By

Prof. Vipul R.Navale

Unit-I

Introduction of Energy Sources &

Its Conversion

SPPU, First Year Engineering

(2023-24)

CONTENT

^1st

^MILESTONE

Introduction to SME

1. Concept of work, Energy and Power
2. Forms of Energy
3. Renewable and Non-renewable Energy Sources
4. Energy conversion Devices

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1. Calculation of hardness of water
2. Chemical analysis of water:
3. Hardness determination
4. Ddetermination of alkalinity in water
5. Effects of using hard water in boiler for steam generation

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^2nd

^MILESTONE

^3rd

^MILESTONE

16. Pumps
17. Compressors
18. Hydraulic Turbines

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UNIT-1

¹⁸

^Topics

5. Thermal (Steam) Power Plant
6. Hydroelectric Power Plant
7. Nuclear Power Plant
8. Solar Power Plant
9. Photovoltaic (PV) cell or Solar Cell
10. Geothermal Power Plant
11. Wind Energy
12. Hydrogen Energy
13. Biomass Energy
14. Tidal energy
15. Grades of Energy

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Systems In Mechanical Engineering

Introduction of Energy

Sources & Its Conversion

Vehicle and their Specifications

Introduction to Thermal Engineering

1. Concept of Work, Energy and Power

• Work

Work is defined as the product of Force applied (F) and Displacement (d) of the object. Work can be obtained by following Formula, when F Newton force acts on the body which displaces body by distance d meter.

W = F × d Nm or Joule

• Example: A force of 30 N is applied on an object, which moves that object 3 meters in the same direction of the force. What is the work done by force?

• Solution: Work done W= 30 N ×3 m = 90 Joule (J)

• One Calorie (Cal)

It represents heat which will rise the temperature of 1 g of water by 1° C at normal atmospheric pressure.

1 Cal = 4.184 Joule

• One joules represents the energy needed to lift an object weighting one Newton (N) to the height of one meter (m) On earth 1N=100g

• Joule

A Joule is a metric unit equal to a Newton meter or the amount of work done when a force of one newton is moved by 1 meter. It measures all forms of energy including heat

Example: 60W light bulb represents 60 Joule light energy per second.

• Energy

Energy is defined as the capacity or ability to do work and

The SI unit of energy is joules (J).

2. Forms of Energy

• Kinetic Energy

It is defined as energy due to the motion of the molecules. It is represented as

KE = 1/ 2 m V2 where m: mass in kg & v: velocity m/s

• Potential Energy

It is defined as the energy stored in an object and is measured by the amount of work done.

PE = m g h where m: mass in kg h: Height in m g: 9.8 m/s2

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• Mechanical energy

It is the sum of Kinetic Energy and Potential Energy. Other Forms of Energies are: Chemical energy, Electrical energy, Magnetic energy, Nuclear energy, Elastic energy, Gravitational energy, Thermal heat energy etc.

Basic Examples on Work & Power

• Example: A 1000 kg truck is lifted by garage hoist to 2 meters above the ground in 15 seconds. Find the power delivered to the truck.

Solution

Force acted F = m×g = 1000 × 9.81 = 9810 N

Work Done W = F × d = 9810 N × 2 m = 19620 Nm = 19620 J

Power Delivered to Truck P = Work done / time = 19620J / 15s

= 1308 J / s = 1308 W

Basic Examples on Work & Power

• Example: If a boy lifts his 40 kg body by distance of 0.25 m in 2 seconds, then what is the power delivered by him?

Solution

Work Done W = F × d= mg × d

= 40 kg × 9.81× 0.25 m

= 98.1 J

Power Delivered by boy P = Work done / time = 98.1 J / 2 s =

P = 49.02 Watt

3.Renewable and Non-renewable Energy Sources

• Renewable Energy

The energy which is available freely in nature and never exhausts is called as Renewable Energy. It is also known as Non-Conventional Energy Sources. These are cleanest sources of energy means that it does not directly produce greenhouse gas emissions or air pollutants.

• Non-Renewable Energy

The energy which is exhaustible and it takes millions of years to form is called as Non-Renewable Energy. It is also known as Conventional Energy Sources. These are natural resources that are available in a limited amount and cannot be remade.

4. Energy conversion Devices

• Electric bulb is energy conversion device which produces light (which is the desired form of output from a bulb), but we also get heat from the bulb (undesired form of energy from an electric bulb).

5. Thermal (Steam) Power Plant

Construction and Working of Thermal (Steam) Power Plant

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• Boiler: It is a closed vessel made up of steel. It converts the water into high pressure, high temperature steam. It contains the furnace inside where the combustion of coal takes place.

Coal is fed to Furnace and Combustion of coal generates a large amount of heat which turns feed water into high pressure high temperature steam.

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• Turbine: It is the mechanical device which converts the kinetic energy of the high-pressure steam to the mechanical energy by rotation of turbine blades

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• Generator: It is connected with the turbine shaft and converts the mechanical energy of the turbine to the electrical energy.

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• Condenser: It condensates (Vapour to liquid) the steam that comes out from the turbine. It converts the low-pressure steam to water. It is connected to the cooling tower.

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• Cooling Tower: It is a tower which contains cold water. Cold water is circulated into the condenser for the cooling of the residual steam from the turbine.

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• Chimney: It is used to release the hot burnt gases or smoke from the furnace to the environment.

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• Feed Water pump: It is used to circulate the feed water to the boiler.

6. Hydroelectric Power Plant

Construction and Working of Hydroelectric Power Plant

• Dam- It is a concrete barrier across the way of the river. The catchment area behind the dam creates a huge water reservoir. The trash rack is provided to filter the water before it flows through the penstock. Water has Potential Energy stored due to head H.

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• Penstock- It is a steel pipeline of suitable diameter connected between Dam and powerhouse. Water flows down from reservoir to powerhouse through the penstock. It gives Kinetic Energy to water. Nozzle increases the velocity of water flow.

• Powerhouse- It consist of water turbines which converts Kinetic Energy of water into Mechanical Energy. This turbine is connected to Generator shaft which converts Mechanical energy into Electrical Energy.

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• Tail race-It is a flow of water discharged from the turbine to the river.

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• Surge tank- It is a protective system, which used to protect the penstock from bursting out due to sudden variation of flow of water.

7.Nuclear Power Plant

Construction & Working of Nuclear Power Plant

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• Nuclear reactor: It is heavily insulated primary Circuit of the plant where nuclear fission of unstable heavy uranium-235 takes place. Moderators (graphite) &control rods (Cadmium, Boron) keeps Nuclear reaction under control.

Moderator reduces the production of neutrons & control rods absorb the neutrons. A large amount of energy liberated in the reactor is transferred to the circulating coolant of high boiling point.

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• Heat exchanger: High Pressure heated Coolant transfer the heat to the water flowing in heat exchanger & generates steam.
• Steam turbine: In steam turbine, the high pressurized steam from the heat exchanger is expanded on turbine blades develops mechanical Energy.

• Generator: The shaft of the steam turbine is connected to the shaft of the generator & the mechanical energy of the steam turbine is converted into electrical energy.

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• Condenser: It condensate (vapour to liquid) the steam that comes out from the steam turbine. It converts the low-pressure steam to water. It is connected to the cooling tower.

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• Cooling Tower: It is a tower which contains cold water. Cold water is circulated into the condenser for the cooling of the residual steam from the turbine.

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• Coolant pump: After transferring the heat in heat exchanger Coolant is again returned back to the nuclear reactor with the help of a coolant pump.

8. Solar Power Plant

The device used to collect & concentrate solar energy is called as Solar Concentrating Collector. They are of two types:

1) Flat Plate Collector- (Low temp. range 70-80 oC)

2) Parabolic Collector -(Higher above Temp. 100 oC)

Solar Power Plant

• Flat Plate Collector: Sunlight Incident on Flat Plate collector heats the water flowing inside tube and temperature Range 70-80 0C can be achieved.

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• Heat Exchanger: Heat absorbed by the hot water in the Flat Plate Collector is transferred to the Liquid Freon (Low Boiling Point) in heat exchanger & produces Freon steam.

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• Turbine: A high pressure, high temperature Freon steam is expanded on turbine blades which develops mechanical energy, by rotating turbine shaft.

• Generator: The shaft of the turbine is connected to the shaft of the generator & the mechanical energy of the turbine is converted into electrical energy.

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• Condenser: The exhaust Freon steam from the turbine is condensed to liquid Freon in condenser and it is returned back to a heat exchanger with the help feed pump.

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• Water Feed Pump: After heat exchange in heat exchanger water is again returned back to Flat Plate collector with the help of the water feed pump.

9.Photovoltaic (PV) cell or Solar Cell

• A Solar cell or Photovoltaic cell: It is a device that converts the light energy directly into electricity by the photovoltaic effect. When a light incident on cell its electrical characteristics such as current, voltage & resistance changes. The voltage induced by the PV cell depends on the intensity of light incident on it.

10. Geothermal Power Plant

• Binary Cycle Power Stations

Binary cycle power stations are the most recent development, where fluid temperatures as low as 57 °C can be used. The moderately hot geothermal water is passed over a secondary fluid with a much lower boiling point than water.

11.Wind Energy

• Wind is caused by huge convection currents in the Earth’s atmosphere due to solar heat energy. The kinetic energy of wind (speed range 10-40 kmph) is used to drive wind turbine blades, produces electricity. Traditionally this energy was used for milling grain and pumping water but today is most commonly used to create electricity.

Parts of Wind Turbine

• Blades: The main part of the wind turbine is the blade. When the wind is flowing over blades it lifts and rotates blade and rotor.
• Gear box: It connects the low-speed shaft to the high-speed shaft and increases the rotational speeds. It is connected to the generator to produce electricity.
• Electromagnetic Generator: It produces AC electricity
• Nacelle: It is a box which is placed at top of the tower, contains the gear box, low and high-speed shafts, generator, controller, and brake.

Working of Wind Turbine

• A high-speed wind rotates turbine hence rotor which produces a torque on a low-speed shaft.

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• The low-speed shaft transfers the energy to a gearbox, high-speed shaft & generator, which are enclosed in the nacelle for protection.

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• The low-speed shaft connects to the gearbox, which has a set of gears that increase the output speed of the shaft to approximate speed of 1500 rpm of frequency 50 Hz.

12. Hydrogen Energy

• Hydrogen produces a large amount of energy by combustion. Hydrogen can be prepared from caustic soda commercially and economically.

• Hydrogen Fuel Cell

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A fuel cell is made up of an anode, a cathode & electrolyte (H2SO4 Acid or KOH Alkali). A fuel cell works by passing hydrogen through the anode and oxygen through the cathode.

13. Biomass Energy

• Biomass energy is the energy generated from organic material. Biomass resources are derived from cultivated fields, human/animal wastes and its conversion into liquid fuels.

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• Biofuels are combustible fuels created from biomass. Crops such as sugarcane and corn are used to create biofuels. And as plant matter can be regrown, it’s a renewable source of energy.

Biofuels are grouped into 3 categories:

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• First generation biofuels are produced from food crops for ethanol

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• Second generation biofuels produced from cellulosic materials such as wood grasses and inedible parts of plants.

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• Third generation biofuels are produced using the lipids production from algae.

Processes of Energy Conversion from Biomass

14. Tidal Energy

• Tidal energy is the energy obtained from tides which converts hydro energy into electricity.

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.

Tidal Power Plant

• Tidal energy is produced by the use of tidal energy generators. These large underwater turbines are placed in areas with high tidal movements &designed to capture the kinetic motion of the ebbing and surging of ocean tides to produce electricity.

15. Grades of Energy

• High-Grade Energy: Electrical and Chemical energy is high-grade energy, because this energy is concentrated in a small space. Even a small amount of electrical and chemical energy can do a great amount of work. The molecules or particles that store these forms of energy are highly ordered and compact and thus considered as high-grade energy.

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• Low-Grade Energy: Heat is low-grade energy. Heat energy can be used to do work such as heater boiling water, but it rapidly dissipates. The molecules, in which this type of energy is stored (air and water molecules), are more randomly distributed than the molecules of carbon in coal. This disordered state of the molecules and the dissipated energy are classified as low-grade energy

16. Pumps

• Pump is a device which converts mechanical energy of a motor into pressure & kinetic energy of the fluid. It transfers the fluid from a low level to higher level by converting mechanical energy into hydraulic energy.

Centrifugal Pump

• Centrifugal pump is a hydraulic machine which converts the mechanical energy into pressure energy by using centrifugal force acting on the fluid.

• All centrifugal pumps rotate usually at 1750 or 3500 RPM inside a casing. The impeller is always submerged in water, and when the pump is operational the impeller spins rapidly.

• Impeller-It is a rotor which is provided with a series of backward curved blades/ vanes. It is mounted on a shaft which is usually connected to motor. The motor provides the required input energy to rotate the impeller.

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• Casing-The impeller is enclosed in the watertight casing with a delivery pipe on one side and suction pipe on the suction side which are connected by the eye of impeller. It is designed in such a way that it helps in converting the K.E. of fluid into pressure energy.

• Suction pipe-The pipe which connect sump to eye of impeller is called suction pipe. The sump carries liquid to be lifted by the pump. The suction pipe at its inlet is provided with strainer & foot valve. The function of strainer is to prevent the entry of any waste material like sand, leaves etc. The foot valve is non-return valve which allows the flow of water only in upward direction.

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• Delivery pipe-The pipe which connects the outlet of pump to delivery point is called delivery pipe. A delivery valve is provided to regulate the supply of liquid from the pump to the delivery pipe.

17. Compressors

• A compressor is a mechanical device that increases the pressure of Air / gas by reducing its volume (Compressing) driven by the prime mover such as electric motor or IC engine. This compressed air is stored in storage tank called as receiver.

• Reciprocating Compressor

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Single acting reciprocating Compressor: A reciprocating compressor in which Suction & Compression takes place on only one side of piston is called Single Acting Reciprocating Compressor.

Classification of Compressors

• Reciprocating Compressor

• Suction Stroke- When the piston moves downwards, the pressure inside the cylinder falls below the atmospheric pressure. Due to this pressure difference the inlet valve gets opened and air is sucked into the cylinder, at inlet pressure until the piston completes the suction stroke.

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• Delivery stroke- When piston moves upwards, the pressure inside the cylinder goes on increasing, when it becomes greater than atmospheric pressure suction valve closes. Further upwards movement compresses air till it reaches the discharge pressure. At this stage, the discharge valve gets opened and air is delivered to the receiver.

18. Hydraulic Turbines

• A water / Hydraulic turbine is a rotary machine that converts kinetic energy and pressure energy of water into mechanical work.

• The main Components of Pelton wheel turbine are Nozzle, Runner, Bucket, Casing & Brake nozzle.
• Turbine rotor (runner) has a double cup shaped buckets attached uniformly on its periphery.
• The water stored at the high head is allowed to flow through the penstock (K.E.of water) and reaches the nozzle of the Pelton turbine.
• The nozzle increases the K.E. of the water and directs the water in the form of jet. The jet of water from the nozzle strikes the buckets (vanes) of the runner. This makes the runner to rotate at very high speed.

• Explain Steam (Thermal) Power Plant with Neat Sketch. State Advantages and Limitations

• Explain Use of Hydrogen as Source of Energy

• Explain Hydroelectric Power Plant with Neat Sketch

• Draw Neat Sketch of Parabolic Collector. State Advantages of it over Flat Plate Collector.

• Write Short Note on: Photovoltaic Cell

• With neat Sketch Explain Working of Hydrogen Fuel Cell.

• Determine the power in the wind if the wind speed is 20 m/s and blade length is 50 m

Air density ρ = 1.23 kg/m³.