Assessment of performance, emission and combustion characteristics of palm, jatropha and Calophyllum inophyllum biodiesel blends

Fuel xxx (2016) xxx–xxx

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Full Length Article

Assessment of performance, emission and combustion characteristics of palm, jatropha and Calophyllum inophyllum biodiesel blends I.M. Monirul a,⇑, H.H. Masjuki a, M.A. Kalam a,⇑, M.H. Mosarof a,⇑, N.W.M. Zulkifli a, Y.H. Teoh a,b, H.G. How a a b

Center for Energy Science, Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia School of Mechanical Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang, Malaysia

h i g h l i g h t s
All of biodiesel blends showed almost 7.5% higher BSFC than diesel fuel.
Diesel produces higher BP and BTE compared to biodiesel blends.
JB20 produced 7.49% and 14.90% lower CO and HC emissions compared to diesel.
JB10 produced 31.79% lower amount of smoke opacity than diesel fuel.
PB20 has lower emission and better engine performance than diesel fuel.

a r t i c l e

i n f o

Article history: Received 11 January 2016 Received in revised form 26 March 2016 Accepted 4 May 2016 Available online xxxx Keywords: Renewable energy Diesel engine Biodiesel Performance Emission and combustion

a b s t r a c t Biodiesel is an alternative diesel fuel that is produced from renewable resources. Energy studies conducted over the last two decades focused on solutions to problems of rising fossil fuel price, increasing dependency on foreign energy sources, and environmental concerns. Palm oil biodiesel is mostly used in Malaysia. Engine performance and emission tests were conducted with a single-cylinder diesel engine fueled with palm, jatropha and Calophyllum inophyllum biodiesel blends (PB10, PB20, JB10, JB20, CIB10, and CIB20) and then compared with diesel fuel at a full-load engine speed range of 1000–2400 rpm. The average brake specific fuel consumption increased from 7.96% to 10.15% while operating on 10%, and 20%, blends of palm, jatropha and C. inophyllum biodiesel. The average brake power for PB10 and PB20 were 9.31% and 12.93% lower respectively compared with that for diesel fuel. JB10 showed higher amount of brake specific fuel consumption than diesel and other biodiesel blends. PB20 produces comparatively lower CO and HC emissions than diesel and biodiesel blends. JB10 showed 31.09% lower smoke opacity than diesel fuel. Diesel produces lower amount of NOX emission compared to biodiesel blends. The higher peak cylinder pressure and heat release rate were found with CIB blends compared to diesel fuel, palm and jatropha biodiesel blends. Results indicated that PB20 has better engine performance, and lower emission compared with diesel and biodiesel blends. Thus, PB20 is suitable for use in diesel engines without the need for any engine modification. Ó 2016 Elsevier Ltd. All rights reserved.

1. Introduction Nowadays, biodiesel plays an important role in helping overcome oil shortages and mitigating environmental effects in petroleum fuel fields worldwide [1]. Energy consumption has increased because of the wide use of fossil fuels in power plants, transportation vehicles, electric generators, mining equipment, and locomotives [2,3]. Prices of fossil fuels, such as coal, gas, and petroleum,

⇑ Corresponding authors. E-mail addresses: [email protected] (I.M. Monirul), [email protected]. my (M.A. Kalam), [email protected] (M.H. Mosarof).

are rising day by day [4]. Biodiesel is used as an alternative diesel fuel in transport vehicles and is produced from edible and nonedible vegetable oils [5]. It is biodegradable, oxygenated, nontoxic, sulfur-free, sustainable, renewable, and can be used in diesel engines, either in pure form or blended with diesel without any engine modification [6–9]. The use of fossil fuels, which produce high amounts of greenhouse gas emissions, can increase environmental pollution. Rail and road traffic produce more noise that can affect human health. In the European Union, 20% of the population suffers from this type of noise [10]. Moreover, many researchers observed that biodiesel shows low regulated and unregulated emissions [3,11]. Using biodiesel in diesel engines can reduce

http://dx.doi.org/10.1016/j.fuel.2016.05.010 0016-2361/Ó 2016 Elsevier Ltd. All rights reserved.

Please cite this article in press as: Monirul IM et al. Assessment of performance, emission and combustion characteristics of palm, jatropha and Calophyllum inophyllum biodiesel blends. Fuel (2016), http://dx.doi.org/10.1016/j.fuel.2016.05.010

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I.M. Monirul et al. / Fuel xxx (2016) xxx–xxx

Nomenclature BP BSFC BTE CIB CIME FAC

brake power brake specific fuel consumption brake thermal efficiency Calophyllum inophyllum biodiesel Calophyllum inophyllum methyl ester fatty acid composition

harmful emissions, such as carbon monoxide, carbon dioxide, unburned hydrocarbon, and particulate matters [12–14]. The parameters of diesel engine performance, such as brake specific fuel consumption (BSFC), brake power (BP), brake torque, and brake thermal efficiency, must be improved to reduce emissions [13,15,16]. Fuel injection systems have played a vital role in improving fuel economy and reducing engine emissions. In injection systems, injection timing, injection duration, fueling, and injection pressure are the most important parameters that adversely affect engine performance and emissions [17,18]. Low emissions and high engine performance can be attained by recirculating exhaust gasses [19]. In diesel engines, various sliding engine parts produce more friction between the metal contact surfaces, which reduces engine reliability. Lubricity is one of the most important factors in extending engine life [20]. Lubrication is needed to reduce friction and wear between the engine sliding parts. Generally, fuel lubricity depends on dynamic viscosity, which is the function of temperature, pressure, density, and viscosity [21]. Engine components such as fuel pump, piston–cylinder liner, fuel injector, fuel depositors, and piston rings produce more friction; hence, these components require lubrication to reduce friction [22]. Carbon particle deposition, high viscosity and density, unsaturated fatty acid composition, corrosive nature, injector coking, and filter plugging are the main drawbacks of the lubrication effect [23]. Nevertheless, biodiesel provides better engine performance, lubricating performance, and lower emissions compared with diesel fuel. Ozsezen and Canakci [24] observed the performance and emission of palm biodiesel that filled a six-cylinder diesel engine. They observed that BP decreased about 2.5% and BSFC increased about 7.5%. Palm biodiesel had lower HC (14.29%), CO (86.89%), and smoke (67.65%) emissions but a high amount of NOX (22.13%) emission compared with diesel fuel. When diesel and palm biodiesel blends fueled in a KIR-LOSKAR TV-1 type four-stroke diesel engine with varying loads of 20–100% at a constant speed (800 rpm) and full-load condition, BSFC showed for pure palm biodiesel and diesel fuel were 0.2749 and 3.31491 kg/kW h respectively. BSFC of 25%, 50%, and 75% palm biodiesel blends observed to be 2.59%, 8.93%, and 9.25% higher compared with those of diesel fuel [25]. Dorado et al. [26] reported that biodiesel blends showed slightly lower BSFC compared to ordinary diesel fuel. The effects of injector deposits, filter plugging, corrosion, and piston pump wear could be caused by oxidation stability in diesel and biodiesel [27]. Liaquat et al. [28], observed exhaust emissions for palm oil biodiesel used in a four-stroke DI diesel engine. The engine exhaust emissions were observed by a BOSCH gas analyzer, and the test was conducted on a 250 h engine speed at 2000 rpm. CO and CO2 emissions decreased with increasing percentage of biodiesel in the blend. Diesel was given a higher amount of HC compared with palm biodiesel at full- and middle-load conditions [29]. Ong et al. [30], observed single-cylinder diesel engine performance and exhaust emissions within fueled high free fatty acid Calophyllum inophyllum biodiesel blends. CIB10 showed highest BTE and good engine performance. BSFC and EGT of CIB10 showed lower engine performance compared with diesel fuel. CIB10 reduced CO and

FAME GC JB JOME PB POME

fatty acid methyl ester gas chromatography jatropha biodiesel jatropha oil methyl ester palm biodiesel palm oil methyl ester

smoke emission, although a slightly higher NOX emission was observed compared with diesel fuel. Adding some additives with CI biodiesel blends also reduced NOX emission [12]. Many researchers have investigated and compared palm and jatropha biodiesel blends with diesel fuel, whereas other studies compared palm and Calophyllum inophyllum (C. inophyllum) biodiesel blends with diesel fuel [13,31]. However, no study has been conducted that compares palm, jatropha, and C. inophyllum biodiesel blends with diesel fuel. The aim of this study, to observe the performance, emissions and combustion characteristics of a diesel engine by using palm, jatropha, and C. inophyllum biodiesel blends and also compare them. Finally, evaluating which biodiesel blend has better engine performance, lower emissions and combustion characteristics. 2. Materials and methods 2.1. Biodiesel production and blends The crude palm oil collected from a Malaysian local market and crude C. inophyllum and jatropha oil were collected from a foreign supplier. The transesterification process was used to produce palm and CI biodiesel. Crude palm, jatropha and C. inophyllum oil were mixed with 25% methanol (V/V) and 1% KOH (w/w). In this process, the chemical reaction was obtained within 2 h by the maintaining a constant temperature of 60 °C and stirring speed of 1000 rpm. After the first step was completed, biodiesel was poured into a funnel to separate glycerin from biodiesel; the whole separation process took 12 h. After the reaction was completed, the lower layer was drawn off because it contained glycerin and some impurities. The methyl ester was washed with distilled water to remove the impurities. Distilled water (50% V/V) was sprayed over the esters at 60 °C. This process was repeated several times until all impurities from the methyl ester were completely removed. Then, methyl ester was dried with a rotary evaporator and filtered using filter paper. After all the steps were completed, the final product was collected for the experiment. POME, JOME and CIME were mixed with diesel to produce biodiesel blends. Three types of biodiesel blends were produced for palm and CI biodiesel, including PB10 (10% POME + 90% diesel), PB20 (20% POME + 80% diesel), JB10 (10% JOME + 90% diesel), JB20 (20% JOME + 80% diesel), CIB10 (10% CIME + 90% diesel), and CIB20 (20% CIME + 80% diesel). A total of six biodiesel blends and diesel were used in this experiment. 2.2. Fatty acid composition of biodiesel methyl ester Gas chromatography (GC) was used to measure fatty acid composition of POME, JOME and CIME. This instrument shows fatty acid composition results in weight percentage. Fatty acid compositions of POME, JOME and CIME are shown in Table 1. For FAC analysis, 0.02 g of biodiesel was diluted with 1.5 ml hexane in a small vial; the diluted sample was charged with a flame ionization detector within 2 ll, which was connected by Perkin-Elmer GC. Then, each peak was identified and compared with the standard value

Please cite this article in press as: Monirul IM et al. Assessment of performance, emission and combustion characteristics of palm, jatropha and Calophyllum inophyllum biodiesel blends. Fuel (2016), http://dx.doi.org/10.1016/j.fuel.2016.05.010

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I.M. Monirul et al. / Fuel xxx (2016) xxx–xxx Table 1 POME, JOME and CIME fatty acid composition by percentage of weight. FAME name

Carbon structure

Chemical formula

Molecular mass

Methyl laurate Methyl myristate Methyl palmitate Methyl palmitoleate Methyl stearate Methyl oleate Methyl linoleate Methyl linolenate Methyl archidate Methyl eicosenoate Methyl behenate Methyl lignocerate Saturated Mono-saturated Polyunsaturated

12:00 14:00 16:00 16:01 18:00 18:01 18:02 18:03 20:00 20:01 22:00 24:0 – – –

CH3(CH2)10COOCH3 CH3(CH2)12COOCH3 CH3(CH2)14COOCH3 CH3(CH2)5CH@CH(CH2)7COOCH3 CH3(CH2)16CO2CH3 CH3(CH2)7CH@CH(CH2)7COOCH3 CH3(CH2)3(CH2CH@CH)2(CH2)7COOCH3 CH2(CH2CH@CH)3(CH2)7COOCH3 CH3(CH2)18COOCH3 CH3(CH2)16CH@CHCOOCH3 CH3(CH2)20COOCH3 CH3(CH2)22COOCH3 – – –

214.34 242.4 270.45 268.43 298.5 296.49 294.47 292.46 326.56 324.54 354.61 382.66 – – –

of FAC. The absolute FAC value was calculated by adding the identified peak value, and FAME was also calculated using this value. POME consists of seven saturated (44.3%), three monounsaturated (44.2%), and two polyunsaturated (11.5%) fatty acid compositions. JOME consists of four saturated (23.9%), two monounsaturated (42.8%), and two polyunsaturated (32.9%) fatty acid composition. By contrast, CIME contains four saturated (34.6%) and six unsaturated (63.4%) fatty acid compositions. 2.3. Properties of biodiesel and its blends The physical and chemical properties of palm, jatropha and CI biodiesel blends, such as viscosity, density, viscosity index, cloud point, flash point, pour point, oxidation stability, acid value, cetane index, and calorific value, were measured according to ASTM standard methods. Table 2 shows the synopsis of equipment and test methods used to determine fuel properties. Physical and chemical properties of diesel, palm, jatropha and CI biodiesel blends (PB10, PB20, JB10, JB20, CIB10, and CIB20) are shown in Table 3. Density (40 °C), dynamic viscosity (40 °C), and kinematic viscosity (40 °C and 100 °C) were measured using Stabinger Viscometer (model SVM 3000, Anton Paar, UK). A bomb calorimeter (model C2000 basic calorimeter, IKA, UK) was used to measure calorific value. The Saponification number and Iodine value were needed for calculating cetane number. The cetane number was calculated by using Eq. (1).

Saponification Number; SN ¼ Iodine Value; Cetane Number;

P 560Ai MW i

P i IV ¼ 254DA  MWi 5458  CN ¼ 46:3 þ SN  ð0:225  IVÞ ð1Þ

Composition (wt.%) POME

JOME

CIME

0.3 0.1 38.4 0.2 4.1 44.3 11.2 0.4 0.4 0.2 0.1 0.1 44.2 44.4 11.4

0 0.1 17.5 0.7 6.2 42.1 32.7 0.2 0.1 0 0 0 23.9 42.8 32.9

0 0 14.7 0.2 17.2 38.2 27.6 0.3 0.9 0.3 0.3 0.1 33.6 38.7 27.6

where Ai is the percentage of each component, D is the double bonds number and MWi is the mass of each component [32]. The molecular mass of each component are shown in Table 1.

2.4. Experimental setup for engine test The experimental test was conducted using a single-cylinder Yammar diesel engine, which is naturally aspirated. The engine speed varied from 1000 rpm to 2400 rpm at full-load condition. Engine specification and operating conditions are shown in Table 4. The schematic diagram of the test engine setup is shown in Fig. 1. The test engine was directly equipped with an Eddy current dynamometer (SAJ SE-20). A strain gauge load cell was used to measure the torque within ±0.25 N m accuracy. Testing oil, engine lube oil, cooling water, inlet air, and exhaust gas temperatures were measured by K-type thermocouple. A Kobold ZOD (positive displacement type) flow meter used to measure the fuel flow rate. Engine performance data were collected using DASTEP8 data acquisition system at a rate of 10 samples per second. Emission parameters such as CO, HC, NOX, and smoke were measured by AVL (model DiCom 4000) exhaust gas analyzer. Exhaust gas analyzer details are shown in Table 5. Initially, the engine was powered with diesel till a steady-state condition was completed; then, the fuel supply was changed to biodiesel blends. After running the engine for 5 min, the residual diesel must be completely removed from the fuel line before data acquisition. This procedure was repeated for each blend. After completing each test, the engine was run again with diesel fuel to drain the biodiesel blend from the fuel line.

Table 2 List of equipments for fuel properties testing. Property

Equipment

Manufacturer

Model

Accuracy

Density Dynamic viscosity Kinematic viscosity Viscosity index Flash point Cloud point Pour point Cold filter plugging point Oxidation stability Calorific value Acid value

Stabinger viscometer Stabinger viscometer Stabinger viscometer Stabinger viscometer Pensky-martens flash point tester Cloud and pourpoint tester Cloud and pour point tester Cold filter plugging point tester Biodiesel Rancimat Basic calorimeter Automated titration system

Anton Paar, UK Anton Paar, UK Anton Paar, UK Anton Paar, UK Norma lab, France Norma lab, France Norma lab, France Norma lab, France Metrohm, Switzerland IKA, UK Mettler Toledo, Switzerland

SVM 3000 SVM 3000 SVM 3000 SVM 3000 NPM 440 NTE 450 NTE 450 NTL 450 873 Rancimat C2000 G-20 Rondolino

±0.1 kg/m3 ±0.1 mm2/s ±0.1 mm2/s ±1 ±0.1 °C ±0.1 °C ±0.1 °C ±0.1 °C ±0.01 h ±0.1% ±0.001 mg KOH/g

Please cite this article in press as: Monirul IM et al. Assessment of performance, emission and combustion characteristics of palm, jatropha and Calophyllum inophyllum biodiesel blends. Fuel (2016), http://dx.doi.org/10.1016/j.fuel.2016.05.010

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Table 3 Physical and chemical properties of palm, jatropha and Calophyllum inophyllum biodiesel blends. Property

Units

Density at 40 °C Dynamic viscosity at 40 °C Kinematic viscosity at 40 °C Kinematic viscosity at 100 °C Viscosity index Oxidation stability Cetane number Cloud point Flash point Pour point Cold filter plugging point Calorific value Acid number

ASTM method

Diesel

PB10

PB20

PB100

JB10

JB20

JB100

CIB10

CIB20

CIB100

kg/m mPa s mm2/s mm2/s – h

D4052 D445 D445 D445 D2270 EN15751

°C °C °C °C MJ/kg mg KOH/g

D2500 D93 D97 D6371 D240 D664

834.7 0.8064 3.4926 1.358 130 35 48 8 68.5 0 5 45.6 0.072

832.6 2.8272 3.3624 1.3261 137 112.48 49 8 76.5 1 6 44.17 0.41

839.5 2.8956 3.4589 1.3479 142 67.36 50 8 77.3 1 7 43.25 0.46

857.6 3.8748 4.3847 1.7656 218 1.03 58 10 181.3 12 11 39.85 0.74

835.8 2.5374 3.7638 1.4371 133 44.8 48 3 87.6 5 5 44.28 0.31

840.5 2.7894 3.8972 1.4822 141 19.20 49 4 93.2 3 4 43.37 0.42

864.6 4.9523 4.7128 1.8025 208 0.06 54 5 183.6 3 3 39.42 0.45

825.6 2.5864 3.7318 1.4485 134 27.70 50 8 72.3 1 7 44.58 0.22

830.3 2.8044 3.7986 1.4786 137 25.19 51 8 73.1 1 6 44.06 0.24

871.8 5.0145 4.9762 1.8314 188 2.53 56 11 92.6 12 9 39.17 0.41

3

2.5. Error analysis

Table 4 Engine specification and operating conditions.

For statistical analysis, two-tailed paired t-test was used for independent variables, which showed a significant difference among the sample set mean values using by Microsoft Excel 2013. Changes among the mean values at a level of p = 0.05 (95% confidence level) were considered statistically significant. Error analysis was needed to determine the percentage of uncertainty and accuracy of experiments. The experimental test results were included with error and uncertainties, which can arise from the selection of instruments, environmental conditions, test conditions, test planning, observation, calibration, and reading. The experimental data were collected at least three times and averaged among them, which performed in graph plotting and precision measuring. Table 6 shows the accuracy of instruments and the relative uncertainty of various test parameters for the experiments. Sample calculations were provided in Appendix A. According to Mofijur et al. [27], the overall uncertainty was calculated at ±3.19% for these experiments. The overall experimental uncertainty was calculated as follows:

Overall uncertainty ¼ Square root of ½ðuncertainty of fuel flow rateÞ þðuncertainty of BSFCÞ

2

2

2

2

þðuncertainty of BPÞ þðuncertainty of BTEÞ 2

þðuncertainty of COÞ þðuncertainty of HCÞ þðuncertainty of NOX Þ

2

2 2

þðuncertainty of smoke opacityÞ  ¼ Square root of ½ð0:4Þ2 þð1:2Þ2 þð0:7Þ2 þð0:8Þ2 þð1:2Þ2 þð1:9Þ2 þð0:7Þ2 þð1:4Þ2  ¼ 3:19%

Engine parameter

Conditions

Model Type

TF 120 M Horizontal, water cooled, single cylinder, four stroke diesel engine 92 mm 96 mm 638 cc 2400 rpm at 7.7 kW, 10.5 Ps

Bore length Stroke length Displacement volume Nominal rated power output Maximum rated power output Size Cooling system Lubricating system Exhaust gas regulation

2400 rpm at 8.8 kW, 12 Ps 695.5 mm  348.5 mm  530 mm Radiator cooling system Completed enclosed forced lubricating system Absence

diesel and other biodiesel blends. PB10, PB20, JB10, JB20, and CIB20 exhibited 3.81%, 7.13%, 7.21%, 12.72%, and 0.51% higher BSFC than diesel fuel, respectively. The average BSFC of the CIB10 blend were 6.98%, 11.60%, and 15.26% lower than diesel, PB10, and JB10, respectively. This result could be attributed by the lower calorific value of the fuel with a higher engine power output [34]. From Fig. 2, when engine was running at low speed, diesel and biodiesel blends showed higher BSFC. The BSFC of biodiesel blends and diesel fuel decreased with the increase in engine speed because of the increasing ratio of fuel atomization [35]. Palm biodiesel blends produced a higher amount of BSFC than jatropha and CI biodiesel blends, except for JB20. For all of biodiesel blends based on the volumetric efficiency, more amount of fuel supply were needed to produce the same engine power output. Higher density and lower calorific value are the main factors for this result. Higher fuel consumption can be caused by the effect of volumetric fuel injection rate with higher viscosity of biodiesel blends [36]. Therefore, CIB10 displays lower specific fuel consumption than other biodiesel blends and diesel fuel.

3. Results and discussion 3.1. Performance characteristics 3.1.1. Brake specific fuel consumption Density, viscosity, higher heating value, calorific value, and volumetric fuel injection are the main factors for the BSFC of diesel engines [33]. Fig. 2 shows the BSFC of biodiesel blends and diesel with variation in engine speed. The average BSFC of biodiesel blends was significantly higher than in diesel fuel except for CIB10. A higher amount of average BSFC was observed in JB20 (0.5915 kg/kW h), the concentrations of which were 4.96% and 10.83% higher than PB20 and CIB20, respectively. A lower amount of average BSFC (0.488 kg/kW h) was determined in CIB10 than in

3.1.2. Brake power The engine BP of different biodiesel blends at different engine speeds are shown in Fig. 3. It was seen from that figure, the engine BP of all fuels gradually increased; when engine speed reached 2200 rpm, BP decreased. The maximum power output for diesel fuel was measured at 5.21 kW at a speed of 2200 rpm. The average BP of diesel were 4.19%, 10.48%, 11.64%, 16.69%, 7.17%, and 11.07% higher than those of PB10, PB20, JB10, JB20, CIB10, and CIB20, respectively. A lower amount of average BP was found with JB20 at 3.63 kW. The average BP of JB20 were 7.445% and 6.75% lower than those of PB20 and CIB20, respectively. JB10 also produced a lower BP than PB10 and CIB10. This result can be caused by the higher heating value of biodiesel blends [37]. The heating value

Please cite this article in press as: Monirul IM et al. Assessment of performance, emission and combustion characteristics of palm, jatropha and Calophyllum inophyllum biodiesel blends. Fuel (2016), http://dx.doi.org/10.1016/j.fuel.2016.05.010

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Fig. 1. Schematic diagram for testing engine.

Table 5 Details for AVL gas analyzer. Parameter

Method

Range

Resolution

Accuracy

CO HC NOX Smoke opacity

Non-dispersive infrared Non-dispersive infrared Electromechanical detector Electromechanical detector

0–10 vol.% 0–20,000 ppm 0–5000 ppm 0–100 vol.%

0.01 vol.% 1 ppm 1 ppm 0.01 vol.%

±0.01 vol.% ±1 ppm ±1 ppm ±0.01 vol.%

Table 6 Summary of the relative uncertainty and accuracy of this experiment. Accuracy

Uncertainty

Fuel flow rate BSFC BP BTE CO HC NOX Smoke opacity

±0.03 l/h ±0.05 g/kW h ±0.02 kW ±0.5 ±0.01 vol.% ±1 ppm ±1 ppm ±0.01 vol.%

±0.4 ±1.2 ±0.7 ±0.8 ±1.2 ±1.9 ±0.7 ±1.4

of JB20 was higher than in other biodiesel blends. Lower density and viscosity of JB20 can affect power loss because of greater leakages in fuel pump compared with other biodiesel blends [38,39]. Fuel containing higher viscosity can reduce fuel pump leakages [40]. Jatropha biodiesel blends produced lower amounts of engine BP than palm and C. inophyllum biodiesel blends. However, diesel fuel showed higher amount of average BP compared with biodiesel blends.

Diesel

BSFC (Kg/Kwh)

Parameters

0.8 0.75 0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25

1000

PB10

1200

PB20

1400

JB10

1600

JB20

CIB10

CIB20

1800

2000

2200

2400

Engine speed (rpm) Fig. 2. Brake specific fuel consumption of diesel and biodiesel blends at various engine loads.

Diesel

PB10

PB20

JB10

JB20

CIB10

CIB20

2000

2200

3.1.3. Brake thermal efficiency Fig. 4 shows the brake thermal efficiency (BTE) of biodiesel blends with variations of engine speed compared to diesel fuel. The maximum amount of BTE was found with CIB10 at 23.2% compared with other biodiesel blends and diesel. The maximum amount of BTE for diesel fuel was 22%. All test fuels showed higher BTE at 2000 rpm. When engine speed was increased to more than 2000 rpm, the BTE of biodiesel blends and diesel decreased simultaneously. The average BTE of diesel, PB10, PB20, JB10, JB20, CIB10, and CIB20 were 18.25%, 17.695%, 17.17%, 16.80%, 15.98%, 18.68%, and 17.58%, respectively. Lower amounts of BTE were observed

Brake power (KW)

6 5 4 3 2 1 0

1000

1200

1400

1600

1800

2400

Engine speed (rpm) Fig. 3. Engine brake power of diesel and biodiesel blends.

Please cite this article in press as: Monirul IM et al. Assessment of performance, emission and combustion characteristics of palm, jatropha and Calophyllum inophyllum biodiesel blends. Fuel (2016), http://dx.doi.org/10.1016/j.fuel.2016.05.010

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I.M. Monirul et al. / Fuel xxx (2016) xxx–xxx Diesel

PB10

PB20

JB10

JB20

CIB10

CIB20

24

BTE (%)

22 20 18 16 14 12 1000

1200

1400

1 600

1800

2 000

2200

2 400

Engine Speed (rpm) Fig. 4. The brake thermal efficiency of diesel and biodiesel blends.

with JB20. The concentrations of JB20 were 7.42% and 10.01% lower than those of PB20 and CIB20, respectively. JB10 also showed lower BTE than PB10 and CIB10. The average BTE of diesel was almost higher than biodiesel blends, except for CIB10. This result can be attributed to the lower calorific value of biodiesel blends with higher fuel consumption. The possibility of higher efficiency can be caused by higher output power and lower BSFC. Lower efficiency of biodiesel blends compared with diesel can be caused by higher density, viscosity, and heating value of biodiesel. Atomization and vaporization of biodiesel blends decreased because of higher viscosity and density, producing uneven combustion characteristics compared with diesel [41]. However, jatropha biodiesel blends showed lower BTE than palm and C. inophyllum biodiesel blends. 3.2. Emission characteristics 3.2.1. CO emission The absence of fuel-borne O2 in the molecular structures of fossil fuel has led to the production of CO emissions [42]. In the combustion process, fuel burning with insufficient air supply and lower temperature could form CO emission. The CO emissions of diesel and biodiesel blends with variations of engine speed are shown in Fig. 5. The lowest amount of CO emissions was produced by PB20 at 1800 rpm and the maximum amount of CO emission was produced by CIB20 at 2400 rpm. Diesel produces lower CO emissions than CIB10 and CIB20 do, approximately 2.33% and 4.70% lower respectively. The average CO emissions of diesel fuel were 2.45%, 4.79%, 1.40%, and 4.29% higher than those of PB10, PB20, JB10, and JB20, respectively. The highest average CO emissions were produced by CIB20. PB20 produced a lower amount of CO emissions than the other biodiesel blends. The average CO emissions of PB20 were 2.45%, 3.56%, 0.52%, 7.49%, and 9.97% lower than those of PB10, JB10, JB20, CIB10, and CIB20, respectively. Palm biodiesel blends produced lower amounts of CO emissions compared to jatropha and C. inophyllum biodiesel blends. These results Diesel

PB10

PB20

JB10

JB20

CIB10

can be caused by the fuel atomization difficulty because of higher viscosity and air–fuel mixture. The CO emission of biodiesel blends was increased with the increased percentage of biodiesel in blend and engine load. If fuel is burned with a rich amount of air–fuel mixture and higher engine load, higher CO emissions will be produced [43]. 3.2.2. HC emission Fuel properties, fuel injection, and engine operating conditions caused the formation of HC emissions [44]. HC emissions for diesel and biodiesel blends are shown in Fig. 6. The average HC emissions of diesel were 10.23%, 13.27%, 7.38%, 14.90% and 10.91% higher than those of PB10, PB20, JB10, JB20 and CIB10 respectively. However, the HC emissions of diesel fuel were lower than those of CIB20 by almost 2.70%. CIB20 showed a higher amount of HC emissions compared to those of diesel and biodiesel blends. JB20 produced lower amount of hydrocarbon (HC) emissions than PB20 and CIB20. The average HC emissions of JB20 were 5.31%, 1.92%, 8.92%, 4.71%, and 18.53% lower than those of PB10, PB20, JB10, CIB10, and CIB20, respectively. HC emissions of all fuels were decreased with increases in engine speed. When engine speed was at the maximum, all fuels showed a lower amount of HC emissions compared to the low engine speed. The average HC emissions of palm and jatropha biodiesel blends were lower than those of C. inophyllum biodiesel blends. For palm biodiesel blends, HC emissions were decreased with increases in biodiesel percentage in the blend. These results could be attributed to the good HC conversion caused by higher cetane number and oxygen content in fuels. Biodiesel has higher oxygen content, which can complete better combustion and reduce HC emissions [45,46]. 3.2.3. NOX emission Fig. 7 shows the NOX emissions for different biodiesel blends with the variations of engine speeds. All biodiesels produce higher amounts of NOX emission than diesel fuel does. The NOX emissions of diesel biodiesel blends were gradually increased with the increases of engine speeds and concentration of biodiesel in blends [47]. Biodiesel has higher oxygen content than diesel fuel, almost 12% higher [48]. These results can be attributed to NOX formation in the combustion process [41,49]. The average NOX emissions of diesel were 4.81%, 8.03%, 1.61%, 5.46%, 6.79%, and 9.42% lower than those of PB10, PB20, JB10, JB20, CIB10, and CIB20 respectively, over engine speeds. The maximum amount of NOX emissions was found with CIB20 at approximately 337.2 ppm at 2400 rpm. CIB20 produces a highest NOX emissions compared with other biodiesel blends. The average NOX emissions of CIB20 were 4.20%, 1.27%, 7.14%, 3.62%, and 2.40% higher than those of PB10, PB20, JB10, JB20, and CIB10, respectively. The low amount of oxidation stability of CIB20 was the main reason for this result. JB10 produced a lower amount of NOX emission than PB10 and CIB10. However, the average NOX emissions of CIB blends were higher than those of PB and JB blends because CI biodiesel blends have higher oxygen

CIB20 Diesel

0.75 0.7 0.65

PB20

JB10

JB20

CIB10

CIB20

50

0.6

HC (ppm)

CO (% Vol)

PB10

60

0.55 0.5 0.45

40 30 20

0.4 10

0.35 0.3

1400

1600

1800

2000

2200

2400

Engine Speed (rpm) Fig. 5. CO emission of diesel and biodiesel blends with variations of engine speed.

0

1400

1600

1800

2000

2200

2400

Engine Speed (rpm) Fig. 6. HC emission of diesel and biodiesel blends with variations of engine speed.

Please cite this article in press as: Monirul IM et al. Assessment of performance, emission and combustion characteristics of palm, jatropha and Calophyllum inophyllum biodiesel blends. Fuel (2016), http://dx.doi.org/10.1016/j.fuel.2016.05.010

7

I.M. Monirul et al. / Fuel xxx (2016) xxx–xxx PB10

PB20

JB10

JB20

CIB10

enrichment of oxygen content in fuel could cause lower smoke opacity for biodiesel blends. Many researchers reported that biodiesel contains oxygen content that can reduce smoke opacity of diesel engine [55–57]. Biodiesel contains aromatic compounds and a lower carbon-to-hydrogen ratio than diesel fuel does, which reduces smoke opacity. The low carbon molecules and oxygen produce soot in fuel and decrease smoke opacity [58]. Diesel contains a high amount of sulfur, which could be attributed to its higher smoke opacity compared with that of biodiesel [59]. Therefore, smoke opacities of biodiesel and diesel fuel depend on the oxygen content, aromatic compounds, and sulfur content.

CIB20

NOX (ppm)

400 350 300 250 200 150

1400

1600

1800

2000

2200

2400

3.3. Combustion analysis

Engine Speed (rpm) Fig. 7. NOX emission of diesel and biodiesel blends with variations of engine speed.

content than PB blends, JB blends and diesel fuel did. In biodiesel blends, NOX emissions were increased because of the increases of _ biodiesel percentages in diesel–biodiesel blends. Ilkılıç and Aydın [50], reported that higher oxygen content of biodiesel blends could raise the temperature and increase the rate of NOX emission formation. The pure biodiesel blends can improve engine combustion because of a higher cetane number of biodiesel, hence forming NOX. Biodiesel contains higher bulk modulus, which leads to early nozzle opening and advanced fuel injection compared to diesel fuel [51,52]. 3.2.4. Smoke opacity Fig. 8 illustrates the variations of smoke opacity for different biodiesel blends with different engine speeds. The smoke opacity indirectly indicates the soot content in exhaust gasses. Diesel gives a higher amount of smoke opacity compared to biodiesel blends, and it was gradually increased with increases of engine speed. The average smoke opacities of diesel at approximately 39.6625 ppm, were 27.45%, 26.34%, 31.79%, 22.28%, 28.08%, and 24.29% higher than those of PB10, PB20, JB10, JB20, CIB10, and CIB20, respectively. JB10 produced the lowest average smoke opacity compared with other biodiesel blends at approximately 27.35 ppm. The average smoke opacity of JB10 were 6.38%, 8.01%, 13.96%, 5.45%, and 11.0% lower than those of PB10, PB20, JB20, CIB10, and CIB20, respectively. Meanwhile, JB20 produced a higher amount of smoke opacity than PB20 and CIB20. The smoke opacity of palm biodiesel blends was gradually increased with increases of engine speed. However, the smoke opacity of jatropha biodiesel blends gradually decreased until 1800 rpm. These also increased with engine speed. The average smoke opacities of jatropha biodiesel blends were lower than those of diesel, palm and C. inophyllum biodiesel blends. These results can be attributed to the presence of higher oxygen contents in jatropha biodiesel compared to diesel, palm and C. inophyllum biodiesel [53]. Xue [54] reported that the Diesel

PB10

PB20

JB10

JB20

CIB10

CIB20

45 40 35 30

TDC

60

Combustion Pressure (bar)

50

Somke opacity

The cylinder combustion pressure and heat release rate of diesel compared with different types of biodiesel blends under a full load condition at engine speed of 1600 rpm are shown in Figs. 9–11 for palm, jatropha, and C. inophyllum biodiesel blends, respectively. For combustion analysis, the peak cylinder pressure is closely correlated with the heating value of fuels and ignition delay. Generally, biodiesel possesses a higher peak cylinder pressure than diesel fuel because of the long ignition delay and lower calorific value of the former [60,61]. These figures indicate that diesel exhibited a maximum cylinder peak pressure of 55.118 bar at 13.875° after top dead center (ATDC), whereas the minimum cylinder peak pressure was 54.876 bar at 13.875° ATDC with the PB20 blend. Fig. 11 shows that CIB10 and CIB20 obtained a higher peak cylinder pressure of 55.193 bar (14.01° ATDC) and 55.222 bar (14.125° ATDC), respectively, than that of diesel fuel. Fig. 10 illustrates that the peak cylinder pressure of JB10 and JB20 were 54.913 bar and 54.893 bar, respectively, and both occurred at 13.875° ATDC. Furthermore, C. inophyllum biodiesel blends showed higher peak cylinder pressure than diesel, palm, and jatropha biodiesel blends because of their high cetane number. The properties of biodiesel, such as high cetane number, high viscosity, and low volatility, are the main factors for the differences in peak cylinder pressure among the biodiesel blends [62]. Therefore, PB20 showed lower peak cylinder pressure than diesel, PB10, JB10, JB20, CIB10, and CIB20. The low calorific value of PB20 is the main reason for this result. A total of 20% of the biodiesel blends could be decreased the peak cylinder pressure as a result of the comparatively lower calorific value of the biodiesel blend than diesel fuel. High biodiesel concentrations in the blend could increase the peak cylinder pressure in the combustion process [63]. From the heat release rate plot, a negative heat release at the primary stage of combustion can be observed because of vaporization of the fuel that accumulated during the ignition delay; when combustion is initiated, the heat release rate rapidly becomes positive [8]. From the heat release rate analysis, the peak heat release rate was determined at 36.035 J/°CA with diesel fuel. Fig. 11 shows

55 50

65

Diesel PB10 PB20

55 45 35

45 25 40

15

35

5

25 30 -10

20 1000

1200

1400

1600

1800

2000

2200

2400

Heat Release Rate (J/°CA)

Diesel 450

-5 -5

0

5

10

15

20

25

30

Crank Angle °CA

Engine speed (rpm) Fig. 8. Smoke opacity of diesel and biodiesel blends with variations of engine speed.

Fig. 9. Variations in the combustion pressure and heat release rate of diesel and palm biodiesel blends at engine speed of 1600 rpm.

Please cite this article in press as: Monirul IM et al. Assessment of performance, emission and combustion characteristics of palm, jatropha and Calophyllum inophyllum biodiesel blends. Fuel (2016), http://dx.doi.org/10.1016/j.fuel.2016.05.010

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I.M. Monirul et al. / Fuel xxx (2016) xxx–xxx

TDC

65

Diesel JB10 JB20

55 50

55 45 35

45 25 40

15

35

5

30

-5 -10

-5

0

5

10

15

20

25

Heat Release Rate (J/°CA)

Combustion Pressure (bar)

60

30

Crank Angle °CA Fig. 10. Variations in the combustion pressure and heat release rate of diesel and jatropha biodiesel blends at engine speed of 1600 rpm.

TDC

65

Diesel CIB10 CIB20

55 50

55 45 35

45 25 40

15

35

5

30

Heat Release Rate (J/°CA)

Combustion Pressure (bar)

60

-5 -10

-5

0

5

10

15

20

25

30

Crank Angle °CA Fig. 11. Variations in the combustion pressure and heat release rate of diesel and Calophyllum inophyllum biodiesel blends at engine speed of 1600 rpm.

that CIB10 exhibited a higher peak heat release rate (36.279 J/°CA) than those of diesel and other biodiesel blends. Fig. 9 shows that the PB10 and PB20 fuels displayed peak heat release rates of 35.962 J/°CA and 35.697 J/°CA, respectively; these rates are approximately 1.20% and 1.95% lower, respectively, than the that of the baseline diesel fuel. Moreover, the recorded peak heat release rates were determined at 36.088 J/°CA and 35.561 J/°CA with JB10 and JB20, respectively (Fig. 10). The highest reduction in the peak heat release rate for JB20 was determined to be 1.33%, 1.12%, 0.38%, 1.48%, 2.02%, and 1.71% lower than diesel, PB10, PB20, JB10, CIB10, and CIB20, respectively. These results can be attributed to the lower calorific value of the biodiesel blends than that of the baseline diesel fuel. The high viscosity of the biodiesel blend is another reason for these results. Therefore, this condition may cause slow vaporization of the biodiesel blend, thereby contributing to less premixed combustion. Another observation is that from

the peak heat release rate during the premixed combustion phase for the biodiesel blends, the recorded peak was consistently lower than that of the baseline diesel fuel except for the CIB blends. This result clearly indicates that 20% of the biodiesel blends can reduce the peak in the heat release rate during the premixed combustion phase. 4. Conclusion This study investigated the engine performance, emission, friction, and wear characteristics of palm and C. inophyllum biodiesel blends. The following conclusions can be drawn based on the experimental results.
Average BSFC was increased by 7.96–10.15% while operating on 10% and 20%, blends of PB, JB and CIB. Average brake power for PB20 and JB20 were 9.31% and 12.93% lower than that of diesel fuel. CIB10 showed higher BTE than diesel and other biodiesel blends did.
Average CO and HC emissions of palm biodiesel blends were reduced more than diesel and C. inophyllum biodiesel blends were, except for CIB10. PB20 produced 13.85% lower CO emissions than diesel fuel did. Average HC emission of PB20 and JB20 were 9% and 10.81% lower than that of diesel fuel. The average smoke opacity of CIB blends was lower than that of diesel and PB blends.
Average NOX emissions of diesel were lower than those of biodiesel blends. The maximum amount of NOX emissions was found from CIB20 at approximately 337.2 ppm at 2400 rpm engine speed. PB10 and PB20 produced lower amounts of NOX emissions than other biodiesel blends.
The peak cylinder pressure and peak heat release rate of CIB20 were higher than those of diesel fuel, palm, and jatropha biodiesel blends in the premixed combustion zone. Each fuel type exhibited a similar behavior for the mixing controlled phase. In conclusion, these observations and results suggest that PB20 displays the most favorable engine performance; it also has lower emissions in terms combustion analysis. Therefore, this blend can be used in automobile engines without aid of any engine modification. Acknowledgements The authors would like to thanks University of Malaya, Malaysia for financial assistance by means of High Impact Research grant project: ‘‘Clean Diesel Technology for Military and Civilian Transport Vehicles” of grant numbers UM.C/HIR/MOHE/ENG/07 and FP 051-2014B.

Appendix A A.1. Uncertainty analysis of BSFC at engine speed 2400 rpm Fuel

Diesel PB10 PB20 JB10 JB20 CIB10 CIB20

Test 1

0.451 0.455 0.478 0.459 0.506 0.398 0.433

Test 2

0.443 0.462 0.472 0.462 0.514 0.402 0.438

Test 3

0.447 0.457 0.469 0.465 0.51 0.394 0.434

Max.

0.451 0.462 0.478 0.465 0.514 0.402 0.438

Min.

0.443 0.455 0.469 0.459 0.506 0.394 0.433

Accuracy

Avg.

Uncertainty (%)

+0.05

0.05

+



0.501 0.512 0.528 0.515 0.564 0.452 0.488

0.393 0.447 0.405 0.4585 0.419 0.4735 0.409 0.462 0.456 0.51 0.344 0.398 0.383 0.4355 Uncertainty level

0.894855 0.763359 0.95037 0.649351 0.784314 1.005025 0.574053 0.803046

0.894855 0.763359 0.95037 0.649351 0.784314 1.005025 0.574053 0.803046

Please cite this article in press as: Monirul IM et al. Assessment of performance, emission and combustion characteristics of palm, jatropha and Calophyllum inophyllum biodiesel blends. Fuel (2016), http://dx.doi.org/10.1016/j.fuel.2016.05.010

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I.M. Monirul et al. / Fuel xxx (2016) xxx–xxx

A.2. Uncertainty analysis of BP at engine speed 2400 rpm Fuel

Test 1

Test 2

Test 3

Max.

Min.

Accuracy

Avg.

+0.02

0.02

Diesel PB10 PB20 JB10 JB20 CIB10 CIB20

4.48 4.41 4.18 4.15 3.98 4.16 4.06

4.57 4.32 4.21 4.1 4.04 4.21 4.11

4.51 4.35 4.24 4.08 4.01 4.14 4.07

4.57 4.41 4.24 4.15 4.04 4.21 4.11

4.48 4.32 4.18 4.08 3.98 4.14 4.06

4.59 4.43 4.26 4.17 4.06 4.23 4.13

4.46 4.3 4.16 4.06 3.96 4.12 4.04 Uncertainty level

Uncertainty (%) +



4.525 4.365 4.21 4.115 4.01 4.175 4.085

0.994475 1.030928 0.712589 0.850547 0.74813 0.838323 0.611995 0.826712

0.994475 1.030928 0.712589 0.850547 0.74813 0.838323 0.611995 0.826712

Avg.

Uncertainty (%)

A.3. Uncertainty analysis of CO emission at engine speed 2400 rpm Fuel

Diesel PB10 PB20 JB10 JB20 CIB10 CIB20

Test 1

0.455 0.436 0.434 0.459 0.428 0.482 0.477

Test 2

0.468 0.446 0.421 0.448 0.441 0.471 0.488

Test 3

0.475 0.441 0.432 0.455 0.43 0.466 0.481

Max.

0.475 0.446 0.434 0.459 0.441 0.482 0.488

Min.

0.455 0.436 0.421 0.448 0.428 0.466 0.477

Accuracy +0.01

0.01

0.485 0.456 0.444 0.469 0.451 0.492 0.498

0.445 0.426 0.411 0.438 0.418 0.456 0.467 Uncertainty level

+



0.465 0.441 0.4275 0.4535 0.4345 0.474 0.4825

2.150538 1.133787 1.520468 1.212789 1.495972 1.687764 1.139896 1.477316

2.150538 1.133787 1.520468 1.212789 1.495972 1.687764 1.139896 1.477316

Avg.

Uncertainty (%)

A.4. Uncertainty analysis of HC emission at engine speed 2400 rpm Fuel

Diesel PB10 PB20 JB10 JB20 CIB10 CIB20

Test 1

24.4 20.7 21.4 22 19.9 21.9 23.8

Test 2

25.4 21.4 20.4 21.8 20.8 21.6 23.2

Test 3

24.6 21.8 20.6 22.5 20.5 20.7 24.1

Max.

25.4 21.8 21.4 22.5 20.8 21.9 24.1

Min.

24.4 20.7 20.4 21.8 19.9 20.7 23.2

Accuracy +1

1

26.4 22.8 22.4 23.5 21.8 22.9 25.1

23.4 19.7 19.4 20.8 18.9 19.7 22.2 Uncertainty level

+



24.9 21.25 20.9 22.15 20.35 21.3 23.65

2.008032 2.588235 2.392344 1.580135 2.211302 2.816901 1.902748 2.214243

2.008032 2.588235 2.392344 1.580135 2.211302 2.816901 1.902748 2.214243

Avg.

Uncertainty (%) +



385.5 398.5 403.5 390 396.5 408 419

0.648508 0.878294 0.619579 0.512821 0.630517 0.490196 0.954654 0.676367

0.648508 0.878294 0.619579 0.512821 0.630517 0.490196 0.954654 0.676367

A.5. Uncertainty analysis of NOX emission at engine speed 2400 rpm Fuel

Test 1

Test 2

Test 3

Max.

Min.

Accuracy +1

1

Diesel PB10 PB20 JB10 JB20 CIB10 CIB20

383 395 406 388 399 406 416

388 402 401 392 394 410 423

387 397 405 390 395 408 415

388 402 406 392 399 410 423

383 395 401 388 394 406 415

389 403 407 393 400 411 424

382 394 400 387 393 405 414 Uncertainty level

Please cite this article in press as: Monirul IM et al. Assessment of performance, emission and combustion characteristics of palm, jatropha and Calophyllum inophyllum biodiesel blends. Fuel (2016), http://dx.doi.org/10.1016/j.fuel.2016.05.010

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Please cite this article in press as: Monirul IM et al. Assessment of performance, emission and combustion characteristics of palm, jatropha and Calophyllum inophyllum biodiesel blends. Fuel (2016), http://dx.doi.org/10.1016/j.fuel.2016.05.010