Project Report On Solar Air Conditioner

Solar Air Conditioner
Project Report
Submitted in partial fulfillment of the requirements for the degree of
Bachelor of Technology (B.Tech)
Submitted by:
Anand Kumar [ME/13/710]
May, 2017

Project Report
Submitted in partial fulfillment of the requirements for the degree of
Bachelor of Technology (B.Tech)
Submitted by:
Anand Kumar [ME/13/710]
May, 2017
Under the Supervision of Mr. Deepak Sharma

CERTIFICATE
This is to certify that the Project titled Solar Air Conditioner and submitted by Anand
Kumar having Roll No ME/13/710 for the partial fulfillment of the requirements for the
degree of Bachelor of Technology (B.Tech), embodies the bonafide work done by him
under my supervision.
___________________________
Signature of the Project Coordinator
Place: _______________________
Date: _______________________

Acknowledgement
This report gives the details of the project work done in VII and VIII semester for partial
fulfillment of the requirements for the degree of Bachelor of Technology (B.Tech), under
the supervision of Mr. Deepak Sharma.
I am very grateful to my supervisor Mr. Deepak Sharma for his help and able guidance
for the project. I am very thankful to my institute, for providing me resources and
facilities to help in the project.
__________________________
Signature of the Student
Name: ____________________
Date: _____________________

Table of Contents
1 INTRODUCTION ...................................................................................................................1
2 FEASIBILITY REPORT.........................................................................................................3
3 REQUIREMENT SPECIFICATION ....................................................................................20
2 DESIGN SPECIFICATION ..................................................................................................36
5 CONCLUSION......................................................................................................................51
6 REFERENCES ......................................................................................................................52
7 CHECKLIST..........................................................................................................................53

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1 INTRODUCTION
An environmental control system utilizing solar energy would generally be more cost
effective if it were used to provide both heating and cooling requirements in the building
it serves. Various solar powered heating and cooling systems have been tested
extensively, but solar powered air-conditioners have received little more than short-term
demonstration attention.
Solar cooling technologies collect the thermal energy from the sun and use this heat to
provide cold air for residential, commercial, institutional and manufacturing buildings.
These technologies displace the need to use electricity or natural gas. Today, Countries
across the globe are at work manufacturing and installing solar heating and cooling
systems that significantly reduce our dependence on imported fuels. We need smart
policies to expand this fast growing, job producing sector.
It uses solar energy to produce cold or hot air. This technology can be used to reduce the
energy consumption environmental impact of mechanical cooling system. A significant
advantage of this system is, it has no moving parts consequently they are noiseless, non-
corrosive, cheap to maintain, long lasting in addition to being environmentally friendly
with zero ozone depletion as well as global warming potentials.
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 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.

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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 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.

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FEASIBILITY Report
May 1, 2017
Anand Kumar
[ME/13/710]

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1 General Information
1.1 Purpose
1.2 Scope
The need for renewable energy sources is on the rise because of the acute energy crisis in
the world today. Solar energy is a vital untapped resource in a tropical country like ours.
The main hindrance for the penetration and reach of solar PV systems is their low
efficiency and high capital cost.
a) Institutional buildings, such as schools, colleges, universities, libraries, hospitals,
nursing homes, museums, indoor stadium, cinema theatres etc.
b) Commercial buildings, such as offices, stores and shopping centers, supermarkets,
departmental stores, restaurants and others.
c) Residential buildings, including hotels, motels, single family and multifamily low
rise buildings of three or fewer stories above grade.
d) Manufacturing buildings, which manufacture and stores products for example
medicines
e) Desert Areas.
f) In remote villages where electricity is not present.
Air conditioning systems are mainly for the occupant’s health and comfort. They are
often called comfort air conditioning systems.
The project involves the development of a suitable cooling module designed with a Solar
AC to cool the surrounding air. This cooling system needed to be powered up by a DC
power supply, which is designed or using a suitable off-shelf power supply.

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The project scope involves the following elements:
 Sizing and Designing of the Solar AC
 Selection of the TECs
 Selection of Fans and Heat sinks
 DC power supply design with temperature control.
 Prototype Assembly and Fabrication.
 Temperature measurements for testing.
 Power supply testing and troubleshooting.
1.3 Project References
 Henning, H.M., Solar-Assisted Air Conditioning in Buildings, Springer-Verlag Wien
New York, 2007
 Planning and Installing Solar Thermal Systems, A guide for installer, architects and
engineers, James & James Ltd, UK, 2007
 Annett K., Solar Air conditioning Technologies and Potentials, Intersolar North
America, July 16, 2008
 Goldsmid H. (1986). Electronic Refrigeration. London:Pion
 Mollar(2003). Themoelectric Cooler Selection Procedure. Retrieved June 2006.
 Bansal PK, Martin A, Comparative Study of Vapour Compression, Thermoelectric
and Absorption Refrigerator-Rs. Int J Energy Res 2000; 24(2):93-107.
 Vashaee, And A. Shakouri, “Electronic and Thermoelectric Transport in
Semiconductor and Metallic Superlattices,” Journal of Applied Physics, Vol. 95,
No.3, pp. 1233- 1245, February 2004.
 Ancey, M. Gshwind, New Concept of Integrated Peltier Cooling Device for the
Preventive Detection of Water Condensation”, Sensors and Actuators B 26-27 (1995)
Pp. 303-307.
 Prof. Vivek R. Gandhewar, Miss. Priti G. Bhadake, Mr. Mukesh P. Mangtani
“Fabrication of Solar Operated Heating and Cooling System Using Thermo-Electric
Module”, ISSN: 2231-5381. International Journal of Engineering Trends and
Technology (IJETT) - Volume4 Issue4- April 2013
 Dai Yj, Wang Rz, Ni L. Expr. Investigation on A Thermo-Electric Refrigerator
Driven By Solar Cells. Renew Energy 2003; 28:949–59.

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 Field Rl. Photovoltaic / Thermoelectric Refrigerator for Medicine Storage for
Developing Countries. Sol Energy 1980; 25(5):4457.
1.4 Acronyms and Abbreviations
TEC-Thermoelectric Cooling
Q stands for heat energy
V- Voltage
I- Current
W- Watt
GW- Gigawatt
mA- Milliamps
Amp- Ampere
1.5 Points of Contact
1.5.1 Information
 Alok Kishor Suman [ME/13/706]
 Anand Kumar [ME/13/710]
 Ankit Sharma [ME/13/749]
1.5.2 Coordination
 Mentor – Mr. Deepak Sharma (Mechanical Engineering)
 Technical – Mr. Amit Dahiya (Mechanical Engineering)
 Technical – Ms. Arpita Asthana (Mechanical Engineering)
 Technical – Mr. Ajmer Singh (Mechanical Engineering)
 Technical – Ms. Rekha Chugh (Electrical Engineering)

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2 Management Summary
2.1 Environment
India is densely populated and has high solar insulation, an ideal combination for using
solar power in India. In the solar energy sector, some large projects have been proposed,
and a 35,000 km2
(14,000 sq m) area of the ‘Thar’ Desert has been set aside for solar
power projects, sufficient to generate 700 to 2,100 GW. Also India's Ministry of New
and Renewable Energy has released the JNNSM Phase 2 Draft Policy, by which the
Government aims to install 10 GW of Solar Power and of this 10 GW target, 4 GW
would fall under the central scheme and the remaining 6 GW under various State specific
schemes.
2.2 Organizations Involved
SBIT Sonepat, Haryana.
2.3 Materials Required
2.3.1 Peltier Module
Peltier module is a device which works on the principle of Peltier effect. Its one side is
heated and one side can be kept cold by using electricity. In our project we use 12 volt
and 3 ampere current rating Peltier module though in market there are different types of
Peltier module is available. It is one of the important parts of our project.
2.3.2 Solar Panel
Solar panel is a panel which basically converts solar energy into electric energy with the
help of photovoltaic material. There are different types of solar panel available in the
market but for our project we will use 3W, 10.5 volt and 0.24A rating solar panel.
2.3.3 Battery
Battery is used to store energy which will be further used in Peltier module. We will use
12 volt lead acid rechargeable having 6.8 amp rating.
2.3.4 DPDT switch
A Double Pole Double Throw (DPDT) switch is a switch that has 2 inputs and 4 outputs;
each input has 2 corresponding outputs that it can connect to. Each of the terminals of a
double pole double switch can either be in 1 of 2 positions. This makes the double pole
double throw switch a very versatile switch. With 2 inputs, it can connect to 4 different
outputs. It can reroute a circuit into 2 different modes of operation.

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A Double Pole Double Throw Switch is actually two single pole double throw (SPDT)
switches.
 10 Amp rating
2.3.5 Aluminium Sheet
Aluminum is a soft and ductile material, which is reasonably priced and readily available.
However, aluminium is an excellent heat conductor so care would have to be taken to
insulate the container. So the container in which we keep water is made of aluminium.
2.3.6 MDF Board, Machine Screw, Glue Stick, PVC wire etc.
It supports the whole equipment.
2.3.7 Diode
IN4007, ¼ watt
2.3.8 PCB
A printed circuit board (PCB) mechanically supports and electrically connects electronic
components using conductive tracks, pads and other features etched from copper
sheets laminated onto a non-conductive substrate.
2.3.9 Power Supply
12V–1 Amp rating for battery charging
2.3.10 Rectifier
Rectifier is a device which converts the A.C. to Direct current. Rectifier is used when we
apply A.C. on place of D.C. So there is need to convert the A.C. to D.C.
Fig. 1. Rectifier
2.3.11 Heat Sink with Cooling Fan
It is used to increase heat transfer rate. The cooling fan is having 12 volt motor and is 200
mA rating. A heat sink (also commonly spelled heatsink) is a passive heat exchanger that
transfers the heat generated by an electronic or a mechanical device to a fluid medium,

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often air or a liquid coolant, where it is dissipated away from the device, thereby allowing
regulation of the device's temperature at optimal levels.
A heat sink is designed to maximize its surface area in contact with the cooling medium
surrounding it, such as the air. Air velocity, choice of material, protrusion design and
surface treatment are factors that affect the performance of a heat sink.
Fig. 2. Heat sink with cooling fan
2.4 Performance Objectives (Efficiency)
Solar AC performance depends on the following factors:
 The temperature of the cold and hot sides.
 Thermal and electrical conductivities of the device’s materials.
 Contact resistance between the TE device and heat source/heat sink.
 Thermal resistance of the heat sink.
2.5 Assumptions and Constraints
In our projects we will prepare a solar AC which is different from our conventional AC.
It basically works on solar energy. It is very challenging to complete the conventional AC
that we already have. But its scope is very bright in future as it usage solar energy which
is abundantly available. We will use Peltier module which is very costly but further
improvement in its technology will make this product very popular.

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3 Proposed System
3.1 Methodology (Basic Principle involved)
The project implemented a structured system analysis and design methodology approach
to achieve the project objectives. Block system analysis of the project is shown below
(Figure 1) with the aid of a straightforward block diagram. Ambient air is blown out by
the blower through a duct to the TECs. TECs are sandwiched in between heat sinks. Cold
air is blown out from one end of the cold heat sinks. The TECs were powered by a power
supply.
Thermoelectric cooling uses the Peltier effect to create a heat flux between the junctions
of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump
is a solid-state active heat pump which transfers heat from one side of the device to the
other, with consumption of electrical energy, depending on the direction of the current.
Such an instrument is also called a Peltier device, Peltier heat pump, solid state
refrigerator, or thermoelectric cooler (TEC). They can be used either for heating or for
cooling (refrigeration), although in practice the main application is cooling. It can also be
used as a temperature controller that either heats or cools.
This technology is far less commonly applied to refrigeration than vapor-compression
refrigeration. The main advantages of a Peltier cooler (compared to a vapor-compression
refrigerator) are its lack of moving parts or circulating liquid, near-infinite life and
invulnerability to potential leaks, and its small size and flexible shape (form factor). Its
main disadvantage is high cost and poor power efficiency. Many researchers and
companies are trying to develop Peltier coolers that are both cheap and efficient.
A Peltier cooler can also be used as a thermoelectric generator. When operated as a
cooler, a voltage is applied across the device, and as a result, a difference in temperature
will build up between the two sides. When operated as a generator, one side of the device
is heated to a temperature greater than the other side, and as a result, a difference in
voltage will build up between the two sides (the Seebeck effect). However, a well
designed Peltier cooler will be a mediocre thermoelectric generator and vice-versa, due to
different design and packaging requirements.

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Fig. 3. Block diagram of the thermoelectric Solar AC
3.2 Description of Design of the Proposed System / Model
3.2.1 Design Process
Our team proceeded with the design process through a series of steps. These steps were:
identification of the problem, analyze problem, brainstorm ideas, decide upon a design
selection, and implement design. Redesign if necessary.
The main design considerations were:
 Heat Transfer Methods
 Geometry
 Materials
 Module
The following section will discuss these considerations.
3.2.2 Heat Transfer Methods
There are several methods which can be employed to facilitate the transfer of heat from
the surface of the thermoelectric to the surrounding. These methods are described in the
following three sections.
3.2.2.1 Natural Convection
Natural convection consists of an arrangement similar to forced convection except there
is no fan to drive airflow through the heat sink. This results in significantly reduced

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convection coefficients. The advantage of this arrangement is the fact that there are no
moving parts.
3.2.2.2 Liquid Cooled
The heat is removed from the surface of the thermoelectric module through the use of a
heat exchanger. Through the heat exchanger a fluid is passed to remove the heat coming
from the thermoelectric. The fluid is then passed through another heat exchanger where
the heat is dissipated to the surrounding environment and the cycle is repeated. This
method provides the highest rate of cooling due to the superior thermal conductivity of
liquid over gas.
3.2.2.3 Forced Convection
In this arrangement a finned heat sink would be directly attached to the surface of the
thermoelectric module. An electrically driven fan would provide turbulent airflow over
and through the heat sink to remove the heat by forced convection.
3.2.3 Geometry
Two main geometries were considered for the device. The first was a cube. The
advantage of this choice is its simplicity to build and insulate. A door can easily be
attached to one of the sides. Finally any insulation, thermoelectric modules or heat sinks
are easily fastened to the sides. The second choice for cooler geometry was a cylinder.
The advantage found with this shape is that it has the largest volume to surface area ratio
of the two designs considered. This is a good property when the objective is to minimize
heat loss.
3.2.4 Controller
The job of the controller is to regulate the amount of power which is being sent to the
thermoelectric. It bases this amount on the results of testing the interior temperature and
comparing it with a desired set point temperature. There are several different types of
controllers which can be employed to regulate the power.
3.2.4.1 On/Off
On/off controllers turn on or off depending on the temperature of the system relative to a
value set by the user. If the system is at a higher temperature than the desired value the
thermoelectric is turned on. If the system is cooler than desired the thermoelectric is
turned off. In this case the thermoelectric receives either the maximum power it can
handle or no power at all. This is undesirable as this type of cycling is very hard on the
physical system.

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3.2.4.2 Set Point/Manual
Manual control involves setting a desired current through the thermoelectric and allowing
that current to continue flowing as long as the device is operating. This method does not
give very accurate control of the temperature in the system.
3.2.5 Materials
We explored three different materials for the construction of the outer casing and frame
of the device. These were aluminum, sun board, and MDF.
3.2.5.1 Aluminium Sheet
However, aluminum is an excellent heat conductor so care would have to be taken to
insulate the container. Building the outer casing and frame could pose a problem as
welding aluminum is difficult because the material is prone to burn through.
3.2.5.2 Sun Board
Sun board or Foam board is a very strong, light, and easily cut sheet material used for the
mounting of vinyl prints, as backing in framing, and for painting. It usually has three
layers an inner layer of polystyrene foam and a white clay coated paper on the outside.
3.2.5.3 MDF Board
Medium-density fibreboard (MDF) is an engineered wood product made by breaking
down hardwood or softwood residuals into wood fibres, often in a defibrator, combining
it with wax and a resin binder, and forming panels by applying
high temperature and pressure. MDF is generally denser than plywood. It is made up of
separated fibres, but can be used as a building material similar in application to plywood.
It is stronger and much denser than particle board.
heated and one side can be kept cold by using electricity.
In our project we use 12 volt and 3 ampere current rating Peltier module though in market
there are different types of Peltier module is available .It is one of the important part of
our project.

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Fig. 4. Peltier Module
By applying a low voltage DC power to a TE module, heat will be moved through the
module from one side to the other. One module face, therefore, will be cooled while the
opposite face is simultaneously heated. It is important to note that this phenomenon may
be reversed whereby a change in the polarity (plus and minus) of the applied DC voltage
will cause heat to be moved in the opposite direction. Consequently, a thermoelectric
module may be used for both heating and cooling thereby making it highly suitable for
precise temperature control applications. A thermoelectric module can also be used for
power generation. In this mode, a temperature differential applied across the module will
generate a current.
A practical thermoelectric module generally consists of two or more elements of n and p-
type doped semiconductor material that is connected electrically in series and thermally
in parallel. These thermoelectric elements and their electrical interconnects typically are
mounted between two ceramic substrates. The substrates hold the overall structure
together mechanically and electrically insulate the individual elements from one another
and from external mounting surfaces. Most thermoelectric modules range in size from
approximately 2.5-50 mm (0.1 to 2.0 inches) square and 2.5-5mm (0.1 to 0.2 inches) in
height. A variety of different shapes, substrate materials, metallization patterns and
mounting options are available.
Fig. 5. Diagram of a Thermoelectric Module

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The schematic diagram above shows a typical thermoelectric module assembly. Both N-
type and P-type Bismuth Telluride thermoelectric materials are used in a thermoelectric
cooler. This arrangement causes heat to move through the cooler in one direction only
while the electrical current moves back and forth alternately between the top and bottom
substrates through each N and P element. N-type material is doped so that it will have an
excess of electrons (more electrons than needed to complete a perfect molecular lattice
structure) and P-type material is doped so that it will have a deficiency of electrons
(fewer electrons than are necessary to complete a perfect lattice structure). The extra
electrons in the N material and the “holes” resulting from the deficiency of electrons in
the P material are the carriers which move the heat energy through the thermoelectric
material. Most thermoelectric cooling modules are fabricated with an equal number of N-
type and P-type elements where one N and P element pair form a thermoelectric
“couple.” For example, the module illustrated above has two pairs of N and P elements
and is termed a “two-couple module”.
Cooling capacity (heat actively pumped through the thermoelectric module) is
proportional to the magnitude of the applied DC electric current and the thermal
conditions on each side of the module. By varying the input current from zero to
maximum, it is possible to regulate the heat flow and control the surface temperature.
3.3 Time and Resource Costs
Our projects will take approximately four months time including all time taken in
funding, shopping of components and finishing the final projects. The estimation of total
cost is all about five thousand rupees.
3.4 Rationale for Recommendations
We recommend our projects because of the following reasons:
 It uses renewable source of energy, which is abundantly available.
 Ability to lower temperature below ambient.
 Heat transport controlled by current input.
 Able to operate in any orientation.
 Compact sizes make them useful for applications where size or weight is a
constraint.
 Ability to alternate between heating and cooling.
 Excellent cooling alternative to vapor compression coolers for systems that are
sensitive to mechanical vibration.

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4 Final Project Design
Fig. 6. Solar AC

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5 Alternative Mechanism/ Design
5.1 Description of [Alternative Mechanism / Design]
The heat produced by a computer chip can be use to provide the electricity to run a fan
that cools the chip. The fan uses a TE device operating on the Seebeck Effect to convert
the heat to electricity.
When a laptop is running on batteries, the electricity used to power the fan comes from
the battery. Therefore, to conserve battery life, a thermoelectric power generator is a good
alternative.
A design such as the one below may be used.
Fig. 7. TE powered microprocessor cooler – conceptual design

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Requirement Specification
May 1, 2017
Anand Kumar
(ME/13/710)

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Approved By
Approvals should be obtained from faculty/ HOD
Faculty comments :
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
______
Faculty Name: Faculty Signature
_____________________________ _________________________
Project Coordinator Project Coordinator Signature
_____________________________ _________________________

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1 Introduction
1.1 Purpose
1.2 Project Scope
medicines
e) Desert Areas.
Air conditioning systems are mainly for the occupant’s health and comfort. They are
often called comfort air conditioning systems.

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1.3 References
 Henning, H.M., Solar-Assisted Air Conditioning in Buildings, Springer-Verlag
Wien New York, 2007
 Planning and Installing Solar Thermal Systems, A guide for installer, architects
and engineers, James & James Ltd, UK, 2007
 Bansal PK, Martin A, Comparative Study of Vapour Compression,
Thermoelectric and Absorption Refrigerator-Rs. Int J Energy Res 2000; 24(2):93-
107.
No.3, pp. 1233- 1245, February 2004.
Preventive Detection of Water Condensation”, Sensors and Actuators B 26-27
(1995) Pp. 303-307.
“Fabrication of Solar Operated Heating and Cooling System Using Thermo-
Electric Module”, ISSN: 2231-5381. International Journal of Engineering Trends
and Technology (IJETT) - Volume4 Issue4- April 2013
 Dai Yj, Wang Rz, Ni L. Expr. Investigation on A Thermo-Electric
Refrigerator Driven By Solar Cells. Renew Energy 2003; 28:949–59.

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2 Overall Description
2.1 Product Perspective
 To make our world a greener and pollution free place.
 To reduce the burden of electricity.
 Desert Areas.
 In remote villages where electricity is not present.
 Institutional buildings, such as schools, colleges, universities, hospitals, nursing
homes.
 Commercial buildings, such as offices, stores and shopping centres, supermarkets,
2.2 Product Features
It uses solar energy to produce cooled air. This technology can be used to reduce the
2.3 Operating Environment
Solar AC works on solar energy so it is highly beneficial for places where solar energy is
present. It is also beneficial for the places where electricity is not present.
2.3.1 General Scenario of Environmental Conditions
In today’s time, there are emerging several environmental issues due to excessive stress
on fossil fuels and other commercialized pollution causing sources. One of the major
contributor to the pollution is the Fuel Combustion pollutants namely CO2, SO2 etc.
Adding to this list, air-conditioning materials like CFC’s have also contributed a lot to the
pollution. Increased usage has lead to the following impact on the environment:
 Global Warming
 Ozone Depletion
 Climate Changes

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2.3.1.1 Global Warming
Global warming refers to an unequivocal and continuing rise in the average temperature
of Earth's climate system. Since 1971, 90% of the warming has occurred in the oceans.
Despite the oceans' dominant role in energy storage, the term "global warming" is also
used to refer to increases in average temperature of the air and sea at Earth's surface.
Since the early 20th century, the global air and sea surface temperature has increased
about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980. Each of
the last three decades has been successively warmer at the Earth's surface than any
preceding decade since 1850.
Scientific understanding of the cause of global warming has been reported by scientists
that Global warming is being caused by increasing concentrations of greenhouse gases
produced by human activities. The largest driver of global warming is carbon dioxide
(CO2) emissions from fossil fuel combustion, cement production, and land use changes
such as deforestation.
2.3.1.2 Ozone Depletion
The ozone layer is a belt of naturally occurring ozone gas that sits 9.3 to 18.6 miles (15 to
30 kilometers) above Earth and serves as a shield from the harmful ultraviolet B radiation
emitted by the sun.
Ozone is a highly reactive molecule that contains three oxygen atoms. It is constantly
being formed and broken down in the high atmosphere, 6.2 to 31 miles (10 to 50
kilometers) above Earth, in the region called the stratosphere. Today, there is widespread
concern that the ozone layer is deteriorating due to the release of pollution containing the
chemicals chlorine and bromine. Such deterioration allows large amounts of ultraviolet B
rays to reach Earth, which can cause skin cancer and cataracts in humans and harm
animals as well.
Extra ultraviolet B radiation reaching Earth also inhibits the reproductive cycle of
phytoplankton, single-celled organisms such as algae that make up the bottom rung of the
food chain. Biologists fear that reductions in phytoplankton populations will in turn
lower the populations of other animals. Researchers also have documented changes in the
reproductive rates of young fish, shrimp, and crabs as well as frogs and salamanders
exposed to excess ultraviolet B.
Chlorofluorocarbons (CFCs), chemicals found mainly in spray aerosols heavily used by
industrialized nations for much of the past 50 years, are the primary culprits in ozone
layer breakdown. When CFCs reach the upper atmosphere, they are exposed to
ultraviolet rays, which cause them to break down into substances that include chlorine.
The chlorine reacts with the oxygen atoms in ozone and rips apart the ozone molecule.

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One atom of chlorine can destroy more than a hundred thousand ozone molecules,
according to the U.S. Environmental Protection Agency.
The ozone layer above the Antarctic has been particularly impacted by pollution since the
mid-1980s. This region’s low temperatures speed up the conversion of CFCs to chlorine.
In the southern spring and summer, when the sun shines for long periods of the day,
chlorine reacts with ultraviolet rays, destroying ozone on a massive scale, up to 65
percent. This is what some people erroneously refer to as the "ozone hole." In other
regions, the ozone layer has deteriorated by about 20 percent.
About 90 percent of CFCs currently in the atmosphere were emitted by industrialized
countries in the Northern Hemisphere, including the United States and Europe. These
countries banned CFCs by 1996, and the amount of chlorine in the atmosphere is falling
now. But scientists estimate it will take another 50 years for chlorine levels to return to
their natural levels.
2.3.1.3 Climate Changes
Climate change is a change in the statistical distribution of weather patterns when that
change lasts for an extended period of time (i.e., decades to millions of years). Climate
change may refer to a change in average weather conditions, or in the time.

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3 System Features
3.1 Functional Requirements
The functional requirements for Solar AC are described below. These include the
essential part list which is used to make a Solar AC. There is the list of components
which is used in this project.
 Solar Panel
 Battery
 Medium Density Fiber (MDF) Board
 Peltier Module
 Exhaust Fan
 Heat Sink
 Cooling Fan
 Aluminium Sheet
 DPDT Switch
 PCB
 Power Supply
 Machine Screw
 Glue Stick
 Electric Tape
 Sun Board
 PVC Wire
 Peltier Plate Assembly
 Charge Control Circuit
 LED
 Diode
 Resistance
 Motor

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4 External Interface Requirements
4.1 Hardware Interfaces
heated and one side can be kept cold by using electricity. In our project we use 12 volt
and 3 ampere current rating Peltier module though in market there are different types of
Peltier module is available .It is one of the important part of our project.
Fig. 8. Cutway of a Peltier Module
By applying a low voltage DC power to a TE module, heat will be moved through the
module from one side to the other. One module face, therefore, will be cooled while the
opposite face is simultaneously heated. It is important to note that this phenomenon may
be reversed whereby a change in the polarity (plus and minus) of the applied DC voltage
will cause heat to be moved in the opposite direction. Consequently, a thermoelectric
module may be used for both heating and cooling thereby making it highly suitable for
precise temperature control applications. A thermoelectric module can also be used for
power generation. In this mode, a temperature differential applied across the module will
generate a current.
A practical thermoelectric module generally consists of two or more elements of n and p-
type doped semiconductor material that is connected electrically in series and thermally
in parallel.
These thermoelectric elements and their electrical interconnects typically are mounted
between two ceramic substrates. The substrates hold the overall structure together

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mechanically and electrically insulate the individual elements from one another and from
external mounting surfaces. Most thermoelectric modules range in size from
approximately 2.5-50 mm (0.1 to 2.0 inches) square and 2.5-5mm (0.1 to 0.2 inches) in
height. A variety of different shapes, substrate materials, metallization patterns and
mounting options are available.
The schematic diagram above shows a typical thermoelectric module assembly. Both N-
type and P-type Bismuth Telluride thermoelectric materials are used in a thermoelectric
cooler. This arrangement causes heat to move through the cooler in one direction only
while the electrical current moves back and forth alternately between the top and bottom
substrates through each N and P element. N-type material is doped so that it will have an
excess of electrons (more electrons than needed to complete a perfect molecular lattice
structure) and P-type material is doped so that it will have a deficiency of electrons
(fewer electrons than are necessary to complete a perfect lattice structure). The extra
electrons in the N material and the “holes” resulting from the deficiency of electrons in
the P material are the carriers which move the heat energy through the thermoelectric
material. Most thermoelectric cooling modules are fabricated with an equal number of N-
type and P-type elements where one N and P element pair form a thermoelectric
“couple.” For example, the module illustrated above has two pairs of N and P elements
and is termed a “two-couple module”.
Cooling capacity (heat actively pumped through the thermoelectric module) is
proportional to the magnitude of the applied DC electric current and the thermal
conditions on each side of the module. By varying the input current from zero to
maximum, it is possible to regulate the heat flow and control the surface temperature.
Peltier Effect- When a voltage or DC current is applied to two dissimilar conductors; a
circuit can be created that allows for continuous heat transport between the conductor’s
junctions. The Seebeck Effect is the reverse of the Peltier Effect. By applying heat to two
different conductors a current can be generated. The Seebeck Coefficient is given by:
Where,  is the electric field.
The current is transported through charge carriers (opposite the whole flow or with
electron flow). Heat transfer occurs in the direction of charge carrier movement.
Solar AC devices are favorable in electronics cooling systems because of their high
reliability, flexibility in packaging and integration, low weight and ability to maintain a
low junction temperature, even below ambient temperature.
dxdT
x
/

 

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Also, other cooling devices that can fit the tiny spaces required for electronics cooling,
such as, a capillary loop heat or a miniature scale vapor compression refrigerator are not
commercially available.
Disadvantages of these devices are the limit to their cooling capacity limit and coefficient
of performance which may be restrictive in the future when heat transfer demands
become much larger.
4.1.2 Solar Panel
Solar panel is a panel which basically converts solar energy into electric energy with the
help of photovoltaic material. There are different types of solar panel available in the
market but for our project we will use 12 volt and 500-800 mA rating solar panel.
Solar panel refers to a panel designed to absorb the sun's rays as a source of energy for
generating electricity or heating. Solar panels are devices that convert light into
electricity. They are called "solar" panels because most of the time, the most powerful
source of light available is the Sun, called Sol by astronomers. Some scientists call them
photovoltaic which means, basically, "light-electricity." A solar panel is a collection of
solar cells. Lots of small solar cells spread over a large area can work together to provide
enough power to be useful.
The light that hits a cell, the more electricity it produces, so spacecraft are usually
designed with solar panels that can always be pointed at the Sun even as the rest of the
body of the spacecraft moves around, much as a tank turret can be aimed independently
of where the tank is going.
Fig. 9. Solar Panel
Solar panel refers to a panel designed to absorb the sun's rays as a source of energy for
generating electricity or heating. A photovoltaic (in short PV) module is a packaged,
connected assembly of typically 6×10 solar cells. Solar Photovoltaic panels constitute the
solar array of a photovoltaic system that generates and supplies solar electricity in
commercial and residential applications. Each module is rated by its DC output power

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under standard test conditions, and typically ranges from 100 to 365 watts. The efficiency
of a module determines the area of a module given the same rated output an 8% efficient
230 watt module will have twice the area of a 16% efficient 230 watt module. There are a
few solar panels available that are exceeding 19% efficiency. A single solar module can
produce only a limited amount of power; most installations contain multiple modules. A
photovoltaic system typically includes a panel or an array of solar modules, a solar
inverter, and sometimes a battery and/or solar tracker and interconnection wiring.
Solar modules use light energy (photons) from the sun to generate electricity through the
photovoltaic effect. The majority of modules use wafer-based crystalline silicon cells or
thin-film cells based on cadmium telluride or silicon. The structural (load carrying)
member of a module can either be the top layer or the back layer. Cells must also be
protected from mechanical damage and moisture. Most solar modules are rigid, but semi-
flexible ones are available, based on thin-film cells.
Electrical connections are made in series to achieve a desired output voltage and/or in
parallel to provide a desired current capability. The conducting wires that take the current
off the modules may contain silver, copper or other non-magnetic conductive. The cells
must be connected electrically to one another and to the rest of the system.
Externally, popular terrestrial usage photovoltaic modules use MC3 (older) or MC4
connectors to facilitate easy weatherproof connections to the rest of the system. Bypass
diodes may be incorporated or used externally, in case of partial module shading, to
maximize the output of module sections still illuminated. Some recent solar module
designs include concentrators in which light is focused by lenses or mirrors onto an array
of smaller cells. This enables the use of cells with a high cost per unit area (such as
gallium arsenide) in a cost-effective way.
4.1.3 Battery
Battery is used to store energy which will be further used in Peltier module. We will use
12 volt lead acid rechargeable having 6.8 amp rating.
The storage battery or secondary battery is such battery where electrical energy can
be stored as chemical energy and this chemical energy is then converted to electrical
energy as when required. The conversion of electrical energy into chemical energy by
applying external electrical source is known as charging of battery. Whereas conversion
of chemical energy into electrical energy for supplying the external load is known as
discharging of secondary battery. During charging of battery, current is passed through it
which causes some chemical changes inside the battery.

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This chemical change absorbs energy during their formation. When the battery is
connected to the external load, the chemical changes take place in reverse direction,
during which the absorbed energy is released as electrical energy and supplied to the
load. Now we will try to understand principle working of lead acid battery and for that
we will first discuss about lead acid battery which is very commonly used as storage
battery or secondary battery.
The main active materials required to construct a lead-acid battery are
 Lead peroxide (PbO2)
 Sponge lead (Pb)
 Dilute sulfuric acid (H2SO4)
Lead Peroxide (PbO2): The positive plate is made of lead peroxide. This is dark brown,
hard and brittle substance.
Sponge Lead (Pb): The negative plate is made of pure lead in soft sponge condition.
Dilute Sulfuric Acid (H2SO4): Dilute sulfuric acid used for lead acid battery has ration of
water: acid = 3:1. The lead acid storage battery is formed by dipping lead peroxide plate
and sponge lead plate in dilute sulfuric acid. A load is connected externally between these
plates. In diluted sulfuric acid the molecules of the acid split into positive hydrogen ions
(H+
) and negative sulfate ions (SO4
− −
). The hydrogen ions when reach at PbO2 plate,
they receive electrons from it and become hydrogen atom which again attack PbO2 and
form PbO and H2O (water). This PbO reacts with H2 SO4 and forms PbSO4 and H2O
(water).
Ions are moving freely in the solution so some of them will reach to pure Pb plate where
they give their extra electrons and become radical SO4. As the radical SO4 cannot exist
alone it will attack Pb and will form PbSO4. As H+
ions take electrons from PbO2 plate
and SO4
− −
ions give electrons to Pb plate, there would be an inequality of electrons
between these two plates. Hence there would be a flow of current through the external
load between these plates for balancing this inequality of electrons. This process is called

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discharging of lead acid battery . The lead sulfate (PbSO4) is whitish in color. During
discharging,
 Both of the plates are covered with PbSO4.
 Specific gravity of sulfuric acid solution falls due to formation of water during
reaction at PbO2 plate.
 As a result, the rate of reaction falls which implies the potential difference
between the plates decreases during discharging process.
Now we will disconnect the load and connect PbSO4 covered PbO2 plate with positive
terminal of an external DC source and PbO2 covered Pb plate with negative terminal of
that DC source. During discharging, the density of sulfuric acid falls but there still
sulfuric acid exists in the solution.
This sulfuric acid also remains as H+
and SO4
− −
ions in the solution. Hydrogen ions
being positively charged, move to the electrode (cathode) connected with negative
terminal of the DC source. Here each H+
ion takes one electron from that and becomes
hydrogen atom. These hydrogen atoms then attack PbSO4 and form lead and sulfuric
acid.
SO4
− −
Ions (anions) move towards the electrode (anode) connected with positive terminal of DC
source where they will give up their extra electrons and become radical SO4. This radical
SO4 cannot exist alone hence reacts with PbSO4 of anode and forms lead peroxide (PbO2)
and sulfuric acid (H2SO4).
Hence by charging the lead acid storage battery cell,
 Lead sulfate anode gets converted into lead peroxide.
 Lead sulfate of cathode is converted to pure lead.
 Terminal; potential of the cell increases.
 Specific gravity of sulfuric acid increases.
4.1.4 DPDT Switch
A Double Pole Double Throw (DPDT) switch is a switch that has 2 inputs and 4 outputs;
each input has 2 corresponding outputs that it can connect to. Each of the terminals of a
double pole double switch can either be in 1 of 2 positions. This makes the double pole

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double throw switch a very versatile switch. With 2 inputs, it can connect to 4 different
outputs. It can reroute a circuit into 2 different modes of operation.
A Double Pole Double Throw Switch is actually two single pole double throw (SPDT)
switches.
 10 Amp rating
Fig. 10. Double Pole Double Throw (DPDT) Switch
4.1.5 Alluminium Sheet
However, aluminum is an excellent heat conductor so care would have to be taken to
insulate the container. So the container in which we keep water is made of aluminium.
4.1.6 Heat Sink with Cooling Fan
regulation of the device's temperature at optimal levels. In computers, heat sinks are used
to cool central processing units or graphics processors. Heat sinks are used with high-
power semiconductor devices such as power transistors and optoelectronics such as lasers
and light emitting diodes (LEDs), where the heat dissipation ability of the component
itself is insufficient to moderate its temperature. A heat sink is designed to maximize its
surface area in contact with the cooling medium surrounding it, such as the air. Air
velocity, choice of material, protrusion design and surface treatment are factors that affect
the performance of a heat sink.

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Fig. 11. Heat sink with cooling fan
Heat sink attachment methods and thermal interface materials also affect
the die temperature of the integrated circuit. Thermal adhesive or thermal grease improve
the heat sink's performance by filling air gaps between the heat sink and the heat
spreader on the device. A heat sink is usually made out of copper and/or aluminium.
Copper is used because it has many desirable properties for thermally efficient and
durable heat exchangers.
First and foremost, copper is an excellent conductor of heat. This means that copper's
high thermal conductivity allows heat to pass through it quickly. Aluminum is used in
applications where weight is a big concern.
4.1.2 4.1.7 MDF Board, Machine Screw, Glue Stick, PVC wire etc.
It supports the whole equipment.
4.1.8 Diode
The 1N4001 series (or 1N4000 series) is a family of popular 1A (ampere) general-
purpose silicon rectifier diodes commonly used in AC adapters for common household
appliances. Blocking voltage varies from 50 to 1000 volts. This diode series is available
in DO-41 axial package; SMA and MELF surface mount packages. The 1N5400 series is
a similarly popular series for higher-current 3A applications. These diodes are typically
available in the larger DO-201AD axial package to dissipate heat better.
In 4007 Features:
 Diffused Junction
 High Current Capability and Low Forward Voltage Drop
 Surge Overload Rating to 30A Peak

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 Low Reverse Leakage Current
 Lead Free Finish
Fig. 12. Diode IN4007
4.1.9 PCB
A printed circuit board (PCB) mechanically supports and electrically connects electronic
components using conductive tracks, pads and other features etched from copper
sheets laminated onto a non-conductive substrate.
PCBs can be single sided (one copper layer), double sided (two copper layers) or multi-
layer (outer and inner layers). Conductors on different layers are connected with vias.
Multi-layer PCBs allow for much higher component density.
FR-4 glass epoxy is the primary insulating substrate. A basic building block of the PCB is
an FR-4 panel with a thin layer of copper foil laminated to one or both sides. In multi-
layer boards multiple layers of material are laminated together.
Printed circuit boards are used in all but the simplest electronic products. Alternatives to
PCBs include wire wrap and point-to-point construction. PCBs require the additional
design effort to lay out the circuit, but manufacturing and assembly can be automated.
Manufacturing circuits with PCBs is cheaper and faster than with other wiring methods
as components are mounted and wired with one single part.
Fig. 13. PCB
4.1.10 Power Supply
12V–1 Amp rating for battery charging

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4.1.11 Rectifier
Rectifier is a device which converts the A.C. to Direct current. Rectifier is used when we
apply A.C. on place of D.C. So there is need to convert the A.C. to D.C.
Rectifier

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Design Specification
May 1, 2017
Anand Kumar
[ME/13/710]

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Approved By
Approvals should be obtained from faculty/ HOD
Faculty comments :
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
______
Faculty Name: Faculty Signature
_____________________________ _________________________
Project Coordinator Project Coordinator Signature
_____________________________ _________________________

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1 Introduction
1.1 Purpose
1.2 Project Scope
medicines
e) Desert Areas.
Air conditioning systems are mainly for the occupant’s health and comfort. They are often
called comfort air conditioning systems.

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1.3 References
Wien New York, 2007
107.
No.3, pp. 1233- 1245, February 2004.
Preventive Detection of Water Condensation”, Sensors and Actuators B 26-27
(1995) Pp. 303-307.

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2 System Overview
Thermoelectric cooling uses the Peltier effect to create a heat flux between the junctions
of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump is
a solid-state active heat pump which transfers heat from one side of the device to the
other, with consumption of electrical energy, depending on the direction of the current.
Such an instrument is also called a Peltier device, Peltier heat pump, solid state
refrigerator, or thermoelectric cooler (TEC). They can be used either for heating or for
cooling (refrigeration), although in practice the main application is cooling. It can also be
used as a temperature controller that either heats or cools.
This technology is far less commonly applied to refrigeration than vapor-compression
refrigeration. The main advantages of a Peltier cooler (compared to a vapor-compression
refrigerator) are its lack of moving parts or circulating liquid, near-infinite life and
invulnerability to potential leaks, and its small size and flexible shape (form factor). Its
main disadvantage is high cost and poor power efficiency. Many researchers and
companies are trying to develop Peltier coolers that are both cheap and efficient.
A Peltier cooler can also be used as a thermoelectric generator. When operated as a
cooler, a voltage is applied across the device, and as a result, a difference in temperature
will build up between the two sides. When operated as a generator, one side of the device
is heated to a temperature greater than the other side, and as a result, a difference in
voltage will build up between the two sides (the Seebeck effect). However, a well
designed Peltier cooler will be a mediocre thermoelectric generator and vice-versa, due to
different design and packaging requirements.
2.1 Photovoltaic Cell
A solar cell, or photovoltaic cell (PV), is a device that converts light into electric current
using the photoelectric effect. The first solar cell was constructed by Charles Fritts in the
1880s. In 1931 a German engineer, Dr Bruno Lange, developed a photocell using silver
selenide in place of copper oxide. Following the work of Russell Ohl in the 1940s,
researchers Gerald Pearson, Calvin Fuller and Daryl Chapin created the silicon solar cell
in 1954. These early solar cells cost 286 USD/watt and reached efficiencies of 4.5–6%.
By 2012 available efficiencies exceed 20% and the maximum efficiency of research
photovoltaics is over 40%.
Photovoltaics (PV) is a method of generating electrical power by converting solar
radiation into direct current electricity using semiconductors that exhibit the photovoltaic
effect. Photovoltaic power generation employs solar panels composed of a number of
solar cells containing a photovoltaic material. Solar photovoltaics power generation has
long been seen as a clean sustainable energy technology which draws upon the planet’s

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most plentiful and widely distributed renewable energy source the sun. It is well proven,
as photovoltaic systems have now been used for fifty years in specialised applications,
and grid-connected systems have been in use for over twenty years.
2.2 Peltier Effect
The Peltier effect is the presence of heating or cooling at an electrified junction of two
different conductors and is named after French physicist Jean Charles Athanase Peltier,
who discovered it in 1834. When a current is made to flow through a junction between
two conductors, A and B, heat may be generated or removed at the junction. The Peltier
heat generated at the junction per unit time, Ǭ, is equal to Ǭ = (∏A - ∏B) I
Where, ∏A (∏B) is the Peltier coefficient of the conductor A (B) (from A to B) and I is the
electric current. The total heat generated is not determined by the Peltier effect alone, as it
may also be influenced by Joule heating and thermal gradient effects.
The Peltier coefficients represent how much heat is carried per unit charge. Since charge
current must be continuous across a junction, the associated heat flow will develop a
discontinuity if ∏A and ∏B are different. The Peltier effect can be considered as the back-
action counterpart to the Seebeck effect: if a simple thermoelectric circuit is closed then
the Seebeck effect will drive a current, which in turn (via the Peltier effect) will always
transfer heat from the hot to the cold junction. The close relationship between Peltier and
Seebeck effects can be seen in the direct connection between their coefficients: ∏ = TS
A typical Peltier heat pump device involves multiple junctions in series, through which a
current is driven. Some of the junctions lose heat due to the Peltier effect, while others
gain heat. Thermoelectric heat pumps exploit this phenomenon, as do thermoelectric
cooling devices found in refrigerators.

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3 Development Methods
Before making decisions on which components to use for the box, theory had to be
reviewed and some preliminary calculations performed.
3.1 Passive Heat Load
The passive heat load for the unit was first calculated based upon a 25cm x 25cm x 25cm
interior volume. Two inches of polystyrene insulated was assumed (k=0.027w/mK).
Also included were a rubber seal on the door which was 50 cm2 in area.
x
T
k
x
T
kq rubberinstot






(5)
Where: qtot is the heat transfer in watts, kins is the resistance to heat transfer, and krubber is
0.014w/mK
ΔT is assumed to be 20 °C and Δx is 0.50m.
This gives a qtot of 10 W.
3.2 Active Heat Load
The active heat load is the equivalent of the cooling power that the unit will need to
provide when the sample at room temperature is placed in the container. It was decided
that one kilogram of water at room temperature would be the test sample for which all
calibration and calculations would be made. The time to cool this load from 25 °C to 5
°C was determined to be 1 hour, or 3600 seconds. Based on these values:
TmcQ p 
(6)
If the Cp of water is 4.14 KJ/kg*K, then Q = 82800J and dividing by 3600s to get power
(W), Qdot = 23 W for the active heat load. Therefore, the total load is 23 + 11 W = 34 W
of power required. This assumes that there is no thermal resistance between the sample
and the air in the unit. This may be an incorrect assumption but it does overestimate the
cooling load.
3.3 Thermoelectric cooling module
Assume that the active cooling load will be 10W due to the relatively slow rate of heat
transfer which will occur from the water. If the cooling load is rounded up to 35W will
give a power reserve of 15 W. Note that these estimations are best guesses of worst case
scenarios, testing should yield more reasonable results. It is impossible to directly
calculate which TEC and heatsink combination will meet heat load requirements. The
reason for this is that the choice of TEC and heatsink has the effect of changing the
required heat dissipation on the hot side of the TEC. Several successive iterations were

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required to determine a combination of TEC and heatsink which would meet our needs.
Following is the final calculation which should be successful. It has been determined
from previous iterations that a heat sink with a thermal resistance of less than 0.2 °C/W
will be required. Given our dimension restrictions (the size of the box), we went to
thermaflow.com which is a reputable supplier of various types and sizes of heatsinks.
From these restrictions it was determined that there are only 2 heatsinks which will meet
our needs. The specifications for E3107 follow with an extruded length of 150mm.
Fig. 14. Thermoelectric Module
3.4 Heat Sink
regulation of the device's temperature at optimal levels. In computers, heat sinks are used
to cool central processing units or graphics processors. Heat sinks are used with high-
power semiconductor devices such as power transistors and optoelectronics such as lasers
and light emitting diodes (LEDs), where the heat dissipation ability of the component
itself is insufficient to moderate its temperature. A heat sink is designed to maximize its
surface area in contact with the cooling medium surrounding it, such as the air. Air
velocity, choice of material, protrusion design and surface treatment are factors that affect
the performance of a heat sink.
Fig. 15. Heat Sink Profile

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Fig. 16. Heat Sink Performance Graphs
Examination of the chart shows that at 3m/s air flow velocity the thermal resistance of the
heatsink will be 0.17 °C/W. Note that this required airflow and the associated pressure
drop will need to be accounted for when the proper fan is selected.
3.5 Heat Load Required to be Dissipated by Heat Sink
Assume the Peltier, module is running at 12V which is fixed by power supply. This will
draw 6 Amps of currents. The following Vin vs. I graph1
shows a normal operating range
of the TEC. This value will be proved.
Fig. 17. Thermoelectric Module Performance

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The power consumed by the TEC is assumed in the worst case scenario to be added to the
heat on the hot side.
2
orsafetyfactsamplepassive
TEChot
QQQ
Pq


(7)
Division by two denotes that we have two TEC’s, two hot side heat sinks and two cold
side heat sinks to improve system efficiency. Therefore, qtot= 107W. This is the
maximum heat load to the hot side of each TEC and therefore each of the heat sinks.
3.6 Maximum Temperature Rise on Hot Side of TEC
Max temp rise = 107W x 0.17 °C/W = 18.2 °C
The ΔT over the TEC is 25 – 5 +18.2 (°C) = 38.2 °C, where 25 is the ambient temperature
on the hot side, 5 is inside desired temperature and 18 is the added heat load. The
following table will show that the operating point for heat removal of 18W (for each
TEC) and a ΔT of 38°C only requires a current draw of 4.5 Amps.
Fig. 18. Thermoelectric Performance Graph

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4 Detailed System Design
After considering the three main design criteria, (cooling methods, geometry and
materials) a final design was chosen. The final design configuration chosen by the team is
a box configuration using one large thermoelectric module having a total active heat load
of 15 watts. The thermoelectric module will be controlled by a proportional integral
derivative (PID) controller. A temperature display on the outside of the box will give the
user the ability to see the current absolute temperature of the controlled temperature
environment. The temperature will be set by the user via an adjustable dial with an
intuitive interface.
Power to thermoelectric modules will be delivered by a DC power unit. A temperature
sensor inside the temperature controlled environment will send a feedback signal to the
PID controller. The PID controller will then compare the feedback signal to the
temperature set by the user. If there is a discrepancy, the PID controller will adjust the
power to the thermoelectric modules until the feedback signal equals the set temperature.
Fans will be used to stir up the inside air of the temperature controlled environment and
provide airflow over the aluminum heat sinks. This will aid the thermoelectric modules to
operate more proficiently and ensure a uniform temperature distribution within the box.
The temperature controlled environment will be well insulated and placed on a framework
within a larger box. This larger box will encapsulate the PID controller, DC power unit,
temperature display, temperature dial, and all necessary circuitry. A door will be
constructed that will allow for experiments to be placed within the temperature controlled
environment. The door will have a rubber sealing and a magnetic clasp that will keep the
door closed when shut. The door will also be mounted on the top of the unit. This will be
an inconvenience with respect to access. However, by mounting the door on the top of the
unit, a more effective seal with the unit will be possible. The improvement of efficiency
should outweigh the inconvenience of accessibility.
4.1 Construction
Construction of the thermoelectric cooler is primarily divided up into four main sections
as follows:
 Exterior structure of the cooler
 Interior cooler Chamber
 Thermoelectric cooler assemblies with heat sinks
 Power, sensors and control
Each of these categories presents a different type of construction challenge. The exterior
physical structure will be largely composed of welded frames and formed sheet metal.
The interior structure will be fabricated out of fiberglass formed over a Styrofoam mold.

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The thermoelectric modules coupled with the heat sinks will require precision machining
work to fabricate and attach the heat sinks and modules together. Finally, the power,
sensors and control components will be mostly electronics.
4.1.1 Exterior Physical Structure
The main functions of the exterior structure are to house the components, provide
structural integrity and give a professional appearance. The structure will be fabricated by
welding together a rectangular box of square tubing. Attached to this shell will be a large,
formed sheet metal cover. The cover will provide some structural integrity, however the
welded frame will be more than adequate in this regard. The real purpose of the cover is
to give a clean, professional look to the finished product. The cover will be bolted onto
the frame.
4.1.2 Interior Cooler Chamber
The interior of the cooler will house the volume to be cooled. Therefore the material used
to construct this part must have the thermal property to resist heat flow. The interior must
also be able to be formed into geometries not easily achieved without complex cuts and
joints.
4.1.3 Thermoelectric Cooler Assemblies
The thermoelectric modules used in our design are approximately 4 millimeters thick. The
wall of the cooler with the insulation installed is about fifty-five millimeters thick. In
order to have a rapid rate of heat transfer between interior and exterior, an aluminum
spacer block will need to be machined to fit between the heat sinks and the thermoelectric
modules. Affixed to this spacer block on each end will be the heat sinks. A radial flow fan
on both the inside and outside heat sinks creates a forced convection flow over the heat
sinks. Between all mated surfaces through which heat transfer occurs thermal transfer
compound is required to be applied. Otherwise known as thermal grease, this substance
increases the efficiency of heat transfer.
4.1.4 Power, Sensors and Control
Power for the entire device will be provided through an AC to DC power supply. This
unit will plug into a standard 60 Hz, 120V wall socket. The approximate power
requirement to be supplied by the unit is 350 Watts. Sensing of temperature is a critical
element of the device. Resistance temperature detectors will be used to detect temperature
inside the cooling volume as well as outside. They will also be employed to monitor the
temperature at the hot side of the thermoelectric. Should the temperature at this location
rise above a critical value, the device would shut off to protect the components.

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5 Design Calculations
5.1 Annual Solar Output of Panel
The global formula to estimate the electricity generated in output of a photovoltaic system
is:
E = A * r *H * PR
E = Energy (kWh) A = Total solar panel Area (m²) r = solar panel yield (%) H = Annual
average solar radiation on tilted panels (shadings not included) PR = Performance ratio,
coefficient for losses (range between 0.5 and 0.9, default value = 0.75)
R is the yield of the solar panel given by the ratio: electrical power (in kWp) of one solar
panel divided by the area of one panel Example: the solar panel yield of a PV module of
250 W with an area of 1.48 m² is 16.8% PR : PR (Performance Ratio) is a very important
value to evaluate the quality of a photovoltaic installation because it gives the
performance of the installation independently of the orientation, inclination of the panel.
It includes all losses.
Selecting default value as 0.75
5.2 Peltier Module Heat Sink Calculations
With the increase in heat dissipation from electronics devices and the reduction in overall
form factors, thermal management becomes a more a more important element of
electronic product design. Heat sinks are devices that enhance heat dissipation from a hot
surface, usually the case of a heat generating component, to a cooler ambient, usually air.
For the following discussions, air is assumed to be the cooling fluid. In most situations,
heat transfer across the interface between the solid surface and the coolant air is the least
efficient within the system, and the solid-air interface represents the greatest barrier for
heat dissipation. A heat sink lowers this barrier mainly by increasing the surface area that
is in direct contact with the coolant. This allows more heat to be dissipated and/or lowers
the device operating temperature. The primary purpose of a heat sink is to maintain the
device temperature below the maximum allowable temperature specified by the device
manufacturers.
Before discussing the heat sink selection process, it is necessary to define common terms
and establish the concept of a thermal circuit. Notations and definitions of the terms are as
follows:
Q: Total power or rate of heat dissipation in W, represent the rate of heat dissipated by the
electronic component during operation. For the purpose of selecting a heat sink, the
maximum operating power dissipation issued. Tj: maximum junction temperature of the

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device in °C. Allowable Tj values range from 115°C in typical microelectronics
applications to as high as 180°C for some electronic control devices. In special and
military applications, 65°C to 80°Care not uncommon. Tc: case temperature of the device
in °C. Since the case temperature of a device depends on the location of measurement, it
usually represents the maximum local temperature of the case. Ts: sink temperature in °C.
Again, this represents the maximum temperature of a heat sink at the location closest to
the device. Ta: ambient air temperature in °C.
Using temperatures and the rate of heat dissipation, a quantitative measure of heat transfer
efficiency across two locations of a thermal component can be expressed in terms of
thermal resistance R, defined as:
R = ∆T/Q
Were T is the temperature difference between the two locations. The unit of thermal
resistance is in °C/W, indicating the temperature rise per unit rate of heat dissipation. This
thermal resistance is analogous to the electrical resistance Re, given by Ohm’s law:
Re =∆V/I
With V being the voltage difference and I the current
The thermal resistance between the junction and the case of a device is defined as:
Rjc = (Tjc)/Q = (Tj- Tc)/Q
This resistance is specified by the device manufacturer. Although the Rjc value of a give
device depends on how and where the cooling mechanism is employed over the package,
it is usually given as a constant value. It is also accepted that Rjc is beyond the user’s
ability to alter or control. Similarly, case-to-sink and sink-to-ambient resistances are
defined as:
Rcs = (∆Tcs)/Q = (Tc- Ts)/Q
Rsa = (∆Tsa)/Q = (Ts- Ta)/Q
Here, Rcs represents the thermal resistance across the interface between the case and the
heat sink and is often called the interface resistance. This value can be improved
substantially depending on the quality of mating surface finish and/or the choice of
interface material. Rsa is heat sink thermal resistance.
To begin the heat sink selection, the first step is to determine the heat sink thermal
resistance required to satisfy the thermal criteria of the component. By rearranging the
previous equation, the heat sink resistance can be easily obtained as:
Rsa = ((Ts – Ta)/Q) – Rjc- Rcs
In this expression, Tj, Q and Rjc are provided by the device manufacturer, and Ta and

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Area of aluminium enclose-80 cm*cm*cm
Voltage-12 V
Time- 25 min
Temperature Difference-10 Degree C

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5 CONCLUSION
provide cold water for residential, commercial, and industrial applications. These
technologies displace the need to use electricity or natural gas. Today, Countries
policies to expand this fast growing, job producing sector
 From the above results we can conclude that the reliability of the Peltier
module available in India is less with unsatisfactory level of cooling.
 Thus more research is required in the cooling module design with high quality
Peltier modules to be made available from U.S or Europe.
 If such changes are made than the rate of satisfactory results will surely
increase with reliability.
 The general system is simple to design yet performance of the entire system is yet
to be realized.
 Due to certain abnormalities we were unable to successfully interface the
regulator circuit with the TEC and the solar panel.
 Furthermore, other factors like shading and effective mounting also hinder the
performance of the PV system.

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6 REFERENCES
Wien New York, 2007
107.
No.3, pp. 1233- 1245, February 2004.
 Preventive Detection of Water Condensation”, Sensors and Actuators B 26-27
(1995) Pp. 303-307.
 Field Rl. Photovoltaic / Thermoelectric Refrigerator for Medicine Storage for
Developing Countries. Sol Energy 1980; 25(5):4457.

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7 CHECKLIST
This checklist is to be duly completed by the student and verified by the Faculty Project
Coordinator.
1. Is the report properly hard/ spiral bound? Yes / No
2. Is the Cover page in proper format? Yes / No
3. Is the Title page (Inner cover page) in proper format? Yes / No
4. (a) Is the Certificate from the Company in proper format?
(b) Has it been signed by the Manager?
Yes / No
Yes / No
5. (a) Is the Acknowledgement from the Student in proper
format?
(b) Has it been signed by the Student?
Yes / No
6. Does the Table of Contents include page numbers?
(i). Are the Pages numbered properly?
(ii). Are the Figures numbered properly?
(iii). Are the Tables numbered properly?
(iv). Are the Captions for the Figures and Tables proper?
(v). Are the Appendices numbered properly?
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
Yes / No
7. Is the conclusion of the Report based on discussion of the
work?
Yes / No
8. Are References or Bibliography given in the Report?
Have the References been cited inside the text of the Report?
Is the citation of References in proper format?
Yes / No
Yes / No
Yes / No

Project Report
SBIT Page 54
9. A Compact Disk (CD) containing the softcopy of the Final
Report (preferably in PDF format) and a Final Project
Presentation in MS power point only has been placed in a
protective jacket securely fastened to the inner back cover of
the Final Report. Write the name and Roll No on the CD.
Yes / No
Declaration by Student
I certify that I have properly verified all the items in the checklist and
ensure that the report is in proper format as specified in the course handout.
Name:
Place:
Date:
Signature of the Student:
Verification by Faculty Project Coordinator
I have duly verified all the items in the checklist and ensured that the report
is in proper format.
Name:
Place:
Date:
Signature of the Project Coordinator:

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