Exhaust emissions reduction from diesel engine using

0 downloads 8 Views 603KB Size Report
Jul 25, 2016 - Heat Mass Transfer ... methyl ester of Annona oil is blended with eucalypts oil in 10, 20, 30, 40 and 50 %. .... nearly 60 % methyl oleate. .... to higher heat release in the starting of combustion which increases the exhaust gas ...

Heat Mass Transfer DOI 10.1007/s00231-016-1882-6

ORIGINAL

Exhaust emissions reduction from diesel engine using combined Annona–Eucalyptus oil blends and antioxidant additive R. Senthil1 · R. Silambarasan1 · G. Pranesh1 

Received: 6 November 2015 / Accepted: 25 July 2016 © Springer-Verlag Berlin Heidelberg 2016

Abstract The limited resources, rising petroleum prices and depletion of fossil fuel have now become a matter of great concern. Hence, there is an urgent need for researchers to find some alternate fuels which are capable of substituting partly or wholly the higher demanded conventional diesel fuel. Lot of research work has been conducted on diesel engine using biodiesel and its blends with diesel as an alternate fuel. Very few works have been done with combination of biodiesel–Eucalypts oil without neat diesel and this leads to lots of scope in this area. The aim of the present study is to analyze the performance and emission characteristics of a single cylinder, direct injection, compression ignition engine using eucalyptus oil–biodiesel as fuel. The presence of eucalyptus oil in the blend reduces the viscosity and improves the volatility of the blends. The methyl ester of Annona oil is blended with eucalypts oil in 10, 20, 30, 40 and 50 %. The performance and emission characteristics are evaluated by operating the engine at different loads. The performance characteristics such as brake thermal efficiency, brake specific fuel consumption and exhaust gas temperature are evaluated. The emission constituents measured are Carbon monoxide (CO), unburned hydrocarbons (HC), Oxides of nitrogen (NOx) and Smoke. It is found that A50-Eu50 (50 Annona + 50 % Eucalyptus oil) blend showed better performance and reduction in exhaust emissions. But, it showed a very marginal increase in NOx emission when compared to that of diesel. Therefore, in order to reduce the NOx emission, antioxidant additive (A-tocopherol acetate) is mixed with

* R. Senthil [email protected] 1



Department of Mechanical Engineering, University College of Engineering Villupuram, Villupuram, Tamil Nadu, India

Annona–Eucalyptus oil blends in various proportions by which NOx emission is reduced. Hence, A50-Eu50 blend can be used as an alternate fuel for diesel engine without any modifications.

1 Introduction Annona squamosa is a family member of Custard apple trees which are known as Annonaceae. It is commonly found in India, Cultivated in Thailand and originates from the West Indies and South America [1]. Annona squamosa produces fruits that are usually called sugar apple or custard apple in English, sitafal in Marathi, sharifa in Hindi and sitaphalam in Tamil & Telugu in India and corossolier and cailleux, pommier cannelle in French [2]. It is mainly grown in gardens for its fruits and ornamental value. It is considered as beneficial for cardiac disease, diabetes, hyperthyroidism and cancer. The root is considered as a drastic purgative [3]. The experiments are carried out in a single cylinder four stroke DI diesel engine using Annona methyl ester (AME) and its blends with diesel. It was reported that AME at 20 % blend shows better performance and lower exhaust emissions. Further, it was found that CO, HC and smoke emission reduced considerably and NOx emission slightly increased for the various proportions of Annona methyl ester [4]. The experiment on the utilisation of eucalyptus oil and orange oil in small passenger cars was investigated. It was reported that eucalyptus oil obtained from leaves by means of steam extraction, contains 1.8-cineole (C10H18O) as the main ingredient. It was reported that while using 100 % of eucalyptus oil, there is a difficulty in the engine starting under the low atmospheric temperature because of the high flash point of eucalyptus oil. It was further reported that the

13



phase separation problem was not noticed when the eucalyptus oil was blended with ethanol and gasoline [5]. The performance, combustion and exhaust emissions characteristics of spark-ignition engines at two different compression ratios of 7.4 and 9.0 using eucalyptus oil and orange oil as alternative fuels were studied. Tests were conducted using 20 % volume of orange oil and eucalyptus oil that were blended separately with gasoline. The results indicated that the performance of the fuel blends was much better than that of gasoline fuel, in particular, at the higher compression ratio. Hydrocarbons and carbon monoxide emission levels in the engine exhaust were considerably reduced with fuel blends at both the compression ratios [6]. The experiment was conducted to study the performance, combustion and emission characteristics of a diesel engine using biodiesel-eucalyptus oil blends along with addition of 10 % diethyl ether. It is concluded that B20Eu70DEE10 showed better performance and reduction in exhaust emissions when compared to that of neat diesel [7]. The experimental study on four stroke DI, Ricardo/ cussons using various bio diesels such as cotton seed oil, soyabean oil, sunflower oil, rapeseed oil, palm oil, corn oil and olive kernel oil and their corresponding methyl ester at the blends ratio of 10/90 and 20/80 showed better performance and reduction in exhaust emissions [8]. The effect of vegetable oils and their methyl esters such as (raw sun flower, raw cotton seed oil, raw soybean oil and their methyl esters, refined corn oil, distilled opium poppy oil and refined rapeseed) showed increase of smoke emission and NO2 emission were less [9]. The biodiesel was produced from Mahua (Madhuca indica) oil through esterification followed by transesterification. The kinetic viscosity and cetane value were higher for mahua oil and thus, will be favorable for combustion. The increase in brake thermal efficiency and decrease in specific fuel consumption was observed in the case of esterified mahua oil (at 75 % mahua oil blends) compared to that of diesel fuel. The effect of mahua oil methyl ester, ethyl and butyl esters of a four stroke, direct injection, constant speed, compression ignition diesel engine, on performance and emissions were analyzed. The CO, HC and NOx emission is low for alkali esters as compared to neat diesel fuel. The ethyl ester showed lower NOx emission compared to other esters [10–14]. The effect of antioxidant L-ascorbic acid on engine performance and emissions of a diesel engine fuelled with methyl ester of Annona oil (MEAO). They have found that the antioxidant additive mixture (MEAO + LA200) is effective in the control of nitrogen oxides (NOx) and hydrocarbon (HC) emission of MEAO fuelled engine without doing any engine modification. They have concluded that

13

Heat Mass Transfer

by using MEAO, the NOx emission is reduced effectively as compared to neat diesel fuel [15]. The use of p-phenylenediamine derived aromatic amine antioxidants for NOx reduction in a soybean biodiesel fuelled DI diesel engine was studied. The antioxidant additives were tested on computerised Kirloskar-make four stroke water cooled single cylinder diesel engine of 4.4 kW rated power. They have found that significant reduction of NOx could be achieved by the addition of antioxidants but smoke, CO and HC emissions were found to have increased [16]. It is reported that the antioxidant additive is effective in controlling NOx emission of methyl ester fuelled diesel engine. But, other emission such as HC, CO and Smoke and BTE, BSFC were found [17]. The neat biodiesel using in the engine the following problems are occur, carbon deposits, injector coking, and reduce engine performance. And then cost of Annona oil biodiesel and Eucalyptus oil in Indian rupees 28 and 26 respectively. The present work aims at investigating the performance and emission characteristics of eucalyptus oil blends and to find its suitability as fuel for CI engine. Further, the NOx emission is reduced by using antioxidant additive (A-tocopherol acetate) with A50-Eu50 blend.

2 Materials and methods 2.1 Materials 2.1.1 Annona biodiesel Annona squamosal seeds were sun dried for a week to the required dry weight and moisture content and then, the hard nuts of the seeds were removed by physically hitting with a hard metal and the kernel was obtained. The seeds for this study were collected from ripened fruit, and grinded using home-blender without a prior drying process. The Air–Fuel ratio for diesel and biodiesel, during the test is 15:1 and 13.8:1 respectively. A10–Eu90 Annona oil 10 %–Eucalyptus oil 90 % A20–Eu80 Annona oil 20 %–Eucalyptus oil 80 % A30–Eu70 Annona oil 30 %–Eucalyptus oil 70 % A40–Eu60 Annona oil 40 %–Eucalyptus oil 60 % A50–Eu50 Annona oil 50 %–Eucalyptus oil 50 %

2.1.2 Eucalyptus oil Eucalyptus oil comes under the category of essential oil. Essential oil is defined as volatile oil which can be extracted

Heat Mass Transfer

from plant leaves by steam distillation. Eucalyptus trees are grown extensively due to their potential use in paper and construction industries. Eucalyptus oil can be extracted from eucalyptus leaves by means of steam distillation. The empirical formula for cineole is C10H18O and its systematic name is 1, 3, 3-trimethyl-2-oxabicyclo octane [7]. 2.1.3 Gas chromatography (GC) The methyl esters of Eucalyptus Oil were tested for their fatty acid contents in a gas chromatography (GC) test for the purpose of finding out the predominant fatty acid components. From the GC test, it was found that Eucalyptus Oil contains 35 % saturated acids (palmitic and stearic) and 64 % unsaturated acids (linoleic and oleic). The major constituent of Eucalyptus Oil is oleic acid that differentiates Eucalyptus Oil from other vegetable oils. The methyl ester of Eucalyptus Oil used in the present investigation contains nearly 60 % methyl oleate. 2.2 Transesterification Transesterification is an effective way to reduce the viscosity of the vegetable oil. During the process, triglyceride of vegetable oil read with alcohol in the presence of catalyst such as NaOH and form glycerol and vegetable oil methyl ester.

3 Properties and characteristics of Annona methyl ester The properties of fuel were tested according to United States standard method (ASTM). Table 1 shows the properties of diesel, Annona methyl ester and eucalyptus oil. From

Table 1  Specifications of the experimental engine Manufacturer

Kirloskar oil engines limited

Model Type of engine

Displacement Max brake power Speed Compression ratio Lubrication system Bore and stroke Method of cooling Flywheel diameter

SV1 Vertical, 4-stroke cycle, single acting, single cylinder, high speed compression ignition diesel engine 661 cc 3.5 kW 1500 rpm 17.5:1 Forced feed system 87.5 × 110 (mm) Water cooled 1262 mm

Injection pressure

200 bar

Table 2  Specifications of the exhaust gas analyzer Manufacturer

SMS autoline equipments private limited

Type Model Power requirements Operating pressure Operating temperature Storage temperature Ranges  CO  CO2  HC  O2  NOX Resolution  CO  CO2  HC  O2  NOX Principle  CO  CO2  HC  O2

Crypton 290 five gas analyser EN2 230 V AC, 50–60 Hz 750–1100 m bar +5 to +40 °C −20 to +55 °C

 NOX

0–10 % 0–20 % 0–10,000 PPM 0–25 % 0–5000 PPM 0.01 % 0.10 % 1 PPM 0.01 % 1 PPM NDIR NDIR NDIR Electrochemical Electrochemical

Table 1 it is observed that the eucalyptus oil has lower viscosity flash point, cetane number and higher heating value that of AME. Table 2 shows the properties of blended fuel.

4 Experimental setup and testing procedure Figure  1 shows the schematic diagram of the test engine. The test engine is a single cylinder, water cooled, DI diesel engine. The specification of the test engine is shown in Table 3. The test engine is directly coupled with an electric dynamometer. Exhaust gas analyzer is used to measure the exhaust emission such as HC, CO and NOx emission. The accuracy of gas analyzer is shown in Table 4. The smoke meter is used to measure the smoke emission. The specification of smoke meter is shown in Table 5. Lab view base engine performance software is used for performance calculation. The engine was started and warmed up long enough to check any oil leakage. The engine runs for about 10 min to attain stable conditions. Experiments were conducted at different load levels from 0 to 15 kg sequentially in steps of 3 kg. The readings are taken in ambient condition. The experiments are repeated for three turns and average values

13



Heat Mass Transfer

Fig. 1  Schematic Diagram of the Engine set up

5 Results and discussion

Table 3  Specifications of the smoke meter Type

AVL 437 smoke meter

Make Measuring range Smoke temperature Ambient temperature Humidity Power supply

AVL india private limited 0–100 HSU (hatridge smoke units) 250 °C (maximum at entrance) 0–50 °C 90 % at 50 °C (non conditioning) 205 A, 11.5–36 V DC

Principle

Light absorption principle

Table 4  Properties of test fuels Properties

Diesel

Eucalyptus oil Annona biodiesel

Density  °C (g/m3) Heating value (kJ/kg) Kinematic viscosity (Cst)

0.84 0.90 42,700 43,270 2.9 2.0

0.872 41,000 5.18

Flash point  °C

54

58

76

Cetane number

49

18

52

are taken and to enhance the accuracy of the results. At the end of the experiment, the fuel was switched back to the diesel and the engine was kept running for a while before shutdown to remove the test fuel from fuel tank line and injection system. The uncertainties are shown in Table 6.

13

5.1 Performance characteristics 5.1.1 Brake specific fuel consumption (BSFC) The variation of brake specific fuel consumption for different Annona–Eucalypts oil blends and neat diesel at various brake power is shown in Fig. 2. Among different blends A50-Eu50 showed lower BSFC than that of different blends and neat diesel. This is due to the A50-Eu50 having higher calorific value and lower density leads to proper atomization which results in lower BSFC. 5.1.2 Brake thermal efficiency (BTE) The variation of brake thermal efficiency for different Annona–Eucalypts oil blends and neat diesel at various brake power is shown in Fig. 3. Among different blends, A50-Eu50 showed slightly higher brake thermal efficiency than that of other blends and neat diesel. The reason for increasing brake thermal efficiency is the presence of higher percentage of eucalypts oil in the Annona methyl ester blends. The mixing of eucalyptus oil in biodiesel yields good brake thermal efficiency. Initially the thermal efficiency of the engine is improved by increasing concentration of the eucalyptus oil in the molecules contain some amount of oxygen, which takes part in the combustion

Heat Mass Transfer Table 5  Properties of fuel blends

Properties

A10-Eu90

A20-Eu80

A30-Eu70

A40-Eu60

A50-Eu50

Density  °C (g/m ) Heating value (kJ/kg) Kinematic viscosity (Cst) Flash point  °C

0.8972 43,043 2.318 59.8

0.8944 42,816 2.636 61.6

0.8916 42,584 2.954 63.4

0.8888 42,362 3.272 65.2

0.886 42,135 3.59 67

Cetane number

21.4

24.8

28.2

31.6

35

3

Table 6  Experiment uncertainties

35

Parameters

Systematic errors (±)

30

Speed Load Time Brake power Temperature Pressure

1 ± rpm ±0.1 N ±0.1 s ±0.15 kW +0.15 to −0.15 +0.1 to −0.1 +0.2 to −0.2 +0.2 to −0.2 +0.15 to −0.15 +0.2 to −0.2

NOx CO CO2 HC Smoke

BTE (%)

25 20

Diesel A50Eu50 A40Eu60 A30Eu70 A20Eu80 A10Eu90

15 10 5 0

0

1

2

3

4

BP (kW)

Fig. 3  Variation of brake thermal efficiency versus brake power

±1 HSU

250

Diesel A50Eu50 A40Eu60 A30Eu70 A20Eu80 A10Eu90

BSFC (Kg/kW-hr)

0.8 0.7 0.6

200

EGT (°C)

0.9

0.5

150

Diesel A50Eu50 A40Eu60 A30Eu70 A20Eu80 A10Eu90

100

0.4 50

0.3 0.2

0

0.1 0

0

1

2

3

4

BP (kW)

0

1

2

3

4

BP (kW)

Fig. 4  Variation of exhaust gas temperature versus brake power

Fig. 2  Variation of Brake specific consumption versus brake power

process and also better vaporisation and mixture preparation of fuel resulting in rapid heat release rate. 5.1.3 Exhaust gas temperature (EGT) The variation of exhaust gas temperature for different Annona–Eucalypts oil blends and neat diesel at various brake power is shown in Fig. 4. Among different blends A50-Eu50 showed higher EGT than that of different blends and neat diesel. The reason of increase in exhaust gas temperature with the increase in the proportion of eucalypts oil content in the Annona blend reduces the cetane number of

the blend because of the lower cetane number of the eucalypts oil. This higher cetane number decreases the ignition delay and accumulated Air–Fuel mixture which leads to higher heat release in the starting of combustion which increases the exhaust gas temperature. 5.2 Emission characteristics 5.2.1 Carbon monoxide emission (CO) The variation of carbon monoxide emission for different Annona–Eucalypts oil blends and neat diesel at various brake power is shown in Fig. 5. Among different blends

13



Heat Mass Transfer 0.25

A50Eu50

A40Eu60

A30Eu70

A20Eu80

A10Eu90

70

Diesel

A50Eu50

60

A40Eu60

A30Eu70

A20Eu80

A10Eu90

3

4

50

0.15

HC (ppm)

CO (%)

0.2

Diesel

0.1

40 30 20 10

0.05

0

0

0

1

2

3

0

1

4

BP (kW)

2

BP (kW)

Fig. 6  Variation of hydrocarbon emission versus brake power

Fig. 5  Variation of carbon monoxide emission versus brake power 900

Diesel A40Eu60 A20Eu80

700

NOx (ppm)

A50-Eu50 showed lower CO emission when compared to that of other blends and neat diesel. This is mainly due to the oxygen content present in both the biofuels. Further, this is due to higher oxygen in the fuel rich zones which leads to complete combustion which in turn reduces the CO emission.

800

A50Eu50 A30Eu70 A10Eu90

600 500 400 300 200

5.2.2 Hydrocarbon emission (HC)

100 0

The variation of hydrocarbon for different Annona–Eucalypts oil blends and neat diesel at various brake power is shown in Fig. 6. Among different blends A50-Eu50 showed lower HC emission when compared to that of other blends and neat diesel. The reason for decrease in HC emission is lower distillation temperature of eucalyptus oil which leads to poor volatility characteristics of methyl ester of Annona. It improves the evaporation rates and better mixture rate and leads to improved combustion. It contributes to reduction in HC emission. 5.2.3 Oxides of nitrogen emission (NOx) The variation of Oxides of Nitrogen Emission for different Annona–Eucalypts oil blends and neat diesel at various brake power is shown in Fig. 7. It can be observed from the figure that NOx emission increasing with increase in proportion of eucalypts oil in the blends. This is due to presence of oxygen present in the both fuels and leads to complete combustion. This complete combustion normally will create high combustion temperature and leads to increase in NOx emission. The reason for increase in NOx emission is the lower cetane number with higher proportions of eucalypts oil. This lower cetane number increases the ignition delay and accumulated air fuel mixture which leads to high temperature.

13

0

1

2

3

4

BP (kW)

Fig. 7  Variation of oxides of nitrogen emission versus brake power

5.2.4 Smoke The variation of smoke emission for different Annona– Eucalypts oil blends and neat diesel at various brake power is shown in Fig. 8. It is found that smoke emission for biodiesel blends are lower than that of diesel. Among different blends A50-Eu50 showed lower smoke emission when compared to that of other blends and neat diesel. This is due to complete combustion caused by the oxygenated blends. This is also due to an improvement in diffusion combustion and also attributed to a reduced droplet size of the spray and better evaporation of the blended fuel compared to diesel. 5.3 Reduction of NOx emission using antioxidant additive From the experimental investigation, it has been concluded that, A50-Eu50 shows better performance and reduction in emissions such as HC, CO and smoke but there is an increase of NOx emission. However, the properties of 50 %

Heat Mass Transfer

additive. Further, A-tocopherol acetate is a chain breaking antioxidant additive because of its ability to decrease it phenelic hydrogen to free radicals. Hence the NOx emission is reduced with the additive of A-tocopherol acetate [16].

45 40

SMOKE (HSU)

35 30 25 20

Diesel A50Eu50 A40Eu60 A30Eu70 A20Eu80 A10Eu90

15 10 5 0

0

1

2

3

4

BP (kW)

6 Conclusion In the present work, the performance, emission and combustion characteristics on a four stroke, diesel engine using Annona Methyl Ester-eucalyptus oil blends have been investigated, discussed and compared with diesel fuel. From the experimental investigation, the following conclusion were are drawn:

Fig. 8  Variation of smoke emission versus brake power

eucalyptus oil are presented in this work because of its less viscous and higher cetane number value while using higher values blends. Since A50-Eu50 was chosen as optimum blend because of its better performance and exhaust emissions except its NOx emission. Further, the NOx emission is reduced by using antioxidant additive. The antioxidant additive (A-tocopherol acetate) is accurately weighted using electronic weighing machine and added to A50-Eu50 blend. The antioxidant is mixed with A50-Eu50 blend at various concentrations such as 100 mg (A50-Eu50  + AT100), 200 mg (A50-Eu50 + AT200), 300 mg (A50-Eu50 + AT300), and 400 mg (A50-Eu50 + AT400). The specification of the antioxidant additive (A-tocopherol acetate) is shown in Table 7. 5.3.1 Comparison of NOx emission

1. It is concluded that the brake thermal efficiency of A50-Eu50 is higher than to that of diesel. So the diesel engine can perform satisfactorily on Annona Methyl Ester-eucalyptus oil biodiesel and its blends without any engine modifications. 2. It is found that CO, HC and smoke emissions are less for A50-Eu50 compared to that of diesel. 3. The NOx emission A50-Eu50 was slightly higher than that of diesel which can be reduced by using antioxidant additive. The maximum reduction of NOx emission is 21 % for A50-Eu50 blend. Hence it is concluded that A50-Eu50 was selected as the best optimum blend because of its improvement in performance and reduction of exhaust emissions without doing any major modification in existing diesel engine.

References

Figure  7 shows the variation of NOx emission for diesel, A50-Eu50, (A50-Eu50 + AT100), (A50-Eu50 + AT200), (A50-Eu50  + AT300), (A50-Eu50 + AT400) at various brake power. Among the different blends NOx emission for A50-Eu50 + AT100 is decreased by 21 % when compared to that of A50-Eu50 blend. This is due to the reduction in the formation of the free radicals from antioxidant Table 7  Specification of antioxidant additive (A-tocopherol acetate) Specification CAS number Minimum assay Molecular weight Acid value Free tocopherol

7695-91-2 96–102 % 472.75 2 2 %

Sulphated ash

0.1 %

1. Parvin MS, Islam ME, Rahman MM, Haque ME (2003) Toxicological evalution of Annotemoyin-1 isolated from Annona squamosa Linn. on Long Evan’s Rats. Pak J Biol Sci 6:1593–1596 2. Shardul K, Swati J, Prajakta K, Prafullachandra T, Santosh P, Arun R (2013) Proximate analysis of peel and seed of Annona squamosa (custard apple) fruit. Res J Chem Sci 3(2):92–94 3. Shirwaikar A, Rajendran K, Kumar CD, Bodla R (2004) In vitro antioxidant studies of Annonasquamosa Linn. leaves. Indian J Exp Biol 42:803–807 4. Senthil R, Silambarasan R (2015) Annona: a new biodiesel for diesel engine: a comparative experimental investigation. J Energy Inst 88(4):459–469 5. Takeda S (1984) Utilisation of Eucalyptus oil and orange oil for small passenger cars. SAE Technical paper no. 841332. doi:10.4271/841332 6. Poola RB, Nagalingam B, Gopalakrishnan KV (1994) Performance studies with biomass-derived high-octane fuel additives in a two stroke spark-ignition engine. Biomass Bioenergy 6:369–379 7. Senthil R, Sivakumar E, Silambarasan R (2015) Effect of die ethyl ether on the performance and emission characteristics of

13

a diesel engine using biodiesel–eucalyptus oil blends. RSC Adv 5:54019–54027 8. Rakopoulos CD, Antonopoulos KA, Rakopoulos DC (2006) Comparative performance and emission study of a direct injection diesel engine using blends of diesel fuel with vegetable oil or bio-diesel of various origins. Energy Conserv Manag 47:3272–3287 9. Altin R, Cetinkaya S, Yucesu HS (2001) The potential of using vegetable oil fuel as fuel for diesel engines. Energy Conserv Manag 42(5):529–538 10. Padhi SK, Singh RK (2010) Optimization of esterification and trans-esterification of mahua (madhucaindica) oil for production of bio-diesel. J Chem Pharm Res 2(5):599–608 11. Nandi S (2013) Performance of C.I engine by using Bio-diesel– Mahua oil. Am J Eng Res 2(10):22–47 12. Puhan S, Vedaraman N, Rambrahamam BV, Nagarajan G (2005) Mahua (Madhuca indica) seed oil: a source of renewable energy in India. J Sci Ind Res 64:890–896

13

Heat Mass Transfer 13. Puhan S, Vedaraman N, Ram BVB, Sankaranarayanan G, Jeychandran K (2005) Mahua oil (Madhuca indica seed oil) metyl ester as bio-diesel-preparation and emission characteristics. Biomass Bioenergy 28(1):87–93 14. Saravanan N, Nagarajan G, Puhan S (2010) Expermental investigation on a DI diesel engine fuelled with Madhuca indica ester and diesel blend. Biomass Bioenergy 34:838–843 15. Senthil R, Silambarasan R (2015) Environmental effect of antioxidant additives on exhaust emission reduction in compression ignition engine fuelled with Annona methyl ester. Environ Technol 36(16):2079–2085 16. Varatharajan K, Cheralathan M (2013) Effect of aromatic amine antioxidants on NOx emissions from a soybean biodiesel powered DI diesel engine. Fuel Process Technol 106:526–532 17. Balaji G, Cheralathan M (2015) Experimental investigation of antioxidant effect on oxidations stability and emissions in a methyl ester if neem oil fuel DI diesel engine. Renew Energy 74:910–916

Suggest Documents