REVIEW OF POWER PLANT

REVIEW OF POWER PLANT
Engr Charlton S. Inao

Technical Report on:
 Carnot Cycle
 Stirling Cycle
 Ericsson Cycle
 Brayton Cycle
 Rankine Cycle
 Otto Cycle
 Diesel Cycle

Carnot Cycle
The Carnot cycle is a theoretical thermodynamic cycle.
It is the most efficient cycle for converting a given
amount of thermal energy into work, or conversely,
creating a temperature difference (e.g. refrigeration) by
doing a given amount of work.

Carnot Cycle
A Carnot cycle acting as a
heat engine. The cycle
takes place between a hot
reservoir at temperature TH
and a cold reservoir at
temperature TC.

Calculation for Carnot cycle
 In general, the thermal efficiency, ηth, of any heat engine is defined as the
ratio of the network it does, W, to the heat input at the high temperature,
QH.
 Since energy is conserved according to the first law of thermodynamics and
energy cannot be be converted to work completely, the heat input, QH, must
equal the work done, W, plus the heat that must be dissipated as waste heat
QC into the environment. Therefore, we can rewrite the formula for thermal
efficiency as:
 Since QC = ∆S.TC and QH = ∆S.TH, the formula for this maximum efficiency
is:
where:
 is the efficiency of Carnot cycle, i.e. it is the ratio = W/QH of the work done by the engine to the heat
energy entering the system from the hot reservoir.
 TC is the absolute temperature (Kelvins) of the cold reservoir,
TH is the absolute temperature (Kelvins) of the hot reservoir.

Stirling Cycle
 Stirling cycle is a thermodynamic cycle upon which a
Stirling Engine works. Stirling engine is a closed cycle
regenerative heat engine. It works on either air or any
other gas.

Stirling cycle diagram
The idealized Stirling cycle consists of four
thermodynamic processes acting on the working
fluid (See diagram to right):
I.1-2 Isothermal heat addition (expansion).
II.2-3 Isochoric heat removal (constant
volume).
III.3-4 Isothermal heat removal
(compression).
IV.4-1 Isochoric heat addition (constant
volume).

Ericsson Cycle
The Ericsson engine working on the principle of Ericson cycle
comprises of the regenerator and the heat exchanger. The
efficiency of regenerative Ericsson and Stirling engines have been
found to be almost the same as Carnot engine, however, the
amount of work developed with gas as the working fluid has been
found to be insufficient due to low thermal conductivity of gas.

Ericsson Cycle Diagram
 The Ericsson cycle comprises of two isothermal and two constant pressure (isobaric) processes. The
addition of heat takes place during constant pressure as well as isothermal processes. Here are the
various processes of Ericsson cycle when applied to the piston and cylinder engine. Please refer to P-
V diagram given at the bottom:

Ericsson Cycle Diagram
1. Isothermal expansion and heat addition process 1-2: During
this process the air, which acts as a working fluid, is heated from the
externally added heat. The heat of the air increases at constant
temperature T1 and it expands. It is during this process that the work is
obtained from the engine.
3. Isothermal compression process 3-4: During this process the air
drawn into the engine is compressed at constant temperature, by
applying an intercooler. The pressurized air is then drawn into the air
storage tank.
2. Constant pressure or isobaric heat rejection process 2-3: The
air is then passed through the regenerator, where its temperature reduces
to T3 at constant pressure. The heat absorbed by the regenerator is used
for heating in the next part of the cycle. The air after passing through
the regenerator is released as the exhaust gas.
4. Constant pressure or isobaric heat absorption
process 4-1: The compressed air at high pressure passes
through the regenerator and absorbs the previously stored
heat. It then flows to the piston and cylinder where it gets
expanded and produces work during process 1-2. Thus,
the cycle keeps on repeating.

Brayton Cycle
 The Brayton cycle is a thermodynamic cycle named after
George Brayton that describes the workings of a constant-
pressure heat engine. The original Brayton engines used a
piston compressor and piston expander, but more modern gas
turbine engines and airbreathing jet engines also follow the
Brayton cycle.

Brayton cycle diagram
The idealized Brayton cycle where P = pressure, V = volume, T = temperature, S = entropy, and Q = the heat added to or rejected by the system.
Ideal Brayton cycle:
1. isentropic process – ambient air is drawn
into the compressor, where it is pressurized.
2. isobaric process – the compressed air then
runs through a combustion chamber, where
fuel is burned, heating that air—a constant-
pressure process, since the chamber is open
to flow in and out.
3. isentropic process – the heated, pressurized
air then gives up its energy, expanding
through a turbine (or series of turbines).
Some of the work extracted by the turbine
is used to drive the compressor.
4. isobaric process – heat rejection (in the
atmosphere).
Actual Brayton cycle:
1. adiabatic process – compression
2. isobaric process – heat addition
3. adiabatic process – expansion
4. isobaric process – heat rejection

Brayton cycle formula
To find the efficiency of the Brayton Cycle, we must find out how much work each process contributes to the total internal
energy. We will be analyzing the PV diagram above to do this.
First, the internal energy
U=q1+q2−w=0
is equal to zero because the first law of thermodynamics states that energy is not destroyed or created, and because in the
Brayton cycle the final state function of the gas is the initial, U = 0.
This means
w=q1+q2
where q1 is the heat received by the combustion (so it is negative) and q2 is the heat released after expansion.
If you treat the gas as a perfect gas with constant specific heats, we can find the heat addition from the combuster to be
q1=cp(TI−TF)
and the heat lost to the atmosphere
q2=cp(TF−TI)
Where TF is the final temperature of the combustion or "heat lost to the atmosphere" part and the latter is the initial. (So, in the
PV curve, the combustion process would have q1=cp(T4−T3)

Brayton cycle formula
So now we have expressed the amount of heat lost and gained in terms of temperatures, we can re-establish
the equation to find eta (thermal efficiency)
where c is the final temperature of the combustion process and b is the initial temperature before combustion
and a is the initial temperature of the undisturbed gas and d is the temperature of the gas after it has been
expelled. The corresponding numbers to letters from the PV graph are a = 2; b = 3; c = 4; d = 6.
The smaller the temperature ratio is the higher the efficiency of the Brayton’s cycle is. So that is, the more
heat input into the system and the smaller amount of heat lost to the atmosphere will significantly reduce the
temperature ratio and have a higher percentage of efficiency.

Rankine Cycle
The Rankine cycle closely describes the process by which steam-
operated heat engines commonly found in thermal power generation
plants generate power.
Power depends on the temperature difference between a heat source and
a cold source. The higher the difference, the more mechanical power can
be efficiently extracted out of heat energy, as per Carnot's theorem.
The heat sources used in these power plants are usually nuclear fission
or the combustion of fossil fuels such as coal, natural gas, and oil, or
concentrated solar power. The higher the temperature, the better.

Rankine Cycle Diagram
The pressure-enthalpy (p-h) and temperature-entropy (T-s) diagrams of this cycle are given in Figure. The Rankine cycle
operates in the following steps:
 1-2-3 Isobaric Heat Transfer. High pressure liquid enters the boiler from the feed pump (1) and is heated to the saturation
temperature (2). Further addition of energy causes evaporation of the liquid until it is fully converted to saturated steam
(3).
 3-4 Isentropic Expansion. The vapor is expanded in the turbine, thus producing work which may be converted to
electricity. In practice, the expansion is limited by the temperature of the cooling medium and by the erosion of the turbine
blades by liquid entrainment in the vapor stream as the process moves further into the two-phase region. Exit vapor
qualities should be greater than 90%.
 4-5 Isobaric Heat Rejection. The vapor-liquid mixture leaving the turbine (4) is condensed at low pressure, usually in a
surface condenser using cooling water. In well designed and maintained condensers, the pressure of the vapor is well
below atmospheric pressure, approaching the saturation pressure of the operating fluid at the cooling water temperature.
 5-1 Isentropic Compression. The pressure of the condensate is raised in the feed pump. Because of the low
specific volume of liquids, the pump work is relatively small and often neglected in thermodynamic
calculations.

Rankine cycle formula
In general, the efficiency of a simple Rankine cycle can be written as
Each of the next four equations is derived from the energy and mass
balance for a control volume. ntherm defines the thermodynamic
efficiency of the cycle as the ratio of net power output to heat input. As
the work required by the pump is often around 1% of the turbine work
output, it can be simplified.
When dealing with the efficiencies of the turbines and pumps, an
adjustment to the work terms must be made:

Otto Cycle
An Otto cycle is an idealized thermodynamic cycle that describes the functioning of
a typical spark ignition piston engine. It is the thermodynamic cycle most commonly
found in automobile engines.

Otto Cycle diagram
Otto Thermodynamic Cycle which is used in all internal combustion engines.
The figure shows a p-V diagram of the Otto cycle. Using the engine stage
numbering system, we begin at the lower left with:
 Stage 1 being the beginning of the intake stroke of the engine. The pressure is
near atmospheric pressure and the gas volume is at a minimum. Between
Stage 1 and Stage 2 the piston is pulled out of the cylinder with the intake
valve open. The pressure remains constant, and the gas volume increases as
fuel/air mixture is drawn into the cylinder through the intake valve.
 Stage 2 begins the compression stroke of the engine with the closing of the
intake valve. Between Stage 2 and Stage 3, the piston moves back into the
cylinder, the gas volume decreases, and the pressure increases because work
is done on the gas by the piston.
 Stage 3 is the beginning of the combustion of the fuel/air mixture. The
combustion occurs very quickly and the volume remains constant. Heat is
released during combustion which increases both the temperature and the
pressure, according to the equation of state.

Otto Cycle diagram
 Stage 4 begins the power stroke of the engine. Between Stage 4 and Stage 5, the piston is driven towards
the crankshaft, the volume in increased, and the pressure falls as work is done by the gas on the piston.
 At Stage 5 the exhaust valve is opened and the residual heat in the gas is exchanged with the surroundings.
The volume remains constant and the pressure adjusts back to atmospheric conditions.
 Stage 6 begins the exhaust stroke of the engine during which the piston moves back into the cylinder, the
volume decreases and the pressure remains constant. At the end of the exhaust stroke, conditions have
returned to Stage 1 and the process repeats itself.

Diesel Cycle
The Diesel cycle is a combustion process of a reciprocating internal combustion engine. In it,
fuel is ignited by heat generated during the compression of air in the combustion chamber, into
which fuel is then injected. This is in contrast to igniting the fuel-air mixture with a spark plug as in
the Otto cycle (four-stroke/petrol) engine. Diesel engines are used in aircraft, automobiles, power
generation, diesel-electric locomotives, and both surface ships and submarines.
The Diesel cycle is assumed to have constant pressure during the initial part of the combustion
phase (V2 to V3 in the diagram, below). This is an idealized mathematical model: real physical
diesels do have an increase in pressure during this period, but it is less pronounced than in the Otto
cycle. In contrast, the idealized Otto cycle of a gasoline engine approximates a constant volume
process during that phase.

Diesel cycle diagram
The image shows a p-V diagram for the ideal Diesel cycle;
where p is pressure and V the volume or v the specific volume if
the process is placed on a unit mass basis. The idealized Diesel
cycle assumes an ideal gas and ignores combustion chemistry,
exhaust- and recharge procedures and simply follows four
distinct processes:
 1→2 : isentropic compression of the fluid (blue)
 2→3 : reversible constant pressure heating (red)
 3→4 : isentropic expansion (yellow)
 4→1 : reversible constant volume cooling (green)

The Diesel engine is a heat engine: it converts heat into work. During the bottom isentropic processes (blue), energy is
transferred into the system in the form of work Win, but by definition (isentropic) no energy is transferred into or out of the
system in the form of heat. During the constant pressure (red, isobaric) process, energy enters the system as heat Qin.
During the top isentropic processes (yellow), energy is transferred out of the system in the form of Wout, but by definition
(isentropic) no energy is transferred into or out of the system in the form of heat. During the constant volume (green,
isochoric) process, some of energy flows out of the system as heat through the right depressurizing process Qout. The work
that leaves the system is equal to the work that enters the system plus the difference between the heat added to the system
and the heat that leaves the system; in other words, net gain of work is equal to the difference between the heat added to the
system and the heat that leaves the system.
 Work in (Win) is done by the piston compressing the air (system)
 Heat in (Qin) is done by the combustion of the fuel
 Work out (Wout) is done by the working fluid expanding and pushing a piston (this produces usable work)
 Heat out (Qout) is done by venting the air
 Net work produced = Qin – Qout

The net work produced is also represented by the area enclosed by the cycle on the P-V diagram. The net
work is produced per cycle and is also called the useful work, as it can be turned to other useful types of energy
and propel a vehicle (kinetic energy) or produce electrical energy. The summation of many such cycles per unit
of time is called the developed power. The Wout is also called the gross work, some of which is used in the next
cycle of the engine to compress the next charge of air

Diesel Cycle Formula
The maximum thermal efficiency of a Diesel cycle is dependent on the compression ratio and the cut-
off ratio. It has the following formula under cold air standard analysis:

Diesel Cycle Formula
T3 can be approximated to the flame temperature of the fuel used. The flame temperature can be approximated to the
adiabatic flame temperature of the fuel with corresponding air-to-fuel ratio and compression pressure, p3 . T1 can be
approximated to the inlet air temperature.
This formula only gives the ideal thermal efficiency. The actual thermal efficiency will be significantly lower due to heat
and friction losses. The formula is more complex than the Otto cycle (petrol/gasoline engine) relation that has the following
formula:
The additional complexity for the Diesel formula comes around since the heat addition is at constant pressure and the heat
rejection is at constant volume. The Otto cycle by comparison has both the heat addition and rejection at constant volume.

Technical Report on:
 Internal Combustion
 Diesel Engine
 Gas/ Petrol Engine
 Steam Turbine
 Gas Turbine
 Condenser
 Evaporator
 Refrigerator
 Split Type Air Conditioner
 Chiller Evaporative Condenser
 Cooling Tower
 Ice plant
 Coal Power plant
 Diesel Power plant
 Gas Turbine Power plant
 Steam Power plant
 Hydropower plant
 Geothermal Power plant
 Nuclear Power plant
 Solar Power plant
 Wind Power plant
 Waste Power plant

Internal Combustion Engine
 It is an engine that generates motive power by the burning of gasoline, oil, or other fuel with
air inside the engine, the hot gases produced being used to drive a piston or do other work as
they expand. This force moves the component over a distance, transforming chemical energy
into useful mechanical energy.
 The first commercially successful internal combustion engine was created by Étienne Lenoir
around 1859 and the first modern internal combustion engine was created in 1876 by
Nikolaus Otto. Internal Combustion Engines (ICE) are the most common form of heat
engines, as they are used in vehicles, boats, ships, airplanes, and trains. They are named as
such because the fuel is ignited in order to do work inside the engine. The same fuel and air
mixture are then emitted as exhaust.

How does this engine work?
Combustion, also known as burning, is the basic chemical
process of releasing energy from a fuel and air mixture. In an internal
combustion engine (ICE), the ignition and combustion of the fuel
occurs within the engine itself. The engine then partially converts the
energy from the combustion to work. The engine consists of a fixed
cylinder and a moving piston. The expanding combustion gases push
the piston, which in turn rotates the crankshaft. Ultimately, through a
system of gears in the powertrain, this motion drives the vehicle’s
wheels.
There are two kinds of internal combustion engines currently in
production: the spark ignition gasoline engine and the compression
ignition diesel engine. Most of these are four-stroke cycle engines,
meaning four piston strokes are needed to complete a cycle. The cycle
includes four distinct processes: intake, compression, combustion and
power stroke, and exhaust.

How does this engine work?
Spark ignition gasoline and compression ignition diesel engines differ in how they supply
and ignite the fuel. In a spark ignition engine, the fuel is mixed with air and then inducted into
the cylinder during the intake process. After the piston compresses the fuel-air mixture, the
spark ignites it, causing combustion. The expansion of the combustion gases pushes the piston
during the power stroke. In a diesel engine, only air is inducted into the engine and then
compressed. Diesel engines then spray the fuel into the hot compressed air at a suitable,
measured rate, causing it to ignite.

Diesel Engine
Like a gasoline engine, a diesel engine is a type of internal combustion engine.
Combustion is another word for burning, and internal means inside, so an internal combustion
engine is simply one where the fuel is burned inside the main part of the engine (the cylinders)
where power is produced. That's very different from an external combustion engine such as
those used by old-fashioned steam locomotives. In a steam engine, there's a big fire at one end
of a boiler that heats water to make steam. The steam flows down long tubes to a cylinder at
the opposite end of the boiler where it pushes a piston back and forth to move the wheels. This
is external combustion because the fire is outside the cylinder (indeed, typically 6-7 meters or
20-30ft away). In a gasoline or diesel engine, the fuel burns inside the cylinders themselves.
Internal combustion wastes much less energy because the heat doesn't have to flow from
where it's produced into the cylinder: everything happens in the same place. That's why
internal combustion engines are more efficient than external combustion engines (they
produce more energy from the same volume of fuel).

How does a Diesel Engine work?
A diesel engine works differently
from a petrol engine, even though they
share major components and both work
on the four-stroke cycle. The main
differences are in the way the fuel is
ignited and the way the power output
is regulated.
In a petrol engine, the fuel/air
mixture is ignited by a spark. In a diesel
engine, ignition is achieved by
compression of air alone.
A typical compression ratio for a diesel engine is 20:1, compared with 9:1 for a petrol engine. Compressions as great as this
heat up the air to a temperature high enough to ignite the fuel spontaneously, with no need of a spark and therefore of an
ignition system.
A petrol engine draws in variable amounts of air per suction stroke, the exact amount depending on the throttle opening. A
diesel engine, on the other hand, always draws in the same amount of air (at each engine speed), through an unthrottled inlet
tract that is opened and closed only by the inlet valve (there is neither a carburetor nor a butterfly valve).

How does a Diesel Engine work?
When the piston reaches the effective end of its induction stroke, the inlet valve closes.
The piston, carried round by the power from the other pistons and the momentum of the
flywheel, travels to the top of the cylinder, compressing the air into about a twentieth of its
original volume.
As the piston reaches the top of its travel, a precisely metered quantity of diesel fuel is
injected into the combustion chamber. The heat from compression fires the fuel/air mixture
immediately, causing it to burn and expand. This forces the piston downwards, turning the
crankshaft.
As the piston moves up the cylinder on the exhaust stroke, the exhaust valve opens and
allows the burned and expanded gases to travel down the exhaust pipe. At the end of the
exhaust stroke the cylinder is ready for a fresh charge of air.

Gas or Petrol Engine
A gasoline engine is a type of heat engine, specifically an internal combustion, that is
powered by gasoline. These engines are the most common ways of making motor vehicles
move. While turbines can be powered by gasoline, a gasoline engine refers specifically to
piston-driven gasoline engines.
Gasoline engines are a lot of the reason why the world takes so much oil out of the
ground to refine into petroleum products like gasoline. Worldwide, transportation is
roughly 18% of our primary energy use and gasoline is a little less than half of that.[2] This
means that gasoline engines use roughly 8% of the total primary energy of the world.

How does a Gasoline or Petrol Engine work?
Spark ignition gasoline and compression ignition
diesel engines differ in how they supply and ignite the
fuel. In a spark ignition engine, the fuel is mixed with air
and then inducted into the cylinder during the intake
process. After the piston compresses the fuel-air mixture,
the spark ignites it, causing combustion. The expansion of
the combustion gases pushes the piston during the power
stroke. In a diesel engine, only air is inducted into the
engine and then compressed. Diesel engines then spray
the fuel into the hot compressed air at a suitable,
measured rate, causing it to ignite.

Steam Turbine
In general, a steam turbine is a rotary heat engine that converts thermal energy contained
in the steam to mechanical energy or to electrical energy. In its simplest form, a steam turbine
consist of a boiler (steam generator), turbine, condenser, feed pump and a variety of
auxiliary devices. Unlike with reciprocating engines, for instance, compression, heating and
expansion are continuous and they occur simultaneously. The basic operation of the steam
turbine is similar to the gas turbine except that the working fluid is water and steam instead of
air or gas.
Since the steam turbine is a rotary heat engine, it is particularly suited to be used to drive
an electrical generator. Note that about 90% of all electricity generation in the world is by use
of steam turbines. Steam turbine was invented in 1884 by Sir Charles Parsons, whose first
model was connected to a dynamo that generated 7.5 kW (10 hp) of electricity. Steam turbine
is a common feature of all modern and also future thermal power plants. In fact, also the
power production of fusion power plants is based on the use of conventional steam turbines.

How does a Steam Turbine work?
The thermal energy contained in the steam is converted to the mechanical energy by expansion through
the turbine. The expansion takes place through a series of fixed blades (nozzles), that orient the steam
flow into high speed jets. These jets contain significant kinetic energy, which is converted into shaft
rotation by the bucket-like shaped rotor blades, as the steam jet changes direction. The steam jet, in
moving over the curved surface of the blade, exerts a pressure on the blade owing to its centrifugal force.
Each row of fixed nozzles and moving blades is called a stage. The blades rotate on the turbine rotor and
the fixed blades are concentrically arranged within the circular turbine casing.
In all turbines the rotating blade velocity is proportional to the steam velocity passing over the
blade. If the steam is expanded only in a single stage from the boiler pressure to the exhaust pressure, its
velocity must be extremely high. But the typical main turbine in nuclear power plants, in which steam
expands from pressures about 6 MPa to pressures about 0.008 MPa, operates at speeds about 3,000 RPM
for 50 Hz systems for 2-pole generator.(or 1500RPM for 4-pole generator), and 1800 RPM for 60 Hz
systems for 4-pole generator (or 3600 RPM for 2-pole generator). A single-blade ring would require very
large blades and approximately 30 000 RPM, which is too high for practical purposes.

How does a Steam Turbine work?
Therefore, most of nuclear power plants
operates a single-shaft turbine-generator that
consists of one multi-stage HP turbine and three
parallel multi-stage LP turbines, a main generator
and an exciter. HP Turbine is usually double-flow
reaction turbine with about 10 stages with
shrouded blades and produces about 30-40% of the
gross power output of the power plant unit. LP
turbines are usually double-flow reaction turbines
with about 5-8 stages (with shrouded blades and
with free-standing blades of last 3 stages). LP
turbines produce approximately 60-70% of the gross
power output of the power plant unit. Each turbine
rotor is mounted on two bearings, i.e. there are
double bearings between each turbine module.

Gas Turbine
A gas turbine is a type of turbine that uses pressurized gas to spin it in
order to generate electricity or provide kinetic energy to an airplane or jet. The
process to do so is called the Brayton cycle. In all modern gas turbines, the
pressurized gas is created by the burning of a fuel like natural gas, kerosene,
propane or jet fuel. The heat generated by this fuel expands air which flows
through the turbine to supply useful energy.

How does a Gas Turbine work?
Gas turbines are theoretically simple, and have
three main parts:
1. Compressor- Takes in air from outside of
the turbine and increases its pressure.
2. Combustor- Burns the fuel and produces
high pressure and high velocity gas.
3. Turbine- Extracts the energy from the gas
coming from the combustor.

How does a Gas Turbine work?
Compressor
In Figure, air is sucked in from the left and input to the compressor which consists of many rows of
fan blades. In some turbines, the pressure of the air can increase by a factor of 30.
Combustor
The high-pressure air flows into this area, which is where the fuel is introduced. The fuel gets
injected constantly into this part in order for the energy through the turbine to be constant.
Turbine
The turbine is connected to the compressor blades by a shaft, and they spin separately. The
compressor connects to the turbine which is connected to an output shaft, and because the turbine spins
separately, it can get up to tremendous speeds due to the hot gas flowing through it. This final shaft
generates enormous amounts of horsepower, with large airplane turbines generating nearly 110000 hp -
twice the power generated by the Titanic.

Condenser
Condenser, device for reducing a gas or vapour to a liquid. Condensers are employed in
power plants to condense exhaust steam from turbines and in refrigeration plants to condense
refrigerant vapours, such as ammonia and fluorinated hydrocarbons. The petroleum and
chemical industries employ condensers for the condensation of hydrocarbons and other
chemical vapours. In distilling operations, the device in which the vapour is transformed to a
liquid state is called a condenser.
All condensers operate by removing heat from the gas or vapour; once sufficient heat is
eliminated, liquefaction occurs. For some applications, all that is necessary is to pass the gas
through a long tube (usually arranged in a coil or other compact shape) to permit heat to escape
into the surrounding air. A heat-conductive metal, such as copper, is commonly used to
transport the vapour. A condenser’s efficiency is often enhanced by attaching fins (i.e., flat sheets
of conductive metal) to the tubing to accelerate heat removal. Commonly, such condensers
employ fans to force air through the fins and carry the heat away. In many cases, large
condensers for industrial applications use water or some other liquid in place of air to achieve
heat removal.

How does a Condenser work?
The condenser coil is where the heat gets removed. The consolidating unit
(some of the time inaccurately known as compressor) is situated outside. Its original
capacity is that of a warmth exchanger, in which it gathers a substance (refrigerant)
from it’s vaporous to the molten state. From that point, the latent heat is surrendered
by the content and will exchange to the condenser coolant. In the refrigeration cycle,
a warmth pump transfers warm from a low-temperature close source into a higher
temperature warm sink.
Warm streams the other way as a result of the second law of thermodynamics.
The most well-known of the refrigeration cycles utilizes an electric engine to drive a
compressor (situated inside the consolidating unit). Since dissipation happens when
warmth is retained, and buildup occurs when heat is discharged, aeration and
cooling systems are intended to utilize a compressor to cause weight changes
between two compartments, and effectively draw refrigerant around.
Inside the condenser, the refrigerant vapor is compacted and constrained through a
warmth trade loop, gathering it into a fluid and dismissing the heat already retained
from the cold indoor zone. The condenser’s heat exchanger is for the most part
cooled by a fan blowing outside air through it.

Evaporator
The evaporator works the opposite of the condenser, here refrigerant liquid is converted to gas, absorbing heat
from the air in the compartment.
When the liquid refrigerant reaches the evaporator, its pressure has been reduced, dissipating its heat content
and making it much cooler than the fan air flowing around it. This causes the refrigerant to absorb heat from the
warm air and reach its low boiling point rapidly. The refrigerant then vaporizes, absorbing the maximum amount of
heat.
This heat is then carried by the refrigerant from the evaporator as a low-pressure gas through a hose or line to
the low side of the compressor, where the whole refrigeration cycle is repeated.
The evaporator removes heat from the area that is to be cooled. The desired temperature of cooling of the area
will determine if refrigeration or air conditioning is desired. For example, food preservation generally requires low
refrigeration temperatures, ranging from 40°F (4°C) to below 0°F (-18°C).
A higher temperature is required for human comfort. A larger area is cooled, which requires that large volumes
of air be passed through the evaporator coil for heat exchange. A blower becomes a necessary part of the evaporator
in the air conditioning system. The blower fans must not only draw heat-laden air into the evaporator, but must also
force this air over the evaporator fins and coils where it surrenders its heat to the refrigerant and then forces the
cooled air out of the evaporator into the space being cooled.

How does an Evaporator work?
The air conditioners compressor
changes the refrigerant gas to a liquid
under high pressure. The liquid
refrigerant flows into the evaporator
through a very tiny orifice. As the
liquid enters the evaporator and
progresses through its coils, it picks
up heat from the air passing through
it, causing it to evaporate, thus
cooling the room.

Refrigeration
Refrigeration, or cooling process, is the removal of unwanted heat from a selected object,
substance, or space and its transfer to another object, substance, or space. Removal of heat lowers the
temperature and may be accomplished by use of ice, snow, chilled water or mechanical refrigeration.
Refrigeration is the process of removing heat from an enclosed space, or from a substance, and
rejecting it elsewhere for the primary purpose of lowering the temperature of the space or substance
and then maintaining that lower temperature. The term cooling refers generally to any natural or
artificial process by which heat is dissipated. The field of study that deals with artificial production
of extremely low temperatures is referred to as cryogenics.
Cold is the absence of heat, hence in order to decrease a temperature, one "removes heat," rather
than "adding cold." To satisfy the Second Law of Thermodynamics, some form of work must be
performed when removing heat. This work is traditionally mechanical work, but it can also be done
by magnetism, laser, or other means.

How does a Refrigeration work?

How does a Refrigeration work?
1. The compressor constricts the refrigerant vapor, raising its pressure and temperature, and
pushes it into the coils of the condenser on the outside of the refrigerator.
2. When the hot gas in the coils of the condenser meets the cooler air temperature of the kitchen, it
becomes a liquid.
3. Now in liquid form at high pressure, the refrigerant cools down as it flows through the
expansion valve into the evaporator coils inside the freezer and the fridge.
4. The refrigerant absorbs the heat inside the fridge when it flows through the evaporator coils,
cooling down the air inside the fridge.
5. Last, the refrigerant evaporates to a gas due to raised temperature, and then flows back to the
compressor, where the cycle starts all over again.
The main component of a refrigerator that needs power is the compressor. It is essentially a pump
which is driven by a motor. The hum you hear when the fridge is on is that of the compressor
working. The thermostat controls the temperature of the fridge by switching on-and-off the
compressor.

Split Type Air Conditioner
When someone refers to a split air conditioner, they are referring to the way in
which the unit is set up. A split air conditioner is composed of two separate units, a
condensing unit and an evaporative coil (known as a “condenser,” and a “coil”
respectively in short-hand or slang). It is from these two separate units that a split air
conditioner gets its name. These units are joined by a set of copper tubing known as a
“line-set,” which transfers refrigerant from one unit to another.
A split air conditioner consists of an outdoor unit and an indoor unit. The outdoor
unit is installed on or near the exterior wall of the room that you wish to cool. This unit
houses the compressor, condenser coil and the expansion coil or capillary tubing. The
sleek-looking indoor unit contains the cooling coil, a long blower and an air filter.

How does a Split Type Air Conditioner work?
A split air conditioner is made up of two primary
parts that a very familiar: the evaporator and the
compressor. Both of these elements exist is more common
central air units and wall air conditioners. The difference
with a mini-split system is that they are separated into
two different, distant components, one being outdoors
and one being indoors. The outdoor section is a
compressor that initiates the cooling process, while the
indoor component consists of an evaporator and fan.
The two sections are connected with a set of electrical
wires and tubing, also called lines, used to transport air
between the two sections. It's these lines that allow the
split AC to be considered ductless, and the fact that the
wires and tubing are so small and discreet compared to
large ducts is where the "mini" split name comes from.

Chiller / Evaporative Condenser
An evaporative condenser is used to remove excess heat from a cooling system
when the heat cannot be utilized for other purposes. The excess heat is removed by
evaporating water.
The evaporative condenser has a cabinet with a water-sprayed condenser, and
it usually has one or more fans. The excess heat is removed by evaporating water.
In an evaporative condenser the primary coolant of the cooling system is cooled,
which is the opposite of a cooling tower. Evaporator condensers are more
expensive than dry coolers and are primarily used in large cooling systems or
systems where the outdoor temperature is high. In many locations around the
world, regulations limit the physical size of a cooling system and this in turn limits
the use of evaporative condensers.
Spraying a condenser with water exploits the fact that the dew point
temperature is lower than the air temperature and that a wet surface transfers heat
more efficiently.

How does a Chiller work?
Evaporative Condenser is also named Evaporative Cooler. It’s a type of cooling equipment
utilizing the evaporation of partial spray water, to absorb the heat from the flowing gaseous
refrigerant of high temperature inside the condensing coils, and cool the refrigerant from gaseous
state to liquid form. In an evaporative cooling system, compressor discharges high pressure
evaporated refrigerant in gas form, which passes through the heat exchange coils of evaporative
condenser, and exchanges heat with spray water outside the heat exchange coils. After entering
heat exchange coils from upper inlet, gaseous refrigerant is gradually cooled to be liquid form
from top down. The strong wind of fans makes spray water fully cover the heat exchange coil
evenly, and this tremendously increases the heat exchange efficiency. Partial calefactive spray
water gets vaporized and takes away massive heat with the air flow. Small water drops in hot air
are intercepted by highly efficient drift eliminator, collected and fall back to PVC fill together with
hot spray water, then gets cooled by flowing air, eventually return to the spray water basin after
temperature decreased. This whole process is recycling by the circulating pump when the
evaporative condensers are working. The evaporated spray water is made up automatically by
water level regulator.

Cooling Tower
A cooling tower is a heat rejection device, which extracts waste heat to the
atmosphere though the cooling of a water stream to a lower temperature. The type of
heat rejection in a cooling tower is termed "evaporative" in that it allows a small portion
of the water being cooled to evaporate into a moving air stream to provide significant
cooling to the rest of that water stream. The heat from the water stream transferred to the
air stream raises the air's temperature and its relative humidity to 100%, and this air is
discharged to the atmosphere. Evaporative heat rejection devices such as cooling towers
are commonly used to provide significantly lower water temperatures than achievable
with "air cooled" or "dry" heat rejection devices, like the radiator in a car, thereby
achieving more cost-effective and energy efficient operation of systems in need of
cooling. Think of the times you've seen something hot be rapidly cooled by putting water
on it, which evaporates, cooling rapidly, such as an overheated car radiator. The cooling
potential of a wet surface is much better than a dry one.

How Does a Cooling Tower work?
Cooling towers are a special type of heat exchanger that allows water
and air to come in contact with each other to lower the temperature of the hot
water. During this process, small volumes of water evaporate, lowering the
temperature of the water that’s being circulated throughout the cooling
tower. In a short summary, a cooling tower cools down water that gets over
heated by industrial equipment and processes.
The hot water is usually caused by air conditioning condensers or other
industrial processes. That water is pumped through pipes directly into the
cooling tower. Cooling tower nozzles are used to spray the water onto to the
“fill media”, which slows the water flow down and exposes the maximum
amount of water surface area possible for the best air-water contact. The
water is exposed to air as it flows throughout the cooling tower. The air is
being pulled by an motor-driven electric “cooling tower fan”.
When the air and water come together, a small volume of water
evaporates, creating an action of cooling. The colder water gets pumped back
to the process/equipment that absorbs heat or the condenser. It repeats the
loop over and over again to constantly cool down the heated

Ice plant
How does it work?
The function of an ice plant or ice factory is to make or form ice in large quantity and in large size. The ice
making process is quite similar to the one we observe in a domestic refrigerator. The only difference lies in the
ice making the stage. In the freezer compartment, the tray with water when it comes in contact with very low-
temperature environment, becomes ice but in an ice plant which is a huge commercial factory, it uses separate
ice making or ice freezing circuit. The cold is produced in one circuit and it is transferred to the water cans by
another circuit.
 Ammonia: It is the primary refrigerant which takes heat from brine. This ammonia changes phase while
moving in the circuit.
 Brine: It is the secondary refrigerant which takes heat from the water and produces ice.
There are three main circuits of working medium in ice plant:
1. Refrigeration circuit: Ammonia as working medium which actually produces the cold by changes its
phase at different location
2. Cooling water circuit: Cooling water as working medium to remove the heat of condenser
3. Brine circuit: Brine solution as working medium which transfers the cold from ammonia to water filled
cans where ice is to be formed.

Ice plant
Construction
 Construction Compressor: Its function is to increase the
temperature and pressure of Ammonia vapor coming out from
evaporator.
 Condenser: It liquefies the high-pressure and high-temperature Ammonia to high-
pressure and high-temperature Ammonia. Here chilled water comes in contact
with the high-pressure and high-temperature ammonia and provides the
temperature for condensation. The heated water is pumped and again taken to
circuit after it has been cooled at natural cooling tower
 Receiver: It is used to collect the liquid Ammonia from the condenser.
 Throttle Valve: It expands Ammonia coming out from receiver to low pressure.
 Evaporator: It vaporize the liquid Ammonia from throttle valve by extracting heat
from 'brine' and hence brine gets cooled and this brine solution is recirculated to
water tank containing 'ice cans filled with water' to absorb the heat of water to
freeze it and make ice.

Ice plant
Working
 Low pressure and low-temperature Ammonia
coming out from the throttle valve is vaporized by
taking the latent heat from the brine. Hence brine
gets cooled which is circulated in the brine circuit
to freeze the water and forming an ice from water.
 This cooled brine further absorbs the heat from
water and converts water to ice.
 Vaporized Ammonia is compressed to high
pressure and temperature and passes from
condenser.
 In condenser Ammonia is condensed by water
circulated in cooling water circuit having a natural
cooling tower. The condenser condenses the
Ammonia by water coming from natural cooling
tower.

Coal Power Plant
More than half of the electricity generated in the world is
by using coal as the primary fuel. The function of the coal fired
thermal power plant is to convert the energy available in the
coal to Electricity. Coal power plants work by using several
steps to convert stored energy in coal to usable electricity that
we find in our home that powers our lights, computers, and
sometimes, back into heat for our homes.

How Coal Power Plants Produce Electricity?
Stage 1
The first conversion of energy takes place in the boiler. Coal is burnt in the boiler
furnace to produce heat. Carbon in the coal and Oxygen in the air combine to produce
Carbon Dioxide and heat.
Stage 2
The second stage is the thermodynamic process.
1.The heat from combustion of the coal boils water in the boiler to produce steam. In
modern power plant, boilers produce steam at a high pressure and temperature.
2.The steam is then piped to a turbine.
3.The high pressure steam impinges and expands across a number of sets of blades in
the turbine. 4.The impulse and the thrust created rotates the turbine.
5.The steam is then condensed and pumped back into the boiler to repeat the cycle.
Stage 3 In the third stage, rotation of the turbine rotates the generator rotor to produce
electricity based of Faraday’s Principle of electromagnetic induction.

How Coal Power Plants Produce Electricity?

Diesel Power Plant
A Diesel power station (also known as Stand-by power station)
uses a diesel engine as prime mover for the generation of electrical
energy. This power station is generally compact and thus can be
located where it is actually required. This kind of power station can
be used to produce limited amounts of electrical energy. In most
countries these power stations are used as emergency supply
stations.

How does an Diesel Power plant work?
The diesel burns inside the engine and the
combustion process moves a fluid that turns the
engine shaft and drives the alternator. The
alternator in turn, converts mechanical energy into
electrical energy.
This type of electricity generating power station will
probably be used a long time into the future, due to
a need for reliable stand-by electrical source for
emergency situations.
However, diesel power plants emit greenhouse gases
that pollute the environment and also require
frequent servicing.

Gas Turbine Power Plant
In today’s world, a vast amount of
resources is rightfully devoted to
discovering newer, more efficient, and
more affordable ways to create energy.
Although early versions of gas
turbines were created as early as the
year 50 AD, the gas turbine as a major
power producer came about just
before the turn of the 20th century,
and they are continually being
improved to provide reliable energy
communities around the world today.
Parts of a Gas Turbine
Although the operations of a gas turbine are
complex, there are three essential parts: the
compressor, the combustion system, and the
turbine. The compressor works by pulling air into
the engine, which is then pressurized and fed into
the combustion chamber at up to several hundreds
of miles per hour. The combustion system uses fuel
injectors to inject natural gas into the combustion
chamber, resulting in temperatures of over 2,000
degrees Fahrenheit. Finally, the combusting gas
enters the turbine, where it spins rotating blades
that in-turn spin a generator, producing electricity
for different energy market. This process also pulls
more air into the compressor, restarting the process.

Types of Gas Turbines
Although gas turbines all operate with the same
main process, there are differences between two
major types of turbines: heavy frame engines and
aeroderivative engines. One main difference is in the
pressure ratio, which is the ratio between compressor
discharge pressure and inlet air pressure. While the
pressure ratio for heavy frame engines is normally
below 20 psi, it is generally in excess of 30 psi when it
comes to aeroderivative engines. Another difference is
that aeroderivative engines are generally compact and
used when less energy is required, and heavy frame
engines are larger and have much higher power
generation. However, this also means they have
higher emissions, and therefore must be designed
differently to reduce emissions of pollutants such as
NOx.

Gas Turbine Controls
Because gas turbines have such a massive output of energy, advanced
control systems and solutions are essential for the safety and efficiency of the
process. Many advanced control systems can create or update controls for
electro-hydraulic, analog-electronic, or relay and pneumatic based control
systems. For compressor drives, these systems include DCS interface and a
graphic operator interface, turbine and compressor sequencing, and surge and
capacity control. For generator drives, they include complete turbine control,
trending and data logging, and synchronization and protection.
Gas Turbine Uses
Variations of gas turbines have been used by Leonardo Da Vinci, Nikola
Tesla, and Sir Charles Parsons, and they have entered into common use in
many fields today. These turbines are used to create thrust for jet engines, for
mass power creation, or in ships, locomotives, helicopters, and tanks. A small
number of cars, buses, and motorcycles also use gas turbines.

Steam Power Plant
A steam cycle power plant is operated using the Rankine cycle. Water enters a boiler
where it is heated to create steam. The steam is then sent through a steam turbine that
rotates the shaft of a generator to create electricity. The steam exits the turbine into a
condenser, which converts the steam back into saturated water. The saturated water is
then pumped back into the boiler to repeat the process. It may seem strange that in the
Rankine cycle the steam is first cooled down so that it condenses into liquid water and
then is heated back up to create steam. This is done because liquid requires much less
energy to move than vapor. Because pumps are much more efficient than compressors,
the energy consumed by a pump to move the liquid water is negligible compared to the
overall amount of energy produced by the system.

Steam Power Plant
There are many extra components that are added to the basic
system which are used to improve the cycle’s efficiency. Some of
these components include: reheaters, moisture separators, and
feedwater heaters. With reheaters, the steam coming out of the
high pressure turbine is rerouted back to the boiler to be heated
again before being routed through subsequent lower pressure
turbines. This requires a minimal amount of additional heat while
providing extra power through the low pressure turbines. Water
droplets in the steam can cause damage to the turbine blades.
Moisture separators take the wet steam and, as it passes through,
filter out the water droplets so that dry steam comes out.
Feedwater heaters are essentially heat exchangers and it comes in
a couple main designs, open and closed. A portion of the steam is
taken after the high pressure turbine and routed to the feedwater
heater where it is used to heat the post-condenser water stream
before it is sent to the boiler. This reduces the amount of heat
needed from the boiler to produce the required temperature and
pressure of the steam going to the turbines.

Steam Power Plant
The efficiency of the simple steam cycle is generally lower than for other cycles such as
the combined cycle. This is mainly due to the fact that not all the heat can be harnessed or
completely used after the steam is sent through the steam turbines. This loss is dictated by
the laws of thermodynamics and limits the efficiency of the system. The efficiency is set, in
part, by the maximum temperature that the steam attains and the minimum temperature
that can be used to cool the steam in the condenser. The main source of the heat rejection
occurs in the condenser where the excess thermal energy is discharged to the environment
in the form of heat. In order to attain the required amount of power from the system, the
turbines and the steam temperatures and pressure must be properly designed in order to
work together properly and efficiently. However, there is still extra thermal energy in the
liquid-vapor mixture at the exhaust of the low pressure turbines that is not useable due to
the moisture content that would damage any more turbines without being reheated
significantly. Carnot’s theorem also shows that there is some inefficiency in the turbines
which is based off of the ratio of cold to hot temperatures in the cycle. This ratio is why
there are always inefficiencies in a system. This inefficiency in a steam turbine comes in
the form of the extra steam at the turbine exhaust.

Hydro Power Plant
Hydropower plants capture the energy of falling
water to generate electricity. A turbine converts the
kinetic energy of falling water into mechanical
energy. Then a generator converts the mechanical
energy from the turbine into electrical energy.

Parts of a Hydroelectric Plant
Most conventional hydroelectric plants include four major
components (see graphic below):
1. Dam. Raises the water level of the river to create falling
water. Also controls the flow of water. The reservoir that is
formed is, in effect, stored energy.
2. Turbine. The force of falling water pushing against the
turbine's blades causes the turbine to spin. A water turbine
is much like a windmill, except the energy is provided by
falling water instead of wind. The turbine converts the
kinetic energy of falling water into mechanical energy.
3. Generator. Connected to the turbine by shafts and possibly
gears so when the turbine spins it causes the generator to
spin also. Converts the mechanical energy from the turbine
into electric energy. Generators in hydropower plants work
just like the generators in other types of power plant.
4. Transmission lines. Conduct electricity from the
hydropower plant to homes and business.

How Much Electricity Can a Hydroelectric
Plant Make?
The amount of electricity a hydropower plant produces
depends on two factors: How Far the Water Falls. The farther the
water falls, the more power it has. Generally, the distance that the
water falls depends on the size of the dam. The higher the dam,
the farther the water falls and the more power it has. Scientists
would say that the power of falling water is "directly proportional"
to the distance it falls. In other words, water falling twice as far
has twice as much energy. Amount of Water Falling. More water
falling through the turbine will produce more power. The amount
of water available depends on the amount of water flowing down
the river. Bigger rivers have more flowing water and can produce
more energy. Power is also "directly proportional" to river flow. A
river with twice the amount of flowing water as another river can
produce twice as much energy.

Geothermal Power Plants
At a geothermal power plant, wells are drilled 1
or 2 miles deep into the Earth to pump steam or hot
water to the surface. You're most likely to find one of
these power plants in an area that has a lot of hot
springs, geysers, or volcanic activity, because these
are places where the Earth is particularly hot just
below the surface.

How does an Geothermal Power plants work?
1. Hot water is pumped
from deep
underground
through a well under
high pressure.
2. When the water
reaches the surface,
the pressure is
dropped, which
causes the water to
turn into steam.
3. The steam spins a
turbine, which is
connected to a
generator that
produces electricity.
4. The steam cools off in
a cooling tower and
condenses back to
water.
5. The cooled water is
pumped back into the
Earth to begin the
process again.

Nuclear Power plant
Nuclear plants split
atoms to heat water into
steam. The steam turns a
turbine to generate
electricity. It takes
sophisticated equipment
and a highly trained
workforce to make it
happen, but it’s that
simple.

How Is Nuclear Energy Used to Produce
Electricity?
In most power plants, you need to spin a turbine to generate electricity. Coal,
natural gas, oil and nuclear energy use their fuel to turn water into steam and use
that steam to turn the turbine.
• Nuclear plants are different because they do not burn anything to create steam.
Instead, they split uranium atoms in a process called fission. As a result, unlike
other energy sources, nuclear power plants do not release carbon or pollutants
like nitrogen and sulfur oxides into the air.
• Nuclear reactors are designed to sustain an ongoing chain reaction of fission;
they are filled with a specially designed, solid uranium fuel and surrounded by
water, which facilitates the process. When the reactor starts, uranium atoms will
split, releasing neutrons and heat. Those neutrons will hit other uranium atoms
causing them to split and continue the process, generating more neutrons and
more heat.
• This heat is used to create the steam that will spin a turbine, which powers a
generator to make electricity.

Solar Power Plant
Solar power plants use the sun's rays to produce electricity. Photovoltaic plants
and solar thermal systems are the most commonly used solar technologies today.
There are two types of solar power plants. They are differentiated depending on
how the energy from the sun is converted into electricity - either via photovoltaic or
"solar cells," or via solar thermal power plants.

Solar Power Plant
Photovoltaic plants
A photovoltaic cell, commonly called a solar cell or PV, is a technology
used to convert solar energy directly into electricity. A photovoltaic cell is
usually made from silicon alloys. Particles of solar energy, known as
photons, strike the surface of a photovoltaic cell between two
semiconductors.
These semiconductors exhibit a property known as the photoelectric
effect, which causes them to absorb the photons and release electrons. The
electrons are captured in the form of an electric current - in other words,
electricity.

Solar Power Plant
Solar thermal power plants
A solar thermal plant generates heat and electricity by concentrating the sun's energy. That in turn builds
steam that helps to feed a turbine and generator to produce electricity.
There are three types of solar thermal power plants:
1) Parabolic troughs
This is the most common type of solar thermal plant. A "solar field" usually contains many parallel rows of
solar parabolic trough collectors. They use parabola-shaped reflectors to focus the sun at 30 to 100 times its
normal intensity.
The method is used to heat a special type of fluid, which is then collected at a central location to generate high-
pressure, superheated steam.
2) Solar power tower
This system uses hundreds to thousands of flat sun-tracking mirrors called heliostats to reflect and
concentrate the sun's energy onto a central receiver tower. The energy can be concentrated as much as 1,500 times
that of the energy coming in from the sun.
A test solar power tower exists in Juelich in the western German state of North-Rhine Westphalia. It is spread over
18,000 square meters (194,000 square feet) and uses more than 2,000 sun-tracking mirrors to reflect and
concentrate the sun's energy onto a 60-meter-high (200-foot-high) central receiver tower.
The concentrated solar energy is used to heat the air in the tower to up to 700 degrees Celsius (1,300 degrees
Fahrenheit). The heat is captured in a boiler and is used to produce electricity with the help of a steam turbine.

Solar Power Plant
Solar thermal energy collectors work well even
in adverse weather conditions. They're used in the
Mojave Desert in California and have withstood
hailstorms and sandstorms.
3) Solar pond
This is a pool of saltwater which collects and
stores solar thermal energy. It uses so-called
salinity-gradient technology.
Basically, the bottom layer of the pond is extremely
hot - up to 85 degrees Celsius - and acts as a
transparent insulator, permitting sunlight to be
trapped from which heat may be withdrawn or
stored for later use.
This technology has been used in Israel since 1984
to produce electricity.

Wind Power Plant
Wind turbines work on a simple principle:
instead of using electricity to make wind—like a
fan—wind turbines use wind to make electricity.
Wind turns the propeller-like blades of a turbine
around a rotor, which spins a generator, which
creates electricity.

How does an Wind Power plant work?
Wind is a form of solar energy caused by a combination of
three concurrent events:
1. The sun unevenly heating the atmosphere.
2. Irregularities of the earth's surface
3. The rotation of the earth.
Wind flow patterns and speeds vary greatly across the
Earth and are modified by bodies of water, vegetation, and
differences in terrain. Humans use this wind flow, or
motion energy, for many purposes: sailing, flying a kite,
and even generating electricity.
The terms "wind energy" and "wind power" both
describe the process by which the wind is used to generate
mechanical power or electricity. This mechanical
power can be used for specific tasks (such as
grinding grain or pumping water) or a generator can
convert this mechanical power into electricity.
A wind turbine turns wind energy into electricity
using the aerodynamic force from the rotor blades, which
work like an airplane wing or helicopter rotor blade.
When wind flows across the blade, the air pressure on
one side of the blade decreases. The difference in air
pressure across the two sides of the blade creates both lift
and drag. The force of the lift is stronger than the drag
and this causes the rotor to spin. The rotor connects to the
generator, either directly (if it’s a direct drive turbine) or
through a shaft and a series of gears (a gearbox) that
speed up the rotation and allow for a physically smaller
generator. This translation of aerodynamic force to
rotation of a generator creates electricity.

Wastewater treatment plant
Wastewater treatment is a process to convert
wastewater – which is water no longer needed or
suitable for its most recent use – into an effluent
that can be either returned to the water cycle with
minimal environmental issues or reused. The latter
is called water reclamation and implies avoidance of
disposal by use of treated wastewater effluent for
various purposes.

Step by Step Wastewater Treatment Process
The following is a step by step process of how
wastewater is treated:
 Wastewater Collection This is the first step in
waste water treatment process. Collection systems
are put in place by municipal administration, home
owners as well as business owners to ensure that all
the wastewater is collected and directed to a central
point. This water is then directed to a treatment
plant using underground drainage systems or by
exhauster tracks owned and operated by business
people. The transportation of wastewater should
however be done under hygienic conditions. The
pipes or tracks should be leaking proof and the
people offering the exhausting services should wear
protective clothing.

 Odor Control At the treatment plant, odor control is very important. Wastewater contains a lot of dirty
substances that cause a foul smell over time. To ensure that the surrounding areas are free of the foul
smell, odor treatment processes are initiated at the treatment plant. All odor sources are contained and
treated using chemicals to neutralize the foul smell producing elements. It is the first wastewater
treatment plant process and it’s very important.
 Screening This is the next step in wastewater treatment process. Screening involves the removal of large
objects for example nappies, cotton buds, plastics, diapers, rags, sanitary items, nappies, face wipes,
broken bottles or bottle tops that in one way or another may damage the equipment. Failure to observe
this step, results in constant machine and equipment problems. Specially designed equipment is used to
get rid of grit that is usually washed down into the sewer lines by rainwater. The solid wastes removed
from the wastewater are then transported and disposed off in landfills.
 Primary Treatment This process involves the separation of macrobiotic solid matter from the
wastewater. Primary treatment is done by pouring the wastewater into big tanks for the solid matter to
settle at the surface of the tanks. The sludge, the solid waste that settles at the surface of the tanks, is
removed by large scrappers and is pushed to the center of the cylindrical tanks and later pumped out of
the tanks for further treatment. The remaining water is then pumped for secondary treatment.

 Secondary Treatment Also known as the activated sludge process, the secondary treatment stage involves
adding seed sludge to the wastewater to ensure that is broken down further. Air is first pumped into huge
aeration tanks which mix the wastewater with the seed sludge which is basically small amount of sludge,
which fuels the growth of bacteria that uses oxygen and the growth of other small microorganisms that
consume the remaining organic matter. This process leads to the production of large particles that settle down
at the bottom of the huge tanks. The wastewater passes through the large tanks for a period of 3-6 hours.
 Bio-solids handling The solid matter that settle out after the primary and secondary treatment stages are
directed to digesters. The digesters are heated at room temperature. The solid wastes are then treated for a
month where they undergo anaerobic digestion. During this process, methane gases are produced and there is
a formation of nutrient rich bio-solids which are recycled and dewatered into local firms. The methane gas
formed is usually used as a source of energy at the treatment plants. It can be used to produce electricity in
engines or to simply drive plant equipment. This gas can also be used in boilers to generate heat for digesters.
 Tertiary treatment This stage is similar to the one used by drinking water treatment plants which clean raw
water for drinking purposes. The tertiary treatment stage has the ability to remove up to 99 percent of the
impurities from the wastewater. This produces effluent water that is close to drinking water quality.
Unfortunately, this process tends to be a bit expensive as it requires special equipment, well trained and highly
skilled equipment operators, chemicals and a steady energy supply. All these are not readily available.

 Disinfection After the primary treatment stage and the secondary treatment process, there are
still some diseases causing organisms in the remaining treated wastewater. To eliminate them, the
wastewater must be disinfected for at least 20-25 minutes in tanks that contain a mixture of
chlorine and sodium hypochlorite. The disinfection process is an integral part of the treatment
process because it guards the health of the animals and the local people who use the water for
other purposes. The effluent (treated waste water) is later released into the environment through
the local water ways.
 Sludge Treatment The sludge that is produced and collected during the primary and secondary
treatment processes requires concentration and thickening to enable further processing. It is put
into thickening tanks that allow it to settle down and later separates from the water. This process
can take up to 24 hours. The remaining water is collected and sent back to the huge aeration
tanks for further treatment. The sludge is then treated and sent back into the environment and
can be used for agricultural use. Wastewater treatment has a number of benefits. For example,
wastewater treatment ensures that the environment is kept clean, there is no water pollution,
makes use of the most important natural resource; water, the treated water can be used for cooling
machines in factories and industries, prevents the outbreak of waterborne diseases and most
importantly, it ensures that there is adequate water for other purposes like irrigation.

List of Power Plants in the Philippines
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List of Power Plants in the Philippines
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REVIEW OF POWER PLANT

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