17

CHAPTER 2

LITERATURE SURVEY

2.1 INTRODUCTION

The engine input parameters and biodiesels play a vital role in

determining the performances of the compression ignition engine. The engine

performances can be defined in terms of input parameters such as brake

power, load, and compression ratio and fuels quality. Also, the engine

performance can be defined as combustion and emission characteristics.

Generally, in CI engine the diesel fuel is ignited at the end of compression.

The compression ratio of CI engine is 14:1 to 22:1 and for diesel engine the

combustion takes place at high compression ratios only. Moreover in methyl

ester based biodiesel the combustion takes place at a high compression ratio.

The review was classified according to the output features of the

fuels used in CI engines as below

1. Studies using biodiesel as fuel;

2. Preheated oil blends;

3. Methyl esters of edible, non-edible and cooking oil as fuel;

4. Varying compression ratios;

5. Artificial neural network.

6. Biodiesel Research – Recent Studies

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2.2 STUDIES USING BIODIESEL AS FUEL

The present study focuses on the selection of edible and non-edible

vegetable oil, biodiesel preparation of suitable selected oil, measuring

properties as per ASTM D 6751 biodiesel standards and experimental testing

based on input and output parameters. These test results are compared with

PBDF. The literature survey of this research is categorized based on biodiesel

production methods, combustion, emissions and performance characteristics.

The reports for the above are studied from 1992 to 2012. The literature survey

also gives collective information about various methodologies employed for

conducting experiments based on the input and output parameters of the

engine.

Carraretto et al. (2004) investigated the potentialities of biodiesel as

an alternative fuel based on strategic considerations and field experiences in

diesel engines.

Burnwal and Sharma (2005) reviewed the work done on biodiesel

production and utilization, resources available, processes developed and

barriers to the use of biodiesel in India. The increasing import bill has

necessitated the search for liquid fuels as an alternative to diesel, which is

being used in large quantities in transport, agriculture, industrial, commercial

and domestic sectors. Biodiesel obtained from vegetable oils has been

considered as a promising option of the future India.

Sharma et al. (2008) clearly illustrated the advancements in

development and characterization of biodiesel. The main advantage in its

usage is attributed to lesser exhaust emissions in terms of carbon-monoxide,

hydrocarbons, particulate matter, polycyclic aromatic hydrocarbon

19

compounds and nitrated polycyclic aromatic hydrocarbon compounds.

Transesterification is the process successfully employed at present to reduce

the viscosity of biodiesel and improve other characteristics.

Demirbas (2008) reviewed the recent trends in biodiesel fuels that

are used in diesel engine. The edible oil used in diesel engine at present is

soyabean, sunflower, rapeseed and palm. The inedible oil used as feedstock

for biodiesel production includes J. curcas, M. indica, F. elastica, A. indica, C.

inophyllum jatropha, neem, P. pinnata, rubber seed, mahua, silk cotton tree,

cooking waste, microalgae, etc. Biodiesel has more advantages than diesel

fuel due to its less polluting nature and because it is a renewable energy

resource. It is also an environmentally-friendly fuel that can be used in any

diesel engine without modification.

Basha et al. (2009) observed the 350 oil-bearing crops out of these

few are potential biodiesel like sunflower, rapeseed, palm and jatropha. It is

observed that biodiesel has similar combustion characteristics as diesel and

also found that the base catalyst performs better than acid catalyst and

enzymes. The tests with refined oil blends indicated considerable

improvement in performance.

Jain and Sharma (2009) preamble the stability of biodiesel and its

blends for different types of the fuel stabilities, mechanism of occurrence and

correlations/equations developed to investigate the impact of various stability

parameters on the stability of the fuel. On the other hand the authors

suggested that number of researches are required to investigate the effect of

stability of biodiesel on engine performance as well as effect on emissions.

Singh and Singh (2009) validated the biodiesel production through

the use of different sources and characterization of oils and their esters as a

20

substitute for diesel. The cost reduction technique and usage of waste land for

high yielding biodiesel production were discussed in the paper.

Balat and Balat (2010) reviewed the vegetable oils being

substituted for diesel engine due to the increase in petroleum prices and

petroleum availability. Also, the advantages of biodiesel over diesel fuel are

its portability, ready availability, renewability, higher combustion efficiency,

lower sulphur and aromatic content, higher cetane number, higher

biodegradability, better emission profile, safer handling, besides being

non-toxic.

Sidibe et al. (2010) evolved the use of crude filtered vegetable oil

as a fuel in diesel engines which also focused on the impact of the physical-

chemical characteristics of fuel SVOs, impact of production parameters on

SVO quality, and lastly, two types of SVO use in diesel engines: dual fueling

and blending.

2.2.1 Literature Summary for Biodiesel as Fuel

The summary of the literature review about biodiesel used in

compression ignition engine with various input and output parameters

1. The researchers mainly focused for potential of availability

biodiesel feedstock in India and also availability of waste land

usages in India.

2. From the observation of above literature review, higher

percentage of biodiesel blends with diesel is directly used in

the diesel engine with certain specifications for long term

operation.

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3. Another observation of the review is that the mode of engine

operation is used to identify with biodiesel as compared to

diesel.

4. Method of the biodiesel conversion process is identified

through the above literature.

From the literature review, it can be inferred that

1. Numerous works have been carried out on the use

compression ignition engines to study the different type of

experimental methods. These experimental methods are load,

speed and compression ratio, mean effective pressure etc.,

2. Most of the researchers used for higher standard compression

ratio with different loads and speed.

Hence, the present work is carried out for different compression

ratios with full-load and at a constant speed of operation with computerized

variable compression ratio and Multifuel engine.

2.3 PRE-HEATED OIL BLENDS

There has been plenty of research done so far on performance and

emissions testing with vegetable oil. It is possible to use unmodified vegetable

oils as ideal fuel for diesel engines with certain limitations. Straight vegetable

oil (SVO) is an effective fuel for many applications and has been in use in

different parts of the world for many years. However, practical results vary,

depending on the type and condition of the vegetable oil, engine, and fuel

system. Although fuel injection system is specially designed for petroleum

diesel, similar results can be found if the viscosity of the oil is lowered to

nearly that of diesel. This is typically accomplished by heating the SVO to a

22

relatively high temperature (about 700 to 90 0C). Research in the area of

biodiesel has shifted towards making it more economically feasible by

lowering production costs and increasing the energetic yields from various

feed stocks. Where the research has been lacking is in relation to the better

characterization of the performance of these fuels at various compression

ratios and the method of biodiesel production.

The present work brings about the performance, combustion and

emission of the engine at lower blending ratios of pre-heated palm oil as fuel.

The direct effects of compression ratio, blending ratio and load can clearly

give out the optimum values for operation. The 2D excels graph plots for each

performance data will provide us the data on the optimum operating range of

the engine. As a lower blending ratio is chosen, testing may also be feasible in

commercial engines. The performance of the engine will decide the suitability

of the oil blends in commercial engines. If the performance of the engine

seems to be better with vegetable oil blends rather than diesel, then the

problems of fuel injection and carbon buildup should be studied. By

overcoming the above-mentioned problems by some specialized design and

materials, vegetable oil blends can be commercialized.

Most of the researchers have studied the preheating of inlet fuel

reduces viscosity and can be implemented as indicated by the many results as

follows.

Bari et al. (2002) studied the effect of preheating the raw palm oil

on injection system, performance and emissions of a diesel engine. It was

reported that usage of preheating of crude palm oil up to 90 ºC leads to the

reduction of viscosity, enhancing smooth flow and also avoided fuel filter

clogging. During the experimental testing the injection system of testing

engine was not affected by using raw palm oil.

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Ramadhas et al. (2004) reviewed the use of straight vegetable oils

used in the engine which leads to various problems like fuel filter clogging,

poor atomization, and incomplete combustion as it is reported to be highly

viscous, dense, and poor non-volatility. The use of vegetable oils as IC engine

fuels can play a vital role in helping the developing world to reduce the

environmental impact of fossil fuels.

Pramanik et al. (2003) discussed the testing of diesel engines with

vegetable oils as diesel blend over preheating, which improved the

performance and reduced the emission, comparatively. Also, it reduced the

filter clogging and ensured smooth flow of oil.

Senthil Kumar et al. (2005) studied the use of pre-heated animal fat

as fuel in a compression ignition engine and experiments were conducted at

the fuel inlet temperatures of 30, 40, 50, 60 and 70 °C. The results indicated

that the combustion characteristics of animal fat are close to diesel and

emissions are lower than diesel.

Pugazhvadivu and Jayachandran (2005) asserted that the waste

frying oil can be pre-heated up to 135 º C and could be used as a diesel fuel

substitute for short-term engine operation. They reported an improvement in

the engine performance and a reduction in carbon-monoxide (CO) and smoke

level with the waste frying oil.

Agarwal (2007) noted that biodiesel operates in compression

ignition engine, and essentially requires 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. This

review focuses on performance and emission of biodiesel in CI engines,

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combustion analysis, wear performance on long-term engine usage, and

economic feasibility.

Agarwal and Agarwal (2007) detailed the effect of reducing

Jatropha oil’s viscosity by increasing the fuel temperature (using waste heat

of the exhaust gases) and thereby eliminating its effect on combustion and

emission characteristics of the engine. Experiments were conducted using

various blends of Jatropha oil with mineral diesel to study the effect of

reduced blend viscosity on emissions and performance of diesel engines.

Also, the performance and emission parameters were found to be very close

to mineral diesel for lower blend concentrations. However, for higher blend

concentrations, performance and emissions were observed to be marginally

inferior.

Alptekin and Canakci (2008) indicate that density and kinematic

viscosity are the parameters required by biodiesel and diesel fuel standards

because they are key fuel properties for diesel engines.

Agarwal and Rajamanoharan (2008) supervised the performance

and emission characteristics of a compression ignition engine fuelled by

Karanja oil and its blends (10%, 20%, 50% and 75%) with diesel. The results,

showed the performance parameters of the engine as well as exhaust

emissions, when lower blends of Karanja oil were used with and without

preheating. Karanja oil blends with diesel (up to 50% v/v) without preheating

as well as with preheating can replace diesel for operating the CI engines

giving lower emissions and improved engine performance.

Biona and Licauco. (2008) investigated the performance of a

compression ignition engine fueled with pre-heated waste cooking oil.

Preheated waste cooking oil has a good potential as a substitute for diesel

25

fuel. Also, the results indicated minimal reduction in power with an average

power drop of 5.8% relative to diesel fuel.

Karabektas et al. (2008) clearly explained the preheating of cotton

seed oil methyl ester in four different temperatures in order to reduce its

viscosity. The test data were used for evaluating the brake power and brake

thermal efficiency (BTE) together with CO and Nox emissions. The results

suggest that cottonseed oil methyl ester was pre-heated up to 90 ºC and then

can be used as a substitute for diesel fuel without any significant modification

at the expense of increased Nox emissions.

Hossain and Davies (2009) illustrated the number of plant oils can

be used satisfactorily in CI engines, without transesterification, by preheating

the oil and/or modifying the engine parameters and the maintenance schedule.

As regards life-cycle energy and greenhouse gas emission analyses, 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.

Sharma (2009) pre-heated karajana – diesel blend as fuel in finding

the optimal injection timing and pressure in CI engine. Injection pressure of

170 bar was found to be the optimum, as the highest brake thermal efficiency

and the lowest brake specific fuel consumption was observed. Slightly higher

smoke emissions were observed with B40 over the entire load range mainly

due to poor atomization of karajana oil. The effect of different injection

timing and injection pressure on smoke is not very significant.

Prasad (2009) validated that the heating temperature of the blends

increased with the increase in percentage of neat castor oil with diesel ranging

from 70 -120 ºC before entering into combustion chamber. These results were

26

compared to that of pure diesel and it was observed that the performance

characteristics were reduced and emission characteristics were increased

compared to that of diesel and it is due to lower calorific value, high viscosity

and delayed combustion process.

Ozsezen et al. (2009) utilized pre-heated crude sunflower oil

(PCSO) and tested it for combustion and emission properties against PBDF.

The cylinder gas pressure and heat release curves for PCSO at 75 ºC were

similar to those of PBDF. The ignition delays for the PCSO were longer and

the start of injection timing was earlier than for PBDF. The brake specific fuel

consumption increased than PBDF.

Hazar and Aydin (2010) used raw rapeseed oil blended with diesel

fuel of grade O50 and O20. The effects of fuel preheating to 100 ºC on the

engine performance and emission characteristics of a CI engine fueled with

rapeseed oil diesel blends were clarified. Heating is necessary for smooth

flow and to avoid fuel filter clogging. It can be achieved by heating RRO to

100 0C. It is concluded that preheating of the fuel have some positive effects

on engine performance and emissions when operating with vegetable oil.

Ingle et al. (2011) compared the performance of neat and pre-

heated trans-esterified cottonseed oil with diesel at various temperatures such

as 50, 70 and 90oC and the properties such as viscosity, flash point and pour

point were experimentally measured. The results revealed that preheating

cotton seed oil methyl ester up to 90oC at higher load led to increase in brake

thermal efficiency compared to diesel and brake specific fuel consumption

which increases at higher load as compared to diesel.

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2.3.1 Summary for Pre-heated Oil Blends

From the literature it can be inferred that

1. The vegetable oil is pre-heated in low viscous oil compatible

to blend with diesel for lower percentage on a volume basis in

order to avoid fuel filters chocking and poor atomization.

2 A thorough insight of literature review reveals that lower

percentage of pre-heated oil blends with diesel is directly used

in the diesel engine for long-term operation.

3. Also, the cost of lower percentage of pre-heated oil used in a

diesel engine is not much varied compared to diesel.

4. The review reveals that engine output parameters such as

performance and combustion results of pre-heated oils are

similar to diesel, and the emission results are lower than

diesel.

In this present work, crude palm oil is identified as pre-heated in

low viscous oil compatible to blend with diesel and the following proportions

of blends are chosen – O5, O10, O15, and O20. The different blends of the

above chosen PHPO are prepared and the following investigations are carried

out.

The combustion characteristics such as heat release rate,

ignition delay and combustion pressure are observed with

reference to the crank angle for various blends of different

compression ratios at full-load conditions. Also, it was

compared with the result of standard diesel fuel.

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The performance characteristics such as brake thermal

efficiency, specific fuel consumption and exhaust gas

temperature of a variable compression ratio engine operated

at different blends for different compression ratios like 17:1,

18:1 and 19:1 and for full-load is compared with the observed

results of standard diesel fuel.

Simultaneously, the emission characteristics such as CO, CO2,

HC, NOx and smoke are investigated with reference to the

results of petroleum based diesel fuel.

2.4 METHYL ESTERS OF EDIBLE, NON-EDIBLE AND

COOKING OILS

The importance of vegetable oil based methyl ester is already

explained in chapter 1.4. In this research, the method of transesterification is

used to convert vegetable oil into biodiesel. Palm oil (from the African oil

palm, Elaeis guineensis) has long been recognized in West African countries.

Palm oil, like other vegetable oils, can be used to create biodiesel, as either a

simply processed palm oil mixed with PBDF, or processed through

transesterification to create a palm oil methyl ester blend, which meets the

international ASTM D 6751 and EN 14214 specifications. Biofuels from

palm oil are taking on renewed global importance as countries seek to

substitute the soaring price of conventional oil and also cut hazardous

emissions. Palm oil has global importance due to its yield per hectare and the

price in comparison with other edible oils. Considering the price of palm oil,

it is the lowest priced edible oil that has tremendous potential to replace

petroleum diesel. The rise in the price of palm oil is quite normal compared to

that of soybean, groundnut, coconut and rapeseed.

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A commercially-chosen vegetable oil viz. Corn oil is generally less

expensive than most other types of vegetable oils. One bushel of corn

contains 1.55 pounds of corn oil (2.8% by weight). Corn oil is also a

feedstock used for biodiesel. Refined corn oil is 99% triglyceride, with

proportions of approximately 55% polyunsaturated fatty acids, 30%

monounsaturated fatty acids, and 15% saturated fatty acid. Of the saturated

fatty acids, 80% are palmitic acid, 14% Stearic acid, and 3% arachidic acid.

Over 99% of the monounsaturated fatty acids are oleic acid.

In recent years, systematic efforts have been made by several

researchers (Rakopoulos et al. 1992; Humke et al. 1995; Barsic et al. 1996;

Hemmer Lien et al. 1997; Michel et al. 1998; Vellguth et al. 1998; Reddy

2000; Agarwal et al. 2001; Altin et al. 2001; Herchel et al. 2001; De Almedia

et al. 2002) to use vegetable oils such as sunflower, safflower, peanut oil,

soybean oil, rapeseed oil, rice bran oil, Jatropha, pongamia, coconut oil, etc.

and their derivatives, in the place of diesel in CI engines and proved useful as

alternate fuel. Most researchers have studied the methyl ester based biodiesels

and it is used to reduce viscosity and can be implemented as indicated by the

many results as follows.

Heywood (1998) presented an overview of diesel engine

combustion characteristics like heat release rate, ignition delay period and

combustion pressure. Also, it is used to find out the better combustion results

of biodiesel.

Graboski et al. (1998) and Igwe (2004) studied the straight

vegetable oils used in the engine which leads to various problems like fuel

filter clocking, poor atomization and incomplete combustion because of its

highly viscosity, high density and poor non-volatility. In order to reduce the

viscosity of the straight vegetable oil the following four techniques were

30

adopted; namely heating/pyrolysis, dilution/blending, micro-emulsion, and

transesterification. Among all these techniques transesterification is an

extensive, convenient and the most promising method for the reduction of

viscosity and density of the straight vegetable oils. However, this adds extra

cost of processing because the transesterification reaction involving chemical

and process heat inputs.

Recep et al. (2001) found that both straight vegetable oil (svo) and

methyl ester are promising alternative fuels for diesel engines. The properties

of SVO and its methyl ester were studied. SVO used in engine still have

problems, such as flow, atomization and heavy particulate emissions.

Ajiwe et al. (2003) performed the palm oil methyl ester and ester-

diesel blends comparatively with diesel for their fuel properties that will make

them serve as alternatives to diesel in diesel engines. The results of this study

have confirmed that methyl ester and ester-diesel blends of palm oil could be

utilized in place of diesel in diesel engines. The use of methyl esters, and

blends would certainly reduce pollution of the environment by ordinary fossil

diesel, would help boost agriculture and would help conserve the fossil fuel.

Sharma et al. (2005) investigated on the various aspects of engine

performance using a neem - diesel blend (B-20) as fuel through extensive

experimentation at different injection pressure. Significant reduction in

emissions was observed as compared to that of pure diesel.

Demirbas (2005) studied the transesterification processes using low

molecular weight alcohols. A mixture of mono alkyl esters of fatty acids and

glycerol was obtained as a result of the reaction. Glycerol, having high

viscosity, must be removed from the reaction product. The most popular

method of biodiesel production is the transesterification technique because the

31

transesterification of triglycerides by methanol, ethanol, propanol and

butanol, has proved to be the most promising process. Methanol is the

commonly used alcohol in this process, due in part to its low cost. Methyl

esters of vegetable oils have several outstanding advantages among other new

renewable and clean engine fuel alternatives.

Agarwal et al. (2006) observed the performance and emission

characteristics of linseed oil, mahua oil, rice bran oil and linseed oil methyl

ester (LOME), in a stationary single cylinder, four stroke diesel engines and

compared it with mineral diesel. Straight vegetable oils posed operational and

durability problems when subjected to long-term usage in CI engine. These

problems were attributed to high viscosity, low volatility and polyunsaturated

character of vegetable oils. However, these problems were not observed for

LOME blends. Hence, the process of transesterification is found to be an

effective method of reducing vegetable oil viscosity and eliminating

operational and durability problems. Economic analysis was also done in this

study and it was found that the use of vegetable oil and its derivative as diesel

fuel substitutes has almost similar cost as that of mineral diesel.

Murugasen et al. (2007) reviewed the prospects and opportunities

of introducing vegetable oils and their derivatives as fuel in diesel engines.

Optimization of alkali-catalyzed transesterification of pongamia pinnata oil

for the production biodiesel is discussed. Use of biodiesel in a conventional

diesel engine results in substantial reduction in unburned hydrocarbon

(UBHC), carbon-monoxide (CO), particulate matters (PM) emission and

oxide of nitrogen. The suitability of injection timing for diesel engine

operation with vegetable oils and its blends, environmental considerations are

discussed.

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Balusamy et al. (2007) examined the engine performance with the

biodiesel of thevetia puruviana which was comparable to that of diesel.CO,

HC emissions were less but Nox and smoke were slightly higher than that of

diesel. In this research, DEE was added in the ratios of 5%, 10%, 15% and

20% of the thevetia peruviana biodiesel to reduce the Nox and smoke

simultaneously and the optimum blending ratios were found out.

Benjumea et al. (2008) illustrated the blends of biodiesel prepared

on a volume basis. The fuel properties such as density and viscosity of the

blends were measured by following ASTM test methods. From this study, the

density and viscosity of the blends increased with the increase of biodiesel

concentrations in the fuel blend.

Narvaez et al. (2008) detailed the physical and transport properties

of palm oil and its methyl esters. Melting ranges, boiling points and

combustion heats of palm oil and of its methyl esters was measured,

experimental values of the density, viscosity, and heat capacity of palm oil, of

its methyl esters and of some mixtures of them were determined, as a function

of temperature.

Banapurmath (2008) exemplified the effort to evaluate feasibility of

popular alternative fuels in the form of oil/honge oil methyl ester and

producer gas as a total replacement for fossil fuels. The performance,

emission and combustion characteristics of the engine in dual fuel mode

under variable load conditions have been compared at their optimum injection

timings with honge oil, HOME and diesel as injected fuels and producer as

inducted fuel.

Suresh Kumar et al. (2009) investigated the blends of PPME and

diesel and asserted that they could be successfully used with acceptable

33

performance and better emissions than pure diesel up to a certain extent. From

the experimental investigation, it was concluded that blends of PPME with

diesel up to 40% by volume (B40) could replace the diesel for diesel engine

applications for obtaining less emissions and better performance.

Lakshmanan (2009); Demirbas (2009); Lin Lin et al. (2011)

observed that biodiesel is a non-toxic, biodegradable and renewable fuel with

the potential to reduce engine exhaust emissions. The main disadvantages are

higher viscosity, lower energy content, higher cloud point and pour point. An

overview was given on possible environmental and social impacts associated

with biodiesel production, such as food security, land change and water

source.

Basha et al. (2009) investigated the combustion characteristics of

biodiesel and noted that they are similar to diesel. Biodiesel and its blends

were found to have a shorter ignition delay, higher ignition temperature, and

higher ignition pressure and peak heat release. The engine power output was

found to be equivalent to that of diesel fuel.

Murali Krishna and Mallikarjuna (2009) revealed that the blended

fuel can be used straight away in CI engines without any modifications to the

engine as the result showed better performance and improved emission

compared to diesel fuels tested for the entire range of engine operation.

Prasad et al. (2009) conducted experimentation on a single cylinder

diesel engine with mahua methyl ester (MME) in the neat form along with the

cooled EGR and performance, combustion pressure, and emission parameters.

These are collected by using suitable instrumentation. The Same

experimentation was repeated for the petroleum diesel and a comparison was

made to evaluate the applicability of MME along with EGR without major

modifications. After the analysis, it was concluded that 5% EGR is

34

recommendable with neat biodiesel (MME) run, and in most of the situations,

it proved its merit over neat diesel run.

Dobo visek et al. (2009) studied the influence of fuel properties of

mineral diesel, neat biodiesel and their blends on the engine characteristics

with the aim to reduce harmful emissions. The biodiesel has been produced

from rapeseed oil by using the engine without any modifications; biodiesel

has a positive effect on CO and smoke emissions and on exhaust gas

temperature at full-load conditions. The HC emission and SFCIs increased at

peak torque condition.

Baiju et al. (2009) examined the scope of utilizing biodiesel

developed from both methyl as well as ethyl esters from Karanja oil as an

alternative diesel fuel. Results showed that methyl esters produced slightly

higher power than ethyl esters. The exhaust emissions of both esters were

almost identical.

Venkanna and Venkataramana (2009) supervised the performance,

exhaust emission and combustion characteristics of the DI diesel engine,

typically used in the agricultural sector, over the entire load range when

fueled with rice bran oil and diesel fuel blends. It was reported that utilization

of vegetable oils as an alternative diesel engine fuel has resulted in higher

brake specific fuel consumption and emissions such as CO,HC and smoke

opacity. Compared to neat diesel fuel it was attributed to have lower heating

value, high viscosity, poor atomization, low volatility and unsaturated

characteristics of neat vegetable oils.

According to Buyukkaya (2010) experimental tests were conducted

to evaluate the performance, emission and combustion of a diesel engine

using neat rapeseed oil and its blends of 5%, 20% and 70%, and standard

diesel fuel separately. The results indicate that the use of biodiesel is lower

35

compared to. Also, from the combustion analysis, it was found that ignition

delay was shorter for neat rapeseed oil and its blends tested compared to that

of standard diesel. The combustion characteristics of rapeseed oil and its

diesel blends closely followed those of standard diesel.

Jain and Sharma (2010) showcased that the biodiesel consisted of

long chain fatty acid esters derived from feed stocks such as vegetable oils,

animal fats and used frying oil, etc. Oxidation of biodiesel can cause

degradation of fuel quality by affecting the stability parameters.

Boulifi et al. (2010) presented the storage life of biodiesel i.e., How

long biodiesel can be safely stored; is it desirable to have a measurement of

the stability of the biodiesel against oxidation. Storage time and oxygen

availability have been considered as possible factors influencing oxidative

instability. Biodiesel from corn oil was stored for a period of time, and the

physico-chemical parameters of the samples were measured at regular interval

of time.

Pandian et al. (2010) investigated the pongamia biodiesel–diesel

blend fuel in CI engines with EGR and DMC, They have found that it

showcased reduced smoke and nitric oxide (NOx) emission and carbon-

monoxide (CO) and hydrocarbon (HC) emissions. However, the addition of

DMC with EGR caused an increase in both brake specific fuel consumption

and brake thermal efficiency.

Aguledo et al. (2010) evaluated the engine performance, nitrogen

oxide emissions (NOx) and smoke opacity of a high speed direct injection

diesel engine fuelled with neat palm oil biodiesel (POB). Conventional diesel

fuel was taken at baseline or reference fuel. According to the experimental

results, POB fuelling reduced engine power output, increased fuel

consumption, slightly increased efficiency, always decreased smoke opacity,

36

and reduced or increased NOx emissions depending on the engine operation

mode.

Mirheidari et al. (2010) compared biodiesel as a renewable

alternative fuel for petroleum based diesel fuel and inferred that it produces

lower emissions of all types (CO, CO2, HC and PM) except nitrogen oxides

(NOx). Orthogonal Least Squares and neural network are the two system

identification techniques used in this paper. The results estimated from the

two identification methods are compared and illustrated that the designed

estimator is accurate in both cases.

Kannan et al. (2010) mentioned that the Diethyl Ether (DEE), an

oxygenated additive can be added to diesel/ biodiesel fuels to suppress the

NOx emission. From the detailed study, it was concluded that the blending

ratio of 20% gives better performance and lesser emissions than other

combinations.

Altun and Sugozu (2010) evaluated the performance and emission

characteristics of a diesel engine fueled with canola oil ethyl ester and diesel

fuel. The engine torque and power obtained in biodiesel were less, and the

specific fuel consumption was found to be higher, which could be attributed

to the lower calorific value of biodiesel. CO was decreased and NOX was

higher with the use of biodiesel.

Hazar et al. (2010) studied the corn oil methyl ester and its mixture

was used an alternative in diesel engines and tests were performed on

uncoated engines, and then repeated on a coated engine and the results were

compared. Low heat rejection (LHR) engines aim to do this by reducing the

heat lost to the coolant. The diesel engine with its combustion chamber walls

insulated by ceramics is referred to as LHR engine. Thermal barrier coatings

37

(TBC) are used to improve reliability and durability of hot section metal

components and enhance engine performance and efficiency in diesel engines.

Elango and Senthilkumar (2011) conducted experiments with

different blends of jatropha oil and diesel at various loads. The results

indicated that the brake thermal efficiency of diesel is higher at all loads and

specific fuel consumption is lower for blend B20. The emission result

revealed that HC, CO2 and CO is lesser than diesel at all loads of jatropha and

its blends.

Ozsezen and Canakci (2011) investigated the combustion and

performance characteristics of waste palm oil and canola oil methyl esters.

The results revealed that both methyl esters produced more nitrogen oxides

(NOx) emissions when compared with those of the PBDF over the speed

range. Also, the brake power is reduced and brake specific fuel consumption

is increased.

Celikten (2012) illustrated the performance and emission

characteristics of a diesel engine fueled with diesel, rapeseed oil and hazelnut

oil methyl ester blends. It was observed that maximum engine torque and the

lowest specific fuel consumption were obtained with diesel. B1 was the

nearest fuel to diesel with regard to engine torque and specific fuel

consumption.

Many studies have been carried out to evaluate the performance,

combustion and emission characteristics of diesel engines fueled with

biodiesel and its blends with diesel fuel. As many of them are edible, their

usage may create a shortage of oil seeds for daily food, which necessitates

identification of new kinds of non-edible vegetable oil.

38

As the food vs. fuel debate mounts, research is turning to biodiesel

production from waste. In Malaysia, an estimated 50,000 tonnes of used

frying oils, both vegetable oils and animal fats, are disposed of yearly without

treatment as wastes. In a 2006 study, researchers found that used frying oil,

after pre-treatment with silica gel, is a suitable feedstock for conversion to

methyl esters by catalytic reaction using sodium hydroxide. The methyl esters

produced have fuel properties comparable to those of petroleum diesel, and

can be used in unmodified diesel engines (Alkebulan resources.com).

Due to the above complications, present studies diverted to third

generation biofuel like waste cooking oils. In this study a special attention

was given by choosing waste cooking rice bran oil and waste cooking

cottonseed oil as fuel. The literature review was collected based on the above

feedback.

Zhang et al. (2003) studied the four different methods of biodiesel

production from waste cooking oil. Also, another advantage of biodiesel

production from waste cooking oil is to reduce the raw material cost. The

acid-catalyzed process using waste cooking oil proved to be technically

feasible with less complexity than the alkali-catalyzed process using waste

cooking oil, thereby making it a competitive alternative to commercial

biodiesel production by the alkali-catalyzed process.

Canakci (2007) checked for the availability and the properties of

restaurant waste oils and rendered animal fat as low-cost feedstocks for

biodiesel production. However, there are large amounts of restaurant waste

oils and rendered animal fats potentially available for biodiesel production. If

these oils are converted to biodiesel, it will directly reduce the cost of

biodiesel and will influence the biodiesel market. Due to the high level of

FFA in the waste restaurant oils and animal fats, transesterification cannot be

39

applied directly. It is necessary to reduce the FFA level of the oil by using an

acid catalyst process.

Kulkarni and Ajay (2006) reviewed the methods for the

transesterification of waste cooking oil and the performance of biodiesel

obtained from waste cooking oil in a commercial diesel engine. Also,

examines the basic chemistry involved during frying and the effects of the

products formed in the frying process on biodiesel quality.

Powell (2007) investigated the engine performance and emissions

of various fuel blends of cotton seed oil biodiesel. The objective of this

research was to determine the correlation between diesel engine performance

and the percentage of cottonseed oil biodiesel used in the fuel. The primary

indicator for comparison of fuel blends is brake specific fuel consumption

(Bsfc).

Kemp (2006) and Radich (2006) potrayed the use of used cooking

oil as feedstock which reduces biodiesel production cost by about 60– 70%

because the feedstock cost constitutes approximately 70–95% of the overall

biodiesel production cost. It was reported that the prices of biodiesel will be

reduced approximately to the half with the use of low cost feedstock.

Rao et al. (2008) analyzed the combustion, performance and

emission characteristics of used cooking oil methyl ester and its blends with

diesel oil. It was analyzed in a direct injection CI engine. The ignition delay

of used cooking oil methyl ester and its blends was found to be lesser as

compared to that of diesel. The peak pressure of used cooking oil methyl ester

-diesel is higher than that of diesel. The engine develops maximum rate of

pressure rise and maximum heat release rates for diesel compared to used

cooking oil methyl ester and its blends.

40

Enweremadu and Rutto (2010) reviewed the combustion, emission

and performance characteristics of used cooking oil biodiesel on diesel

engine. The observation of this review is that the engine performance of the

UCO biodiesel and its blends was only marginally lesser compared to diesel.

From the standpoint of emissions, NOx emissions were slightly higher while

un-burnt hydrocarbon emissions were lower for UCO biodiesel when

compared to diesel fuel. There were no noticeable differences between UCO

biodiesel and fresh oil biodiesel as their engine performances, combustion and

emission characteristics bear a close resemblance.

Arslan (2011) examined the emission characteristics of a diesel

engine using waste cooking oil as biodiesel fuel. The results of this study

revealed that WCO methyl esters have similar properties with diesel fuel, and

they support the statement that exhaust emissions from biodiesel fuels are

lower than those of fossil diesel fuels, which may indicate that biodiesel has

better effects on air quality.

Kumaran et al. (2011) exhibited the technical feasibility of

Langkawi waste cooking oil as fuel. The results revealed the quantity and

quality assessment of the above biodiesel and also physical and chemical

properties of the above oil were analyzed.

The performance and exhaust emissions of a DI diesel engine

fueled with waste cooking oil and inedible animal tallow methyl esters was

examined by Altun et al. (2010). The BSFCs for both biodiesel were higher

than that of diesel fuel, and also the BSFCs for both biodiesel were

comparable to each other.

Liu et al. (2012) examined the biodiesel produced from waste

cooking oil. The brake specific fuel consumption and the feasibility of

biodiesel blends were assessed. Using waste cooking oil biodiesel is an

41

economical source and an effective strategy for reducing cost, and solves the

problem of waste oil disposal.

Mohebbi et al. (2012) studied the waste cooking oil biodiesel used

in diesel engines. Results of brake thermal efficiency obtained with waste

cooking oil biodiesel is higher than that of diesel fuel when applying the same

EGR rate. Similarly, the reduction of engine torque and increase of BSFC is

lower with waste cooking oil biodiesel with respect to diesel fuel. Thus, EGR

has lower negative effect on engine performance in case of waste cooking oil

biodiesels compared to diesel fuel.

Goga et al. (2012) studied the performance of evaluation of

biodiesel from waste cooking oil as fuel. The experimental result revealed that

the biodiesel produced less smoke as compared to diesel on the same load and

gave the better performance as compared to diesel. Waste cooking oil can be

used in the place of diesel as a source of fuel in the future.

Parekh and Goswami (2012) utilized over the waste cooking oil

methyl ester as fuel and review results indicated that biodiesel derived from

used cooking oil is a cheap green liquid fuel available because of the primary

ingredient being a post-consumer waste product.

Patil (2012) detailed the production of fuel quality biodiesel from

low-cost high FFA waste cooking oil. A two-step transesterification process

was used to convert the high free fatty acid oil to its ester. Microwave-assisted

transesterification of waste cooking oil using heterogeneous and

homogeneous mixture was investigated for optimum reaction conditions.

Among the above method micro- wave-heating method is energy-efficient

and better than the conventional heating method

42

Many researchers have studied the performance and emission

characteristics of diesel engine using different grades of biodiesel at standard

parameters like compression ratios, injection timing and injection pressure

etc. But very little research has been done so for by varying the compression

ratios, injection timing and injection pressure.

2.4.1 Literature Summary for Edible, Non-edible and Cooking Oils

The summary of the literature review about biodiesel identification

and engine input and output parameters are as follows:

1. The vegetable and cooking oils are converted into biodiesel

and blend with diesel for higher percentages on a volume

basis in order to reduce viscosity and to avoid fuel filters

chocking and poor atomization.

2. From the observation of above literature review, higher

percentage of biodiesel blends with diesel is directly used in

the diesel engine for long term operation.

3. Another observation of the review is that the cost of the higher

percentage of edible, non-edible and cooking oil blends used

in a diesel engine is not much varied compared to diesel.

4. Also, the engine output parameters such as performance and

combustion results of vegetable and cooking oils are similar to

diesel, and the emission results are lower than diesel.

5. Method of transesterification is mostly used to convert

biodiesel from vegetable and cooking oils.

6. Biodiesels properties are measured as per ASTM D 6751

standards of vegetable and cooking oil methyl ester. Those

43

properties are well within the limits of ASTM & EN

standards.

Based on the literature summary the following objectives are

considered in the thesis;

The present work of methyl ester based fuels , corn oil methyl ester,

palm oil methyl ester, waste cooking cotton seed methyl ester and waste

cooking rice bran methyl ester are chosen as fuels for variable compression

ratio multi-fuel engine and the following proportions of blends are chosen –

B20, B40, B60, B80 and B100. The different blends of above chosen

biodiesel will be prepared and the following investigations will be carried out.

The combustion characteristics such as heat release rate,

ignition delay and combustion pressure will be discussed with

reference to the crank angle for various blends of different

compression ratios at full-load conditions and it will be

compared with the result of standard diesel fuel.

The performance characteristics such as brake thermal

efficiency, specific fuel consumption and exhaust gas

temperature of a variable compression ratio engine using

different blends at different compression ratios like 17:1, 18:1

and 19:1 for full-load are compared with the result of standard

diesel fuel.

The emission characteristics such as CO, CO2, HC, Nox and

smoke will be discussed with reference to the compression

ratio for various blends of different compression ratios at full-

load conditions and it will be compared with the result of

standard diesel fuel.

44

2.5 VARYING COMPRESSION RATIO

Bhatt et al. (2004) oriented the studies around the performance of

diesel engine being evaluated using different compression ratios of Mahua oil

as a fuel and it blends with diesel. The results showed that 20% and 40% of

Mahua oil used in diesel yielded the best performance at higher compression

ratios.

Yamin and Dado (2004) investigated the performance simulation of

a four-stroke engine with variable stroke-length and compression ratios. The

results concluded that the indicated power of the engine has increased up to

62% over that of the ordinary constant-stroke engine and lower engine speed

performance in terms of power developed and fuel consumption has

noticeably improved.

Raheman and Ghadge (2008) concluded that the performance of the

engine with higher compression ratios was improved, injection timing and

injection pressure with lower emissions, was still lower than the diesel fuel of

different loads and biodiesel.

The investigation of Rao et al. (2009) was carried out on a single

cylinder variable compression ratio CI engine using neat mahua oil as the

fuel. Performance and emission analysis were carried out to find the best

suited compression ratio. The results show that 15.7 is the best compression

ratio with mahua oil. BTE is very high at this compression ratio whereas fuel

consumption, smoke number and the exhaust gas temperatures are marginally

low at compression ratio 15.7.

45

Selvan et al. (2009) investigated the combustion characteristics of

diesohol using biodiesel as additive in a direct injection compression ignition

engine under various compression ratio. The result concluded that the

cylinder gas pressure, maximum rate of pressure rise and heat release rate

increase with higher ethanol concentrations due to longer ignition delay. Also,

it was found that the ignition delay decrease with the increase in compression

ratio and mean effective pressure.

Venkatraman and Devaradjane (2010) observed that the increase in

compression ratio, injection timing and injection pressure increase the

performance with lower emissions for pungam methyl ester as compared to

diesel. The optimum parameters were also evaluated.

Jindal et al. (2010) investigated the effect of compression ratio and

injection pressure in a diesel engine using jatropha methyl ester as fuel. From

this study it was observed that the best possible combination of the

compression ratio and injection pressure were determined and also improved

the performance of the engine with higher compression ratio and injection

pressure, marginal deteriorations of some emissions, which are still lower

than that with diesel fuel.

Muralidharan and Vasudevan (2011) studied the effect on

performance, emission and combustion characteristics of a multi-fuel variable

compression ratio engine fuelled with waste cooking oil biodiesel and diesel

blends at different compression ratio and the results are compared with that of

standard diesel. The results concluded that best combinations of performance,

emission and combustion parameters were found from suitable compression

ratio at partial load.

46

Anand et al. (2011) illustrated the performance and emissions of a

variable compression ratio diesel engine fuelled with biodiesel from

cottonseed oil. It was concluded that combustion characteristics came closer

to diesel and emissions were lower than for diesel. Also, the optimum

performance was obtained from different compression ratios.

Banapurmath et al. (2012) revealed the performance and emission

characteristics of honge oil as biodiesel used in compression ignition engine.

The results revealed that brake thermal efficiency increases with increase in

compression ratio and with further increase in compression ratio the

efficiency also increases with injection pressure. The optimum combinations

of emission parameter were also evaluated.

Mohanraj and Kumar (2012) ratified the operating characteristics of

a single cylinder four stroke variable compression ratio engine fueled with

esterified Tamanu oil. The performance characteristics and emission

characteristics of biodiesel were analyzed for Tamanu oil in the variable

compression ratio engine. The motivation behind this analysis was to fix the

effective compression ratio for biodiesel.

Amarnath and Prabhakaran (2012) envisaged the performance and

emissions of a variable compression ratio diesel engine fuelled with Karanja

biodiesel. Results showed that at a higher compression ratio, the engine gave

lesser emission and better performance. The genetic algorithm optimization

technique was used to optimize the parameters. With respect to maximum

efficiency and minimum emissions, the optimum values of load, compression

ratio, injection pressure, and blend were 6 kg, 18, 247 bar, and B95,

respectively.

47

Mathur et al. (2012) characterized the optimum compression ratio

for variable compression ratio diesel engine fuelled with diesel. The test

results revealed that compression ratio 17 exhibited better performance and

lower emissions and hence this was considered as an optimum compression

ratio.

Patel and Kirar (2012) conducted experiments on the performance

and emission analysis, and was found that when the compression ratio

increases brake thermal efficiency (BTE) increases and brake specific fuel

consumption (BSFC) decreases. The results of brake power remain unaffected

by changing compression ratios.

Duraisamy et al. (2012) illustrated the various performance and

emission parameters of diesel engine using methyl ester of thevetia peruviana

seed oil as biodiesel. It was found that the performance of the engine

increased appreciably with less BSFC by increasing the compression ratio for

biofuel blend. Also, it was observed that an increase in compression ratio

significantly reduced the CO, HC, NOx and smoke emissions.

2.5.1 Literature Summary for Varying Compression Ratio

1. The engine output parameters such as performance, emission

and combustion characteristics of different grade of vegetable

oils and waste cooking oils were investigated at standard

compression ratio. But very little work has focussed on pre-

heated palm oil, palm and corn oil methyl ester, waste cooking

cotton seed and rice brand methyl ester.

From the literature it can be inferred that:

48

1. Numerous works have been carried out on evaluating the

performance, emission and combustion characteristics of

different grades of pre-heated vegetable oil blends, vegetable

oil methyl esters and waste cooking oil methyl esters at

standard compression ratio, but very little work has been done

so far in evaluating the performance of pre-heated palm oil

blends with diesel, COME, POME, WCCSME and

WCRBME.

2. The effect of compression ratio has not been analyzed for the

above discussed oil blends with diesel. These oils have the

potential to become an alternate for conventional diesel oil.

Hence, the study on the characteristics of PHPO, COME,

POME, WCCSME and WCRBME on diesel engine for

variable compression ratio is very essential.

The present study has wide open pathways to investigate on

different compression ratios and combustion characteristics of above PHPO

and biodiesels for different blends by highlighting their effects on

performance and emission characteristics. This research provides complete

understanding and comprehensive analysis of the effect of compression ratio

on combustion, performance, and emission characteristics of PHPO, COME,

POME, WCSME and WCRBME, when it is compared with PBDF.

2.6 ARTIFICIAL NEURAL NETWORK

ANN is used for predicting the output parameters of the engine

with some input data available. It is a powerful modeling technique that

investigators have employed in many engineering research studies. Few

studies are concerned with the application of ANN and are reported for

49

predicting the performance and emission for CI engines. The brief review of

ANN is discussed below,

Parlak et al. (2006) studied the ability of an artificial neural

network model, using a back propagation learning algorithm, to predict

specific fuel consumption and exhaust temperature of a diesel engine for

various injection timings. The proposed new model was compared with

experimental results. The results were compared and it showed that the

consistence between experiment and the network results are achieved with a

mean absolute relative error less than 2%. It was concluded that a well-trained

neural network model provides fast and consistent results.

Najafi et al. (2007) reviewed the combustion analysis of a CI

engine performance using waste cooking biodiesel as fuel with ANN aid. The

results showed that the training algorithm of back propagation was sufficient

enough in predicting the engine torque, specific fuel consumption and exhaust

gas components for different engine speeds and different fuel blend ratio. It

was found that the R2 (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.

Sayin et al. (2007) explored the ANN modeling of a gasoline

engine to predict the brake specific fuel consumption, brake thermal

efficiency, exhaust gas temperature and exhaust emissions of the engine. The

performances of the ANN predictions were measured by comparing the

predictions with the experimental results which were not used in the training

process. It was observed that the ANN model can predict the engine

performance, exhaust emissions and exhaust gas temperature quite well with

correlation coefficients in the range of 0.983–0.996, mean relative errors in

the range of 1.41–6.66% and very low root mean square errors. The results

50

revealed that as an alternative to classical modeling techniques, the ANN

approach can be used to accurately predict the performance and emissions of

internal combustion engines.

Ganapathy (2009) created the artificial neural network model of

diesel engine fueled with jatropha oil to predict the unburned hydrocarbons,

smoke, and Nox emissions. The best linear fit of regression to the ANN

models of HC, smoke, and Nox emissions have yielded the correlation

coefficient values of 0.98, 0.995, and 0.997, respectively. The results may

easily be well thought-out to be within acceptable limits. Hence, these ANN

models may be considered for predicting the emissions in jatropha oil fueled

diesel engines.

Yusaf et al. (2010) exemplified the use of ANN modeling to predict

brake power, torque, BSFC and exhaust emissions of a diesel engine modified

to operate with a combination of both compressed natural gas (CNG) and

diesel fuels. A single-cylinder, four-stroke diesel engine was modified for the

work and was operated at different engine loads and speeds. For the ANN

modeling, the standard back-propagation algorithm was found to be the

optimum choice for training the model. A multi-layer perception network was

used for non-linear mapping between the input and output parameters. It was

found that the ANN model was able to predict the engine performance and

exhaust emissions with a correlation coefficient of 0.9884, 0.9838, 0.95707,

and 0.9934 for the engine torque, BSFC, NOx and exhaust temperature,

respectively.

Kiani et al. (2010) presented the ANN modeling of a spark ignition

engine to predict engine thermal balance. The performance of the ANN was

validated by comparing the prediction data set with the experimental results.

Results showed that the ANN provided the best accuracy in modeling the

thermal balance with a correlation coefficient equal to 0.997, 0.998, 0.996 and

51

0.992 for useful work, heat lost through exhaust, heat lost in the cooling water

and unaccounted losses, respectively.

Shivakumar et al. (2011) examined the performance and emission

characteristics of a variable compression ratio CI engine using WCO as a

biodiesel at different injection timings. The results revealed that ANN

modeling compete for predicting engine performance and emission

characteristics of developing individual models and also a combined model.

This reduces the experimental efforts and hence can serve as an effective tool

for predicting the performance of the engine and emission characteristics

under various operating conditions with different biodiesel blends.

2.6.1 Literature Summary of Artificial Neural Net Work

The summaries of literature review about the uses of ANN

modeling in engines are detailed below:

1. ANN technique was successfully employed to develop a

neural network model to predict engine performance

characteristics.

2. Application of fractional factorial with a number of

experimental runs was successfully employed to collect data

for developing the ANN model.

3. A correlation coefficient was obtained within the limits from

training, testing, and validation of all the data.

4. ANN techniques were used to find the relationship between

the experimental data and the developed model.

From the literature it can be inferred that:

52

1. The ANN model developed by most researchers are based on

load with performance of diesel engine but no ANN model

was available to predict the performance parameters based on

different compression ratios and full-load.

2. The accuracy of the ANN model is highly dependent on the

number of neurons in the hidden layer but no work has

focused on this aspect. Hence, it is absolutely essential to find

sufficient neurons in the hidden layer that can predict the

brake thermal efficiency and specific fuel consumption with

high accuracy.

Hence, in the present work, ANN model has to be developed to

predict the brake thermal efficiency and specific fuel consumption of different

compression ratios and full-load from different grade of biodiesels and PHPO.

Also, the best performance fuel has to be found through the ANN model and

then compared with experimental data.

53

2.7 BIODISEL RESEARCH – RECENT STUDIES

Hossain et al., (2013) investigated the performance, emission and

combustion characteristics of an indirect injection multi-cylinder CI engine

fuelled by blends of de-inking sludge pyrolysis oil with biodiesel. De-inking

sludge can be converted into useful forms of energy to provide economic and

environmental benefits. In this study, pyrolysis oil produced from de-inking

sludge through an intermediate pyrolysis technique was blended with

biodiesel derived from waste cooking oil, and tested in a multi-cylinder

indirect injection type CI engine. At full engine load, the brake specific fuel

consumption on a volume basis was around 6% higher for the blends when

compared to fossil diesel. The brake thermal efficiencies were about 3–6%

lower than biodiesel and were similar to fossil diesel. Exhaust gas emissions

of the blends contained 4% higher CO2 and 6–12% lower Nox, as compared to

fossil diesel. The study concludes that up to 20% blend of de-inking sludge

pyrolysis oil with biodiesel can be used in an indirect injection CI engine

without adding any ignition additives or surfactants.

An et al. (2013) conducted the experimental study of diesel engine

and to evaluate the performance, combustion and emission characteristics of

pure biodiesel and its blend fuels. For each tested fuel, the performance and

emissions were measured at four different engine speeds (800 RPM,

1200 RPM, 2400 RPM and 3600 RPM) under three different loads (25%,

50% and 100% load). The brake thermal efficiency of biodiesel was found to

be slightly higher compared to diesel at 50% and 100% load and the opposite

tread was observed at 25% load. But the opposite trend was seen at low

engine speed, revealing that the low engine speed had a significant effect on

the engine combustion and emission formation processes.

54

Kalam et al. (2011) studied the emission and performance

characteristics of an indirect ignition diesel engine fuelled with waste cooking

oil. This paper presents the experimental study carried out to evaluate

emission and performance characteristics of a multi-cylinder diesel engine

operating on waste cooking oil such as the 5 % palm oil with 95% ordinary

diesel fuel (P5) and 5% coconut oil with 95% ordinary diesel fuel (C5). B0

was used for comparison purposes. The results show that there are reductions

in brake power of 1.2% and 0.7% for P5 and C5 respectively compared with

B0. In addition, reduction of exhaust emissions such as unburned hydrocarbon

(HC), smoke, carbon mono-oxide (CO), and nitrogen oxides (Nox) is offered

by the blended fuels.

An et al. (2012) investigated the performance, combustion and

emission characteristics of diesel engine fueled by biodiesel at partial load

conditions. A largest increase of 28.1% in BSFC is found at 10% load.

Whereas for BTE, the results show that the use of biodiesel results in a

reduced thermal efficiency at lower engine loads and improved thermal

efficiency at higher engine loads.

Mekhilef et al. (2011) reviewed the technology aspect used in the

palm oil biodiesel production and characteristics of pure palm oil biodiesel to

meet the international market standard. The scope of this study covers the

worldwide biodiesel development in brief in continuation with the challenges

faced by Malaysia in becoming the top biodiesel exporter in the world with

the advantages and disadvantage of using palm oil as the feedstock.

55

Ong et al. (2011) reviewed the production, performance and

emission of palm oil, Jatropha curcas and Calophyllum inophyllum biodiesel.

Palm oil is one of the most efficient oil bearing crops in terms of oil yield,

land utilization, efficiency and productivity. However, competition between

edible oil sources as food with fuel makes edible oil not an ideal feedstock for

biodiesel production. Therefore, attention is shifted to non-edible oil like

Jatropha curcas and Calophyllum inophyllum. Calophyllum inophyllum oil

can be transesterified and being considered as a potential biodiesel fuel.

Ozener et al. (2012) studied the combustion, performance and

emission characteristics of conventional diesel fuel and biodiesel produced

from soybean oil and its blends (B10, B20, B50) were compared. Biodiesel

significantly reduced carbon monoxide (CO) (28–46%) and unburned total

hydrocarbons (THCs), while the nitric oxides (NOx) (6.95–17.62%) and

carbon dioxide (CO2) emissions increased slightly 1.46–5.03%. The

combustion analyses showed that the addition of biodiesel to conventional

diesel fuel decreased the ignition delay and reduced the premixed peak. These

results indicated that biodiesel could be used without any engine

modifications as an alternative and environmentally friendly fuel.

Yilmaz et al. (2014) studied the ethanol was mixed with

biodiesel–diesel blends and the effect of ethanol concentration of diesel

emissions was investigated. Both low and high concentrations of ethanol were

studied. Ethanol concentrations were varied at 3%, 5%, 15% and 25% in

biodiesel–diesel–ethanol (BDE), while biodiesel and diesel concentrations

were maintained equal (BDE3, BDE5, BDE15 and BDE25). Emission

characteristics for biodiesel–diesel–ethanol blends were compared to baseline

curves of diesel as a function of engine load.

56

Shehata, (2013) investigates the effects of biodiesel fuels on diesel

engine performance, Carbon monoxide (CO) and nitric oxide (NOX)

emissions, exhaust gas temperature (T Exhaust), oil temperature (T Oil), wall

temperature (TWall), and cylinder pressure with/without exhaust gas

recirculation (EGR). The present work contributes in using biodiesel fuels as

an alternative fuel for diesel engines without major change for engines parts.

For comparison between biodiesel and diesel fuels, the viscosity is not the

main parameter affecting on engine performance and emissions.

Jaichander and Annamalai, (2012) studied the improved thermal

efficiency, reduction in fuel consumption and pollutant emissions from

biodiesel fueled diesel engines are important issues in engine research. The

combined effects of varying, injection pressure and combustion chamber

geometries, on the combustion, performance and exhaust emissions, using a

blend of 20% POME (pongamia oil methyl ester) by volume in diesel were

evaluated. The test results showed that improvement in terms of brake thermal

efficiency and specific fuel consumption for TRCC (toroidal re-entrant

combustion chamber) operated at higher injection pressure.

Vallinayagam et al. (2014) conducted the experiment with a new

type of biofuel, pine oil, is introduced in this work for the purpose of fueling

diesel engine. The viscosity, boiling point and flash point of the reported oil is

lower, when compared to that of diesel. Also, the calorific value of pine oil

biofuel is comparable to diesel. As a result, it can be directly used in diesel

engines without trans-esterifying it. The results show that at full load

condition, 100% pine oil reduces CO (carbon monoxide), HC (hydrocarbon)

and smoke emissions by 65%, 30% and 70%, respectively. The brake thermal

efficiency and maximum heat release rate increase by 5% and 27%,

respectively. The experimental work reveals that 100% pine oil can be

57

directly used in diesel engine and potential benefits of pine oil biofuel have

been reaped.

Mohanraj and Kumar, (2012) investigate the operating

characteristics of a single-cylinder four-stroke variable compression ratio

engine fueled with esterified Tamanu oil were investigated. The suitability of

esterified Tamanu oil produced from pinnai oil by transesterification process

has been studied in variable compression ratio engine. The performance

characteristics like specific fuel consumption, brake power, mean effective

pressure, brake thermal efficiencies, and exhaust gas temperature are analyzed

for Tamanu oil in the variable compression ratio engine. The motivation

behind this analysis was to fix the effective compression ratio for biodiesel.

2.7.1 Literature Summary of recent studies on biodiesel research

1. The recent studies of the above literature of different type of

biodiesel are related to in this research are studied and presented in elaborate

survey.

2. Also, studied the different type of input and output parameters

used in CI engines for different type of biodiesel