand test equipment respectively. For combustion analysis a pres-sure sensor and a crank angle encoder (RIE-360) have been used.These two sensors together provides the in-cylinder pressurevariation with crank angle. Digital data have been recorded in acomputer using a software name DEWESoft Combustion Analyzer.

4. Results

Fig. 4 shows CO emissions at different idling conditions fordiesel and Jatropha biodiesel blends. The lowest CO emissions areachieved for JB20 at all the operating conditions. Also, in every

Table 1List of equipment used for fuel properties testing.

Property Equipment Test method

Kinematic viscosity SVM 3000 (Anton Paar, UK) ASTM D445Flash point Pensky-martens flash point -

automatic NPM 440 (Norma lab,France)

ASTM D93

Oxidation stability 873 Rancimat (Metrohm, Switzerland) EN ISO 14112Cloud and pour point Cloud and Pour point tester e

automatic NTE 450 (Norma lab,France)

ASTM D2500ASTM D97

CCR Micro-Carbone Conradson ResidueTester e automatic NMC 440(Norma lab, France)

ASTM D4530

Total sulfur Multi EA 5000 (Analytical Jena,Germany)

ASTM D5433

Density SVM 3000 (Anton Paar, UK) ASTM D1298Caloric value C2000 basic calorimeter (IKA, UK) ASTM D240


condition diesel fuel produced maximum emissions. As blendpercentage of biodiesel in diesel increased emissions decreased.

Fig. 5 represents HC emissions at different idling conditions fordiesel and Jatropha biodiesel. It can be seen that, diesel fuel emitshighest amount of HC at all conditions and 20% Jatropha biodieselblends emits lowest.

Furthermore, it is seen that increase in idling speed decreasesHC emissions for all tested fuel.

Fig. 6 demonstrates NOX emissions at different idling conditionsfor diesel and Jatropha biodiesel blends. Diesel fuel exhibitedlowest emissions at all condition. As blend percentages of biodieselincreases emissions increases. JB20 emitted highest NOX emissions.Also it is evident that increase in idling speed reduces NOXemissions.

Fig. 7 shows the fuel consumption at different idling conditionsfor diesel and Jatropha biodiesel blends. At all conditions diesel fuelconsumption rate was lowest, and as blend percentages increasedfuel consumption increased. JB20 biodiesel blends fuel consump-tion were highest at all conditions.

Fig. 8 depicts in-cylinder pressure at various crank angle ofJatropha biodiesels at all idling modes. From the figures it can beseen that, maximum in-cylinder pressure for diesel fuel at all idlingmodes are lowest compared to Jatropha biodieselediesel blends.With increase in blend percentages of Jatropha biodiesel in diesel,cylinder pressure increases for all the idling modes.

5. Discussion

During this time, the engine can not work at peak operatingtemperature. This leads to incomplete combustion and emissionslevel increase due to having fuel residues in the exhaust. Also, idlingresults in increase in fuel consumption. One of the main factor of

Table 2Major physico-chemical properties of the diesel and jatropha.

Properties Units Standards ASTM D6751 Jatropha Diesel

Kinematicviscosityat 40 �C

mm2/s ASTM D445 1.9e6 4.7227 3.46

Density at 15 �C kg/m3 ASTM D1298 860e900 865 833.1Flash point �C ASTM D93 >130 182.5 77Cloud point �C ASTM D2500 �3 to 12 5 8Pour point �C ASTM D97 �15 to 10 3 6Calorific value

(Lower heatingvalue)

MJ/kg ASTM D240 e 39.8 44.664

Iodine value g I/100 g EN 14111 120 max 99 e

Acid value mg KOH/g ASTM D664 0.8 max 0.05 e

Oxidation stability h EN ISO 14112 3 min 3.7 110Cetane number e ASTM D613 47 min 52 48


Fig. 3. Schematic diagram of the engine test bed.


increase in HC emissions is at light idle and load is over mixing,especially for engines of a relatively small size at high speed.Incomplete oxidation product of fuel carbon results in CarbonMonoxide (CO) emissions. Generally CO formation is resulted fromincomplete combustion. Incomplete combustion occurs whenflame front approaches to crevice volume and relatively cool cyl-inder liner.

From Fig. 4, increase in percentage of biodiesel in blend,decreased CO emission. These may be due to the higher concen-tration of O2 in the air-fuel mixture which ensured improvedcombustion and hence reduction in CO emissions at idling condi-tions. Also, due to these reason, HC emissions decreases with in-crease in blend percentageswhich can be seen from Fig. 5. Decreasein HC emission with increase in idling speed is due to the reasonthat increase in speed ensures better mixing of air and fuel. COemission at idling mode 1 for diesel, JB10 and JB20 was 22.43 g/h,18.80 g/h and 16.55 g/h respectively. The reduction of CO emissiondue to use of biodiesel was 16.18% and 26.2% respectively for JB10and JB20. CO emission at idlingmode 2 for diesel, JB10 and JB20was19.77 g/h, 17.03 g/h and 15.36 g/h respectively. The reduction of COemission due to use of biodiesel was 13.9% and 22.3% respectivelyfor JB10 and JB20. CO emission at idling mode 3 for diesel, JB10 andJB20 was 17.29 g/h, 14.49 g/h and 10.12 g/h respectively. Thereduction of CO emission due to use of biodiesel was 16.7% and41.46% respectively for JB10 and JB20. The reduction of HC emis-sions due to use of biodiesel was at idling mode 1e4% and 36.36%,at idling mode 2e11.11% and 42%, at idling mode 3e2.37% and 44%respectively for JB10 and JB20. As increase in blend percentages alsomeans additional oxygen content of the biodiesel facilitate bettercombustion. Similar trends were observed in the study of Roy et al.(2013), where the author reported that canola oil biodiesel blendsdecreased CO emissions compared to diesel fuel at high idlingconditions. Canola biodieselediesel blends exhibited similarreduction of HC, however, achieved lower CO emissions reductioncompared to Jatropha biodiesel blends used in this study. Reductionof CO and HC emissions also supported by other researchers

Table 3Engine specification.

Engine type 4 cylinder inlineDisplacement 2.5 L (2476 cc)Bore 91.1 mmStroke 95.0 mmInjection system Direct, naturally aspiratedTorque Max. 132 N-m, at 2000 rpmPower Max 50 kW at 4000 rpmCompression ratio 21:1Injection pump Common rail mechanically controlled


(Lakshmi Narayana Rao et al., 2007; Narayana Reddy and Ramesh,2006). Compared to engine running at 100% load and 2000 RPM,CO emissions for diesel, JB10 and JB20 at three idling modes were39.29e50.97%, 36.84e47.8% and 27.59e45.12% respectively.Compared to engine running at 100% load and 2000 RPM, HCemissions for diesel, JB10 and JB20 at three idling modes were44.55e53.67%, 44.48e52.67% and 31e42.7% respectively.

From Fig. 6, compared to diesel fuel, biodiesel blends producedhigher NOx emissions. NOx emission at idling mode 1 for diesel,JB10 and JB20 was 1.54 g/h, 1.72 g/h and 1.869 g/h respectively. Theincrease of NOx emission due to use of biodiesel was 11.7% and21.36% respectively for JB10 and JB20. NOx emission at idling mode2 for diesel, JB10 and JB20 was 1.464 g/h, 1.64 g/h and 1.807 g/hrespectively. The increase of NOx emission due to use of biodieselwas 12.02% and 23.42% respectively for JB10 and JB20. NOx emissionat idling mode 3 for diesel, JB10 and JB20 was 1.185 g/h, 1.339 g/hand 1.573 g/h respectively. The increase of NOx emission due to useof biodiesel was 13% and 32.74% respectively for JB10 and JB20. So, itis clearly evident that, increase in biodiesel percentages signifi-cantly increases NOx emissions, these trends are supported byLapuerta et al. (2008a,b). Biodiesels have higher cetane number andthus lower ignition delay (Robbins et al., 2009). A shorter ignitiondelay could allow the fuel mixture and initial combustion productsto have a longer residence time at elevated temperature, therebyincreasing thermal NOx formation Biodiesel reduces soot concen-tration. Soot particles reduces chamber temperature throughradiative heat transfer. Thus decreasing soot particles results inhigher combustion chamber temperature thus increases NOx

emissions (Hoekman and Robbins, 2012; Mueller et al., 2009).However, it is observed that, the higher the speed, the lower theNOx emissions. This may be attributed to the shorter residencetime/ignition delay available for NOx formation at higher speeds(Lin and Li, 2009). Also, increase in NOx emissions with increase ofpercentages of biodiesel in blends is due to the reason that bio-diesel have higher oxygen contents compare to diesel fuel (Hansenet al., 2006; Ozsezen et al., 2009). Roy et al. (2013) reported that,

Table 4Equipment used in engine test.

Equipment name BOSCH BEA-350 exhaust gas analyzerMeasured HC (parts per million or ppm)

Carbon monoxide (percentage volume or %vol)Carbon dioxide (percentage volume or %vol)

Equipment name AVL 4000 (Manufacturer: Graz/Austria)Measured NOx (parts per million or ppm)Equipment Name DYNOMAX 2000 data control systemMeasured Exhaust gas temperature (EGT)

Fuel consumption


Fig. 6. NOx emissions at different idling conditions and at 100% load, 2000 RPM fordiesel and Jatropha biodiesel blend.

Fig. 4. CO emissions at different idling conditions and at 100% load, 2000 RPM fordiesel and Jatropha biodiesel blend.


lower percentages of canola biodiesel in blends exhibited almostnegligible increase in NOx emission compared to diesel fuel, how-ever as blend percentage increased emissions increase significantly,20% Canola biodiesel blend, emitted almost 30e50% more NOx

compared to diesel fuel at all condition. Similar trend is also seen inthis study. Also, increase in NOx emissions due to use of Jatrophabiodiesel is supported by Lakshmi Narayana Rao et al. (2007).Compared to engine running at 100% load and 2000 RPM, NOx

emissions for diesel, JB10 and JB20 at three idling modes were41.34e53.73%, 45e58% and 51.73e61.5% respectively.

Biodiesel have lower heating value compared to diesel fuel.From Table 2, it is seen that Jatropha biodiesel have lower calorificvalue of 39.8 MJ/kg whereas Diesel fuel have 44.664 MJ/kg.Compared to diesel fuel, which is almost 11% less. Due to thisreason, Jatropha biodiesel diesel blends have less calorific value.Thus fuel consumption increases. Fuel consumption also increasedwith rising idling speed. According to Lim, when an engine is idlingat a faster speed, fuel consumptionwill be higher due to an increasein the fuel injection rate per second (Lim, 2002). Increase in fuelconsumption for JB10 and JB20 for idling mode 1 was 21.05% and26.3%, for idling mode 2 was 17.4% and 26.1% and for idling mode 3was 3.33% and 6.66% respectively. So, it is clearly evident that, in-crease in idling speed results in somewhat better combustion thus,increase in fuel consumption is significantly reducing with speed

Fig. 5. HC emissions at different idling conditions and at 100% load, 2000 RPM fordiesel and Jatropha biodiesel blend.


due to use of Jatropha biodiesel blends. Compared to enginerunning at 100% load and 2000 RPM, fuel consumption for diesel,JB10 and JB20 at three idling modes were 35e44%, 38.5e48% and41.2e51.4% respectively.

When the engine is running at low load, residual gas tempera-ture and wall temperature are low. Therefore, injection chargetemperatures are also significantly low, which in turns increasesinjection delay period. Thus for diesel fuel combustion starts latercompared to biodiesel and its blends, and thus have a lower peakpressure compared to biodiesel blends. Consequently, for dieselfuel, the peak cylinder pressure reaches a lesser value further awayfrom the top dead center in the expansion stroke. Again, for bio-diesel and its blends peak cylinder pressure take place earlier.These trends are observed in Fig. 8. For idling mode 1, peak cylinderpressure for diesel, JB10 and JB20 were 53.7 bar 55.9 bar and56.8 bar respectively, whereas, for idling mode 2, they were60.7 bar, 61.1 bar and 62.5 bar respectively. And, for idling mode 3,the values were 62.9 bar, 63.1 bar and 64.8 bar for diesel, JB10 andJB20 respectively.

Also, all the results found from this study is within the rangereported in several literature (Brodrick et al., 2002; Lim, 2002;Storey et al., 2003).

Fig. 7. Fuel consumption at different idling conditions and at 100% load, 2000 RPM fordiesel and Jatropha biodiesel blend.


Fig. 8. In-cylinder pressure vs. crank angle variation of Jatropha biodiesel blends compared to diesel at a) idling mode 1 b) idling mode 2 and c) idling mode 3.


6. Recommendation-alternatives of idling

The use of some technical applications (such as vehicle’s battery,Direct fire heater etc.) offer substitutes to engine idling (Frey et al.,2001; Pfaff et al., 2011). The vehicle’s battery power could be pre-sented as the first alternate, but they might become stressedthrough protracted use. Another option is direct fire heaters (DFHs),whichmaintain a supply of heat to the cabin and consume a smalleramount of fuel for heating the cab/sleeper However, DFHs do notprovide power to any other accessories. Thermal storage systems(TSSs) use the thermal energy conveyed from the engine or airconditioner during the vehicle’s operation. This energy is stored ina phase-change material. TSSs can supply both cooling and heatingof the cabin. Auxiliary power units (APUs) are the internal-combustion engine, which also consists of heat recovery and agenerator to provide heat and electricity (Baratto et al., 2005). APUsdo not replace the original engine but compliment it by offeringlow emissions, high comforts, and low fuel consumption whileidling. There are many types of APUs, such as diesel internal-combustion engine (Hoekman et al., 2012). APUs, battery electricAPUs, diesel fuel cell APUs, etc. Diesel ICE and battery electric APUscan be great substitutes to idling. The one major drawback of bat-tery APUs is that they are not able to store and deliver the equiv-alent power that is available from diesel ICE APUs. When the truckis parked, compared with diesel ICE and battery APUs, the dieselfuel cell APUs can provide auxiliary power at higher efficiency. Inaddition, the efficiency of the APU compared with the combinationof the diesel engine and the alternator, is much higher. These sys-tems can also supply the vehicle with auxiliary power when


running, which means that the energy efficiency will increaseoverall (Soberanes et al., 2012). Among the various fuel cellsavailable, only solid oxide fuel cells (SOFCs) and proton exchangemembrane fuel cells (PEMFCs) are most suited as on-board APUs(Agnolucci, 2007; Lawrence and Boltze, 2006). For fuel cell APUs,30% fuel efficiency has been reported in the literature (Lawrenceand Boltze, 2006). Fuel cell APUs can reduce both the fuel con-sumption of trucks and the emissions of pollutants substantially. Acompletely different approach is seen in the scenario of truck stopelectrification (TSE). To power the non-propulsion requirements ata truck-stop, the trucks are simply “plugged in” to the outlets. Thisallows operation of on-board systems, such as sleeper cab cooling,heating, microwave ovens, televisions, refrigerators, and othersmall appliances when parked without the need for idling (Jainet al., 2006; Zietsman et al., 2005). If truck stop electrification isutilized properly, it can reduce fuel consumption during idlingsubstantially or eventually, eliminate it altogether. An inverterconverts the truck’s 12 V battery direct current (DC) power into120 V alternative power for cab appliances and accessories. How-ever, the main problem with inverters is that they can not supplyhigh-power-draw devices, such as an air conditioner or heater foran extended period of time (Perrot et al., 2004). Noise, additionalmaintenance, and deterioration of the engine are the major dis-advantages of APUs. The disadvantages of DFHs are their inability toprovide cooling and the amount of use required of the trucks’battery, while the disadvantages of fuel cells are the absence ofappropriate fuels, higher production expenses of the units, and theintegration of the units with other on-board truck systems. TSE alsohas significant disadvantages, which comprise the cost of the



equipment and accessibility, because the use of the system isrestricted to truck stops (Hafiz et al., 2007).

7. Conclusions

An experimental investigation has been carried out to figure outthe fuel consumption and emissions parameters at high idlingconditions. The most important conclusions derived are summa-rized as follows:

� Fuel consumption e At high idling conditions brake specificfuel consumption for Jatropha biodiesel blends increasedcompare to diesel fuel. As blend percentages of biodieselincreased fuel consumption increased. Increase in fuel con-sumption for JB10 and JB20 for idling mode 1 were 21.05% and26.3%, for idling mode 2 were 17.4% and 26.1% and for idlingmode 3 were 3.33% and 6.66% respectively. Compared to enginerunning at 100% load and 2000 RPM, fuel consumption fordiesel, JB10 and JB20 at three idling modes were 35e44%, 38.5e48% and 41.2e51.4% respectively.

� CO emissions e CO emissions decreased with increase in blendpercentages and at all tested conditions they were lower thandiesel fuel. CO emission at idling mode 1 for diesel, JB10 andJB20 was 22.43 g/h, 18.80 g/h and 16.55 g/h respectively. Thereduction of CO emission due to use of biodiesel was 16.18% and26.2% respectively for JB10 and JB20. CO emission at idling mode2 for diesel, JB10 and JB20 was 19.77 g/h, 17.03 g/h and 15.36 g/hrespectively. The reduction of CO emission due to use of bio-diesel was 13.9% and 22.3% respectively for JB10 and JB20. COemission at idlingmode 3 for diesel, JB10 and JB20was 17.29 g/h,14.49 g/h and 10.12 g/h respectively. The reduction of COemission due to use of biodiesel was 16.7% and 41.46% respec-tively for JB10 and JB20. Compared to engine running at 100%load and 2000 RPM, CO emissions for diesel, JB10 and JB20 atthree idling modes were 39.29e50.97%, 36.84e47.8% and27.59e45.12% respectively.

� HC emissions e HC emissions decreased with increase in blendpercentages and at all tested conditions they were lower thandiesel fuel The reduction of HC emissions due to use of biodieselwasat idlingmode1e4%and36.36%, at idlingmode2e11.11%and42%, at idling mode 3e2.37% and 44% respectively for JB10 andJB20. Compared to engine running at 100% load and 2000 RPM,HC emissions for diesel, JB10 and JB20 at three idlingmodeswere44.55e53.67%, 44.48e52.67% and 31e42.7% respectively.

� NOx emissions e NOx emission at idling mode 1 for diesel, JB10and JB20 was 1.54 g/h, 1.72 g/h and 1.869 g/h respectively. Theincrease of NOX emission due to use of biodiesel was 11.7% and21.36% respectively for JB10 and JB20. NOx emission at idlingmode 2 for diesel, JB10 and JB20 was 1.464 g/h, 1.64 g/h and1.807 g/h respectively. The increase of NOx emission due to useof biodiesel was 12.02% and 23.42% respectively for JB10 andJB20. NOx emission at idlingmode 3 for diesel, JB10 and JB20was1.185 g/h, 1.339 g/h and 1.573 g/h respectively. The increase ofNOx emission due to use of biodiesel was 13% and 32.74%respectively for JB10 and JB20. As blend percentages increasedto NOx emissions increased significantly. Also, with increase inidling speed NOx emissions decreased, due to shorter residencetime/ignition delay available for NOx formation at higher speeds.Compared to engine running at 100% load and 2000 RPM, NOx

emissions for diesel, JB10 and JB20 at three idling modes were41.34e53.73%, 45e58% and 51.73e61.5% respectively.

The increasing motorization throughout the world has intensi-fied the demand of fossil fuel which has led clean environment inperil. The harmful exhaust emissions from the engines, rapid


increase in the prices of petroleum products, and uncertainties oftheir supply have jointly created renewed interest among the re-searchers to search for suitable alternative fuels. Most of the oilsused for the production of biodiesel by various researchers weresoybean, sunflower, safflower, cotton, and rapeseed. These oils areessentially edible oil. Using edible oils to produce biodiesel mayresult a dearth of food. Thus, biodiesel produced fromnon-edible oilis currently getting momentum throughout the world. Jatrophacurcas is one such kind of non-edible feedstock. Thus, this can beused to produce biodiesel. From this study, it has been explicit that,during idling condition, use of Jatropha biodieselediesel blendsmakes a conspicuous improvement CO and HC emissions. However,fuel consumption andNOxemissionsmarginally degenerates duringidling. Thus, it can be recommended that, Jatropha biodieseledieselblend can slightly improve engines performance during idling thuscan be used to operate a diesel engine.

Acknowledgments

The authors would like to appreciate University of Malaya forfinancial support through High Impact Research grant titled: CleanDiesel Technology for Military and Civilian Transport Vehicleshaving grant number UM.C/HIR/MOHE/ENG/07.

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