15

CHAPTER 2

REVIEW OF LITERATURE

The chapter gives the details of many studies that have been done

at the Universities across the world involving vegetable oils as a primary

source of energy. Particularly, during the early 1980's, studies were

completed that tested the possibility of using unmodified vegetable oils

as a replacement for diesel fuel. Also the use of vegetable oils and blends

is detailed in many literatures.

The real measure of success when using vegetable oil as a diesel

fuel extender or replacement depends primarily on the performance of

vegetable oils in engines over a long period of time. Thus many

researchers have been involved in testing programs designed to evaluate

long term performance characteristics. Results of these studies indicated

that potential hazards such as stuck piston rings, carbon buildup on

injectors, fuel system failure, and lubricating oil contamination existed

when vegetable oils were used as alternate fuels. This effect diminishes,

as the blend of vegetable oil in diesel is decreased

2.1 VEGETABLE OIL CHEMISTRY

The vegetable oil can be easily produced from seeds by the use of

mechanical press. Seeds contain a semi drying oil (40-50%) extractable

mechanically and the series of processes involved are drying, grinding,

16

steaming, air cooling and finally oil extraction by hydraulic presses and

screening.

These are a mixture of organic composites ranging from simple

straight chain compounds to complex structure of proteins and fat

soluble vitamins. Some inorganic compounds of heavy metals are also

present. Most of the hydrocarbons present in the vegetable oils are not

simple aromats but they also belong to turpine class. They are usually

fatty esters of glycerol (triglycerides). Because of greater density, their

heat value is comparable to diesel. Heat value decreases with increasing

unsaturation as a result of fewer hydrogen atoms. The presence of

molecular oxygen raises the stoichiometric A/F ratio. The properties of

these oils depends very much on many factors like refining techniques,

the extent of refining, oil seed growing climate and therefore may

contribute to variations in test results [28].

Vegetable oils do not harm environment as they do not contain

sulphur and therefore problems associated with sulphurous acid

aerosols would be reduced. And also would take away more CO2 from

the atmosphere for its production than will be added to atmosphere.

2.2 VEGETABLE OILS AS ALTERNATE TO DIESEL

Several researchers [16, 74] have carried out experimental

investigations to improve the performance of engines fuelled by vegetable

oils.

17

The oils that are extensively studied include various oils such as

Palm oil, Jatropha oil ,Coconut oil, Cottonseed oil, Rubber seed oil,

Rapeseed oil, Neem oil, Peanut oil, linseed oil, rice bran oil, soyabean oil,

mustardoiletc[8,9,20,26,24,36,40,42,43,50,52,73,105,99,110,111,112,1

16,118,121] drastically affects the engine performance and emissions.

One of the disadvantages of using these oils in diesel engines is nozzle

deposits, for which vegetable oil gives better performance compared to

crude vegetable oil.

Gerhard Vellguth [11] has conducted tests on some vegetable oils

and reported that the Viscosities were significantly higher and densities

were marginally higher as compared to diesel and Vegetable oils have

lower heating values.

Both vegetable oils and alcohols such as Methanol, Ethanol are

biomass derived renewable sources, but vegetable oils have properties

more suitable to compression ignition engines compared to Alcohols [17,

25]. Some of the vegetable oils which are also being investigated as

alternate fuels are Palm oil methyl easter , Neem oil, Babussa oil, Linseed

oil, Cotton seed oil and Jatropha oil etc. They also produce aldehydes

and ketones in their exhaust emission, which create associated

environmental and health troubles.

K. Pramanik [27] tested on jatropha curcas oil and showed that the

specific fuel consumption and the exhaust gas temperature were reduced

due to decrease in viscosity of the vegetable oil. Acceptable thermal

18

efficiencies of the engine were obtained with blends containing up to 50%

volume of jatropha oil. From the properties and engine test results it has

been established that 40–50% of jatropha oil can be substituted for

diesel without any engine modification and preheating of the blends.

Mohd. Yousuf Ali [41] investigated mainly on the performance of

the engine using parameters; fuel consumption, brake specific

fuel consumption, brake thermal efficiency, mechanical

efficiency, exhaust gas temperature and smoke density. The

engine performance parameters were calculated for each of the

fuel CSO0, CSO10, CSO20, CSO30, CSO40, CSO50 and diesel,

without any modification of the engine.

Y. He [35] used the cottonseed oil as renewable energy source, the

results obtained showed that a mixing ratio of 30% cottonseed oil and

70% diesel oil was practically optimal in ensuring relatively high thermal

efficiency of engine, as well as homogeneity and stability of the oil

mixture.

GVNSR Ratnakara Rao [76] experimented on optimum

compression ratio on a single cylinder four stroke variable compression

ratio diesel engine. Tests were carried out at compression ratios of 13:2,

13:9, 14:8, 15:7, 16:9, 18:1 and 20:2. Results showed a significant

improved performance and emission characteristics at a compression

ratio 14:8. The compression ratios lesser than 14:8 and greater than

19

14:8 showed a drop in brake thermal efficiency, rise in fuel consumption

along with increased smoke densities.

Woschni .G [2] predicted the behavior of diesel engines with altered

operating conditions by means of cycle simulation, a knowledge of the

rate of heat release is necessary. On a medium-speed diesel engine,

experimental investigations were carried out to determine the

relationship between the heat release diagram and parameters such as

equivalence ratio, charge air pressure, charge air temperature, engine

speed, and injection timing. For a mathematical representation of the

results, the actual heat release diagrams are replaced by simplified

“Wiebe” heat release diagrams, which have the same beginning and

duration of combustion; the shape, however, is simplified and chosen so

that if they are used for cycle simulations, the calculated values of peak

pressure, power output, and fuel consumption are in agreement with the

measured data. Such a simplified Wiebe heat release diagram is

characterized by four parameters: the beginning and duration of

combustion, the Wiebe parameter m, and the equivalence ratio.

Empirical correlations are established whereby it is possible to predict

variations of these parameters with altered operating conditions. If, for

an engine under consideration, the heat release diagram and the rate of

injection are known from measurement of one particular operating

point, by means of these correlations it is possible to predict the heat

release diagram for any altered operating conditions.

20

Ilaria Mormino [97] demonstrated the growing consensus that,

there will not be a single alternative to fossil fuels, but rather different

fuels, fuel feedstocks, engine types and operating strategies. For

stationary diesel engines, straight vegetable oils are an interesting

alternative to fossil diesel, because of their potential for lower life cycle

greenhouse gas emissions. Using animal fats is also compelling, as it

does not imply the cultivation of oil-bearing seeds and related emissions,

not to mention the „food versus fuel‟ debate.

Ch .S. Naga Prasad [106] observed that 25% of neat Castor oil

mixed with 75% of diesel is the best suited blend for Diesel engine

without heating and without any engine modifications. It is concluded

that castor non-edible oil can be used as an alternate to diesel, which is

of low cost. This usage of neat bio-diesel has a great impact in reducing

the dependency of India on oil imports.

T.Ganapathy[109] demostrated a methodology for thermodynamic

model analysis of Jatropha biodiesel engine in combination with

Taguchi‟s optimization approach to determine the optimum engine

design and operating parameters. Using linear graph theory and Taguchi

method an L16 orthogonal array has been utilized to determine the

engine test trials layout. In order to maximize the performance of

Jatropha biodiesel engine the signal to noise ratio (SNR) related to

higher-the-better (HTB) quality characteristics has been used.

21

N.R. Banapurmath [113] tested on a single cylinder, four-stroke,

direct injection, water-cooled CI engine operated in single fuel mode

using Honge, Neem and Rice Bran oils. In dual fuel mode combinations

of Producer gas and three oils were used at different injection timings

and injection pressures. Dual fuel mode of operation resulted in poor

performance at all the loads when compared to single fuel mode at all

injection timings tested. However, the brake thermal efficiency is

improved marginally when the injection timing was advanced. Decreased

smoke, NOx emissions and increased CO emissions were observed in dual

fuel mode for all the fuel combinations compared to single fuel operation.

K. Kannan [120] performed an experimental study on a light duty

direct injection diesel engine at 150 bar, 200 bar and 250 bar injection

pressure to study its effect on performance and emission. The injection

pressure was changed by adjusting the fuel injector spring tension. The

performance and emission characteristics were presented graphically

and concluded that they were found better at the fuel injection pressure

200 bar for the light duty engine.

Several researchers [124, 125] have carried out experimental

investigations to improve the performance and emission of engines by an

artificial neural network. An artificial intelligence technique is developed

to successfully apply on automotive sector as well as many different

areas of technology aiming to overcome difficulties of the experiments,

minimize the cost, time and workforce waste. Diesel fuel, biodiesel, B20

22

and bio ethanol–diesel fuel having different percentages (5%, 10%, and

15%) and biodiesel were mixed together, to use in developed artificial

neural network

2.3 NEAT VEGETABLE OILS

G.Lakshmi Narayana Rao [133] investigated on Biodiesel, an

alternative fuel can be used in diesel engines as neat or blended with

diesel. The physiochemical properties of fuel are important in design of

fuel system for compression ignition engines run on diesel, biodiesel or

biodiesel blends. Biodiesel (B100) standards specify the limit values of

these properties for blending with diesel. However, there are variations in

the properties of biodiesel. The properties of biodiesel vary depending on

the feedstock, vegetable oil processing, production methods and degree of

purification. The objective of this study is to estimate the mathematical

relationships between viscosity, density, heating values and flash point

among various biodiesel samples. There is a high regression between

various properties of biodiesel and the relationships between them are

observed to be considerably regular.

Matthew Hayden [32] concluded that in a CIPP system versus that

of a neat system shows increases in flexural and tensile modulus,

decreases in tensile and flexural strength, and decreases in the tensile

elongation.

Nestor U. Soriano [33] concluded that the presence of carbon-

carbon double bonds along the hydrocarbon chains is necessary to make

23

ozonized vegetable oil an effective pour point depressant for fatty acid

methyl esters (FAME). Differential scanning calorimetry and polarized

light microscopy revealed that ozonized vegetable oil affects both

nucleation and crystal growth of FAME and biodiesel

Murugu Mohan Kumar Kandasamy [93] showed that the thermal

efficiency is slightly less and the specific fuel consumption is slightly

higher with Ester of sunflower oil when compared with Diesel. This is

due to the lower calorific value of the Ester of sunflower oil

A. A. Refaat [82] reviewed that it was clear that the produced

biodiesel fuel, whether from neat vegetable oil or waste vegetable oil, was

within the recommended standards of biodiesel fuel

G. El Diwani; [83] showed that the oxygen content of biodiesel

samples treated with ozone increased weight % and resulted in more

extensive chemical reaction, promoted combustion characteristics and

less carbon residue was produced. Gas chromatography appeared more

suitable to address the problem of determining/verifying biodiesel methyl

ester and showed that methyl ester content was impurity free

Guo, Y., Leung [22] demonstrated that using the biodiesel

produced could reduce smoke and HC emissions significantly while the

NOx emission changed slightly. There is an unnoticeable drop in the

maximum engine power output even at 100% biodiesel.

Meda Chandra Sekhar [136] reported that petroleum product

resources are limited and their consumption is increasing very fast with

24

globalization and high technology development since last decade. Since

the prices of these products are on the rise at any given time, there is a

need to search for an alternate source, which would fuel our vehicles

without any major vehicle modification

Jon H. Van Gerpen [68] reviewed that when the fuel meets this

standard, it has been shown to provide improved lubricity, higher cetane

number, lower emissions of particulate, carbon monoxide, unburned

hydrocarbons but higher level of oxides of nitrogen. While the current

availability of vegetable oil limits the extent to which biodiesel can

displace petroleum to a few percent, new oil crops could allow biodiesel

to make a major contribution in the future.

William A. Newman [54] demonstrated the effect of Newman Zone

in reducing chlorinated solvent concentrations in groundwater by both

rapidly stimulating initial microbial activity and supporting long-term

reductive dechlorination with a slow-release electron donor.

A. Abuhabaya [137] resulted that it has been established that

biodiesel of WVO can be substituted for diesel without any engine

modification and preheating of the fuels. Sustainability issues present an

obstacle for general use so only small fleet operators may take advantage

of the alternative fuel.

Dilip R. Pangavhane [55] showed that the petroleum diesel, the

biodiesel operates the combustion ignition engines. Though the various

straight vegetable oils (SVO), edible and non-edible oils can be used for

25

manufacturing biodiesel, out of which karanja oil is one of the best oil

suitable for production of biodiesel. The multiple engine performance

tests were conducted from the obtained biodiesel on a four-stroke, two-

cylinder water-cooled diesel engine producing 10HP, 1500 RPM with

10KV Dynamometer

S S Pandian [56] concluded that performance of vegetable oil esters

such as Jatropha, Mahua and Neem oil esters were in good agreement

with diesel performance. Thus the developed model was highly

compatible for simulation work with bio diesel as a suitable alternative

fuel instead of diesel

Despite the lower SATS and higher MONOS content of canola oil

and the higher POLYS content of corn oil, RBO produced similar

reductions in serum total cholesterol (TC) (225%) and low density

lipoprotein cholesterol (LDL-C) (230%). In addition, as compared to the

baseline diet, the reduction in serum

TC and LDL-C cholesterol with RBO was not accompanied by reductions

in high density lipoprotein cholesterol (HDL-C) which occurred with the

other two dietary oils. Using predictive equations developed from data

gathered from several studies with non-human primates, we noted that

the observed serum TC and LDL-C lowering capabilities of the RBO diet

were in excess of those predicted based on the fatty acid composition of

RBO [18]

26

I L Hosier [91] showed that vegetable oils offer the added advantage

of being renewable although many types are available with very different

properties. In order to select a suitable vegetable oil for high voltage

applications, a standardised ageing and testing regime is required

Emil Akbar [92] conducted tests on fatty acid and triacylglycerol

(TAGs) composition of the extracted lipid was revealed using the gas

chromatography (GC) and high pressure liquid chromatography (HPLC)

method. Both oleic acid (44.7%) and linoleic acid (32.8%) were detected

as the dominant fatty acids while palmitic acid and stearic acid were the

saturated fatty acids found in the Jatropha oil.

Ulf Schuchardta [15] showed that the transesterification of

vegetable oils with methanol as well as the main uses of the fatty acid

methyl esters are reviewed. The general aspects of this process and the

applicability of different types of catalysts (acids, alkaline metal

hydroxides, alkoxides and carbonates, enzymes and non-ionic bases,

such as amines, amidines, guanidines and triamino(imino)phosphoranes)

are described

Kunchana Bunyakiat [14] found that the best condition to produce

methyl esters from coconut oil and palm kernel oil was at a reaction

temperature of 350 °C, molar ratio of methanol-to-vegetable oil of 42, and

space time 400 s. The % methyl ester conversions were 95 and 96 wt %

for coconut oil and palm kernel oil, respectively

27

A.V. Krishna Reddy [141] conducted experiments on 5.2 BHP

single cylinder four stroke water-cooled variable compression diesel

engine. Methyl ester of cottonseed oil is blended with the commercially

available Xtramile diesel. Cottonseed oil methyl ester (CSOME) is blended

in four different compositions varying from 10% to 40% in steps of 10

vol%. Using these four blends and Xtramile diesel brake thermal

efficiency (BTE) and brake specific fuel consumption (BSFC) are

determined at 17.5 compression ratio.

2.4 PROBLEMS ASSOCIATED WITH THE USE OF CRUDE

VEGETABLE OIL IN CONVENTIONAL ENGINE

Though with minor modifications these vegetable oils can be used

in CI engine, but there are certain problems associated with their high

viscosity and high carbon residue. The high viscosity of the oil causes

problems in pumping and atomization, leading to poor performance of

the engine.

Vegetable oils lack the low flammability needed for spark ignition

engines, while these are similar to diesel in cetane rating and heat value.

Some of the problems caused by these oils include slightly lowered

power, poor spray, distorted combustion, wear problem, high smoke

during combustion plus filter plugging, excessive deposits. Noise, cold

start and odour are the other problems associated with them. Due to

higher molecular weights, vegetable oils have low volatility and because

of their unsaturation, these are inherently more reactive than diesel

28

fuels. As a result, they are much more susceptible to oxidation and

thermal polymerization reactions as reported in the literature.

After a thorough review of the literature it is observed that there

are operational, durability problems with the vegetable oil engines.

Starting ability, ignition and combustion and performance come under

operational problems where as the problems like deposit formation,

carbonization of injector tip, ring sticking and lubricating oil dilution

come under durability problems [13, 23, 127]. Durability problems

appear to be a very strong function of the engine type, with direct

injection engines being more susceptible than the indirect injection

engines.

Many researchers [70] have observed that the crude vegetable oils,

when used for long hours, choke the fuel filter because of high viscosity

and insolubles in crude oil. Viscosity of vegetable oils exerts a strong

influence on the fuel spray pattern. High viscosity causes poor

atomization, large droplets and high spray jet penetration. As a result,

the mixing of fuel and air mixture may be improper and affects burning.

This may further lead to poor combustion, accompanied by loss of power

and economy. In small engines, the fuel spray may impinge upon the

cylinder walls, washing away the lubricating oil film and causing

dilution, of the crank case oil. Most of the oils have kinematic viscosity

in the range of 30 to 50 centistokes where as for diesel oil is 1.9 to 4.1

centi stokes.

29

2.5 VEGETABLE OIL FUEL BLENDS

Vegetable oils can also be used as a diesel fuel alternative by

supplementing with diesel oil. Vegetable oils offer the advantage of freely

mixing with diesel oil and can be used as supplement with diesel oil in

existing engines without any modifications. Vegetable oils in varying

proportions in the fuel blend were tried by a number of investigators [1,

90,114, 117, 129]. Significant reductions in viscosity and improved

performance were reported with blending vegetable oils and diesel oil.

The performance was comparable to that of diesel oil.

Recip Altin [19] conducted short and long term tests using diesel

fuel; blend of 30%cottonseed oil and 70% diesel fuel(by volume);blend of

50% cottonseed oil and 50% diesel fuel; blend of 65%cottonseed oil and

35% diesel fuel; the short term results were more desirable than the long

term results. He also suggested that the fuel systems should be

optimized for vegetable oil operation, fuel characteristics of vegetable oils

should be improved.

A.S. Ramadhas [29] reviewed the use of vegetable oils as I.C.

Engine fuels. He Conducted trials on cottonseed oil blend with diesel.

They compared the engine performance and emission characteristics and

reported that all the oils provided almost similar characteristics.

D Sharma [37] reported that the properties of Neem-diesel blend

are comparable with those of pure diesel. Neem-diesel blends produced

lower exhaust emissions. There is significant effect of injection pressure

30

on engine performance. For both pure diesel and Neem-diesel blend 160

kgf/cm2 is the optimum injection pressure, as highest BTE and lowest

BSFC was observed over the entire load range at this injection pressure.

C.D. Rakopoulos [48] conducted a series of experiments at 2000

rpm and at medium and high load. BSFC and brake thermal efficiency

were computed from the measured fuel volumetric flow rate and calorific

values. The engine performance showed that brake thermal efficiency of

blends was similar with diesel oil and BSFC showed higher values for the

high load and minimum of it at10/90 blend for the medium load.

Georgios Fontaras [57] experimented with vegetable oils blended

with diesel fuel, which are recognised as biofuels by the European

legislation and their application is an interesting option for increasing

the market share of biofuels. The results from a detailed study conducted

on a Euro 3 compliant diesel passenger car and a high injection pressure

test bench engine using 10% Cottonseed oil- 90% Diesel blends as fuel

were showed.

N.R.Banapurmath [95] successfully tested Neem oil in Diesel

engine and noticed that there is no much modification needed for diesel

engine. And performance and emission rates showed consistency with

that of diesel fuel. In the present work the fuel considered for

investigation is Neem oil. The fuel blends were prepared using an

emulsifier and the experiments were conducted on a twin cylinder diesel

engine.

31

Nilaj N. Deshmukh [107] reported that the use of food grain based

biodiesel may lead to increase in food prices. Therefore there is a need for

finding availability and feasibility of non-food based biodiesel. In this

work, evaluation of combination of food grain and non food grain

biodiesel has been made by using these two different sources of biodiesel

in various blends such as B40 and B60. These blends are tested for

variety of physical and chemical characteristics of fuel.

P.V. Krishna Murthy [108] demonstrated crude-Jatropha oil, a

non-edible vegetable oil which shows a greater potential for replacing

Conventional diesel fuel quite effectively, as its properties are compatible

to that of diesel fuel. But low volatility and high viscosity of jatropha oil

call for low heat rejection (LHR) in diesel engines.

2.6 VEGETABLE OIL HEATING

Vegetable oil heating is one of the techniques to reduce its

viscosity. The fuel viscosity at the fuel injector is important for good

atomization and combustion. With a high fuel viscosity, fuel spray can

impinge upon the walls of the combustion chamber resulting in delayed

combustion and burning. If heated to very high temperatures, low

viscosity of the fuel can result in poor fuel droplet penetration and poor

combustion.

D.L.Hilden [6] used an electric air heater or an electric air heater

together with a steam heater for the mixture preparation. Organic

emissions of UBF and aldehydes and the effects of adding water to

32

methanol were studied. UBF and aldehyde emissions for methanol were

found many times greater than with gasoline, but special mixture

preparation methods would improve the situation.

Norman.D.Brinkman [7] conducted an experiment on Waukesha

removable dome head single-cylinder engine operated with methanol.

Manifold fuel injection along with electric air heating and steam heating

of the moisture was used. Performance, NOx and UBF emissions were

studied at a constant engine speed and airflow, varying the CR from 8 to

18. With MBT spark, trace knock was noticed at a CR of 18. Efficiency

and power increased by about 16%, as the CR was changed from 8 to 18.

S. Bari [21] focused on finding out the effects of preheating of fuel

on the injection system utilising a modified method of friction test, which

involves injecting fuel outside the combustion chamber during motoring.

Results show that preheating of CPO lowered CPO‟s viscosity and

provided smooth fuel flow, but did not affect the injection system, even

heating up to 1000C. Nevertheless, heating up to such a high

temperature offered no benefits in terms of engine performance but was

found that a lower maximum heat release rate was obtained and a longer

combustion period.

Felycia Edi Soetaredjo [77] reported that the pretreatment heating

on the Neem seed particles and storage caused the oil quality reduced,

therefore room temperature was found to be the recommended

temperature for the Neem oil extraction using mechanical process.

33

Murat Karabektas[79] reported that preheating COME up to 900C

leads to favourable effects on the BTE and CO emissions but causes

higher NOx emissions. Moreover, the brake power increases slightly with

the preheating temperature up to 900C. When the COME is preheated to

1200C, a considerable decrease in the brake power was observed due to

the excessive fuel leakage caused by decreased fuel viscosity. The results

suggest that COME preheated up to 900C can be used as a substitute for

diesel fuel without any significant modification in expense of increased

NOx emissions.

M. Nematullah Nasim [122] showed that preheating of the neat

jatropha oil is done from 30oC to 100oC. The performance of the engine

was studied for a speed range between 1500 to 4000 rpm, with the

engine set at full throttle opening and hence the engine was operated

under full load conditions. The parameters considered for comparing the

performance of neat jatropha oil with that of diesel fuel operation, were

brake specific fuel consumption, thermal efficiency, brake power, NOX

emission of the engine.

2.7 ESTERIFICATION PROCESS

By the process of esterification the high viscosity of vegetable oils

can be brought down to acceptable limits. There are three routes to ester

production from oils and fats. The first route is Base catalyzed

transesterification of oil with alcohol; the second route is Direct acid

catalyzed esterification of oil with methanol. The third route is

34

Conversion of the oil to fatty acids and then to alkyl esters with acid

catalysts.

The first method is preferred because it is economical. The

conversion of vegetable oil (Triglyceride Esters) to methyl esters through

transesterification process reduces the molecular weight to one-third,

reduces the viscosity by a factor 8 and increase the volatility. The

vegetable oil is mixed with alcohol and NaOH as catalyst. The mixture is

heated and maintained at 650C for one hour, while heating the solution

is stirred continuously with stirrer. Two distinct layers are formed, the

lower layer is glycerin and upper layer is ester. The upper layer is

separated and moisture from the ester is removed by using calcium

chloride. It is observed that 90% of ester is obtained from vegetable oil.

The engine performance shows an improvement when esterified

fuels are used instead of base vegetable oils [10, 12, 31, 44, 58, 60, 61,

78, 96, 100, 115, 123, 126]. This improvement in performance can be

attributed to good efficiency, environment friendly and a significant

reduction in the viscosity.

Naveen Kumar [30] adopted transesterification to develop methyl

ester of palm oil that approximates the properties and performance of

hydrocarbon-based diesel fuel. Various properties of the methyl ester of

palm oil were evaluated and compared in relation with that of neat diesel.

The prepared methyl ester of palm oil, blended in different

concentrations with neat diesel was then subjected to performance and

35

emission tests in order to evaluate its suitability in diesel engine. The

data thus generated was compared with base line data generated from

neat diesel.

Among the different possible sources, bio-diesel fuels derived from

triglycerides present a promising alternative to substitute diesel fuels.

Fatty acid methyl and ethyl esters, known as biodiesel, derived from

triglycerides by transesterification with methanol or ethanol have

received the most attention. The main advantages of using biodiesel are

its renewability, its biodegradability and it does not contribute to a rise in

the level of carbon dioxide in the atmosphere and consequently to the

greenhouse effect [38]

C.Muraleedharan [45] used the biodiesel production method which

consists of acid-catalyzed pretreatment followed by an alkaline-catalyzed

transesterification. The important properties of methyl esters of rubber

seed oil were compared with other esters and diesel, and reported that

the lower blends of biodiesel increase the brake thermal efficiency and

reduce the fuel consumption. The exhaust gas emissions are also

reduced with increase in biodiesel concentration. So the use of biodiesel

in CI engines is a vaiable alternative to diesel.

CHEN He [63] used solid acids which were prepared by mounting

H2SO4 on TiO2 · nH2O and Zr(OH)4, respectively, followed by calcining at

8230K. TiO2- SO4 and ZrO2-SO4 showed high activity for the

transesterification. The yield of methyl esters was over 90% under the

36

conditions of 230°C, methanol/oil mole ratio of 12:1, reaction time 8h

and catalyst amount (catalyst/oil) of 200(w).The solid acid catalysts

showed more better adaptability than solid base catalysts when the oil

has high acidity.

Properties of different blends of biodiesel are very close to that of

diesel and B20 gives good results but it is not advisable to use B100 in

CI engines unless its properties are comparable with diesel fuel. [72]

The important properties of the biodiesel oil such as flashpoint,

viscosity, calorific value, density are comparable with that of diesel. The

viscosity of biodiesel oil is nearer to that of diesel and the calorific value

is about 16% less than that of diesel [101]

2.8 VEGETABLE OIL SUITABILITY

T. MohanRaj [132] noted that Vegetable oil has become more

attractive recently because of its environmental benefits and better

quality exhaust emission. A well-known transesterification process made

biodiesel, pungam seed oil was selected for biodiesel production. Pungam

seed oil is non-edible oil, thus, food versus fuel conflict will not arise if

this is used for biodiesel production.

Saravanan Subramani [86] Investigated high FFA CRBO which was

subjected to esterification and transesterification processes and the

crude rice bran oil methyl ester (CRBME) obtained was tested in a

compression ignition (CI) engine to determine its ability to replace

petroleum diesel and lead to a reduction in pollutants. A 4.4 kW, four-

37

stroke, direct-injection, air-cooled, stationary diesel engine was used in

this investigation. CRBME has less emission of unburned hydrocarbon

(UBHC), nitrogen oxides (NOX) and smoke density with a marginal

increase in carbon monoxide (CO) emissions, when compared with diesel

A. Rehman [88] analyzed performance for esters of karanja oil,

blends of karanja oil, and the diesel oil as baseline at varying loads

performed at governor controlled speed. The variations in the injection

parameters were analyzed to observe its influence on the engine

performance with different fuels. Experimental results showed that diesel

engine gives poor performance at lower Injection Pressure than esterified

karanja oil and its blends with diesel.

G. Nagarajan [84] studied Crude rice bran oil (CRBO) with high

free fatty acid (FFA) content which is not suitable for eating purposes,

however, it can be used as a fuel to partially replace or fully replace No.2

diesel. The main objective of the present work was to analyse the effect of

FFA content of CRBO on the combustion properties such as viscosity,

calorific value, volatility and aniline point. CRBO with different FFAs

were collected and mixed with No.2 diesel to prepare CRBO-diesel

blends. It was observed that the viscosity of the blends increased with

increase in FFA while the calorific value decreased. Significant variations

were observed in the distillation curve for the CRBO blends with different

FFA. Aniline point of the blends was 10–15% lower than that of diesel

and it is indirectly proportional to the FFA of CRBO in the blend.

38

G. Lakshmi Narayana Rao [135] tested CRBO samples of different

FFAs in blended form to analyze the effects of high FFA with respect to

engine performance and emission characteristics. With CRBO blends

unburned hydrocarbon emissions were decreased significantly at all

loads as a result of enhanced thermal oxidation inside the combustion

chamber. The nitrogen oxides (NOX) emissions were reduced at lower

loads and particulate emission reduced at higher loads. A marginal

increase in carbon monoxide (CO) emission was noticed at all loads

relative to diesel.

The blends of varying proportions of the jatropha and karanja with

diesel were prepared, analysed, and compared with diesel oil. The engine

performance and emission characteristics were evaluated in a single

cylinder CI engine and a comparison was made to suggest the better

option among the biodiesel under study [89]

J.G. Suryawanshi [53] observed that penetration length is more

and spray cone angle is less as compared to diesel for neat honge oil at

different injection pressure. This is because of influence of higher density

and viscosity of vegetable oil.

Vegetable oils pose some problems when subjected to prolonged

usage in compression ignition engines because of their high viscosity and

low volatility. The common problems are poor atomization, carbon

deposits, ring sticking, fuel pump failure, etc. Converting the high

39

viscosity vegetable oil into its blends or esters can minimize these

problems [46]

Samir J. Deshmukh [87] analyzed by running the engine in liquid

fuel mode operation and in dual fuel mode operation at different load

conditions with respect to maximum diesel savings in the dual fuel mode

operation. It was observed that specific energy consumption in the dual

fuel mode of operation is found to be in the higher side at all load

conditions

Ahmed Saad Gad [138] showed that the solubility of carotenoids

increased with blinding, pasteurization and homogenization. The partial

substitution of milk fat was the most suitable milk fat phase as a healthy

benifits. Broccoli showed the highest carotenoid content and also

recorded the highest antioxidant activity

Jehad A. A. Yamin [66] showed the advantages of VSE over fixed

stroke engines. This study showed that the variable stroke technique

proved a good way to curb the diesel exhaust emissions and hence

helped making these engines more environmentally friendly

2.9 VEGETABLE OIL FEASIBILITY, ADVANTAGES AND

DISADVANTAGES

The oxidative stability showed COME with acceptable stability.

COME exhibited friendly environmental benefits and acceptable stability,

demonstrating its feasibility as an alternative fuel [85].

40

Sumiani Yusoff [67] show that fertilizer production is the most

polluting process in the system followed by transportation and the boiler

emissions at a tie. The most significant impacts from the system are

respiratory inorganics and depletion of fossil fuels, of which the boiler

emission is the main responsible for the prior and fertilizer production

and transportation are responsible for the latter.

Cetane number is an important parameter in evaluating the

quality of biodiesel fuel. Its determination is usually arduous and

expensive, and the results obtained are not always accurate due to

experimental error. This work is aimed at developing a relationship

between the fatty acid methyl ester (FAME) composition and the cetane

number (CN) [69]

The use of WVO as a fuel source would require more initial

modification of equipment, which would be especially difficult with the

majority of the existing diesel vehicles given the lack of WVO conversions

for off-road vehicles such as lawnmowers and tractors. Additionally, once

the vehicles are converted to run on WVO they will always remain

committed to it as a fuel source [134]

Arjun B. Chhetri [81] showed that biodiesel was characterized by

its physical and fuel properties including density, viscosity, acid value,

flash point, cloud point, pour point, cetane index, water and sediment

content, total and free glycerin content, diglycerides and monoglycerides,

phosphorus content and sulfur content according to ASTM standards

41

G Amba Prasad Rao [47] investigated on direct injection (DI) and

indirect injection (IDI) type engines at recommended injection pressure of

respective engines with methyl esters of Jatropha oil. Supercharging was

also done on DI engine in order to obtain the performance close to the

engine performance with diesel-fuel operation. Both engines were

evaluated in terms of parameters such as brake specific fuel

consumption and smoke density

R.Murali Manohar [139] showed a new method has been employed

to produce Bio-Diesel in a homely basis. The production of the Bio-Diesel

is done by using Bio-Diesel processor. It requires the used vegetable oil,

methanol and the lye with the accurate proportionate. Generally,

emissions of regulated compounds changed linearly with the blend level

Christianne E. C. Rodrigues [65] reviewed patents indicating

various advantages of a purification process based on the selective

extraction of free fatty acids using short chain alcohols. Its technical

feasibility is due to the differences in solubility of free fatty acids and

neutral oil in the proposed solvents. This alternative technique does not

generate waste products and can preserve nutraceutical compounds in

the refined oil

B.Radha madhavi [140] showed that healthy natural sunflower oil

is produced from oil type sunflower seeds.It is the non-volatile oil

expressed from sunflower (Helianthus annus) seeds of asteraceae family.

The sunflower oil is interesting by its content in linoleic acid. Sunflower

42

oil is light in taste and appearance and supplies more Vitamin E than

any other vegetable oil

Emmanuel O. Aluyor [94] stated that vegetable oils have

traditionally been applied in food uses, but recent trends suggest their

economic usefulness as industrial fluids. Increasing crude oil prices and

emphasis on the development of renewable, environmentally friendly

industrial fluids have brought vegetable oils to a place of prominence.

Biodegradability provides an indication of the persistence of any

particular substance in the environment and is the yardstick for

assessing the eco friendliness of substances. The superior biodegradation

of vegetable oils in comparison with mineral based oils has been

demonstrated severally, leaving scientists with the lone challenge of

finding economic and safe means to improve their working efficiency in

terms of their poor oxidative stability and high pour points.

2.10 EMISSIONS AND THEIR CHARACTERSTICS

2.10.1 Carbon monoxide (CO)

Carbon monoxide (CO) is a colourless, odorless, flammable and

highly poisonous gas which is less dense than air. Inhalation of carbon

monoxide can be fatal to humans since a small concentration as little as

0.1 % will cause toxication in the blood due to its high affinity to oxygen

carrying hemoglobin‟s. Apart from that, carbon monoxide also helps in

the formation of greenhouse gases and global warming by encouraging

the formation of NOX.

43

Carbon monoxide forms in internal combustion engines as result

of incomplete combustion when a carbon based fuel undergoes

combustion with insufficient air. The carbon fuel is not oxidized

completely to form carbon dioxide and water. This effect lies obvious in

cold weathers or when an engine is first started since more fuel is

needed.

Carbon monoxide emission from internal combustion engines

depend primarily on the fuel/air equivalence ratio (h).Spark ignition

gasoline engines which normally run on a stoichiometric mixture at

normal loads and fuel-rich mixtures as full load shows significant CO

emissions. On the other hand, diesel engines which run on a lean

mixture only emit a very small amount of CO which can be ignored.

Ferguson researched that additional CO may be produced in lean-

running engines through the flame-fuel interaction with cylinder walls,

oil films and deposits. Direct-injection diesel engines also emit more CO

than indirect-injection engines. However, the CO gas emission increases

with increasing engine power output for both engines.

CO formed from hydrocarbon radicals can be oxidized to form

carbon dioxide in an oxidation reaction in an equilibrium condition.

CO +OH= CO2 + H

The emission of CO is a kinetically-controlled reaction since

the measured emission level is higher that equilibrium condition for the

exhaust. Three –body radical recombination reactions such as.

44

H + H + M = H2 + M

H + OH + M = H2O + M

H + O2 + M = HO2 +M

Reduction of carbon monoxide in internal combustion can be achieved by

improving the efficiency of combustion process or utilization of oxidation

catalysts to oxidize carbon monoxide to carbon dioxide.

2.10.2 Hydrocarbon (HC)

Hydrocarbon (HC) is used to measure the level of formation of

unburnt hydrocarbons caused by incomplete combustion in the engine.

The hydrocarbons emitted may be inert such as methane gas or reactive

to the environment by playing a major role in the formation of smog. The

fuels with a greater concentration of aromatics and olefins compounds

will result in a higher percentage of reactive hydrocarbons.

In diesel engines hydrocarbons emission can be significant under

two normal operating conditions due to the complex nature of fuel-air

and burned-unburned gas mixing in the combustion chamber. Firstly, a

mixture of fuel leaner than the lean combustion limit in the chamber

during the ignition delay period will cause incomplete combustion and

hence formation of Unburnt hydrocarbons. The locally over lean mixture

of fuel will not auto ignite or support a propagating flame, causing a slow

reaction to develop.

On the other hand, under mixing of fuel which occurs when the

fuel mixture is too rich to ignite or support a flame causes hydrocarbon

45

formation during the combustion cycle. The injector sac volume provides

an important contribution to the hydrocarbon emission in the direct-

injection engines. The diesel fuel left as the tip of the injector enters the

cylinder at low velocity and does not have enough time to achieve a

standard mixture with air

2.10.3 Oxides of Nitrogen (NOX)

Nitrogen oxide consist primarily of nitric oxide (NO) a nitrogen

dioxide (NO2) as a product of oxidation of atmospheric nitrogen in the

combustion chamber. Diesel fuel contains a significant amount of

nitrogen compounds and acts as an additional source of NO. Formations

of nitric oxides from molecular nitrogen are described by the following

equations.

O + N2 NO = N

N + O2 NO =O

N + OH NO +H

Nitric oxides (NO) formed in the combustion chamber can be

rapidly oxidized to form NO2 through the following reaction;

N0 +H20 NO2 +OH

At the same time, NO2 will be subsequently converted back to NO

via;

NO2 + O NO+O2

A considerable amount of NO2 is found in diesel engines especially

during light loads or engine idling times. At lower temperatures, the

46

transformation of NO2 back to NO in reaction is quenched by the cooler

regions of the chamber and the ratio of NO2 to NO can go as high as

30%.

The maximum amount of NO2 is emitted in a diesel engine at low

engine speed and minimum loads. This can be damaging to the

atmosphere as NO2 formed will contribute to formation of ground-level

ozone or smugness and reacts in the air to form corrosive nitric acid.

At the same engine speed, the amount of NOX produced increases

with engine load for a direct-injection engine and the maximum amount

occurs when the fuel mixture is slightly lean. With higher loads, the peak

pressures of the cylinder and temperature distribution are higher and

coupled with enhanced mixing of the diesel fuel, NOX levels are

increased. As a rule of thumb, the emission of NO are roughly

proportional to the mass of fuel injected.

Selective catalytic reduction (SCR) can be used to convert NOX

emitted to from oxygen and nitrogen through the use of reducing agents

such as ammonia or urea. It is combined with an oxidation catalyst to

oxidize any traces of ammonia which may escape the system into the

atmosphere.

2.10.4 Carbon Dioxide (CO2)

Carbon dioxide emission in diesel engines are products of direct

combustions or by-product of oxidizing other unwanted emission gases

with the aid of catalysts. Although diesel engines generally produce low

47

amounts of CO2 compared to other emission gases, the emission of

carbon dioxide must be regulated and controlled to reduce negative

impacts on the environment such as accumulation of greenhouse gases

and global warming.

2.10.5 Smoke Density

The fuel injection pressure has a strong influence on the smoke

density under all operating conditions. The variation of smoke density

with the brake power for different fuel injection pressures. It is be

observed that, the smoke density is increased with an increase in the fuel

injection pressure in both the cases i.e. with diesel and blends.

Exhaust emissions as they are just the by-products of combustion

of a fuel. For every 1kg of fuel burnt, there is about 1.1kg of water (as

vapour/steam) and 3.2kg of carbon dioxide produced. Unfortunately we

don't have 100% combustion and so there is also a small amount of

products of incomplete combustion and these are carbon monoxide

denoted CO , hydrocarbons (vaporised fuel) and soot or smoke (actually

hydrocarbons in a different form). In addition, the high temperatures

that occur in the combustion chamber promote an unwanted reaction

between nitrogen and oxygen from the air. This result in various oxides

of nitrogen, commonly called NOX.

There are also several minor contributors to exhaust emissions

which are burnt crankcase oil and sulphur from the fuel. Both these

components will show up mostly as particulates. Oil consumption is

48

obviously a function of engine design and amount of wear but sulphur

dioxide is formed from the sulphur in the fuel.

N.D.Brinkman [3] studied NOX and UBF emissions at a constant

engine speed and airflow, varying the CR from 8 to 18. With MBT spark,

trace knock was noticed at a CR of 18. Efficiency and power increased by

about 16%, as the CR was changed from 8 to 18. NOX emissions are 15 –

200% greater at CR=8, depending on the equivalence ratio

CO emissions are lower in the fuel rich range, but higher by 50%

in the fuel lean range for methanol [4]

W.J.Most [5] reported that CLR engine operated with methanol and

isooctane, with carburetion improves specific energy consumption with

methanol. UBF emissions were no more severe with isooctane and

operation with higher compression ratios is possible with water addition

which results in improved energy economy, with no NOX penalty.

Thet Mya [39] Studied the fuel properties, the diesel combustion

and the exhaust emissions of palm kernel oil methyl ester (PKME) and a

blend of 20% PKME with 80% JIS No.2 gas oil (PK-B20) and reported

that the brake thermal efficiency of PKME was the same as the other test

fuels, the ignition ability of PKME was better than that of the gas oil and

the exhaust emissions (CO, HC, NOX and smoke) from PKME were almost

the same as those of CME and lower than those of the gas oil.

Specifically, at 100% load condition, about 47% reductions in smoke

emission was found in PKME compare to that of the gas oil.

49

The Biodiesel is an alternative diesel fuel which has many advantages

such as it can supply new energy source, it is renewable fuel and can

reduce net CO2 cycle, It helps reduce exhaust gas emission to meet the

future legislation due to oxygen content and high cetane number and It

also decreases impact to the environment due to high biodegradablity.

[59]

The R2 (R: the coefficient of determination) values are 0.99994, 1, 1

and 0.99998 for the engine torque, specific fuel consumption, CO and

HC emissions, respectively if the engine uses waste cooking oil. [62]

Dessy Y. Siswanto [75] demonstrated catalytic cracking of palm oil,

which involves parallel cracking reactions which produces organic liquid

product (OLP), non-condensable gas and coke, and reported that the

highest yield of OLP was 60.73 % wt at O/C ratio of 32.50 and WHSV of

19 to 38 h-1.

The blends of Pongamia pinnata methyl ester (PPME) with diesel up to

40% by volume (B40) provide better engine performance (BSFC and

BSEC) and improved emission characteristics. [80]

Avinash Kumar Agarwal [98] suggested that Vegetable oils, due to

their agricultural origin, are able to reduce CO2 emissions to the

atmosphere along with import substitution of petroleum products

The cerium oxide nanoparticles can be used as additive in diesel and

diesel-biodiesel-ethanol blend to improve complete combustion of the fuel

and reduce the exhaust emissions significantly [103]

50

V.S.Hariharan [104] conducted a study on the performance,

emission and combustion characteristics of a DI diesel engine using sea

lemon oil-based fuels. The reduction in NOX emission and an increase in

smoke, hydrocarbon and CO emissions were observed for Neat sea lemon

oil compared to those of standard diesel. From the combustion analysis it

was found that ignition delay was slightly more for both the fuels tested

compared to that of standard diesel. The combustion characteristics of

sea lemon oil and its methyl ester closely followed those of standard

diesel.

M.V.Nagarhalli [119] experimented with mineral diesel and diesel

biodiesel blends in a single cylinder engine of 3.67kW at an injection

pressure of 200 bar and evaluated various aspects such as brake

thermal efficiency, brake specific energy consumption (BSEC) and found

that the emissions measured were carbon monoxide (CO), carbon dioxide

(CO2), hydrocarbon (HC), and oxides of nitrogen (NOX).On comparing

them with baseline diesel which indicated that the CO emissions were

slightly higher, HC emissions decreased from 12.8 % for B20 and 2.85 %

for B40, NOX emissions decreased up to 39 % for B20 and 28 % for B40.

The efficiency decreased slightly for blends in comparison with diesel.

The BSEC was slightly more for B20 and B40

2.11 NUMERICAL STUDIES

The result analysis with the help of mathematical and numerical

modelling of the C.I. engine. Global (peak pressures, internal energy, and

51

turbulent kinetic energy) and local (flow field, spray distribution and

temperature contours) variables are predicted for this engine during the

combustion process using the commercially available FLUENT code

(CFD).

J.Zhu [34] demonstrated a composite parallel plate channel whose

central part is occupied by a clear fluid and whose peripheral part is

occupied by a fluid-saturated porous medium is considered. The

modeling is based on the assumption that the flow is in clear fluid region

is turbulent while in the porous region the flow remains laminar. The

turbulent and laminar flow solutions are matched at the porous/fluid

interface, which is assumed rough. Two different models are utilized for

calculating turbulent viscosity in the clear fluid region, the algebraic

cebeei-smith model and a k-e model. Numerical results obtained utilizing

both models are compared and analyzed in detail

Karim van maele [49] showed that the accuracy of results of

computational fluid dynamics simulations of fires strongly depends on

the turbulence model applied when the Reynolds-averaged Navier-Stokes

approach is used. In particular, the effect of buoyancy on turbulence is

important for fire-driven flows. In this work, the standard and a

realizable k-e model are addressed. Both the simple and the generalized

gradient diffusion hypothesis are applied for the calculation of the

buoyancy production of turbulent kinetic energy. Simulation results are

presented for the axisymmetric free buoyant plume and the plane

52

buoyant wall plume. The buoyancy modification based on the simple

gradient diffusion hypothesis, has a negligible influence on the results for

both test cases. The realizable k-e model with modification based on the

generalized gradient diffusion hypothesis performs well for the test cases

considered.

Sergei S. Sazhin [51] The Distillation Curve Model for multi-

component droplets seems to be a reasonable compromise between

accuracy and CPU efficiency. The systems of equations describing droplet

heating and evaporation and auto ignition of fuel vapour/air mixture in

individual computational cells are stiff. Establishing hierarchy between

these equations, and separate analysis of the equations for fast and slow

variables may be a constructive way forward in analysing these systems

Ahmad Sana [64] demonstrated a simple relationship which has

been developed between the wall coordinate y and kolmogorov‟s length

scale using direct numerical simulation (DNS) data for a steady boundary

layer. This relationship is then utilized to modify two popular versions of

low Reynolds number k-e model. The modified models are used to

analyze a transitional oscillatory boundary layer. A detailed comparison

has been made by virtue of velocity profile, turbulent kinetic energy, and

Reynolds stress and wall shear stress with the available DNS data. It is

observed that the low Reynolds number models used in the present

study can predict the boundary layer properties in an excellent manner

53

Yoshihide Tominga [71] studied the computational fluid dynamics

(CFD) results using various revised k-e models and large eddy simulation

(LES) applied to flow around a high rise building model with 1:1:2 shape

placed within the surface boundary layer. He examines the accuracy of

various revised k-e models, i.e. LK model, MMK model and Durbin‟s

revised k-e model, by comparing their results with experimental data.

Among the computational using various revised k-e models compared

here, Durbin‟s revised k-e model shows the best agreement with the

experiment. The reason for the good performance of Durbin‟s model is

discussed on the basis of Realizability of predicted results. The second

part of the paper describes the computations based on LES with and

without inflow turbulence applied to the same flow field. The results are

compared with those of the experiments and Durbin‟s k-e model in order

to clarify the effect of velocity fluctuations on prediction accuracy for

reproducing flow behind a building. The LES results with inflow

turbulence show generally good agreement with experimental results in

terms of the distribution of velocity and turbulence energy.

S. M. Jameel Basha [102] demonstrated the gas motion inside the

engine cylinder which plays a very important role in determining the

thermal efficiency of an internal combustion engine. A better

understanding of cylinder gas motion will be helpful in optimizing engine

design parameters. An attempt has been made to study the combustion

processes in a compression ignition engine and simulation was done

54

using computational fluid dynamic (CFD) code FLUENT. An

Axisymmetric turbulent combustion flow with heat transfer is to be

modelled for a flat piston 4-stroke diesel engine. The unsteady

compressible conservation equations for mass (Continuity), axial and

radial momentum, energy, species concentration equations can express

the flow field and combustion in axisymmetric engine cylinder. Turbulent

flow modeling and combustion modeling was analyzed in formulating and

developing a model for combustion process.

Mohd Yousuf Ali [128] described the work carried out to develop a

CFD simulation model to investigate the effect of the use of hyderogen-

biodiesel dual fuel in a variable compression ratio. Diesel engine

commercial CFD software is used in this project to study the effect of

compression ratio on the performance of diesel engine.In the present

study, investigation is aimed at studying the effect of compression ratio

on the peak pressure and temperature, turbulent KE and NOx

formation.Single cylinder variable compression ratio diesel engine is

used.In this system engine is coupled to a DC dynamometer and all the

experiments are carried out at a constant speed of 1500 RPM.Hydrogen

is Inducted along with air intake.Biodiesel is injected into the

combustion chamber.The tests are carried out for the compression ratios

of 17,19,21 and 23 and each time all the parameters are noted down.

Engine exhaust emissions are also measured using an advanced AVL

five-gas analyzer. CFD and experimental values are in close proximity.

55

Ming-Liang Zhang [130] demonstrated the results from a 3D non-

linear k-e turbulence model with vegetation are presented to investigate

the flow structure, the velocity distribution and mass transport process

in a straingt compound open channel and a curved open channel. The

3D numerical model for calculating flow is setup in non-orthogonal

curvilinear co-ordinates in order to calculate the complex bound any

channel. The finite volume method is used to disperse the governing

equations and the SIMPLEC algorithm is applied to acquire the coupling

the velocity and pressure. The non-linear k-e turbulent model has good

useful value because of taking into account the isotropy and not

increasing the computational time. The water level of this model is

determined from 2D Poisson equation derived from 2D depth-averaged-

momentum equations. For concentration simulation, an expression for

dispersion through vegetation is derived in the present work for the

mixing due to flow over vegetation. The simulated results are in good

agreement with available experimental data, which indicates that the

developed 3D model can predict the flow structure and mass transport in

the open channel with vegetation

Khalid M.Saqr [131] made a new variant of the k-e turbulence

model which is used to compute the shear driven vortex flow in an open

cylinder cavity. The results are compared with published IDA

measurements for such flow configuration. The modified turbulence

56

model demonstrated good agreement with experimental results, which

further supports its validity in computing vortex dominated flows.

2.12 SUMMARY

An extended experimental study was conducted to evaluate

and compare the use of various diesel fuel supplements at blend ratios

varying from 10/90v/v to 20/80v/v. The researchers mainly

concentrated on the emission characteristics. The performance of a

Euro3-compliant diesel passenger car using 10/90v/v cotton seed oil

and diesel blend showed promising results. The higher blends of the

cotton seed oil/diesel and palm oil/diesel are mostly considered not

viable alternatives for diesel, in the emission point of view, By focusing

on the study of finding out the effects of fuel on the injection system

utilizing a modified method of friction test, which involves injecting fuel

outside combustion chamber during motoring. The researchers also used

a mechanism to preheat the palm oil. The results are comparable with

pure diesel when the heating is done above 60°C. We can conduct a

series of experiments on different vegetable oil blends varying in 25%,

50%proportions and at different load conditions varying between no load

to full load i.e. 0%, 25%, 50%, 75% and full loads.

They reported similar trends when compared to cotton seed oil and

palm oil and Neem oil. The cotton seed oil, palm oil and Neem oil

certainly show promising trends when compared to other vegetable oils.

The effect of variation of injection pressure on the performance of the C.I

57

engine using different blends i.e. 25/75v/v, 50/50v/v, of cotton seed

oil/diesel oil, palm oil/diesel oil Neem oil/diesel are generally neglected

in the literature. In the present research work, the effect of variation of

injection pressure, using different blends of cotton seed oil-diesel and

palm oil-diesel, Neem oil-diesel without preheating are studied.

2.13 SCOPE FOR PRESENT WORK

In the present work the fuels considered for investigation are

cottonseed oil Neem oil and palm oil. The fuel blends were prepared

using an emulsifier and the experiments were conducted on a single

cylinder diesel engine. The investigation is mainly focused on the

performance of the engine using the parameters like fuel consumption,

brake specific fuel consumption, brake thermal efficiency, volumetric

efficiency and exhaust gas temperature. The engine performance

parameters were calculated for each of the fuel cottonseed oil, 25C75D,

50C50D, 25P75D, 50P50D,25N75D,50N50D at 200kg/cm2, 25C75D,

50C50D, 75C25D, 25P75D, 50P50D, 50N50D at 225kg/cm2 and,

25C75D, 50C50D,25P75D, 50P50D, 50N50D at 250kg/cm2 and diesel.

Then the investigation extended to calculate engine performance

parameters at injection pressures of 200kg/cm2, 225 kg/cm2 and

250kg/cm2 for each of the fuels considered.

The increase in particulate emissions and depleting fossil fuel

reserves made us investigate the suitability of alternate fuels. In this

study, the performance of single cylinder, 4-stroke, naturally aspirated

58

direct injection compression ignition engine using blends of vegetable oils

with diesel is carried out. The comparison of various properties like

viscosity, density, flash point, fire point, cloud point etc., of diesel,

cottonseed oil, Neem oil and palm oil, and their blends have been

examined in this present work. The performance of the engine for

different blends at different injection pressure is determined and

compared with that of the diesel fuel.

The vegetable oil blends are chosen as alternate fuels as they have

a high cetane number and calorific value which is very close to diesel.

The biggest hindrance to the easy adaptation of these vegetable oils is

high viscosity and low volatility. The method adopted to decrease the

viscosity is blending the vegetable oils with diesel. In the performance

analysis, the acquired data will be useful to predict the thermal

efficiency, brake specific fuel consumption, and exhaust gas

temperature. The test results showed that brake specific fuel

consumption, exhaust gas temperature were higher for vegetable oil

blends compared to diesel where as thermal efficiency is lower for

vegetable oil blends compared to diesel. While running the engine on

different vegetable oil blends, performance parameters were very close to

diesel for lower concentration blends. Oil technologists predict that over

the next several decades, plant based oils will become just as essential

for the transportation industry as fossil fuels, like gasoline and Diesel oil,

are today. Among the many different types of alternative fuels, vegetable

59

oils and their esters come across as good choices. They are renewable, as

the carbon released by the burning of vegetable oils is used when the oil

crops undergo photosynthesis. The major differences between Diesel fuel

and vegetable oil include, for the latter, the significantly higher viscosities

and moderately higher densities, lower heating values, rise in the

stoichiometric fuel/air ratio due to the presence of molecular oxygen and

the possibility of thermal cracking at the temperatures encountered by

the fuel spray in the Diesel engines.

The objectives of this study are to examine the performance of DI

diesel engine with various blends of palm oil with diesel, cottonseed oil

with diesel and Neem oil with diesel at various loads. And also to

compute Emission characteristics of these oils. Further these

performance characteristics of blends of cotton seed oil, palm oil and

Neem oil are compared with the predicted combustion analysis of global

and local values using by the computational fluid dynamics software

(FLUENT).