Renewable Fuels for Transportation-Amba Prasad

8/7/2019 Renewable Fuels for Transportation-Amba Prasad

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Renewable Fuels forTransportation

Dr. G. Amba Prasad RaoDepartment of Mechanical Engineering

National Institute of Technology

Warangal- 506 004. (A.P.)


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Preamble

Thanks to the inventors of Internal Combustion engine, especially CI engine, that has

changed the life style of human beings. Ever since the invention of IC Engine, inparticular CI engine, multitude of improvements has taken place with regards to the

engine design technology. Two centuries of unprecedented industrialization driven

mainly by the fossil fuels have changed the face of this planet. Serious smog problem

of early 1960s in Los angles has diverted the minds of technologists to reduce

pollutants responsible for smog episode. Added to this, early 1970s had witnessed the

oil embargo and since then the researchers started working seriously on search for

substitute fuels to replace petroleum derived fuels to keep the automotive industry

alive. Pollution and accelerating energy consumption have already affected equlibria

of earths landmasses, oceans and atmosphere, particularly important is the loss of

biodiversity.

Countries like ours and in general countries that have less reserves of petroleum crude

are losing their hard earned revenue in importing petro- products to sustain their

vehicle population.

To keep the vehicles moving, adapting to the latest engine technology and to curb

vehicular pollution problems, the petroleum fuels are undergoing extensive refining

process to improve ignition quality and make sulfur free petroleum fuels.

Researchers have established the feasibility of using a variety of alternative fuels such

as alcohol fuels, natural gas, hydrogen, and a host of vegetable oils.

In the present workshop, an overview of renewable fuels that can be substituted for

petro-derived fuels has been presented.


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Introduction:

Fuels are those substances which, when heated, undergo chemical reaction with an

oxidizer (typically oxygen in air) to liberate heat. Commercially important fuelscontain carbon, hydrogen, and their compounds, which provide the heating value.

Fuels may be classified as liquid, gaseous or solid.

Liquid fuels haven meeting the demands in transportation and heavy-duty, power

sectors and are primarily derived from crude oil. Thus they are predominantly

petroleum derived fuels (fossil) .To be practical sources of energy; fuels should be

abundant and relatively inexpensive. The extent of global fossil fuel reserves is

subject to debate. The fuels most commonly used in internal combustion engines-IC

Engines(gasoline or petrol, and diesel fuels) are blends of many different hydrocarbon

compounds obtained by refining petroleum or crude oil; typically about 86 percent

carbon and 14 percent hydrogen by weight, though diesel fuels contain up to about 1

percent sulfur.

Combustion is such a commonly observed phenomenon that it hardly seems

necessary to define the term. From a scientific view point, combustion stems from

chemical reaction kinetics. Reactions which take place very rapidly with large

conversion of chemical energy to sensible energy (thermal energy). Typical

combustion products of hydrocarbon fuels are carbon dioxide, water vapor and traces

of carbon monoxide and oxides of nitrogen. Large-scale exploitation of petroleum

derived fuels by energy hungry nations for meeting the requirements for various

reasons have exponentially increased the obnoxious emissions (Combustion

generated pollution). Combustion emissions must satisfy governmentally imposed

emission standards (Euro norms, EPA norms and Bharat Stage norms etc.) for

selected compounds in the products, such as carbon monoxide, hydrocarbons,

nitrogen oxides, and particulate emissions. Emissions standards are set at levels to try

to keep the ambient air clean enough to protect human health and the natural

environment. Low emissions can be achieved by a combination of fuel selection and

preparation, combustion system design, and treatment of the products of combustion.


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There are challenging engineering trade-offs between low emissions, high efficiency,

and low cost.

Recently, global warming has become a widespread concern. Inter governmental

Panel for Climate Change (IPCC) recommendations have also strongly established

that human activities are responsible for alarming levels in greenhouse gases in the

atmosphere. The described that carbon dioxide levels, in the global atmosphere are

increasing, and carbon dioxide emissions from combustion are a major contributor to

the greenhouse effect, whereby long-wave radiation from the surface of the earth is

trapped by the atmosphere. The relationship between CO2 emissions and average

global temperature rise is not clear at this time. However, it is well established that

the CO2 concentration in the atmosphere is increasing at an accelerating rate. Prior to

the industrial revolution the CO2 content of the atmosphere was fairly stable at 280

parts per million (ppm), based o measurements of air bubbles trapped in glacial ice

corings. By 1900 the CO2 level had reached 300ppm. Accurate, direct measurements

of atmospheric carbon dioxide concentrations were begun by Charles Keeling at the

Mauna Loa Observatory in 1958 the CO2 concentration was 315ppm; by 1980,

337ppm; and by 1996, 362 ppm. Because the world population is expected to nearly

double to around 10 billion people during the next several decades, the potential for

future growth in CO2

emissions cannot be ignored. The worldwide pressure for

growth in fuel consumption and CO2 emissions is tremendous, as evidenced, for

example, by the fact that one-third of the people in the world still do not have any

electricity.

A reduction in CO2 emissions can be achieved by improvement in the overall

efficiency of combustion systems, by using renewable fuels, and by replacing fossil

fuels with other sources of energy such as solar photovoltaic, wind, geothermal,

hydro, or nuclear power.

Researchers have established the use of both liquid and gaseous alternative fuels for

use in CI and CI engines viz; Alcohols (Methanol and Ethanol), Natural gas,

Hydrogen, Biofuels (especially biodiesel).

Alternative Fuels-An overview:


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alternative fuels are less reactive. This results in reduced amounts ozone being

produced with the benefit of improved air quality. In the starting there was less

concern about energy security but later on developed countries felt it necessary and

swung back to the energy security value of alternative fuels. As emission control

technology combined with cleaner petroleum fuels such as reformulated gasoline and

clean diesel has resulted in emission levels low enough to significantly depreciate

the emission benefits of alternative fuels.

The initial work on alternative fuels focused on which one was best from the view

point of technical feasibility production capability and cost.Technical feasibility is no

longer questioned, and the focus now has shifted more toward which alternative fuels

can be produced at competitive cost. New issues such as public awareness and

training of vehicle maintenance personnel have arisen as the use of alternative fuel

vehicles spreads.

The alternative fuels suggested are those which are considered the most likely

candidates for use in IC Engine and future energy conversion devices such as fuel

cells. The alcohols (methanol and ethanol) natural gas (compressed and liquefied) LP

Gas and vegetable oils and hydrogen are all covered in their entirety.

The Alcohol Fuels

Methanol and ethanol are the alcohols considered to be potential transportation

alternative fuels. None of the alcohols higher than methanol and ethanol have been

seriously considered as alternative fuels for use unmixed with other fuels in engines.

Tertiary butyl alcohol (TBA) has been used as a gasoline and co-solvent when mixing

methanol with gasoline, but not as a duel by itself. Recently, dimethyl ether (DME,

made using methanol) has been proposed for use as a diesel engine alternative fuel

because of its favorable emissions characteristics relative using diesel fuel.

Methanol and ethanol make good candidates for alternative fuels in that they are

liquids and have several physical and combustion properties similar to gasoline and


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diesel fuel. These properties are similar so that the same basic engine and fuel system

technologies can be used for methanol and ethanol as for gasoline and diesel fuel.

Both methanol and ethanol have much higher octane ratings than typical gasoline-

which allows alcohol engines to have much higher compression ratios, increasing

thermal efficiency. However, a significant drawback to methanol and ethanol relative

to gasoline is that they lower energy density, i.e., fewer Btus per gallon. It takes

nearly two gallons of methanol and one-half gallons of ethanol to equal one gallon of

gasoline.

Methanol and ethanol have inherent advantages relative to conventional gasoline and

diesel fuel in that their emissions are less reactive in the atmosphere, producing

smaller amounts of ozone, the harmful component of smog. The mass of emissions

using methanol and ethanol is not significantly different than from petroleum fuels.

Methanol and ethanol have the disadvantage in that they produce formaldehyde and

acetaldehyde as combustion by products in large quantity than the toxic compounds

from the petroleum fuels that they replace.

Methanol and ethanol were long considered good SI engine alternative fuels. Clever

implementation of ignition aids and use of fuel additives in the 1970s and 1980s

proved that it was possible use methanol and ethanol as diesel engine alternative

fuels. A significant advantage of alcohol fuels is that when are combusted in diesel

engines, they do not produce any soot or particulates and they can be tuned to also

produce very low levels of oxides of nitrogen.

Table-1 lists the properties of pure methanol, pure ethanol compared to gasoline and

No.2 diesel fuel.

Methanol

Consideration of methanol as motor fuel did not emerge until it became a common

industrial chemical. It was used as an automotive fuel during the 1930s to replace or

supplement gasoline supplies, in high performance engines in grand prix racing


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vehicles in the 1930s. For general use, serious research attention started in the late

1960s based on emissions advantages and was greatly expanded when energy security

problems developed in the 1970s(Oil embargo).Air quality has become the near-term

catalyst for alternative fuel vehicle expansion, but in the long-term the countries will

have to rely on alternative sources of energy as petroleum reserves diminish. With the

US government-mandated phase out of lead as a gasoline octane additive, low

concentrations of methanol were found to be a good nonmetallic substitute. MTBE is

made by reacting methanol with iso-butylene, is an octane blending agent with more

favorable characteristics than methanol to produce blends with gasoline for use in

existing gasoline vehicle models.

Methanols major advantages in vehicular use are that it is a convenient, familiar

liquid fuel that can readily be produced using well-proven technology.

Major disadvantages of methanol are: initial higher cost than that of gasoline; impact

of reduce energy density on driving range or larger fuel tank; it burns with a flame

that is not visible in direct sunlight; and need for education of users and handlers on

toxicity safety.

Production:

Methanol is a colorless liquid that is common chemical used in industry as solvent

and directly in manufacturing processes. Methanol was once referred to as wood

alcohol because it originally was made from the destructive distillation of wood. The

technology for large-scale production of methanol was developed by Badische Anilin

und Fabrik(BASF) in Germany in 1924.

The currently preferred process for producing methanol is steam reformation of

natural gas. In this process, any sulfur present in natural gas is first removed. Next,

the natural gas is reacted with steam in the presence of a catalyst under high heat and

pressure to form carbon monoxide and hydrogen. These elements are then put

through the methanol production catalyst to make methanol. There are many

variations of the basic steam reforming process, all aimed at increasing the overall

thermal efficiency. Steam reformation of natural gas has a thermal efficiency of about

56-62%, while advanced processes can have as high as 68%.Larger methanol


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production plants are more efficient than smaller ones. The size of a large (world-

scale) methanol plant is in the range of 2000-2500 metric tons per day.

Other methods:

(i) Methanol from lignite or coal: Pulverized lignite or coal is fed to

steam/oxygen-blown gasifiers (partial combustion) to produce

synthesis gas consisting of CO and H2

H2O + C CO + H2

CO +H2 CH3OH

(ii) Methanol from Municipal Solid waste: The wastes are first shredded

and then passed under a magnet to remove ferrous materials. The iron

free wastes are then gasified with oxygen. The product synthesis gas is

cleaned by water scrubbing and other means to remove any

particulates, entrained oils, H2S and CO2.CO-shift conversion for H2 ,

CO and CO2 ratio adjustment, methanol synthesis, and methanol

purification are accomplished in a manner similar to that of lignite

feed.

Methanol burns without a visible flame, which is a safety concern, but which also

demonstrates that methanol does not produce soot or smoke when combusted. This

fact makes methanol a very attractive diesel engine fuel because, unlike diesel fuel,

no particulates are formed.

Methanol exposure studies have shown that methanol does not cause harm in the

quantities that would accumulate in the body from exposure fro refueling vapors or

from unburned methanol in vehicle exhaust. In addition, because of methanols high

latent heat of vaporization, peak combustion temperatures can be reduced with

correspondingly low emissions of oxides nitrogen (NOX).

The physical and chemical properties of methanol can be used advantageously in

engines to produce low emissions. Because it is less photochemically reactive than

gasoline, its evaporative emissions contribute less to smog formation; and because it

contains oxygen, it facilitates leaner combustion resulting in lower CO emission.

Evaporative emissions of methanol during transport, storage, dispensing, and use fall


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about mid way between gasoline and diesel fuel, but increase with the use of

gasoline/methanol blends.

Ethanol

Ethanol has long been considered a good spark-ignition engine fuel, and engines were

run on ethanol very early in engine development. Henry Ford was an early proponent

of using ethanol as a fuel because of its good combustion properties and because of

its potential self-sufficiency, i.e., it can be produced by the agriculture sector

which would satisfy their needs and sell the excess to others. Brazil, in fact, has

implemented this idea and is the only country around the world to have done so to

date.

Ethanol for use as a fuel is produced in almost all countries exclusively using

fermentation technology. In U.S. the preferred feed-stock is corn, though other grains

and crops such as potatoes and sugar-beets can be used. Agriculture wastes such as

cheese whey are also considered good feed stocks for ethanol production (Starches

are saccharified to sugars, which are then fermented. In Brazil, sugar cane is the

preferred feedstock for ethanol production because of favorable growing climate. In

France, ethanol is produced from grapes that are of insufficient quality for wine

production.

Ethanol is produced by fermentation of carbohydrates by the Gay Lussac relation

C6 H12O6 2 C2H5OH + 2CO2

What govern the choice of feedstock are cost and the capability for large-scale

production. Included in the cost is the amount of petroleum used to produce the crop

and then prepare it for fermentation. The petroleum used to produce ethanol reducesthe petroleum displacement value of ethanol as an alternative fuel.

About 1.5kg of sugar yields a liter of ethanol. Molasses contain a large percentage of

sugar, 30% or higher. The normal yield of ethanol is about 8.5liters of alcohol per

tons of cane processed in a sugar factory.

There are three primary ways that ethanol can be used as a transportation fuel:


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i) as a blend with gasoline, typically 10% and commonly known as

gasohol

ii) as a component of reformulated gasoline both directly and / or

transformed into a compound such as ethyl tertiary butyl ether(ETBE)

iii) used directly as a fuel, with 15% or more of gasoline known as E85.

Ethanol can also be used directly in diesel engines specially configured for alcohol

fuels.

Vehicle Emission Characteristics:

Ethanol by itself has a very low vapor pressure, but when blended in small amounts

with gasoline, it causes the resulting blend to have a disproportionate increase in

vapor pressure. For this reason, there is interest in using fuels such as ETBE as

reformulated gasoline components because ETBE has a small blending vapor

pressure (28kPa) which will reduce the vapor pressure of the resulting blend when

added to gasoline. The primary emission advantage of using ethanol blends is that CO

emissions are reduced through the blend leaning effect that is caused by the

oxygen content of the ethanol. The oxygen in the fuel contributes to combustion

much the same as adding additional air. Because this additional oxygen is being

added through the fuel, the engine fuel and emission systems are fooled into

operating leaner than designed, with the result being lower CO emissions and

typically slightly higher NOX emissions.

The emission characteristics of E85 vehicles are not as well documented as for M85

vehicles; however, Ford tested E85 in their 1996 model Taurus flexible fuel vehicle

and found essentially no difference in tailpipe emissions compared to using the

standard emissions testing gasoline (Indolene). In this test, the engine-out emissions

of HC and NOX were lower than for gasoline, but ethanols lower exhaust gas

temperatures were believed to decrease catalyst efficiency slightly so that the tailpipe

emissions were the same.E85 produces acetaldehyde instead of formaldehyde when

methanol or M85 is combusted. An advantage of acetaldehyde over formaldehyde is

that it is less reactive in the atmosphere which contributes less to ground-level ozone

formation.


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When ethanol is used as a blending component in gasoline there are typically few

discernable differences in vehicle driveability or performance to the driver of current

technology vehicles. Some older vehicles have experienced hot-start problems

because of increased volatility, and vehicles using ethanol blends after many years of

gasoline use may experience fuel filter plugging because the ethanol acts as a solvent

for gasoline deposits. There is no reason to believe that E85 vehicles should not last

as long as gasoline vehicles Long-term tests of M85 vehicles have been very

successful and have shown a similar engine wear to the same engines using gasoline.

This should hold true for E85 vehicles as well.

Fuel specifications represent an attempt to mold and limit fuel properties to facilitate

use in vehicles and limit the hazards presented in storing and handling fuels.

Petroleum fuels have an advantage here in that producers have some latitude to vary

the properties of the final product. There is no such option for some fuels such as

natural gas which predominantly methane, and ideally would be 100% methane.

Methanol and ethanol are also single-constituent fuels, but it is possible to vary their

properties advantageously through the addition of gasoline or other additives.

The effects of different ethanol-diesel blended fuels on the performance and

emissions of diesel engine have been investigated experimentally by De-gang Li etal., (2005) to find an optimum blend for the chosen engine and conditions. They

observed that brake specific fuel consumption and brake thermal efficiency have

increased with the increase in ethanol content in the blends. They concluded that for

E10-D and E15-D blends, CO, NOX emissions have decreased where as total

hydrocarbon emissions have increased. The characteristics are illustrated in the

following figures


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Natural Gas

Natural gas is a naturally occurring fuel found in oil fields (one of the worlds most

abundant fossil fuel).It is primarily composed of about 90 to 95% methane (CH4),with small traces of additional compounds such as 0-4% nitrogen, 4% ethane, and 1-

2% propane. Methane is a greenhouse gas, with global warming potential

approximately 10 times that of CO2. Methane has a lower carbon to hydrogen ratio

relative to gasoline, so its CO2 emissions are about 22-25% lower than gasoline.

Natural gas fuelled vehicles (NGV) have been in use since the 1950s, and conversion

kits are available for both spark and compression ignition engines. Recent research

and development work has included development of bifuel vehicles that can operate

either with natural gas and gasoline or diesel fuel. One advantage of a bifuel

operation is that the operation range of a vehicle is extended in comparison with a

dedicated natural gas vehicle.

Natural gas is stored in a compressed(CNG) state at room temperatures and also in a

liquid (LNG) form at -160OC. Natural gas has an octane number (RON) of about 127,

so that Natural gas engines cam operate at a compression ratio of 11:1, greater than

gasoline fueled engines. Natural gas is pressurized to 22MPa in vehicular storage

tanks, so that it has about 1/3 of the volumetric energy density of gasoline. The

storage pressure is about 20 times that of propane. Like propane, natural gas is

delivered to the engine through pressure regulator, either through a mixing valve

located in the intake manifold, port fuel injection at about 750kPa, or direct injection

into the cylinder. With intake manifold mixing or port fuel injection, the engines

volumetric efficiency and power is reduced due to the displacement of about 10% of

the intake air by the natural gas, and the loss of evaporative charge cooling. Natural

gas does not require mixture enrichment for cold starting, reducing the cold start HC

and CO emissions.

The combustion of methane is different from that of liquid hydrocarbon combustion

since only carbon hydrogen bonds are involved, and no carbon-carbon bonds, so the

combustion process is more likely to be more complete, producing less non-methane


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hydrocarbons. Optimal thermal efficiency occurs at lean conditions at equivalence

ratios of 1.3 to 1.5.the total HC emission levels can be higher than gasoline engines

due to unburned methane. The combustion process of methane can produce more

complex molecules, such as formaldehyde, a pollutant. The particulate emissions of

natural gas are very low relative to diesel fuel. Natural gas has a lower adiabatic

flame temperature (~2240K) than gasoline (~2310K), due to its higher product water

content. Operation under lean conditions will also lower the peak combustion

temperatures. The lower combustion temperatures lower the NO formation rate, and

produce less engine-out NOX.

Natural gas can replace diesel fuel in heavy duty engines with the addition of a spark

ignition system. A number of heavy duty diesel engine manufacturers are also

producing a dedicated natural gas heavy duty engines. The natural gas fueled engines

are operated lean with an equivalence ratio as low as 0.7. The resulting lower in-

cylinder temperatures reduce the NOX levels. Heavy duty natural gas engines are

designed to meet LEV emission standards without the use of an exhaust catalyst, and

will meet ULEV emission standards with the addition of a catalyst.

Experimental Investigations:

Natural gas can also be used in compression ignition engines if diesel fuel is used as a

pilot fuel, since the autoignition temperature of methane is 540OC, compared to

260OC for diesel fuel. This fueling strategy is attractive for heavy duty diesel

applications, such as trucks, buses, locomotives, and ships, compressors and

generators. These engines are also operated with a lean combustion mixture, so that

the NOX emissions are decreased. However, since diesel engines are unthrottled, at

low loads, the lean combustion conditions degrade the combustion process, increasing

the HC and CO emissions.

Carlucci et al.,(2007carried out experimental investigation and combustion analysis

of a direct injection dual-fuel dieselnatural gas engine. A single-cylinder diesel

engine has been converted into a dual-fuel engine to operate with natural gas together

with a pilot injection of diesel fuel used to ignite the CNGair charge. The CNG was

injected into the intake manifold via a gas injector on purpose designed for this

application. The main performance of the gas injector, such as flow coefficient,


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instantaneous mass flow rate, delay time between electrical signal and opening of the

injector, have been characterized by testing the injector in a constant-volume optical

vessel. The CNG jet structure has also been characterized by means of shadowgraphy

technique. The engine, operating in dual-fuel mode, has been tested on a wide range

of operating conditions spanning different values of engine load and speed. For all the

tested operating conditions, the effect of CNG and diesel fuel injection pressure,

together with the amount of fuel injected during the pilot injection, were analyzed on

the combustion development and, as a consequence, on the engine performance, in

terms of specific emission levels and fuel consumption.

Nwafor, 2007 experimentally investigated the effect of advanced injection timing on

emission characteristics of diesel engine running on natural gas . The test results

showed that alternative fuels exhibit longer ignition delay, with slow burning rates.

Longer delays will lead to unacceptable rates of pressure rise with the result of diesel

knock. This work examines the effect of advanced injection timing on the emission

characteristics of dual-fuel engine. The engine has standard injection timing of 301

BTDC. The injection was first advanced by 5.51 and given injection timing of 35.51

BTDC. The engine performance was erratic on this timing. The injection was then

advanced by 3.51. The engine performance was smooth on this timing especially at

low loading conditions. The ignition delay was reduced through advanced injection

timing but tended to incur a slight increase in fuel consumption. The CO and CO2

emissions were reduced through advanced injection timing.

Hydrogen

Hydrogen is the only alternative fuel that does not contain any carbon or oxygen. It is

the lightest fuel possible, with a molecular weight of only 2.02. Even as liquid,

hydrogen is only about one-tenth the weight per liter of gasoline (but has about one-

quarter the energy). Hydrogen has many characteristics that make it the ultimate

alternative fuel to fossil fuels. Hydrogen can be combusted directly in IC Engines or


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it can be used in fuel cells to produce electricity with high efficiency (30-50% over

the typical load range). When hydrogen is oxidized in fuel cells, the only emission is

water vapor. When hydrogen is combusted in IC Engines, water vapor is again the

major emission, though some oxides of nitrogen may be formed if combustion

temperatures are high enough depending on the calibration of the fuel system and

configuration of the engine. Therefore, the use of hydrogen as a transportation vehicle

fuel would result in few or no emissions that would contribute to ozone formation.

Hydrogen (H2) can be produced from many different feed-stocks including natural

gas, coal, biomass and water. The production processes include steam reforming of

natural gas, presently the most economical method, electrolysis of water, and

gasification of coal which also produces CO2.

Electrolysis route is desirable from air quality standpoint only if the electricity is

made from sources that do not use fossil fuels such as hydropower or nuclear energy.

Hydrogen is colorless, odorless, and nontoxic, and hydrogen flames are invisible and

smokeless. The global warming potential of hydrogen is insignificant in comparison

to hydrocarbon based fuels since combustion of hydrogen produces no carbon-based

compounds such as HC, CO, and CO2.. Research is underway to develop novel, non-

polluting means of hydrogen production such as from algae that makes use of

sunlight or other biological methods. At present the largest user of hydrogen fuel is

the aerospace community for rocket fuel. Even if hydrogen is released (e.g., fuel

spills or vehicle maintenance) it rises quickly (being lighter than air) and does not

cause any reactions in the atmosphere.

The major drawback to using hydrogen as a fuel is the storage medium. Compared to

all other fuels, hydrogen has lowest energy storage density. Hydrogen can be stored

as compressed gas at pressures similar to CNG, liquefied, or stored in metal hydrides

(which absorb hydrogen when cool and release it when heated) or carbon absorbents.

A major concern about hydrogen vehicles will be operating range.

Liquefied hydrogen (LH2) is a cryogenic liquid- its boiling point is -253OC. Thus, the

storage containers for LH2 must have the best insulation available. The cold

temperatures of LH2 require storage tanks made from stainless steel. Storage


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containers for LH2 are even more expensive than for LNG because the insulation

requirements are more severe.

Hydrogen has the widest flammability range of all fuels-from 4 to 75 volume percent

in air. This wide flammability range has significant implications for hydrogen safety.

Hydrogen also tends to diffuse more readily than natural gas, so leaks of hydrogen

will tend to diffuse rapidly within a space and will be in the flammability range for a

long time in comparison to other fuels. Hydrogen also burns without a visible flame

in direct sunlight, which is an additional safety concern.

It has been discovered that spark-ignition IC Engines using hydrogen are prone to a

phenomenon called flash back, where backfires through the intake system occur

randomly with great force due to hydrogens fast flame speed( ~ 3m/s, about 10 times

that of methane and gasoline, and adiabatic flame temperature is about 100OC higher

than gasoline and methane. Flash back is believed to be caused by pre-ignition, and

the only sure solution known at present is to use direct cylinder injection of hydrogen.

For these reasons, octane rating of hydrogen is not as important as designing an

engine that will avoid flashback. The engine tests performed to date have used

compression ratios typical of those used for gasoline engines, so hydrogen engines

should not have a disadvantage in terms of basic engine thermal efficiency. Hydrogen

can also be combusted very lean, which gives it an efficiency advantage over gasoline

engines that must rely on stoichiometric mixtures and catalytic control of the exhaust

gases for emissions control.

Experimental Investigations:

Recently, Masood et al., 2007, experimentally investigated on a Hydrogen-Diesel

Dual Fuel Engine at Different Compression Ratios. The investigation was carried out

on a computer interfaced single cylinder variable compression ratio, compression

ignition engine to optimize the performance characteristics and to find the useful

higher compression ratio (UHCR) with hydrogen-diesel dual fuel mode.

Experimentations were conducted on five different compression ratios and the

performance characteristics were calculated. The effect of blending on NOx, HC, CO,

and particulate matter were measured and reported. The rate of heat release and speed


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of combustion with increase in compression ratio with simultaneous increase in

hydrogen substitution were measured. Intake temperature of air was increased and for

three different temperatures, the effect of increase in temperature of air-hydrogen

mixture on NOx were studied and found that there was a sharp increase in the NOx

value as the inlet temperature was increased from 65 to 85C.

The experiments were conducted on a hydrogen-diesel dual fuel engine under

constant speed, variable compression ratios, and variable load conditions. The amount

of primary fuel, i.e., diesel admitted was varied and hydrogen was substituted at each

load. The objective was to determine in detail the performance, emissions, and

combustion characteristics of the engine.


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Biofuels-Jatropha: the new crude oil?

In recent times, the share of fuels of bio-origin, such as alcohol, vegetable oils,

biomass, biogas, synthetic fuels, etc. is growing. Of the alternative fuels, biodiesel

obtained from vegetable oils holds good promises as an eco-friendly alternative to

diesel fuel. Biomass is a renewable energy source with very specific properties.

Compared to other renewable technologies such as solar thermal, photovoltaic (PV)

or wind, biomass has few problems with energy storage; in a sense, biomass is stored

solar energy, and is CO2 neutral when it burns. Another property of biomass is its

versatility. Biomass can produce biogas, liquid fuels, electricity or heat, but recent

public interest in bioenergy has been directed more towards liquid fuels and

electricity rather than heat. Biofuels offer multitude of benefits to the world:


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Sustainability

Reduction of green house gas emissions

Regional development

Rural employment

Social structure and agriculture

Security of supply

As far as significant feature of biofuel chemistry is concerned, it contains oxygen

molecule in its structure and thus require lesser external oxygen for their complete

combustion and also the biofuels are almost sulfur free fuels.

Biofuels have started becoming important part of transportation fuels in many

countries. Ethanol is the most widely used biofuel at present and Brazil is the

forerunner in its use. Biofuels are good option for agricultural dominated economic

countries.

Triglycerides as diesel fuels:

Vegetable oils are produced from plant seeds, also called seed oils or energy plant

oils. It is not now new to use vegetable oils in engines, the use dates back to 1917

when the great inventor of Diesel engine Sir Rudolph Diesel demonstrated his engine

with peanut oil at the French exposition.

The use of vegetable oils, such as palm, soya bean, sunflower, peanut, and olive oil,

as alternative fuels for diesel engines dates back almost nine decades, but due to the

rapid decline in crude oil reserves, it is again being promoted in many countries.

Depending upon the climate and soil conditions, different countries are looking for

different types of vegetable oils as substitutes for diesel fuels. For example, soya bean

oil in the US, rapeseed and sunflower oils in Europe, palm oil in South-east Asia

(mainly Malaysia and Indonesia) and coconut oil in the Philippines are being

considered. Besides, some species of plants yielding non-edible oils, e.g. jatropha,

karanji and pongamia may play a significant role in providing resources. Both these

plants may be grown on a massive scale on agricultural/degraded/waste lands, so that

the chief resource may be available to produce biodiesel on farm scale.


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Chemical composition:

Vegetable oils, also known as triglycerides comprise of 98% triglycerides and small

amounts of mono- and di-glycerides. Triglycerides are esters of three molecules of

fatty acids and one of glycerol and contain substantial amounts of oxygen in their

structure. The fatty acids vary in their carbon chain length and in the number of

double bonds.

Properties of vegetable oils as fuel:

The fuel properties of vegetable oils as listed in Table 3 [2,3] indicate that the

kinematics viscosity of vegetable oils varies in the range of 3040 cSt at 38OC. The

high viscosity of these oils is due to their large molecular mass in the range of 600

900, which is about 20 times more higher than that of diesel fuel. The flash point of

vegetable oils is very high (above 200OC). The volumetric heating values are in the

range of 3940 MJ/kg, as compared to diesel fuels (about 45 MJ/kg). The presence of

chemically bound oxygen in vegetable oils lowers their heating values by about 10%.

The cetane numbers are in the range of 3240.

Chemical structure of common fatty acids-Vegetable oils:

Host of vegetable oils can be grouped into two categories as edible type and non-

edible type. Sunflower, peanut, ground nut, rapeseed (canola), soybean palm oil are

few among the edible type while linseed oil, cottonseed, karanji, neem oil, honge oil

and Jatropha Curcas oil are examples for the non-edible type. As there is already a

great demand for edible type, research should be focused on the development and

commercialization of vegetable oil as a fuel from non-edible category.

Non-edible Jatropha Curcas oil is being chosen by the countries as a fuel for

investigation. It is popularly known as physic nut in some parts of the world. It is a

plant of Latin American origin which is now widespread throughout arid and semi-

arid tropical regions of the world. It is a drought-resistant perennial plant living up to

50 years and growing in all soils except vertisols, though light sandy soils are

preferred. Jatropha Curcas seeds contain about 32 to 35% non-edible oil. The

production of seeds is about 0.8kg per meter hedge per year. The plants can also

sustain without water for some days.


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26

By analyzing the Jatropha oil using Gas-Liquid chromatography it is found that the

saturated and unsaturated fatty acids contribute 20.1% and 79.9% of the oil

respectively.

Fatty acid Composition

Palmitic acid 12.8

Stearic acid 7.3

Oleic acid 44.8

Linoleic acid 34.0

Other acids 1.1

Utilization of vegetable oils as fuels:

Use of vegetable oils as diesel fuel

It has been found that these neat vegetable oils can be used as diesel fuels in

conventional diesel engines, but this leads to a number of problems related to the type

and grade of oil and local climatic conditions. The injection, atomization and

combustion characteristics of vegetable oils in diesel engines are significantly

different from those of diesel. The high viscosity of vegetable oils interferes with the

injection process and leads to poor fuel atomization. The inefficient mixing of oil

with air contributes to incomplete combustion, leading to heavy smoke emission, and

the high flash point attributes to lower volatility characteristics. These disadvantages,

coupled with the reactivity of unsaturated vegetable oils, do not allow the engine to

operate trouble free for longer period of time. These problems can be solved, if the

vegetable oils are chemically modified to biodiesel, which is similar in characteristics

to diesel.


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27

Researchers have handled the associated problems either suiting the engine to fuel or

processing the fuel to suit an engine.

The engine modifications included:

Dual-fuel mode operation

Employing high fuel injection pressures

Heated fuel lines

Supercharging

IDI engine concept

Hot combustion chamber concept LHR engine; where as the fuel

modifications covered

Blending with low viscous fuels

Pyrolysis/cracking

Micro-emulsification

Transesterification

Use of methyl or ethyl esters of vegetable oils-Biodiesel

Biodiesel is defined as the monoalkyl esters of long-chain fatty acids derived from

renewable feedstock, such as vegetable oil or animal fats, for use in compression

ignition engines. Biodiesel has been reported as a possible substitute or extender for

conventional diesel and is comprised of fatty acid methyl/ethyl esters, obtained from

triglycerides by transesterification with methanol/ethanol, respectively. Biodiesel is

compatible with conventional diesel and both can be blended in any proportion.

Preparation of biodiesel from sunflower oil, used frying oil, jatropha oil, karanji

(pongamia) oil, etc. as a source of triglycerides has been reported.

Fuel properties of biodieselThe properties of biodiesel (Methyl esters of any vegetable oil)and diesel fuels, as

given in Table- 1 show many similarities, and therefore, biodiesel is rated as a strong

candidate as an alternative to diesel. This is due to the fact that the conversion of

triglycerides into methyl or ethyl esters through the transesterification process reduces

the molecular weight to one-third, reduces the viscosity by about one-eighth, and


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28

increases the volatility marginally. Biodiesel contains 1011% oxygen (w/w), thereby

enhancing the combustion process in an engine. It has also been reported that the use

of tertiary fatty amines and amides can be effective in enhancing the ignition quality

of the biodiesel without having any negative effect on its cold flow properties.

However, starting problems persist in cold conditions. Further, biodiesel has low

volumetric heating values (about 12%), a high cetane number and a high flash point.

The cloud points and flash points of biodiesel are 1525OC higher than those of

diesel.

Process of biodiesel production

Simple transesterification reaction

Transesterification of vegetable oils with simple alcohol has long been the preferred

method for producing biodiesel. It is preferred to have ethanol, as it is a bio-origin

fuel. In general, there are two methods of transesterification.

One method simply uses a catalyst and the other is without a catalyst. The former

method has a long history of development and the biodiesel produced by this method

is now available in North America, Japan and some western European countries.

Chemistry of transesterification reaction:

O

----COCH2

O O HO CH2

-----COCH + 3 CH3OH 3- - - - -COCH3 + HO CH

O

(Methanol ) ( Methyl ester)

-----COCH2 (biodiesel) HO CH2

(Tri acyl-glycerol (Glycerol)

or vegetable oil)


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The overall transesterification reaction is given by three consecutive and reversible;

the first step is the conversion of triglycerides to diglycerides, followed by the

conversion of diglycerides to monoglycerides, and of monoglycerides to glycerol,

yielding one methyl ester molecule per mole of glyceride at each step. During

methanolysis, two distinct phases are present as the solubility of the oil in methanol is

low and the reaction mixture needs vigorous stirring. Optimum reaction conditions

for the maximum yield of methyl esters have been reported to be 0.8% (based on

weight of oil) potassium hydroxide catalyst and 100% excess methanol at room

temperature for 2.5 h. Glycerol phase separation does not occur when


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Process variables:

The most important variables that influence the transesterification reaction are:

! Reaction temperature.

! Ratio of alcohol to vegetable oil.

! Catalyst.

! Mixing intensity.

! Purity of reactants.

Reaction temperature:

The literature has revealed that the rate of reaction is strongly influenced by the

reaction temperature. However, the reaction is conducted close to the boiling point of

methanol (6070OC) at atmospheric pressure for a given time. Such mild reaction

conditions require the removal of free fatty acids from the oil by refining or pre-

esterification. Therefore, degummed and deacidified oil is used as feedstock.

Pretreatment is not required if the reaction is carried out under high pressure (9000

kPa) and high temperature (240OC), where simultaneous esterification and

transesterification take place with maximum yield obtained at temperatures ranging

from 60 to 80OC at a molar ratio of 6:1.


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31

Ratio of alcohol to oil

Another important variable is the molar ratio of alcohol to vegetable oil. As indicated

earlier, the transesterification reaction requires 3 mol of alcohol per mole of

triglyceride to give 3 mol of fatty esters and 1 mol of glycerol. In order to shift the

reaction to the right, it is necessary to either use excess alcohol or remove one of the

products from the reaction mixture. The second option is usually preferred for the

reaction to proceed to completion. The reaction rate was found to be highest when

100% excess methanol was used. A molar ratio of 6:1 is normally used in industrial

processes to obtain methyl ester yields higher than 98% (w/w) .

Catalysts

Alkali metal alkoxides are found to be more effective transesterification catalysts

compared to acidic catalysts. Sodium alkoxides are the most efficient catalysts,

although KOH and NaOH can also be used. Transmethylation occurs in the presence

of both alkaline and acidic catalysts. As they are less corrosive to industrial

equipment, alkaline catalysts are preferred in industrial processes. A concentration in

the range of 0.51% (w/w) has been found to yield 9499% conversion to vegetable

oil esters, and further increase in catalyst concentration does not affect the conversion

but adds to extra cost, as the catalyst needs to be removed from the reaction mixture

after completion of the reaction.

Mixing intensity

It has been observed that during the transesterification reaction, the reactants initially

form a two-phase liquid system. The mixing effect has been found to play a

significant role in the slow rate of the reaction. As phase separation ceases, mixing

becomes insignificant. The effect of mixing on the kinetics of the transesterification

process forms the basis for process scale-up and design.

Purity of reactants

Impurities in the oil affect the conversion level considerably. It is reported that about

6584% conversion into esters using crude vegetable oils has been obtained as

compared to 9497% yields refined oil under the same reaction conditions . The free

fatty acids in the crude oils have been found to interfere with the catalyst. This


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32

problem can be solved if the reaction is carried out under high temperature and

pressure conditions.

Supercritical methanol transesterification

The simple transesterification process discussed above is confronted with two

problems, i.e. the process is relatively time consuming and it needs separation of the

catalyst and saponified impurities from the biodiesel. The first problem is due to the

phase separation of the vegetable oil/methanol mixture, which may be dealt with by

vigorous stirring. These problems are not faced in the supercritical methanol method

of transesterification. This is perhaps due to the fact that the tendency of two-phase

formation of vegetable oil/methanol mixture is not encountered and a single phase is

found due to decrease in the dielectric constant of methanol in the supercritical state.

As a result, the reaction was found to be complete in a very short time within 24

min. Further, since no catalyst is used, the purification on biodiesel is much easier,

trouble free and environment friendly. The result of transesterification of rapeseed oil

in the supercritical methanol method has indicated that at temperature of 239OC and

pressure of 8.09 MPa, glycerol and methyl esters are obtained as the principal

products.

Performance of conventional diesel engines with Biodiesel

Conventional Compression Ignition engines can be operated with biodiesel without

major modifications. In comparison to diesel, the higher cetane number of biodiesel

results in shorter ignition delay and longer combustion duration and hence results in

low particulate emissions and minimum carbon deposits on injector nozzles. It is

reported that if an engine is operated on biodiesel for a long time, the injection timing

may be required to be readjusted for achieving better thermal efficiency. Various

blends of biodiesel with diesel have been tried, but B-20 has been found to be the

most appropriate blend. Further studies have revealed that biodiesel blends lead to a

reduction in smoke opacity, and emission of particulates, unburnt hydrocarbons,

carbon dioxide and carbon monoxide, but cause slightly increase in nitrous oxide

emissions . It is noteworthy that all the blends have a higher thermal efficiency than

diesel and so give improved performance.


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Environmental considerations:

In view of environmental considerations, biodiesel is considered carbon neutral

because all the carbon dioxide released during consumption had been sequestered

from the atmosphere for the growth of vegetable oil crops. Studies have shown that

the combustion of 1litre of diesel fuel leads to the emission of about 2.6 kg of CO 2

against 1 kg ofCO2/kg of biodiesel, so the use of biodiesel may directly displace this

amount ofCO2 when used in engines. The combustion of biodiesel has been reported

to emit lesser pollutants compared to diesel. The NOX emissions are reported to be in

the range between 10% as compared to diesel depending on engines combustion

characteristics. The reduction in NOX has been reported by incorporating EGR

technique.

Economic feasibility of biodiesel

India has rich and abundant resources of edible and non-edible oilseeds, the

production of which can be stepped up manifolds if the government provides

incentives to farmers for production of biodiesel. The economic feasibility of

biodiesel depends on the price of crude petroleum and the cost of transporting diesel

over long distances to remote areas. It is a fact that the cost of diesel will increase in

future owing to the increase in its demand and limited supply. Further, the strict

regulations on the aromatic and sulfur contents of diesel fuels will make diesel

costlier, as the removal of aromatics from distillate fractions needs costly processing

equipment and continuous high operational cost as large amounts.

Currently, the production of methyl or ethyl esters from edible oils is much more

expensive than that of diesel fuels due to the relatively high costs of vegetable oils

(about four times the cost of diesel in India). Methyl esters produced from such oils

cannot compete economically with diesel fuels unless they are granted protection

from tax levies. Under such conditions, there is a need to explore alternate feedstocks

for the production of biodiesel. An economic analysis for the production of biodiesel

using different types of edible and non-edible oils was reported by Barnwal et al.,

2005. At present the cost of biodiesel could be higher, the cost can be reduced if we

consider non-edible oils, used frying oils and acid oils instead of edible oils. Non-


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34

edible oils from sources such as neem, mahua, pongamia, karanji, babassu, jatropha,

etc. are easily available in many parts of the world including India, and are very

cheap compared to edible oils. With the mushrooming of fast food centers and

restaurants in India, it is expected that considerable amounts of used frying oil will be

discarded which can be diverted for biodiesel production, and thus may help reduce

the cost of water treatment in the sewerage system and assisting in the recycling of

resources.

Amba Prasad et al., 2003 did experimental investigations on a conventional DI and

IDI type diesel engines with untreated Jatropha oil and its methyl esters under

following conditions:

Direct Injection Engine

Effect of Injection Pressure on the use of Untreated Jatropha oil

Effect of Injection Pressure and Supercharge Pressure on the use of untreated

Jatropha oil

Use of Methyl esters of Jatropha oil(Biodiesel)-NA condition

Use of Biodiesel-SC condition

LHR concept

Indirect Injection Engine

Effect of Injection Pressure on the use of Untreated Jatropha oil

Use of Methyl esters of Jatropha oil(Biodiesel)-NA condition.


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Fig.2. Variation of bsfc with IP under full load condition

0.25

0.27

0.29

0.31

0.33

0.35

0.37

0.39

160 180 200 220 240

Injection Pressure,bar

bsfc,kg/kWh

NA

SC 0.2 bar(g)

SC 0.3 bar(g)

SC 0.4 bar(g)

Fig. 1. Variation of bsfc with bmep under NA condition

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 1 2 3 4 5 6

bmep,bar

bsfc,kg/kWh

UJ0,IP 180 bar

UJO,IP 210 bar

UJO,IP 240 bar

Baseline


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Fig.5. Variation of bsec with bmep for three fuels at RIP

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5 6bmep, bar

bs

ec,kW/kW

Baseline

UJO

Biodiesel

Fig.3. Variation of smoke density with bmep

0

10

20

30

40

50

60

70

80

0 1 2 3 4 5 6

BMEP, bar

Smokedensity,HSU

UJO RIP

Baseline

UJO SC 0.2 bar(g)

UJO SC 0.3 bar(g)

UJO SC 0.4 bar(g)


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Fig.6. Variation of smoke density with bmep

0

5

10

15

20

25

30

35

40

0 2 4 6

bmep,bar

Smokedens

ity,HSU

Biodiesel NA

Biodiesel SC 0.2

bar(g)

Fig.7. Variation ofbsfc with bmep

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 1 2 3 4 5 6

bmep,bar

Conventional

Coated

Fig.8. Variation of volumetric efficiency with bmep

50

60

70

80

90

100

0 1 2 3 4 5 6

bmep,bar

Volumetricefficiency,%

Baseline

Conventional

Coated


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Fig. . Comparison of NOx emissions of DI&IDI Engines under full

load operation

0200

400

600

800

1000

1200

1400

DID

iese

l

DIB

iodiesel

DIB

iodiesel+S

C

DIL

HRBiodiesel

IDID

iese

l

IDIB

iodies

el

Type of engine and fuel

NOX,ppm

Fig. Comparison of bsfc of DI and IDI engines

0.2

0.3

0.4

0.5

0.6

0.7

0 20 40 60 80 100

%Full power bmep

bsfc,kg/kWh

DI SC 0.2 bar(g)

IDI NA


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Important Conclusions:

Biofuels (Biodiesel) hold great promise as substitutes of diesel in existing

diesel engines without any modification. The partial or full replacement of

diesel with biodiesel will relieve the pressure on existing diesel oil resources

as well as conserve a lot of diesel fuel, thereby saving substantial money.

Non-edible oils find great promise as biodiesel, and hence there is a need to

grow high yielding non-edible oil seed crops on arable and non-arable lands.

DI Engine

bsfc as well as smoke levels are lower when untreated Jatropha oil is used ina DI engine, at an injection pressure 20% higher than the recommendedinjection pressure for diesel-fuel operation.

Peak pressures obtained with untreated Jatropha oil (little lower) arecomparable to that of diesel-fuel operation and low rates of pressures are

obtained in spite of low cetane number of Jatropha oil.

Injector choking and fuel filter clogging are encountered with untreatedJatropha oil.

Dual benefit of fuel economy and low smoke are achieved by employingsupercharging with untreated Jatropha oil operation.

Increasing the injection pressure while maintaining the boost pressureconstant does not improve the performance of the engine.

Transesterification reduces the viscosity by about 88% and density by 4.34%.

Biodiesel operation reduces the smoke density by about 45% at full load

compared to untreated Jatropha oil operation under naturally aspiratedcondition.

Brake Specific Energy Consumption values are lower with biodieselcompared to diesel fuel operation.

Supercharged operation of the engine with biodiesel brings the performance

very close to diesel fuel operation.

Gummy deposits on important engine components are reduced with biodiesel

operation.

Lower smoke levels and higher NOX levels are obtained in DI engine withbiodiesel.


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Higherbsfc and higher smoke levels are observed during 50-100% load rangewhen biodiesel is employed in LHR engine.

At full load about 8% saving in coolant load is achieved with LHR approachwhile running on biodiesel.

Exhaust energy recovery increases in LHR approach when engine is run with

biodiesel under NA condition.

Lube oil temperatures increase in LHR engine under biodiesel operation andnecessitate the use of better quality lubricants.

50/50 blend of biodiesel and diesel leads to lower bsfc when compared to100% biodiesel operation under NA condition.

IDI Engine

Owing to its pre-chamber design the IDI engine accommodates untreatedJatropha oil at lower injection pressure compared to DI engine.

bsfc as well as smoke levels are lower when untreated Jatropha oil is used inIDI engine, at an injection pressure 10% higher than the recommended

injection pressure for diesel-fuel operation.

Smoke density is lower in IDI engine compared to DI engine while operatingon untreated Jatropha oil.

Untreated Jatropha oil operation leads to deterioration of the fuel injectionequipment.

Biodiesel operation not only improves the performance but also tremendouslyreduces the gummy deposits.

As far as bsfc is concerned, DI engine exhibits superior performance

compared to IDI engine.

Lower smoke levels and higher NOX levels are obtained in IDI engine withbiodiesel.


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Table-1: Properties of selected Alternative Fuels compared to Gasoline and Diesel Fuel

Fuel property Methanol Ethanol Gasoline No.2 Diesel fuel Natural

gas(Metha

ne)

Hydro

Formula CH3OH C2H5OH C4-C12 C8-C25 CH4 H2Mol.wt. 32.04 100-105 200(approx) 16 2.02

Composition(wt %Carbon

HydrogenOxygen

37.512.649.9

52.213.134.7

85- 8812-150-4

84-8713-160

75250

01000

Density, kg/l, @15OC 0.796 0.79 0.69-0.79 0.81-0.89 0.001

Freezing point, deg C -97.5 -114 -40 -40 to -1 -182 -275

Boiling point, degC 65 78 27-225 188-343 162 -253

Vapor Pressure, kPa@38

OC

32 15.9 48-103 < 1 Notavailable

Notavaila

Specific heat, kJ/kg-K 2.5 2.4 2.0 1.8 -- 14.2

Viscosity,mPa-s @20OC

0.59 1.19 0.37-0.44 2.6-4.1 0.01 0.009

Water solubility,21

OC,water in fuel Vol %

100 100 Negligible Negligible Negligible Neglig

Electrical conductivity,

mhos/cm

4.4.10-7

1.35.10-9

1.10-14

1.10-12

-- --

Latent heat of

vaporization, kJ/kg

1178 923 349 233 510 448

Lower Heating value,

1000kJ/l

15.8 21.1 30-33 35-37 8.4

Flash Point, deg C 11 13 -43 74 -188 -

Auto ignition

temperature, degC

464 423 257 316 540 -

Flammability limits, vol%Lower

Higher 7.336.0

4.319.0

1.47.6

1.06.0

515

475

Stoichiometric air-fuelratio, wt

6.45 9.00 14.7 14.7 17.2 34.3

Flame spread rate, m/s 2-4 4-6 - Not

applicable

-

Flame visibility Invisible in day light Difficult to see

in daylight

Visible in all

conditions

Visible in all

conditions

Visible in

all

conditions

Invisi

in d

sunlig

Octane Number

ResearchMotor

108.788.6

108.689.7

88-10080-90

--

Estimated

120120

----

Cetane Number -- -- 0 40-55

Adiabatic FlameTemperature (K)

2151 2197 2266 2227 2383

Stoichiometric CO2

emissionsg CO2/MJfuel

69 71.2 71.9 54.9 0


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References:

1. Richard L. Bechtold 1997, Alternative Fuels Guide Book SAE

Publications.

2. Barnwal, B.K, and Sharma, M.P., 2005 Prospects of Biodiesel

Production from vegetable oils in India Renewable and Sustainable

Energy Reviews Vol.5 pp:363-378.

3. Avinash Kumar Agarwal 2007 Biofuels (Alcohols and Biodiesel)

applications as fuels for internal combustion engines Progress in

Energy and Combustion Science Vol.33 pp:233-271.

4. Pramanik. K., 2003 Properties and use of Jatropha curcas oil and

diesel fuel blends in compression ignition engine Renewable Energy

Vol.28 pp:239-248.

5. Ayhan Dermibas 2007 Progress and Recent Trends in Biofuels

Progress in Energy and Combustion Science Vol.33 pp:1-18.

6. Borman,G.L., and Ragland. K.W., 1998 Combustion Engineering

Mc.Graw-Hill Publications.

7. Heywood .J.B., 1988 Internal Combustion Engine Fundamentals

Mc.Graw-Hill Publications.

8. N.Vijaya Raju, G.Amba Prasad Rao and P.Rama Mohan 2000

Esterfied Jatropha oil as a fuel in diesel engines pp 65-75 Proceedings

of XVI National Conference on IC Engines and Combustion

(NCICEC) Jadavpur University ,Calcutta, January 20-22 .

9. G.Amba Prasad Rao and P.Rama Mohan, 2003 Effect of

supercharging on the performance of a DI diesel engine with

vegetable oils Intl. Jrl. of Energy Conversion and Management, pp

937-944 vol.44 no.6 Apr.2003.10. G.Amba Prasad Rao and P.Rama Mohan 2005 Performance

Evaluation of DI and IDI engines with Jatropha oil based Biodiesel

Vol.86, pp 72- 76 July , Journal of The Institution of Engineers (India).

Documents

Renewable Fuels for Transportation-Amba Prasad