10

CHAPTER-2

LITERATURE REVIEW

2.1 INTRODUCTION OF LITERATURE SURVEY

As the first phase of this research work, literature reviews pertaining to this

topic have been carried out.

2.2 NEED FOR ALTERNATE FUELS

The world is confronted with the twin crises of fossil fuel depletion and

environmental degradation. The rapid extraction and consumption of fossil fuels

have led to a reduction in petroleum reserves. Petroleum based fuels are obtained

from limited reserves. These finite reserves are highly concentrated in certain region

of the world. Therefore, those countries not having these resources are facing a

foreign exchange crisis, mainly due to the import of crude petroleum diesel. Hence

it is necessary to look for alternative fuels, which can be produced from materials

available within the country. Although vegetable oils can be fuel for diesel engines,

but their high viscosities, low volatilities and poor cold flow properties have led to

the investigation of its various derivatives. Among the different possible sources,

fatty acid methyl esters, known as Biodiesel fuel derived from triglycerides

(vegetable oil and animal fates) by trans-esterification with methanol, present the

promising alternative substitute to diesel fuels and have received the most attention

now a day. The main advantages of using Biodiesel are its renewability, better

quality exhaust gas emission, its biodegradability and the organic carbon present in

it is photosynthetic in origin. It does not contribute to a rise in the level of carbon

dioxide in the atmosphere and consequently to the green house effect (Singh 2010).

11

Biodiesel is an alternative fuel for diesel engines that is produced by

chemically combining vegetable oils and animal fats with an alcohol to form alkyl

esters. Extensive research and demonstration projects have shown that it can be

used pure or in blends with conventional diesel fuel in unmodified diesel engines.

Interest in biodiesel has been expanding recently due to government incentives and

high petroleum prices. While the current availability of vegetable oil limits the

extent to which biodiesel can replace petroleum to a few percent, new oil crops

could allow biodiesel to make a major contribution in the future (Jon et al 2007).

2.3 USE OF VEGETABLES OIL AS ALTERNATE FUELS

Avinash Kumar Agarwal (2007) studied that the Biodiesel is methyl or ethyl

ester of fatty acid made from virgin or used vegetable oils (both edible and non-

edible) and animal fat. The main resources for biodiesel production can be non-

edible oils obtained from plant species such as Jatropha curcas (Ratanjyot),

Pongamia pinnata (Karanj), Calophyllum inophyllum (Nagchampa), Hevca

brasiliensis (Rubber) etc. Biodiesel can be blended in any proportion with mineral

diesel to create a biodiesel blend or can be used in its pure form. Just like petroleum

diesel, biodiesel operates in compression ignition (diesel) engine, and essentially

require very little or no engine modifications because biodiesel has properties

similar to mineral diesel. It can be stored just like mineral diesel and hence does not

require separate infrastructure. The use of biodiesel in conventional diesel engines

results in substantial reduction in emission of unburned hydrocarbons, carbon

monoxide and particulate.

Shahid (2008) studied the use of biodiesel fuel for CI engines between 1900

and 2005. The typical edible vegetable oils such as sunflower, cottonseed, rapeseed,

soybean, palm and peanut oils were included. They recommended the rapeseed oil

and palm oil as the most suitable oils which can be used as diesel fuel extender.

They concluded in this work that neat vegetable oils can be used only for small

12

engines for a short-term period. For long-term use and for heavy/big engines, blend

of diesel and vegetable oils was recommended. Moreover, the biodiesel produced

much less NOx and HC and absolutely no SOx and no increase in CO2. In addition,

they found that indirect fuel injection system is more successful as compared to

direct injection system while using vegetable oils in place of diesel oil. However, it

should be noted that their conclusion came from their view of the limited number of

edible vegetable oils.

Anand et al (2010) investigates the effect of biodiesel and its blends varying

from B10 to B80 on the engine performance, emission and combustion

characteristics of Waste cooking oil methyl ester. The properties of diesel and

biodiesel are examined and compared. The experimental results show that the use of

Waste cooking oil methyl ester in an unmodified direct injection diesel engine has

yielded higher brake specific fuel consumption due to low calorific value. It is also

observed that at full load the brake specific energy consumption of biodiesel blends

are higher than that of diesel. Further, biodiesel blends show a reduction in emission

properties such as carbon monoxide, carbon dioxide, unburnt hydrocarbon and

smoke opacity with slight increase in nitric oxide emission compared to diesel at

full load. Overall combustion characteristics for all blends are found to be quite

similar to that of diesel. Hence, the Waste cooking oil methyl ester is a promising

diesel fuel substitute that can be produced by recycling waste cooking oil without

any engine modification and furthermore, becoming less dependent on fossil oil

imports thereby decreasing the environmental pollution.

Hossain (2010) investigates the usage of vegetable oils in CI engines. The

life-cycle output-to-input energy ratio of raw vegetable oil is around 6 times higher

than fossil diesel and is in the range of 2-6 times higher than corresponding

biodiesel. In addition, neat vegetable oil has the highest potential of reducing life-

cycle greenhouse gas emission as compared to biodiesel and fossil diesel. .

13

Moreover, raw plant oil has the highest potential of reducing life-cycle GHG

emissions as compared to biodiesel and fossil diesel

Misra (2011) experimentally determined the possibility of using

straight/unmodified vegetable oils, their blends or biodiesels and their blends with

mineral diesel as alternative fuel in order to achieve the twin objectives of reducing

the emission from the diesel engine and to increase the energy security of the

country. Jatropa seems to the answer for India's energy woes. Millions of hectares

of waste land is available in India and out of which about 33 million hectares of

wasteland has been found to be suitable for Jatropa cultivation. Jatropa seems to be

perfectly suited for India. There are many social, technical and political issues to be

sorted out before the dream of energy security through Jatropa cultivation could be

realized. The suitability of Jatropa oil blends and Jatropa biodiesel blends in running

of compression ignition has been evaluated and found that the performance of

Jatropa oil and Jatropa biodiesel blends is very close to performance of diesel in the

compression ignition engine.

Soo-Young No (2011) investigates the scope of utilizing the non-edible

vegetable oils as an alternative fuel for diesel engine is accelerated by the energy

crisis due to depletion of resources and increased environmental problems including

the great need for edible oil as food and the reduction of biodiesel production cost,

etc. Of a lot of non-edible vegetable oils which can be exploited for substitute fuel

as diesel fuel, seven vegetable oils, i.e., jatropha, karanja, mahua, linseed, rubber

seed, cottonseed and neem oils were selected. The application of jatropha oil as a

liquid fuel for CI engine can be classified with neat jatropha oil, engine

modifications such as preheating, and dual fuelling, and fuel modifications such as

jatropha oil blends with other fuels, mostly with diesel fuel, biodiesel, biodiesel

blends and degumming. Therefore, jatropha oil is a leading candidate for the

commercialization of non-edible vegetable oils. There exists a big difference in the

fuel properties of seven non-edible vegetable oils and its biodiesels considered in

14

this review. It is clear that the biodiesel generally causes an increase in NOx

emission and a decrease in HC, CO and PM emission compared to diesel. It was

reported that a diesel engine without any modification would run successfully on a

blend of 20% vegetable oil and 80% diesel fuel without damage to engine parts.

2.4 SELECTION OF NON-EDIBLE VEGETABLE OILS FOR POSSIBLE

ALTERNATIVE DIESEL FUEL

Sundarpandian (2007) developed a theoretical model to evaluate the

performance characteristics, combustion parameters and emission of vegetable oil

esters like Jatropha, Mahua and Neem Oil esters. They predicted results of these

fuels are compared with experimental results of diesel fuel. From the results, it is

found that the heat release and work done are reduced by about 4% for Atrophy, 5%

for Mahua and 8% for Neem oil esters when compared to diesel. The harmful

pollutants such HC, CO, NOx and smoke are reduced in the vegetable oil esters

compared to diesel fuel.

Venkateswara Rao et al (2008) reported the environmental impact and

potential as a green alternative fuel for diesel engine and significant modifications

of existing engine hardware required. Methyl ester of Pongamia (PME), Jatropha

(JME) and Neem (NME) are derived through trans-esterification process.

Experimental investigations have been carried out to examine properties,

performance and emission of different blends (B10, B20, and B40) of PME, JME

and NME in comparison to diesel. Results indicated that B20 have closer

performance to diesel and B100 had lower brake thermal efficiency mainly due to

its high viscosity compared to diesel. However, its diesel blends showed reasonable

efficiencies, lower smoke, CO and HC. Pongamia methyl ester gives better

performance compared to Jatropha and Neem methyl esters.

15

Sharma et al (2008) studied the advancements in development and

characterization of biodiesel, mainly concentrating the effect of the different

parameters on production of biodiesel such as molar ratio, moisture and water

content, reaction temperature, stirring, specific gravity, etc. They recommended that

developing countries are not self sufficient in the production of edible oils and

hence have emphasized in the application of a number of non-edible oils such as

jatropha, karanja, mahua, rubber seed, neem and polanga etc.

Ashwani Kumar (2011) reported the use non-edible oil (yellow oleander)

seeds that can be the reliable sustainable feedstock for biofuel production.

Furthermore, most of the non-edible seeds bearing trees have the potentials of

reclaiming wasteland and does not compete with food crop for limited growing

regions. It thus becomes imperative to search for dedicated non-edible feedstocks

and their suitability for biodiesel production.

2.5 TRANSESTERFICATION PROCESS

Hideki Fukuda et al (2001) studied that, Biodiesel (fatty acid methyl esters),

which is derived from triglycerides by trans-esterification with methanol, has

attracted considerable attention during the past decade as a renewable,

biodegradable, and nontoxic fuel. Several process for biodiesel fuel production have

been developed, among which trans-esterification using alkali-catalysis gives high

levels of conversion of triglycerides to their corresponding methyl esters in short

reaction times. This process has therefore been widely utilized for biodiesel fuel

production in a number of countries. Recently, enzymatic trans-esterification using

lipase has become more attractive for biodiesel fuel production, since the glycerol

produced as a by-product can easily be recovered and the purification of fatty

methyl esters is simple to accomplish. The main hurdle to the commercialization of

this system is the cost of lipase production.

16

Subramanian et al (2004) reported that, Trans-esterification (also called

alcoholysis) is the reaction of a fat or oil with an alcohol to form esters and glycerol.

A catalyst is usually used to improve the reaction rate and yield. Excess alcohol is

used to shift the equilibrium toward the product because of reversible nature of

reaction. For this purpose primary and secondary monohybrid aliphatic alcohols

having 1-8 carbon atoms are used.

Azame et al (2005) recommended that neem (azadirachta indica) oil was one

of the most suitable oil for use as biodiesel. Neem oil biodiesel will be used for

methyl ester produced from neem oil through Trans-esterification. The application

of neem oil to CI engine can be grouped as neat Neem oil biodiesel and its blends.

Abayeh (2007) studied the quality parameters of nerium (thevitia nerifolia)

seed oil and found to be oil content 61.88%, iodine value 62.66%, acid value

16.8%, free fatty acid 5.92%. They also compared the methyl and ethyl esters of

nerium seed oil with petroleum diesel. They conclude that the fuel properties of

nerium seed oil is a substitute fuel for Rape seed and Palm seed methyl esters.

Naoko Ellis (2008) studied that, Biodiesel is an alternative diesel fuel made

from renewable sources, is produced by the trans-esterification of oil or fat with

alcohol. In order to monitor the progress of this reaction, insite viscosity

measurements were taken using an acoustic wave solid state viscometer. The

viscometer was able to monitor the reaction until the end-point was reached, and

could therefore be adapted in the future for process control in a batch trans-

esterification reactor for biodiesel production

Ayhan Demirbas (2008) studied the comparison of trans-esterification

methods of biodiesels. Biodiesel is obtained from a chemical reaction called trans-

esterification (ester exchange). The reaction converts esters from long chain fatty

acids into mono alkyl esters. Chemically, biodiesel commonly is a fatty acid methyl

17

ester. Vegetable oils can be transesterified by heating them with excess of

anhydrous methanol and an acidic or basic reagent as catalyst. A catalyst is usually

used to improve the reaction rate and yield. In a trans-esterification reaction, a

larger amount of methanol was used to shift the reaction equilibrium to the right

side and produce more methyl esters as the proposed product. Several aspects

including the type of catalyst (alkaline, acid or enzyme), alcohol/vegetable oil molar

ratio, temperature, purity of the reactants (mainly water content) and free fatty acid

content have an influence on the course of the Trans-esterification. A non-catalytic

biodiesel production route with supercritical methanol has been developed that

allows a simple process and high yield because of the simultaneous trans-

esterification of triglycerides and methyl esterification of fatty acids. In the catalytic

supercritical methanol trans-esterification method, the yield of conversion rises to

60 90% for the first 1 min.

Samios (2009) studied a two consecutive steps basic acid trans-esterification

process (denominated trans-esterification Double Step process) for biodiesel

production from vegetable oils. The process involves homogeneous consecutive

basic acid catalysis steps and is characterized by formation of well-defined phases,

easy separation procedures, high reaction velocity and high conversion efficiency.

The proposed trans-esterification double Step process is different in relation to other

traditional two-step procedures which normally include acid esterification followed

by basic trans-esterification or enzymatic or even supercritical trans-esterification

conditions. The biodiesel (fatty acid methyl esters) was analyzed by standard

biodiesel techniques to indicating high quality and purity biodiesel products.

Xiaoling Miao et al (2009) studied the high effective acidic trans-

esterification catalyzed by trifluoroacetic acid for biodiesel production. The results

showed that the oil could be converted to biodiesel directly by one-step

trifluoroacetic acid catalyze process without extreme temperature and pressure

conditions. The optimum process combination was 2.0 M catalyst concentration

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with 20:1 M ratio of methanol to oil at temperature of 120 °C. It reduced product

specific gravity from an initial value of 0.965 to a value of 0.878 in about 5 hours of

reaction time, and the methyl ester content reached as high as 98.4%. The present

procedure represents a simple and mild method for biodiesel production in short

reaction time and with high conversion rate, which would offer potential for an

industrial process.

Patil Prafulla (2009) have experimentally optimized the biodiesel production

process for different edible and non-edible vegetable oils. The analysis of different

oil properties, fuel properties and process parameter optimization of non-edible and

edible vegetable oils were also investigated. A two-step and single-step trans-

esterification process was used to produce biodiesel from high free fatty acid (FFA)

non-edible oils and edible vegetable oils, respectively. This process gives yields of

about 90 95% for Jatropha curcas, 80 85% for Pongamia glabra, 80 95% for

canola, and 85 96% for corn using potassium hydroxide (KOH) as a catalyst. The

fuel properties of biodiesel produced were compared with ASTM standards for

biodiesel.

Singh (2010) studied the characterization of vegetable oils and their methyl

ester as the substitute of the petroleum fuel and future possibilities of biodiesel

production. Although vegetable oils can be fuel for diesel engines, but their high

viscosities, low volatilities and poor cold flow properties have led to the

investigation of its various derivatives. Among the different possible sources, fatty

acid methyl esters, known as biodiesel fuel derived from triglycerides (vegetable oil

and animal fats) by trans-esterification with methanol, present the promising

alternative substitute to diesel fuels and have received the most attention.

Man Kee Lam et al (2010) suggested that, biodiesel is a renewable,

biodegradable and non-toxic fuel which can be easily produced through trans-

esterification reaction. It was found that using heterogeneous acid catalyst and

19

enzyme are the best option to produce biodiesel from oil with high free fatty acids

as compared to the current commercial homogeneous base-catalyzed process.

However, these heterogeneous acid and enzyme catalyze system still suffer from

serious mass transfer limitation problems and therefore they are not favorable for

industrial application. Latest technological developments that have the potential to

overcome the mass transfer limitation problem such as oscillatory flow reactor,

ultrasonication, microwave reactor and co-solvent are also reviewed. With proper

research focus and development, waste cooking oil can indeed become the next

ideal feedstock for biodiesel.

Leung (2010) investigated that, biodiesel is generally produced through the

yzed by

both acidic and basic catalysts. Biodiesel is a liquid which varies in colour between

golden and dark brown depending on the production feedstock. It is practically

immiscible with water, has a high boiling point and low vapour pressure. Typical

methyl ester biodiesel has a flash point of 150 °C (300 °F). Biodiesel has a density

of 0.88 g/cm³, less than that of water. Biodiesel uncontaminated with starting

material can be regarded as non-toxic.

Dennis (2010) reported that, biodiesel is a low-emission diesel substitute fuel

made from renewable resources and waste lipid. The most common way to produce

biodiesel is through trans-esterification especially alkali-catalyzed Trans-

esterification. When the raw materials (oils or fats) have a high percentage of free

fatty acids or water, the alkali catalyst will react with the free fatty acids to form

soaps. The water can hydrolyze the triglycerides into diglycerides and form more

free fatty acids. Both of the above reactions are undesirable and reduce the yield of

the biodiesel product. In this situation, the acidic materials should be pre-treated to

inhibit the saponification reaction.

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Balat (2010) analyzed a few different ways to make biodiesel, but most

manufacturing facilities produce industrial biodiesel through a process called Trans-

esterification. In this process, the fat or oil is first purified and then reacted with an

alcohol, usually methanol (CH3OH) or ethanol (CH3CH2OH) in the presence of a

catalyst such as potassium hydroxide (KOH) or sodium hydroxide (NaOH). When

this happens, the triacylglycerol is transformed to form esters and glycerol. The

esters that remain are what we then call biodiesel.

Dibakar Chandra Deka (2011) reported that the biodiesel can be produced

from Yellow Nerium oleander seed oil. Trans-esterification of the oil to biodiesel

was carried out in methanol by batch reaction using a heterogeneous catalyst

derived from the trunk of Musa balbisiana Colla (one variety of banana plant). 96

wt. % of the oil is converted to biodiesel at 32°C in 3 hours. The weight %

composition of the biodiesel is methyl oleate 43.72, methyl palmitate 23.28, methyl

linoleate 19.85, methyl stearate 10.71 and methyl arachidate 2.41. The biodiesel is

free from sulfur and has exhibited a high cetane number of 61.5. Excellent quality

biodiesel has been prepared in high yield from yellow oleander seed oil using a

catalyst derived from the trunk of Musa balbisiana Colla for the first time. Fuel

properties such as density, cetane number, cetane index, kinematic viscosity, pour

point, flash point, and cloud point, cold filter plugging point, calorific value,

lubricity, ramsbottom carbon residue, refractive index, acid value and iodine value

are evaluated and recorded. The investigation has established the yellow oleander

seed oil as highly promising feedstock for biodiesel industries.

2.6 PRODUCTION OF NON-EDIBLE OIL SEEDS

Balusamy (2007), Nabi et al (2006), Azam et al (2005), Karmee (2005) and

Ramadhas et al (2005) reported the productions of non edible oil seed yield

percentage in India are given in Table 2.1.

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Table 2.1 Estimated yield of non-edible oil seed

Scientific name

Oil seed yield (kg/ha)

Azadirachta indica (Neem) 2670

Calophyllum inophyllum (Polanga) 4680

Hevea brasiliensis (Rubber) 40 50

Jatropha curcas (Physic nut) 1900 2500

Pongamia (Millettia) pinnata/Pongamia

glabra (Koroch, karanja) 225 2250

Ricinus communis (Castor) 450

Thevetia peruviana (Yellow oleander) 1575

2.7 PROPERITIES OF BIOIESEL

Ramadhas et al (2006) compared the fuel properties of methyl esters

obtained from non-edible vegetable oils are shown in Table.2.2. Biodiesel is

completely miscible with diesel and can be blended in any proportion to diesel fuel.

It is found from that most of fuel properties of several biodiesels are within the

standards.

Balusamy (2008) compared the fuel properties of Nerium (thevetia

peruviana) seed oil with other biofuels and diesel as fuel for CI engine is shown in

Table 2.3. It is found from that fuel properties of methyl ester of Nerium were

significantly better than other biofuels.

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Table 2.2 Fuel properties of biodiesels

Property

JOME

KOME

MOME

NOME

Density (kg/m3,

40 °C) 862 886 865 898 828 865 820 942

Viscosity

(mm2/s, 40 °C) 3.0 5.65 3.8 9.6 2.7 6.2 3.2 10.7

Flash point (°C) 180 280 110 187 56 208

Pour point (°C) 2 6 6 to 14 1 6

Cloud point (°C) 4 10 2 to 24 3 5

Cetane number 43 59 36 61 47 51 51 53

Calorific value

(MJ/kg) 37.2 43.0 36.0 42.1 36.8 43.0 39.6 40.2

Table 2.3 Properties of methyl ester of biofuels of various origins and diesel

Property

Diesel Nerium Jatropha Pangumia Mahua Neem

Calorific

Value(KJ/Kg)

43200 42652 42250 42334 42062 41905

Specific

Gravity

0.804 0.828 0.8157 0.8212 0.815 0.829

Viscosity at 40

(°C)

3.9 6.5 4.84 6.4 4.8 6.8

Cetane number 49 51 48 50 47 50

Flash point

(°C)

56 88 92 95 85 87

Fire point

(°C)

64 95 96

98 92 93

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Haldar et al (2009) compared the fuel properties of seven non-edible

vegetable oils with diesel fuel are shown Table 2.4. Because of the low cetane

number and high kinematic viscosity of the non-edible vegetable oil, several

problems occurred in diesel engines such as engine choking, cease of fuel injector,

gum formation and piston sticking under long term use may occur.

Table 2.4 Fuel properties of seven non-edible vegetable oils and diesel

Property

Jatropha

Karanja

Mauha

Linseed

Rubber

seed

Cottonseed

Neem

Diesel

Density

(kg/m3,

40 °C)

901 940 870 928 891 960 865 950 910 930 911 921 912 965 830 850

Viscosity

(mm2/s,

40 °C)

24.5

52.76 27.8 56

24.6

37.6

16.2

36.6

34.0

76.4 32.8 36.0

20.5

48.2 2.0 2.7

Flash

point

(°C)

180 280 198 263 212 260 108 242 144 198 210 243 34 285 45

Cetane

number 33.7 51 45 67 43.5 28 35 37 41.2 59.5 51 45

Calorific

value

(MJ/kg)

38.20

42.15

34.0

38.8

35.6

38.9

37.7

39.8 37.5 39.5 40.1

33.7

39.5 42 44

2.8 USE OF JATROPHA OIL TO CI ENGINE

Kumar (2003) investigated the performance of neat jatropha oil in the

application to the single cylinder water-cooled direct injection diesel engine

developing a power output of 3.7 kW at the rated speed of 1500 rpm at various

output have been investigated as the basis for comparison with the blending,

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biodiesel and dual fuel operation techniques. They found that jatropha oil resulted in

slightly reduced thermal efficiency as compared to diesel. HC emission was higher

with jatropha oil as compared to diesel. The maximum smoke level with jatropha oil

was highest among that of its ester and diesel. Ignition delay was higher with neat

jatropha oil. In addition, lower heat release rate was found with jatropha oil.

Pramanik (2003) studied the blends of varying proportions of jatropha oil

with diesel and compared with diesel fuel in a single cylinder compression ignition

engine. Significant improvement in engine performance was observed compared to

vegetable oil alone. The specific fuel consumption and the exhaust gas temperature

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

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

of jatropha oil.

Deepak Agarwal (2007) studied the performance and emission

characteristics of Jatropha oil (preheated and blends) in a direct injection

compression ignition engine. In the present research, experiments were designed to

asing the fuel

temperature and thereby eliminating its effect on combustion and emission

characteristics of the engine. Experiments were also conducted using various blends

of Jatropha oil with mineral diesel to study the effect of reduced blend viscosity on

emission and performance of diesel engine. While operating the engine on Jatropha

oil (preheated and blends), performance and emission parameters were found to be

very close to mineral diesel for lower blend concentrations.

Sundaresan (2007) tested the blends of 25, 50, 75 and 100% by volume of

jatropha oil methyl ester with diesel in single cylinder diesel engine. They found

that brake thermal efficiency of jatropha oil methyl ester blends was comparable

with diesel fuel at all loads. For pollutant emission, NOx emission from the blends

25

of jatropha methyl ester was comparatively higher, smoke emission was lower and

CO emission was also lower at peak load than diesel fuel.

Ramesh (2008) investigated the performance of a 5.2 kW diesel engine with

alternator to test jatropha biodiesel and its blends. In the case of jatropha biodiesel

alone, the fuel consumption in the diesel engine was about 14 per cent higher than

that of diesel. The percent increase in specific fuel consumption ranged from 3 to 14

for B20 to B100 fuels. The brake thermal efficiency for biodiesel and its blends was

found to be slightly higher than that of diesel fuel at tested load conditions and there

was no difference between the biodiesel and its blended fuels efficiencies. For

jatropha biodiesel and its blended fuels, the exhaust gas temperature increased with

increase in load and amount of biodiesel. The highest exhaust gas temperature was

observed as 463ºC for biodiesel among the three load conditions. The diesel mode

exhaust gas temperature was observed as 375ºC. The CO2 emission from the

biodiesel fuelled engine was slightly higher than diesel fuel as compared with

diesel. The carbon monoxide reduction by biodiesel was 16, 14 and 14 per cent at 2,

2.5 and 3.5 kW load conditions. The NOx emission from biodiesel was increased by

15, 18 and 19 per cent higher than that of the diesel at 2, 2.5 and 3.5 kW load

conditions respectively.

Bhardwaj (2008) tested the blends of jatropha oil methyl ester with diesel

fuel (B10 and B20) in the sports utility vehicle equipped with a common rail direct

injection system It should be noted that this study is different with other

investigations up to now in terms of the applicability of vegetable oils and its

derivatives to the very high injection pressure system which is very sensitive to the

fuel type and its quality. They concluded that the blends of jatropha oil methyl ester

and diesel can replace the diesel fuel up to 10% (by volume) content for running

existing common rail direct injection system without any durability problems.

26

Chauhan et al (2010) conducted an experimental study on the performance

and emission characteristics of compression ignition engine fuelled with Jatropha

oil methyl ester. The experimental results showed that the thermal efficiency of the

engine was lower, while the brake specific fuel consumption was higher with

Jatropha oil compared with diesel fuel. The level of NOx emission from Jatropha oil

methyl ester during the entire experimental condition was lower than those of diesel

fuel. However, CO, HCandCO2 emission from Jatropha oil methyl ester was higher

than those of diesel fuel.

2.9 USE OF MAHUA OIL TO CI ENGINE

Puhan (2005) performed a test of mahua oil methyl ester with diesel fuel in a

single cylinder direct injection compression ignition engine and showed decrease

(13%) in thermal efficiency. In the continuing work, Puhan (2005) tested mahua oil

ethyl ester with diesel fuel in a same engine with the previous study and showed the

comparable thermal efficiency with diesel fuel. They pointed out that this is due to

the chemical composition of mahua oil ethyl ester, which promotes the combustion

process. It should be pointed out that the viscosity of mahua oil ethyl ester

(6.2mm2/s at40 8C) is slightly higher than that of mahua oil methyl ester (5.2

mm2/s at40 8C).

Agarwal et al (2008) investigated the performance and exhaust emission of

mahual oil blends in a four- stroke diesel engine and compared it with diesel fuel. It

was observed by them that all mahua oil blends (10, 20 and 30%) have almost

similar thermal efficiency and are very close to the thermal efficiency of diesel fuel.

It should be pointed out that 30% mahua oil blend is found to be most thermally

efficient from their work. It was also found that smoke density is higher for mahua

oil blends compared to diesel at lower loads. Smoke density increased with

proportion of mahual oil in diesel.

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Kapilan (2009) experimental studied an Engine tests with mahua oil methyl

ester on a single cylinder compression ignition engine at different injection opening

pressures and loads. When mahua oil was used as fuel in the compression ignition,

it results in lower thermal efficiency and higher smoke emission due to its higher

viscosity and lower volatility. Hence in the present work, biodiesel was derived

from mahua oil using Trans-esterification process and the effect of injector nozzle

opening pressure on the performance of the direct injection , CI engine was studied.

The engine tests were conducted on a single cylinder, naturally aspirated, water

cooled, diesel engine, which is used in the agricultural machinery, at different

injector nozzle opening pressures and loads. The engine performance with mahua

oil biodiesel was compared with neat diesel operation. From the engine tests, it is

observed that the higher injector nozzle opening pressure of 200 bar results in better

brake thermal efficiency and lower smoke, CO and HC emissions as compared to

other injector nozzle opening pressures. But there was a slight increase in the NOx

emission at this injector nozzle opening pressure. The engine performance with the

mahua oil biodiesel results in lower CO, HC and smoke emissions and slightly

higher NOx emission. Also the engine efficiency with mahua oil biodiesel is close

to diesel. From the present work, it is concluded that the biodiesel derived from

underutilized and non-edible mahua oil can be used as a renewable and alternative

fuel for the CI engine.

Godignur et al (2009) tested the performance and emission characteristics of

turbocharged direct injection compression ignition engine fuelled with diesel,

Mahua oil biodiesel and its blends at constant speed of 1500 rpm under variable

load conditions. Neat mahua oil poses some problems when subjected to prolonged

usage in CI engine. The Trans-esterification of mahua oil can reduce these

problems. The use of biodiesel fuel as substitute for conventional petroleum fuel in

heavy-duty diesel engine is receiving an increasing amount of attention. The

volumetric blending ratios of biodiesel with conventional diesel fuel were set at 0,

20, 40, 60, and 100. Engine performance (brake specific fuel consumption, brake

28

specific energy consumption, thermal efficiency and exhaust gas temperature) and

emissions (CO, HC and NOx) were measured to evaluate and compute the behavior

of the diesel engine running on biodiesel. The results indicate that with the increase

of biodiesel in the blends CO, HC reduces significantly, fuel consumption and NOx

emission of biodiesel increases slightly compared with diesel. Brake specific energy

consumption decreases and thermal efficiency of engine slightly increases when

operating on 20% biodiesel than that operating on diesel.

Bora et al (2009) repoted that, mahua oil biodiesel as supplementary diesel

fuel .They found that the fuel properties of mahua oil biodiesel were within the

limits specifiedbyASTMD6751-2 and IS 1448 standards. The addition of mahua oil

biodiesel to diesel fuel had significantly reduced CO, HC and smoke emission but

increase in NOx emission slightly. They results showed that no remarkable power

reduction in the engine operation when operated with blends of mahua oil biodiesel

and diesel fuel. There was slight increase in brake specific fuel consumption and

decrease in brake thermal efficiency for mahua oil biodiesel and its blends

compared to diesel fuel.

Saravanan et al (2010) studied the performance and emission characteristics

of mahua oil methyl ester. Biodiesel is a fatty acid alkyl ester, which is renewable,

biodegradable and non-toxic fuel which can be derived from any vegetable oil by

Trans-esterification. One of the popularly used biodiesel in India is Mahua oil

(MadhucaIndica). In the present investigation Mahua oil was transesterified using

methanol in the presence of alkali catalyst and was used to study the performance

and emission characteristics. The biodiesel was tested on a single cylinder, four

stroke compression ignition engine. Engine performance tests showed that power

loss was around 13% combined with 20% increase in fuel consumption with Mahua

oil methyl ester at full load. Emissions such as carbon monoxide, hydrocarbon were

lesser for Mahua ester compared to diesel by 26% and 20% respectively. Oxides of

nitrogen were lesser by 4% for the ester compared to diesel.

29

2.10 USE OF KARANJA OIL TO CI ENGINE

Raheman (2004) tested the blends of karanja oil biodiesel and petro diesel

from 20% to 80% by volume in a single cylinder, four-stroke direct injection diesel

engine having a rated output of 7.5 kW at 3000 rpm and a compression ratio of

16:1. The maximum brake thermal efficiencies were obtained to be 26.79 and

26.19% for B20 and B40 respectively, which were higher than that of diesel

(24.62%). The lower brake thermal efficiency obtained for B60 B100 could be due

to a reduction in the calorific value and an increase in fuel consumption as

compared to B20.

Muralidharan et al (2004) studied the performance and smoke emission of

different proportions of karanja oil biodiesel blends with diesel fuel (5, 10, and

15%) in direct injection diesel engine under different operating conditions. They

conclude that karanja oil biodiesel of 10% blend with diesel fuel is an ideal

alternative fuel for diesel engine.

Srivastava et al (2008) tested different blends with karanja oil biodiesel in

two cylinder diesel engine. They concluded that the thermal efficiency is lower with

biodiesel of karanja oil as compared to diesel, whereas thermal efficiency of

blending is higher than that of biodiesel. They have also reported that HC, CO and

NOx emission from karanja oil methyl ester were slightly higher as compared with

conventional diesel fuel. HC emission of diesel at maximum load was 85 ppm,

while that of biodiesel was 120 ppm due to poor mixing with air. CO emission of

diesel at maximum load was reported to be 0.18% as compared to 0.21% of

biodiesel. However, emission was lower for blends as compared to biodiesel. The

emission are 0.15%, 0.16%, 0.15% and 0.18% with blends of 5%, 10%, 15% and

20%, respectively, at maximum load. NOx emission in the case of biodiesel was

higher than that of blends of karanja biodiesel. It was also reported that NOx

30

emission in the case of biodiesel is approximately 12% higher than that of diesel

fuel, which may be due to the higher temperature of biodiesel combustion chamber.

Baiju et al (2009) studied the compression ignition engine characteristics

using methyl and ethyl esters of karanja oil. Even though the physical and chemical

properties of ethyl esters were comparable with that of methyl esters, viscosity of

ethyl esters was slightly higher than that of methyl esters. Cold flow properties of

ethyl esters were better than those of methyl esters. In the performance test, results

show that methyl esters produced slightly higher power than ethyl esters. Exhaust

emission of both esters were almost identical. NOx emission increased by 10 25%

when fuelled with neat biodiesel and karanja biodiesel fuel blends as compared to

conventional diesel fuel at part loads. However, NOx emission decreased at full

load. Exhaust emission such as CO, HC and smoke were reduced with the use of

neat biodiesel and the blends.

2.11 USE OF NEEM OIL TO CI ENGINE

Nurun Nabi et al (2006) reported the combustion and exhaust emission with

neat diesel fuel and neem biodiesel blends in a four stroke naturally aspirated direct

injection diesel engine. Compared with conventional diesel fuel, neem biodiesel

blends showed lower carbon monoxide (CO), and smoke emission but higher oxides

of nitrogen (NOX) emission. However, compared with the diesel fuel, NOX emission

with neem biodiesel blends was slightly reduced when exhaust gas re-circulation

was applied.

Rao et al (2008) compared the performance and emission characteristics of

neat neem oil and neem oil blends (25%) with diesel with diesel fuel. They found

that neem oil showed lower NOx emission when compared with diesel and neem oil

blends. Neem oil blends with diesel showed slightly higher smoke intensities than

diesel. CO and HC emission of neem oil blends were lower compared to their neat

31

neem oil and mineral diesel. The brake thermal efficiency of neat neem oil and its

blends were comparable diesel fuel.

Venkateswara Rao et al (2008) conducted experimental investigations of

performance and emission of different blends (B10, B20, and B40) of pongamia oil

methyl ester, jatropha oil methyl ester and neem oil methyl ester in comparison to

diesel. Results indicated that B20 have closer performance to diesel and B100 had

lower brake thermal efficiency mainly due to its high viscosity compared to diesel.

However, its diesel blends showed reasonable efficiencies, lower smoke, CO and

HC.

Anbumani (2010) studied the feasibility of using two edible plant oils,

mustard and neem oil butyl ester on a compression ignition engine. Results have

indicated that engine run at 20% blend of oils showed a closer performance to pure

diesel. However, mustard oil at 20% blend with diesel gave best performance as

compared to neem oil blends in terms of low smoke intensity, emission of HC and

NOx. All the parameters tested viz., total fuel consumption, specific energy

consumption; specific fuel consumption, brake thermal efficiency and cylindrical

peak pressure were improved.

2.12 USE OF NERIUM OIL TO CI ENGINE

Balusamy (2008) compared the performance, combustion and emission

characteristics of methyl ester of nerium (thevetia peruviana) seed oil with other

methyl esters of vegetable oils namely jatropha, pungamia, mahua, neem, corn,

palm, cotton, mustard, sunflower and rice bran oils at a blend ratio of 1:5 (B20).

They concluded that the 20% methyl ester of nerium seed oil and 80% diesel could

be used as a fuel for diesel engine for better performance with less emission when

compared to other methyl esters.

32

Dilip Kumar Bora (2009) experimentally invested the performance of single

cylinder diesel engine using blends of nerium (karabi) seed biodiesel. It has been

observed that, BTE decreased with increase in proportion of biodiesel in blends.

Smoke, HC and CO in exhaust emission reduced, whereas NOX increased with

increase in percentage of nerium biodiesel in blends.

Kannan (2010) studied an oxygenated additive diethyl ether blended with

nerium (thevetia peruviana) bio diesel in the ratios of 5%, 10%, 15% and 20% and

tested for their performance. They concluded that 20% diethyl ether blend with

nerium biodiesel would result in better performance and lesser emission than other

combinations.

Kannan (2011) studied the effect of nerium (thevetia peruviana) biodiesel

emulsified with water in the ratios of 5%, 10%, 15% and 20% to investigate the

engine performance and emission characteristics. Emulsified fuels showed an

improvement in brake thermal efficiency accompanied by the drastic reduction in

NOx. From the detailed study it was found that 15% water emulsified fuel showed

the best performance and less emission than the other combinations.

2.13 USE OF BIODIESEL IN CI ENGINE

Desantes et al (2004) experimental studied the effects of injection rate

shaping on the combustion process and exhaust emission of a direct-injection diesel

engine. Boot-type injections were generated by means of a modified pump-line-

nozzle system, which is able to modulate the instantaneous fuel injection rate. The

interest of the study reported here was the evaluation of the effective changes

produced in the injection rate at different engine operating conditions, when the

engine rotating speed and the total fuel injected were changed. In addition, the

influence of these new injection rates was quantified on the global engine

performance and pollutant emission. In particular, the focus was placed on

33

- reducing

NOX emission.

Basinger et al (2010) reported the design methodology for the modifications

and a suite of performance test results are described including fuel consumption,

efficiency, pre-combustion chamber pressure, and various emission. The results of

the study show how the combination of preheating the high pressure fuel line,

advancing the injector timing and increasing the injector valve opening pressure

allows the engine to efficiently utilize plant oils as a diesel fuel substitute,

potentially aiding remote rural farmers with a lower cost, sustainable fuel source

enabling important agro-processing mechanization in parts of the world that needs it

most.

Hossain et al (2010) reported the regarding engines performance, exhaust

emission and engines durability for compression ignition engine. The causes of

technical problems arising from the use of various oils were discussed and the

modifications to oil and engines employed to alleviate these problems. The review

shows that a number of plant oils can be used satisfactorily in C.I engines, without

Trans-esterification, by preheating the oil and/or modifying the engines parameters

and the maintenance schedule. As regards life-cycle energy and greenhouse gas

emission and these reveal considerable advantages of raw plant oils over fossil

diesel and biodiesel. Typical results show that the life-cycle output-to-input energy

ratio of raw plant oil is around 6 times higher than fossil diesel. Depending on either

primary energy or fossil energy requirements, the life-cycle energy ratio of raw

plant oil is in the range of 2 6 times higher than corresponding biodiesel.

Amba Prasad Rao et al (2011) experimentally studied a mechanically

operated simple component, variable timing fuel injection cam, is designed for a

510 cc automotive type naturally aspirated, water-cooled, direct injection diesel

engine. Modifications in the fuel injection cam and gear train are carried out to suit

34

the existing engine configuration. Variable speed tests are carried out for testing the

efficiency of component on both engine and chassis dynamometers for performance

and emission. It is observed that the engine which is already retarded could further

be retarded with variable timing fuel injection cam. Significant reductions in NOx

and smoke emission levels are achieved.

Jinlin Xue et al (2011) reported the effect of biodiesel on engine power,

economy, durability and emission including regulated and non-regulated emission,

and the corresponding effect factors. The use of biodiesel leads to the substantial

reduction in PM, HC and CO emission accompanying with the imperceptible power

loss, the increase in fuel consumption and the increase in NOX emission on

conventional diesel engine with no or fewer modification. And it favors to reduce

carbon deposit and wear of the key engine parts. Therefore, the blends of biodiesel

with small content in place of petroleum diesel can help in controlling air pollution

and easing the pressure on scarce resources without significantly sacrificing engine

power and economy. However, many further researches about optimization and

modification on engine, low temperature performances of engine, new

instrumentation and methodology for measurements, etc., should be performed

when petroleum diesel is substituted completely by biodiesel.

2.14 PERFORMANCE UNDER DIFFERENT INJECTION TIMINGS

Suryawanshi (2005) reported that, the injection timing variations have a

strong effect on NOx emission for direct injection diesel engines. Retarded injection

is commonly used to control NOx emission. The methyl ester of pongamia oil,

known as biodiesel, is receiving increasing attention as an alternative fuel for diesel

engines. In the present investigation neat pongamia oil methyl esteras well as the

blends of varying proportions of pongamia oil methyl ester and diesel were used to

run a compression ignition engine with standard injection timing and retarded

injection timing. Significant improvements in engine performance and emission

35

characteristics were observed for pongamia oil methyl ester fuel. The addition of

pongamia oil methyl ester to diesel fuel has significantly reduced HC, CO, and

smoke emission but it increases the NOX emission slightly with standard injection

timing. The NOX emission was decreased with retarded injection timing with

negligible effect on fuel consumption rate. Similar trend in brake thermal efficiency

and exhaust gas temperature was observed with retarded injection timing while

maximum cylinder gas pressure and ignition delay was decreased.

Reddy (2006) reported the experimental work on a compression ignition

engine fuelled with jatropha oil. They found that when the injection timing is

retarded with enhanced injection rate, a significant improvement in performance

and emission was noticed. At full output, NOX level and smoke with jatropha oil are

1162.5 ppm and 2 BSU, respectively, while they are 1760 ppm and 2.7 BSU with

diesel. It was found that the brake thermal efficiency increases when the injection

rate is lowered with jatropha oil. They concluded that a significant improvement in

performance, emission and combustion parameters can be obtained by properly

optimizing the injector opening pressure, injection timing, injection rate and

enhancing the swirl level when a diesel engine is to be operated with neat jatropha

oil.

Dhananjaya et al (2008) reported that, acceptable brake thermal efficiency,

brake specific energy consumption and emission characteristics in a single cylinder

compression ignition engine were obtained up to B25 of jatropha oil methyl ester

and diesel fuel. With the increased injector opening pressure and advancing the

injection timing, B20 jatropha oil methyl ester blend fuel with semi-adiabatic

engine showed better combustion performance and lower exhaust emission

compared to other blends.

Manieniyan (2008) performed the experimental investigation for

performance, combustion and emission characteristics of single cylinder direct

36

injection compression ignition engine fuelled with various jatropha biodiesel blends

(B20, B40, B60, and B80). They found that brake thermal efficiency decreases with

increase in percentage of jatropha oil biodiesel blends. However, the brake thermal

efficiency of B20 (32.22%) was nearly similar to that of diesel (32.71%).

Cenk Sayin (2008) studied the influence of injection timings on the exhaust

emission of a single cylinder, four stroke, direct injection, naturally aspirated diesel

engine has been experimentally investigated using ethanol blended diesel fuel from

0% to 15% with an increment of 5%. The engine has an original injection timing

27° BTDC. The tests were performed at five different injection timings (21°, 24°,

27°, 30°, and 33° BTDC) by changing the thickness of advance shim. The

experimental test results showed that NOx and CO2 emission increased as CO and

HC emission decreased with increasing amount of ethanol in the fuel mixture.

When compared to the results of original injection timing, at the retarded injection

timings (21° and 24° BTDC), NOx and CO2 emission increased, and unburned HC

and CO emission decreased for all test conditions. On the other hand, with the

advanced injection timings (30° and 33° BTDC), HC and CO emission diminished,

and NOx and CO2 emission boosted for all test conditions.

Flavio Caresana (2011) reported the primary mechanism by which biodiesel

increases NOx emission is by an inadvertent advance in the start of injection

timings, caused by a higher modulus and viscosity. However, more recent studies

show that NOx emission also increase in biodiesel-fuelled common rail engines,

and that in some cases they actually decrease in engines with mechanically

controlled fuel injection systems. The present study provides a contribution to the

discussion in this field by describing a new method to evaluate the injection

advance in engines with mechanically controlled pumps. The experimental data

show that the advances in the start of injection timings, using biodiesel rather than

mineral diesel, are smaller than those calculated with standard methods and may

even not occur at all, depending on injection system design. In addition, they

37

demonstrate that, contrary to common belief, injection pressure does not always

increase when using biodiesel. These data may help explain why some researchers

have found similar or even reduced NOx emission also with mechanical injection

systems.

Shivakumar et al (2011) reports the investigation influence of injection

timing on the performance and emission of a single cylinder, four stroke stationary,

variable compression ratio, diesel engine was studied using waste cooking oil

(WCO) as the biodiesel blended with diesel. The tests were performed at three

different injection timings (24°, 27°, 30° CA BTDC) by changing the thickness of

the advance shim. The experimental results showed that brake thermal efficiency

for the advanced as well as the retarded injection timing was lesser than that for the

normal injection timing (27° BTDC) for all sets of compression ratios. Smoke, un-

burnt hydrocarbon (UBHC) emission were reduced for advanced injection timings

where as NOX emission increased.

Anand et al (2011) reported the experimental work on a turbocharged, direct

injection, multi-cylinder truck diesel engine fitted with mechanical distributor type

fuel injection pump using biodiesel-methanol blend and neat karanji oil derived

biodiesel under constant speed and varying load conditions without altering

injection timings. The results of the experimental investigation indicate that the

ignition delay for biodiesel -methanol blend is slightly higher as compared to neat

biodiesel and the maximum increase is limited to 1°. The maximum rate of pressure

rise follow a trend of the ignition delay variations at these operating conditions.

However, the peak cylinder pressure and peak energy release rate decreases for

biodiesel -methanol blend. In general, a delayed start of combustion and lower

combustion duration are observed for biodiesel -methanol blend compared to neat

biodiesel fuel. A maximum thermal efficiency increase of 4.2% due to 10%

methanol addition in the biodiesel is seen at 80% load and 16.67 s 1 engine speed.

The unburnt hydrocarbon and carbon monoxide emission are slightly higher for the

38

methanol blend compared to neat biodiesel at low load conditions whereas at higher

load conditions unburnt hydrocarbon emission are comparable for the two fuels and

carbon monoxide emission decrease significantly for the methanol blend. A

significant reduction in nitric oxide and smoke emission are observed with the

biodiesel-methanol blend investigated.

2.15 PERFORMANCE UNDER DIFFERENT INJECTION PRESSURE

Monyem et al (2001) studied the effect of injection and combustion timing

on biodiesel combustion and exhaust emission. A John Deere diesel engine was

fueled with two different biodiesel fuels, one of which had been deliberately

oxidized, and with their 20% blends with No. 2 diesel fuel. The range of injection

timings studied produced changes of 50% and 34% in the CO and HC emission,

respectively. A common linear relationship was found between the start of injection

and the NOx emission for all the fuels studied. When compared at the same start of

combustion, the neat biodiesel produced lower NOx emission than the No. 2 diesel

Ismet Celikten (2003) has experimentally investigated the effect of injection

pressure on engine performance and exhaust emission on a four cylinder stroke

turbo indirect diesel engine. Emission and performance values such as torque,

power, brake mean effective pressure, specific fuel consumption, and fuel flow

were measured for both full load and part load by changing the injection pressure

from 100 to 250 bar and at 50%, 75% and 100% throttle positions of turbocharger.

When the fuel injection pressure is low, fuel particle diameters will enlarge and

ignition delay period during the combustion will increase. Due to this NOX and CO

emission also increases since combustion process deteriorates. When injection

pressure is increased fuel particle diameters will become small. Since the formation

of mixing of fuel to air becomes better during ignition delay period, smoke level

and CO emission will be less. But, if injection pressure is too high ignition delay

becomes shorter. So, the possibilities of homogeneous mixing decrease and

39

combustion efficiency falls down. Therefore, smoke is formed at the exhaust of the

engine.

Yakup Icingur (2003) experimentally analyzed the effect of fuel injection

pressure and cetane number on direct injection diesel engine emission. Test were

conducted at full engine load on a four stroke four cylinder direct injection diesel

engine with fuel cetane numbers of 46, 51, 54.5,and 61.5 at different injection

pressures of 100 bar, 200 bar and 250 bar by varying the engine speed from 1000

rpm to 4500 rpm. NOX is found decreasing for increasing in engine speed with

increase in cetane number. For an ijection pressure of 150 bar, NOX emission

decreases about 10% when the fuel cetane number is increased for 46 to 61.

Can cinar (2005) studied the effect of injection pressure and intake CO2

concentration on performance and emission parameters in IDI turbocharged diesel

engine. They concluded that specific fuel consumption deteriorates with increasing

injection pressure and intake CO2 concentration. NOX emission was found to be

higher for moderate injection pressure at low CO2 concentration. They also reported

that NOX emission decreases drastically as the intake CO2 concentration increases.

Due higher heat capacity of intake CO2, it will absorb more combustion enthalpy

and consequently reduces maximum in-cylinder temperature and NOX formation.

Mahanta (2006) concluded that 15 20% karanja oil biodiesel-diesel blend

(B15 and B20) could be a better fuel in terms of fuel efficiency and power

developed. Results obtained with B15 and B20 showed improvement in brake

thermal efficiency and reduction in brake specific fuel consumption, especially at

higher load. Remarkable reduction in CO and HC emission for B15 and B20 at

medium and higher power output was obtained.

Avinash Kumar Agarwal et al (2008) proposed an experimental investigation

has been carried out to analyze the performance and emission characteristics of a

40

compression ignition engine fuelled with Karanja oil and its blends (10%, 20%,

50% and 75%). The effect of temperature on the viscosity of Karanja oil has also

been investigated. Fuel preheating in the experiments for reducing viscosity of

Karanja oil and blends has been done by a specially designed heat exchanger, which

utilizes waste heat from exhaust gases. A series of engine tests, with and without

preheating/pre-conditioning have been conducted using each of the above fuel

blends for comparative performance evaluation. The performance parameters

evaluated include thermal efficiency, Brake specific fuel consumption, brake

specific energy consumption and exhaust gas temperature whereas exhaust emission

include mass emission of CO, HC, NOx and smoke opacity. These parameters were

evaluated in a single cylinder compression ignition engine typically used in

agriculture sector of developing countries. The results of the experiment in each

case were compared with baseline data of mineral diesel. Significant improvements

have been observed in the performance parameters of the engine as well as exhaust

emission, when lower blends of Karanja oil were used with preheating and also

without preheating. The gaseous emission of oxide of nitrogen from all blends with

and without preheating are lower than mineral diesel at all engine loads.

Venkanna et al (2009) reported the use of honge oil and diesel fuel blend in

direct injection diesel engine with increased injection opening pressure. The

performance, emission and combustion parameters of 20% honge oil and 80%

diesel fuel (volume basis) were found very close to neat diesel fuel where as higher

blend ratios were found inferior compared to neat diesel fuel. Improved premixed

heat release rate were noticed with 30% honge oil and 70% diesel fuel when the

injection opening pressure is enhanced. Performance and emission with 30% honge

oil and 70% diesel fuel are even better than neat diesel fuel at enhanced injection

opening pressure.

Purushothaman (2009) has experimentally investigated the effect of injection

pressure on the combustion process and exhaust emission of a direct injection diesel

41

engine fuelled with orange skin powder diesel solution . Earlier investigation by the

authors revealed that 30% orange skin powder diesel solution was optimum for

better performance and emission. In the present investigation the injection pressure

was varied with 30%orange skin powder diesel solution and the combustion,

performance and emission characteristics were compared with those of diesel fuel.

The different injection pressures studied were 215, 235 and 255 bar. The results

showed that the cylinder pressure with 30% orange skin powder diesel solution at

235 bar fuel injection pressure, was higher than that of diesel fuel as well as at other

injection pressures. Similarly, the ignition delay was longer and with shorter

combustion duration with 30% orange skin powder diesel solution at 235 bar

injection pressure. The brake thermal efficiency was better at 235 bar than that of

other fuel injection pressures with orange skin powder diesel solution and lower

than that of diesel fuel. The orange skin powder diesel solution emission with 30%

orange skin powder diesel solution was higher at 235 bar. The hydrocarbon and

carbon emission were lower with 30% orange skin powder diesel solution at 235

bar. The smoke emission with 30% OSPDS was marginally lower at 235 bar and

marginally higher at 215 bar than for diesel fuel. The combustion, performance and

emission characteristics of the engine operating on the test fuels at 235 bar injection

pressure were better than other injection pressures.

Baiju et al (2009) investigates the scope of utilizing biodiesel developed

from both through the methyl as well as ethyl alcohol route (methyl and ethyl ester)

from Karanja oil as an alternative diesel fuel. The major problem of using neat

Karanja oil as a fuel in a compression ignition engine arises due to its very high

viscosity. Trans-esterification with alcohols reduces the viscosity of the oil and

other properties have been evaluated to be comparable with those of diesel. In the

present work, methyl and ethyl esters of Karanja oil were prepared by trans-

esterification using both methanol and ethanol. The physical and chemical

properties of ethyl esters were comparable with that of methyl esters. However,

viscosity of ethyl esters was slightly higher than that of methyl esters. Cold flow

42

properties of ethyl esters were better than those of methyl esters. Performance and

exhaust emission characteristics of the engine were determined using petrodiesel as

the baseline fuel and several blends of diesel and biodiesel as test fuels. Results

show that methyl esters produced slightly higher power than ethyl esters. Exhaust

emission of both esters were almost identical.

Bajpai et al (2009) performed the experimental investigation for performance

and emission characteristics of diesel and karanja oil fuel blends (5%, 10%, 15%

and 20%) in a single cylinder direct injection constant speed compression ignition

engine at varying loads (0%, 20%, 40%, 60%, 80%, and 100%) Their results

showed that a fuel blend of 10% karanja oil showed higher BTE at a 60% load. The

overall emission characteristics were found to be best for the case of 10% of karanja

oil over the entire range of engine operation.

Pandian et al (2011) reported the effect of injection system parameters such

as injection pressure, injection timing and nozzle tip protrusion on the performance

and emission characteristics of a twin cylinder water cooled naturally aspirated

direct injection compression ignition engine. Biodiesel, derived from pongamia

seeds through trans-esterification process, blended with diesel was used as fuel in

this work. The experiments were designed using a statistical tool known as Design

of Experiments based on response surface methodology. The resultant models of the

response surface methodology were helpful to predict the response parameters such

as SEC, BTE, CO, HC, smoke opacity and NOX and further to identify the

significant interactions between the input factors on the responses. The results

depicted that the SEC, CO, HC and smoke opacity were lesser, and BTE and NOX

were higher at 2.5 mm nozzle tip protrusion, 225 bar of injection pressure and at

30° BTDC of injection timing. Optimization of injection system parameters was

performed using the desirability approach of the response surface methodology for

better performance and lower NOX emission. An injection pressure of 225 bar,

injection timing of 21° BTDC and 2.5 mm nozzle tip protrusion were found to be

43

optimal values for the pongamia biodiesel blended diesel fuel operation in the test

engine of 7.5 kW at 1500 rpm.

2.16 PERFORMANCE UNDER DIFFERENT COMPRESSION RATIO

Craig McLanahan et al (2005) proposed the concept of variable compression

promises improved piston engine performance, efficiency, and emission, but

commercial implementation has not been successful due to the complex geometries

needed to implement it. With a suitable design, variable compression could improve

fuel efficiencies, starting, and partial load performance, among other characteristics.

Compression ratio is the key to efficiency of reciprocating engines. The efficiency

of a compressed air cycle is solely dependent on compression ratio for ideal four-

stroke engine processes; efficiency is almost completely dependent upon

compression and fuel/air ratio (mixture).

Raheman (2008) has experimentally investigated the mahua oil biodiesel

(B100), diesel fuel and their blends (B20,B40, B60, and B80) in a single cylinder

four stroke diesel engine by varying compression ratio(18:1 20:1),injection timing

(35 45° BTDC). They found that biodiesel could be blended with diesel fuel up to

20% at any of the compression ratio and injection timing tested for getting nearly

same performance as that with diesel.

Ratnakara Rao et al (2008) proposed that, in order to find out optimum

compression ratio experiments were carried out 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 14.8 showed a drop in break

thermal efficiency, rise in fuel consumption along with increased smoke densities.

44

Anand et al (2009) reported the tests conducted in a single cylinder variable

compression ratio diesel engine at a constant speed of 1500 rpm. Highest brake

thermal efficiency and lowest specific fuel consumption were observed for 5%

biodiesel blend for compression ratio of 15 and 17 and 20% biodiesel blend for

compression ratio of 19. The 20% biodiesel blend at a compression ratio of 17 had

maximum nitric oxide emission as 205 ppm, while it was 155 ppm for diesel.

Substantial reduction in Carbon monoxide emission and smoke in the full range of

compression ratio and loads was observed.

Jindal et al (2010) investigated experimentally the effect of compression

ratio and injection pressure on performance and emission characteristics in direct

injection compression ignition engine running on jatropha oil biodiesel. Increase in

compression ratio associated with increase in injection pressure improves the

performance of the engine. Increase in compression ratio leads to increase in

emission of HC and exhaust temperature whereas smoke and CO emission reduces.

NO emission are found to remain unaffected at higher injection pressure. Therefore,

they concluded that for fuelling the engine with jatropha oil biodiesel, one should

go for higher compression ratio associated with higher injection pressure.

Muralidharan (2011) reported the performance, emission and combustion

characteristics of a single cylinder four stroke variable compression ratio multi fuel

engine when fueled with waste cooking oil methyl ester and its 20%, 40%, 60% and

80% blends with diesel (on a volume basis) are investigated and compared with

standard diesel. The suitability of waste cooking oil methyl ester as a biofuel has

been established in this study. Bio diesel produced from waste sun flower oil by

trans-esterification process has been used in this study. Experiment has been

conducted at a fixed engine speed of 1500 rpm, 50% load and at compression ratios

of 18:1, 19:1, 20:1, 21:1 and 22:1. The impact of compression ratio on fuel

consumption, combustion pressure and exhaust gas emission has been investigated

and presented. Optimum compression ratio which gives best performance has been

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identified. The results indicate longer ignition delay, maximum rate of pressure rise,

lower heat release rate and higher mass fraction burnt at higher compression ratio

for waste cooking oil methyl ester when compared to that of diesel. The brake

thermal efficiency at 50% load for waste cooking oil methyl ester blends and diesel

has been calculated and the blend B40 is found to give maximum thermal

efficiency. The blends when used as fuel results in reduction of carbon monoxide,

hydrocarbon and increase in nitrogen oxides emission.

2.17 BIODIESEL EMISSION IN CI ENGINES

Babu (2003) reported the review work on the performance and emission

characteristics of neat vegetable oil, biodiesel, and its blends in compression

ignition engine. Their results show that compared to No. 2 diesel fuel, all of the

vegetable oils are much more viscous, are much more reactive to oxygen, and has

higher cloud point and pour point. They also found that compared with diesel fuel,

vegetable oils and their biodiesels offer lower engine noise, and lower smoke, HC,

and CO, slightly higher NOx and higher thermal efficiency. In addition, 25/75 blend

of vegetable oil with diesel fuel, 20/80 blend of biodiesel with diesel fuel offers

better engine performance and lower emission. However, they had concentrated

mainly on the study of the performance and emission characteristics for edible

vegetable oils and its derivatives.

Mandepe et al (2005) introduced the common rail direct injection diesel

engine to determine the effects of jatropha oil biodiesel on performance and

emission characteristics. They found that HC and NOx emission are compatible to

that of fossil diesel fuel. However, CO emission tend to increase and PM emission

were significantly lower than those of diesel fuel.

Demirbas (2009) reported the progress and recent trends in biodiesel fuels.

He concluded that the edible oils in use at that time were soybean, sunflower,

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rapeseed and palm and the non-edible oil used as feedstock for biodiesel production

includes jatropha, karanja, mahua, polanga, neem, rubber seed, silk cotton tree,

waste cooking oil and microalgae, etc. The main advantages of biodiesel include its

imported petroleum, biodegradability, high flash point, and inherent lubricity in the

neat form. The main disadvantages of biodiesel are its higher viscosity, lower

energy content, higher cloud point and pour point, lower engine speed and power,

injector coking, engine compatibility, and high price. Blends of up to 20% biodiesel

mixed with petroleum diesel fuels can be used in nearly all diesel equipment and are

compatible with most storage and distribution equipment. Neat biodiesel and

biodiesel blends reduce PM, HC and CO emission and slightly increase NOx

emission compared with petroleum-based diesel fuel used in an unmodified diesel

engine.

2.18 TEAR DOWN ANALYSIS FOR BIODIESEL

Fraer (1996) reported that Mack MR 688p model vehicle having six

cylinders its compression ratio of 16.5:1 and producing the power 300 hp at

1950 rpm used in postal purposes. The engine and fuel system components were

disassembled, inspected and evaluated to compare wear characteristics after 4 years

of operation and more than 6,00,000 miles accumulation on B 20 no difference in

wear or other issues were noted during the engine teardown. The cylinder heads of

B20 engines contained a heavy amount of sludge around the rocker assemblies that

was not found in the diesel engines. The sludge contained high levels of sodium

possibly caused by accumulation of soaps in the engine oil. The B20 engines

required injector nozzle replacement over the evaluation and teardown period this is

due to out of specification of fuel. The biological contaminants may have causes the

filter plugging.

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Teerapong Baitiang et al (2008) reported the effects of neat biodiesel (B100)

and pure jatropha oil on engine performance, black smoke density, fuel

consumption and durability of engines. Two 14-horse power, single cylinder diesel

engines were dedicated for the experiment using those fuels. It is noticeable that

black smoke measured from the engines using both biodiesel and jatropha oil can be

hugely reduced. However, in the case of field test when each engine was connected

to power water pumps in order to determine the long term effects, the engine that

was fueled with jatropha oil presented some problems. The injector and fuel filter

were clogged enough to cause engine malfunction. The parts were then replaced and

petroleum diesel fuel was added at anincrement of 20% in the blended fuel to

reduce the concentration of jatropha oil until the engine could run continuously

again. It was found that the highest amount of jatropha oil could be used was a

blend between jatropha oil and diesel fuel of 60:40 by volume for practical running

time before failure. In the case of the engine using biodiesel, the field test could be

performed without any engine problem for over 500 hours.

Basinger et al (2010) reported the 500 hour test with waste vegetable oil fuel.

The engine break-in period was identified as taking between 200 and 300 h.

Emission analysis supported the break-in definition as smoke opacity and carbon

monoxide values fell from 9% and 600 ppm (respectively) during the first few

hundred hours, to 5% and 400 ppm in the final 200 h. Lubrication oil viscosity was

found to be the limiting degradation factor in the lube oil, requiring oil to be

changed every 110 h. Piston ring mass loss was found to correlate very closely with

chromium buildup in the lubrication oil and the mathematical model that was

developed was used to estimate that piston ring inspection and replacement should

occur after 1000 h. Cylinder vocalization was found to be most sever at top dead

center (TDC) at 53 microns of averaged increased diameter.

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2.19 SUMMARY OF THE LITERATURE REVIEW

From the above literature review, the following preliminary conclusions are

arrived and technical facts based on these conclusions are incorporated in this

research work. The important conclusions are:

Biodiesel is an alternative fuel for diesel engines.

Raw oils are not suitable for diesel engines.

The applications of ester of vegetable oils as diesel engine fuels are suitable.

Trans-esterification is the best way for reducing viscosities from the raw oils.

Methyl esters of vegetable oils are preferred than the ethyl esters of

vegetable oils.

The performance of the biodiesel operated engine is lower than the diesel

fuel.

Advancing or retarding the injection timings, compression ratios and

injection pressures are the best ways for improving the efficiency and

reducing the emissions for biodiesel.

From the foregone discussion in this literature review, it is evident that more

work is needed to optimize the injection timings, compression ratios and injection

pressures for biodiesel.