Transcript File - Vigyan Pariyojana

Internal Combustion Engines
Faculty - Er. Ashis Saxena
Index
Unit 1
Introduction to I.C Engines
Fuels
Unit 2
SI Engines
Unit 3
CI Engines
Unit 4
Engine Cooling
Lubrication
Supercharging
Testing and Performance
Unit 5
Compressors
Unit - 1
Chapter – 1(b)
Fuels
Fuels
Fuel is any material that is capable of releasing energy when
its chemical or physical structure is changed or converted. Fuel
releases its energy either through chemical means, such as
burning, or nuclear means, such as nuclear fission or nuclear
fusion. An important property of a useful fuel is that its energy
can be stored to be released only when needed, and that the
release is controlled in such a way that the energy can be
harnessed to produce work.
Types of Fuels
Fuels for engines are typically

Gaseous

Liquid

Originally solid also but now very rarely used.
They may also be classified as:

Naturally available or

Artificially derived
Gaseous Fuels
Main fuels for engines are

Natural gas – from nature

Liquefied Petroleum Gas - from refineries

Producer gas - from coal or biomass

Biogas - from biomass

Hydrogen – from many sources
Natural Gas

Found compressed in porous rock and shale formations
sealed in rock strata underground.

Frequently exists near or above oil deposits.

Is a mixture of hydrocarbons and non-hydrocarbons in
gaseous phase or in solution with crude oil.

Raw gas contains mainly methane plus lesser amounts of
ethane, propane, butane and pentane, negligible sulfur and
organic nitrogen.

Some carbon dioxide and nitrogen are present.
Natural Gas: Facts

Existence of natural gas was known to people of ancient Greece, India, and
Persia, in the form of burning springs. These springs were created when
fountains of natural gas, seeping out from cracks in the ground, were ignited
due to lightning.

As per the data for 2006, Russia had the largest deposits of natural gas (27%).
Middle Eastern countries have a total of about 40% of the world's share of
natural gas reserves, with Iran having almost a 14% share.

There are over a million miles of gas pipelines laid, needed to meet the
energy needs of the US alone.

It was used for the first time in the US in 1816, to light street lights in
Baltimore.
Natural Gas: Facts

Over 90% of the gas requirements of the US are fulfilled from deposits found
in the country itself.

It is the third most widely used fuel in the US, after petroleum and coal.

According to the Energy Information Administration, natural gas provides
for 24% of the total energy needs of US.

More than 62% homes in the country rely on natural gas to run stoves, water
heaters, furnaces and other home appliances.

Industries are the largest consumers of natural gas. Besides being used to
produce energy by industries, natural gas is also used as an ingredient in the
manufacture of fertilizers, paints, ink and glue.

It can be used in fuel cells to produce electricity, in place of batteries. This
may increase the efficiency of electricity generation.
Natural Gas: Facts

Although natural gas pipelines and storage facilities have high standards of
safety, companies add a smelly substance to it, so that the leakage of this
colorless, odorless gas can be identified.

The energy content of natural gas is measured in terms of British Thermal Unit
(BTU). One BTU is said to be the amount of heat required to raise the temperature
of one pound of water by one degree Fahrenheit. In the US, however, retail sales
are done in units of Therms. 1 Therm = 1028 BTU.

Despite its various uses one of the major disadvantages of natural gas is that it is
highly combustible, due to which explosions are very likely.

The gas requires sophisticated treatment plants and underground pipelines to be
delivered to the site where it will be used. These installations are expensive and
require high maintenance.
Use of Natural Gas as a fuel
Natural gas may be used as

Liquefied Natural Gas (LNG).

Compressed Natural Gas (CNG).

“Natural” gas when made artificially it is called
substitute, or synthetic or supple-mental natural
gas (SNG).
Natural Gas in Engines

When an engine was switched over to CNG from gasoline, the non-methane
organic gases like CO and NOx, all reduced by 30-60%. Toxic emissions like
benzene, butadiene and aldehydes were much less than with gasoline.

Natural gas can replace diesel fuel in heavy-duty engines with the addition
of a spark ignition system. Engines operate at  = 0.7 giving low in-cylinder
temperatures and hence low NOx.

Heavy-duty natural gas engines are designed to meet low emission vehicle
(LEV) emission standards without a catalytic converter and will meet ULEV
emission standards with a catalytic converter.

For heavy-duty applications, dual fuel operation is attractive, for buses,
locomotives, ships, compressors and generators.
Natural Gas: Advantages

Is more environment friendly than oil or coal. It is largely because
of the fact that it has only one carbon and hence, produces less
emissions. It is a known fact that for the same amount of heat it
emits 30% less carbon dioxide than burning oil, and 45% less carbon
dioxide than burning coal, thereby improving the quality of air.

Is cheap (less expensive than gasoline) and therefore cost-effective.

Can be safely stored and burned.

The process of easily transporting natural gas over land through
pipelines or over water bodies in the form of LNG (Liquid Natural
Gas) is an added pro - it doesn't require high costs.
Natural Gas: Advantages

Most of its natural reserves are still underutilized.

Emits 60-90% less smog-producing pollutants.

Natural gas becomes a primary source of electricity during situations when
demand runs high.

Due to the clean burning process, it doesn't produce ash after energy is
released.

Has a high heating value of 24,000 Btu per pound.

It can provide as long as 24 hours of electricity throughout the week, where
other sources of its kind do not match up to its endurance.

It is widely used as a primary source of heating whilst cooking
Natural Gas: Disadvantages

Because it is a non renewable source of energy, its availability is finite. Critics
also point out that its extraction leaves large craters within the earth.

Is highly volatile (highly flammable), and can be dangerous if handled carelessly.

In gas pipelines, a substance (contains carbon monoxide) that has a strong odor is
added to help detect a leak. But such substances may be harmful and cause
deaths if not carefully handled. In fact, natural gas is the most common cause of
carbon monoxide deaths.

Constructing and managing transportation pipelines costs a lot if not the
transporting of the substance itself.

While it may give off lesser carbon dioxide than other sources of energy, it is
nonetheless damaging the ecosystem.

It isn't used in vehicles as a primary source of fuel since it is a highly combustible
substance.
Natural Gas: Constituents
CNG vs Automotive fuels
CNG vs Automotive fuels
Composition of typical crude oil

Carbon:
80-89%

Hydrogen:
12-14%

Nitrogen:
0.3-1.0%

Sulfur:
0.3-3.0%

Oxygen:
2.0-3.0%

Plus oxygenated compounds like phenols, fatty acids,
ketones and metallic elements like vanadium and
nickel.
Refining of crude oil
Product
Boiling Range, oC
Liquefied Petroleum Gas
40 to 0
Motor Gasoline
40-200
Kerosene, jet fuel (ATF)
170-270
Diesel Fuel
180-340
Furnace Oil
180-340
Lube Oils
340-540
Residual Fuel
340-650
Asphalt
540+
Petroleum Coke
Solid
Refining of crude oil
Qualities of SI engine fuels
Petrol or gasoline is usually used as fuel for spark ignition (SI) engines There are
certain properties that a particular gasoline should have to qualify as SI engine fuel
which are:

Volatility: The gasoline should be volatile; a certain part of it should vaporize at
room temperature to allow easy starting of the engine. Better vaporization of the fuel
facilitates its even distribution inside the cylinders, which in turn leads to better
acceleration of the vehicle.

Dilution of the lubricating oil in crankcase: As the fuel is splashed in the
cylinder, some lubricating oil from the crankcase is also washed away with it. This
leads to overall decrease in the quantity of the lubricating oil and poor lubrication of
the engine's moving parts. To prevent such possibilities, it is important that the type
of gasoline used for the engine should vaporize before it gets combusted.
Qualities of SI engine fuels

Antiknock qualities of the fuel: Abnormal burning or detonation of the fuel
inside the engine leads to the effect known as engine knock. During detonation
large amounts of heat is released inside the engine which excessively increases
the temperature and pressure inside the engine, drastically reducing its thermal
efficiency. The fuel should have the tendency to avoid creating the situation of
detonation; this quality of the fuel is the antiknock property of the fuel.

The antiknock property of the fuel depends greatly on the self-ignition
properties of the fuel, the fuel's chemical composition, and its chemical structure.
The fuel most suitable for the SI engines is the one that has highest antiknock
property, enabling the engine to work with high compression ratios of fuel, which
in turn leads to higher fuel efficiency and higher power production.
Qualities of SI engine fuels

Gum deposits formed from the fuel: When gasoline is stored for longer periods of
time, it has the tendency to oxidize and form gummy, solid substances. When used
with an engine, such gasoline will cause sticky valves and piston rings, carbon
deposits in the engine, gum deposits in the manifold, clogging of carburetor jets,
and enlarging of cylinders and pistons. The gasoline used in the engine should have
a tendency to form lower gum content and have a lower tendency to form gum
during storage.

Low sulfur content: Hydrocarbon fuels may contain sulfur in various forms like
hydrogen sulfide and other compounds. Sulfur is corrosive in nature and it can
cause fuel line corrosion, carburetor parts, injection pumps, etc. Sulfur also
promotes knocking of engine; hence its content in the gasoline fuel should be kept
to a minimum.
Qualities of CI engine fuels
The fuel used in a compression ignition (CI) engine is diesel. Some of the desired
characteristics of CI fuels are:

Knocking characteristics: In case of the CI engine the burning of fuel occurs due
to compression of air. It is desired that as soon as the fuel is injected into the
cylinder, it starts burning, but in practical situations this never happens as there is
always a time lag between the injection of the fuel and burning of the fuel. As the
duration of ignition lag increases, more and more amounts of fuel get accumulated
in the cylinder head. When the fuel is finally burnt, excessively large amounts of
energy is released, which produces extremely high pressure inside the engine. This
causes the knocking sound inside the engine, which can be clearly heard. Thus the
engines should have a short ignition lag so that the energy is produced uniformly
inside the engine and there is no abnormal sound. The ignition of the fuel also
affects starting, warming, and production of exhaust gases in the engine.
Qualities of CI engine fuels

The knocking capacity of the fuel is measured in terms of cetane rating of the fuel.
The fuel you are using for your CI engine should have a cetane number high enough
to avoid knocking of engine.

Volatility of the fuel: Thorough mixing of the fuel and air when fuel is injected in
the cylinder head ensures uniform burning of the fuel. The fuel should be volatile in
nature within the operating temperature range of the cylinder head so that it gets
converted into a gaseous state and mixes thoroughly with compressed air.

Starting characteristics of the fuel: The smooth starting of the vehicle depends
greatly on the fuel used for the vehicle. For easy starting of the vehicle it is
important that the fuel has good volatility so that it mixes with the air uniformly and
it readily forms into the combustible mixture. The high cetane number of the fuel
ensures that the ignition of the fuel will be fast, which in turn will lead to faster
starting of the vehicle.
Qualities of CI engine fuels

Smoke produced by the fuel and its odor: The exhaust gases produced from the
fuel should not have too much smoke and odor.

Viscosity of the fuel: The fuel should have a viscosity low enough so that it can
easily flow through the fuel system and the strainer at the lowest working
temperatures.

Corrosion and wear: The fuel used for the CI engine should not cause corrosion of
any components of the engine before or after combustion.

Easy to handle: Large quantities of fuel for a CI engine have to be transported from
one place to the other, hence it should be easy to handle and transport. The fuel
should have a high flash point and high fire point to avoid it catching fire during
transport.
Rating of engine fuels
 Normally
fuels are rated for their antiknock
qualities.
 The
rating of fuels is done by defining two
parameters
called
Octane
number
(for
Gasoline) and Cetane number (for Diesel).
Rating of SI engine fuels (Gasoline)

Resistance to knocking is an extremely important characteristics of fuel for
SI engines. These fuels differ widely in their ability to resist knock
depending on their chemical composition.

In addition to the chemical characteristics of hydrocarbons in the fuel,
other operating parameters such as fuel air ratio, ignition timing, dilution,
engine speed, shape of combustion chamber, ambient conditions,
compression ratio etc. affect the tendency to knock in engine cylinder
(hence these parameters to be fixed at standard in order to determine
knock resistance characteristics of fuel).

Octane rating reflects the quality, purity, refinement, efficiency and heat
bearing capacity of petrol.
Octane Rating

According to a standard practice, the antiknock value of an SI engine fuel is determined
by comparing its antiknock property with a mixture of two reference fuels, iso-octane
(C8H18) & normal heptane (C7H16).

Iso-octane being a very good antiknock fuel, is arbitrarily assigned a rating of 100 octane
number & normal heptane has very poor antiknock qualities and is given a rating of 0
octane number.

The octane number fuel is defined as the percentage , by volume of iso-octane in a
mixture of iso-octane and normal heptane, which exactly matches the knocking intensity
of the fuel in a standard engine under s set of standard operating conditions.

In the year 2000 we were using leaded fuel which had 0.15 gms of lead per litre. Lead
(added as tetraethyl lead) gives petrol greater antiknock quality (above 100 octane
number), but the presence of lead in petrol meant more emission of CO (carbon
monoxide) which is the reason why the government introduced compulsory use of
unleaded petrol in 2000.
Rating of CI engine fuels (Diesel) – Cetane rating

In CI engines, the knock resistance depends on the chemical characteristics as well
as on the operating and design conditions of the engine.

Therefore, the knock rating of a diesel fuel is found by comparing the fuel under
prescribed conditions of operation in a special engine with primary reference fuels.

The reference fuels are normal cetane, C16H34 which is arbitrarily assigned a cetane
number of 100 and aplha methyl naphthalene, C11H10, with an assigned cetane
number of 0.

Cetane number of a fuel is defined as the percentage by volume of normal cetane in
a mixture of normal cetane and alpha-methyl naphthalene which has the same
ignition characteristics (ignition delay) as the test fuel when combustion is carried
out in a standard engine under specified operating conditions.

Knock resistance property of diesel oil can be improved by adding small quantities
of compounds like amyl nitrate, ethyl nitrate or ether.
Alternate Fuels - Propane

The entire surface transport of India is based on petroleum fuel, but it’s availability is of growing
concern. The production of domestic crude has been declining and the transport system has
been increasingly dependent on imported crude oil to meet its needs. There is a growing
concern that the world may run out of petroleum based fuel resources. All these make it
imperative that the search for alternative fuels is taken in right earnest.

The alternative fuels aspiring to take the place of petroleum are:
Propane

Liquified petroleum gas (LPG) consists mainly of propane, propylene, butane, and butylene in
various mixtures. It is produced as a by-product of natural gas processing and petroleum
refining. With propane’s simple molecular composition, propane - fueled vehicles emit
significantly lower levels of carbon monoxide, hydrocarbons and nitrogen oxides than gasoline fueled vehicles. The level of air - toxic emissions from propane -fueled vehicles is also low.
According to the National Propane Gas Association, U.S.A., spark plugs from a propane vehicle
last from 80,000 to 100,000 miles and propane engines can last two to three times longer than
gasoline or diesel engines.
Alternate Fuels – Alcohol & Hydrogen
Alcohol fuels

Methanol and Ethanol fuel are typically a primary sources of energy; they are convenient fuels
for storing and transporting energy.

These alcohols can be used in "internal combustion engines as alternative fuels", with butanol
also having known advantages, such as being the only alcohol-based motor fuel that can be
transported readily by existing petroleum-product pipeline networks, instead of only by tanker
trucks and railroad cars.
Hydrogen

Hydrogen fuel is an eco-friendly fuel which uses electrochemical cells, or combustion in
internal engines, to power vehicles and electric devices. It is also used in the propulsion of
spacecraft and can potentially be mass produced and commercialized for passenger vehicles
and aircraft.

Hydrogen fuel can provide motive power for cars, boats and airplanes, portable fuel cell
applications or stationary fuel cell applications, which can power an electric motor. Hydrogen
fuel in automotive vehicles is at least as safe as gasoline
Alternate Fuels - Biodiesel
Biodiesel

Biodiesel is made from animal fats or vegetable oils, renewable resources that come
from plants such as, soybean, sunflowers, corn, olive, peanut, palm, coconut,
safflower, canola, sesame, cottonseed, etc.

Once these fats or oils are filtered from their hydrocarbons and then combined with
alcohol like methanol, biodiesel is brought to life from this chemical reaction.

These raw materials can either be mixed with pure diesel to make various
proportions, or used alone.

Despite one’s mixture preference, biodiesel will release a smaller number of its
pollutants (carbon monoxide particulates and hydrocarbons) than conventional
diesel, because biodiesel burns both cleaner and more efficiently. Even with regular
diesel’s reduced quantity of sulfur from the ULSD (ultra-low sulfur diesel) invention,
biodiesel exceeds those levels because it is sulfur-free.
Alternate Fuels - LPG
LPG

Liquefied petroleum gas comes from petroleum refining, and the rest from natural gas
processing.

It consists of hydrocarbons that are vapors, rather than liquids, at normal temperatures and
pressures, but which turn liquid at moderate pressures; In order to liquefy the fuel, it is stored in
sturdy tanks at about 20 times atmospheric pressure.

Its main constituent is propane, and it is sometimes referred to by that name.
Advantages

It's widely available & is cheaper than gasoline (when compared with the price of a gallon of
gasoline with the price of the volume of LPG needed to drive the same distance).

Because LPG enters the engine as a vapor, it doesn't wash oil off cylinder walls or dilute the oil
when the engine is cold, and it also doesn't put carbon particles and sulfuric acid into the oil.
Thus an engine that runs on it can expect a longer service life and reduced maintenance costs.

Its high octane rating (around 105) means that power output and/or fuel efficiency can be
increased, without causing detonation ("knocking").
Alternate Fuels - LPG
LPG Disadvantages

Because its source is partly petroleum, it does less to help relieve the petroleum
dependency problem than some other alternative fuels.

Its somewhat lower energy content compared to gasoline means you need a slightly
bigger tank to get the same driving range;

The tank will also be heavier because it has to be strong enough to withstand the
LPG storage pressure.

Mostly because of the special fuel tank, a vehicle that runs on LPG will typically be
somewhat more expensive than an equivalent gasoline-powered vehicle.

The refueling procedure on an older-style tank involves the release of some raw fuel
vapors (unburned hydrocarbons) into the air.
Alternate Fuels - CNG
CNG

Liquefied natural gas for vehicles comes from the same sources as compressed natural gas
(CNG).
Advantages

Compressed natural gas is like liquefied petroleum gas (LPG) in many ways.

CNG is the least expensive alternative fuel (except electricity) when you compare equal
amounts of fuel energy.

The high octane rating of natural gas allows the CNG-powered vehicles to use a very high
compression ratio and produce more power than stock gasoline versions.

Since the fuel tanks have to withstand such enormous internal pressures, they are incredibly
tough, with good results for safety.

Natural gas is lighter than air and has very narrow flammability limits, if a leak develops the
fuel will dissipate harmlessly into the air without causing a danger of ignition or explosion.

It is a clean fuel.
Alternate Fuels - CNG
CNG Disadvantages

The tanks are quite bulky and heavy, about three times more so than LPG
tanks.

Because of the heavy-duty tanks, there is currently a large price premium
for a CNG vehicle compared to a gasoline version.
Alternate Fuels - LNG
LNG

Liquefied natural gas for vehicles comes from the same sources as compressed natural
gas (CNG).

Unlike liquefied petroleum gas (LPG), which is changed from a vapor to a liquid at room
temperature by application of pressure, LNG has to be cooled to very low temperatures in
order to cause it to liquefy; this makes it hard (though not impossible) to transport via
tanker, and it is usually liquefied at the dispensing station.
Advantages

LNG has all the emissions advantages as CNG.

The liquefaction process amounts to a distillation, so the fuel is essentially pure methane
which prevents variations in fuel quality.

LNG is a somewhat less bulky and heavy way to store natural gas than as CNG in highpressure tanks.
Alternate Fuels - LNG
LNG Disadvantages

Though LNG tanks are less bulky and heavy than CNG tanks, they are still bigger
than tanks for liquid fuels like gasoline, diesel, or alcohols.

They are also more complex and expensive because they have to insulate the fuel
very well in order to prevent it from warming up and boiling off too fast.

Even with modern, rocket-science insulation materials and techniques, a LNG tank
will begin venting fuel if left to sit for several days, so the fuel is best used in highduty-cycle applications like delivery trucks.
Dopes & Additives for fuels
Dopes for SI engine fuels

Gasoline additives or dopes increase gasoline's octane rating or act as corrosion inhibitors or
lubricants, thus allowing the use of higher compression ratios for greater efficiency and power.

Types of additives include oxygenates, antioxidants, corrosion inhibitors, metal deactivators, antiknock
agents, lead scavengers & fuel dyes.
Oxygenates

Oxygenates are usually employed as gasoline additives to reduce carbon monoxide that is created
during the burning of the fuel.

The oxygenates commonly used are either alcohols or ethers:

Alcohols:


Methanol (MeOH)
Ethanol (EtOH)

Isopropyl alcohol (IPA)
Gasoline grade t-butanol (GTBA)
n-butanol (BuOH)
Ethers:

Methyl tert-butyl ether (MTBE)
Tertiary amyl methyl ether (TAME)

Tertiary hexyl methyl ether (THEME) Ethyl tertiary butyl ether (ETBE)

Tertiary amyl ethyl ether (TAEE)
Diisopropyl ether (DIPE)
Dopes for SI engine fuels contd…
Antioxidants

An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. It prevents the
formation of gums that interfere with the operation of internal combustion engines.

The antioxidants commonly used are:

Butylated hydroxytoluene (BHT)
2,4-Dimethyl-6-tert-butylphenol

2,6-Di-tert-butylphenol (2,6-DTBP)
p-Phenylenediamine
Ethylene diamine
Corrosion inhibitor

A corrosion inhibitor is a chemical compound that, when added to a liquid or gas, decreases the
corrosion rate of a material, typically a metal or an alloy.

For fuels, various corrosion inhibitors can be used. Some components include zinc dithiophosphates.

DCI-4A, widely used in commercial and military jet fuels, acts also as a lubricity additive. Can be also
used for gasolines and other distillate fuels.

DCI-6A, for motor gasoline and distillate fuels.

DCI-11, for alcohols and gasolines containing oxygenates.

DCI-28, for very low-pH alcohols and gasolines containing oxygenates.

DCI-30, for gasoline and distillate fuels, excellent for pipeline transfers and storage, caustic-resistant.

DMA-4 (solution of alkylaminophosphate in kerosene), for petroleum distillates.
Dopes for SI engine fuels contd…
Metal deactivators

Metal deactivators, or metal deactivating agents (MDA) are fuel additives and oil additives used to stabilize
fluids by deactivating metal ions.

An example of a metal deactivator used for gasoline and jet fuels is N,N'-disalicylidene-1,2-propanediamine.
Antiknock Agents

Tetra-ethyl lead

Ferrocene
Methylcyclopentadienyl manganese tricarbonyl (MMT)
Iron pentacarbonyl
Toluene
Isooctane
Triptane
Lead scavengers (for leaded gasoline)

A scavenger is a chemical substance added to a mixture in order to remove or inactivate impurities or unwanted
reaction products.

Tricresyl phosphate (TCP)

1,2-Dibromoethane

1,2-Dichloroethane
Fuel dyes

Fuel dyes are dyes added to fuels, as in some countries it is required by law to dye a low-tax fuel to deter its use
in applications intended for higher-taxed ones. Untaxed fuels are referred to as "dyed", while taxed ones are
called "clear" or "white".

Solvent Red 24
Solvent Red 26
Solvent Yellow 124
Solvent Blue 35