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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
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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
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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
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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
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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.
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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
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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
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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
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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).
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Figure 5.7 1H NMR spectra of NeO
Figure 5.8 Enlarged view of 1H NMR spectra of NeO
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Figure 5.9 1H NMR spectra of NOME
Figure 5.10 Enlarged view of 1H NMR spectra of NOME
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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.
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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
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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
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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
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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
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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
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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
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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.