CHAPTER-1

1. INTRODUCTION-SOLAR POWER AIR COMPRESSOR

Solar Power Air compressor, as the name indicates, is a machine to compress the air and

to raise its pressure by taking its power from solar panels. The air compressor sucks air

from the atmosphere, compresses it and then delivers the same under a high pressure to a

place where the supply of compressed air is required. Years ago, it was common to have a

central power source that drove all the tools through a system of belts, wheels and drive

shafts. The power was routed around the work space by mechanical means. While the

belts and shafts may be gone, the use a mechanical system to move power around the

workspace still exists. It is based on the energy stored in air under pressure and the heart

of the system is the air compressor. Air compressors are used in a wide range of situations

- from corner gas stations to major manufacturing plants. Many more kinds of air

compressors are finding their way into homes, workshops, basements and garages.

Models are sized to handle every job - from inflating pool toys to powering tools such as

nail guns, sanders, drills, impact wrenches, staplers and spray guns. These are now

available through local home centers, tool dealers and mail-order catalogs. To run these

air compressors, a lot of electrical energy is required depending upon the output pressure

of the air. The non-renewable resources to produce electricity have become limited and

are near extinction, leading to high energy cost or energy crisis. In such situations,

renewable sources like solar power are very helpful and the application of this technology

to run air compressor is known as solar power air compressor. Already many non-

renewable energy dependent companies have started implementing solar power air

compressors for their industrial applications.

The solar power air compressor has a number of solar panels that consist of photovoltaic

cells. These cells create direct current electricity by the reaction of photons with Silicon

dioxide. This direct current is used to power a motor that works the compressor unit. It

can also be used to charge a battery bank that can be used as a backup when the sunlight

is considerably dim or at night.

1

CHAPTER-2

2. THE STUDY OF SOLAR POWER AIR COMPRESSOR

An Air Compressor is a device that converts power (usually from an electric motor, a

diesel engine or a gasoline engine) into kinetic energy by compressing and pressurizing

air, which, on command, can be released in quick bursts. There are numerous methods of

air compression, divided into either positive-displacement or negative-displacement

types.

2.1 TYPES OF AIR COMPRESSOR

According to the design and principle of operation -

Reciprocating compressor

Rotary screw compressor

Turbo compressor

2.1.1 POSITIVE DISPLACEMENT

Positive-displacement air compressors work by forcing air into a chamber whose volume

is decreased to compress the air. Piston-type air compressors use this principle by

pumping air into an air chamber through the use of the constant motion of pistons. They

use one-way valves to guide air into a chamber, where the air is compressed. Rotary

screw compressors also use positive-displacement compression by matching two helical

screws that, when turned, guide air into a chamber, whose volume is decreased as the

screws turn. Vane compressors use a slotted rotor with varied blade placement to guide

air into a chamber and compress the volume. A type of compressor that delivers a fixed

volume of air at high pressures. Common types of positive displacement compressors

include piston compressors and rotary screw compressors.

2.1.2 NEGATIVE DISPLACEMENT

Negative-displacement air compressors include centrifugal compressors. These use

centrifugal force generated by a spinning impeller to accelerate and then decelerate

captured air, which pressurizes it.

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2.2 COOLING

Due to adiabatic heating, air compressors require some method of disposing of

waste heat. Generally this is some form of air- or water-cooling, although some

(particularly rotary type) compressors may be cooled by oil (that is then in turn air- or

water-cooled) and the atmospheric changes also considered during cooling of

compressors.

2.3 APPLICATIONS

Fig.2.3.1 Portable Air Compressor

Portable air compressor for powering tools, such as jackhammers.

To supply high-pressure clean air to fill gas cylinders.

To supply moderate-pressure clean air to a submerged surface supplied diver.

To supply moderate-pressure clean air for driving some office and school

building pneumatic HVAC control system valves.

To supply a large amount of moderate-pressure air to power pneumatic tools, such

as jackhammers.

For filling tires.

To produce large volumes of moderate-pressure air for large-scale industrial

processes (such as oxidation for petroleum coking or cement plant bag house

purge systems).

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Most air compressors either are reciprocating piston type, rotary vane or rotary screw.

Centrifugal compressors are common in very large applications. There are two main types

of air compressor's pumps: oil-lubed and oil-less. The oil-less system has more technical

development, but is more expensive, louder and lasts for less time than oil-lubed pumps.

The oil-less system also delivers air of better quality.

Fig.2.3.2 Conventional Air Compressor

Fig.2.3.3 Solar Power Air Compressor

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2.4 MAIN COMPONENTS OF AIR COMPRESSOR

Fig.2.4 Main Components of Air Compressor

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2.4.1 SOLAR CELL

 A solar cell (also called a photovoltaic cell) is an electrical device that converts the

energy of light directly into electricity by the photovoltaic effect. It is a form

of photoelectric cell (in that its electrical characteristics—e.g. current, voltage, or

resistance - vary when light is incident upon it) which, when exposed to light, can

generate and support an electric current without being attached to any external voltage

source, but do require an external load for power consumption.

The term "photovoltaic" comes from the Greek word meaning "light", and from "volt",

the unit of electro-motive force, the volt, which in turn comes from the last name of

the Italian physicist Alessandro Volta, inventor of the battery (electrochemical cell). The

term "photo-voltaic" has been in use in English since 1849.

Photovoltaic is the field of technology and research related to the practical application of

photovoltaic cells in producing electricity from light, though it is often used specifically

to refer to the generation of electricity from sunlight. Cells can be described

as photovoltaic even when the light source is not necessarily sunlight (lamplight, artificial

light, etc.). In such cases the cell is sometimes used as a photo detector (for

example infrared detectors), detecting light or other electromagnetic radiation near the

visible range, or measuring light intensity.

The operation of a Photovoltaic (PV) Cell requires three basic attributes:

The absorption of light, generating either electron-hole pairs or exactions.

The separation of charge carriers of opposite types.

The separate extraction of those carriers to an external circuit.

In contrast, a solar thermal collector supplies heat by absorbing sunlight, for the purpose

of either direct heating or indirect electrical power generation. "Photo Electrolytic Cell"

(Photo Electrochemical Cell), on the other hand, refers either to a type of photovoltaic

cell (like that developed by Edmond Becquerel and modern dye-sensitized solar cells), or

to a device that splits water directly into hydrogen and oxygen using only solar

illumination.

6

The solar cell works in three steps:

Photons in sunlight hit the solar panel and are absorbed by semiconducting

materials, such as silicon.

Electrons (negatively charged) are excited from their current molecular/atomic

orbital. Once excited the electron can either dissipate the energy, and return to its

orbital or travel through the cell until it reaches an electrode. Current starts

flowing through the material to cancel the potential and this electricity is captured.

Due to the special composition of solar cells, the electrons are only allowed to

move in a single direction.

An array of solar cells converts solar energy into a usable amount of direct

current (DC) electricity.

2.4.1.1 PRACTICAL MATERIALS

Fig.2.4.1.1 Graph Representing Efficiency

Semiconductors with band gap between 1 and 1.5eV, or near-infrared light, have the

greatest potential to form an efficient single-junction cell.

Various materials display varying efficiencies and have varying costs. Materials for

efficient solar cells must have characteristics matched to the spectrum of available light.

Some cells are designed to efficiently convert wavelengths of solar light that reach the

Earth surface. However, some solar cells are optimized for light absorption beyond

Earth's atmosphere as well. Light absorbing materials can often be used in multiple

physical configurations to take advantage of different light absorption and charge

separation mechanisms.

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Industrial photovoltaic solar cells are made of mono-crystalline silicon, polycrystalline

silicon, amorphous silicon, cadmium telluride or copper indium selenite/sulfide, or GaAs-

based multi-junction material systems.

Many currently available solar cells are made from bulk materials that are cut

into wafers between 180 to 240 micrometers thick that are then processed like other

semiconductors.

Crystalline Silicon

Fig.2.4.1.2 Crystalline Silicon Battery

Basic structure of a silicon based solar cell and its working mechanism-

By far, the most prevalent bulk material for solar cells is crystalline silicon (abbreviated

as a group as c-Si), also known as "solar grade silicon". Bulk silicon is separated into

multiple categories according to crystallinity and crystal size in the

resulting ingot, ribbon, or wafer. These cells are entirely based around the concept of a p-

n junction.

Mono-crystalline Silicon (c-Si): often made using the Czochralski process.

Single-crystal wafer cells tend to be expensive, and because they are cut from

cylindrical ingots, do not completely cover a square solar cell module without a

substantial waste of refined silicon. Hence most c-Si panels have uncovered gaps

at the four corners of the cells.

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Polycrystalline Silicon or Multi-crystalline Silicon (poly-Si or mc-Si) is made

from cast square ingots — large blocks of molten silicon carefully cooled and

solidified. Poly-Si cells are less expensive to produce than single crystal silicon

cells, but are less efficient. United States Department of Energy data show that

there were a higher number of polycrystalline sales than mono-crystalline silicon

sales.

Ribbon Silicon is a type of polycrystalline silicon: it is formed by drawing flat

thin films from molten silicon and results in a polycrystalline structure. These

cells have lower efficiencies than poly-Si, but save on production costs due to a

great reduction in silicon waste, as this approach does not require

sawing from ingots.

Mono-like-multi Silicon: Developed in the 2000s and introduced commercially

around 2009, mono-like-multi, or cast-mono, uses existing polycrystalline casting

chambers with small "seeds" of mono material. The result is a bulk mono-like

material with poly around the outsides. When sawn apart for processing, the inner

sections are high-efficiency mono-like cells (but square instead of "clipped"),

while the outer edges are sold off as conventional poly. The result is line that

produces mono-like cells at poly-like prices.

Cadmium Telluride Solar Cell: A cadmium telluride solar cell uses a cadmium

telluride (CdTe) thin film, a semiconductor layer to absorb and convert sunlight

into electricity. One disadvantage of this technology, the only thin film material so

far to rival crystalline silicon in cost/watt, is that cadmium is a deadly poison.

Another issue is that tellurium (anion: "telluride") is a metal extremely rare in the

earth's crust. The cadmium present in the cells would be toxic if released.

However, release is impossible during normal operation of the cells and is

unlikely during fires in residential roofs. A square meter of CdTe contains

approximately the same amount of Cd as a single C cell nickel-cadmium battery,

in a more stable and less soluble form.

Copper Indium Gallium Selenite: Copper indium gallium selenite (CIGS) is

a direct band gap material. It has the highest efficiency (~20%) among thin film

materials (see CIGS solar cell). Traditional methods of fabrication involve

vacuum processes including co-evaporation and sputtering. Recent developments

at IBM and Nano solar attempt to lower the cost by using non-vacuum solution

processes.

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GaAs Thin Film Cells: The Dutch Radboud University Nijmegen set the record

for thin film solar cell efficiency using a single junction GaAs to 25.8% in August

2008 using only 4 µm thick GaAs layer which can be transferred from a wafer

base to glass or plastic film. Recently, this record has been increased to 28.8%.

The high efficiency obtained in GaAs thin film solar cells is attributed to the

extreme high quality GaAs epitaxial growth, surface passivation by the AlGaAs,

and the promotion of photon recycling by the thin film design.

Silicon Thin Films: Silicon thin-film cells are mainly deposited by chemical

vapor deposition (typically plasma-enhanced, PE-CVD) from silane gas

and hydrogen gas. Depending on the deposition parameters, this can yield.

Amorphous Silicon (a-Si or a-Si:H): An amorphous silicon (a-Si) solar cell is

made of amorphous or microcrystalline silicon and its basic electronic structure is

the p-i-n junction. a-Si is attractive as a solar cell material because it is abundant

and non-toxic (unlike its CdTe counterpart) and requires a low processing

temperature, enabling production of devices to occur on flexible and low-cost

substrates. As the amorphous structure has a higher absorption rate of light than

crystalline cells, the complete light spectrum can be absorbed with a very thin

layer of photo-electrically active material. A film only 1 micrometer thick can

absorb 90% of the usable solar energy. This reduced material requirement along

with current technologies being capable of large-area deposition of a-Si, the

scalability of this type of cell is high. However, because it is amorphous, it has

high inherent disorder and dangling bonds, making it a bad conductor for charge

carriers. These dangling bonds act as recombination centers that severely reduce

the carrier lifetime and pin the Fermi level so that doping the material to n- or p-

type is not possible. Amorphous Silicon also suffers from the Staebler-Wronski

effect, which results in the efficiency of devices utilizing amorphous silicon

dropping as the cell is exposed to light. The production of a-Si thin film solar cells

uses glass as a substrate and deposits a very thin layer of silicon by plasma-

enhanced chemical vapor deposition (PECVD). A-Si manufacturers are working

towards lower costs per watt and higher conversion efficiency with continuous

research and development on multi-junction solar cells for solar panels. Anwell

Technologies Limited recently announced its target for multi-substrate-multi-chamber

PECVD, to lower the cost to US $0.50 per watt. Amorphous silicon has a higher band

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gap (1.7 eV) than crystalline silicon (c-Si) (1.1 eV), which means it absorbs the visible

part of the solar spectrum more strongly than the infrared portion of the spectrum. As nc-

Si has about the same band gap as c-Si, the nc-Si and a-Si can advantageously be

combined in thin layers, creating a layered cell called a Tandem Cell. The top cell in a-Si

absorbs the visible light and leaves the infrared part of the spectrum for the bottom cell in

nc-Si.

2.4.1.2 MANUFACTURERS AND CERTIFICATION

National Renewable Energy Laboratory tests and validates solar technologies. There are

three reliable certifications of solar equipment: UL and IEEE (both U.S. standards) and

IEC. There are a huge array of Solar Cell Company’s worldwide, see List of photovoltaic

companies by country and rankings.

Solar cells are manufactured primarily in Japan, Germany, mainland China, Taiwan,

Malaysia and the United States, whereas Europe, China, the U.S., and Japan have

dominated (94% or more as of 2013) in installed systems for the last decade.[61] Numerous

other nations, however, have or are acquiring significant solar cell production capacity.

While technologies are constantly evolving toward higher efficiencies, the most effective

cells for low cost electrical production are not necessarily those with the highest

efficiency, but those with a balance between low-cost production and efficiency high

enough to minimize area-related balance of systems cost. Those companies with large

scale manufacturing technology for coating inexpensive substrates may, in fact,

ultimately be the lowest cost net electricity producers, even with cell efficiencies that are

lower than those of single-crystal technologies.

Global PV cell/module production increased by 10% in 2012 despite a 9% decline in

solar energy investments according to the annual 'PV Status Report" released by the

European Commission's Joint Research Centre." Since 2009 cell production has

quadrupled.

China

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Due mainly to heavy government investment, China has played by far the most important

role in changing the face of solar cell manufacturing in recent years. Chinese companies

produced solar cells/modules with a capacity of ~23 GW in 2013 (60% of global

production).

United States

Solar cell production in the U.S. has suffered due to the global financial crisis, but is now

on the rise, partly due to the precipitously falling price of quality silicon.

Fig.2.4.1.3 Solar Panel

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2.4.2 ELECTRIC MOTOR

An Electric Motor is an electric machine that converts electrical energy into

mechanical energy. In normal motoring mode, most electric motors operate through the

interaction between an electric motor's magnetic field and winding currents to generate

force within the motor. In certain applications, such as in the transportation industry

with traction motors, electric motors can operate in both motoring and generating or

braking modes to also produce electrical energy from mechanical energy.

Found in applications as diverse as industrial fans, blowers and pumps, machine tools,

household appliances, power tools, and disk drives, electric motors can be powered

by direct current (DC) sources, such as from batteries, motor vehicles or rectifiers, or

by alternating current (AC) sources, such as from the power grid, inverters or generators.

Small motors may be found in electric watches. General-purpose motors with highly

standardized dimensions and characteristics provide convenient mechanical power for

industrial use. The largest of electric motors are used for ship propulsion, pipeline

compression and pumped-storage applications with ratings reaching 100 megawatts.

Electric motors may be classified by electric power source type, internal construction,

application, type of motion output, and so on.

Devices such as magnetic solenoids and loudspeakers that convert electricity into motion

but do not generate usable mechanical power are respectively referred to as actuators and

transducers. Electric motors are used to produce linear force or torque (rotary).

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2.4.2.1 MOTOR CONSTRUCTION

Fig.2.4.2.1 Electric Motor Rotor (left) and Stator (right)

Rotor

In an electric motor the moving part is the rotor which turns the shaft to deliver the

mechanical power. The rotor usually has conductors laid into it which carry currents that

interact with the magnetic field of the stator to generate the forces that turn the shaft.

However, some rotors carry permanent magnets, and the stator holds the conductors.

Stator

The stationary part is the stator, usually has either windings or permanent magnets. The

stator is the stationary part of the motor’s electromagnetic circuit. The stator core is made

up of many thin metal sheets, called laminations. Laminations are used to reduce energy

loses that would result if a solid core were used.

Air Gap

In between the rotor and stator is the air gap. The air gap has important effects, and is

generally as small as possible, as a large gap has a strong negative effect on the

performance of an electric motor.

Windings

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Windings are wires that are laid in coils, usually wrapped around a laminated soft

iron magnetic core so as to form magnetic poles when energized with current.

Commutator

Fig.2.4.2.2 Small DC Motor with Commutator

A commutator is a mechanism used to switch the input of certain AC and DC machines

consisting of slip ring segments insulated from each other and from the electric motor's

shaft. The motor's armature current is supplied through the stationary brushes in contact

with the revolving commutator, which causes required current reversal and applies power

to the machine in an optimal manner as the rotor rotates from pole to pole. In absence of

such current reversal, the motor would brake to a stop. In light of significant advances in

the past few decades due to improved technologies in electronic controller, sensor less

control, induction motor, and permanent magnet motor fields, electromechanically

commutated motors are increasingly being displaced by externally commutated induction

and permanent magnet motors.

Motor Supply

A DC Motor is usually supplied through slip ring commutator as described above. AC

motors' commutation can be either slip ring commutator or externally commutated type,

can be fixed or variable speed control type, and can be synchronous or asynchronous

type. Universal Motors can run on either AC or DC.

Motor Control

Fixed-speed controlled AC motors are provided with direct-on-line or soft-start starters.

Variable speed controlled AC motors are provided with a range of different power

inverter, variable-frequency drive or electronic commutator technologies. The term

15

electronic commutator is usually associated with self-commutated brushless DC

motor and switched reluctance motor applications.

2.4.3 SOLAR BATTERY

Solar flooded tubular mono-block batteries are designed to offer reliable, consistent and

low maintenance power for renewable energy requirements. These batteries can be

subject to deep cycle applications and minimum maintenance in rural and power deficit

areas. The batteries have a capacity to withstand partial state of charge (PSOC) operation.

These mono-block batteries are available in 12 Volts from 20Ah to 200 Ah @ C10 at 27

deg.C to 1.80 vpc.

Manufacturers have also developed a 2-volt range of tubular batteries from 200Ah to

1000Ah for solar photovoltaic applications having a design life of ten years plus.

However, the life of the battery is dependent on the ambient temperatures and the number

of times it is cycled and the depth of discharge.

They have decided to develop these solar batteries keeping in mind the increased

awareness and public spending in the field of new and renewable energy for applications

in household lighting, street lighting and in rural and urban cellular telecom installations.

Increased government incentives and subsidies will, in the next couple years, lead to

increased spending by governmental agencies in the new and renewable energy.

The batteries are designed to give long life in cyclic operations and extremely long

intervals in topping up and even total freedom from maintenance. The batteries can be

adapted to use auto-fill systems and air agitation systems for faster charging and

avoidance of acid stratification in standby cells.

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2.4.3.1 ADVANTAGES

Similar to the tubular battery offerings, only difference being their capacity to withstand

partial state of discharge (PSOC) operation

Deep discharged batteries (Upto 80%).

Specially designed for rural and high power outage areas.

Consistent power output & high back-up.

Minimum maintenance.

Cost efficient.

Consumer Benefit.

Specifically designed to deliver reliable and consistent power for renewable

energy requirements and perform in rural & power deficit areas with minimum

maintenance.

Fig.2.4.3.1 Solar Battery

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2.4.4 POWER CONTROL UNIT (POWER INVERTER)

A Power Inverter or Inverter is an electronic device or circuitry that changes direct

current (DC) to alternating current (AC).

The input voltage, output voltage and frequency, and overall power handling, are

dependent on the design of the specific device or circuitry.

A power inverter can be entirely electronic or may be a combination of mechanical

effects (such as a rotary apparatus) and electronic circuitry. Static Inverters do not use

moving parts in the conversion process.

2.4.4.1 APPLICATIONS

Typical applications for power inverters include:

Portable consumer devices that allow the user to connect a battery, or set of batteries, to

the device to produce AC power to run various electrical items such as lights, televisions,

kitchen appliances, and power tools.

Use in power generation systems such as electric utility companies or solar generating

systems to convert DC power to AC power.

Use within any larger electronic system where engineering need exists for deriving an AC

source from a DC source.

Fig.2.4.4.1 Inverter

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2.4.5 PRESSURE VESSEL 

A Pressure Vessel is a closed container designed to hold gases or liquids at

a pressure substantially different from the ambient pressure.

The pressure differential is dangerous and fatal accidents have occurred in the history of

pressure vessel development and operation. Consequently, pressure vessel design,

manufacture, and operation are regulated by engineering authorities backed by legislation.

For these reasons, the definition of a pressure vessel varies from country to country, but

involves parameters such as maximum safe operating pressure and temperature.

2.4.5.1 USES

Fig.2.4.5.1 A Pressure Tank Connected to a Water Well and Domestic Hot Water System

19

Fig.2.4.5.2 A Few Pressure Tanks, here used to hold propane

2.4.5.2 DESIGN FEATURES

Leak before burst

Leak before burst describes a pressure vessel designed such that a crack in the vessel will

grow through the wall, allowing the contained fluid to escape and reducing the pressure,

prior to growing so large as to cause fracture at the operating pressure.

Many pressure vessel standards, including the ASME Boiler and Pressure Vessel Code

and the AIAA metallic pressure vessel standard, either require pressure vessel designs to

be leak before burst, or require pressure vessels to meet more stringent requirements

for fatigue and fracture if they are not shown to be leak before burst.

Safety valves

As the pressure vessel is designed to a pressure, there is typically a safety valve or relief

valve to ensure that this pressure is not exceeded in operation.

2.4.5.3 APPLICATIONS

Pressure vessels are used in a variety of applications in both industry and the private

sector. They appear in these sectors as industrial compressed air receivers and domestic

hot water storage tanks. Other examples of pressure vessels are diving

cylinders, recompression chambers, distillation towers, pressure reactors, autoclaves, and

many other vessels in mining operations, oil refineries and petrochemical plants, nuclear-

reactor vessels, submarine and space

ship habitats, pneumatic reservoirs, hydraulic reservoirs under pressure, rail vehicle

airbrake reservoirs, road vehicle airbrake reservoirs, and storage vessels for liquefied

gases such as ammonia, chlorine, propane, butane, and LPG.

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2.4.6 CHECK VALVE

A check valve, clack valve, non-return valve or one-way valve is a valve that normally

allows fluid (liquid or gas) to flow through it in only one direction.

Check valves are two-port valves, meaning they have two openings in the body, one for

fluid to enter and the other for fluid to leave. There are various types of check valves used

in a wide variety of applications. Check valves are often part of common household

items. Although they are available in a wide range of sizes and costs, check valves

generally are very small, simple, or inexpensive. Check valves work automatically and

most are not controlled by a person or any external control; accordingly, most do not have

any valve handle or stem. The bodies (external shells) of most check valves are made of

plastic or metal.

Fig.2.4.6 Check Valve

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2.4.7 PRESSURE GAUGE

Pressure Gauge, instrument for measuring the condition of a fluid (liquid or gas) that is

specified by the force that the fluid would exert, when at rest, on a unit area, such as

pounds per square inch or newton per square centimeter.

The reading on a gauge, which is the difference between two pressures, is known as

the gauge pressure. If the lower of the pressures is the pressure of the atmosphere, the

total, or absolute, pressure is the sum of the gauge and atmospheric pressures.

The simplest device for measuring static pressures up to about 90 pounds per square inch

(62 Newton per square cm) is a U-tube manometer (shown in the figure), in which one

column of a liquid in the tube is open to a region of high pressure and the other column to

a region of low pressure. The differential pressure is indicated by the difference in level

between the two columns of liquid, and it is calculated as the difference in level

multiplied by the density of the liquid.

These instruments employ mechanical linkages and so are primarily useful for measuring

static pressures or pressures that change slowly. For rapidly changing pressures, electrical

pressure transducers that convert pressure to an electrical signal are more suitable. These

include strain gauges; moving contact resistance elements; and inductance, reluctance,

capacitive, and piezoelectric devices. 

Fig.2.4.7 Pressure Gauge

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CHAPTER-3

3. HOW SOLAR CELLS WORK - COMPONENTS AND OPERATION

OF SOLAR CELLS

Since a solar cell is the only generator in a solar PV system, it is one of the

most important parts in a solar PV system. In the following paragraphs, a simple

introduction of a solar cell and how it operates is discussed, with reference links for better

understanding.

A Solar Cell: A solar cell is a solid-state electrical device (p-n junction) that converts the

energy of light directly into electricity (DC) using the photovoltaic effect. The process of

conversion first requires a material which absorbs the solar energy (photon), and then

raises an electron to a higher energy state, and then the flow of this high-energy electron

to an external circuit. Silicon is one such material that uses such process. A solar cell

structure is shown in figure 3.1 and a solar panel configuration in figure 3.2.

Fig.3.1 A Solar Cell Structure

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Fig.3.2 Solar Panel Configuration

PV Cells: PV cells are most commonly made of silicon, and come in two common

varieties, crystalline and thin-film cells, as detailed in Fig: 3.3.

Fig.3.3 Crystalline (Wafer-Based) and Thin-Film Photovoltaic Cell

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A p-n Junction: It is formed by joining p-type (high concentration of hole or deficiency

of electron) and n-type (high concentration of electron) semiconductor material. Due to

this joining, excess electrons from n-type try to diffuse with the holes of p-type whereas

excess hole from p-type try to diffuse with the electrons of n-type. Movement of electrons

to the p-type side exposes positive ion cores in the n-type side, while movement of holes

to the n-type side exposes negative ion cores in the p-type side, resulting in an electron

field at the junction and forming the depletion region. An animated visual explanation is

shown in this link: http://www.pveducation.org/pvcdrom/pn-junction/formation-pn-

junction.

A Light-Generated Current: Generation of current in a solar cell, known as the “light-

generated current,” involves two important processes. Absorption of incident photons to

create electron-hole pairs. Electron-hole pairs will generate in the solar cell provided that

the incident photon has an energy greater than that of the band gap. However, electrons

(in the p-type material), and holes (in the n-type material) are meta-stable and will only

exist, on average, for a length of time equal to the minority carrier lifetime before they

recombine. If the carrier recombines, then the light-generated electron-hole pair is lost

and no current or power can be generated.

Collection of these carriers by the p-n junction prevents this recombination by using a p-

n junction to spatially separate the electron and the hole. The carriers are separated by the

action of the electric field existing at the p-n junction. If the light-generated minority

carrier reaches the p-n junction, it is swept across the junction by the electric field at the

junction, where it is now a majority carrier. If the emitter and base of the solar cell are

connected together (i.e., if the solar cell is short-circuited), then the light-generated

carriers flow through the external circuit.

Photovoltaic Effect: The collection of light-generated carriers does not by itself give rise

to power generation. In order to generate power, a voltage must be generated as well as a

current. Voltage is generated in a solar cell by a process known as the “photovoltaic

effect.” The collection of light-generated carriers by the p-n junction causes a movement

of electrons to the n-type side and holes to the p-type side of the junction. Under short

circuit conditions, the carriers exit the device as light-generated current.

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3.1 SOLAR APPLICATIONS

For several years people have been wondering whether solar energy is really worth it, or

whether solar energy really capable of generating enough power compared to the

investment that is required. Also whether the electricity produced with solar power is can

really be put to any commercial use? Research and development teams around the world

have become determined to prove that solar energy is really a viable alternative energy

source. As the result many research institutes around the world have come up with

various options that suggest application of solar energy in almost all the basic appliances

in our daily life? In other words researchers around the world have been desperately

coming up with various ideas that suggest applications of solar energy sources.

Following are the application where solar energy can be used as an effective solution to

replace fossil fuel and prove that solar energy is not just a dream.

For thousands of years man has been harnessing the sun’s energy in various forms which

makes the sun’s energy more versatile and a favored form of alternative energy. First of

all the sun’s energy is abundantly available and every day. Therefore it truly is a

renewable energy source. Depending on the period of history, the use of solar energy has

varied. Even in the rural area, people make use of heat energy of the sun to dry clothes

and fish. It is also used for heating purposes with the help of solar water heater. Other

domestic applications also include distillation of water. Based on the types of industries

solar applications can be classified in to 3 categories, industrial, agricultural and power.

The industrial applications include solar water pumps that use solar energy to

power motors of the pumps to draw water. But this application where solar energy

is being used to power an airplane is a giant leap forward towards making solar

energy a viable choice of an alternative energy. However due to recent failures

due to inability of the solar energy to generate enough power rendered the crowd

of researchers to believe that the solar energy is a dream concept and is not

practical. However now this myth is finally being broken and new hopes have

risen to take solar energy to a next level.

Another application that is used on a much wider scale is the green houses. These

houses domes are covered with a transparent insulating material in order to isolate

the inner region of the dome from the temperature and pressure differences in the

region outside the dome. This keeps the inner region unaffected by bad weather,

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rain or storms thus allowing a perfect habitable condition for plants to thrive. The

recent studies show that if these houses are kept under controlled conditions a self

sustaining eco system can be formed within the dome, no matter where the

location of the dome is.

The PV panels used today are much cheaper and are able to absorb light more

efficiently. That is why home appliances such as water heater and cookers have

gone solar. The solar water heaters can use the solar heat energy to provide

boiling water for drinking or bathing and also for desalination purposes. For many

years solar energy is also used to keep the fish dry to prevent them from getting

spoiled.

An aircraft that could just keep flying indefinitely till it keeps getting solar energy.

Imagine a plane flying around the world without having to make a stop anywhere

to refuel. It’s a simple aircraft with motors propellers and wings except the fact

that the entire wing span has its upper portion covered with thin PV solar panels.

3.2 SOLAR ENERGY COMPARED TO OTHER ALTERNATIVE ENERGY

SOURCES

We have to switch to clean an energy source, which is for sure after realizing the

consequences of using the fossil fuel and destroying the environment. The big question is

how? Millions around the world depend on the vast energy reserves available deep down

the earth. The reserves are depleting and will dry out soon. On the other hand the demand

and the consumption rate are not going down. This is why we have to find out an energy

source which will not only be free of pollution and eco friendly but also be able to

produce enough energy to power our needs? So the question is whether there exist and

energy source that can meet our needs or not.

Wind is basically created with the temperature changes. We also know that the wind

blows from a high pressure area to a low pressure area. These changes in the temperature

and pressure occur due to the difference in the amounts of heat energy received by

different areas from the sun depending on the earth’s rotation. This energy in the form of

wind can be converted into electrical or chemical energy, stored in the batteries. The

devices used to tap this wind energy are windmills. As the wind blows the rotational

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energy of turbines is converted into electrical energy by generators. The process is clean,

eco friendly and also renewable.

One wind mill can produce enough energy to power a house. However the electrical

energy that is produced from the turbines is not enough compared to the energy produced

from the fossil fuels. The disadvantage is that it is costly and not completely renewable;

therefore a better way needs to be discovered to produce energy completely clean and eco

friendly. As the wind does not blow at a constant speed and there is no certainty about the

wind direction and therefore the output is not efficient as it should be. Also, the wind

mills subjected to a severe damage when struck by heavy rains and lightning storms can

be subjected to heavy damage. The second is the biomass.

Biomass is a true renewable energy of energy. This is because the substance used to

produce energy is the excretal waste and remains of plant and animal; also human waste.

Basically any organic material can produce bio energy. This therefore includes

agricultural wastes, organic wastes, waste paper and waste from the food processing

industries. Since this type of waste keeps getting produced everyday and in tons, there is

no chance that the biomass energy such as bio fuel can get exhausted. The cons are

similar to the wind power, very expensive therefore not enough energy output. Apart

from these constraints, a bi product is created nitrogen oxide which is not good for the

atmosphere if produced in large amounts.

Next is the solar energy, out of all the three energy sources this one is the most diversified

form of renewable energy. Sun’s heat energy can be used for various purposes which

make it versatile. Through technological advancement, we have the capability to tap solar

energy and produce energy and then store it. We also have developed devices that can

harness the sun’s heat energy for different purposes such as distilling water, boiling water

for bathing or drinking etc. the cons is that the sunlight only remains for sometime during

the day and therefore our solar panels should be efficient enough to absorb enough energy

that can take us through the day. But as mentioned above efficient panels have been built

and there is hope that we will be able to create solar panels powerful enough to absorb

more energy and become self sufficient. Therefore solar energy seems to be the true

alternative energy source we can turn to.

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3.3 SCOPE OF SOLAR ENERGY

History suggests that the technological discoveries have led to a creation of vast and

progressing industries within themselves. For example 100 years ago when Wright

brothers made the first airplane it opened a totally new possibility of flying which made

the investors to notice and encourage the market and then forty years later the air flying

became a fully fledged industries and it became a serious business. In the same way when

the first computer was invented during the second world war, the idea of a machine that

could calculate at a lightning speed was came true, this encouraged the further

development around the world and this led to the creation of a computer industry. The

point is that any major breakthrough in the technology and commercial industry as well,

starts with a birth of small idea. The idea may not be as realistic to become a reality but

given some time to it can turn into something much bigger than ever imagined. And this I

believe is the scope of solar energy.

The solar energy is the most vast and abundantly available form of energy. Therefore it is

possible to imagine our cars powered by sunlight and our refrigerators running on solar

energy. Seeing the current efforts to improve solar energy go in vain, it might seem that

the future of car running on sunlight may be too far away from reality. However the

technological advancement and man’s urge to become fossil fuel independent will

continue man to find the solution of how to make energy coming from solar energy more

effective. Plus the scope of solar energy has no limits.

For years man has realized importance of sunlight for his survival and its potential as an

energy source. Also the man has been harnessing this energy for various

domestic purposes depending on the era in time. In fact it is the solar energy that has

given the rise to various other renewable energy sources such as biofuels, organic fuels,

wind energy and geothermal energy. As the result you may not tap solar energy in its raw

form, the very fact that the sun and the solar energy can affect different energy sources

and the natural environment. There are different ways from which we can generate energy

which has indirectly come from the sun. The biomass processing plant, the geo thermal

power plants are the some examples.

Since the techniques used to draw solar energy in the different forms is possible we are

able to use the solar energy in various numbers of industries including the industrial,

agricultural and power industries. The direct forms of applications include the

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desalination of sea water in order to generate pure drinkable water, the heating of water

for cooking purposes; solar cooker is one such application, solar energy tapped with solar

energy photovoltaic cells can be used to power fridge and air conditioners. The industrial

applications include production of steam, construction of green house and water pumping.

The power applications include installing hydro-thermal plants; it also contributes in

ocean thermal energy conversion.

The scope of solar energy is quite wide and seeing so many applications of solar energy

in the various above mentioned solar applications, become a minor part of our life. In

order to have solar energy contribute more in our life. Larger and bigger projects have to

be taken to increase the solar energy output. Also it is very likely that more emphasis will

be given to alternative sources of energy in order to tackle current global problems. Solar

energy has it is very unlikely that the solar energy will be forgotten as a dream that never

became a reality.

3.4 SOLAR ENERGY VS FOSSIL FUEL

Is solar energy really an alternate source to our energy need?

With growing concerns about the damage caused by the environment due to burning

fossil fuels, and due to ever increasing oil demand in spite of such hike in the prices per

barrel there have been some serious attempts to find out an energy source which can serve

as an alternate energy for fossil fuel. This is the reason why many researchers have turned

their attention to the solar energy. However the initial attempts to make electricity and

generate power out of sun light have achieved a little or no success. However with the

further advancement in the semiconductor technology and technology to make cheap

solar cells has made it possible for us to take this option seriously. And it is possible to

have a part of our energy come from a clean energy source such as solar energy. This will

reduce the dependence on fossil fuels up to some extent.

Well at least someday we will have to give this a thought because we are running out of

options at a very quickly and unnoticeably. The annual oil production rate in the world is

not going remain what it is. Plus the consumption is not going to go down. With the

population reaching about 7 billion and the number of cars on the road going twice within

the next three decades, some or the other day we have to work this out. So why not do it

now instead of then when we have no options left the world starts to panic.

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Let us discuss the practical calculation that will lead us to a conclusion if the above facts

are actually true or not. First of all let us discuss the amount of electricity that a house of

three needs a day. For this we need to identify things in our house that needs electricity

every day, and they can be classified into three categories. First we need to include the

electronic appliances such as laptop, cell phones laptop, PCs. Find out how much each of

these devices draw electricity, which comes out to be a total of 900Watts. The second

category of appliances includes the household appliances such as washing machines,

refrigerators, LED lamps, outdoor lights and any other lights you used for decoration.

These appliances thought necessary draw a significant amount of electricity and has to be

reduced. Therefore we have considered taking some necessary measure to reduce the

utilization of these appliances and then calculate the energy consumption of such

appliances. Therefore it comes out to be around 10KW. The third category involves the

necessary energy usage, the ones you can’t get rid of, they are the lights and the fans and

the air conditioners however you could choose to replace tube lights with CFLs or LEDs

and use an air conditioner that is eco friendly and takes up less power.

So how much energy can a solar panel generate? It has been calculated that a 60 X 26 X

1.8 (length X breadth X depth) can generate merely 123 watts on a good sunny day if kept

under direct sunlight for about 5-6 hours. So for a house using 12KW of power, how can

a solar panel generating 123 Watts do any good? The thing is a single panel when

installed gives you 123W but 10 panels when installed can give you about 1Kw which is

almost 10% of your household energy requirement. Plus this is the poly-crystal solar

panel of an average quality. There have been ways to use different semi conductor other

than silicon and make solar panels more efficient. So the only two options that remain in

our hands is to reduce our energy requirement, and start using renewable energy as a

serious alternate source.

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CHAPTER-4

4. APPLICATION OF SOLAR POWER AIR COMPRESSOR

4.1 SPRAY PAINTING

Fig.4.1 Paint Gun

Spray Painting is a painting technique where a device sprays a coating (paint, ink,

varnish, etc.) through the air onto a surface. The most common types employ compressed

gas—usually air—to atomize and direct the paint particles. Spray guns evolved

from airbrushes, and the two are usually distinguished by their size and the size of the

spray pattern they produce. Airbrushes are hand-held and used instead of a brush for

detailed work such as photo retouching, painting nails or fine art. Air gun spraying uses

equipment that is generally larger. It is typically used for covering large surfaces with an

even coating of liquid. Spray guns can be either automated or hand-held and have

interchangeable heads to allow for different spray patterns. Single color aerosol paint cans

are portable and easy to store.

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4.2 TYPES

Air Gun Spraying

This process occurs when paint is applied to an object through the use of an air

pressurized spray gun. The air gun has a nozzle, paint basin, and air compressor. When

the trigger is pressed the paint mixes with the compressed air stream and is released in a

fine spray.

Fig.4.2 Types of Nozzles and Sprays

Due to a wide range of nozzle shapes and sizes, the consistency of the paint can be varied.

The shape of the work piece and the desired paint consistency and pattern are important

factors when choosing a nozzle. The three most common nozzles are the full cone, hollow

cone, and flat stream.[3] There are two types of air-gun spraying processes. In a manual

operation method the air-gun sprayer is held by a skilled operator, about 6 to 10 inches

(15–25 cm) from the object, and moved back and forth over the surface, each stroke

overlapping the previous to ensure a continuous coat.[4] In an automatic process the gun

head is attached to a mounting block and delivers the stream of paint from that position.

The object being painted is usually placed on rollers or a turntable to ensure overall equal

coverage of all sides.

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4.3 ADVANTAGES OF SOLAR POWER AIR COMPRESSOR

• Economical -The rising cost of electricity has led people to search for ways to cut costs

related to powering their homes and appliances or running their RVs. While the up-front

cost of installing solar panels can seem expensive, their 25+ year lifespan with almost no

maintenance costs, coupled with the free energy provided by the sun, makes them a cost-

effective way to offset your utility bill. In addition, government rebates and tax breaks

can help with the cost of installing solar panels.

• Clean - Power from the sun is clean and infinitely renewable. Solar power emits no

fumes and creates no greenhouse gases or carbon emissions. It is one of the most

environmentally friendly energy solutions available. In addition, solar power is silent,

creating no noise pollution.

• Low Maintenance - Solar panels are self-sustaining. They have an expected life span of

25+ years and require almost no maintenance.

4.4 DISADVANTAGES OF SOLAR POWER AIR COMPRESSOR

The main disadvantage of solar power air compressor is the initial cost. Most types of

solar cell require large areas of land to achieve average efficiency. Air pollution and

weather can also have a large effect on the efficiency of the cells. The silicon used is also

very expensive and the problem of nocturnal down times means solar cells can only ever

generate during the daytime. Solar energy is currently thought to cost about twice as

much as traditional sources (coal, oil etc). Obviously, as fossil fuel reserves become

depleted, their cost will rise until a point is reached where solar cells become an

economically viable source of energy. When this occurs, massive investment will be able

to further increase their efficiency and lower their cost.

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CHAPTER-5

5. MARKET SURVEY

Market Survey is defined as the study of the spending characteristics and purchasing

power of the consumer who are within your businesses geographic area of operation; a

research method for defining the market parameters of a business.

Market Survey are an important part of market research that measure the feelings and

preferences of customers in a given market. Varying greatly in size, design and purpose,

market surveys are one of the main pieces of data that companies and organization use in

determining what products and services to offer and to market them.

We have prepared our Market Survey forms to find out the feasibility of our project.

Following shows the result of our Market Survey:

SOLAR POWER AIR COMPRESSOR-MARKET SURVEY

YESNOMAY BENO IDEA

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CHAPTER-6

6. GANTT CHART

A Gantt chart is a type of bar chart, developed by Henry Gantt in the 1910s, that

illustrates a project schedule. Gantt charts illustrate the start and finish dates of the

terminal elements and summary elements of a project. Terminal elements and summary

elements comprise the work breakdown structure of the project. Modern Gantt charts also

show the dependency (i.e. precedence network) relationships between activities. Gantt

charts can be used to show current schedule status using percent-complete shadings and a

vertical "TODAY" line as shown here.

Although now regarded as a common charting technique, Gantt charts were considered

extremely revolutionary when first introduced. This chart is also used in information

technology to represent data that has been collected.

Gantt charts can be used for scheduling generic resources, so as well as their use in

project management, they can also be used in scheduling production

processes and employee rostering. In the latter context, they may also be known

as timebar schedules.

There are many computer applications supporting the use of Gantt charts for employee

scheduling, for example, Ganttic.

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CHAPTER-7

7. PROJECT IMAGES

FIG: 7.1

FIG: 7.2

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FIG: 7.3

FIG: 7.4

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FIG: 7.5

FIG: 7.6

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