An assessment on injection pressure and timing to reduce emissions on diesel engine powered by renewable fuel

Journal Pre-proof An assessment on injection pressure and timing to reduce emissions on diesel engine powered by novel biodiesel S.V. Karthic, M. Senthil Kumar, G. Nataraj, S. Vinoth Kumar, P. Pradeep, R. Pradeep PII:

S0959-6526(20)30233-X

DOI:

https://doi.org/10.1016/j.jclepro.2020.120186

Reference:

JCLP 120186

To appear in:

Journal of Cleaner Production

Received Date: 27 March 2019 Revised Date:

15 November 2019

Accepted Date: 17 January 2020

Please cite this article as: Karthic SV, Senthil Kumar M, Nataraj G, Vinoth Kumar S, Pradeep P, Pradeep R, An assessment on injection pressure and timing to reduce emissions on diesel engine powered by novel biodiesel, Journal of Cleaner Production (2020), doi: https://doi.org/10.1016/j.jclepro.2020.120186. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Ltd.

CRediT author statement: KARTHIC SV: Conceptualization, Methodology, Investigation, Writing - Original Draft, Writing - Review & Editing. M SENTHIL KUMAR: Supervision, Project administration, Funding acquisition. G NATARAJ: Software, Investigation. S VINOTH KUMAR: Validation, Resources, Investigation. P PRADEEP: Visualization, Investigation. R PRADEEP: Investigation.

An Assessment on Injection Pressure and Timing to reduce emissions on Diesel Engine Powered by novel Biodiesel

S.V.Karthic1*, M. Senthil Kumar1, G.Nataraj2, S.Vinoth Kumar1, P.Pradeep1, and R.Pradeep1 1

Department of Automobile Engineering, Anna University- Madras Ins*tute of Technology Campus, Tamil Nadu, India. 2

School of Mechanical Engineering, Vellore Ins*tute of Technology, Tamil Nadu, India. *

Email: [email protected]

ABSTRACT : Fuel injection pressure and fuel injection timing are significant injection parameters, which have a greater impact on engine performance, combustion, and emission. The main focus of this work is on improving the emissions and performance of the single cylinder diesel engine by changing the injection parameters with the engine being powered by novel Syzygium cumini oil biodiesel at various proportions (i.e., B30,70,100). In addition to that, the investigations were directed towards achieving the effective usage of biodiesel for the substitution of fast depleting diesel fuel. The experimental work was conducted on single cylinder, water-cooled, direct injection compression ignition engine at a constant speed of 1500 rpm with static fuel injection timing 23 degree before top dead centre and pressure of 200 bar. The engine tests were conducted at different fuel injection pressures (200, 220, o

240 and 260 bar) and different injection timings (21, 23 and 25 CA BTDC). Advancing the injection timing by 2 deg crank angle and increasing the fuel injection pressure to 240 bar resulted in superior performance. For instance, brake thermal efficiency of diesel and B30 increased by 17.85% and 16.66% respectively. While retarding fuel injection timing to 21-degree crank angle had an adverse effect on engine performance. B30 blend gave a superior performance compared with the other biodiesel blends. By advancing injection timing and increasing fuel injection pressure, hydrocarbon and carbon monoxide emissions for B30 blend were found to be 46.15% and 15.9% lesser than static fuel injection conditions. Maximum of 28.7% reduction in smoke emission was observed for advancing injection timing and increasing fuel injection pressure compared with the static injection conditions. But, nitric oxide emissions were relatively higher for advance injection timing and higher fuel injection pressure. The results led to the decision that advance injection timing and increasing fuel injection pressure could be chosen as better injection parameters for a diesel engine being powered by novel Syzygium cumini oil biodiesel with the massive reduction in emissions. Keywords: Pollution, Biodiesel, Injection timing, Injection pressure, Emissions, performance.

1

1. INTRODUCTION:

2

A tremendous development can be observed in Internal Combustion Engines on a daily basis.

3

Researchers are trying to find new and interesting innovations in internal combustion engines to

4

benefit the society at the cost of pollutant emissions. Diesel is the most widely used fuel in

5

automobiles, ship industries, generators and machineries due to its significant role in generating high

6

power compared to any other fuels. While there are daily advancements in automobile industry, on

7

the other hand, natural resources are affected by pollutants expelled from automobiles, industries,

8

power plants etc. Emission from compression ignition engines such as carbon-di-oxide, carbon

9

monoxide, oxides of nitrogen, unburnt hydrocarbon and smoke affect the atmosphere. These gaseous

10

emissions are very harmful to health and sometimes fatal too. The rate of depletion of fossil fuels is

11

increasing drastically. As per the report published by American Energy Information Administration

12

(EIA) and the International Energy Agency (IEA), the global energy consumption has increased up to

13

66.1% from 1980 until now i.e., 2% increase every year (Prediction of energy consumption, 2007).

14

Most of the researchers focus on finding new technologies for after-treatment process, in-cylinder

15

treatment, engine design modification, novel fuel research and alternative fuel resources. In the

16

current research work, alternative fuel resource and engine modification are the areas chosen to

17

reduce emissions and increase the performance of the engine.

18

In early 90’s, several researchers tested running compression ignition engines using

19

vegetable oils. But its preference was negligible due to its high viscosity and very low volatility.

20

Vegetable oils get deposited inside the cylinder and affects the combustion process whereas the gum

21

deposits on the piston ring, as a line, leads to hydrocarbon emission (Murugesan et al., 2009;

22

Dhinesh et al., 2016). Transesterification process is an effective way of converting free fatty acids

23

from vegetable oil into esters resulting in similar properties of diesel, which could be the solution for

24

the above-discussed problems (Chuah, L.F et al. 2017a). Biodiesel can be produced from esters of

25

vegetable oils, animal fats, non-edible seeds and waste cooking oils. When compared with diesel,

26

biodiesel has the least amount of Sulphur content and high oxygen content. Furthermore, biodiesel is

27

available in high quantities and eco-friendly in nature (Chuah, L.F et al., 2017b). There are certain

28

limitations in using biodiesel such as poor oxidation and cold starting. Mustard oil is one of the

29

accepted biodiesels that can be used to prolong the availability of the fossil fuel resources (Issariyakul

30

and Dalai 2014; Atabani 2013). Further, the biodiesel suffers from higher viscosity and higher density,

31

which might affect the combustion process. Several researchers believe that changing the injection

32

parameters could solve these problems. When the injection pressure and injection timing are altered,

33

it has a direct impact on combustion.

34

Suryawanshi and Deshpande 2005 powered an engine with Pongamia biodiesel and reported

35

a marginal improvement in brake thermal efficiency compared to diesel fuel under part load

36

conditions. They stated that the improvement in brake thermal efficiency was due to retarded injection

37

timing by 4 degree crank angle. Grimaldi et al., 2002 reported a minor improvement in engine

38

performance fuelled with biodiesel when compared with conventional diesel fuel, especially at full load

39

conditions. Oxygen-enriched fuels like biodiesel, biodiesel blended with ethanol or methanol improve

40

the brake thermal efficiency of the engine (Zhu et al., 2010).

1

1

Gumus et al., 2012 observed that the brake thermal efficiency got decreased for diesel-fuelled

2

operation when the fuel injection pressure was increased from 18 to 24 MPa. However, under

3

biodiesel operations, the brake thermal efficiency got improved with increasing fuel injection pressure

4

at full load conditions. The researchers noted 32.1% brake thermal efficiency for diesel (Fuel injection

5

pressure: 18 MPa) and 41.3% for biodiesel (Fuel injection pressure: 24 MPa). The study also

6

observed a common reduction in oxides of nitrogen emissions with increasing fuel injection pressure.

7

The emission of oxides of nitrogen can be reduced by retarding the injection timing without affecting

8

the performance of the engine (Agarwal et al., 2015). Suh HK et al inferred that, by advancing the

9

injection timing, one can experience the reduction in carbon monoxide emission for both biodiesel and

10

diesel fuel operations. Lee et al investigated the effects of blending ratios of biodiesel and inferred that

11

the carbon monoxide and hydrocarbon emissions got decreased with increasing biodiesel blend ratio.

12

But the oxides of nitrogen emissions got increased for higher biodiesel blend ratio in the presence of

13

oxygen content in biodiesel. Wang WG et al. noted that 35% of soybean biodiesel reduced the

14

hydrocarbon emissions when compared to conventional diesel fuel. Kuti OA et al. observed that the

15

ignition delay period got shortened with increasing fuel injection pressure and further got shortened

16

for biodiesel due to its higher cetane index. When the injection timing is advanced, then it results in

17

the accumulation of a large quantity of fuel during ignition delay period. The combustion takes place

18

earlier with the occurrence of peak in-cylinder near top dead centre, which gets converted into

19

maximum power (Panneerselvam et al., 2015).

20

In USA and European Union, biodiesel is commercially produced from edible sources such as

21

soybean or rapeseed oil in which the production cost is twice than that of the diesel. Since India is

22

deficient in edible oils, the national policy on biofuels encourages its production only from non-edible

23

oils (National policy of biofuels, India). Syzygium cumini is one of the traditional fruits found in India

24

with common names being black plum and java plum. Being an auspicious tree in Hindu religion, this

25

tree is often planted near temples (Morton JF. Naranjilla 2004). Syzygium cumini tastes sour due to its

26

gallic acid content (Venkateshwarlu.G 1952). It physically grows in the range of 10-30mm length and

27

each fruit contains a single non-edible seed. Due to its vast and steady availability throughout the

28

year, this can be considered as the best option for large-scale biodiesel production. In this work, non-

29

edible Syzygium cumini seeds were chosen for biodiesel production to meet the energy needs of

30

India. The tests were carried out in single cylinder diesel engine and the effects of novel Syzygium

31

cumini biodiesel blends are presented in this article. In addition to this, the effects of injection pressure

32

and timing are also briefly presented.

33 34

2. EXPERIMENTAL SET-UP AND PROCEDURE:

35

2.1 SYZYGIUM CUMINI OIL EXTRACTION PROCESS:

36

There are several methods of oil extraction processes available such as mechanical press

37

method, solvent extraction method, CO2 extraction, steam distillation, macretion, effleurage, cold

38

press extraction and water distillation process. Solvent extraction method was selected for this work

39

as it is cost-effective than other methods. Soxhlet extraction apparatus with of 500 mL flask capacity

2

1

and 300 mL extractor capacity was used in this method. The pictorial representation and original

2

apparatus are shown in the figure 1. Syzygium cumini seeds, weighing 400 grams, were placed

3

inside a thimble made up of thick filter paper. Extraction solvent was placed in the extractor flask. The

4

solvents like hexane, n-hexane, methanol and isopropanol were chosen to extract the oil. The solvent

5

was heated at a constant temperature of 65°C. The solvent vapour travelled through distillation arm

6

and got condensed once it reached the condenser. Then the condensed liquid droplets fall into the

7

thimble where the oil was extracted from the seeds. Solvent Soxhlet chamber and siphon tube got

8

filled simultaneously and when the oil reached the top of the siphon tube, it automatically got emptied

9

into the siphon tube and soxhlet chamber whereas the oil reached back to the extraction flask. This

10

process was repeated until the oil was completely extracted from the seeds. The time limit for the oil

11

extraction was limited based on the fatty acid content in Syzygium cumini seeds and the occurrence

12

of colour change in the extraction flask. All the solvents used in this process were subjected to colour

13

change in about 2.55 - 3.00 hours. After oil extraction, fractional distillation was executed to isolate the

14

oil from the solvent. Percentage of oil extraction can be calculated by using equation (1),

% =

weight of extracted oil × 100 − − − 1 weight of seeds

15

Percentages of oil yields from Syzygium cumini seeds with different solvents are shown in figure 2.

16

and the extracted Syzygium cumini oil is shown in figure 3.

17

2.2. FTIR analysis of SYZYGIUM CUMINI oil:

18

FTIR is used to find different types of functional groups and bonds that the molecule contains.

19

FTIR analysis was conducted on FT/IR-4700typeA with the resolution of 4cm-1, scanning speed of

20

2mm/s and filter with 30000Hz. FTIR spectra of SCO are shown in figure 4. From the spectra, at

21

wave number 2922.59 cm-1 and 2853.17 cm-1(O-H) stretch of COOH (carboxylic acid) is observed;

22

at 3008.41 cm-1: (C-H) stretch; at 1741.41 cm-1 : C=O stretch; At 1741.41 cm-1 presence of ester is

23

visualized. Single bond chemical structures C-C, C-N, C-O is visualized in fingerprint region between

24

wavenumber of 1461.78 cm-1 and 600 cm-1. Presence of carbon, hydrogen, oxygen atoms

25

invigorated the author to choose SCO for biodiesel production to balance the depletion of diesel fuel.

26

2.3 SYZYGIUM CUMINI BIODIESEL PREPARATION AND EXPERIMENTAL SETUP:

27

Viscosity is the primary challenge in substituting the pure seed oils for diesel fuels. Several

28

methods like mineralization, transesterification and pyrolysis reduce the viscosity. Among the above-

29

discussed methods, transesterification is one of the most efficient methods and was used in this work.

30

In transesterification (also called alcoholysis) process, triglyceride reacts with alcohol in the presence

31

of NaOH as the catalyst and produces fatty acid alkyl esters and glycerol as by-products. Initially, this

32

process was carried out with 300 mL of extracted raw Syzygium Cumini oil to find out the quantities of

33

catalyst required for Syzygium Cumini oil to produce huge amount of methyl esters. Figure 5 shows

34

the preparation of biodiesel. The properties like density, viscosity, calorific value and flash/fire point

35

for biodiesel and its blends were determined with respective measuring instruments at internal

36

combustion engines laboratory, Madras Institute of technology and the results are tabulated in table

3

1

1. This experimental work was conducted in a four-stroke single cylinder with water-cooled diesel

2

engine and its specifications are tabulated in table 2. The torque of the engine was measured using

3

Eddy current dynamometer. Figure 6 shows a schematic diagram of the experimental arrangement

4

whereas the figure 7 shows the test bench. Fuel was injected into the combustion chamber at

5

SFIT23D during the suction stroke. The inlet valve opened at 4.5° before TDC and closed at 35.5°

6

after BDC. The exhaust valve opened at 35.5° before BDC and closed at 4.5° after TDC. The

7

piezoelectric pressure sensor was mounted on the engine head which was amplified by a data

8

acquisition system. A crank angle encoder that had 0.1-degree resolution and was mounted in the

9

crankshaft obtained the crank angle position. Pressure crank-angle data and the heat-release rate

10

pattern were determined using an acquisition system called ‘AVL Indicom mobile 2012’ combustion

11

analyser. The emissions from the engine like NO, HC and CO were found using ‘AVL di gas 444’

12

analyser. The smoke was measured using an ‘AVL 437C’ smoke meter. RARU of the instruments

13

used in this experimental work is tabulated in table.3.

14

2.4 IMPACT OF CHANGE IN INJECTION PRESSURE AND INJECTION TIMING:

15

The biodiesel chosen for the study was more viscous than diesel. So, in this experimental

16

work, fuel injection pressure was investigated with increasing pressures such as 220, 240 and 260

17

bars. The primary purpose behind increasing the fuel injection pressure is to enhance the atomisation.

18

The fuel was supplied under certain pressure with the help of injection pump so that it produces

19

enough force against the spring to lift the nozzle valve and spray the fuel inside the cylinder with

20

proper atomisation. By varying the spring tensions, the injection pressure was changed. After the

21

adjustments were made in the injector, the injection pressure was tested using the injection tester as

22

shown in the figure 8. Injection timing was changed by adding or removing the shims on fuel injection

23

pump body. With 0.2 mm thickness, the Shim changed the injection timing by 1 CA. For AFIT25D, two

24

shims were added and for RFIT21D, two shims were removed. After the necessary adjustments were

25

incorporated, the experiment was conducted and the effects were assessed.

o

26 27

3. ERROR ANALYSIS:

28

The calibrated uncertainty of measuring instruments used in this experimental work is given in

29

Table 3. Ambient conditions, calibration, observations can cause an error in the experimental work.

30

Error analysis is made to validate the accuracy of the experiment by using the analysis method made

31

by (Moffat 1988). The differential method is used to carry out the error analysis based on Taylor’s

32

theorem. Error “E” as a function of Y1, Y2……..Yn can be defined as,

33 34

&[( Y1, Y2, … … Yn ] = {∈ [12 × & 12 ]3 }5/3

--- (1)

35 36

The uncertainties of performance and emission characteristics were calculated by using uncertainties

37

by different instruments which are given in Table 3. The error depends on variables Y1, Y2,……Yn which

38

can be determined by

39 4

1

∆8 8

= 9:

∆;< 3 ;<

= +:

∆;? 3 ;?

= +:

∆;@ 3 ;@

= + ⋯……+ :

5/3 ∆;B 3 ;B

= C

--- (2)

2 ∆15 D1 , E ., ∆15 is the accuracy of the measuring 5

3

Independent variables error is specified by

4

instrument, 15 is the minimum value. The overall uncertainties were calculated by using the

5

uncertainty of various measuring instruments and that can be calculated by,

6 7

GHIJKLMM = √OPG

QJRS T

8

PG

9

GHIJKLMM = √{ 0.15

3

+ G

UV

3

+ G

WU

3

+ G

XV

3

+ G

3

YRHZJ

+ PG

SKJYY[KJ T

3

3 ]MH^ KLQJ T _

+ PG

\S T

3

+

--- (3) 3

+ 0.2 3 + 0.2

3

+ 0.2

3

+ 1

3

+ 1.2

3

+ 1

3

+ 1 3 } = ±2.14

10 11 12

4. RESULTS AND CONSIDERATIONS

13

4.1. INFLUENCE OF INJECTION PARAMETERS ON BRAKE THERMAL EFFICIENCY AND BSFC

14

The performance of the compression ignition engine can be improved by changing the

15

injection parameters of the engine. In this experimental work, fuel injection pressure and fuel injection

16

timing were the two parameters chosen to enhance the performance of the engine. The performance

17

of the test engine under full load conditions is shown in the figure 9. It can be observed that the BTE

18

got increased when FIP was increased. BTE attained the threshold level of 33% at 240 bar FIP in

19

AFIT25D. The increased FIP resulted in better atomization which in turn improved the combustion

20

rate with the rise in premixed combustion phase. This helped to increase the BTE (Gumus, M et al

21

2012). For diesel, the BTE got increased from 28% to 33% under FIP (200 to 240 bar) by advancing

22

injection timing (AFIT25D). The BTE for B100 and its blends at all FIP's and FIT's got reduced which

23

could be due to high viscosity of the biodiesel that prevents air entrainment. This would have affected

24

the combustion. The low calorific value of biodiesel and its blends can also be the possible reason for

25

the decrement of BTE. The B30 blend resulted in better BTE than other blends at all FIP's and FIT's.

26

For instance, B30 yielded 2.5% increment in BTE when the injection timing was advanced in

27

comparison with standard injection at 240 bar. The increasing injection pressure is the more effective

28

way of improving the spray characteristics of the fuel with higher viscosity thus improves the BTE

29

(Agarwal, A.K et al. 2015). RFIT21D further decreased the BTE by 3.2% for 204 bar FIP when

30

compared to the advanced timing. The process of ‘advancing injection timing’ led to a large amount of

31

fuel being accumulated in the combustion chamber during long ignition delay period. This resulted in

32

rapid combustion and heat release rate with the merit of higher BTE (Agarwal, A. K et al 2013).

33

Beyond 240 bar FIP, there was a significant decrease in BTE in all the FITs since it consumed long

34

time to build up pressure (Mohan B et al. 2014). In general, the main cause of this fact is rising the

35

engine mechanical losses. The opposite trend was observed for BSFC in all the FIT's and FIP's. The

36

justifications provided earlier are for the opposite trends of BSFC. Other researchers reported that the

37

BSFC for biodiesel and its blends was higher than diesel thanks to its high density and low heating

5

1

value (Zheng M et al. 2008; Raheman H et al. 2004). Figure 10 shows the variations of BSFC in all

2

fuel modes. B30 consumed less amount of fuel than other blend ratios because the biodiesel has high

3

viscosity and less calorific value.

4

4.2. COMBUSTION ANALYSIS

5

4.2.1. HEAT RELEASE RATE ANALYSIS

6

Compression ignition engine combustion is divided into three phases such as (i) Premixed

7

combustion phase, (ii) Mixing-controlled phase and (iii) after burning. Premixed combustion takes

8

place immediately after the ID period. In this phase, high amount of heat release occurs with rapid

9

increase in pressure. The fuel gets completely vaporized during this phase and burns rapidly. The

10

heat release falls sharply once the premixed fuel and air are burnt. Then the heat release is

11

completely dependent on the fuel already present along with the fuel that is being injected into the

12

cylinder. Both of these fuels get vaporized and mix with air to form a combustible mixture. The heat

13

release rate is controlled by the rate at which the fuel vaporizes and diffuses into air to form air-fuel

14

mixture and this phase is called diffusion or mixing-controlled combustion phase (Heywood JB 1988).

15

Figure 11 shows high amount of heat released during premixed combustion stage for diesel at all

16

FIT's and FIP's. This was due to its higher calorific value and accumulation of fuel during a prolonged

17

ID period. Less amount of heat got released during premixed combustion phase for blends due to

18

high viscosity and density which resulted in poor atomization (Jayaraj S et al. 2016). Other

19

researchers also reported less premixed heat release for biodiesel (Ye P et al. 2012, Szybist JP et al.

20

2005). This was mainly due to volatile property of biodiesel (Sun J et al.2010). This led to late burning

21

with lower heat release. B30 blends resulted in high heat release among the biodiesel blends. When

22

increasing the FIP, the heat release for B30 got increased during premixed combustion phase for all

23

FIT's except RFIT21D. The increased fuel injection pressure resulted in increase in in-cylinder

24

pressure and higher premixed heat release rate. This is because increased nozzle opening pressure

25

improves the fuel atomization, which promotes the mixing and higher heat release rate (Agarwal, A.K

26

et al 2015). At high load conditions, when increasing fuel injection pressure, quantity of fuel injected

27

during the ignition delay period increased due to improved atomization of the fuel from the nozzle

28

outlet (Puhan S et al. 2009). By retarding injection timing, a short ignition delay period occurred which

29

led to lower heat release for B30. The increased FIP resulted in increased quantity of fuel injection

30

during the ignition delay period. For instance, at 260 bar FIP, the B30 blend resulted in low premixed

31

heat release (i.e., 61.1, 58, 55 J/CA deg at AFIT25D, SFIT23D, RFIT21D) due to heterogeneous

32

mixture. Some fuel mixtures get quenched on cylinder wall and do not participated in combustion,

33

thus resulting in inferior combustion. Table 4 shows the comparison of premixed heat release for all

34

FIP's and FIT's. From the Figure 11 (a, b, c, d), it is evident that during low injection pressure, the

35

duration of combustion was high because a large part of the injected fuel got burnt under mixing

36

controlled-combustion phase. During high FIP, the duration of combustion was less because the

37

premixed-combustion phase had prevailed (Can O 2014). By advancing the injection timing, a

38

maximum amount of heat release was observed for all FIP's thanks to its earlier combustion. And by

6

1

retarding injection timing, low amount of heat release was observed for all FIP's due to increased ID

2

and poor combustion.

3

4.2.3. IN-CYLINDER PRESSURE ANALYSIS

4

By varying

load, in-cylinder pressure increases during combustion. The amount of fuel

5

accumulated during the ignition delay period determines the in-cylinder pressure. The peak pressure

6

was raised for AFIT25D compared to RFIT21D as shown in the figure 12 (a, b, c and d). For biodiesel

7

blends, the ignition got started after diesel because of poor atomization and fuel-air mixture. When the

8

injection of fuel quantity was increased, the cylinder pressure also got increased. So, by raising FIP

9

up to 240 bar, the cylinder pressure also got increased. This is because of the fuel-rich mixture inside

10

the combustion chamber that resulted in rapid burning during premixed combustion phase (Agarwal,

11

A. K et al. 2013). Canakci et al. 2009 also studied the influence of injection pressure on combustion

12

behavior. They stated that increasing injection pressure resulted in an increasing in-cylinder peak

13

pressure. They attributed it owing to the enhanced atomization of the fuel at the nozzle outlet,

14

therefore more dispersed vapor phase and better combustion. For instance, 240 bar FIP and AFIT25D

15

resulted in higher cylinder pressure i.e., 83 bar for diesel and 81 bar for B30 blend. This is because of

16

the improved fuel spray pattern (Radu Rosca et al.2009) When the FIP was increased further,

17

penetration of spray was lesser due to high degree of atomization that lowered the momentum of

18

spray (Kannan GR and Anand R 2011). For instance, when FIP was increased up to 260 bar, the peak

19

cylinder pressure resulted in a slight reduction of 79.45 bar and 79 bar for diesel and B30 respectively.

20

The advancing FIT led to an increase in ignition delay due to which more amount of combustible

21

mixture in premixed combustion phase resulted in rapid combustion (Ganapathy T et al. 2011). This

22

may also be the reason for the increase in cylinder pressure. For AFIT25D and FIP 200bar, the

23

maximum pressure was increased from 79.8 bar to 81.8 bar under B30 operation. The cylinder

24

pressure got mildly reduced in blends due to poor atomization. By retarding injection timing, the

25

ignition delay was decreased where the piston reached nearer to TDC resulting in low cylinder

26

pressure. This caused large amounts of fuel getting burnt in diffusion combustion (Mohan B et al.

27

2014). By RFIT21D, the cylinder pressure obtained was away from TDC during the expansion stroke.

28

For RFIT21D and all FIP's, the pressure got mildly increased in case of diesel and got decreased in

29

case of blends.

30

4.2.3 IGNITION DELAY

31

Ignition Delay (ID) is the time period between the beginning of the injection and the start of

32

combustion. In compression ignition engines, the point of sudden change in the slope of P-theta

33

diagram is indicated as the ‘start of combustion’. Fuel injection pressure and injection timing have a

34

negligible effect on delay period. From the figure 13, it can be observed that the ID period got

35

decreased with increasing injection pressure for all FIT's up to 240 bar. The possible reason may be

36

the fine atomization of fuel droplets at high FIP's which might have led to high amount of fuel

37

accumulation in ID period (Jagannath Hirkude B and Atul Padalkar S 2014). In addition, lower sauter

38

mean diameter of fuel droplet, shorter breakup length and finer dispersion also led to decrement in ID

7

1

period (Sukumar Puhan R et al. 2009). This would have resulted in increased-premixed combustion

2

phase by burning a high portion of fuels. At FIP 260 bar, the velocity of spray penetration was high

3

which might have resulted in an improper air-fuel mixture with a long ID period. The retarded injection

4

timing has a considerable effect on ID period compared to advance injection timing. From the figure

5

13, it was observed that retard injection timing reduced the ID period. Jaichandar S et al 2012

6

observed the same due to high in-cylinder pressure and temperature. Shortest ID of 14 CA degree

7

was recorded at RFIT21D for B30 under the injection pressure of 240bar. Since AFIT25D has less

8

compression pressure and temperature, it has a long ID period due to slow evaporation rate. During

9

the injection period, the fuel gets accumulated until it reaches the self-ignition temperature and rapid

10

combustion occurs once the fuel attains the self-ignition temperature. Due to lengthy ID period, the

11

cylinder pressure was high for AFIT25D compared to RFIT21D. It can also be observed that the diesel

12

resulted in less ID when compared to biodiesel blends. This might be attributed to mild higher density

13

and viscosity of biodiesel (Muralidharan K et al.2011).

14

4.4. EMISSION ANALYSIS

15

The compression engine emitted due to a non-homogeneous mixture of air and fuel. This uneven air

16

fuel mixture led to the formation of emission that was primarily dependent on power stroke and prior

17

to exhaust valve opening. Ignition delay, fuel injection pressure, fuel injection timing, fuel injection

18

quality and duration of expansion stroke played a vital role in the production of emissions.

19

4.4.1. HC EMISSION ANALYSIS

20

Hydrocarbon emission from the diesel engine is mainly due to overmixing or under mixing of

21

air and fuel and further due to large-sized fuel droplets (Heywood JB 1988). From the figure 14, it can

22

be observed that the hydrocarbon emissions were decreased with increasing fuel injection pressure

23

up to 240 bar because of good air fuel mixture. Other researchers Kuti O.A et al. 2011 and Zhang G et

24

al. 2012 also obtained similar results. Beyond injection pressure of 240 bar, the hydrocarbon emission

25

got increased due to incomplete combustion resulting in low peak heat release rate and peak

26

pressure. It is known that increasing fuel injection pressure directed to fine spray. However, speed and

27

range to which the fuel spray penetrates into the compressed air envelop has a better stimulus on air-

28

fuel mixing and combustion (Heywood JB 1988). The increased injection pressure increases the

29

distance of spray penetration length, which further increases the chances of wall impingement

30

(Lahane, S et al 2014). At full load conditions, the fuel-air mixture was very lean which led to less

31

propagation of flame through mixture. However, partial oxidation took place, which resulted in

32

hydrocarbon emissions. In addition to this, impingement of fuel particles on cylinder wall reduces the

33

air-fuel mixing rate that rises the formation of unburnt hydrocarbon (Kiplimo R et al.2012). It was

34

observed that, by increasing the biodiesel blends, hydrocarbon emissions got decreased for all FIP's

35

and FIT's. This could be due to high oxygen content in biodiesel. By Advancing injection timing, more

36

time could be made available for air-fuel mixing. This was followed by earlier beginning of combustion,

37

resulting in superior combustion with less amount of hydrocarbon emissions. The earlier start of

38

combustion generates more in-cylinder temperature, resulting in complete oxidation with decreased

8

1

hydrocarbon emissions and reduces the flame quenching layer thickness (Sayin Cenk et al.2008). For

2

AFIT25D, Syzygium cumini biodiesel and its blends mildly reduced the hydrocarbon emissions for all

3

FIP's. By retarding injection timing, the lack of time available for air-fuel mixing resulted in poor

4

vaporization, which led to larger fuel droplets. From the results, it is observed that, unburnt HC

5

emissions were increased for RFIT21D, when compared to AFIT25D and SFIT23D.

6

4.4.2. NITROGEN OXIDE EMISSION ANALYSIS

7

NO refers to Nitric Oxide emissions, a function of in-cylinder temperature. Latent heat of vaporization

8

is the primary property of NO emission. If the fuel has more latent heat of vaporization, then the fuel

9

absorbs more heat energy during the delay period. This resulted in reduced in-cylinder temperature

10

and accordingly reduced NO emission (Heywood JB 1988). But, in the current study, ignition delay is

11

primarily due to variations in FIT's and FIP's. Therefore, the latent heat of vaporization may not be the

12

main criteria for NO emissions. From the figure 15, it can be observed that the NO emissions for all

13

fuel modes were increased up to FIP of 240 bar. By Increasing FIP, as discussed earlier the

14

atomization got improved resulting in quick and higher combustion temperature. In addition to this,

15

from the Figure 11, it can be observed that premixed HRR is maximum at AFIT25D with 240 bar FIP.

16

This trend of heat release rate is converted hooked on high NO emissions. Generally, NO emissions

17

increase when the in-cylinder temperature increases. On further increasing FIP (260 bar), the NO

18

emissions got decreased due to less heat release rate (see figure 11). The NO emissions were high

19

for B100 and its blends (14.5 g/kWh) compared to diesel at all FIP's and FIT's. The increased blends

20

led to an increase in NO formation due to higher oxygen content in biodiesel and its blends (Tuccar.G

21

et al. 2014 and Altaie M.A.H et al.2015). It can be attributed to the accepted NO formation mechanism

22

by Zeldovich,

23

resulted in lengthy ignition delay (see figure 13). In case of long delay period, a greater portion of the

24

fuel gets injected inside the cylinder and has enough time to mix with air due to which the amount of

25

premixed portion of fuel becomes higher before ignition. NO formation is related to premixed portion

26

of the fuel. By advancing injection timing, the combusted fuel particles remain in the cylinder and the

27

heat released from cylinder wall is responsible for in-cylinder temperature resulting in NO formation.

28

At FIP 240 bar, the heat release rate (62 J/deg CA) was more for AFIT25D i.e., higher NO emission

29

from diesel fuel engine. As injection timing got retarded, the opposite effect was also experienced. For

30

RFIT21D, ignition delay tended to be shorter and ultimately, the premixed portion of the fuel got

31

reduced. Reducing the premixed portion of fuel led to lower NO formation (Mani M and Nagarajan

32

2009) and can be observed from the figure 15.

33

4.4.3. CO EMISSION ANALYSIS

34

The CO gets emitted due to the lack of oxygen content at the time of combustion. CO can kill humans

35

by displacing oxygen in their blood vessels. It is produced mainly due to incomplete combustion,

36

which is exacerbated in the absence of oxidants, temperature and residence time. At the end of

37

combustion, the CO must get oxidized to CO2 for the process to complete. If it does not occur due to

38

lack of oxidants, CO is produced (Heywood JB 1988). From the figure 16, it can be observed that the

3

+ c3 ↔ c + c (Arul Mozhi Selvan V et al. 2014). Advancing the injection timing

9

1

increase in FIP up to 240 bar, mildly decreased the CO emissions whereas at FIP 260 bar, it got

2

increased. Same trend was observed for Mohan.B et al. 2014. Inherently, when increasing nozzle

3

opening pressure, fine atomization occurs resulting superior combustion. But the engine speed and

4

limit of spray penetration have greater influence on air-fuel mixture and combustion. When FIP is

5

increased, it resulted in increased spray penetration resulting in wall quench. It can also be observed

6

that the CO emissions got decreased for B100 and its blends compared to diesel. This might be due

7

to increased oxygen content in blends which increased the oxidation rate (Taghizadeh-Alisaraei A and

8

Rezaei-Asl A 2016). AFIT25D resulted in less CO emissions compared to SFIT23D and RFIT21D for

9

all FIP’s due to high cylinder temperature and increased oxidation. The retarded fuel injection timing

10

increased the CO emissions compared to SFIT23D and RFIT21D. This might be due to wall

11

impingement that resulted in poor mixing of air and fuel in association with increased CO formation

12

(Kiplimo R et al. 2012).

13

4.4.4. SMOKE EMISSION ANALYSIS

14

The diesel engine produces smoke due to inferior combustion resulting from over-rich AFM

15

ratio or partially evaporated fuel (Henein NA and Bolt 1972; Shipinski et al. 1968; Grigg and Syed

16

2006). From the figure 17, it can be observed that the smoke emission got decreased when

17

advancing the fuel injection timing whereas it got increased while increasing injection pressure. When

18

increasing FIP, the fuel droplets attains nanostructure size and unable to find air to form a

19

homogeneous mixture, resulting in incomplete combustion due to the reduction of local air-fuel

20

mixture. When advancing FIT, low amount of smoke emissions was observed due to release of high

21

amount of heat during the premixed combustion phase. For AFIT25D, more amount of fuel got

22

accumulated during long ignition delay period. In order to have superior combustion, it is appropriate

23

to mix qualified air and fuel during long ignition delay period. Therefore, the heat release rate for

24

premixed combustion phase was higher which may be the root cause for less smoke. Smoke

25

formation for B30 fuel was less than all other blends and diesel. The oxygen content available in B30

26

helped in oxidation to attain superior combustion with less smoke formation. However, increasing

27

blends emitted more smoke than B30 and diesel. The high viscosity-blends produced locally rich

28

mixture in the combustion chamber that might have emitted more smoke. Concerning retarding

29

injection timing, the smoke emissions became higher than AFIT25D and SFIT23D. Fuel was injected

30

close to TDC when less time was available for heat release. The mixing-controlled combustion phase

31

occurred earlier that led to high smoke emission.

32

5. OPERATING COST ANALYSIS

33

The operating cost analysis of the experiment is tabulated in table 5. It is clear that the

34

conventional engine operated with diesel, biodiesel and SCO incurred highest operating costs

35

compared to engine operated under advancing fuel injection parameters. A 33.8% decrease in

36

operating cost was recorded in SCO under advancing fuel injection parameters. However, the SCO

37

emitted more amount of smoke and NO compared to biodiesel blends (B30 and B70). In India, diesel

38

and petrol prices are fixed daily under ‘daily dynamic pricing regime’ for the last few years. According

10

1

to financial experts, the lower rupee value and higher excise duty decides the price of petrol and

2

diesel. Indian National Congress, a political party in India posted a graph in its official twitter handle on

3

diesel prices as reproduced in figure 1 (News18 2018). The graph shows the percentage increase in

4

petrol price with percentage change in international crude oil. Petrol prices rose by 20.5% between

5

2004 and 2009 and up to 75.8% from 2009 to 2014. However, petrol prices have risen by 13% even

6

though the crude oil prices dropped by 34%. This hike in petrol and diesel prices had a direct impact

7

on daily consumables. As a final point, SCO seems to be a cost-effective fuel alternative that could be

8

used for agricultural purposes though inferior performance and stringent emissions are its drawbacks.

9

The widespread production of SCO will reduce the imports of crude oil and increase the livelihood of

10

farmers.

11

5. CONCLUSION

12

The experiments were conducted in a single cylinder direct-injection compression ignition

13

engine at a constant speed of 1500 RPM with 100% constant load. The engine was fueled with neat

14

diesel, B30, B70 and B100. The study discussed the performance, combustion and emission behavior

15

by varying the fuel injection pressures and fuel injection timings. The following conclusions were

16

drawn from the experimental work

17

•

BTE got decreased for both SFIT23D and RFIT21D, whereas at AFIT25D, BTE for neat diesel

18

got increased to 33% from 29.5% for FIP of 200 to 240 bar. By AFIT25D, a large amount of

19

fuel got accumulated during the long ignition delay resulting in rapid combustion and rapid

20

heat release rate increasing BTE. In B30 blend, 3% improvement in BTE was noticed. BSFC

21

got reduced by 2.02% for B30 for AFIT25D and FIP240. So, the AFIT25D and FIP of 240 bar

22

are found to be optimized conditions for higher BTE.

23

•

24 25

The optimized FIP is 240 bar. Beyond 240 bar, BTE got decreased because less time was required to build up the pressure.

•

At AFIT25D and 240 bar FIP, maximum heat release 65 J/deg CA was observed for all FIP’s

26

and by RFIT21D, lower heat release was observed. The maximum pressure obtained was

27

82.5 bar under neat diesel for AFIT25D and 200 bar FIP.

28

•

For B100, the formation of HC and CO for AFIT25D and 240 bar FIP were found to be 47%

29

and 10% less than SFIT23D and 200 bar FIP. A 3.6% reduction in smoke emission was

30

observed for AFIT25D and 240 bar FIP than other standard injection conditions (i.e., SFIT23D

31

and FIP 200bar). However, NO emissions were higher for AFIT25D with 240 bar FIP.

32

To conclude, advancing injection parameters were effective in achieving the reduced emissions and

33

superior performance of Kirloskar-made single cylinder diesel engine with extra benefit on operating

34

cost. The study revealed that the B30-fueled engine emitted less smoke opacity compared to diesel

35

and all other blends. However, when considering operating cost, SCO seems to be the cost-effective

36

fuel with highest level of emissions, which can be improved by utilization of gaseous fuels under dual

37

fuel mode. Further, NO emission can be eliminated under bio fueled operation by implementing

38

Exhaust Gas Recirculation (EGR).

11

1

Acknowledgements

2

The author would like to thank the DST (Department of science and technology), New Delhi India, for

3

financial support provided for the above investigations. This research work was supported by the DST

4

fund under the project SB/ EMEQ-180/2014 dated 08.03.2016.

5

Nomenclature: AFIT25D SFIT23D RFIT21D FIT FIP B30

: : : : : :

Advancing fuel injection timing at 25 degrees crank angle Static fuel injection timing: 23-degree crank angle Retarding fuel injection timing at 21 degrees crank angle Fuel injection timing Fuel injection pressure 30% biodiesel blended with 70% diesel

B70 B100 SCO HC CO NO CO2 CA BTE BSFC AFM ID HRR P

: : : : : : : : : : : : : :

70% biodiesel blended with 30% diesel 100% biodiesel (SCO) Syzygium cumini oil Hydrocarbon Carbon monoxide Nitrogen oxide Carbon-di-oxide Crank angle Brake thermal efficiency Brake specific fuel consumption Air fuel mixture Ignition delay Heat release rate Pressure

6 7

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Zhu, L., Cheung, C.S., Zhang, W.G., Huang, Z., 2010. Emissions characteristics of a diesel engine operating on biodiesel and biodiesel blended with ethanol and methanol. Sci Total Environ;408:914–21. https://doi.org/10.1016/j.scitotenv.2009.10.078

Table 1 Physical and chemical properties of fuels Fuel characteristics 3

Density g/cm at o x0 C Kinematic 2 viscosity (mm /s) o 40 C Calorific value (MJ/kg) Cetane index o

Flash point ( C)

Testing methods

DIESEL

B30

B70

B100 (This study)

B100 (Chuah, L.F et al., 2015)

B100 (Nisar et al., 2018)

ASTM D4502 ASTM D446

0.850

0.855

0.861

0.866

0.88

0.884

2.5

3.6

4.5

5.24

4.62

6.1

ASTM D4868 ASTM D2699 ASTM D93

42.95

42.59

42

41.93

39.4

39.99

47

48

49

55

60

64

50

67

100

173

135

204.5

15

Acid value mg KOH/g

ASTM D974

0.003

0.08

0.1

0.3

0.30

0.025

Iodine value g Iodine/100 g

-

-

-

-

95

57.64

109

1 2 3 4 5 6 7 8 Table 2 Engine specifications.

Make & model Compression ratio Type of stroke Bore & stroke Rated output Maximum speed Torque at full load Crankshaft center height Static fuel Injection timing Type of Fuel injection Injection pressure Cubic capacity Type of cooling Type of loading No. of cylinders

Kirloskar and AV-1 16.5 : 1 4 80 x 110mm 3.7 (5) kW(hp) 1500 rpm 0.024 kN-m 203 mm o 23 BTDC Direct injection 200 bar 0.553 ltr Water cooled Eddy current dynamometer 1

9 Table 3 Range, accuracy and uncertainty of instruments. Measurement devices K type thermometer

Parameter

Range

Accuracy

Uncertainity

Temperature

0-900 C

AVL Digas 444 analyzer AVL Digas 444 analyzer AVL Digas 444 analyzer AVL 437C smoke

±1°C

±0.15%

CO

0-10% by vol

±0.2%

HC

0-20000 ppm by vol 0-5000ppm by vol 0-100% opacity

<0.6%vol:±0.03%vol ≥0.6%vo :±5%vol <200ppm vol:±10ppm vol≥200ppm vol:5% <500ppm vol:±50ppm vol≥500ppm vol:±10 ±0.2%

NO Opacity

o

16

±0.2% ±0.2% ±1.0%

meter Piezo electric pressure transducer Eddy current dynamometer Bure5e and stop watch

In-cylinder pressure Brake power

1-100 bar

±0.1 bar

±1.2%

0-50 kW

±0.5 kW

±1%

Fuel flow rate

0-200 g

0.5 g

±1%

1 2 Table 4 Comparison of premixed heat release for all FIP’s and FIT’s. FIP 200 220 (bar) FIT AFIT25D SFIT23D RFIT21D AFIT25D SFIT23D D (J/degCA) B30 (J/deg CA) B70 (J/deg CA) B100(J/degCA)

62.8 62.2 61.9 61.5

61 60.5 59.8 58.6

57 56.5 56.3 54

63.6 63.4 63 62.8

62.5 61.8 61.2 60.7

240

260

RFIT21D

AFIT25D

SFIT23D

RFIT21D

AFIT25D

SFIT23D

RFIT21D

60 59.5 58.2 57.35

65 64 63.5 63.2

63 62.7 62.4 62

61.7 61 60.5 60

61.9 61.1 60.7 60

60 58 58 57.3

56.5 55 54.2 53

3 4 5 Table 5 Compara?ve summary of injec?on pressure and ?ming strategies. FIT

SMOKE

CO

NO

HC

BTE

FIP

RFIT21D

SFIT23D

AFIT25D

260

240

220

200

200

200

220

240

260

D B30 B70 B100

▼1.82% ▼3.72% ▼3.89% ▼8.00%

▲3.57% ▲1.00% ▼1.92% ▼4.00%

▼1.78% ▼3.70% ▼3.84% ▼6.00%

▼5.35% ▼7.40% ▼9.61% ▼10.00%

28 27 26 25

▲3.57% ▲1.85% ▼3.84% ▼6.00%

▲10.71% ▲9.25% ▲5.76% ▲4.00%

▲17.85% ▲16.66% ▲9.61% ▲8.00%

▲5.35% ▲3.70% ▼1.92% ▼4.00%

D B30 B70 B100 D B30 B70 B100 D B30 B70 B100 D B30 B70 B100

▲104.34% ▲125.00% ▲141.17% ▲192.30% ▼23.93% ▼24.52% ▼20.68% ▼19.30% ▲42.24% ▲45.41% ▲50.98% ▲63.60% ▲48.33% ▲46.42% ▲46.29% ▲40.00%

▲21.73% ▲30.00% ▲41.17% ▲61.53% ▲4.34% ▲2.56% ▲6.03% ▲3.07% ▲40.51% ▲41.81% ▲49.01% ▲52.27% ▲33.33% ▲32.14% ▲31.48% ▲34.00%

▲39.13% ▲40.00% ▲41.17% ▲53.84% ▼6.52% ▼0.94% ▼0.80% ▼3.84% ▲43.10% ▲45.45% ▲52.94% ▲61.36% ▲18.66% ▲19.64% ▲18.51% ▲22.00%

▲52.17% ▲60.00% ▲64.70% ▲92.30% ▼21.73% ▼19.81% ▼18.10% ▼19.23% ▲50.00% ▲50.90% ▲56.86% ▲68.18% ▲9.66% ▲7.14% ▲1.85% ▲2.00%

0.023 0.02 0.017 0.013 9.2 10.6 11.6 13 0.58 0.55 0.51 0.44 60 56 54 50

▼13.04% ▼10.00% ▼11.76% ▼7.69% ▲19.56% ▲17.92% ▲16.37% ▲13.07% ▼5.17% ▼10.90% ▼9.80% ▼6.81% ▼16.66% ▼16.07% ▼20.37% ▼18.00%

▼21.73% ▼25.00% ▼23.52% ▼23.07% ▲30.43% ▲29.24% ▲25.00% ▲19.23% ▼15.51% ▼16.36% ▼13.72% ▼11.36% ▼20.83% ▼19.64% ▼24.07% ▼21.00%

▼34.78% ▼40.00% ▼41.17% ▼46.15% ▲41.30% ▲34.90% ▲31.03% ▲26.92% ▼18.96% ▼20.00% ▼19.60% ▼15.90% ▼23.33% ▼25.00% ▼28.70% ▼27.00%

▲30.43% ▲40.00% ▲41.17% ▲69.23% ▲14.13% ▲14.15% ▲13.79% ▲11.53% ▼12.06% ▼10.90% ▼7.84% ▼2.27% ▼20.00% ▼19.65% ▼24.00% ▼25.00%

6 7 Table 6 Opera?ng cost analysis.

17

TEST FUEL

LOAD (kW)

MARKET PRICE * (USD) (avg)

DIESEL B30 B70 B100

3.7 3.7 3.7 3.7

0.98 0.854 0.686 0.56

STANDARD FUEL INJECTION ADVANCED FUEL INJECTION PARAMETERS PARAMETERS o o SFIT : 23 BTDC; FIP : 200 bar AFIT : 25 BTDC; FIP : 240 bar Kg/h USD/h Kg/h USD/h 0.978 0.815 0.81 0.675 0.99 0.761 0.905 0.696 1 0.624 0.985 0.615 1.512 0.783 1 0.518 * Chennai (April 2018-Feb 2019), India.

1 2 3 4 5 6 7 8 9 10 11 12 13 14

FIGURES:

18

Fig.1: Soxhlet apparatus 1

Fig.2: Oil yield for different solvents 2

19

Fig.3: Syzygium cumini oil extracCon process

Fig.4: FTIR Spectrum of Syzygium Cumini oil 1 2

20

Fig.5: Syzygium Cumini Biodiesel production 1 1. Load indicator 2. Diesel tank 3. SCO tank 4. Fuel injector 5. Pressure transducer 6. Intake manifold AIR 7. Exhaust manifold 8. Crank angle encoder 9. Combustion Analyser 10.Charge amplifier 11.Data acquisition system 12.Di gas analyser 13.Smoke meter 14.Engine 15.Water in 16.Water out 17.Test bench

11 2

3

5 6

9

10

12

7

4

16 13 1

15

16 8 2 14

15

17

Fig.6: SchemaCc diagram of experimental arrangement 2

21

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Fig.7: Test bench

(a) Nozzle tester (b) InjecCon pump Fig.8: Varying injecCon pressure and injecCon Cming

Fig.9: Influence of injecCon parameters on Brake thermal efficiency 30

22

Fig.10: Influence of injecCon parameters on Brake specific fuel consumpCon 1 2 3 4 5 6 7 8 9 10 11 12 13 14 (a)

23

(b)

(c)

(d)

24

Fig.11: VariaCons in HRR with varying fuel injecCon Cmings for different biodiesel blends at (a) 200, (b) 220, (c) 240 and (d) 260 bar FIPs 1 2

(b)

(a)

(d)

(c)

Fig.12: In-cylinder pressure variaCons for different injecCon pressures and injecCon Cming 3

25

Fig.13: Influence of injecCon parameters on IgniCon delay 1

Fig.14: Influence of injecCon parameters on HC emissions 2

Fig.15: Influence of injecCon parameters on NO emissions 3 4

26

Fig.16: Influence of injecCon parameters on Carbon monoxide emission 1

Fig.17: Influence of injecCon parameters on Smoke emissions 2 3 4

27

Fig.18: % increase in petrol prices with % change in InternaConal crude oil prices at retail selling price in Delhi, India (Business today magazine dated sep-11/2018). 1 2 3

28

Declaration of interests ☐ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☒The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:

DST (Department of science and technology), New Delhi India. SB/ EMEQ-180/2014 dated 08.03.2016.

We the undersigned agree with all of the above.

Author’s name 1. KARTHIC SV 2. M SENTHIL KUMAR 3. G.NATARAJ 4. S VINOTH KUMAR 5. P PRADEEP 6. R PRADEEP