Final Undergrad Project in Mechanical Engineering

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A PROJECT REPORT
ON
THERMOELECTRIC COOLING SYSTEM
submitted in partial fulfillment of the requirement for the award of the degree of
BACHELOR OF TECHNOLOGY
(Department of Mechanical Engineering)
Submitted by
RAVI SHARMA (130970104048)
RAJESH NAKOTI (130970104046)
RAJESH SEMWAL (130970104047)
TARUN BHIDOLA (130970104066)
RAHUL SINGH (130970104043)
KRITIKA (130970104026)
Under the Guidance of
MR. AMIT KUMAR
(Assistant Professor)
in
DEPARTMENT OF MECHANICAL ENGINEERING
THDC INSTITUTE OF HYDROPOWER ENGINEERING & TECHNOLOGY
TEHRI, UTTARAKHAND

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ACKNOWLEDGEMENT
We take this opportunity to thank all the teachers of Mechanical Engineering
Department for allowing us to work on such an interesting & informative topic.
We are highly indebted to our class in-charge and project guide Mr. Amit Kumar
Sir for his guidance & words of wisdom. He always showed us the right direction
during the course of this project work. We are duly thankful to him to referring us
to sites like science direct, open pdf & providing many research papers which had
some research work.
Success in such comprehensive report can’t be achieved single handed. It is the
team effort that sail the ship to the coast. So I would like to express my sincere
thanks to HOD of mechanical department Mr. PraveenKumar Sir.
We worked as a team and saw ups and downs which are part of any project work.
But in the end it was their Guidance and my team work which made this project
possible. Last but not the least we would also like to thank all our teachers &
friends for their constructive criticism given in right spirit.
RAVI SHARMA (130970104048)
RAJESHNAKOTI (130970104046)
RAJESHSEMWAL (130970104047)
TARUN BHIDOLA (130970104066)
RAHUL SINGH (130970104043)
KRITIKA (130970104026)

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Certificate Of Mentor
This is to certify that the work which is being presented in entitled
“THERMOELECTRIC COOLING SYSTEM” in partial fulfillment
of the requirement for the award of the degree of Bachelor of
Technology and submitted in the Department of Mechanical
Engineering of THDC Institute of Hydropower Engineering and
Technology, Tehri , is an authentic record of our own work carried
out under the supervision of Amit Kumar, Assistant Professor,
Department of Mechanical Engineering, THDC Institute of
Hydropower Engineering and Technology, Tehri under
Uttarakhand Technical University, Dehradun.
The matter presented in this report has not been submitted by us
anywhere for the award of any other degree of this or any other
institute.
RAVI SHARMA (130970104048)
RAJESH NAKOTI (130970104046)
RAJESH SEMWAL (130970104047)
TARUN BHIDOLA (130970104066)
RAHUL SINGH (130970104043)
KRITIKA (130970104026)
This is to certify that the above statement made by the candidate is
correct to the best of our knowledge.
Date: (Amit Kumar)
Supervisor

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TABLE OF CONTENT
CONTENT PAGE NO
1. Abstract 6
2. Introduction 7
3. Project objective 8
4. Literature review 9
5. Thermoelectric air conditioning system 11
6. Thermoelectricity 13
7. Basic principle 16
8. Peltier Effect 17
9. Seeback effect 20
10. Thomson effect 22
11. Thermoelectric module 24
12. Thermoelectric module selection 27
13. Installation of TEM 29
14. Parameters of TEM 38
15. Thermoelectric materials 44
16. Application for thermoelectric coolers 49
17. Conclusion 52
18. References 53

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LIST OF FIGURE
Figures Page
No.
Figure 1:N type doping 14
Figure 2:P type doping 15
Figure 3: Power supply in P-Type Semiconductor 16
Figure 4: Current Flow in P-N Junction 17
Figure 5:Peltier effect 17
Figure 6: P-N Junction Arrangement 19
Figure7:Seebeck effect 20
Figure 8: Thermoelectric Module 24
Figure 9: A typical single stage thermoelectric module 25
Figure 10: Cross section of TE Module 26
Figure 11: A Classic TE Module Assembly 26
Figure 12: Total assembly of TEM 29
Figure 13: Clamping of TE module 32
Figure 14:TE Module Installation Using the Clamping Method 34
Figure 15: A Cross sectional View of Thermoelectric Module 38
Figure 16: Forced convection heat sink system 41
Figure 17: Thermal Schematic diagram 41

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ABSTRACT
The global increasing demand for refrigeration in field of refrigeration air-conditioning, food
preservation, vaccine storage, medical services, and cooling of electronic devices, led to
production of more electricity and consequently more release of CO2 all over the world which it
is contributing factor of global warming on climate change. Thermoelectric refrigeration is new
alternative because it can convert electricity into useful cooling, is expected to play an important
role in meeting today energy challenges. Therefore, thermoelectric refrigeration is greatly
needed, particularly for developing countries where long life and low maintenance are needed.
The objectives of this study are design and develop a working thermoelectric refrigerator interior
cooling volume of 5L that utilizes the Peltier effect to refrigerate and maintain a selected
temperature from 5 °C to 25 °C. The design requirements are to cool this volume to temperature
within a time period of 6 hrs and provide retention of at least next half an hour. The design
requirement, options available and the final design of Thermoelectric refrigerator for application
are presented.
In present scenario, HVAC system (commonly used in the air conditioners) is very efficient and
reliable but it has some demerits. It has been observed during the last two decades that the O3
layer is slowly destroyed because of the refrigerant (CFC and HFC) used for the refrigeration
and air- conditioning purposes. The common refrigerant used is HFC’s which are leaked and
slowly ascend into the atmosphere. When they reach to O3 layer they act on O3 molecules and
the layer of O3 is destroyed. A single molecule of HFC can destroy thousands of O3 molecules
and that's why it has created a threat for the not only to maintain earth eco system stable but also
to existence of earth. Even the percentage of HFCs are emitted into the atmosphere compared to
CO2 is negligible but its global warming effect is few thousand times of CO2. The effect of 100
gm of HFC can destroy 0.5 tons of O3 molecules. These HFCs once destroy O3 layer; it takes
hundreds of years to recover its thickness as it is formed by complex reactions. This is because as
HFCs comes in environment, they remain in atmosphere for 18 years. The capacity of HFCs to
increase in earth temperature 10% is contributed by HFC’s only. That leads to the emergence of
finding an alternative of the conventional HVAC system, i.e. thermo-electric cooling and heating
system.

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CHAPTER 1
INTRODUCTION
Conventional compressor run cooling devices have many drawbacks in relation to energy
efficiency and the use of CFC refrigerants. Both these factors indirectly point to the impending
scenario of global warming. As most of the electricity generation relies on the coal power plants,
which add greenhouse gases to the atmosphere is the major cause of global warming. Although
researches are going on, better alternatives for the CFC refrigerants is still on the hunt. So instead
of using conventional air conditioning systems, other products which can efficiently cool a
person are to be devised. By using other efficient cooling mechanisms we can save the electricity
bills and also control the greenhouse gases that are currently released into the atmosphere.
Although Thermoelectric (TE) property was discovered about two centuries ago, thermoelectric
devices have only been commercialized during recent years. The applications of TE vary from
small refrigerators and electronics package cooling to Avionic instrumentation illumination
control and thermal imaging cameras. Lately a dramatic increase in the applications of TE
coolers in the industry has been observed. It includes water chillier, cold plates, portable insulin
coolers, portable beverage containers and etc.
As conventional air conditioner is commonly available in the market, a TE cooling module
installed on it will be an easy and efficient way to cool a person. An effort to build a cooling
system was the main aim of this project. Sizing and designing of the cooling system was
performed and tested with a designed DC power supply. The conventional air conditioner
together with the cooling module can be termed as Thermoelectric Cooled Air Conditioner.

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CHAPTER 2
PROBLEM FORMULATION
PROJECTOBJECTIVE
The idea was to build an alternative for air conditioner and to provide cooling effect. The project
aims to design and build a miniature prototype of thermoelectric cooling system for a
conventional air conditioning provide cooling. The system was targeted as an air conditioner and
temperature of the cooled air should be lowered 20 degree Celsius from ambient temperature.
Secondary objective of the project includes design of a dc power supply through solar panels and
a temperature controller circuit.
SCOPE OF PROJECT
The project involves the development of a suitable cooling module designed with an air
conditioner 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.
The project scope involves the following elements:
1. Sizing and Designing of the air conditioning system
2. Selection of the TEM
3. Selection of Fans and Heat sinks
4. DC power supply design with temperature control.
5. Prototype Assembly and Fabrication.
6. Temperature measurements for testing.
7. Power supply testing and troubleshooting.

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PROPOSED APPROACHAND METHOD
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.
Figure 1: Block diagram of the thermoelectric cooled air conditioner

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PROJECTTASKS
This project was separated into five phases. The first phase was the preparation and research
phase. The second phase was design and selection of components. The third phase was the
fabrication and assembly of the prototype. The fourth phase was the testing, troubleshooting and
modification. The fifth and final phase was the report and presentation phase.
Phase 1 – The first phase of the project involved the project proposal, getting the approval of the
project proposal, drafting of the project plan and gathering of the information needed for the
project. A thorough literature review was also conducted to expand one’s knowledge.
Phase 2 – The second phase involved in-depth research on selection of TECs and heat sinks. A
Design for the cooling section was confirmed in this phase. Various calculations regarding the
selection of heat sinks, TEC and blower fan was made. The power supply circuit and temperature
controller circuit was confirmed and designed. Drawings for the electronic circuits with
ALTUIM design tool and mechanical designs with solid works were also made during this
phase.
Phase 3 – During this phase, all the purchased components were soldered onto the board. On the
other hand the Assembly of the TECs, heat sinks, fans, clips etc were done.
Phase 4 – This was the most challenging phase where by troubleshooting of the power supply
board was carried out. Different temperature readings and measurements were taken from the
refrigeration system prototype. Certain modifications were made on the prototype as well as on
the power supply circuitry.
Phase 5 – During this phase, more time was allocated to prepare for final year report and
oral/poster presentation as well as highlight areas of the project which will need further work. A
power point presentation was also done in preparation for the final presentation.
Thus the project task is completed into five phases. Lots of planning, preparation and hard work
was done in completion of project.

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CHAPTER 3
LITERATURE RIVEW (HISTORY)
Thermoelectric phenomenon was discovered nearly two hundred years ago. Since last sixty years
the practical applications from thermoelectric had been exploited.
The first breakthrough that would eventually be used to form the thermoelectric effect was
discovered in 1820. Several other breakthroughs in the field were discovered over the next few
decades but their relationship was not realized for a full 38 years. William Thomson in 2007
discovered that heat is absorbed or produced when current flows in material with a certain
temperature gradient and that the heat is proportional to both the electric current and the
temperature gradient. His publication linked all the discoveries from the preceding decades.
Thermoelectric coolers which is also known as thermoelectric module or Peltier cooler is
widely used in the market for several cooling applications. Use of TE modules often gives an
answer to many critical thermal management problems, where low to moderate amount of heat is
concerned.
Certain advantages of TE coolers are, it works electrically without any moving parts, and
thus it becomes maintenance free and silent. They are able to cool or heat within the same
module depending on the polarity of the applied DC power. Traditional refrigeration systems are
almost impossible to be manufactured without using chlorofluorocarbons or other chemicals that
harmful to the environment. TE devices do not use or generate gases of any kind. TE modules
are noted when there is a need to cool one specific component or area only.
Koetzsch and Madden (2009) examined on thermoelectric cooling versus conventional
cooling in industrial enclosures. Conventional cooling systems such as air conditioners and air-
to-water heat exchangers rely on chemical refrigerants or water to cool, or remove heat from,
enclosures. Besides that refrigerants, air conditioners use compressors, evaporators, condensers
and fans to provide cooling. For the operation of Air-to-water heat exchangers it must have a
connection with the facility’s chilled water system. On the other hand a TE cooler does not

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require any of the before mentioned things required by air conditioners and air-to-water heat
exchangers. Thus TE coolers provide effective cooling without refrigerants, water or other
components such as compressors and coils to effect. It only requires TE module, a fan and a
power supply. So studies have proven that TE coolers are very useful when used for cooling in
industrial enclosures.
Several studies related on TE coolers with regards to vehicles and are utilized well. They
can be integrated into several designs. Hyeung in (2007) have done a research on thermoelectric
device to control the temperature of car- seat surface. The device helped when the temperature is
warm in summer and cold in winter. Thermoelectric property was also implemented in pick up
refrigerated trucks. Studies based on thermoelectric cooling unit for thermostatic body on
refrigerated trucks were conducted by Bulat and Nekhoroshev (2003). In this study a comparison
between the thermoelectric cooling units with vapour-compression installations was also made,
where it showed that cost price of thermoelectric unit is four-five times cheaper than vapour-
compression cooling units. The cooling power obtained for TE cooling was same when
compared to compression cooling units.
These are excellent examples for spot cooling property of a TE module. Once such
prototype was made by Bartlett and Sukuse (2007) .They has built an air-conditioned cooling
helmet which used thermoelectric device. The product was designed to give comfort for the user.
The idea of cooling helmet was also discussed by Buist and Streitwieser (1988). The 12 volt
personal cooling system worked well to cool the head of a race driver. The 225 grams helmet
cooling system reduced 5 to 6 degree Celsius form ambient.
There are many TEC manufactures in the market and to facilitate the search, a few of them
provide downloadable software search facilities. One such software is provided by Laird
Technologies, which is an excellent tool for thermoelectric module simulation. It can be used for
the analysis and selection of TECs or TEMs. Selection of a TEC from various manufactures can
be tedious. Tan and Fok (2008) have conducted an analytical study on method of selecting a
TEC from different manufacturers before designing a cooling system. Their purpose of study
was to assist the designers to help on developing an optimised thermoelectric cooling system
design in minimum amount of time. The designers will be benefited from this study to
implement a cooling system with TEC.

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Many of the previous studies discussed above ensure that TEC is a reliable product to be
used in a refrigeration system for personal use. The author is confident that anyone who has a
keen interest to design TEC cooling system and if they are willing to trail certain methodology
and sizing this report will set as good example.

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CHAPTER 4
THERMOELECTRIC COOLING SYSTEM
To design a cooling system using thermoelectric cooler (TEC) one has to know the basics of
thermoelectric effect, thermoelectric cooling and thermoelectric materials. Thermoelectric effect
can be defined as the direct conversion of temperature difference to electric voltage and vice
versa. Thermoelectric effect covers three different identified affects namely, the Seeback effect,
Peltier effect and the Thomson effect
A thermoelectric device will create a voltage when there is temperature difference on each
side of the device. On the other hand when a voltage is applied to it, a temperature difference is
created. The temperature difference is also known as Peltier effect. Thus TEC operates by the
Peltier effect, which stimulates a difference in temperature when an electric current flows
through a junction of two dissimilar materials.
Figure 2: A Thermoelectric or Compressor less Refrigerator.

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A good thermoelectric cooling design is achieved using a TEC, which is solid state electrically
driven heat exchanger. This depends on the polarity of the applied voltage. When TEC is used
for cooling, it absorbs heat from the surface to be cooled and transfers the energy by conduction
to the finned or liquid heat exchanger, which ultimately dissipates the waste heat to the
surrounding ambient air by means of convection.
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 side against the
temperature gradient (from cold to hot), with consumption of electrical energy. Such an
instrument is also called a Peltier device, Peltier diode, cooling diode, Peltier heat pump, solid
state refrigerator, or thermoelectric cooler (TEC). Because heating can be achieved more easily
and economically by many other methods, Peltier devices are mostly used for cooling. However,
when a single device is to be used for both heating and cooling, a Peltier device may be
desirable. Simply connecting it to a DC voltage will cause one side to cool, while the other side
warms. The effectiveness of the pump at moving the heat away from the cold side is dependent
upon the amount of current provided and how well the heat can be removed from the hot side.
Peltier devices can also be used to generate electricity (thermo-generator) if the temperature
difference is maintained between the two sides.
WHAT IS IT?
Cooling is the process of pumping heat energy out of a chamber in order to reduce the
temperature of the chamber below that of the surrounding air. Thermoelectric conditioning uses a
principle called the "PELTIER" effect to pump heat electronically. The Peltier effect is named
after a French scientist who discovered it in 1834.
HOW DOES IT WORK?
In 1834 Jean Peltier noted that when an electrical current is applied across the junction of two
dissimilar metals, heat is removed from one of the metals and transferred to the other. This is the
basis of thermoelectric conditioner. Thermoelectric modules are constructed from a series of tiny

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metal cubes of dissimilar exotic metals which are physically bonded together and connected
electrically. When electrical current passes through the cube junctions, heat is transferred from
one metal to the other. Solid-state thermoelectric modules are capable of transferring large
quantities of heat when connected to a heat absorbing device on one side and a heat dissipating
device on the other. The Koolatron's internal aluminum cold plate fins absorb heat from the
contents, and the thermoelectric modules transfer it to heat dissipating fins under the control
panel. Here, a small fan helps to disperse the heat into the air. The system is totally
environmentally friendly and contains no hazardous gases, nor pipes nor coils and no
compressor. The only moving part is the small 12-volt fan. Thermoelectric modules are too
expensive for normal domestic and commercial applications which run only on regular
household current. They are ideally suited to recreational applications because they are
lightweight, compact, and insensitive to motion or tilting, have no moving parts, and can operate
directly from 12-volt batteries.
THERMOELECTRICITY
Thermoelectricity (thermo-electricity, abbreviated as TE) refers to a class of phenomena in
which a temperature difference creates an electric potential or an electric potential creates a
temperature difference. In modern technical usage, the term almost always refers collectively to
the Seeback effect, Peltier effect, and the Thomson effect. Analyzing the word thermoelectricity
by its etymological components, it might be taken to refer generically to all heat engines that are
used to generate electricity and all electrically powered heating devices, for which there is an
almost arbitrary number of conceivable techniques, but in practice such a broad use of the term is
seldom encountered.
In recent years, thermoelectricity has been increasingly used in applications like portable
refrigerators, beverage coolers, electronic component coolers, and metal alloy sorting devices.
One of the most commonly used materials for such applications is Bismuth telluride (Bi2Te3), a
chemical compound of bismuth and tellurium.

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Motivation for research
Currently there are two primary arenas in which thermoelectric devices can lend themselves to
increase energy efficiency and/or decrease pollutants: conversion of waste heat into usable
energy, and air conditioning.
Powergeneration(Thermo-generator)
In the transportation sector, although very common as a means of powering vehicles, internal
combustion engines are highly inefficient in energy use (using only 20-25% of the energy
generated during fuel combustion). Furthermore, the electricity requirement in vehicles is
increasing due to the demands of enhanced performance, on-board controls and creature
comforts (stability controls, telemetric, navigation systems, electronic braking, etc.). In order to
gain fuel efficiency, it may be possible to shift energy draw from the engine (in certain cases) to
the electrical load in the car, e.g. electrical power steering or electrical coolant pump operation.
Thermoelectric devices are thus being investigated to convert waste-heat into usable energy
using the Seeback Effect.
Currently, some power plants use a method known as cogeneration in which in addition to the
electrical energy generated, the heat produced during the process is used for alternative purposes.
Thermoelectric may find applications in such systems or in solar thermal energy generation.
AIR CONDITIONING
Thermoelectric devices applied to refrigeration and air conditioning using the Peltier effect could
reduce the emission of ozone-depleting refrigerants into the atmosphere. Hydro
chlorofluorocarbons (HCFCs) and chlorofluorocarbons (CFCs) are known ozone depleting
substances (ODSs); however, these chemicals have long been at the heart of refrigeration
technology. Recently, there has been legislation regulating the use of such chemicals for
refrigeration; current international legislation mandates caps on HCFC production and will
prohibit their production after 2020 in developed countries and 2030 in developing countries.
These mandates as well as consumers are leading to an increased effort in developing effective
thermoelectric conditioning units. Such units could reduce the use of such harmful chemicals and

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would operate more quietly (since they are solid state and do not require noisy compressors.)
Vapor compression air conditioners are still more efficient than Peltier air conditioners, but they
are larger, and require more maintenance.
BASIC PRINCIPLE
A semiconductor (called a pellet) is used because they can be optimized for pumping heat and
because the type of charge carriers within them can be chosen. The semiconductor in this
examples n-type (doped with electrons) therefore, the electrons move towards the positive end of
the battery. The semiconductor is soldered to two conductive materials, like copper. When the
voltage is applied heat is transported in the direction of current flow.
When a p-type semiconductor (doped with holes) is used instead, the holes move in a direction
opposite the current flow. The heat is also transported in a direction opposite the current flow
and in the direction of the holes. Essentially, the charge carriers dictate the direction of heat flow.
Figure 3: Power supply in P-Type Semiconductor
The most efficient configuration is where a p and n TE component is put electrically in series but
thermally in parallel. The device to the left is called a couple. One side is attached to a heat
source and the other a heat sink that converts the heat away. The side facing the heat source is
considered the cold side and the side facing the heat sink the hot side.

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Figure 4: Current Flow in P-N Junction
PELTIER EFFECT
The Peltier (pronounced /ˈpɛltyeɪ/) effect bears the name of Jean-Charles Peltier, a French
physicist who in 1834 discovered the calorific effect of an electrical current at the junction of
two different metals. When a current I is made to flow through the circuit, heat is evolved at the
upper junction (at T2), and absorbed at the lower junction (at T1). The Peltier heat absorbed by
the lower junction per unit time, Q̇ is equal to
𝐐̇ = 𝚷 𝒂𝒃 𝐈 = (𝚷 𝒂 − 𝚷 𝒃)𝐈
Where ∏ is the Peltier coefficient ΠAB of the entire thermocouple, and Πa and Πb are the
coefficients of each material. p-Type silicon typically has a positive Peltier coefficient (though
not above ~550 K), and n-type silicon is typically negative.
The Peltier coefficients represent how much heat current is carried per unit charge through a
given material. Since charge current must be continuous across a junction, the associated heat
flow will develop a discontinuity if Πa and Πb are different. This causes a non-zero divergence at
the junction and so heat must accumulate or deplete there, depending on the sign of the current.

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Another way to understand how this effect could cool a junction is to note that when electrons
flow from a region of high density to a region of low density, this "expansion" causes cooling (as
with an ideal gas).
You can create the Peltier effect with a battery, two pieces of copper wire and a piece of bismuth
or iron wire. Just connect the copper wires to the two poles of the battery, and then connect the
bismuth or iron wire between the two pieces of copper wire. The bismuth/iron and copper must
touch -- it is this junction that causes the Peltier effect.
The junction where current flows from copper to bismuth will get hot, and the junction where
current flows from bismuth to copper the junction will get cold. The maximum temperature drop
is about 40 F from the ambient temperature where the hot junction is located.
To create a Peltier cooler, the hot junction is placed outside the refrigerator, and the cold junction
is placed inside. Normally, you create a module containing many junctions to amplify the effect
in series.
An interesting consequence of this effect is that the direction of heat transfer is controlled by the
polarity of the current; reversing the polarity will change the direction of transfer and thus the
sign of the heat absorbed/evolved.
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. Peltier cooling is also called thermo-
electric cooling (TEC).
Figure 5: P-N Junction Arrangement

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Thermoelectric legs are thermally in parallel and electrically in series.
Thermoelectric junctions are generally only around 5–10% as efficient as the ideal refrigerator
(Carnot cycle), compared with 40–60% achieved by conventional compression cycle systems
(reverse Rankine systems using compression/expansion). Due to the relatively low efficiency,
thermoelectric cooling is generally only used in environments where the solid state nature (no
moving parts, maintenance-free) outweighs pure efficiency.
Peltier (thermoelectric) cooler performance is a function of ambient temperature, hot and cold
side heat exchanger (heat sink) performance, thermal load, Peltier module (thermopile)
geometry, and Peltier electrical parameters.
THERMOELECTRIC MODULE
Figure 6: Thermoelectric Modules
A standard module consists of any number of thermocouples connected in series and sandwiched
between two ceramic plates. By applying a current to the module one ceramic plate is heated
while the other is cooled. The direction of the current determines which plate is cooled. The
number and size of the thermocouples as well as the materials used in the manufacturing
determine the cooling capacity. Cooling capacity varies from fractions of Watts up to many
hundreds.
Different types of TEC modules are single stage, two stage, three stage, four stage, center hole
modules etc. Single stage will be suitable for a wide range of cooling applications with low to
high heat pumping capacities. A typical single stage is shown in Figure.

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Figure 7: A typical single stage thermoelectric module.
Thermoelectric modules are solid-state devices capable of generating electrical power from a
temperature gradient, known as the Seeback effect, or converting electrical energy into a
temperature gradient, known as the Peltier effect.
A typical thermoelectric module is composed of two ceramic substrates that serve as a housing
and electrical insulation for P-type and N-type (typically Bismuth Telluride) elements between
the substrates. Heat is absorbed at the cold junction by electrons as they pass from a low energy
level in the p-type element, to a higher energy level in the n-type element. At the hot junction,
energy is expelled to a thermal sink as electrons move from a high energy element to a lower
energy element. A module contains several P-N couples that are connected electrically in series
and thermally in parallel.
Figure 8: Cross section of TE Module

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Figure 9: A Classic TE Module Assembly
To assist the thermal designer in modeling thermoelectric coolers or Peltier modules, C&R
Technologies’ tool suite provides built in routines for modeling either standard Bismuth
Telluride coolers or modules manufactured from alternative semiconductor materials (in which
case the user must provide the Seeback coefficient, electrical resistivity, and thermal
conductivity). The family of TEC routines provides the designer the ability to model single stage
or multi-stage coolers, and calculate valuable sizing information regarding cooler performance.
Before starting to design a TEC cooling system the designer have to take note the following into
consideration.
1. Temperature to be maintained for the object that is to be cooled.
2. Heat to be removed from the cooled object.
3. Time required attaining the cooling after a DC power is applied.
4. Expected ambient temperature.
5. Space available for the module and hot side heat sink.
6. Expected temperature of hot side heat sink.
7. Power available for the TEC.
8. Controlling the temperature of the cooled object if necessary.

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CHAPTER 5
THERMOELECTRIC MODULE SELECTION
Selection of the proper TE Cooler for a specific application requires an evaluation of the total
system in which the cooler will be used. For most applications it should be possible to use one of
the standard module configurations while in certain cases a special design may be needed to
meet stringent electrical, mechanical, or other requirements. Although we encourage the use of a
standard device whenever possible, Ferrotec America specializes in the development and
manufacture of custom TE modules and we will be pleased to quote on unique devices that will
exactly meet your requirements.
The overall cooling system is dynamic in nature and system performance is a function of several
interrelated parameters. As a result, it usually is necessary to make a series of iterative
calculations to "zero-in" on the correct operating parameters.
Before starting the actual TE module selection process, the designer should be prepared to
answer the following questions:
1. At what temperature must the cooled object be maintained?
2. How much heat must be removed from the cooled object?
3. Is thermal response time important? If yes, how quickly must the cooled object change
temperature after DC power has been applied?
4. What is the expected ambient temperature? Will the ambient temperature change
significantly during system operation?
5. What is the extraneous heat input (heat leak) to the object as a result of conduction,
convection, and/or radiation?
6. How much space is available for the module and heat sink?
7. What power is available?
8. Does the temperature of the cooled object have to be controlled? If yes, to what
precision?

25. Page | 25
9. What is the expected approximate temperature of the heat sink during operation? Is it
possible that the heat sink temperature will change significantly due to ambient
fluctuations, etc.?
Each application obviously will have its own set of requirements that likely will vary in level of
importance. Based upon any critical requirements that cannot be altered, the designer's job will
be to select compatible components and operating parameters that ultimately will form an
efficient and reliable cooling system.
SPECIFICATION OF THERMOELECTRIC MODULE
TEC1-12706
Description
The 127 couples, 40 mm × 40 mm size single stage module is made of selected high performance
ingot to achieve superior cooling performance and greater delta T up to 70 °C, designed for
superior cooling and heating up to 100 ºC requirement. If higher operation or processing
temperature is required, please specify, we can design and manufacture the custom made module
according to your special requirements.
Features Application
● High effective cooling and efficiency.
● Food and beverage service refrigerator
● No moving parts, no noise, and solid-state
● Portable cooler box for cars
● Compact structure, small in size, light in weight
● Environmental friendly
● Temperature stabilizer
● Precise temperature control
● Photonic and medical systems

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PERFORMANCECHART
Th(℃) 27 50 Hot side temperature at environment: Dry air ,N2
DTmax 70 79 Temperature difference between hot and cold side of
module when cooling capacity is zero at cold side
Umax 16 17.2 Voltage applied to the module at DTmax
Imax 6.1 6.1 DC current through the module at DTmax
QCmax(Watts) 61.4 66.7 Cooling capacity at the cold side of the module at DT=0
℃
AC
resistance(ohms)
2 2.2 The module resistance tested under AC
Tolerance(%) 10 For thermal and electricity parameter
USE OF TE MODULE PERFORMANCEGRAPHS
Before beginning any thermoelectric design activity it is necessary to have an understanding of
basic module performance characteristics. Performance data is presented graphically and is
referenced to a specific heat sink base temperature. Most performance graphs are standardized at
a heat sink temperature (Th) of +50°C and the resultant data is usable over a range of
approximately 40°C to 60°C with only a slight error. We will investigate the use of a TEC1-
12706 module ,127-couple, 6-ampere to provide the required cooling.

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GRAPH: Qc vs. dT This graph, shown in Figure (10), relates a module's heat pumping capacity
(Qc) and temperature difference (TD) as a function of input current (I). In this example,
established operating parameters for the TE module
Graph 1: Heat Pumping Capacity Related to Temperature Differential as a Function of Input Current
GRAPH: Qc vs. V This graph, shown in Figure (11), relates a module's heat pumping capacity
and voltage as a function of temperature difference.
Graph 2: heat pumping capacity Related to voltage as a function of temperature difference

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GRAPH: V vs. dT This graph, relates a module's voltage and temperature differential (TD) as a
function of input current (I).
Graph 3: Voltage Related to Temperature Differential as a function of Input Current for a 127-
Couple, 6-Ampere Module
GRAPH: COP vs V
Graph 4: Coefficient of Performance Related to Voltage as a function of Input Current for a
127-Couple, 6-Ampere Module

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USE OF MULTIPLE MODULES: Relatively large thermoelectric cooling applications may
require the use of several individual modules in order to obtain the required rate of heat removal.
For such applications, TE modules normally are mounted thermally in parallel and connected
electrically in series. An electrical series-parallel connection arrangement may also be used
advantageously in certain instances. Because heat sink performance becomes increasingly
important as power levels rise, be sure that the selected heat sink is adequate for the application.
PARAMETERS OF THERMOELECTRIC MODULE
Once it is decided that thermoelectric cooler is to be considered for cooling system, the next step
is to select the thermoelectric module or cooler that can satisfy a particular set of requirements.
Modules are available in great variety of sizes, shapes, operating currents, operating voltages and
ranges of heat pumping capacity. The minimum specifications for finding an appropriate TEC by
the designer must be based on the following parameters. The cross sectional view of a TEC is
shown in Figure 19.
Figure 15: A Cross sectional View of Thermoelectric Module

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 Cold side temperature (T
c
)
 Hot side temperature (T
h
)
 Operating temperature difference ( ), which is the temperature difference between T
h
and T
c
.
 Amount of heat to be absorbed at the TEC’s cold surface. This can also be termed as
heat load. It is represented as (Q
c
) and the unit is Watts
 Operating current (I) and operating voltage (V) of the TEC.
1. Cold side temperature
If the object to be cooled is in direct contact with the cold surface of the TEC, the required
temperature can be considered the temperature of the cold side of TEC ( T
c
).Here in this project
the object is air, which has to be cooled when passed through a cluster of four Aluminium heat
sinks. The aim is to cool the air flowing through the heat sinks. When this type of system is
employed the cold side temperature of the TEC is needed to be several time colder than the
ultimate desired temperature of the air.
2. Hot side temperature
The hot side temperature ( T
h
) is mainly based on the two factors. First parameter is the
temperature of the ambient air in environment to which the heat is been rejected. Second factor
is the efficiency of the heat sink that is between the hot side of TEC and the ambient.
3. Temperature difference
The two temperatures T
c
,T
h
and the difference between them ΔT is a very important
factor. ΔT has to be accurately determined if the cooling system is expected to be operating as
desired. The following equation shows the actual ΔT.

31. Page | 31
𝚫𝑻 = 𝑻 𝒉 − 𝑻 𝒄
Actual ΔT is not same as the system ΔT. Actual ΔT is the difference between the hot and cold
side of the TEC. On the other hand system ΔT is the temperature difference between the ambient
temperature and temperature of the load to be cooled.
4. Cooling Load
The most difficult and important factor to be accurately calculated for a TEC is the
amount of heat to be removed or absorbed ( Q
c
) by the cold side of the TEC. In this project Q
c
was calculated by finding the product of finding the product of mass flow rate of air, specific
heat of air and temperature difference. Here the temperature difference system ΔT in the
difference between the inlet temperature and outlet temperature of the cooling system. The
mathematical equation for Q
c
is as shown below.
𝑸 𝒄 = 𝒎̇ 𝑪 𝒑∆𝑻
5. Thermoelectric Assembly - Heat Sinks
Thermoelectric Assemblies (TEAs) are cooling or heating systems attached to the hot side of the
TEC to transfer heat by air, liquid or conduction. TEAs which dissipate heat from the hot side
use heat exchangers. TEC requires heat exchangers or heat sinks and will be damaged if operated
without one. The two ΔTs, actual ΔT and system ΔT depend on the heat sinks fitted at the hot
sides or cold sides of TEC. The thermal resistances of the heat sinks could vary the ΔT across the
TEC for a set ambient temperature and cooling load temperature. Therefore the thermal
resistance of the heat sinks could increase the current flowing through the TEC. The three basic
types of heat sinks are: forced convective, natural convective and liquid cooled, where liquid
cooled is the most effective. The typical allowances for ΔT at the hot side heat sink of a TEC
are:
1. 10 to 15 C for a forced air cooling system with fins.- Forced convection
2. 20 to 40 C for cooling using free convection - Natural convection.

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3. 2 to 5 C for cooling using liquid heat exchangers - Liquid cooled.
There are several different types of heat exchangers available in the market. As far this
project is concerned a forced convection type of heat sink was be used based on the ΔT.
Figure 20, shows a forced convection hot side heat sink attached with a fan. The air blows
towards the heat sink from the fan will cool down the temperature of heat sink.
Figure 13: Forced convection heat sink system
The main heat sink parameter for the selection process is its thermal resistance. Heat sink
resistance can be termed as the measure of the capability of the sinkto dissipates the applied heat.
The equation is as follows:
𝑹 =
𝑻 𝒉 – 𝑻∞
𝑸 𝒉
R is the thermal resistance (in 0
C /W or K/W)
T
h
, T

is the hot side temperature and ambient temperature respectively
Qh is the heat load into the heat sink which is the sum of TEC power P
e
and heat absorbed.
𝑸 𝒉 = 𝑸 𝒄 + 𝑷 𝒆The goal of a heat sink design is to lessen the thermal resistance. It can be
attained through exposed surface area of the heat sink. It may also require forced air or liquid
cooling
Typical values of heat sink thermal resistance for natural convection range is from 0.5°C/W to
5°C/W, whereas for forced convection is from 0.02°C/W to 0.5°C/W, and water cooled is from
0.005°C/W to 0.15°C/W. Most of the thermoelectric cooling requires forced convection or water

33. Page | 33
cooled heat sinks. In this project force convective heat sink is used for the design of the cooling
system.
6. CoefficientofPerformance
The Coefficient of performance (COP) of a thermoelectric module which is the thermal
efficiency must be considered for a TE system. The selection of TEC will also be based on the
COP factor. COP is the ratio of the thermal output power and the electrical input power of the
TEC.COP can be calculated by dividing the amount of heat absorbed at the cold side to the input
power.
𝑪𝑶𝑷 =
𝑯𝒆𝒂𝒕 𝑷𝒖𝒎𝒑𝒆𝒅
𝑰𝒏𝒑𝒖𝒕 𝑷𝒐𝒘𝒆𝒓
=
𝑸𝒄
𝑷𝒊𝒏
The COP of current commercial thermoelectric refrigerators
ranges from 0.3 to 0.6, only about one-sixth the value of traditional vapor-compression
refrigerators.

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CHAPTER 6
COMPONENTS USED IN THE PROJECT MODEL
LIST OF COMPONENTS
The cooling system mainly consists of the following:
1. Thermoelectric module
2. Cooling fan (conventional fan) which cools the TE element.
3. Controller circuit which controls the fluctuations.
4. One long heat sink is fitted to the hot side of TEC to absorb heat.
5. Aluminium heat sinks that are attached to the cold side.
6. An AC source which is given to transformer.
7. A Transformer (Step down).
8. A Rectifier to converts the AC into DC supply.
9. Dc power supply is used to drive the TEC.
10. Containing Box.
11. Solar Panels.
12. Discharge Fan.
13. Switches.

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DESCRIPTION OF THE COMPONENTS
THERMOELECTRIC MODULE
A thermoelectric device will create a voltage when there is temperature difference on each side
of the device. On the other hand when a voltage is applied to it, a temperature difference is
created. The temperature difference is also known as Peltier effect. Thus TEC operates by the
Peltier effect, which stimulates a difference in temperature when an electric current flows
through a junction of two dissimilar materials.
In this project we used TEC1-12706 module with 127 couples, 40 mm × 40 mm size single stage
module is made of selected high performance ingot to achieve superior cooling performance and
greater delta T up to 70 °C, designed for superior cooling and heating up to 100 ºC requirement
Figure Peltier Module
TRANSFORMER
In this project, Step down transformer is used for the purpose of reduce the voltage. We know
that the voltage supplied to our home is 220V, but we need only 12V for our project. So there is
a need to reduce the voltage by the help of step down Transformer.

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In transformer, there are two coils one is Primary coil & one is secondary coil. The input 220v is
connected to the primary coil. And output voltage is put on the secondary coil.
Figure 16: Transformer
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. Bridge Rectifier is used in our
design.
Figure 17: Rectifier

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COOLLING FAN
Fan is a machine used to create flow with in a fluid, typically gas such as air. Fan consists of a
rotating arrangement of vanes or blades which act on the fluid. Blades are attached on the
periphery of a hub called as impeller & the rotating assembly is known as runner or rotor. All the
moving parts are enclosed in a case. This directs the air flow as well as act as a safeguard for the
other components from the moving blades. Most fans are powered by electric motors, but other
sources of power may be used (such as hydraulic power).Fan is generally used for cooling
purposes besides it has also other application. Cooling fans become essential component in
nearly all electronic equipments .Fan’s purpose to ensure cool operating temperature. It draws
the cooler air from outside atmosphere & expels warm air from inside to maintain suitable
operating temperature. It applies right amount of cool air to the components, protecting against
heat that can harm electronics & effects the performance. Its angled blades guide air outside of
the device into the device where the heat emission occurs, in a single direction. It also dejects the
warm air from the inside of the device.
In this device a fan is incorporated under the lower side of the heat radiator. When heat generates
at the hot junction of peltier module, it extracts heat from the source & provide cool air to
maintain operating temperature. 12V DC-0.14A fan is used in this device.
It is made by Yate Loon Company Ltd. Dimensions of this fan are 92mm*92mm*25mm
(W*L*H).
Figure 18: Cooling Fan

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Heat Sink
A heat sink is a passive heat exchanger that cools a device by dissipating heat into surrounding
medium. Heat is transferred to the air by conduction and convection; a relatively small
proportion of heat is transferred by radiation owing to the low temperature of semiconductor
devices compared to their surroundings
.
A heat sink transfers thermal energy from a higher temperature device to a lower temperature
fluid medium. The fluid medium is frequently air, but can also be water, refrigerants or oil. If the
fluid medium is water, the heat sink is frequently called a cold plate. In thermodynamics a heat
sink is a heat reservoir that can absorb an arbitrary amount of heat without significantly changing
temperature. Practical heat sinks for electronic devices must have a temperature higher than the
surroundings to transfer heat by convection, radiation, and conduction.
Figure 1 Heat Sink

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From the Fourier’s Law of Heat Conduction & Newton’s Law of Cooling,we can determine how
much heat transfer happens by conduction theoretically.
 To design a heat sink there are some factors must be followed which are given below:
 Thermal resistance
 Material
 Fin efficiency
 Spreading resistance
 Shape of the fins
 Location of the fins
 Fin arrangements
 Conductivity of the material
 Surface color
The popular heat sink materials are aluminium alloys. Aluminium alloys 6061 & 6063 are
commonly used. Copper also has excellent heat sink properties.. There are also various types of
fin arrangements in heat sinks such as pin fin, straight fin, flared fin etc. In general, the more
surface area a heat sink has, the better it works.We used straight fin heat sink as a heat dissipator.
In our device heat sink is placed between peltier module & 12V DC fan. It is straight fin type,
portable & it is adhered by thermal paste.
Solar Cell Panel
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 more light that hits a cell, the more
electricity it produces.

40. Page | 40
A photovoltaic system typically includes a panel or an array of solar modules, an 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. Electrical connections are made in series to achieve a
desired output voltage and/or in parallel to provide a desired current capability.
Figure: Solar Cell Panel

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Ice Box
An icebox or cold closet is a compact non-mechanical refrigerator which was common kitchen
appliance before the development of safe powered refrigeration devices. The Ice Box is a Food
Tab structure used to store and preserve Food, reducing spoilage rate by 50% (so edible items
stored in an Ice Box will last twice as long before spoiling).
This ice box is made of thermo setting plastic & thermocol. Its wall is insulating. The following
items can be placed in the ice box: many food items, petals & ice.It is portable & in the lower
part the cold junction of the peltier module is exposed. Inner surface of box is covered by
aluminium sheets because it helps in uniform transfer of heat. It is easy to carry, easy to dispatch
& easy to assemble.
Figure 2 Ice Box

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Battery
An electric battery is a device consisting of one or more electrochemical cells that convert stored
chemical energy into electrical energy. Each cell contains a positive terminal or cathode and a
negative terminal, or anode. Electrolytes allow ions to move between the electrodes and
terminals, which allows current to flow out of the battery to perform work.
Primary (single-use or disposable) batteries are used once and discarded; the electrode materials
are irreversibly changed during discharge. Common examples are the alkaline battery used for
flashlights and a multitude of portable devices. Secondary (rechargeable batteries) can be
discharged and recharged multiple times; the original composition of the electrodes can be
restored by reverse current. Examples include the batteries used in vehicles and lithium ion
batteries used for portable electronics.
Batteries come in many shapes and sizes, from miniature cells used to power aids and
wristwatches to battery banks the size of rooms that provide standby power for telephone and
computer data centers.
In this device three 4V rechargeable batteries are used. This Battery is charged by solar cell
panel.

43. Page | 43
EXPENDITURE ON PROJECT
1. Solar panel 12v 1300
2. Battery 12v 950
3. TE module refrigerator 1000
4. Heat sink (4”x4”) 400
5. Exhaust fan (4”) 350
6. diode, Resistance, capacitor, transformer 500
7. ROOM temp thermometer 350
8. Others 300
Total 5150

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CHAPTER 7
THERMOELECTRIC MATERIALS
Thermoelectric materials show the thermoelectric effect in a strong and convenient form. The
thermoelectric effect refers to phenomena in which a temperature difference creates an electric
potential or electric potential creates a temperature difference. Specifically, the Seeback effect
(temperature-current), Peltier effect (current-temperature), and Thomson effect (conductor
heating/cooling). While all materials have a nonzero thermoelectric effect, in most materials it is
too small to be useful. However, low cost materials that have a sufficiently strong thermoelectric
effect (and other required properties) could be used for applications including power generation,
refrigeration and a variety of other applications.
A commonly used thermoelectric material in such applications is Bismuth telluride (Bi2Te3).
Materials of interest
Strategies to improve thermoelectric include both advanced bulk materials and the use of low-
dimensional systems. Such approaches to reduce lattice thermal fall under two general material
types:
1) Alloys: create point defects, vacancies, or rattling structures (heavy-ion species with
large vibration amplitudes contained within partially filled structural sites) to scatter
phonons within the unit cell crystal.
2) Complex crystals: separate the phonon-glass from the electron crystal using approaches
similar to those for superconductors.
Materials under consideration for thermoelectric device applications include:

45. Page | 45
Bismuth chalcogenides
Materials such as Bi2Te3 and Bi2Se3 comprise some of the best performing room temperature
thermoelectric with a temperature-independent thermoelectric effect (ZT) between 0.8 and 1.0.
Nano structuring these materials to produce a layered super lattice structure of alternating Bi2Te3
and Bi2Se3 layers produces a device within which there is good electrical conductivity but
perpendicular to which thermal conductivity is poor. The result is an enhanced ZT
(approximately 2.4 at room temperature for p-type). Note that this high value has not entirely
been independently confirmed.
Skutterudite thermoelectric
Recently, Skutterudite materials have sparked the interest of researchers in search of new
thermoelectric these structures are of the form (Co, Ni, Fe) (P, Sb, As) and are cubic with space
group Im3. Unfilled, these materials contain voids into which low-coordination ions (usually rare
earth elements) can be inserted in order to alter thermal conductivity by producing sources for
lattice phonon scattering and decrease thermal conductivity due to the lattice without reducing
electrical conductivity. Such qualities make these materials exhibit PGEC behavior.
Oxide thermoelectric
Due to the natural super lattice formed by the layered structure in homologous compounds
(such as those of the form (SrTiO3)n (SrO)m the Ruddleson-Popper phase), oxides have potential
for high-temperature thermoelectric devices. These materials exhibit low thermal conductivity
perpendicular to these layers while maintaining electrical conductivity within the layers. The
figure of merit in oxides is still relatively low (~0.34 at 1,000K), but the enhanced thermal
stability, as compared to conventional high-ZT bismuth compounds, makes the oxides superior
in high-temperature applications.
Nanomaterials
In addition to the nanostructures Bi2/Bi2Se3 super lattice thin films that have shown a great deal
of promise, other nanomaterials show potential in improving thermoelectric materials. One

46. Page | 46
example involving PbTe/PbSeTe quantum dot super lattices provides an enhanced ZT
(approximately 1.5 at room temperature) that was higher than the bulk ZT value for either PbTe
or PbSeTe (approximately 0.5). Individual silicon nano wires can act as efficient thermoelectric
materials, with ZT values approaching 1.0 for their structures, even though bulk silicon is a poor
thermoelectric material (approximately 0.01 at room temperature) because of its high thermal
conductivity.

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CHAPTER 8
APPLICATION FOR THERMOELECTRIC COOLERS
Applications for thermoelectric modules cover a wide spectrum of product areas. These include
equipment used by military, medical, industrial, consumer, scientific laboratory, and
telecommunications organizations. Uses range from simple food and beverage coolers for an
afternoon picnic to extremely sophisticated temperature control systems in missiles and space
vehicles.
Unlike a simple heat sink, a thermoelectric cooler permits lowering the temperature of an
object below ambient as well as stabilizing the temperature of objects which are subject to
widely varying ambient conditions. A thermoelectric cooler is an active cooling module whereas
a heat sink provides only passive cooling.
Thermoelectric coolers generally may be considered for applications that require heat
removal ranging from milliwatts up to several thousand watts. Most single-stage TE coolers,
including both high and low current modules, are capable of pumping a maximum of 3 to 6 watts
per square centimeter (20 to 40 watts per square inch) of module surface area. Multiple modules
mounted thermally in parallel may be used to increase total heat pump performance. Large
thermoelectric systems in the kilowatt range have been built in the past for specialized
applications such as cooling within submarines and railroad cars. Systems of this magnitude are
now proving quite valuable in applications such as semiconductor manufacturing lines.
Typical applications for thermoelectric modules include:
 Box Cooling
 Calorimeters
 Cold Chambers
 Cold Plates
 Compact Heat Exchangers
 Constant Temperature Baths
 Dehumidifiers

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 Dew Point Hygrometers
 Environmental Analysers
 Heat Density Measurement
 Ice Point References
 Immersion Coolers
 Integrated Circuit Cooling
 Low Noise Amplifiers
 Microtome Stage Coolers
 Night Vision Equipment
 Osmometers
 Parametric Amplifiers
 Refrigerators and on-board refrigeration systems (Aircraft, Automobile, Boat, Hotel,
Insulin, Portable/Picnic, Pharmaceutical, RV)
 Stir Coolers
 Thermal Viewers and Weapons Sights
 Water and Beverage Coolers
 Wet Process Temperature Controller
 Wine Cabinets
Uses- Peltier devices are commonly used in camping and portable coolers and for cooling
electronic components and small instruments. Some electronic equipment intended for military
use in the field is thermoelectrically cooled. The cooling effect of Peltier heat pumps can also be
used to extract water from the air in dehumidifiers.
Peltier elements are a common component in thermal cyclers, used for the synthesis of DNA by
polymerase chain reaction (PCR)a common molecular biological technique which requires the
rapid heating and cooling of the reaction mixture for denaturation, primer annealing and
enzymatic synthesis cycles.
The effect is used in satellites and spacecraft to counter the effect of direct sunlight on one side
of a craft by dissipating the heat over the cold shaded side, whereupon the heat is dissipated by
thermal radiation into space.

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German automakers Volkswagen and BMW have developed thermoelectric generators (TEG)
that recover waste heat from a combustion engine. BMW and DLR (German Aerospace) have
also developed an exhaust powered thermoelectric generator that achieves 200 W maximum and
has been used successfully for more than 12,000-km road use.
Space probes to the outer solar system make use of the effect in radioisotope thermoelectric
generators for electrical power.
ADVANTAGES OF THERMOELECTRIC REFRIGERATION SYSTEM
COMPACT SIZE: The space required by the cooling system is very little.
LIGHTWEIGHT: The unit is very portable which can be carried with one hand and is
unaffected by motion or tilting.
LOW PRICE: 20% - 40% less expensive than compressor or absorption units.
LOW BATTERY: The battery used is of low voltage, 12V.
HEATING OPTION: This unit can also be used for heating operations.
SAFETY: No toxic refrigerant or open flames, propane.
RELIABILITY: Thermo-electrics provide a substantial degree of reliability of long period.
EASY SERVICE: The parts can be easily replaced by a screwdriver.
LOW MAINTENANCE: This unit requires no maintenance at all due to absence of moving
parts.

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CHAPTER 8
CONCLUSION
The project aims to design and build a miniature prototype of thermoelectric refrigeration system
for a conventional refrigerator to provide refrigeration. The system was targeted as a refrigerator
and temperature of the cooled air should be lowered 20 degree Celsius from ambient
temperature. Secondary objective of the project includes design of a dc power supply and a
temperature controller circuit. The idea of refrigeration is based on Peltier effect, as when a dc
current flows through TE modules it generates a heat transfer and temperature difference across
the ceramic substrates causing one side of the module to be cold and the other side to be hot. The
analysis shows that for the prevalent conditions in Eliath, the compressor less refrigerator is
significantly more economical to own and operate then the conventional refrigerator. In spite of a
slightly higher initial cost, the thermoelectric refrigerator proves to be more economical, mainly
due to its significantly lower operating cost.
After the completion of the project it can be concluded that compressor less refrigeration is
possible and can be done using thermoelectric effect (Peltier effect). Using the peltier effect not
only refrigerators but heat pumps also can be made which will simultaneously heat and cool
substances. These compressor-less refrigerators are very cheap to manufacture, have less number
of moving parts, portable and can be used efficiently in hot weather.
This project can be easily upgraded using more number of peltier unit, fan and by building its
body using terracotta clay or any other suitable substance which will further increase the cooling
inside the refrigerator. This will make the refrigeration effective and also increase its COP. Since
it is portable, lower priced, require low maintenance and the power source used in this project is
solar power, which is a renewable energy source we believe that its demand is going to increase
in future.