01.Lecture_01_Study of FUEL, Use with worked out problems.ppt

Fundamentals of
Mechanical Engineering
ME-263

Course Details
 Contact Hour: 3.00, Credit Hour: 3.00
 Total weeks: 14, 42 Classes
 Marks Distribution:
Class Test = 60 marks (20%)
Mid Term = 45 (15%)
CP = 15 (5%)
Final Exam = 180 (60%)
Total marks = 300 (100%)

Course Contents
 Part 1 (21 classes):
 Fuels
 Introduction to IC
engines: SI Engine & CI
Engine
 Thermodynamics
 Refrigeration system &
applications
 Study of psychometry
 Air Conditioning systems
& applications
 Part 2 (21 classes):
 Fluid machinery
 Steam Generating Units
with Accessories and
Mountings(Boiler)
 Impulses & Reaction
turbines
 Centrifugal and axial flow
machines
 Pump, Fan , Compressor,
Blower

Fuels
 Fuel is any material that stores Energy that
can later be extracted to perform mechanical
work in a controlled manner.
 Most Fuels produce Energy by various other
exothermic chemical reactions and nuclear
reactions.
 Most common household fuels contain the
element Carbon.
 Fuels that contain carbon and hydrogen only are
called Hydrocarbons. Few traces of sulphur
are also present in it.

Types of Fuel
 There are mainly two types of fuel,
1. Chemical Fuel.
2. Nuclear Fuel.
Chemical Fuel: Chemical fuels are substances that
release energy by reacting with substances
around them, most notably by the process of
oxidation or burning.
A good fuel releases it’s energy over a longer
period of time.
Another word for burning is Combustion ie. we
combine the element with Oxygen gas.

Chemical Fuel
Chemical Fuels can be of two types,
1. Biofuels: Biofuel can be broadly defined as
solid, liquid, or gas fuel consisting of, or
derived from biomass. Biomass can also be
used directly for heating or power— known
as biomass fuel. Biofuel can be produced
from any carbon source that can be
replenished rapidly e.g. plants. Many different
plants and plant-derived materials are used
for biofuel manufacture.
Example: Bio alcohol, biodiesel, wood etc.

Chemical fuel
2. Fossil Fuels: Fossil Fuels are formed from Living
things millions of years ago. They are Hydrocarbons
and are Finite Fuels ie. They will run out in the
future and cannot be regenerated. There are three
main Fossil Fuels:
Coal, Oil and Gas
Oil: This was
formed by dead
sea creatures
falling to the sea-
bed where they
were subjected to
chemical change
by Bacteria.
Coal: This was
formed by the
decay of
Vegetation which
was subjected to
heat and pressure
over a very long
period of time.
Gas was formed
in much the
same way as Oil.
It is often
collected when
drilling for Oil.

Classification of Fuel
 Fuels may be classified into the following
general terms:
1. Solid Fuel
2. Liquid Fuels
3. Gaseous Fuel
Each of these fuels may be subdivided into
the following categories-
1. Natural Fuels
2. Prepared Fuels

Solid Fuel(Natural)
 Wood: At one time it was an extensively used fuel. It
consists of mainly carbon and hydrogen. The average
calorific value of wood is 19700 kJ/kg.
 Peat: It is a spongy humid substance and contains
about 30% water. It has to be dried before use. It is
the first stage in the formation of coal. The average
calorific value of peat is 23000 kJ/kg.
 Lignite or brown coal: It is the next stage of peat in
the coal formation and an intermediate variety
between bituminous coal and peat. It contains nearly
40% moisture and 60% of carbon. The average
calorific value of lignite is 25000 kJ/kg.

Solid Fuel
 Bituminous Coal: It represents the next stage
of lignite in the coal formation and contains
very little moisture(4-6%) and 75 to 90% of
carbon. The average calorific value of
bituminous coal is 33500 kJ/kg.
 Anthracite Coal: It represents the final stage
of coal formation and contains 90% or more
carbon. The average calorific value of
anthracite coal is 36000 kJ/kg.

Solid Fuel(Prepared)
 Wood Charcoal: It is made by heating wood with a
limited supply of air to a temperature not less than
280˚C. It is a good prepared solid fuel and used for
various metallurgical processes.
 Coke: It is produced when coal is strongly heated
continuously for 42 to 48 hours in the absence of air
in closed vessel. This process is known as
carbonisation of coal. It is black color, porous and
smokeless and has a high carbon content (85 to
90%) and higher calorific value than coal.
 Pulverized Coal: The low grade coal with high ash
content is powdered to produce pulverized coal.

Liquid Fuels
 The following liquid fuels are important from the subjects
point of view.
1. Petrol or gasoline: It is the lightest and most volatile
liquid fuel, mainly used for light petrol engines. It is
distilled at a temperature from 65˚-220˚C.
2. Kerosene or Paraffin oil: It is the heavier and less
volatile fuel than the petrol, and is used as heating and
lighting fuel. It is distilled from 220˚-345˚C.
3. Heavy Fuel oil: The liquid fuels distilled after petrol and
kerosene are known as heavy fuel oil. These oils are
used in diesel engines and oil fired boilers. They are
distilled at a temperature from 345˚-470˚C.

Merits and Demerits of Liquid Fuel
over Solid Fuel
Merits
1. Higher Calorific value.
2. Lower storage capacity
required.
3. Better economy in
handling.
4. Better control of
consumption by using
valves.
5. Practically no ashes.
6. Non-deterioration in
storage.
7. Non-corrosion of boiler
plants.
8. Higher efficiency.
1. Higher cost
2. Greater risk of fire.
3. Costly containers
are required for
storage and
transport.
Demerits

Gaseous Fuel
 The natural gas is, usually found in or near the
petroleum fields, under the earth’s surface. It
essentially consists of methane(CH4) together with
small amounts of other gases such as
ethane(C2H6), carbon dioxide(CO2).
 The following gaseous fuels are important from
subject point of view.
1. Coal gas: It is obtained by carbonization of coal
and consists mainly of H2,CO and various
hydrocarbons.
2. Producer Gas: It is obtained by the partial
combustion of coal, coke, anthracite coal or
charcoal in a mixed air-steam blast.

Gaseous Fuel
 Water gas: It is a mixture of H2 and CO and is
made by passing steam over incandescent
coke.
 Mond Gas: It is produced by passing air and a
large amount of steam over waste coal at
about 650C.
 Blast Furnace Gas: It is a by-product in the
production of pig iron in the blast furnace.
 Coke oven gas: It is by-product from coke
oven and is obtained by the carbonization of
bituminous coal.

Merits and Demerits of Gaseous
Fuel:
 Merits:
1. The supply of fuel gas is controllable, hence the
temperature of furnace is easily and accurately
controlled.
2. The high temperature is obtained at a moderate
cost by pre-heating gas and air with heat of
waste gases of combustion.
3. They are directly used in internal combustion
engine.
4. They do not produce ash or smoke.
5. They undergo complete combustion with
minimum air supply.

Merits and Demerits of Gaseous
Fuel
 Demerits:
1. They are readily inflammable.
2. They require large storage capacity.

Natural Gas
WHAT IS IT?
 Principally methane, CH4, with some ethane
(C2H6) and propane (C3H8), and impurities such as
CO2, H2S, and N2.
CALORIFIC VALUE
 Approximately 1,000 Btu/cu.ft (22,500 Btu/lb)

Requirements of Good Fuel
1. A good fuel should have low ignition point.
2. It should have a high calorific value.
3. It should freely burn with a high efficiency,
once it is ignited.
4. It should not produce harmful gases.
5. It should produce least quality of smoke and
gases.
6. It should be economical, easy to store and
convenient for transportation.

Gross or Higher Calorific Value
 The amount of heat obtained by the complete
combustion of 1kg of a fuel, when the products of its
combustion are cooled down to the temperature of the
supplied air, is called gross or higher calorific value of
fuel.
Fuel+O2=CO2+H2O+SO2+heat+flue gas
H2O+heat= Steam
 Dulong’s formula:
HCV=33800 C+144000 H2+9270 S kJ/kg ….(1)
 If the fuel contains oxygen (02), then the formula
becomes as follows:
HCV=33800 C+144000 (H2 – O2/8) + 9270 S
kJ/kg…..(2)

Net or Lower Calorific Value
 When the heat absorbed or carried away by the product
of combustion is not recovered, and the steam formed
during combustion is not condensed, then the amount of
heat obtained per kg of fuel is known as Net or Lower
Calorific Value.
L.C.V.= H.C.V. - heat of steam formed during
combustion.
Let, ms = Mass of steam formed in kg per kg of fuel = 9 H2
L.C.V. = H.C.V. - ms x 2466 KJ/Kg
= H.C.V. - 9H2 x 2466 KJ/Kg

Problem 1
A sample of coal has the following composition by
mass:
Carbon 75%, hydrogen 6%, oxygen 8%, nitrogen
2.5%, Sulphur 1.5% and ash 7%.
Calculate its H.C.V and L.C.V per kg of coal.

Experimental Determination of H.C.V
There are two experimental procedures that are
important from the subject point of view for
determining the H.C.V of fuel.
1.Bomb Calorimeter
2.Boy’s Gas Calorimeter

Bomb Calorimeter
Let, mf =mass of fuel sample burnt in the bomb in kg
mw = mass of water filled in the calorimeter in kg
me = Water equivalent of the apparatus in kg
t1 = Initial temperature of water and apparatus in °C
t2 = Final temperature of water and apparatus in °C
H.C.V= Higher Calorific value
We know that heat liberated by fuel= mf X H.C.V……..(i)
And heat absorbed by water and apparatus
=(mw+ me) cw (t2- t1)………….(ii)

Problem 2
Calculate the H.C.V of a coal specimen from the
following data:
Mass of coal burnt = 1g
Quantity of water in calorimeter = 2.5 kg
Increase in temperature of water = 2.6°C
Water equivalent of apparatus = 390 g
If the fuel contains 6% hydrogen, calculate its H.C.V
and L.C.V.

01.Lecture_01_Study of FUEL, Use with worked out problems.ppt

More Related Content

Similar to 01.Lecture_01_Study of FUEL, Use with worked out problems.ppt (20)

Recently uploaded (20)

01.Lecture_01_Study of FUEL, Use with worked out problems.ppt