IC Engine Unit 4 ALTERNATE FUELS.ppt

UNIT IV
ALTERNATE FUELS
• Alcohol, Hydrogen, Compressed
Natural Gas, Liquefied
Petroleum Gas and Bio Diesel -
Properties, Suitability, Merits
and Demerits -Engine
Modifications.

SOLID FUELS
Solid fuels are obsolete for IC engines. In order to have historical
perspective we will describe some of the earlier attempts. In the latter half
of the 1800s, before petroleum-based fuels were perfected, many other
fuels were tested and used in IC engines. When Rudolf Diesel was
developing his engine, one of the fuels he used was a coal dust mixed with
water. Fine particles of coal (carbon) were dispersed in water and injected
and burned in early diesel engines.
LIQUID FUELS
Liquid fuels are preferred for IC engines because they are easy to store
and have reasonably good calorific value. In the liquid fuel category the
main alternative is the alcohol.

Alternative fuels, known as non-conventional or advanced fuels, are any
materials or substances that can be used as fuels, other than
conventional fuels.
Conventional fuels include: fossil fuels (petroleum (oil), coal, propane,
and natural gas), as well as nuclear materials such as uranium and
thorium, as well as artificial radioisotope fuels that are made in nuclear
reactors.
Types:
• Alcohols
• Vegetable oils
• Bio-diesel
• Bio-gas
• Natural Gas
• Liquefied Petroleum Gas
• Hydrogen

Alcohol as Fuel in IC Engine
• Alcohol is of organic origin and can be produced from a wide range of abundantly available
raw materials. Ethanol (C2H5OH) can be produced by fermentation of carbohydrates which
occur naturally and abundantly in some plants like sugarcane and can also be produced
from starchy materials like corn, potatoes, maize and barley.
• The starchy material is first converted into sugar which is then fermented by yeast. For the
large-scale production of methanol (CH3OH), the following methods are commonly
employed:
a) Destructive distillation of wood,
b) Synthesis from water gas,
c) From natural gas but it is petroleum based,
d) From coal, a relatively abundant fossil fuel.
• Alcohols have high antiknock characteristics which permit spark-ignition engines to run at
higher compression ratios.
• A lean mixture will burn and the exhaust gas temperature will be lower.
• Alcohols, therefore, will reduce CO and NOx in the exhaust. The alcohol fuelled SI engines
can produce a slightly higher power output.

The physical properties of methanol, ethanol and gasoline

Alcohol
Alcohols are an attractive alternate fuel because they can be obtained from
both natural and manufactured sources. Methanol (methyl alcohol) and
ethanol (ethyl alcohol) are two kinds of alcohols that seem most promising.
The advantages of alcohol as a fuel are:
• It can be obtained from a number of sources, both natural and
manufactured.
• It is a high octane fuel with anti-knock index numbers (octane number) of
over 100. Engines using high-octane fuel can run more efficient by using
higher compression ratios. Alcohols have higher flame speed.
• It produces less overall emissions when compared with gasoline.
• When alcohols are burned, it forms more moles of exhaust gases, which
gives higher pressure and more power in the expansion stroke.
• It has high latent heat of vapourization (hfg ) which results in a cooler
intake process. This raises the volumetric efficiency of the engine and
reduces the required work input in the compression stroke.
• Alcohols have low sulphur content in the fuel.

The disadvantages of alcohol as a fuel are:
• Alcohols have a low energy content or in other words the calorific value
of the fuel is almost half. This means that almost twice as much alcohol
as gasoline must be burned to give the same energy input to the engine.
With equal thermal efficiency and similar engine output usage, twice as
much fuel would have to be purchased, and the distance which could be
driven with a given fuel tank volume would be cut in half. Automobiles as
well as distribution stations would require twice as much storage
capacity, twice the number of storage facilities, twice the volume of
storage at the service station, twice as many tank trucks and pipelines,
etc. Even with the lower energy content of alcohol, engine power for a
given displacement would be about the same. This is because of the
lower air-fuel ratio needed by alcohol. Alcohol contains oxygen and thus
requires less air for stoichiometric combustion. More fuel can be burned
with the same amount of air.
• Combustion of alcohols produce more aldehydes in the exhaust. If as
much alcohol fuel was consumed as gasoline, aldehyde emissions would
be a serious exhaust pollution problem.

• Alcohol is much more corrosive than gasoline on copper, brass,
aluminum, rubber, and many plastics. This puts some restrictions on the
design and manufacturing of engines to be used with this fuel. Fuel lines
and tanks, gaskets, and even metal engine parts can deteriorate with
long-term, alcohol use (resulting in cracked fuel lines, the need for special
fuel tank, etc).Methanol is very corrosive on metals.
• It has poor cold weather starting characteristics due to low vapour
pressure and evaporation. Alcohol-fuelled engines generally have
difficulty in starting at temperatures below 10 °C. Often a small amount of
gasoline is added to alcohol fuel, which greatly improves cold-weather
starting. The need to do this, however, greatly reduces the attractiveness
of any alternate fuel.
• Alcohols have poor ignition characteristics in general.
• Alcohols have almost invisible flames, which are considered dangerous
when handling fuel. Again, a small amount of gasoline removes this
danger.

Disadvantages:
• It has low energy content ( low calorific values almost half the value), which means to
give the same energy input to the engine twice the amount of fuel is required.
• Combustion produces more aldehyde emissions
• Susceptible to more corrosion on copper, brass, aluminum
• Generally poor ignition characteristics – cold weather starting due to low vapour pressure
and evaporation.
• Handling of alcohol is dangerous as it has invisible flame.
• Due to low vapour pressure, there is a danger of danger of storage tank flammability ( Air
can leak into storage tank and create a combustible mixture.
• Possibility of vapour lock in the fuel delivery system
• Strong odour of alcohol gives head ache, dizziness when refueling.

 There is the danger of storage tank flammability due to low vapour pressure. Air
can leak into storage tanks and create a combustible mixture.
 Because of low flame temperatures there will be less NOx emissions but the
resulting lower exhaust temperatures take longer time to heat the catalytic
converter to an efficient operating temperature.
 Many people find the strong odour of alcohol very offensive. Headaches and
dizziness have been experienced when refuelling an automobile.
 There is a possibility of vapour lock in fuel delivery systems.

Of all the fuels being considered as an alternate to gasoline, methanol is one of the
most promising and has experienced major research and development. Pure
methanol and mixtures of methanol and gasoline in various percentages have been
extensively tested in engines and vehicles for a number of years.
The most common mixtures are .
• M85 (85% methanol and 15% gasoline) and MI0 (10% methanol and 90%
gasoline). The data of these tests which include performance and emission levels
are compared to pure gasoline (MO) and pure methanol (MI00). Some smart
flexible fuel (or variable-fuel) engines are capable of using any random mixture
combination of methanol and gasoline ranging from pure methanol to pure
gasoline. Two fuel tanks are used and various flow rates of the two fuels can be
pumped to the engine, passing through a mixing chamber. Using information
from sensors in the intake and exhaust, the electronic monitoring system (EMS)
adjusts to the proper air-fuel ratio, ignition timing injection timing, and valve
timing (where possible) for the fuel mixture being used.

 One problem with gasoline-alcohol mixtures as a fuel is the tendency for alcohol to
combine with any water present. When this happens the alcohol separates locally from
the gasoline, resulting in a non homogeneous mixture. This causes the engine to run
erratically due to the large air-fuel ratio differences between the two fuels.
 Methanol can be obtained from many sources, both fossil and renewable. These include
coal, petroleum, natural gas, biomass, wood, landfills, and even the ocean. However, any
source that requires extensive manufacturing or processing raises the price of the fuel.
 Emissions from an engine using M10 fuel are about the same as those using gasoline.
The advantage (and disadvantage) of using this fuel is mainly the 10% decrease in
gasoline use. With M85 fuel there is a measurable decrease in HC and CO exhaust
emissions. However, there is an increase in NOx and a large increase in formaldehyde
formation.
 Methanol is used in some dual-fuel CI engines. Methanol by Itself is not a good CI fuel
because of its high octane number, but if a small amount of diesel oil is used for ignition,
it can be used with good results. This is very attractive for developing countries because
methanol can often be obtained from much cheaper source than diesel oil.

 Ethanol has been used as automobile fuel for many years in various regions of
the world. Brazil is probably the leading user, where in the early 1990s. About 5
million vehicles operated on fuels that were 93% ethanol. For a number of years
gasohol (gasoline +. alcohol) has been available at service stations in the United
States.
 Gasohol is a mixture of 90% gasoline and 10% ethanol. As with methanol the
development of systems using mixtures of gasoline and ethanol continues. Two
mixture combinations that are important are E85 (85% ethanol) and E10
(gasohol).
 E85 is basically an alcohol fuel with 15% gasoline added to eliminate some of
the problems of pure alcohol (i.e., cold starting, tank flammability, etc.). E10
reduces the use of gasoline with no modification needed to the automobile
engine. Flexible-fuel engines are being tested which can operate on any-ratio of
ethanol-gasoline.

ETHANOL
 CH3CH2OH
 Ethanol is a clean-burning, high-octane fuel that is produced from
renewable sources.
 At its most basic, ethanol is grain alcohol, produced from crops such
as corn.
 Since pure 100% ethanol is not generally used as a motor fuel, a
percentage of ethanol is combined with unleaded gasoline, to form
E10 and E85
 E10: 10% ethanol and 90% unleaded gasoline, is approved for use
in any US vehicle
 E85: 85% ethanol and 15% unleaded gasoline, is an alternative fuel
for use in flexible fuel vehicles (FFVs).

 Ethanol can also be produced from "cellulosic biomass" such as trees and
grasses and is called bio ethanol. Ethanol is most commonly used to increase
octane and improve the emissions quality of gasoline.
 Ethanol can be made by fermenting almost any material that contains starch.
 Most of the ethanol is made using a dry mill process.
 In the dry mill process, the starch portion of the corn is fermented into sugar
then distilled into alcohol
 Ethanol can be made from ethylene or from fermentation of grains and sugar.
Much of it is made from corn, sugar beets, sugar cane and even cellulose (wood
and paper). The present cost of ethanol is high due to the manufacturing and
processing required. This would be reduced if larger amounts of this fuel were
used. Ethanol has less HC emissions than gasoline but more than methanol.

» High octane (100+); enhances octane properties of gasoline and
used as oxygenate to reduce CO emissions.
» 27% - 36% less energy content than gasoline. OEM’s estimate
15% - 30% decrease in mileage.
» E85 vehicles demonstrate a 25% reduction in ozone-forming
emissions compared to gasoline.
» As an alternative fuel, most commonly used in a blend of 85%
ethanol and 15% gasoline (E85).

» Mostly used in light-duty vehicles called flexible fuel vehicles
(FFVs). FFVs can use 100% unleaded fuel or any mixture of
E85 and unleaded fuel.
» Several manufacturers offer FFVs in car and pickup
configurations.

» Decreased mileage.
» High level of fuel pricing volatility until demand and supply
balance.
» Refueling infrastructure not in place in all areas
» Ongoing debate: energy balance, land mass, food vs. fuel, and
water required.

IMPACT ON AIR QUALITY
 Using ethanol-blended fuel has a positive impact on air quality. By adding
oxygen to the combustion process which reduces exhaust emissions—
resulting in a cleaner fuel for cleaner air.
 Ethanol reduces the emissions of carbon monoxide, VOX, and toxic air
emissions:
 Since ethanol is an alcohol based product, it does not produce
hydrocarbons when being burned or during evaporation thus decreasing
the rate of ground level ozone formation.
 Ethanol reduces pollution through the volumetric displacement of
gasoline. The use of ethanol results in reductions in every pollutant
regulated by the EPA, including ozone, air toxins, carbon monoxide,
particulate matter, and NOX.

PROBLEMS WITH ETHANOL
 Odors as a public nuisance
 Green house gas emissions have sometimes shown to be equivalent to
those of gasoline (data is often inconclusive)
 Environmental performance of ethanol varies greatly depending on the
production process
 Costs involved with building new facilities for ethanol production
 New ways to maximize crop production are necessary
 Research is needed to refine the chemical processes to separate, purify and
transform biomass into usable fuel

• Methanol is considered to be one of the most likely alternative automotive fuels.
However, several major technical difficulties must be resolved before 100 % methanol
can become a commercially acceptable fuel for use in vehicles.
• The most commonly mentioned difficulties are cold start (no start below 15°C), safety
(explosive mixture in the fuel tanks, invisible flame), and corrosion and wear of engine
and fuel system materials.
• In addition, the vehicle range (distance covered) will also be reduced substantially,
unless the size of the fuel tank is greatly increased, because the volumetric energy
density of methanol is only about one-half of that of gasoline.
• Most of these problems may be resolved by using a medium concentration (30-70 % by
volume) blend of methanol and gasoline. However, the use of such blends may
compromise some of methanol's key NOx emissions.

• As it has high anti knock characteristics compared to gasoline it used in engines having
compression ratio between11:1 and 13:1
• It produces lesser emission( less heat energy)
• Stoichiometric air fuel ratio is lesser for alcohol. Hence to provide a proper fuel air
mixture , fuel passage area (carburetor / fuel injector) needs to be doubled for providing
the extra fuel flow.
• As it has high latent heat of vaporization it does not vaporize easily, which has impact in
cold starting. Hence at extreme cold condition gasoline to be introduced till the engine
start and warm up
• At normal operating condition preheating required to completely vaporize alcohol.
• Alcohol burns at half the speed of gasoline hence the ignition timing must be
changed(Spark advance to be provided). This gives the slow burning alcohol to develop
more pressure and power in the cylinder
• Corrosion resistant material to be used in the fuel system.
ALCOHOL FOR SI ENGINE

 Alcohols have higher antiknock characteristic compared to gasoline. As such
with an alcohol fuel, engine compression ratios of between 11:1 and 13:1 are
usual. Today's gasoline engines use a compression ratio of around 7:1 or 9:1,
much too low for pure alcohol.
 In a properly designed engine and fuel system, alcohol produces fewer harmful
exhaust emissions. Alcohol contains about half the heat energy of gasoline per
litre. The stoichiometric air fuel ratio is lesser for alcohol than for gasoline. To
provide a proper fuel air mixture, a carburetor or fuel injector fuel passages
should be doubled in area to allow extra fuel flow. Alcohol does not vapourize
as easily as gasoline. Its latent heat of vapourization is much greater. This
affects cold weather starting.

 Alcohol liquefies in the engine and will not burn properly. Thus, the engine may
be difficult or even impossible to start in extremely cold climate. To overcome
this, gasoline is introduced in the engine until the engine starts and warms up.
Once the engine warms, alcohol when introduced will vapourize quickly and
completely and burn normally.
 Even during normal operation, additional heat may have to be supplied to
completely vapourize alcohol. Alcohol burns at about half the speed of gasoline.
As such, ignition timing must be changed, so that more spark advance is
provided. This will give the low buring alcohol more time to develop the
pressure and power m the cylinder. Moreover, corrosion resistant materials are
required for fuel system since alcohols are corrosive in nature.

Techniques of using alcohol in diesel engines are
 Alcohol/diesel fuel solutions
 Alcohol diesel emulsions.
 Alcohol fumigation
 Dual fuel injection
 Surface ignition of alcohols.
 Spark ignition of alcohols
 Alcohols containing ignition improving additives.
ALCOHOL FOR CI ENGINES

 Both ethyl and methyl alcohols have high self ignition temperatures.
Hence, very high compression ratios (25-27) will be required to self
ignite them. Since this would make the engine extremely heavy and
expensive, the better method is to utilize them in dual fuel operation.
 In the dual fuel engine, alcohol is carburetted or injected into the
inducted air. Due to high self ignition temperature of alcohols there will
be no combustion with the usual diesel compression ratios of 16 to 18. A
little before the end of compression stroke, a small quantity of diesel oil
is injected into the combustion chamber through the normal diesel pump
and spray nozzle. The diesel oil readily ignites and this initiates
combustion in the alcohol air mixture also.

 Several methods are adopted for induction of alcohol into the
intake manifold. They are micro fog unit, pneumatic spray
nozzle, vaporizer, carburettor and fuel injector. The degree of
fineness in mixing of fuel and air are different for the above
methods.
 Another method tried is to inject alcohol into the combustion
chamber after the diesel fuel injection: This way of alcohol
injection avoids the alcohol cooling the charge in the cylinder to
a degree which will jeopardise the ignition of the diesel fuel.
However, this design calls for two complete and separate fuel
systems with tank, fuel pump, injection pump and injectors.

• Alcohol will be used as Dual fuel in CI engines. As alcohol has high self ignition
temperature, for normal compression ratio between 16 to 18 the combustion will not
initiate. Hence at the end of compression stroke a pilot injection of diesel into the
combustion chamber would be required. This pilot injection will start the combustion
process.
• As the diesel is only used for pilot injection, major amount of heat is released only by
Alcohol. The performance is influenced by the following properties:
• The Calorific value of alcohol is lower than diesel hence large quantity of alcohol is
required to produce the same power.
• Since the air requirement is low energy content will be same as that of gasoline.
• The temperature and pressure at the end compression comes down as the high
latent heat of vaporisation.
• Excess induction of alcohol into the combustion chamber will not allow the diesel to
ignite.
ALCOHOL FOR CI ENGINE

 In the dual fuel engines mentioned above, major portion of the heat release is by
the alcohol supplied and this alcohol is ignited by a pilot spray of diesel oil
injection. The performance of the dual fuel engine is influenced by the following
properties of alcohols:
 The calorific value of alcohols is lower than diesel oil and hence a larger quantity
of alcohol has to be used for producing the same amount of power output.
However, their air requirement for combustion is lower, and hence the energy
content of the mixture is roughly the same. Since their latent heat of
vapourization is very high, the temperature and pressure at the end of
compression come down due to their evaporation. Hence, if the alcohol induction
rate exceeds a limit, the injected diesel will not be able to ignite and hence the
engine will fail to function.
 All the dual fuel systems described above have the basic disadvantage of
requiring two different types of fuels and associated components. Since alcohols
have a high tendency to pre-ignite in SI engines, recently, this property was made
use of in a compression ignition engine by using a hot surface to initiate ignition.

 The surface-ignition plug mounted on an alcohol fuelled direct injection diesel
engine can be seen in Fig
SURFACE-IGNITION ALCOHOL CI ENGINE

 A slab of insulator material, wound with a few strands of heating wire (kanthal
heating element wire) is fixed on the combustion chamber with the wire running
on the face exposed to the gases. The fuel injector is located such that a part of
the spray impinges head on this surface. Ignition is thus initiated.
 The combustion chamber, which is in the cylinder head, is made relatively
narrow so that the combustion spreads quickly to the rest of the space. Since a
part of the fuel burns on the insulator surface and since the heat losses from the
plate are low, the surface after some minutes of operation reaches a temperature
sufficient to initiate ignition without the aid of external electrical supply.
 The power consumption of the coil is about 50 W at 6 volts. The engine lends
itself easily to the use of wide variety of fuels, including methanol, ethanol and
gasoline. The engine was found to run smoothly on methanol with a performance
comparable to diesel operation. The engine operates more smoothly at lower
speeds than at higher speeds.
SURFACE-IGNITION ALCOHOL CI ENGINE

Hydrogen as Fuel in IC Engine
• With the imposition of stringent emission standards along with the decreasing availability of
petroleum products, it is imperative that a search for low polluting alternative fuels be
made.
• Hydrogen, as an SI engine fuel acquires special significance in view of its unlimited supply
potential and almost non-polluting characteristics.
• Even though with current economics hydrogen would be a costly automotive fuel, based
on long-term considerations, its relative cost standing may improve considerably.
• As and when a cheaper method of hydrogen production becomes available, it could be
used for aircraft, marine vessels, railways and automotive vehicles.
• Hydrogen has emerged as a potential fuel for internal combustion engines. It is generally
considered to be non-polluting because hydrogen contains no carbon.
• Species such as carbon monoxide and unburned hydrocarbons, which are normally found
in gasoline fueled engines, would be virtually eliminated in the exhaust.
• Hydrogen is found in abundant quantities in various forms and can be considered to be an
almost inexhaustible fuel.
• It can be adapted as a fuel to engines without major design changes.

• The problems generally experienced in a hydrogen-fueled engine are the
backfiring, pre-ignition, knocking and rapid rate of pressure rise during the
combustion process because of the higher flame speed.
• Backfiring is mainly due to less ignition energy for a hydrogen-air mixture
Localized hot points in the chamber and the temperature of the residual gas
are sometimes sufficient to cause backfiring.
• Hydrogen-fuelled engines can be run at a much leaner equivalence ratio than a
gasoline-fuelled engine, although lean operations of hydrogen-fuelled engine
generally reduce NO emissions and show improved thermal efficiency.
• Problems associated with too lean mixtures increase the ignition delay and
cause severe cyclic variations.
• The hydrogen peroxide is present in the exhaust products of a hydrogen-
fuelled engine operating with very lean mixtures.

• Compared with hydrocarbon fuels, hydrogen has certain advantages due to its high
chemical reactivity: (a) a higher flame propagation speed, (b) wider ignition limits, and (c)
lower ignition energy.
• The high flame propagation speed of hydrogen certainly benefits the thermodynamic
efficiency of the engine as the combustion process is closer to the optimum theoretical
combustion at constant volume.
• The wider ignition limits provide the possibility to run with extremely lean mixtures. A lower
ignition energy is favourable for ignition of lean mixtures in SI engines, but has the
disadvantage of resulting in abnormal combustion (knock and surface ignition), especially
near stoichiometry.
• Because backfire must be avoided at all costs, it is necessary to avoid knock and surface
ignition. This can be done by leaning the mixture.
• Since this reduces the available power, its use should be limited. Knocking and the rate of
pressure rise can also be controlled by increasing the flame travel distance.
• This can be done by locating the spark plug near the periphery, away from the centre of the
cylinder head.

• On-board storage of hydrogen remains a major technical challenge. As a gas, hydrogen
has a very low energy density.
• This leads to a large tank size even with high pressure storage and short vehicle range.
• Storing hydrogen in liquid form is also problematic as it liquifies at --235°C Storage of
hydrogen may be achieved by solid state hydride storage materials, liquid hydrides,
microglass sphere storage, storage in carbon, storage in zeolites, and similar such
storage.

The properties of hydrogen, natural gas (methane) and gasoline

Boosting by fitting a turbocharger or
supercharger
Direct injection of the hydrogen into the
cylinder (also known as internal mixture
formation)
Mixing cryogenic hydrogen gas with
aspirated air

The properties that contribute to its use as a
combustible fuel are its:
• wide range of flammability
• low ignition energy
• small quenching distance
• high autoignition temperature
• high flame speed at stoichiometric ratios
• high diffusivity
• very low density

• Vegetable oils have better ignition qualities for diesel engines than light alcohols, their
Cetane number being over 30. There are many vegetable oils which can be used in
diesel engines like peanut oil, linseed oil, rapeseed oil.
• The viscosity of vegetable oils is much higher than that of diesel. It can cause problems
in fuel handling, pumping, atomization and fuel jet penetration. This would require
modifications in the engine fuel system.
• Vegetable oils are slower burning. It can give rise to exhaust smoke, fuel impingement on
cylinder walls and lubricating oil contamination. To overcome this combustion system
must be modified to speed up air-fuel mixing. The indirect injection (IDI) engines are
more suitable than direct injection (DI) engines for vegetable oils because of a single
relative large size nozzle hole.
VEGETABLE OIL

• Vegetable oil is an alternative fuel for diesel engines and for heating oil burners. For
engines designed to burn diesel fuel, the viscosity of vegetable oil must be lowered to
allow for proper atomization of the fuel; otherwise incomplete combustion and carbon
build up will ultimately damage the engine.
• Diesel Engine can run on straight vegetable oil as long as the engine is started on diesel
fuel
• A heater is also necessary to keep the vegetable oil warmed to a certain temperature
• Either used cooking oil (from a fryer) or new cooking oil can be used
• A new vegetable oil tank must be installed, and modifications on the heating hoses of the
diesel engine must be done
• The vehicle is started and stopped on diesel fuel, then swtiched over to run off the hot,
straight vegetable oil
• When the engine is running the engine coolant is used to heat the vegetable oil so it has
a similar viscosity that of diesel
VEGETABLE OIL

Benefits of vegetable oil run vehicles:
• CO2 neutral
• Economical, cheaper than diesel
• Excellent system-energy efficiency (from raw "crude" to refined product)
• Sulphur-free
• Protects crude oil resources
• 100% biodegradable
• Non-hazardous for ground, water, and air in case of a spill
• Low fire hazard (flashpoint > 220°C)
• Practical to refuel at home
• Easy to store, more ecological than bio-diesel
• A chance for the farming community and agriculture
VEGETABLE OIL

The term Bio fuel is used to describe the liquid, solid and
gas fuels produced from Biomass to be used in
transportation, heating or energy production.
Types of Bio fuels
• Vegetable oil
• Biodiesel
• Bio alcohols
• Biogas
• Solid Bio fuels
BIO FUEL

Bio diesel is a renewable fuel produced from vegetable oil or
animal fat. Biodiesel contains no petroleum, but it can be
blended at any level with petroleum diesel to create a
biodiesel blend. It can be used in compression-ignition
(diesel) engines with little or no modifications.
 It is a clean burning alternative fuel.
 Bio diesel contains no petroleum, but it can be blended at
any level with petroleum diesel to create a bio diesel blend
It is derived from
 Soy bean Oil Kanuga Oil
 Jatropha Oil
 Corn Oil
 Sunflower Oil
 Cotton seed Oil
 Rice bran Oil
 Rubber seed Oil
BIO DEIESEL

 Renewable source.
 Energy security.
 Availability for all countries.
 Absence of harmful burning emissions. (Reduces serious air
pollutants such as CO, CO2 etc.)
 Safe: Non toxic, Non hazardous, non flammable
 Eco friendly
 Clean burning
 High lubricity
 Fuel efficiency
 Low Greenhouse gases
 Reduces need to import oil
Why Bio- Diesel ?

Bio Diesel found in India
• Jatropha Oil
• Cotton seed Oil
• Kanuga Oil

 Kanuga is a non edible oil
 Kanuga can grow on marginal land, waste land not
suitable for
farming purpose
 Not browsed by animals
 Don’t compete with food crops for land & water sources
 Range varies from 9-90 kg per tree from 7 years old
plant
 1-3 tons of bio diesel/ Ha/ year
 Short gestation 3y & 7y, Long productive life 50 y & 100
y
 Can grow wide variety of environments
 Adaptability to varied agro climatic conditions and soil
types
KANUGA

 Manufactured from vegetable oils, animal fats, or recycled restaurant
greases; reacted with alcohol to produce fatty acid alkyl ester.
 Nontoxic, biodegradable, and reduces serious air pollutants.
 B20 (20% biodiesel, 80% petroleum diesel) can generally be used in
unmodified diesel engines.
 Can be used in pure form (B100), but may require engine modifications.
 Has a higher Cetane number and provides more lubricity.
 B20 contains 9% less energy content per gallon than #2 diesel.

In some respects the properties of vegetable oils are very close to those
of diesel oil but in other they are quite different
 The densities of the vegetable oils are slightly higher compared to
diesel
 the calorific value is slightly lower on mass basis
 Viscosities at room temperature are much higher compared to
diesel oil
 The Cetane number is slightly lower than the diesel oil
 The flash point is very high
 Volatility is quite low
 Carbon residue is very high

 Property comparisons indicate vegetable oil viscosities to
be much higher and eating values to be some what lower
for these oils than for diesel fuels. The difficulties in using
vegetables oils directly in diesel engines can be overcome
by modifying these oils.
 The modifying methods are
1. Heating the oil
2. Thermal cracking of the oil
3. Transesterification

 B20 can generally be used in all unmodified diesel
engines.
 Using biodiesel maintains the same payload capacity
and range and provides similar horsepower, torque,
and fuel economy.

» Potential issues with cold starting. Also, cold weather
storage requires additional steps to keep biodiesel
usable.
» Fuel related failures may not be covered by some OEM
warranties if greater than B5 is used.
» Limited production and availability.

Fuel Cell Ford Focus Fuel Cell Mercedes A-Class
» Hydrogen Fuel Cell Vehicles
» Direct Methanol Fuel Cell Vehicles
» High Efficiency Direct Injection Engines for Light- and Heavy-
Duty Vehicles

Honda Insight
Toyota Prius
» Two models currently available
˃ Toyota Prius (48 mpg)
˃ Honda Insight (64 mpg)
» Potential for very low emissions
» Represent a “Spin-Off” of technology developed for EVs
» Good potential for petroleum conservation

Natural Gas as Fuel in IC Engine
• Natural gas is a mixture of several different gases. The primary constituent is
methane, which typically makes up 85-99 % of the total volume.
• The other constituents include other hydrocarbons, inert gases such as nitrogen,
helium and carbon dioxide, and traces of hydrogen sulphide and water.
• The non-methane hydrocarbons present in natural gas consist primarily of ethane. The
remainder is made up mostly of propane and butane, with some traces of C5 and
higher species.
• Natural gas is an excellent fuel for SI engines. As a gas under normal conditions, it
mixes readily with air in any proportion.
• Unlike liquid fuels it does not need to vaporize before burning.
• Thus cold engine starting is easier especially at low temperatures, and cold-start
enrichment is not required.
• Cold-start enrichment is a major source of CO emissions and emissions-related
problems in gasoline-fuelled SI engines.
• Natural gas has a high ignition temperature, and is resistant to self-ignition. It has
excellent antiknock properties.

INTRODUCTION
 Natural gas (NG) is a mixture of gases (fossil fuel)
 Natural gas is truly a “gas”
 It is colourless, shapeless, and odourless in its pure form
 Deposits found 1 to 2 miles below the earth’s surface
 Natural gas is a fossil fuel comprised mostly of 87% methane, and
is one of the cleanest burning alternative fuels.
 It can be used in the form of:
 Compressed natural gas (CNG)
 Liquefied natural gas (LNG)

Natural Gas as Fuel in IC Engine
• Pure methane has an equivalent research octane number (RON) of 130, the highest of
any commonly used fuel.
• Because of its antiknock properties, natural gas can safely be used with engine
compression ratios as high as 15:1 (compared to 8-10:1 for 91 octane gasoline).
• Natural gas engines using these higher compression ratios can reach significantly
higher efficiencies than are possible with gasoline.

INTRODUCTION
Typical Composition of Natural Gas
Methane CH4 70-90%
Ethane C2H6
0-20%
Propane C3H8
Butane C4H10
Carbon Dioxide CO2 0-8%
Oxygen O2 0-0.2%
Nitrogen N2 0-5%
Hydrogen
sulphide
H2S 0-5%
Rare gases A, He, Ne, Xe trace

COMPRESSED NATURAL
GAS
Light-Duty Vehicle Emissions: CNG vs. Gasoline
• Reduces carbon monoxide emissions 90%-97%
• Reduces carbon dioxide emissions 25%
• Reduces nitrogen oxide emissions 35%-60%
• Potentially reduces non-methane hydrocarbon emissions 50%-75%
• Emits fewer toxic and carcinogenic pollutants
• Emits little or no particulate matter
• Eliminates evaporative emissions

Advantages
 Natural gas is better for, and friendlier to our environment
 Natural gas burns very hot
 Natural gas is easier and safer to store
 Natural gas is very reliable
 Natural gas is a cost-effective fuel
 There is an abundance of Natural Gas
 Economic benefits of natural gas

Disadvantages
 It's a non-renewable energy resource
 Natural gas is colorless, odorless and tasteless
 Carbon Monoxide Poisoning
 Natural gas is a highly flammable substance
 Air Pollution
 Greenhouse gases
 Water Pollution
 Hydraulic fracturing

» CNG used in light- and medium-duty vehicles.
» LNG used in heavy-duty trucks and all natural gas fueled
locomotives.
» CNG stored onboard at 3000 - 3600 psig.
» LNG stored at 50 psig and fuel temperature at -2200
F.

» Recovered from underground reserves.
» Used in two forms: CNG (compressed natural gas) and LNG
(liquefied natural gas).
» CNG and LNG vehicles can demonstrate reduced ozone-forming
emissions compared to gasoline. May have increased
hydrocarbon emissions.
» Contains 59% - 69% less energy content per gallon at 3000 -
3600 psig than gasoline.
» Widespread distribution infrastructure (737 CNG and 32 LNG
refueling stations in operation in 2006).

CNG
 A natural gas under pressure (3600 psi/248bar) which remains
clear and non-corrosive.
 It is odorless so NG companies add “smell” so that it can be
detected.
 It’s octane rating is 130.

WORLDWIDE CNG
 Pakistan currently has the highest number of vehicles running
on CNG in the world and also has the highest number of CNG
stations in the world numbering more than 3600.
 Worlds biggest CNG refueling station is in Singapore (46
pumps).
 Worldwide there are approximately 12.4 million nature gas
vehicles by 2010.

APPLICATION
 Worldwide there are approximately 12.4 million nature gas
vehicles by 2010.
 CNG can used in both petrol and diesel vehicle by CNG kits.
 The Napa Valley Wine Train successfully retrofit a diesel
locomotive to run on CNG before 2002.

ADVANTAGES OF CNG
OVER PETROL & DIESEL
 CNG is cheaper than Petrol and Diesel.
 CNG powered vehicle has,
1.Lower maintenance cost.
2. No evaporation losses.
3.Increase life of lubricating oil.
 Lighter than air.
 Doesn’t leak into ground water.
 High ignition temperature(540oC).
 Produce less pollutant elements.

» CNG refueling stations are either slow-fill (several hours to fill)
or fast-fill (2 - 5 minutes).
» Additional safety modification for maintenance facilities required
by NEC (National Electrical Code) and NFPA (National Fire
Protection Association).
» Higher vehicle costs because of required tank
configuration.
» Shorter vehicle range for CNG vehicles.
» Availability of refueling stations.

DRAWBACKS OF CNG
OVER PETROL & DIESEL
 CNG vehicle needs more space for fuel storage.
 According to conference in IIT Mumbai CNG has one
Radio Active element, which is very harmful for health
and may cause of lung cancer.
So CNG is dangerous than Diesel and Petrol for health.

 Bio-diesel and Solar power best alternatives.
 High quality Bio-diesel is produced from Jatropha and Caster
seeds, which we get at low cost and also the farming of
Jatropha trees in desert is easy.
 Solar energy is the unlimited source of the energy.

» By-product of natural gas processing and crude oil refining.
» HD5, the automotive propane standard, a mixture of 90%
propane and other hydrocarbons.
» Contains 33% - 41% less energy content per gallon than
gasoline.
» LPG vehicles can demonstrate a 60% reduction in ozone-forming
emissions compared to gasoline.
» High octane properties (~104) allow LPG vehicles to operate with
higher compression ratios; leads to higher efficiency/fuel
economy.

» Used in light- and medium-duty vehicles, heavy-duty trucks and
buses.
» Popular choice for non-road vehicles such as forklifts and
agricultural and construction vehicles.
» Many propane vehicles are converted gasoline vehicles.
(Conversion kits include regulator/vaporizer, air/fuel mixer,
oxygen-monitoring closed-loop feedback system, and special
fuel tank.)

» Does not occur to any significant extent on earth in its free,
elemental form.
» Found in chemical compositions such as water and
hydrocarbons, and dry coal.
» Pure hydrogen contains no carbon thus burns to form water with
no CO2 or CO emissions.
» One kg of hydrogen contains roughly equivalent energy to one
gallon of gasoline.
» Can be stored as compressed hydrogen at 5,000 – 10,000 psi or
liquid hydrogen (cooled to -4230
F).

» Emerging fuel for transportation fuel cells.
» Used in modified internal combustion engines.
» Fuel cells use a direct electrochemical reaction to produce
electricity on board the vehicle. This electricity is used to power
electric motors.
» Ongoing demonstration projects in select U.S. areas.

LPG as Fuel in IC Engine
• Liquified Petroleum Gas (LPG) is a product of petroleum gases, principally propane
(C3H8), propylene (C3H6) and butane (C4H10).
• These gases can be liquified at normal temperatures by subjecting them to a moderate
pressure. Owing to the demand from industry for butane derivatives, LPG sold as a fuel
is made up largely of propane.
• Liquified petroleum gases are used as fuels for stoves, trucks, buses and tractors in
many parts of the world.
• The LPG has higher heating value compared to gasoline. Since propane and butane are
heavier than air, the escaping gas will tend to settle and collect in pockets thus creating
an explosion hazard.
• The LPG is suitable for IC engines because of its availability and low carbon content,
thus resulting in drastic reduction in exhaust emissions.
• The LPG has a high self-ignition temperature and a high octane number, which makes it
more suitable for SI engines.

LPG as Fuel in IC Engine
• Engines with natural gas and LPG can run lean because of their better distribution and
higher misfire limits.
• Also, their higher octane numbers, allow an increase in the compression ratio in SI
engines, which consequently improves the thermal efficiency and reduces the exhaust
emissions.

• There are various problems associated with vegetable oils being used as fuel in
compression ignition (C.I.) engines, mainly caused by their high viscosity.
• The high viscosity is due to the large molecular mass and chemical structure of vegetable
oils which in turn leads to problems in pumping, combustion and atomization in the
injector systems of a diesel engine.
• Due to the high viscosity, in long term operation, vegetable oils normally introduce the
development of gumming, the formation of injector deposits, ring sticking, as well as
incompatibility with conventional lubricating oils .
• Therefore, a reduction in viscosity is of prime importance to make vegetable oils a
suitable alternative fuel for diesel engines.
• The problem of high viscosity of vegetable oils has been approached in several ways,
such as preheating the oils, blending or dilution with other fuels, transesterification and
thermal cracking / pyrolysis.
Use of jatropha curcas oil and diesel fuel blends in CI Engine

• Jatropha curcas is a large shrub or tree native to the American tropics but commonly
found and utilized throughout most of the tropical and subtropical regions of the world.
• Several properties of the plant, including its hardness, rapid growth, easy propagation
and wide ranging usefulness have resulted in its spread far beyond its original
distribution.
• The jatropha oil is a slow-drying oil which is odourless and colourless when fresh but
becomes yellow on standing. The oil content of jatropha seed ranges from 30 to 50% by
weight and the kernel itself ranges from 45 to 60%.
• The oil compares well against other vegetable oils and more importantly to diesel itself
in terms of its fuel rating per kilogram or hectare of oil produced. But the greatest
difference between jatropha oil and diesel oil is viscosity.
• The high viscosity of curcas oil may contribute to the formation of carbon deposits in the
engines, incomplete fuel combustion and results in reducing the life of an engine.

The heating value of the vegetable oil is comparable to the diesel oil and the
cetane no. is slightly lower than the diesel fuel.
However, the kinematic viscosity and the ﬂash point of jatropha curcas oil are
several times higher than the diesel oil.
Fuel properties

• Dilution or blending of vegetable oil with other fuels like alcohol or diesel fuel would
bring the viscosity close to a specification range.
• Jatropha oil is blended with diesel oil in varying pro portions with the intention of
reducing its viscosity close to that of the diesel fuel.
• The important physical and chemical properties of the biodiesel thus prepared are given
in Table below. The various blends were stable under normal conditions.

Effect of dilution on viscosity of vegetable oil and biodiesel
• The high viscosity of jatropha curcas oil has been decreased drastically by
partial substitution of diesel oil.
• The viscosity of the vegetable oil was decreased on increasing the diesel
content in the blend.
• Though a substantial decrease in viscosity and density was observed with
70:30 jatropha/diesel (J/D) and 60:40 J/D blends, still the viscosity and density
are quite a lot higher than that of diesel.
• A reduction of viscosity of 55.56% and 62.13% was obtained with 70:30 and
60:40 J/D blends, respectively.
• The corresponding viscosity and the density were found to be 23.447 and
19.222 cSt, and 0.900 and 0.890 g/cc at 30 °C.

• The viscosity and density of jatropha curcas oil were reduced from 52.76 and
0.93292 to 17.481 cSt and 0.880 g/cc, respectively, with 50:50 J/D blend.
• A reduction of viscosity of 66.86% was achieved.
• The viscosity of the 40:60 J/D blend was slightly higher than diesel oil.
• In this case the viscosity was found to be 13.958 cSt and the percentage
reduction of viscosity was 73.55 whereas the viscosity anddensity of blends
comprising 30:70 and 20:80 J/D are close to those of diesel oil.

• Viscosity of 9.848 and 6.931 cSt and density of 0.862 and 0.853 g/cc were
observed with 30:70 and 20:80 J/D, respectively. The corresponding
viscosity reductions were 81 and 86.86%.
• Therefore, 70–80% of diesel may be added to jatropha oil to bring the
viscosity close to diesel fuel and thus blends containing 20–30% of jatropha
oil can be used as engine fuel without preheating.

Effect of temperature on viscosity of jatropha curcas oil and various blends
• From the properties of the blends shown in Table, it has been observed that
biodiesel containing more than 30% jatropha oil have high viscosity
compared to diesel.
• The viscosity of these blends needed to be reduced more in order to make it
suitable as biodiesel to be used in the diesel engine.
• From the literature, it wasfound that heating the fuel makes its spray
characteristics more like those of diesel oil, which is the direct result of
viscosity reduction.
• Therefore, efforts have been made to decrease the viscosity by heating the
biodiesels.
• For this, the viscosities of the oils as well as the blends were measured at
varying temperature in the range 25–75 °C.

Effect of temperature on viscosity of jatropha curcas oil and various blends

• The results show that the viscosity of jatropha oil is higher than diesel oil at
any temperature. However, the viscosity of vegetable oil was decreased
remarkably with increasing temperature and it becomes close to diesel oil at
temperatures above 75 °C.
• Biodiesel containing 70 and 60% vegetable oil has viscosity close to diesel oil
between 70 and 75 °C, and between 60 and 65 °C, respectively.
• Viscosity values of 50:50 J/D and 40:60 J/D are close to diesel in the range of
55–60 °C and at about 45 °C, respectively, whereas the blend containing
30:70 J/D has viscosity close to diesel at the range of 35–40 °C.
• Therefore, the blends of 30:70 and 40:70 J/D may be used with slight heating
or even without heating, particularly in summer season.

Engine test - Effect of brake horse power on specific fuel consumption

• It was observed that the specific fuel consumptions of the oil as well as the blends were
decreased with increasing load from 0.77 to 3.078 and tended to increase with further
increase in BKW.
• The fuel consumptions were also found to increase with a higher proportion of jatropha
curcas oil in the blend.
• Though the blends as well as the jatropha curcas oil maintained a similar trend to that of
diesel, the SFC in the case of the blends were higher compared to diesel oil in the entire
load range.
• This is mainly due to the combined effects of the relative fuel density, viscosity and
heating value of the blends.
• However, blends containing 30:70 and 40:60 J/D have SFC very close to that of diesel oil.
• The SFC values were found to be 0.338 and 0.365 at 3.078 BKW; the corresponding
value for diesel is 0.316.

• The specific fuel consumption of 0.693 was observed using 50:50 J/D blend as fuel
which is comparable to the SFC obtained with diesel oil under the same load.
• The higher density of blends containing a higher percentage of jatropha curcas oil has
led to more discharge of fuel for the same displacement of the plunger in the fuel
injection pump, thereby increasing the SFC.

Engine Test: Effect of BKW on brake thermal efficiency
• Initially with increasing BKW the brake thermal efficiencies of the vegetable oil, diesel
and the blends were increased and the maximum thermal efficiencies were obtained at
BKW of 3.078 and then tended to decrease with further increase in BKW.
• There was a considerable increase in efficiencies with the blends compared to the
efficiency of jatropha oil alone, but the brake thermal efficiencies of the blends and the
jatropha curcas oil were lower than that with diesel fuel throughout the entire range.
• The maximum values of thermal efficiencies with 60:30 and 70:30 J/D were observed
as 21.45% and 20.53%, respectively.

• Among the blends tested, in the case of 30:70 J/D, the thermal efficiency and
maximum power output were close to the diesel values, followed by the 40:60 J/D
blend.
• Corresponding maximum brake thermal efficiencies of 26.09 and 24.36% were
observed with these blends. A reasonably good thermal efficiency of 22.44% was
also observed with the 50:50 J/D blend.
• The maximum thermal efficiency of 27.11% was achieved with diesel, whereas only
18.52% thermal efficiency was observed using jatropha curcas oil.
• The drop in thermal efficiency with increase in proportion of vegetable oil must be
attributed to the poor combustion characteristics of the vegetable oils due to their
high viscosity and poor volatili ty.

Engine Test: Effect of BKW on exhaust gas temperature
• The exhaust gas temperature increased with increase in BKW in all cases. The
highest value of exhaust gas temperature of 554 °C was observed with the jatropha
oil, whereas the corresponding value with diesel was found to be 425 °C only.
• This is due to the poor combustion characteristics of the jatropha curcas oil because of
its high viscosity. The combustion characteristics of the blends were improved by
increasing the proportion of diesel fuel in the J/D blend.
• The exhaust gas temperature for 20:80 J/D was observed to be very close to diesel oil
and the temperatures were comparable to those with diesel oil blends with 30:70 and
40:60 J/D over the entire load.
• The maximum exhaust temperature was recorded as 550 and 540 °C with 70:30 and
60:40 J/D blends, respectively at 3.74 BKW. With 50:50 J/D, the value was found to be
535°C.

Engine Test: Effect of BKW on exhaust gas temperature

• Significant reduction in viscosity was achieved by dilution of vegetable oil with diesel in
varying proportions.
• Among the various blends, the blends containing up to 30% (v/v) jatropha oil have
viscosity values close to that of diesel fuel.
• The blend containing 40% (v/v) vegetable oil has a viscosity slightly higher than that of
diesel. The viscosity was further reduced by heating the blends.
• The viscosity of the blends containing 70 and 60% vegetable oil became close to that of
diesel in the temperature ranges of 70–75 and 60–65 °C, respectively.
• The corresponding temperatures were found to be 55–60 and 45 °C for 50 and 40%
blends, whereas only at 35–40 °C did the viscosity of the 30:70 J/D blend become close
to the specification range.
• Acceptable brake thermal efficiencies and SFCs were achieved with the blends
containing up to 50% jatropha oil.

IC Engine Unit 4 ALTERNATE FUELS.ppt

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