60

CHAPTER 5

MATERIALS AND METHODS

5.1 MATERIALS

Fuels used in this study are diesel, neem oil, ethanol, 1-propanol,

1-butanol, 1-pentanol, diethyl ether, dimethyl carbonate and diglyme. Diesel

fuel has been obtained from local filling station and used for reference. The

raw oil has been purchased from local shops. Methanol (99% purity),

concentrated sulphuric acid (98% purity), potassium hydroxide (97% purity)

and distilled water, purchased from Scientific MERCK Company have been

obtained to produce methyl ester from neem oil. Other fuels, the ethanol,

1-propanol, 1-butanol, 1-pentanol, diethyl ether, dimethyl carbonate and

diglyme have been purchased from Scientific MERCK Company.

5.2 BIODIESEL PRODUCTION AND ANALYSIS

5.2.1 Transesterification Setup

The setup (Figure 5.1) in which biodiesel prepared consists

of round bottle flask, condenser, magnetic stirrer/paddle, dimmer start,

thermometer, measuring jars and separating funnel. Openings are provided in

the round bottom flask for connecting condenser and temperature sensor. The

heater coil surrounds the reactor vessel and it provides uniform heating all

round the flask. The magnetic stirrer enables proper mixing of the NeO and

methanol. The speed of the stirrer is adjustable. Dimmer start is used to

61

control the voltage so that constant temperature can be maintained. Condenser

is used to condense alcohol if it vaporizes from the mixture. Separating funnel

helps to separate the biodiesel from glycerol.

Figure 5.1 Transesterification setup

The crude NeO used is dark brown in color. The free fatty acid

content (FFA) of the NeO has been determined by standard titration. The acid

value of the oil is 14.88 mg KOH/g and the FFA value of 7.44%. As it is far

above the limit for an alkaline catalyst, pretreatment process is necessary to

reduce the FFA level in order to get high yield of biodiesel.

In pretreatment process, 1000 ml NeO is heated to about 50oC, 250

ml methanol is added and stirred at 750 rpm for a few minutes. With this

mixture 2% vol. H2SO4 is added and stirred at a constant temperature of 50oC

for an hour. After the reaction, the solution is allowed to settle for 24 hrs in a

separating funnel. The excess alcohol along with sulphuric acid and

62

impurities floats at the top surface and is removed. The lower layer is

separated for further processing (alkaline esterification).

In alkaline esterification, several factors such as amount of catalyst,

reaction temperature, molar ratio of methanol to oil and reaction time could

influence the transesterification process because of different content of

triglycerides and phospholipids. In this study, three of the most important

parameters namely, catalyst concentration, temperature and time of reaction

which affect the yield of the transesterification process have been considered.

Moreover, these are the easiest factors which can be carefully controlled

during the industrial production (Ferella et al 2010).

The Design expert software, version 8.0 has been used to build the

experimental plan for RSM. The experimental design for the factors used in

the conversion of biodiesel is obtained by RSM, with 3-factor and 2-level

central composite design. The factors selected are: KOH concentration in the

range of 3 - 7 mg; reaction temperature in the range of 50 - 60oC; and reaction

time in the range of 30 - 90 min. The range of KOH, reaction time and

reaction temperature are chosen based on the preliminary studies conducted in

our laboratory. Conversion is selected as the response variable. In this study, a

set of 20 experiments including the 23 factorial experiments, 6 star points

coded as and 6 center points are carried out.

Response surface plots are developed using the fitted polynomial

equation obtained from the regression analysis, holding one of the

independent variables at constant values and changing the other two variables

as shown in Figures 5.2-5.3. The quality of the fit of the polynomial model

equation has been evaluated by the coefficient of determination R2, and its

regression coefficient significance has been checked with F-test with a

63

confidence level of 95%. All the graphs have curvilinear in profile in

accordance with quadratic model.

Figure 5.2 Response surface of yield of biodiesel in percentage with

catalyst and reaction time

Figure 5.3 Response surface of yield of biodiesel in percentage with

reaction temperature and reaction time

Figure 5.2 shows the effect of KOH and the reaction time on the

conversion of biodiesel at a constant temperature of 55oC. The conversion of

30.00 36.00

42.00 48.00

54.00 60.00

66.00 72.00

78.00 84.00

90.00

3.00

4.00

5.00

6.00

7.00

40

50

60

70

80

90

100

YIELD

A: KOH C: TIME

30.00 36.00

42.00 48.00

54.00 60.00

66.00 72.00

78.00 84.00

90.00

50.0052.00

54.00 56.00

58.00

60.00

70

75

80

85

90

95

100

YIELD

B: TEMPERATURE C: TIME

64

biodiesel is increased initially with the simultaneous increase of KOH

concentration and reaction time, reaches maximum level at intermediate

reaction time (60 min) and intermediate KOH (5 mg) and then decreases with

the increase of KOH concentration and reaction time. This may be due to the

fact that the excess KOH concentration can produce emulsions and it is

difficult to separate the biodiesel from the glycerol (Giovanilton Silva et al

2011).

It is also possible to achieve higher yield with the increase of

reaction time at lower concentration of KOH. Thus reaction time is also the

important factor in achieving the higher conversion of biodiesel. The same

observation can also be made from Figure 5.3, which shows the effect of

reaction temperature and the reaction time on the conversion of biodiesel at a

fixed concentration KOH of 5 mg. Comparing the results presented in Figure

5.2 and Figure 5.3, the optimum values of the factors are found to be 5 mg

KOH concentration, 550C reaction temperature and 60 min reaction time for

the maximum yield of 93%. Ferella et al. (2010) have studied the

transesterification reaction of rapeseed oil and achieved the best results at

reaction temperature of 500C and reaction time 90 min. However, the

transesterification reaction may require different temperatures and different

times, depending on the oil used. The flow chart for NOME production is

given in Figure 5.4.

65

1. Acid Transesterification

Methanol H2SO4

Heating ( with 55oC) with Constant Stirring (Duration: 1hr)

Separation of reaction mixture

Excess alcohol + H2SO4 (Upper

layer)

KOHMethanol

Heating (with 55oC) with Constant Stirring (Duration: 1hr)

Separation of reaction mixture

Lower layer

Evaporation of Methanol

Washing and Purification

NOME (Biodiesel) Upper layer

NeO

2. Alkaline Transesterification

Figure 5.4 Flow diagram for biodiesel production

5.2.2 Analysis of Biodiesel

Methyl ester of Azadirachta indica is characterized by Fourier

Transform Infrared spectroscopy (FTIR), proton Nuclear Magnetic Resonance

(1H NMR) and carbon Nuclear Magnetic Resonance spectroscopy

(13C NMR). The FTIR in the mid infra red region is used to identify the

functional groups and the bands corresponding to various stretching and

bending vibrations in the samples of oil and biodiesel. The NMR is one of the

66

most powerful techniques used to determine structure of the chemical

compounds. The NMR technique is suitable for monitoring the

transesterification reaction.

Methyl ester of NeO has been characterized by FTIR using

Shimadzu, IR-Affinity-1 model and detector of DLATGS in the range 400-

4000 cm-1. The resolution is 1cm-1 and 20 scans.1H NMR analysis has been

performed on an Avance 400 MHz spectrometer equipped with 5 mm BBO

BB-1H probes. Deuterated chloroform (CDCl3) and TMS have been used as

solvent and internal standard respectively. A 1H NMR (400 MHz) spectrum

has been recorded with pulse duration of 30o, a relaxation delay of 1.0 s and

27 scans. The 13C (75 MHz) spectra has also been recorded with a pulse

duration of 30o, a relaxation delay of 1.0 s and 120 scans.

5.2.2.1 FTIR Analysis

Figure 5.5 and Figure 5.6 show the FTIR spectra of NeO and

NOME respectively. It can be observed from Figure 5.5-Figure 5.6 that the

absorption bands are observed at about 2927 cm-1, which correspond to H-C=

group, and between 2927 cm-1 and 2855 cm-1 for the –CH2- group, about

1735 cm-1 for the carbonyl group and at 766 cm-1, which correspond to –

(CH2)n- sequence of aliphatic chains of fatty acids.

The FTIR spectra of NeO and NOME show almost similar

characteristics because they have almost the same chemical compounds.

However, small differences have been observed. In the spectrum of NOME

shown in Figure 5.6, the (C=O stretch) band of methyl ester is observed at

1732 cm-1 (Umer Rashid et al 2011). The band that has been observed in the

spectrum of NOME is at 1176-1230 cm-1, which is attributed to methyl groups

near carbonyl groups. The other characteristic peak was observed at

67

2918 cm-1, which is the characteristic of fatty acid methyl esters (Umer

Rashid et al 2011).

Figure 5.5 FTIR spectra of NeO

Figure 5.6 FTIR spectra of NOME

68

5.2.2.2 1H NMR Analysis

Figure 5.7 and Figure 5.8 show the 1H NMR spectrum of NeO.

Figure 5.9 and Figure 5.10 show the 1H NMR spectrum of NOME. Figure 5.8

and Figure 5.10 show the enlarged view of the spectrum of NeO and NOME

respectively. From Figure 5.7 and Figure 5.8, in the 1H NMR spectrum of

NeO, the presence of the triacylglycerides can be observed by the multiplets

identified in the range of 4–4.5 ppm.

From Figure 5.9 and 5.10, in the 1H NMR spectrum of NOME, the

biodiesel production can be confirmed through the disappearance of the signal

between 4.22 – 4.42 ppm and the appearance of a new signal at 3.68 ppm.

From Figure 5.9 and Figure 5.10, the 1H NMR spectrum of NOME shows a

triplet of -CH2 protons identified at 2.3 ppm and also confirms the presence

of methyl ester in the prepared biodiesel. The 1H NMR spectrum of NOME

(Figure 5.9 and Figure 5.10) shows a triplet near 0.8 ppm and at 1.2 ppm, and

a strong signal at 2.3 ppm, which correspond to terminal methyl hydrogens

and methylenes of hydrocarbon moieties in the biodiesel.

From Figures 5.7-5.10, the terminal methyl hydrogens of the fatty

acid chains are observed at 0.89 ppm. The signals between 1.2 and 2.3 ppm

are attributed to the methylene internal hydrogen atoms of the triglyceride

fatty acid chains. The olefinic hydrogens are identified at 5.34 ppm.

(Monterio et al 2009; Souza 2007).

69

Figure 5.7 1H NMR spectra of NeO

Figure 5.8 Enlarged view of 1H NMR spectra of NeO

70

Figure 5.9 1H NMR spectra of NOME

Figure 5.10 Enlarged view of 1H NMR spectra of NOME

71

5.2.2.3 13C-NMR Analysis

The 13C NMR spectrum of the NeO and NOME is shown in

Figure 5.11 and Figure 5.12 respectively, which show the characteristic peaks

of ester carbonyl (-COO-) and C-O at 174.17 and 51.29 ppm respectively.

From Figure 5.12, the signals identified at 24 to 34 ppm are attributed to

methylene carbons of long carbon chain in fatty acid methyl esters (FAMEs).

Figure 5.11 13C-NMR spectra of NeO

The unsaturated carbon appears between 127 and 130 ppm. From

Figure 5.12, the disappearance of signal at 62 and 68 ppm and the appearance

of a new signal at 51 ppm is due to CH2 carbon in the prepared biodiesel. The

signals of the ester group carbon are located at approximately 174 ppm. From

Figure 5.12, the signals at 174 ppm and 51 ppm confirm the success of the

transesterification reaction (Tai-Yow et al 1989; Wei-chang Fu et al 2009). In

addition to this, various signals correspond to the internal CH2, have been

observed between 22 and 34 ppm as shown in Figure 5.11 and Figure 5.12.

72

Figure 5.12 13C-NMR spectra of NOME

5.3 ENGINE SETUP

Experiments have been conducted in a single-cylinder, four-stroke,

naturally aspirated, direct injection diesel engine. The specification of the

engine is given in Table 5.1 and the experimental setup is shown in

Figure 5.13. Two separate fuel tanks with a fuel switching system are used,

one for diesel and the other for biodiesel and other test fuels. Fuel

consumption is measured using optical sensor. A differential pressure

transducer is used to measure airflow rate. Engine is coupled with an eddy

current dynamometer to control engine torque through computer. Engine

speed and load are controlled by varying excitation current to eddy current

dynamometer using dynamometer controller. A piezoelectric pressure

transducer is installed in engine cylinder head to measure combustion

pressure. Signals from pressure transducer are fed to charge amplifier. A high

precision crank angle encoder is used to give signals for top dead centre and

crank angle. The signals from charge amplifier and crank angle encoder are

supplied to data acquisition system. An AVL exhaust gas analyzer and AVL

73

smoke meter are used to measure emission parameters and smoke intensity

respectively. Thermocouples (chrommel alumel) are used to measure exhaust

temperature, coolant temperature and inlet air temperature. The

instrumentation details are explained in following subsections.

Table 5.1 Engine specifications

Make and Model Kirloskar –TV 1

HP and Speed 5 HP and 1500 rpm

Type of engine Single cylinder, 4 Stroke DI

Type of fuel injection Pump-line-nozzle injection system

Nozzle type Multi hole (3 holes)

Piston type Bowl-in-piston

Compression ratio 16.5:1

Bore and Stroke 80 mm and 110 mm

Load indicator Digital, range 0-3.5 kW

Method of loading Type-eddy current dynamometer

Method of starting Manual cranking

Method of cooling Water

Load sensor Strain gauge load cell

Fuel flow sensor Optical sensor

Air flow sensor Pressure transducer

Temperature sensor K-type thermocouple

Type of ignition Compression ignition

Injection timing and pressure 23 o before TDC and 210 bar

Lube oil SAE40

74

5.3.1 Eddy Current Dynamometer

An eddy current dynamometer of 5 HP (Maximum speed 300

rev/m) capacity is directly coupled with the engine. The engine and air cooled

eddy current dynamometer are coupled using tyre coupling. The output shaft

of the eddy current dynamometer is fixed to a strain gauge type load cell for

measuring the applied load to the engine. The load to the engine can be varied

by operating the potentiometer provided on the panel or through computer.

1 – Air Flow Sensor 2 – Fuel Flow Sensor 3 – Pressure Sensor 4 – Diesel Tank

5–Fuel Blends Tank 6– Five Gas Analyzer 7 – Smoke Meter 8 – Speed Sensor

9 – Crank Angle Encoder

Figure 5.13 Experimental setup

5.3.2 Air Flow Sensor

The air flow to the engine is routed through cubical air tank. The

rubber diaphragm fixed on the top of the air tank takes care of neutralizing the

75

pulsation for airflow measurement. The inlet air tank is provided with an

orifice.

The pressure drop across the orifice is measured using a differential

pressure transducer. The differential pressure sensor gives a proportional

voltage output with respect to the difference in pressure. The output of the

differential pressure transducer is amplified using an instrumentation

amplifier and fed to the data acquisition card.

5.3.3 Fuel Flow Sensor

The fuel from the tank is connected to a solenoid valve. The outlet

of solenoid valve is connected to a glass burette and the same is connected to

the engine through a manual ball valve. The fuel solenoid of the tank will

open and stay open for 30 sec; during this time, fuel is supplied to the engine

directly from the fuel tank and is also filled the burette. After 30 seconds, the

fuel solenoid closes the fuel tank outlet, and now the fuel in the burette is

supplied to the engine.

When the fuel level crosses the high level optical sensor, the

sequence running in the computer records the time of this event. Likewise

when the fuel level crosses the low level optical sensor, the sequence running

in the computer records the time of this event and immediately the fuel

solenoid opens filling up the burette and cycle is repeated. Now, we know the

volume of the fuel between high level and low level optical sensors (20 cm3).

The starting time of fuel consumption, i.e. time when fuel crossed high level

sensor and the finish time of fuel consumption, i.e. time when fuel crossed

low level sensor gives an estimate of fuel flow rate i.e., 20 cm3/difference of

time in sec.

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5.3.4 Speed Sensor

A non contact PNP sensor (0-9999 rpm) is used to measure the

engine speed. A PNP sensor gives a pulse output for each revolution of the

crankshaft. The frequency of the pulses is converted into voltage output and

connected to the computer.

5.3.5 Load Cell (Torque Measurement)

Torque is measured using a load cell transducer (0-100 kg). The

transducer is strain gauge type. The output of load cell is connected to the

load cell transmitter. The output of load cell transmitter is connected to the

USB port through interface card.

5.3.6 Temperature Sensors

K-type thermocouples are located at appropriate places to measure

the following temperatures. The output of the temperature transmitters is

connected to data acquisition card.

Inlet water temperature in calorimeter

Outlet water temperature in calorimeter

Inlet exhaust gas temperature in colorimeter

Outlet exhaust gas temperature in colorimeter

Inlet water temperature to the engine cylinder

Outlet water temperature from the engine cylinder

Lube oil temperature

5.3.7 Pressure Sensor and Crank Angle Encoder

A Kistler piezoelectric transducer (water cooled type) is installed in

the cylinder head in order to measure the combustion pressure. Signals from

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pressure transducer are fed to charge amplifier. A high precision crank angle

encoder is used for delivering signals for TDC and crank angle. The signals

from charge amplifier and crank angle encoder are acquired using Kistler data

acquisition system (12 bit). In-cylinder pressure and top dead center signal are

acquired and stored on a high speed computer based digital data acquisition

system. There are filters present in the pressure signal. The data from 100

consecutive cycles are recorded. These are processed with specially

developed software to obtain the pressure crank angle data. A program has

been developed to obtain the average pressure crank angle data of 100 cycles.

Pressure versus crank angle data is stored in the computer and used

to calculate rate of heat release and then analyze the combustion

characteristics. The net heat release rate is the difference between the heat

released by combustion of fuel and the heat absorbed by cylinder wall. Using

the first law of thermodynamics, the net heat release rate is given by

Equation 5.1.

=1

+1

1 (5.1)

where is the crank angle and is the ratio of specific heats, Cp/Cv. The wall

heat transfer and blow by losses are not considered to find the heat released

due to combustion of fuel inside the cylinder. This helps to eliminate the

additional approximation in the analysis of heat release (Heywood 1988). The

ignition delay in a diesel engine is defined as the time between the start of

fuel injection and the start of combustion. The start of fuel injection is usually

taken as the time when the injector needle lifts off its seat. Since needle lift

sensor is not available, the timing at which fuel injection line pressure reaches

the injector nozzle opening pressure (210 bar) is taken as the start of injection.

Hence, the fuel pump and injector setting are kept identical for all fuels. The

start of combustion can be influenced by changes in fuel properties such as

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viscosity. The start of combustion is defined in terms of the change in slope of

the heat release rate that occurs at ignition. Hence the ignition delays for the

fuels are defined as an interval between 230 CA BTDC (standard injection

timing) and fuel ignition. The Total combustion duration is calculated based

on the duration between the start of combustion and 90% cumulative heat

release.

5.3.8 Emission Analyzer

Figure 5.14 Photographic view of smoke meter

Smoke meter as shown in Figure 5.14 is used to measure the

intensity of smoke present in the exhaust gas and the specification of the

smoke meter is given in Table 5.2. Gas analyzer as shown in Figure 5.15 is

used to measure the CO, CO2, HC, NOx and O2 present in exhaust gas. This

analyzer consists of Non-Dispersive Infrared Detector (NDIR) which detects

CO, CO2, NOx HC emission and Lambda sensor which senses the O2.

Specification of the gas analyzer is given in Table 5.3. The range and

accuracy of measurement are listed in Table 5.4.

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Table 5.2 Smoke meter specifications

Model AVL 437 Measuring range 0-100 opacity in %

0-99.99 absorption m-1

400….6000 min-1

0…150 CAccuracy and reproducibility ±1% Full scale reading Max smoke temperature at entrance 250 C

Table 5.3 Gas analyzer specifications

Type AVL DiGas 444 Measured quality Measuring range

CO 0… 10 % vol CO2 0… 20 % vol HC 0… 20000 ppm O2 0… 22 % vol

NOx 0… 5000 ppm

Figure 5.15 Photographic view of five gas analyzer

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Table 5.4 List of instruments for measuring various parameters and

the range, accuracy.

Sl.No Instruments Range Accuracy

1 Pressure pick up 0-110 bar ± 1 bar

2 Crank angle encoder ± 10

3 Exhaust gas Analyzer

NOx 0-5000 ppm ± 5 ppm

CO 0-10 % vol ± 0.01%

HC 0-20000 ppm ± 2 ppm

4 Smoke intensity 0-100 opacity in %

±2%

The percentage uncertainties of the various instruments are given in

the Table. A1.1.

5.4 EXPERIMENTAL PROCEDURE

5.4.1 Base Line Testing

The flow of air, the level of lubricating oil and the fuel level

are checked before starting the engine.

The engine is operated at the rated speed of 1500 rpm. The

load, defined in terms of brake power (BP), is changed in five

levels from no load (BP = 0 kW) to full load (BP = 3.5 kW).

The time taken for 20 cm3 of fuel consumption for every load

change is recorded.

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Under each load, by the exhaust gas analyzer, the CO, CO2,

HC, O2, NOx, and by smoke meter, the intensity of smoke and

the exhaust gas temperature are measured and recorded.

After the baseline testing, experiments are carried out to study the

combustion, performance and emission characteristics of the diesel engine

operating with Azadirachta indica seed oil and the test procedure is presented

in the following sections 5.4.2-5.4.5. For all the tests, the engine is started

with diesel fuel and allowed to stabilize for 45 minutes. After the engine is

warmed up, it is then switched to fuel blends. For each experiment, three

measurements are taken to average the data so as to determine the

repeatability of the measured data and have an estimate of measured accuracy.

At the end of test, the fuel is switched back to diesel and the engine is kept

running for a while before shutdown to flush out the fuel blends from the fuel

lines and injection system. By doing this, cold starting problems can be

avoided to some extent.

5.4.2 Combustion, Performance and Emission Characteristics of the

Diesel Engine Fuelled with Diesel and Neat NeO

The experiments are conducted at a constant speed of 1500 rpm

under variable load conditions to study the combustion, performance and

emission characteristics of the diesel engine operating on diesel (denoted as

D100) and NeO. The determination of specific gravity, calorific value, flash

and fire points, cloud and pour points and viscosity of diesel and NeO is

carried out, as per the ASTM standard, by using a hydrometer, a Bomb

calorimeter, Flash and Fire point apparatus, Cloud and Pour point apparatus

and a Redwood viscometer respectively. The important fuel properties of

diesel and NeO are shown in Table 6.1. The measured combustion,

performance and emission parameters are:

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Cylinder pressure variation with crank angle.

Rate of heat release variation with crank angle.

Ignition delay.

Combustion duration.

Equivalence ratio.

Exhaust gas temperature.

Brake thermal efficiency.

Brake specific energy consumption.

BSCO, BSHC, BSNOx and smoke intensity.

5.4.3 Performance and Emission Characteristics of the Diesel Engine

Fuelled with Neat NeO and its Blends with Alcohols

The NeO used is more viscous than diesel. To improve the oil

viscosity, four different alcohols are individually blended with neat NeO by

manual mixing at room temperature. Hence, experiments are conducted at a

constant speed of 1500 rpm under variable load conditions to study the

performance and emission parameters of the unmodified diesel engine

operating on NeO and its blends of 5 vol%, 10 vol%, 15 vol% and 20 vol%

with ethanol, 1-propanol, 1-butanol and 1-pentanol.

With naked eye observations, it is found that methanol did not mix

with NeO. When ethanol is mixed, there is complete mixing up to 10%

addition. When 1-propanol, 1-butanol and 1-pentanol is individually mixed,

there is complete mixing up to 20 % addition. For these experiments, no

cetane improving additives are used.

Two NeO-Ethanol (N-E) blended fuels are obtained by blending 5%

and 10% (by vol) of ethanol into NeO and are denoted as N-E5 and N-E10

83

respectively. Four NeO-propanol (N-P) blended fuels are obtained by

blending 5%, 10%, 15% and 20% (by vol) of 1-propanol into NeO and are

denoted as N-P5, N-P10, N-P15 and N-P20 respectively. Four NeO-butanol

(N-B) blended fuels are obtained by blending 5%, 10%, 15%, and 20% (by

vol) of 1-butanol into NeO and are denoted as N-B5, N-B10, N-B15 and N-

B20 respectively. Four NeO-pentanol (N-PT) blended fuels are obtained by

blending 5%, 10%, 15%, and 20% (by vol) of 1-pentanol into NeO and are

denoted as N-PT5, N-PT10, N-PT15 and N-PT20 respectively. The important

fuel properties of diesel, NeO, ethanol, 1-propanol, 1-butanol and 1-pentanol

are shown in Table 6.3.

The properties of the blended fuels are estimated with the following

formulas according to the volumetric concentration of each constituent

(Jianxin Wang et al 2009).

(1) Cetane number

=

(5.2)

where CNH is the equivalent cetane number of the blended fuel, while CNi is

the cetane number of each constituent.

(2) Oxygen content

=

(5.3)

Where CH is the oxygen content of the blended fuel, while i is the

measured density of each constituent and Ci is the oxygen content of each

constituent. The density of the blended fuel is calculated with the formula

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used in Equation (5.2). The lower calorific value is also calculated with the

formula in Equation (5.3).

The measured performance parameters are brake thermal efficiency,

brake specific energy consumption and the emission parameters are BSCO,

BSHC, BSNOx and smoke intensity. The performance and emission

characteristics are presented for BP = 1 kW and BP = 3.5 kW and the results

are discussed for lower engine loads (BP= 0 kW and 1 kW) and for higher

engine loads (BP = 2 kW, 3 kW and 3.5 kW).

5.4.4 Combustion, Performance and Emission Characteristics of the

Diesel Engine Fuelled by NOME and its Blends with Diesel

However, the resulting decrease in viscosity may not be low enough

to have any significant effect on the performance and emission characteristics

of the fuel and also to reach the same level of viscosity as diesel, neat NeO

has been transesterified to produce methyl ester of neem oil (NOME), called

biodiesel. As it is difficult to produce methyl ester from NeO using alkaline

catalyst (NaOH/KOH) because of its high FFA, preheating using acidic

catalyst has been done to reduce the FFA level in it. After pretreatment, the

process is continued with alkali-base catalyst to convert triglycerides to ester.

Using RSM, a series of experiments with three factors such as catalyst

concentration, reaction time and reaction temperature at two levels are carried

out in order to study the effects of those three factors in the alkaline base

catalyst transesterification reaction on the yield of biodiesel. The NOME is

then analyzed using standard biodiesel techniques like FTIR and NMR

(1H, 13C) spectroscopic methods.

Experiments are conducted at a constant speed of 1500 rpm under

variable load conditions to study the influence of NOME and its blends with

diesel namely 10%, 20%, 30%, 50% and 100% (B10, B20, B30, B50 and

85

NOME) on the combustion, performance and emission characteristics of the

diesel engine operating on. The properties of B10, B20, B30, B50 and B100

are determined and summarized in Table 6.4. The measured combustion,

performance and emission parameters are:

Cylinder pressure variation with crank angle.

Rate of heat release variation with crank angle.

Ignition delay.

Combustion duration.

Equivalence ratio.

Exhaust gas temperature.

Brake thermal efficiency.

Brake specific energy consumption.

BSCO, BSHC, BSNOx and smoke intensity.

5.4.5 Combustion, Performance and Emission Characteristics of the

Diesel Engine Fuelled by NOME and its Blends with DEE, ETH,

DMC and DGL

The major problem associated with the use of biodiesel, especially

that produced from NeO is its relatively higher viscosity, lower volatility and

low temperature flow properties than those of diesel. In order to provide

significant improvement in combustion, performance and exhaust emissions,

experiments are conducted at a constant speed of 1500 rpm under variable

load conditions to study the influence of NOME and its blends of 5 vol%, 10

vol%, 15 vol% and 20 vol% with DEE, ETH, DMC and DGL. The blended

fuels contain 5%, 10% and 15% by volume of DEE, and are identified as

BD5, BD10 and BD15, the blended fuels contain 5%, 10%, 15% and 20% by

86

volume of ETH, and are identified as BE5, BE10, BE15 and BE20, the

blended fuels contain 5%, 10%,15% and 20% by volume of DMC, and are

identified as BC5, BC10, BC15 and BC20 and the blended fuels contain 5%,

10% ,15% and 20% by volume of DGL, and are identified as BG5, BG10,

BG15 and BG20. The adiabatic flame temperatures for NOME, DEE, ETH,

DMC and DGL are calculated at an equivalence ratio of 1.0 and shown in

Table 6.5. The properties of DEE, ETH, DMC and DGL are shown in

Table 6.5 and the properties of blended fuels estimated according to the

volumetric concentration of each constituent using Equations (5.2) and (5.3)

are shown in Table 6.6-6.9. The measured combustion, performance and

emission parameters are:

Cylinder pressure variation with crank angle.

Rate of heat release variation with crank angle.

Ignition delay.

Combustion duration.

Exhaust gas temperature.

Brake thermal efficiency.

Brake specific energy consumption.

BSCO, BSHC, BSNOx and smoke intensity.