4Contents - Google Docs

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CHAPTER-1

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CHAPTER-1

INTRODUCTION

This project reveals the comfort conditions achieved by the device for the human body. In

summer (hot) and humid conditions feel uncomfortable because of hot weather and heavy humidity.

So it is necessary to maintain thermal comfort conditions. Thermal comfort is determined by the

room’s temperature, humidity and air speed. Radiant heat (hot surfaces) or radiant heat loss (cold

surfaces) are also important factors for thermal comfort. Relative humidity (RH) is a measure of the

moisture in the air, compared to the potential saturation level. Warmer air can hold more moisture.

When you approach 100% humidity, the air moisture condenses – this is called the dew point. The

temperature in a building is based on the outside temperature and sun loading plus whatever heating

or cooling is added by the HVAC or other heating and cooling sources. Room occupants also add

heat to the room since the normal body temperature is much higher than the room temperature. Need

of such a source which is abundantly available in nature, which does not impose any bad effects on

earth. There is only one thing which can come up with these all problems is solar energy.

The use of solar energy for cooling can be either to provide refrigeration for food

preservation or to provide comfort cooling. There is less experience with solar cooling than solar

heating. Several solar heated buildings have been designed, built, operated for extended periods but

only a few short time experiments have been reported on solar cooling. However, research work is

expected to close the gap between the two within few years.

Solar air conditioning systems have used two basic approaches in an attempt to capture the sun’s

energy for cooling thermal and photovoltaic. The photovoltaic systems use photovoltaic panels to

convert solar radiation directly into DC electricity. Photovoltaic systems have two major

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advantageous attributes. First, they can use conventional electrically driven air-conditioning

equipment, which is widely available and inexpensive. Second, they can use the utility grid for

backup power during dark or cloudy periods.

Unfortunately other attributes: the high cost of manufacturing, the low conversion efficiencies, and

the need for a continual stream of photons to produce power, create three major disadvantages. First

electricity from solar cells is very expensive because of the high cost of the solar panels. Second the

space needed for powering the air conditioning units is large. And third the panels provide no energy

storage, which creates a need for use of grid-based electricity at night and on cloudy days. In fact,

the peak output from the solar panels occurs around solar noon, while peak air-conditioning loads

occurs several hours later, resulting in a significant mismatch between supply of needed power and

demand. This mismatch greatly reduces the value of the system in reducing peak power demand to

the utility. Recently deregulated markets are demonstrating that these demands are much more

expensive to meet than had been previously apparent.

For off-grid locations, the only viable energy storage system to match the provision of power to

times when demand is high (later in afternoon and at night) is batteries. Batteries have a high first

cost, require periodic replacement, and normally use toxic and/or corrosive materials. These

problems have prevented the use of photovoltaic systems in other than a few high-cost

demonstration systems.

Thermally driven systems are another approach; they use heat from the sun to drive an air

conditioner. Typical approaches from the past used a high-temperature flat-plate collector to supply

heat to an absorption system. Systems with concentrating collectors and steam turbines have also

been proposed. Natural gas or other fuel is used for backup heat.

While thermal systems have the advantage of eliminating the need for expensive photovoltaic

panels, the existing systems have attributes that produce major disadvantages. As used in the past,

thermal systems are based on single-effect absorption chillers or other cooling systems that are

designed to use natural gas, steam or other high-temperature heat source. They require a very high

collector temperature to drive the cooling system. The high collector temperature and relatively poor

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efficiency, greatly increases collector size and cost. In addition, there is no economically viable way

of storing solar energy with this approach. The result of these problems is that thermal systems have

been very expensive and have relied primarily on natural gas or other fuel for their thermal energy.

For this reason they have seen very little use.

1.1 Present Problem:

The producing of electricity is ultimately responsible for hot and humid conditions i.e.

global warming. As in below shown chart it is clear that major quantity of electricity is produced by

coal (fossil fuel).

Fossil fuels also contain radioactive materials, mainly uranium and thorium, which are released into

the atmosphere, which contribute to smog and acid rain, emit carbon dioxide, which may contribute

to climate change. Longer power cut durations in villages and high cost of cooling products.

Figure 1.1: Production of electricity from different source

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1.2 Proposed Solution:

Need of such a source which is abundantly available in nature, which does not impose any

bad effects on earth. There is only one thing which can come up with these all problems is solar

energy.

Objective the Project:

● To make aware of non-conventional energy sources to reduce environmental pollutions.

● To provide solution for power cut problems in villages

● To replace existing costlier and high energy consumption

CHAPTER-2

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CHAPTER-2

LITERATURE REVIEW

Kant and Mullick (2003) have studied on thermal comfort in aroom with exposed roof using

evaporative cooling system. Hourly values of temperature and humidity are computed and compared

with the values that are obtained during unexposed condition. The levels of thermal sensation, which

could be obtained with a direct evaporative cooler, are computed.

El-Dessouky et al (2000) have developed For better human comfort, cooling of living or

work environment is vital in tropical climates. Researches carried out till date in evaporative air

cooling process focus mainly on reducing the dry bulb temperature of theincoming air. Theoretical

efficiency of 100% can be realized when dry bulb temperature of the room is equal to wet bulb

temperature of the outside ambient air; cooling efficiency is defined as the ratio between drop in dry

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bulb temperature across the cooler and the difference between inlet DBT and inlet WBT. Many

researchers have worked on improving cooling efficiency to the maximum possible extent.

Gomez et al (2005) have developed a ceramic solar cooling system which acts as a semi-indirect

cooler. The water cooled in a cooling tower is passed through the annulus passage of the ceramic

tube. The out side air is passed through the central region. Chilled water evaporates by seeping

through pores.

Jain (2007) has developed and tested a two-stage evaporative cooler. Such a cooler could provide

necessary comfort even though outside humidity is higher. The two-stage cooler is found to provide

20 % better cooling when compared to single stage cooler.

CHAPTER-3

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CHAPTER-3

SOLAR ENERGY

Solar energy is radiant light and heat from the Sun harnessed using a range of

ever-evolving technologies such as solar heating, photovoltaics, solar thermal energy, solar

architecture and artificial photosynthesis.It is an important source of renewable energy and its

technologies are broadly characterized as either passive solar or active solar depending on the

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way they capture and distribute solar energy or convert it into solar power. Active solar

techniques include the use of photovoltaic systems, concentrated solar power and solar water

heating to harness the energy. Passive solar techniques include orienting a building to the

Sun, selecting materials with favorable thermal mass or light dispersing properties, and

designing spaces that naturally circulate air.

The large magnitude of solar energy available makes it a highly appealing source of

electricity. The United Nations Development Programme in its 2000 World Energy

Assessment found that the annual potential of solar energy was 1,575–49,837 exajoules (EJ).

This is several times larger than the total world energy consumption, which was 559.8 EJ in

2012.In 2011, the International Energy Agency said that "the development of affordable,

inexhaustible and clean solar energy technologies will have huge longer-term benefits. It will

increase countries’ energy security through reliance on an indigenous, inexhaustible and

mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs

of mitigating global warming, and keep fossil fuel prices lower than otherwise. These

advantages are global. Hence the additional costs of the incentives for early deployment

should be considered learning investments; they must be wisely spent and need to be widely

shared".

The Earth receives 174,000 terawatts (TW) of incoming solar radiation (insolation) at

the upper atmosphere. Approximately 30% is reflected back to space while the rest is

absorbed by clouds, oceans and land masses. The spectrum of solar light at the Earth's

surface is mostly spread across the visible and near-infrared ranges with a small part in the

near-ultraviolet. Most people around the world live in areas with isolation levels of 150 to

300 watts per square meter or 3.5 to 7.0 kWh/m 2 per day.

Solar radiation is absorbed by the Earth's land surface, oceans – which cover about

71% of the globe – and atmosphere. Warm air containing evaporated water from the oceans rises, causing atmospheric circulation or convection. When the air reaches a high altitude,

where the temperature is low, water vapor condenses into clouds, which rain onto the Earth's

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surface, completing the water cycle. The latent heat of water condensation amplifies

convection, producing atmospheric phenomena such as wind, cyclones and anti-cyclones.

Sunlight absorbed by the oceans and land masses keeps the surface at an average temperature

of 14 °C. By photosynthesis green plants convert solar energy into chemically stored energy,

which produces food, wood and the biomass from which fossil fuels are derived.

The total solar energy absorbed by Earth's atmosphere, oceans and land masses is

approximately 3,850,000 exajoules (EJ) per year. In 2002, this was more energy in one hour

than the world used in one year. Photosynthesis captures approximately 3,000 EJ per year in

biomass. The amount of solar energy reaching the surface of the planet is so vast that in one

year it is about twice as much as will ever be obtained from all of the Earth's non-renewable

resources of coal, oil, natural gas, and mined uranium combined the potential solar energy

that could be used by humans differs from the amount of solar energy present near the

surface of the planet because factors such as geography, time variation, cloud cover, and the

land available to humans limits the amount of solar energy that we can acquire.

Geography affects solar energy potential because areas that are closer to the equator

have a greater amount of solar radiation. However, the use of photo voltaics that can follow

the position of the sun can significantly increase the solar energy potential in areas that are

farther from the equator. Time variation affects the potential of solar energy because during

the nighttime there is little solar radiation on the surface of the Earth for solar panels to

absorb. This limits the amount of energy that solar panels can absorb in one day. Cloud cover

can affect the potential of solar panels because clouds block incoming light from the sun and

reduce the light available for solar cells.In addition, land availability has a large effect on the

available solar energy because solar panels can only be set up on land that is unowned and

suitable for solar panels. Roofs have been found to be a suitable place for solar cells, as many

people have discovered that they can collect energy directly from their homes this way. Other

areas that are suitable for solar cells are lands that are unowned by businesses where solar

plants can be established..

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Active solar techniques use photo voltaic, concentrated solar power, solar

thermal collectors, pumps, and fans to convert sunlight into useful outputs. Passive solar

techniques include selecting materials with favorable thermal properties, designing spaces

that naturally circulate air, and referencing the position of a building to the Sun. Active solar

technologies increase the supply of energy and are considered supply side technologies,

while passive solar technologies reduce the need for alternate resources and are generally

considered demand side technologies.

FIGURE: 3.1 how to get solar energy to battery and load

Solar technologies are broadly characterized as either passive or active depending on the way they

capture, convert and distribute sunlight and enable solar energy to be harnessed at different levels

around the world, mostly depending on distance from the equator. Although solar energy refers

primarily to the use of solar radiation for practical ends, all renewable energies, other than

geothermal and tidal, derive their energy from the Sun in a direct or indirect way

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Figure: 3.2 solar energy utilization

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CHAPTER-4

CHAPTER-4

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WORKING OF THE PROJECT

Working Methodology:

This project mainly consists of two sections:

4.1 Solar Energy Conversion:

Solar energy conversion is done by using battery, inverter and charge controller. As sun light

falls on solar panel, which converts into electrical energy by photoelectric effect. This electrical

energy stored in battery in the form of chemical energy. Charge controller is employed in between

solar panel and battery which prevents overcharging Figure 2: Solar energy conversion process and

may protect against overvoltage, which can reduce battery performance or lifespan, and may pose a safety risk.

The stored energy directly can use for DC loads or else need to be converted AC (alternate

current) bythe help of inverter. Figure 2: Solar energy conversion process

4.2 Cool air generation by centrifugal fan:

The converted energy is used to run the centrifugal fan. This fan covered with cooling pads,

through which water is passed at a specific rate. As the fan sucks the hot air through cooling pads,

heat transfer occur between air and water thus generated cool air enters into the room. Figure 3:

Process of cool air generation by centrifugal fan.

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Fig 4.1 Air cooler

4.3 Working Model of the Project:

Solar powered air cooler. This concept is driven by solar energy. Components involved in

this concept are solar panel, battery, charge controller, battery, inverter, blower, ceramic slabs and

cooling pads. Solar panel is employed to convert sun light into electrical energy by means of

photovoltaic effect. The generated electrical energy is supplied to the battery for storage purpose

through charge controller which prevents from power fluctuations. As AC blower is used for cooler,

so need to convert DC load from the battery to AC load by the help of inverter. Inverter converts DC

load to AC. Load, now AC power can be supplied to the blower. This blower is surrounded by

cooling pads through which continuous water supply is provided. When the blower is switched on,

blower sucks atmospheric air into the cabin through the cooling pads, mean time heat transfer occur

Between water and air, so the cool air enters into the room thus providing required thermal comfort

conditions.

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Fig no: 4.2 working of the solar powered air cooler

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CHAPTER-5

CHAPTER-5

COMPONENTS USED

5.1 Solar panel

Solar chargers convert light energy into DC current. They are generally portable, but can also be fixed mount. Fixed mount solar chargers are also known as solar panels. Solar panels are often

connected to the electrical grid, where as portable solar chargers as used off-the-grid (i.e. cars, boats,

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or RVs).Although portable solar chargers obtain energy from the sun only, they still can (depending

on the technology) be used in low light (i.e. cloudy) applications.

Portable solar charger are typically used for trickle charging, although some solar charger

(depending on the wattage), can completely recharge batteries.Solar panels (arrays of photovoltaic

cells) make use of renewable energy from the sun, and are a clean and environmentally sound means

of collecting solar energy.

Fig no: 5.1 Solar panel

5.2 Crystalline Silicon Solar Panels

The creation of solar panels typically involves cutting crystalline silicon into tiny disks less

than a centimeter thick. These thin, wafer-like disks are then carefully polished and treated to repair

and gloss any damage from the slicing process. After polishing, dopants (materials added to alter an

electrical charge in a semiconductor or photovoltaic solar cell) and metal conductors are spread

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across each disk. The conductors are aligned in a thin, grid-like matrix on the top of the solar panel,

and are spread in a flat, thin sheet on the side facing the earth.

To protect the solar panels after processing, a thin layer of cover glass is then bonded to the top of

the photovoltaic cell. After the bonding of protective glass, the nearly-finished panel is attached to a

substrate by expensive, thermally conductive cement. The thermally conductive property of the

cement keep the solar panel from becoming overheated; any leftover energy that the solar panel is

unable to convert to electricity would otherwise overheat the unit and reduce the efficiency of the

solar cells. Despite these protective measures against the tendency of solar panels to overheat, it is

vital that when installing a solar panel, additional steps should be taken to ensure the solar panel is

kept cool. Elevating the solar panel above ground, to let the airflow underneath, will cool the device.

5.3Amorphous Silicon Solar Panels

Amorphous silicon solar panels are a powerful that differ in output, structure and

manufacture than traditional photovoltaic’s which use crystalline silicon. Amorphous silicon solar

cells, or A-si cells, are developed in a continuous roll-to-roll process by vapor-depositing silicon

alloys in multiple layers, with each extremely thin layer specializing in the absorption of different

parts of the solar spectrum. The result is record-breaking efficiency and reduced materials cost (A-si

solar cells are typically thinner than their crystalline counterparts).

5.4 How does the solar panel works

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The solar cells on the calculators and satellites are also called photovoltaic (PV) cells, which

as the name implies (photo meaning "light" and voltaic meaning "electricity"), convert sunlight

directly into electricity. A module is a group of cells connected electrically and packaged into a

frame (more commonly known as a solar panel), which can then be grouped into larger solar arrays.

Photovoltaic cells are made of special materials called semiconductors such as silicon, which

is currently used most commonly. Basically, when light strikes the cell, a certain portion of it is

absorbed within the semiconductor material. This means that the energy of the absorbed light is

transferred to the semiconductor. The energy knocks electrons loose, allowing them to flow freely.

PV cells also all have one or more electric field that acts to force electrons freed by light absorption

to flow in a certain direction. This flow of electrons is a current and by placing metal contacts on the

top and bottom of the PV cell, the current can be drawn off for external use such as to power a

calculator. This current, together with the cell's voltage (which is a result of its built-in electric field

or fields), defines the power (or wattage) that the solar cell can produce.

5.5Battery:

An electrical battery is one or more electrochemical cells that convert stored chemical

energy into electrical energy. The invention of the first battery (or "voltaic pile") was in 1800 by

Alessandro Volta. Nowadays, batteries have become a common power source for many household

and industrial applications. According to a 2005 estimate, the worldwide battery industry generates

US$48 billion in sales each year, with 6% annual growth.There are two types of batteries: primary

batteries (disposable batteries), which are designed to be used once and discarded and secondary

batteries (rechargeable batteries), which are designed to be recharged and used multiple times.

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Fig no: 5.2 Battery

Miniature cells are used to power devices such as hearing aids and wristwatches whereas larger

batteries provide standby power for telephone exchanges or computer data centers.

The solar energy is converted to electrical energy by photo-voltaic cells. This energy is stored in

batteries during day time for utilizing the same during night time. This project deals with a

controlled charging mechanism which over charge, deep discharge and under voltage of the battery.

In this project a solar panel is used to charge a battery. Indications are also provide by

a Red LED off for fully charged battery while a set of red LEDs on to indicate under charged,

overloaded and deep discharge condition. Charge controller also uses MOSFET as power

semiconductor switch to ensure cut off the load in low battery or overload condition. A transistor is

used to bypass the solar energy to a dummy load

While the battery gets fully charged. This protects the battery from getting over charged.

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The requirement and use of electrical energy is increasing rapidly with technology development and

population growth. By using renewable and non-renewable sources, electrical energy is generated.

Multiple advantages of solar energy are the key factors behind the usage of solar charge

controller for various purposes in industrial applications. Solar charge controller is used for storing

the electrical power in batteries which is generated with the help of solar panels and further it can be

fed into loads.

A solar charge controller is basically a current or a voltage controller to charge the

battery and to protect the cells from overcharging. It directs the current and voltage comes from the

solar panels to charge the battery. Generally, 12V panels are put out in the approximate value of 16

to 20V, so in the overcharging condition the electric cells will be damaged if no regulation is

provided. For getting completely charged, electric storage devices require14 to 14.5V. The solar

charge controller circuits are available in all features, sizes and costs ranges from 4.5A to

60-80A.Here in this article we are going to discuss about solar charge controller using comparators

and as advancement to that solar charge controller circuit with microcontroller is also explained.

5.6COOLER FAN

Typical applications include climate control and personal thermal comfort (e.g., an

electric table or floor fan), vehicle and machinery cooling systems, ventilation, fume

extraction, winnowing (e.g., separating chaff of cereal grains), removing dust (e.g. in a vacuum

cleaner), drying (usually in combination with heat) and to provide draft for a fire. While fans are

often used to cool people, they do not actually cool air (if anything, electric fans warm it slightly due

to the warming of their motors), but work by evaporative cooling of sweat and increased

heat convection into the surrounding air due to the airflow from the fans. Thus, fans may become

ineffective at cooling the body if the surrounding air is near body temperature and contains high

humidity.

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Processors in most early x86-based computers, up to some of the early 486s, did not

need active ventilation. Power supplies needed forced cooling, and power supply fans also circulated

cooling air through the rest of the PC with the ATX standard. The byproduct of increased heat

generation is that the fan(s) need to move increasing amounts air and thus need to be more powerful.

Since they must move more air through the same area of space, fans will become more noisy.

Fans installed in a PC case can produce noise levels of up to 70 dB. Since fan noise

increases with the fifth power of the fan rotation speed, reducing rotations per minute (RPM) by a

small amount potentially means a large reduction in fan noise. This must be done cautiously, as

excessive reduction in speed may cause components to overheat and be damaged. If done properly

fan noise can be drastically reduced.

The common cooling fans used in computers use standardized connectors with two to four pins. The

first two pins are always used to deliver power to the fan motor, while the rest can be optional,

depending on fan design and type:

Power – nominally +12 V, though it may be variable depending on fan type and desired fan rotation

speed

Sense output from fan – outputs a signal that pulses twice for each rotation of the fan as a pulse train,

with the signal frequency proportional to the fan speed Control input – a pulse-width

modulation (PWM) input signal, which gives the ability to adjust the rotation speed on the fly

without changing the input voltage delivered to the cooling fan.The color of the wires connected to

these pins varies depending on the number of connectors, but the role of each pin is standardized and

guaranteed to be the same on any system. Cooling fans equipped with either two- or three-pin

connectors are usually designed to accept a wide range of input voltages, which directly affects the

rotation speed of the blades.

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FIGURE: 5.3 cooler fan

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5.7Electric motors

Electric motors are used to efficiently convert electrical energy into mechanical energy.

Magnetism is the basis of their principles of operation. They use permanent magnets,

electromagnets, and exploit the magnetic properties of materials in order to create these amazing

machines.

There are several types of electric motors available today. The following outline gives an

overview of several popular ones. There are two main classes of motors: AC and DC. AC motors

require an alternating current or voltage source (like the power coming out of the wall outlets in your

house) to make them work. DC motors require a direct current or voltage source (like the voltage

coming out of batteries) to make them work. Universal motors can work on either type of power. Not

only is the construction of the motors different, but the means used to control the speed and torque

created by each of these motors also varies, although the principles of power conversion are common

to both.

Motors are used just about everywhere. In our house, there is a motor in the furnace for the

blower, for the intake air, in the sump well, dehumidifier, in the kitchen in the exhaust hood above

the stove, microwave fan, refrigerator compressor and cooling fan, can opener, garbage disposer,

dish washer pump, clocks, computer fans, ceiling fans, and many more items. In industry, motors are

used to move, lift, rotate, accelerate, brake, lower and spin material in order to coat, paint, punch,

plate, make or form steel, film, paper, tissue, aluminum, plastic and other raw materials. They range in power ratings from less than 1/100 hp to over 100,000 hp. The rotate as slowly as 0.001 rpm to

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over 100,000 rpm. They range in physical size from as small as the head of a pin to the size of a

locomotive engine.

5.7.1 AC Motors

An AC motor is an electric motor that is driven by an alternating current. It consists of two

basic parts, an outside stationary stator having coils supplied with alternating current to produce a

rotating magnetic field, and an inside rotor attached to the output shaft that is given a torque by the

rotating field.

There are two types of AC motors, depending on the type of rotor used. The first is the

synchronous motor, which rotates exactly at the supply frequency or a sub multiple of the supply

frequency. The magnetic field on the rotor is either generated by current delivered through slip rings

or by a permanent magnet. The second type is the induction motor, which runs slightly slower than

the supply frequency. The magnetic field on the rotor of this motor is created by an induced current.

5.7.2 Types of Motors

5.7.2.1 Split Phase

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The split phase motor is mostly used for "medium starting" applications. It has start and run

windings, both are energized when the motor is started. When the motor reaches about 75% of its

rated full load speed, the starting winding is disconnected by an automatic switch.

Uses: This motor is used where stops and starts are somewhat frequent. Common applications of

split phase motors include: fans, blowers, office machines and tools such as small saws or drill

presses where the load is applied after the motor has obtained its operating speed.

5.7.2.2 Capacitor Start

This motor has a capacitor in series with a starting winding and provides more than double

the starting torque with one third less starting current than the split phase motor. Because of this

improved starting ability, the capacitor start motor is used for loads which are hard to start. It has

good efficiency and requires starting currents of approximately five times full load current. The

capacitor and starting windings are disconnected from the circuit by an automatic switch when the

motor reaches about 75% of its rated full load speed.

Uses: Common uses include: compressors, pumps, machine tools, air conditioners, conveyors,

blowers, fans and other hard to start applications.

5.7.2.3 Phase, Voltage & Rotation

Whether or not you can use a motor will likely depend on these factors.

5.7.2.4 Single Phase

Ordinary household wiring is single phase, alternating current. Each cycle peaks and dips as

shown. To run a three phase motor a phase converter must be used, usually this is not practical, it is

often less expensive to change the motor on a machine to a single phase style.

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Fig 5.5 block diagram

The speed of the AC motor is determined primarily by the frequency of the AC supply and the

number of poles in the stator winding, according to the relation:

Ns = 120F / p

Where

N s = Synchronous speed, in revolutions per minute

F = AC power frequency p = Number of poles per phase windin

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6.1 Solar Power Charge Controller Circuit using Comparators

The solar charge controller project is designed to store electrical energy in batteries

which is obtained by converting the solar energy into electrical energy with the help of

photo-voltaic cells during the daytime and to utilize this stored solar energy during night

time. For monitoring the voltage and load current of solar panels a set of op-amps are used

as comparators as shown in the block diagram.

Fig: 6.1 Solar Power Charge Controllers

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Different types of light emitting diodes are used to indicate the following conditions:

under voltage, overload and deep discharge conditions. To cut off the load in overload and

low battery conditions MOSFET is used as a power semiconductor switch. If the battery is

fully charged, then the solar energy is transferred to the dummy load with the help of a

transistor. This project can be further developed by using microcontroller.

6.2 PV PANEL

In a photovoltaic cell, light excites electrons to move from one layer to another

throughsemi-conductive silicon materials. This produces an electric current.Solar cells called

photovoltaics made from thin slices of crystalline silicon, gallium arsenide, or other

semiconductor materials convert solar radiation directly into electricity. Cells with conversion

efficiencies greater than 30 percent are now available. By connecting large numbers of these

cells into modules, the cost of photovoltaic electricity has been reduced to 20 to 30 cents

per kilowatt-hour. Americans currently pay 6 to 7 cents per kilowatt-hour for conventionally

generated electricity.

The simplest solar cells provide small amounts of power for watches and calculators. More

complex systems can provide electricity to houses and electric grids. Usually though, solar

cells provide low power to remote, unattended devices such as buoys, weather and

communication satellites, and equipment aboard spacecraft.

6.3 CHARGE CONTROLLER

A charge controller, charge regulator or battery regulator limits the rate at which electric

current is added to or drawn from electric batteries. It prevents overcharging and may prevent

against overvoltage, which can reduce battery performance or lifespan, and may pose a safety

risk. It may also prevent completely draining ("deep discharging") a battery, or perform

controlled discharges, depending on the battery technology, to protect battery life. The terms

"charge controller" or "charge regulator" may refer to either a stand-alone device,

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or to control circuitry integrated within a battery pack,battery-powered device, or battery

recharger.

A series charge controller sor series regulator disables further current flow into

batteries when they are full. A shunt charge controller or shunt regulator diverts excess

electricity to an auxiliary or "shunt" load, such as an electric water heater, when batteries are

full.

6.4 INVERTER

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 depend on the design of

the specific device or circuitry. The inverter does not produce any power; the power is provided by

the DC source.

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.

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Fig no: 6.2 Inverter

6.5 Input and output

Input voltage

A typical power inverter device or circuit requires a relatively stable DC power

source capable of supplying enough current for the intended power demands of the system. The

input voltage depends on the design and purpose of the inverter. Examples include:

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● 12 VDC, for smaller consumer and commercial inverters that typically run from a rechargeable

12 V lead acid battery.

● 24 and 48 VDC, which are common standards for home energy systems.

● 200 to 400 VDC, when power is from photovoltaic solar panels.

● 300 to 450 VDC, when power is from electric vehicle battery packs in vehicle-to-grid systems.

● Hundreds of thousands of volts, where the inverter is part of a high voltage direct current power

transmission system.

6.6 Output waveform

An inverter can produce a square wave, modified sine wave, pulsed sine wave, pulse width

modulated wave (PWM) or sine wave depending on circuit design. The two dominant

commercialized waveform types of inverters as of 2007 are modified sine wave and sine wave.

There are two basic designs for producing household plug-in voltage from a lower-voltage

DC source, the first of which uses a switching boost converter to produce a higher-voltage DC and

then converts to AC. The second method converts DC to AC at battery level and uses

a line-frequency transformer to create the output voltage.

Fig 6.3 Square wave

6.6.1 Square wave

This is one of the simplest waveforms an inverter design can produce and is best suited to

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low-sensitivity applications such as lighting and heating. Square wave output can produce

"humming" when connected to audio equipment and is generally unsuitable for sensitive electronics.

Fig 6.4 Sine wave

6.6.2 Sine wave

A power inverter device which produces a multiple step sinusoidal AC waveform is referred

to as a sine wave inverter. To more clearly distinguish the inverters with outputs of much less

distortion than the "modified sine wave" (three step) inverter designs, the manufacturers often use

the phrase pure sine wave inverter. Almost all consumer grade inverters that are sold as a "pure sine

wave inverter" do not produce a smooth sine wave output at all, just a less choppy output than the

square wave (one step) and modified sine wave (three step) inverters. In this sense, the phrases "Pure

sine wave" or "sine wave inverter" are misleading to the consumer. However, this is not critical for

most electronics as they deal with the output quite well. Where power inverter devices substitute for

standard line power, a sine wave output is desirable because many electrical products are engineered

to work best with a sine wave AC power source. The standard electric utility power attempts to

provide a power source that is a good approximation of a sine wave.

Sine wave inverters with more than three steps in the wave output are more complex and have

significantly higher cost than a modified sine wave, with only three steps, or square wave (one step)

types of the same power handling. Switch-mode power supply (SMPS) devices, such as personal

computers or DVD players, function on quality modified sine wave power. AC motors directly

operated on non-sinusoidal power may produce extra heat, may have different speed-torque

characteristics, or may produce more audible noise than when running on sinusoidal power.

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6.6.3 Modified sine wave

A "modified sine wave" inverter has a non-square waveform that is a useful rough

approximation of a sine wave for power translation purposes. Most inexpensive consumer power

inverters produce a modified sine wave rather than a pure sine wave.

The waveform in commercially available modified-sine-wave inverters is a square wave with

a pause before the polarity reversal, which only needs to cycle back and forth through a

three-position switch that outputs forward, off, and reverse output at the pre-determined frequency.

Switching states are developed for positive, negative and zero voltages as per the patterns given in

the switching Table 2. The peak voltage to RMS voltage ratio does not maintain the same

relationship as for a sine wave. The DC bus voltage may be actively regulated, or the "on" and "off"

times can be modified to maintain the same RMS value output up to the DC bus voltage to

compensate for DC bus voltage variations.

The ratio of on to off time can be adjusted to vary the RMS voltage while maintaining a

constant frequency with a technique called Pulse Width Modulation (PWM). The generated gate

pulses are given to each switch in accordance with the developed pattern to obtain the desired

output. Harmonic spectrum in the output depends on the width of the pulses and the modulation

frequency. When operating induction motors, voltage harmonics are usually not of concern;

however, harmonic distortion in the current waveform introduces additional heating and can produce

pulsating torques. Numerous items of electric equipment will operate quite well on modified sine

wave power inverter devices, especially loads that are resistive in nature such as traditional

incandescent light bulbs.

However, the load may operate less efficiently owing to the harmonics associated with a

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modified sine wave and produce a humming noise during operation. This also affects the efficiency

of the system as a whole, since the manufacturer's nominal conversion efficiency does not account

for harmonics. Therefore, pure sine wave inverters may provide significantly higher efficiency than

modified sine wave inverters.

Most AC motors will run on MSW inverters with an efficiency reduction of about 20%

owing to the harmonic content. However, they may be quite noisy. A series LC filter tuned to the

fundamental frequency may help. A common modified sine wave inverter topology found in

consumer power inverters is as follows:

An onboard microcontroller rapidly switches on and off power MOSFETs at high frequency

like ~50 kHz. The MOSFETs directly pull from a low voltage DC source (such as a battery). This

signal then goes through step-up transformers (generally many smaller transformers are placed in parallel to reduce the overall size of the inverter) to produce a higher voltage signal. The output of

the step-up transformers then gets filtered by capacitors to produce a high voltage DC supply.

Finally, this DC supply is pulsed with additional power MOSFETs by the microcontroller to produce

the final modified sine wave signal.

6.6.4 Other waveforms

By definition there is no restriction on the type of AC waveform an inverter might produce

that would find use in a specific or special application.

Output frequency

The AC output frequency of a power inverter device is usually the same as standard power

line frequency, 50 or 60 hertz. If the output of the device or circuit is to be further conditioned (for

example stepped up) then the frequency may be much higher for good transformer efficiency.

Output voltage

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The AC output voltage of a power inverter is often regulated to be the same as the grid line

voltage, typically 120 or 240 VAC, even when there are changes in the load that the inverter is

driving. This allows the inverter to power numerous devices designed for standard line power.

Some inverters also allow selectable or continuously variable output voltages.

Output power

A power inverter will often have an overall power rating expressed in watts or kilowatts. This

describes the power that will be available to the device the inverter is driving and, indirectly, the

power that will be needed from the DC source.

Smaller popular consumer and commercial devices designed to mimic line power typically range

from 150 to 3000 watts. Not all inverter applications are solely or primarily concerned with power

delivery; in some cases the frequency and or waveform properties are used by the follow-on circuit

or device.

Batteries

The runtime of an inverter is dependent on the battery power and the amount of power being

drawn from the inverter at a given time. As the amount of equipment using the inverter increases, the

runtime will decrease. In order to prolong the runtime of an inverter, additional batteries can be

added to the inverter When attempting to add more batteries to an inverter, there are two basic

options for installation: Series Configuration and Parallel Configuration.

Series configuration

If the goal is to increase the overall voltage of the inverter, one can daisy chain batteries in

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a Series Configuration. In a Series Configuration, if a single battery dies, the other batteries will not

be able to power the load.

Parallel configuration

Increase capacity and prolong the runtime of the inverter, batteries can be connected in

parallel. This increases the overall Ampere-hour (Ah) rating of the battery set. If a single battery is

discharged though, the other batteries will then discharge through it. This can lead to rapid discharge

of the entire pack, or even an over-current and possible fire. To avoid this, large paralleled batteries

may be connected via diodes or intelligent monitoring with automatic switching to isolate an

under-voltage battery from the others.

Applications

DC power source usage

Inverter designed to provide 115 VAC from the 12 VDC source provided in an automobile. The unit

shown provides up to 1.2 amperes of alternating current, or enough to power two sixty watt light

bulbs. An inverter converts the DC electricity from sources such as batteries or fuel cells to AC

electricity. The electricity can be at any required voltage; in particular it can operate AC equipment

designed for mains operation, or rectified to produce DC at any desired voltage. Uninterruptible

power supplies an uninterruptible power supply (UPS) uses batteries and an inverter to supply AC

power when mains power is not available. When mains power is restored, a rectifier supplies DC

power to recharge the batteries.

Electric motor speed control

Inverter circuits designed to produce a variable output voltage range are often used within

motor speed controllers. The DC power for the inverter section can be derived from a normal AC

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wall outlet or some other source. Control and feedback circuitry is used to adjust the final output of

the inverter section which will ultimately determine the speed of the motor operating under its

mechanical load.

Motor speed control needs are numerous and include things like: industrial motor driven equipment,

electric vehicles, rail transport systems, and power tools. (See related: variable-frequency drive )

Switching states are developed for positive, negative and zero voltages as per the patterns given in

the switching Table 1.The generated gate pulses are given to each switch in accordance with the

developed pattern and thus the output is obtained.

Power grid

Grid-tied inverters are designed to feed into the electric power distribution system. They

transfer synchronously with the line and have as little harmonic content as possible. They also need a

means of detecting the presence of utility power for safety reasons, so as not to continue to

dangerously feed power to the grid during a power outage.

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Fig 6.5 Internal view of Solar Inverter

Internal view of a solar inverter. Note the many large capacitors (blue cylinders), used to store

energy briefly and improve the output waveform.

6.7 Solar inverter:

A solar inverter is a balance of system (BOS) component of a photovoltaic system and can be

used for both, grid-connected and off-grid systems. Solar inverters have special functions adapted for

use with photovoltaic arrays, including maximum power point

tracking andanti-islanding protection. Solar micro-inverters differ from conventional converters, as

an individual micro-converter is attached to each solar panel. This can improve the overall efficiency

of the system. The output from several micro inverters is then combined and often fed to the electrical grid.

6.8 Induction heating

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Inverters convert low frequency main AC power to higher frequency for use in induction

heating. To do this, AC power is first rectified to provide DC power.

The inverter then changes the DC power to high frequency AC power. Due to the reduction

in the number of DC sources employed, the structure becomes more reliable and the output voltage has higher resolution due to an increase in the number of steps so that the reference sinusoidal

voltage can be better achieved.

This configuration has recently become very popular in AC power supply and adjustable

speed drive applications. This new inverter can avoid extra clamping diodes or voltage balancing

capacitors.

Results and Discussion

The output of the project is Comfort thermal conditions achieved in the living room. That is

room temperature up to 25o C and relative humidity of 60%.

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CHAPTER-7

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CHAPTER-7

CALCULATIONS

● Hence selected Fan Specification: 230v, 50Hz, 35W

So to run 40W fan on for 1 hour will take

40*1=40Wh from the battery (Battery capacity is measured in Amp hours)

● 10Ah, 12v battery the watt hours is given by

P=V*I

V=12v and I=40Ah

P= 40*12=480Wh

So, the 40W centrifugal fan runs for

480/40=12h

This means the battery could supply 40W fan for 12 hours

● To calculate the energy it can supply to the battery, multiply watts by the hours exposed to

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sunlight, then multiply the result by 0.85(This factor allows for natural system losses)

For the solar 10W panel in 6 hours sunshine, 10*6*0.85 = 57Wh

For 1 hour, 10*1*0.85 = 8.5Wh

So the solar panel of 10W and battery of 40Ah are selected (Office purpose)

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CHAPTER-8

CHAPTER-8

ADVANTAGES AND LIMITATION

ADVANTAGES

● The demand for cooler is likely to increase because worldwide temperature increases. While

using soaring demand in energy, count on costs in order to continually advance.

● Any a lot more feasible, long-term solution lies in harnessing solar energy to cool our own

atmosphere through any solar air cooler solar panel array. Whenever you think about the

idea, the days when you need air-cooling most are generally those days when the solar

reaches its best.

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● The solar air cooler can work precisely. Solar air cooler makes use of the solar panel that

soaks up and traps heat from the sun within the form of thermal power simply by warming

normal water.

● This power can be delivered to the solar air cooler along with heats up the solution causing it

to steam. Since it cools it creates a cooling effect that's taken into an additional water loop

● Solar air conditioning provides a great package involving benefits. Installation expenses can

be reduced through tax credits, deductions and also refunds. .

● In humid regions, desiccant dehumidification can reduce electricity demand considerably by

providing a drier, more comfortable, and clean indoor environment with a lower energy bill.

Desiccant systems allow more fresh air into buildings, thus improving indoor air quality

without using more energy.

● Desiccant systems also displace chlorofluorocarbon-based cooling equipment, the emissions

from which contribute to the depletion of the Earth's ozone layer.

● Desiccant dehumidification technology provides a method of drying air before it enters a

conditioned space. When combined with conventional vapour compression systems,

desiccant dehumidification systems are a cost-effective means of supplying cool, dry, filtered

air.

LIMITATIONS

● In cloudy conditions solar collector cannot work properly as sun rays are not uniform.

● Slow working process as less moving parts.

● Process totally dependent on supply of suns radiation.

● Less efficient due to intermittent supply of suns radiation.

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CONCLUSION

Comparing the cost of this product with the existing products in the market is solar product

appeals better and affordable by common people.

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This solar product perfectly suits for villages, schools and offices and thus an alternate to the

power cut problems. It comprises of many attractive features such as usage of solar energy, cooler

and cooling cabin at lower cost. It is eco friendly and natural, electricity savers.

Durability of the product is more thus minimizing the cost. No electricity is used so this

product saves the energy and saves environment from getting polluted.

FUTURES SCOPE

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Where Power Energy not available in that areas Solar Energy is adopted to meet the needs.

Solar Energy is alternative to conventional Energy due to more advantages like eco-friendly, reduce

the green house effects no pollutant and low cost.

It is cost effective as the whole cost of the project becomes very less and cheap as compared

to other traditional electric air conditioner and it is less bulky too.

However, more further scope to air cooler by using solar energy in remoted areas we

recommend to society to use solar energy

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REFERENCES

1. Farhan a. khmamas, 2012, “Improving the environmental cooling for air-coolers by

using the indirect-cooling method” ARPN journal of engineering and applied

sciences, vol. 5, No. 2, page No. 66-73.

2. A S Alosaimy, 2013 “Application of Evaporative Air Coolers Coupled With Solar

Water Heater for Dehumidification of Indoor Air” International Journal of

Mechanical & Mechatronics Engineering, Vol:13 No:01 page no. 60- 68.

3. “Basic Photovoltaic Principles and Methods” SERI/SP- 290-1448 Solar Information

Module 6213 Published February 1982 page. No. 9-15.

4. Arora and Domkundwar, A text book “The course on power plant engineering”.

5. B. Srinivas Reddy, K Hemachandra Reddy, “Thermal engineering data hand book”.

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