ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

ELEMENTS
OF
MECHANICAL ENGINEERING
(BEMEM103)

MODULE -1
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

INTRODUCTION:

Engineering is the practical endeavor in which the tools of mathematics and science are applied
to develop cost-effective solutions to the technological problems facing our society. Engineers
design many of the consumer products that you use every day. They also create a large number
of other products that we do not necessarily see or hear about because they are used in business
and industrial settings.

Nevertheless, they make important contributions to our society, our world, and our planet.
Engineers develop the machinery that is needed to manufacture most products, the factories
that make them, and the quality control systems that guarantee the product‟s safety and
performance. Engineering is all about making useful things that work and impact lives.

INTRODUCTION TO MECHANICAL ENGINEERING:

The discipline of Mechanical Engineering is concerned in part with certain “Elements”

 Design
 Professional practices
 Forces
 Materials
 Fluids
 Energy
 Motion

Mechanical engineers invent machines and structures that exploit those elements in order to
serve a useful purpose and solve a problem. Original design and the practical issue of making
something that works are the themes behind any engineering endeavour.

The engineer might start from a blank sheet of paper, conceive something new, develop and
refine it so that it works reliably, and meanwhile satisfy the constraints of safety, cost, and
manufacturability.
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

ROLE OF MECHANICAL ENGINEERING IN INDUSTRIES AND

SOCIETY:

The field of mechanical engineering encompasses the properties of forces, materials, energy,
fluids, and motion, as well as the application of those elements to devise products that advance
society and improve people‟s lives.

Mechanical engineers research, develop, design, manufacture and test tools, engines, machines,
and other mechanical devices. They work on power-producing machines such as electricity-
producing generators, internal combustion engines, steam and gas turbines, and jet and rocket
engines. They also develop power consuming machines such as refrigeration and air-
conditioning equipment, robots used in manufacturing, machine tools, materials handling
systems, and industrial production equipment.

Mechanical engineers make hardware that works. An engineer‟s contribution to a company or

another organization ultimately is evaluated based on whether the product functions as it
should. Mechanical engineers design equipment, it is produced by companies, and it is then
sold to the public or to industrial customers. In the process of that business cycle, some aspect
of the customer‟s life is improved, and society as a whole benefits from the technical advances
and additional opportunities that are offered by engineering research and development.

Mechanical engineering isn‟t all about numbers, calculations, computers, gears, and grease. At
its heart, the profession is driven by the desire to advance society through technology. The
American Society of Mechanical Engineers (ASME) surveyed its members to identify the
major accomplishments of mechanical engineers.

1. The automobile

2. The Aerospace program

3. Power generation

4. Agricultural mechanization

5. The Aeronautics

6. Integrated-circuit mass production

7. Air conditioning and refrigeration

 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

8. Computer-aided engineering technology

9. Bioengineering

10. Codes and standards

This top ten list of achievements can help us better understand who mechanical engineers are
and appreciate the contributions they have made to our world.

EMERGING TRENDS AND TECHNOLOGIES IN DIFFERENT SECTORS:

Energy: The energy sector is a category that relate to producing or supplying energy. The
energy sector or industry includes companies involved in the exploration and development of
oil or gas reserves, oil and gas drilling, and refining. The energy industry also includes
integrated power utility companies such as renewable energy and coal. Advent of technology
and raising concern on the use of fossil fuels gives an opportunity to think of the energy
harnessing through renewable resources. Increased efficiency in the solar PV cells, ease in the
manufacturing of complicated shapes of a wind turbine blades through various manufacturing
process, newer innovations in the electric vehicles, newer materials compositions to produce
parts used in devises etc., creating the opportunity to extract the energy at low cost through
renewable sources and avoiding the dependency on fossil fuels.

Manufacturing: Manufacturing is the process of converting the raw material into a finished
product. The technology had taken a great leap in the manufacturing sector. Along with side of
conventional manufacturing methods other manufacturing methods are also being practiced in
the industry. Lean manufacturing, just in time manufacturing (JIT), Flexible manufacturing
system (FMS), Computer Integrated manufacturing (CIM) are already in use. Along with this
additivemanufacturing is getting its importance in the new product development which reduces
the material and time.

Automobile: Indian Automobile market is the 3rd largest automobile market in the world.
The automobile market has seen a considerable change in the advance of technology. Electric
vehicles are the next alternative to the conventional fossil fuelled vehicles. Providing the better
customer ride experience electric vehicles are the future of automobile market. Also, Hybrid
vehicles are already in market uses dual fuel technology like electric and gasoline. Automation
is another aspect in the automobile industry. Use of mechatronics, internet, AI automobile
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

manufacturersare striving for the better user interface and comfort in automobile experience.

Aerospace Industry: Invention of new materials like composites, shape memory alloys
added the strength to weight ratio among the material used in the production of Aerospace
vehicles. Also, use of sophisticated manufacturing techniques in the building of aircrafts make
the cost of the air craft vehicles much economical.

Marine Sector: Marine engineering is the discipline that deals with matters related to the
design, innovation, construction and maintenance of seagoing vessels and navigation
equipment. Marine engineers focus primary on the development and production of internal
systems of boats, ships, or submarines. They are engaged in designing propulsion systems,
auxiliary power machinery and operation equipment. Their technical responsibilities also
include working on-board to maintain these systems.

SOURCES OF ENERGY:
“Energy‟ is a word derived from the Greek word “Energia‟, meaning capacity to do work.
Energy exists in various forms.

 The form of energy that bodies in motion possess is called kinetic energy.

 The energy related to the position of a body is called potential energy.

 The energy contained in a chemical system by virtue of the motion of and forces
between the individual atoms and molecules of the system is called internal energy.
There are different other forms of energy namely, kinetic energy, potential energy,
internal energy, mechanical energy, thermal energy, chemical energy etc. All forms of
energy are inter-convertible by appropriate processes.

Energy exists in the earth or comes from the outer space. The energy existing in the earth is
called capital energy and that which comes from the outer space is called celestial or income
energy. E.g. of capital energy: fossil fuels, nuclear fuels and heat traps. E.g. of celestial or
income energy: Electromagnetic energy, gravitational energy, particle energy and potential
energy of meteorites. The useful celestial energy sources are the electromagnetic energy of the
Sun, called direct solar energy. The gravitational energy of the Moon produces tidal energy.
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

The other sources such as wind energy, hydel energy, geothermal energy, biofuels etc. are
derived from the direct solar energy.

Renewable and non-renewable sources of energy:

The conventional and non-conventional energy sources have been classified as renewable and
non-renewable energy sources, depending on whether these sources are continuously
available or will be exhausted.
The renewable sources of energy are defined as the energy sources which are continuously
produced in nature and are essentially inexhaustible at least in the time frame of human
societies. These energy sources replenish themselves naturally in a relatively short time and
therefore will always be available. E.g. of renewable energy sources: direct solar energy, wind
energy, tidal energy, hydel energy, ocean thermal energy, bio energy, geothermal energy, peat,
fuel wood, fuel cells, solid wastes, hydrogen energy etc. Of the above renewable energy
sources, geothermal energy, peat and fuel wood must be used at a rate less than their renewal
rate in the nature, to allow them to build up again in nature.
The non-renewable energy sources are defined as the energy sources which have been
accumulated over the ages and not quickly replenishable when they are exhausted. E.g. Fossil
fuels (coal, petroleum and petroleum products), nuclear fuels and heat traps.

Advantages of renewable energy sources:

1. The renewable energy sources are non-exhaustible.

2. Renewable energy sources can be matched in scale to the need and also can deliver the
energy required for a specific task.

3. Some of the renewable energy conversion systems can be built on or close to the site where
energy is required.

4. The diversity and technologies of renewable energy conversion systems offer more
flexibility in designing the conversion systems compared to the conventional energy
conversion systems.

5. The local or regional self-sufficiency can be achieved by harnessing locally available

renewable energy, which otherwise would be left unutilized.
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

6. Except biomass energy, all other renewable energy sources offer pollution-free environment
and maintain ecological balance.
Disadvantages of renewable energy sources:

1. Some of the energy sources are intermittently available (i.e. not continuously available). E.g.
solar energy, tidal energy, wind energy etc.

2. There is a limit to the rate at which solar energy is received at the Earth.

3. Renewable energy sources like wind energy, tidal energy etc. are concentrated only in certain
regions.

4. State-of-the-art technology in harnessing the renewable sources is yet to be developed to

meet the present day energy requirements.

5. Application of renewable energy sources in transportation sector is not viable as of today.

 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

Types of Fuels:

The important fuels are as follows-

1) Solid fuels

2) Liquid fuels

3) Gaseous fuels

1) Solid fuels: Coal is the major fuel used for thermal power plants to generate steam. Coal
occurs in nature, which was formed by the decay of vegetable matters buried under the earth
millions of years ago under pressure and heat. This phenomenon of transformation of vegetable
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

matter into coal under earth‟s crust is known as Metamorphism. The type of coal available
under the earth‟s surface depends upon the period of metamorphism and the type of vegetable
matter buried, also the pressure and temperature conditions. The major constituents in coal moisture (5-
40%), volatile matter (combustible & or incombustible substances about 50%) and ash (20-50%). The
chemical substances in the coal are carbon, hydrogen, nitrogen, oxygen and sulphur. In the
metamorphism phenomenon, the vegetable matters undergo the transformation from peat to anthracite
coal, with intermediate forms of lignite and bituminous coal.

2) Liquid fuels: All types of liquid fuels used are derived from crude petroleum and its by-
products. The petroleum or crude oil consists of 80-85% C, 10-15% hydrogen, and varying
percentages of Sulphur, nitrogen, oxygen and compounds of vanadium. The crude oil is refined
by fractional distillation process to obtain fuel oils, for industrial as well as for domestic
purposes. The fractions from light oil to heavy oil are naphtha, gasoline, kerosene, diesel and
finally heavy fuel oil. The heavy fuel oil is used for generation of steam. The use of liquid fuels
in thermal power plants has many advantages over the use of solid fuels.
Some important advantages are as follows:

1. The storage and handling of liquid fuels is much easier than solid and gaseous fuels.

2. Excess air required for the complete combustion of liquid fuels is less, as compared to the
solid fuels.

3. Fire control is easy and hence changes in load can be met easily and quickly.

4. There are no requirements of ash handling and disposal.

5. The system is very clean, and hence the labour required is relatively less compared to the
operation with solid fuels.

3) Gaseous fuels: For the generation of steam in gas fired thermal plants, either natural gas or
manufactured gaseous fuels are used. However, manufactured gases are costlier than the
natural gas. Generally, natural gas is used for power plants as it is available in abundance.
The natural gas is generally obtained from gas wells and petroleum wells. The major
constituent in natural gas is methane, about 60-65%, and also contains small amounts of other
hydrocarbons such as ethane, naphthene and aromatics, carbon dioxide and nitrogen. The
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

natural gas is transported from the source to the place of use through pipes, for distances to
several hundred kilometres. The natural gas is colourless, odourless and non-toxic. Its calorific
value ranges from 25,000 to 50,000 kJ/m3, in accordance with the percentage of methane in
the gas. The artificial gases are producer gas, water gas coke-oven gas; and the Blast furnace
gas. Generally, power plants fired with artificial gases are not found. The gaseous fuels have
advantages similar to those of liquid fuels, except for the storage problems. The major
disadvantage of power plant using natural gas is that it should be setup near the source;
otherwise the transportation losses are too high.

Solar Power Plant:

Solar energy is the energy obtained by capturing heat and light from the Sun. Energy from the
Sun is referred to as solar energy. Technology has provided a number of ways to utilize this
abundant resource. It is considered a green technology because it does not emit greenhouse
gases. Solar energy is abundantly available and has been utilized since long both as electricity
and as a source of heat.
Solar radiation is radiant energy emitted by the sun from a nuclear fusion reaction that creates
electromagnetic energy. The spectrum of solar radiation is close to that of a black body with a
temperature of about 5800 K. About half of the radiation is in the visible short-wave part ofthe
electromagnetic spectrum.
Solar Constant:

This is the amount of energy received in unit time on a unit perpendicular to the suns direction
at the mean distance of the earth from the sun. The surface of the earth receives about 1014 kW
of solar energy from the sun. One square meter of the land exposed to direct sun-light receives
an energy equivalent of about 1 kW of power. The radiant solar energy falling on the earth
surface is directly converted into thermal energy. The surfaces on which the solar rays fall are
called collectors.
There are two types of collectors:

(a) Flat plate collectors

(b) Focusing collectors.

 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

Liquid Flat Plate Collectors:

It has the following components:

(a) Absorbing plate

• Made of Copper, Aluminium or steel.

• It is coated with material to enhance the absorption of solar radiation.

• From the absorbing plates heat is transferred to tubes which carry either water or air.

(b) Transparent covers

• Sheets of solar radiation transmitting materials placed above the absorbing plate.

• They allow solar energy to reach the absorbing plate while reducing convection, conductionand re-radiation
heat losses.
(c) Insulation

• It minimizes and protects the absorbing plate from heat losses.

 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

Working:

Sun‟s rays falling on the transparent covers are transmitted to the absorbing plate. The absorbing plate usually
of Cu, Al or galvanized iron is painted dead black for maximum absorption. The collector (plate) will absorb the
sun energy and transfer it to the fluid in the pipe beneath the collector plate. Use of flat mirrors on the sides
improves the output.

Solar Pond Technology:

A salinity gradient solar pond is an integral collection and storage device of solar energy. By virtue of having
built-in thermal energy storage, it can be used irrespective of time and season. In an ordinary pond or lake, when
the sun's rays heat up the water this heated water, being lighter, rises to the surface and loses its heat to the
atmosphere. The net result is that the pond water remains at nearly atmospheric temperature. The solar pond
technology inhibits this phenomenon by dissolving salt into the bottom layer of this pond, making it too heavy
to rise to the surface, even when hot. The salt concentration increases with depth, thereby forming a salinity
gradient. The sunlight which reaches the bottom of the pond remains entrapped there. The useful thermal energy
is then withdrawn from the solar pond in the form of hot brine. The pre-requisites for establishing solar ponds
are: a large tract of land (it could be barren), a lot of sun shine, and cheaply available salt (such as Sodium
Chloride) or bittern. Generally, there are three main layers. The top layer is cold and has relatively little salt
content. The bottom layer is hot -- up to 100°C (212°F) -- and is very salty. Separating these two layers is the
important gradient zone.
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

Photovoltaic Cell:

Solar energy can be directly converted to electrical energy by means of photovoltaic effect. Photovoltaic effect
is defined as the generation of an electromotive force (EMF) as a result ofthe absorption of ionizing radiation.

Devices which convert sunlight to electricity are known as solar cells or photovoltaic cells. Solar cells are
semiconductors, commonly used are barrier type iron-selenium cells. Iron- selenium cells consist of a metal
electrode on which a layer of selenium is deposited. On the top of this a barrier layer is formed which is coated
with a very thin layer of gold. The layer of gold serves as a translucent electrode through which light can
impinge on the layer below. Under the influence of sunlight, a negative charge will build up on the gold
electrode and a positive charge on the bottom electrode. This difference in charge will produce voltage in
proportion to the suns radiant energy incident on it.
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

THERMAL POWER PLANT

1. Conveyor Belt

The coal from the coal storage area is transported to the plant though a large conveyer belt. The load
carrying capacity of this belt is very high as a very large amount of coal is required every day.
2. Pulverizing Plant

The coal so arrived by the conveyor cannot be used the way it is, it is first converted into powder form
also known as pulverized coal. It is made to rotate in a cylindrical tank at high speed with lots of
spherical steel balls and thus converted into powder. Pulverizing plant also has the storage for un-
pulverized coal and can store upto 30 hours of coal feed.
3. Boiler

The pulverized coal is feed into the boiler through big fans blowing hot air. Boiler has many tubes
filled with water, in these tubes water boils upto 1000 degree Fahrenheit and flames goes as high as 50
meters in the boiler
4. Turbine

High pressure steam from boiler at one thousand degree Fahrenheit and 3500 pounds per square inch
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

of pressure is then feed to the steam turbine which converts its pressure energy into
mechanicalenergy.
5. Generator

Generator uses the mechanical energy so generated by the turbines to generate

electricity atconsiderably high voltage
6. Condenser

steam leaving the turbines is condensed in a condenser, to be pumped back to the

boiler. Cold waterfrom a water source (river) or expansion process is used to cool
down the steam into water.

WORKING

The working of a coal power plant start with the arrival of coal from the coal mines
through trains. This coal is then taken to the pulverizing plant for converting it into
powder form.
The main reason behind converting it into powder is to increase its efficiency of
burning, by increasing its exposed surface area that would come in contact with fire
in burner, compared to solid coal.
This coal dust is then feed to the boiler through a blower fan; thermal energy released
from this fuel is used to boil the water upto 1000 degree Fahrenheit, thus converting
it into a high pressure steamwhich is transferred to the turbines.

Advantages:

 Less initial cost as compared to other generating stations.

 It requires less land as compared to hydro power plant.

 The fuel (i.e. coal) is cheaper.

 The cost of generation is lesser than that of diesel power plants.

Disadvantages:

 It pollutes the atmosphere due to the production of large

amount of smoke.This is one of the causes of global
warming.
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

 The overall efficiency of a thermal power station is low (less than 30%).

SOLAR POWER PLANT:

WORKING OF SOLAR POWER PLANT

As sunlight falls over solar cells, a large number of photons strike the p-type region of silicon.
Electron and hole pair will get separated after absorbing the energy of photon. The electron
travels from p-type region to n-type region due to the action of electric field at p-n junction.
Further the diode is reversed biased to increase this electric field. So this current starts flowing
in the circuit for individual solar cell. We combine the current of all the solar cells of a solar
panel, to get a significant output.

Solar power plant have a large number of solar panels connected to each other to get a large
voltage output. The electrical energy coming from the combined effort of solar panels is stored
in the Lithium ion batteries to be supplied at night time, when there is no sunlight.

Energy Storage:

Storage of the energy generated by the solar panels is a important issue. Sometimes the unused
energy generated during daytime is used to pump water to some height, so that it could be used
to generate electricity using its potential energy when required or mainly at night time.
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

Advantages of Solar Energy:

 Most clean and renewable source of energy.
 It is available in abundance and endless.
 It provides electricity at low cost, as fuel is free.
 With new research in this sector we now have a good power storage solution.
 Keeping in mind the pollution and cost of fossil fuel, it‟s becoming the most reliable
source of clean energy.
Disadvantages of Solar Power Plant:
 It requires a lot of land to be captured forever.
 Initial cost of installation is too high.
 The energy storage options are not efficient and moreover costly if efficient.
 Power production is quite low as compared to nuclear or other resources to produce
power.
 There is a problem if it is cloudy for few days.
Applications:
Solar power plant is powering cities in most efficient manner. Solar panels could be used to
generate electricity individually for each house especially in remote areas.

Wind energy:

Wind energy is the energy contained in the force of the winds blowing across the earth surface.
Wind energy is defined as the kinetic energy associated with the movement of large masses of
air over the earth‟s surface. The circulation of the air in the atmosphere is caused by the non-
uniform heating of the earth‟s surface by the sun. The air immediately above warm area
expands and becomes less dense. It is then forced upwards by a cool denser air which flows in
from the surrounding areas causing wind.
Power in the wind:

Wind possesses kinetic energy by virtue of its motion. Any device capable of slowing down
the mass of moving air, like a sail or propeller, can extract part of this energy and convert into
useful work. The kinetic energy of one cubic meter of air blowing at a velocity V is given by,
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

In one second, a volume element of air moves a distance of V m. The total volume crossing a
plane, one square meter in area and oriented normal to the velocity vector in one second is
therefore V m3.
The rate at which the wind energy is transferred, i.e., wind power is given by,

No device, however well designed can extract all the wind energy because the wind would
have to be brought to halt and this would block the passage of incoming air through the rotor.
It has been found that for maximum power output the exit velocity is equal to one-third of the
entrance velocity. Thus a maximum of 60% of the available energy in the wind is converted
into mechanical energy.

Wind energy conversion:

A windmill is the oldest device built to convert the wind energy into mechanical energy used
for grinding, milling and pumping applications. It consists of a rotor fitted with large sized
blades. Now improvement in performance is achieved by applying sound engineering and
aerodynamic principles. Nowadays the wind energy is used to produce electrical energy. Wind
energy is converted into mechanical energy in wind turbines. These wind turbines are coupled
to generators the mechanical energy is converted into electrical energy.
 ELEMENTS OF MECHANICAL ENGINEERING (BEMEM103)

Hydro Power Plants:

In hydroelectric power plants the potential energy of water due to its high location is converted
into electrical energy. The total power generation capacity of the hydroelectric power plants
depends on the head of water and volume of water flowing towards the water turbine.
The hydroelectric power plant, also called as dam or hydro power plant, is used for generation
of electricity from water on large scale basis. The dam is built across the large river that has
sufficient quantity of water throughout the river. In certain cases where the river is very large,
more than one dam can built across the river at different locations.
Working Principle of Hydroelectric Power plant:

The water turbine changes the kinetic energy of the falling water into mechanical energy at the
turbine shaft. In simple words, falling water spins the water turbine. The turbine drives the
generator coupled with it and converts mechanical energy into electrical energy. This is the
basic “working principle of hydroelectric power plant.”
 Nuclear Power Plant:

The schematic diagram of nuclear power station is shown in figure. A generating station in
which nuclear energy is converted into electrical energy is known as nuclear power station.
The main components of this station are nuclear reactor, heat exchanger or steam generator,
steam or gas turbine, AC generator and exciter, and condenser.

The reactor of a nuclear power plant is similar to the furnace in a steam power plant. The heat
liberated in the reactor due to the nuclear fission of the fuel is taken up by the coolant circulating
in the reactor. A hot coolant leaves the reactor at top and then flows through the tubes of heat
exchanger and transfers its heat to the feed water on its way. The steam produced in the heat
exchanger is passed through the turbine and after the work has done by the expansion of steam
in the turbine, steam leaves the turbine and flows to the condenser. The mechanical or rotating
energy developed by the turbine is transferred to the generator which in turn generates the
electrical energy and supplies to the bus through a step-up transformer, a circuit breaker, and
an isolator. Pumps are provided to maintain the flow of coolant, condensate, and feed water.

TIDAL POWER PLANT

WORKING PRINCIPLE OF TIDAL POWER PLANTS:

Tide or wave is periodic rise and fall of water level of the sea. Tides occur due to the attraction of sea water by
the moon. Tides contain large amount of potential energy which is used for power generation. When the water
is above the mean sea level, it is called flood tide. When the water level is below the mean level it is called
ebb tide.

Working: The arrangement of this system is shown in figure. The ocean tides rise and fall and water
can be stored during the rise period and it can be discharged during fall. A dam is constructed
separating the tidal basin from the sea and a difference in water level is obtained between the basin
and sea.

During high tide period, water flows from the sea into the tidal basin through the water turbine.
The height of tide is above that of tidal basin. Hence the turbine unit operates and generates
power, as it is directly coupled to a generator. During low tide period, water flows from tidal
basin to sea, as the water level in the basin is more than that of the tide in the sea. During this
period also, the flowing water rotates the turbine and generator power.

The generation of power stops only when the sea level and the tidal basin level are equal. For the
generation of power economically using this source of energy requires some minimum tide height
and suitable site. Kislaya power plant of 250 MW capacity in Russia and Rance power plant in
France are the only examples of this type of power plant.
 Advantages of tidal power plants:
1. It is free from pollution as it does not use any fuel.
2. It is superior to hydro-power plant as it is totally independent of rain.
3. It improves the possibility of fish farming in the tidal basins and it can providerecreation to
visitors and holiday makers.
Disadvantages:
Tidal power plants can be developed only if natural sites are available on the sea coast. As the
sites are available on the sea coast are always far away from load centres, the power generated
has to be transmitted to long distances. This increases the transmission cost and transmission
losses.

Introduction to Bio-fuels:

Bio Fuels are liquid fuels which are derived from biomass or bio waste. Bio fuels are produced
from sugar crops, starch crops, oilseed crops and animal fats.
The most common first-generation biofuels are:

Biodiesel: extraction with or without esterification of vegetable oils from seeds of plants like
soybean, oil palm, oilseed rape and sunflower or residues including animal fats derived from
rendering applied as fuel in diesel engines.

Bioethanol: fermentation of simple sugars from sugar crops like sugarcane or from starch
crops like maize and wheat applied as fuel in petrol engines

Bio-oil: thermo-chemical conversion of biomass. A process still in the development phase

Biogas: anaerobic fermentation or organic waste, animal manures, crop residues an energy
crops applied as fuel in engines suitable for compressed natural gas.

Biochemical: modification of the bio-ethanol fermentation process including a pretreatment

procedure

Thermo chemical: modification of the bio-oil process to produce syngas and methanol, Fisher-
Tropsch diesel or dimethyl ether (DME).
Applications:

 Biogas is cheap and sustainable fuel used in lighting, cooking or generating electricity.

 Biodiesel finds its use in automotive industry mainly in cars and trucks.

 Small engines are seen in lawn movers and chain saw.

 The marine industry finds application of biofuel in suitable blend mixtures to be used
in boats and ships.
Problems Associated:
• Biodiesel is compatible with current engines but with certain IssuesBiodiesel exhibits cold
weather problems
• Some types of biodiesel have exhibited storage in stability that could lead to engine problems

• Diesel additives may not provide the same benefits when used with biodiesel.

• Sometimes, vegetable oils create adverse effects on engine components due to their volatility,
molecular structure and high viscosity.
 STEAM FORMATION AND APPLICATIONS

Steam is the gaseous phase of water. It utilizes heat during the process and carries large quantities
of heat later. Hence, it could be used as working substance for heat engine.
Steam exists in various types and conditions namely, wet steam, dry saturated steam (dry steam) &
Superheated steam
a) Wet steam

Wet steam is defined as a two-phase mixture containing saturated liquid and vapour
(steam) formed at the saturation temperature and at a given pressure. The wet steam formed
contains small water particles held in suspension that has not yet absorbed the latent heat and
evaporated
b) Dry saturated steam (Dry steam)

Dry steam is a pure steam that does not contain water particles in suspension. It is defined as
the steam that exists completely in pure vapour form at the saturation temperature and at a given
pressure.
c) Superheated steam(tsup)

It is defined as the steam that is heated beyond its dry saturated state to a temperature higher
thanits saturation temperature and at a given pressure. The temperature at which the superheated
steam is formed is called the superheat temperature

FORMATION OF STEAM

 Steam is formed when water is heated above its boiling temperature. The process
offormation of steam is as follows
 Consider 1 kg. of water at 0°C taken in a cylinder, fitted with a freely moving piston.
Aweight W is placed over the piston as shown in figure (a).
 The weight of the piston and the weight W placed over the piston exerts a
constantpressure P on the water.
Let V be the volume occupied by the water in the cylinder. The condition of water at 0°C is

represented by a point A on the temperature enthalpy (T-H) diagram as shown in figure

(A).Fig A. temperature – enthalpy (T-H) diagram
When water is heated at constant pressure, it is converted to steam. The various stages
involved in this processare discussed below.

1) On heating, the temperature of the water rises and at a certain temperature water begins to
boil(evaporate). The temperature at which water starts boiling is known as saturation
temperature and is denoted by ts. The heating of water from 0°C to the saturation temperature
(ts) is shown by the line AB on T-H diagram. At this temperature, there is a slight increase in
the volume of water(Vf) as shown in figure (b)

2) When water is heated beyond the saturation temperature, evaporation of water takes place.
At this stage, water exists as a two-phase mixture containing saturated liquid and water
vapour occupying volume Vfg, as shown in figure (c). The steam in this condition is called
wet steam. Evaporation of water continues at the same saturation temperature until the whole
of the water is completely converted into steam. This process is shown by the line BC on T-H
diagram.

3). At point C, the steam formed does not contain water vapour (water particles in
suspension) and hence the steam in this state is called thy steam or dry saturated steam. The
volume occupiedby the dry steam is shownin figure (d).

4) If heating is further continued at point C, the temperature of the steam increases above the
saturation temperature and this temperature is called superheat temperature denoted by tsup.
The steam in this condition is called superheated steam.The process of heating the dry steam
is called superheating and is shown by the line CD on T-H diagram. The volume occupied by
the superheated steam is shown in figure (e).
Steam properties:
 Applications of steam:
1. Application of Steam in Sugar Industry:
Steam boilers are very important in the processing operations of crystallization and drying in sugar
mills. Additionally, boilers in sugar industry also generate electricity through cogeneration plants.
Stages of Sugar extraction from Sugarcane:
1. Washing

2. Extraction

3. Purifying juice

4. Crystallization

5. Centrifugation

6. Drying

Crystallization:
Crystallization is a major process stage that relies on a steam boiler. In the crystallization process, a
vacuum pan evaporates the syrup to saturate with sugar crystals through a process, termed seeding.
This seed is pure sucrose suspended in alcohol and glycerine that is added to the syrup. The minute
grains of sugar in the solution helps in extracting the sugar in the solution and forming it into
crystals. With the boiling of the mixture in the vacuum pan, the crystals convert into a paste known
as „massecuite‟ that is a mixture of sugar crystal and syrup. The mixture is further processed in a
large container named „crystallizer‟ to continue crystallization by stirring and cooling the massecuite.
Drying:
Large hot air dryers are used to dry damp sugar crystals and reduce their moisture content to as low
as 0.02% and then pass it through hot air in a granulator. The dried crystals are later segregated as
per their sizes and packed to transfer to the market.
2. Application of Steam in Dairy Industry:
Steam is quite commonly used for heating and sterilizing dairy equipment, both on the farm and in
the dairy manufacturing plant. It is used in the small self-contained oil or electric sterilizers and in
large continuous can washers. Boilers in the dairy industries mainly perform the processes of milk
pasteurization and Ultra Heat Temperature (UHT) to ensure that the milk is safe for consumption
and free from harmful bacteria for optimal shelf life. The milk processing plants utilize steam for
processing and pasteurizing raw milk and dairy products under heat treatment. It leads to the
process and production of various dairy products such as milk powder, yogurt, cheese, condensed
 milk, skimmed milk, butter, ghee, and cream.
3. Application of Steam in Paper Industry:
Steam is pivotal in the paper industry for the process of drying the paper, energy requirement, and
the cooking of wood chips in the digester. Some of the essential requirements of steam in paper
processing are,
Uniform Heating:
The utilization of rolls in paper processing requires it to be heated internally with steam. Therefore,
it is essential to maintain an even temperature across the surface of the rolls for uniformity and
high-quality products. Steam is an ideal choice as it condenses and distributes heat evenly.
Steam Carries Ample Heat:
Most processing plants require a considerable amount of energy, and the paper industry is no
different. One of the optimal ways to carry energy for processing operation is through latent heat in
steam. For instance, 150 psig of saturated steam carries around 3.5 times heat content, and the energy
is released as soon as the steam comes in contact with the internal surface of the roll.
Precision in Steam Temperature:
As temperature demand increases or the higher-grade papers are manufactured, higher pressure and
temperature are needed. The plant operators can control the pressure and set the steam temperature
inside the roll. The saturated steam maintaining the same temperature at a given pressure allows the
operators to control the pressure and steam temperature as required.
4. Application of Steam in Food Processing Industry:
The food industry needs heat at every stage of the process. Direct heat or heat in the from of steam is
an essential factor of food processing industry. Inside the beverage business, steam is used for
cooking, drying, and warming, and for general utilize-cleaning. Steam is also used to eliminate
microbiological risk in food.
Steam used by food processors commonly falls into two broad categories. The first is the so- called
“culinary,” “sanitary” or “clean” steam. This type of steam is used for direct injection into the
product or to clean or sterilize product contact surfaces. We will refer to steam in this category as
“culinary” steam. Any additives in culinary steam must meet all applicable FDA and USDA
requirements for human consumption.
The second category of steam used by food processors is often referred to as “utility steam” or just
simply “steam.” Ordinary plant steam can be used in most applications that do not involve contact
with food products or with surfaces that contact food products. An example of a non- contact use of
plant steam is indirect heating such as radiant heaters (a type of indirect steam heater) used in
 residential and commercial applications.
5. Application of Steam in Power Generation:
Since from centuries, Steam is used to drive the locomotive and also in the production of electrical
energy. A steam/thermal power station uses heat energy generated from burning coal to produce
electrical energy.
Thermal powerplant uses the Rankine cycle. This is the cycle of the steam produced in the boiler,
then taken to the Steam turbine (prime mover). From the turbine the steam is cooled back to water
in the Condenser, the resulting water is fed back into the boiler to repeat the cycle.