User:Anuj kumar mandal/sandbox

my project THERMO ELECTRIC GENERATOR Dr.M.G.R Educational and Research Institute University H&S Campus, Adayalampattu, Chennai – 600 095

Dr.M.G.R. Educational & Research Institute University Chennai – 95

PROJECT WORK

THERMOELECTRIC GENERATOR

REGISTER NO:

Name of the Lab : Project Lab

Certified that this is a bonafide record of project work done by -- of -Section and --- Branch, during the year 2012-2013. Project Advisor			Project Coordinator Project Examiner

ABSTRACT Thermoelectric modules are an important alternative to heat engines in the harvesting of waste heat. Electrical-thermal analogues are often employed when studying heat conduction and this analogue can be extended to develop an equivalent circuit for thermoelectric effects. For the primarily one-dimensional problem of thermoelectricity, the equations can be discretized to create a simple mathematical model. In this document, such a model is developed from first principles and show that the electro-thermal coupling is properly incorporated. The results of simulations using the model are then presented and validated experimentally. Furthermore, in one possible application of thermoelectric modules, a self-contained cooling unit with an integrated thermoelectric generator is designed. By performing fluid dynamics simulations on a fan and heat sink model, the geometry and operating conditions can be optimized and the start-up and transient characteristics are studied.

1

CONTENTS TOPIC                                                                     PAGE

1.	Introduction

2.	Specification

3.	Description

4.	Working

5.	Diagrams

6.	Input and Output

7.	Advantages and Disadvantages

8.	Application

9.	Conclusion

10.	Reference

2

1.	INTRODUCTION THERMOELECTRIC GENERATOR Thermoelectric generators (also called Seebeck generators) are devices that convert heat (temperature differences) directly into electrical energy, using a phenomenon called the "Seebeck effect" (or "thermoelectric effect"). Their typical efficiencies are around 5–8%. Older Seebeck-based devices used bimetallic junctions and were bulky. More recent devices use semiconductor p–n junctions made from bismuth telluride (Bi2Te3), lead telluride (PbTe), calcium manganese oxide, or combinations thereof, depending on temperature. These are solid-state devices and unlike dynamos have no moving parts, with the occasional exception of a fan or pump. Radioisotope thermoelectric generators can provide electric power for spacecraft. Automotive thermoelectric generators are proposed to recover usable energy from automobile waste heat.

3

2.SPECIFICATIONS 	TEG MODULE 	HEATSINK 	MULTIMETER 	D.C. MOTOR 	PLY WOOD 	WATER 	HAIR DRYER 	CONNECTING WIRES

4

3.DESCRIPTION

	TEG MODULE Thermoelectric generators are devices that convert heat (temperature differences) directly into electrical energy, using a phenomenon called the "Seebeck effect" (or "thermoelectric effect"). Their typical efficiencies are around 5–8%. Older Seebeck-based devices used bimetallic junctions and were bulky. More recent devices use semiconductor p–n junctions made from bismuth telluride (Bi2Te3), lead telluride (PbTe), calcium manganese oxide, or combinations thereof, depending on temperature. These are solid-state devices and unlike dynamos have no moving parts, with the occasional exception of a fan or pump. Radioisotope thermoelectric generators can provide electric power for spacecraft. Automotive thermoelectric generators are proposed to recover usable energy from automobile waste heat

HEATSINK

This article is about components used to cool semiconductors. For other uses, see Heat sink (disambiguation).A fan-cooled heat sink on the processor of a personal computer. To the right is a smaller heat sink cooling another integrated circuit of the motherboard. In electronic systems, a heat sink is a passive heat exchanger component that cools a device by dissipating heat into the surrounding air. 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 optoelectronic devices such as lasers and light emitting diodes (LEDs), wherever the heat dissipation ability of the basic device package is insufficient to control its temperature. A heat sink is designed to increase the surface area in contact with the cooling medium surrounding it, such as the air. Approach air velocity, choice of material, fin (or other protrusion) design and surface treatment are some of the factors which affect the thermal performance of a heat sink. Heat sink attachment methods and thermal interface materials alsoaffect the eventual die temperature of the integrated circuit. Thermal adhesive or thermal grease fills the air gap between the heat sink and device to improve its thermal performance. Theoretical, experimental and numerical methods can be used to determine a heat sink's thermal performance. 	MULTIMETER

A multimeter, also known as a VOM (Volt-Ohm meter), is an electronicmeasuring instrument that combines several measurement functions in one unit. A typical multimeter would include basic features such as the ability to measure voltage, current, and resistance. Digital multimeter (DMM, DVOM) display the measured value in numerals, and may also display a bar of a length proportional to the quantity being measured. Digital multimeters have all but replaced analog moving coil multimeters in most situations. A multimeter can be a hand-held device useful for basic fault finding and field service work, or a bench instrument which can measure to a very high degree of accuracy. They can be used to troubleshoot electrical problems in a wide array of industrial and household devices such as electronic equipment, motor controls, domestic appliances, power supplies, and wiring systems.

	D.C. MOTOR

A DC motor is a mechanically commutated electric motor powered from direct current (DC). The stator is stationary in space by definition and therefore it’s current. The current in the rotor is switched by the commutator to also be stationary in space. This is how the relative angle between the stator and rotor magnetic flux is maintained near 90 degrees, which generates the maximum torque. DC motors have a rotating armature winding (winding in which a voltage is induced) but non-rotating armature magnetic field and a static field winding (winding that produce the main magnetic flux) or permanent magnet. Different connections of the field and armature winding provide different inherent speed/torque regulation characteristics. The speed of a DC motor can be controlled by changing the voltage applied to the armature or by changing the field current. The introduction of variable resistance in the armature circuit or field circuit allowed speed control. Modern DC motors are often controlled by power electronics systems called DC drives. The introduction of DC motors to run machinery eliminated the need for local steam or internal combustion engines, and line shaft drive systems. DC motors can operate directly from rechargeable batteries, providing the motive power for the first electric vehicles. Today DC motors are still found in applications as small as toys and disk drives, or in large sizes to operate steel rolling mills and paper machines. 	PLY WOOD

Plywood is a manufactured wood panel made from thin sheets of wood veneer. It is one of the most widely used wood products. It is flexible, inexpensive, workable, and re-usable, and usually can be manufactured locally. Plywood is used instead of plain wood because of plywood's resistance to cracking, shrinkage, splitting, and twisting/warping, and because of its generally high strength.

	WATER

The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice-versa. A thermoelectric device creates voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, it creates a temperature difference. At the atomic scale, an applied temperature gradient causes charge carriers in the material to diffuse from the hot side to the cold side. This effect can be used to generate electricity, measure temperature or change the temperature of objects. Because the direction of

heating and cooling is determined by the polarity of the applied voltage, thermoelectric devices can be used as temperature controllers.

	HAIR DRYER

Hair dryer is used to heat the top side of thermoelectric generator as to increase the top temperature of TEG module. The hair dryer is giving hot air. The bottom side is cool as compared to top as due to presence of cold water. The temperature difference between the top and the bottom layer produces electricity in TEG module.

	CONNECTING WIRES

Connecting  Wires, commonly used with a breadboard, are used to transfer electrical signals from one part of the breadboard to the central microcontroller. Jump wires vary in size and colour to distinguish what object they are working with. Sensors, buttons, and other such things all use connecting wires to communicate with the microcontroller.

4 WORKING Thermoelectric generators are devices that convert heat (temperature differences) directly into electrical energy, using a phenomenon called the "Seebeck effect" (or "thermoelectric effect"). Their typical efficiencies are around 5–8%. Older Seebeck-based devices used bimetallic junctions and were bulky. More recent devices use semiconductor p–n junctions made from bismuth telluride (Bi2Te3), lead telluride (PbTe), calcium manganese oxide, or combinations thereof, depending on temperature. These are solid-state devices and unlike dynamos have no moving parts, with the occasional exception of a fan or pump. Radioisotope thermoelectric generators can provide electric power for spacecraft. Automotive thermoelectric generators are proposed to recover usable energy from automobile waste heat. HEATSINK This article is about components used to cool semiconductors. For other uses, see Heat sink (disambiguation).A fan-cooled heat sink on the processor of a personal computer. To the right is a smaller heat sink cooling another integrated circuit of the motherboard. In electronic systems, a heat sink is a passive heat exchanger component that cools a device by dissipating heat into the surrounding air. 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 optoelectronic devices such as lasers and light emitting diodes (LEDs), wherever the heat dissipation ability of the basic device package is insufficient to control its temperature. A heat sink is designed to increase the surface area in contact with the cooling medium surrounding it, such as the air. Approach air velocity, choice of material, fin (or other protrusion) design and surface treatment are some of the factors which affect the thermal performance of a heat sink. Heat sink attachment methods and thermal interface materials also affect the eventual die temperature of the integrated circuit. Thermal adhesive or thermal grease fills the air gap between the heat sink and device to improve its thermal performance. Theoretical, experimental and numerical methods can be used to determine a heat sink's thermal performance. A multimeter, also known as a VOM (Volt-Ohm meter), is an electronicmeasuring instrument that combines several measurement functions in one unit. A typical multimeter would include basic features such as the ability to measure voltage, current, and resistance. Digital multimeter (DMM, DVOM) display the measured value in numerals, and may also display a bar of a length proportional to the quantity being measured. Digital multimeters have all but replaced analog moving coil multimeters in most situations. A multimeter can be a hand-held device useful for basic fault finding and field service work, or a bench instrument which can measure to a very high degree of accuracy. They can be used to troubleshoot electrical problems in a wide array of industrial and household devices such as electronic equipment, motor controls, domestic appliances, power supplies, and wiring systems. A DC motor is a mechanically commutated electric motor powered from direct current (DC). The stator is stationary in space by definition and therefore it’s current. The current in the rotor is switched by the commutator to also be stationary in space. This is how the relative angle between the stator and rotor magnetic flux is maintained near 90 degrees, which generates the maximum torque. DC motors have a rotating armature winding (winding in which a voltage is induced) but non-rotating armature magnetic field and a static field winding (winding that produce the main magnetic flux) or permanent magnet. Different connections of the field and armature winding provide different inherent speed/torque regulation characteristics. The speed of a DC motor can be controlled by changing the voltage applied to the armature or by changing the field current. The introduction of variable resistance in the armature circuit or field circuit allowed speed control. Modern DC motors are often controlled by power electronics systems called DC drives. The introduction of DC motors to run machinery eliminated the need for local steam or internal combustion engines, and line shaft drive systems. DC motors can operate directly from rechargeable batteries, providing the motive power for the first electric vehicles. Today DC motors are still found in applications as small as toys and disk drives, or in large sizes to operate steel rolling mills and paper machines. PLY WOODPlywood is a manufactured wood panel made from thin sheets of wood veneer. It is one of the most widely used wood products. It is flexible, inexpensive, workable, and re-usable, and usually can be manufactured locally. Plywood is used instead of plain wood because of plywood's resistance to cracking, shrinkage, splitting, and twisting/warping, and because of its generally high strength. WATER The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice-versa. A thermoelectric device creates voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, it creates a temperature difference. At the atomic scale, an applied temperature gradient causes charge carriers in the material to diffuse from the hot side to the cold side. This effect can be used to generate electricity, measure temperature or change the temperature of objects. Because the direction of heating and cooling is determined by the polarity of the applied voltage, thermoelectric devices can be used as temperature controllers. Hair dryer is used to heat the top side of thermoelectric generator as to increase the top temperature of TEG module. The hair dryer is giving hot air. The bottom side is cool as compared to top as due to presence of cold water. The temperature difference between the top and the bottom layer produces electricity in TEG module. Connecting  Wires, commonly used with a breadboard, are used to transfer electrical signals from one part of the breadboard to the central microcontroller. Jump wires vary in size and colour to distinguish what object they are working with. Sensors, buttons, and other such things all use connecting wires to communicate with the microcontroller. WORKING IN BRIEF 	First the box is filled with water to produce lower temperature on the bottom side of TEG module. 	Second the hair dryer is taken and is made to heat the top surface of TEG module for increasing the temperature on the top side of TEG. 	The temperature difference causes electricity to be produced in the TEG module. 	This is measured using multimeter where the reading of the current is noted. 	The presence of current can be shown practically by connecting the TEG module to a D.C. motor where the fan rotates.

THERMOELECTRIC EFFECT The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice-versa. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, it creates a temperature difference. At the atomic scale, an applied temperature` gradient causes charged carriers in the material to diffuse from the hot side to the cold side , similar to a classical gas that expands when heated ; hence inducing a thermal current.This effect can be used to generate electricity, measure temperature or change the temperature of objects. Because the direction of heating and cooling is determined by the polarity of the applied voltage, thermoelectric devices are efficient temperature controllers. The term “thermoelectric effect” encompasses three separately identified effects: the Seebeck effect, Peltier effect and Thomson effect. Textbooks may refer to it as the Peltier-Seebeck effect. This separation derives from the independent discoveries of French physicist Jean Charles Athanase Peltier and Estonian–German physicist Thomas Johann Seebeck. Joule heating, the heat that is generated whenever a voltage is applied across a resistive material is related though it is not generally termed a thermoelectric effect. The Peltier-Seebeck and Thomson effects are thermodynamically reversible, whereas joule heating is not. SEEBECK EFFECT A thermoelectric circuit composed of materials of different Seebeck coefficient (p-doped and n-doped semiconductors), configured as a thermoelectric generator. If the load is removed then the current stops, and the circuit functions as a temperature-sensing thermocouple. The Seebeck effect is the conversion of temperature differences directly into electricity and is named after the Baltic German physicist Thomas Johann Seebeck, who, in 1821 discovered that a compass needle would be deflected by a closed loop formed by two metals joined in two places, with a temperature difference between the junctions. This was because the metals responded differently to the temperature difference, creating a current loop and a magnetic field. Seebeck did not recognize there was an electric current involved, so he called the phenomenon the thermomagnetic effect. Danish physicist Hans Christian Ørsted rectified the mistake and coined the term "thermoelectricity".The Seebeck effect is a classic example of an electromotive force (emf) and leads to measurable currents or voltages in the same way as any other emf. Electromotive forces modify Ohm's law by generating currents even in theabsence of voltage differences (or vice versa); the local current density is given by Where is the local voltage and is the local conductivity. In general the Seebeck effect is described locally by the creation of an electromotive field Where is the Seebeck coefficient (also known as thermo power), a property of the local material, and is the gradient in temperature. The Seebeck coefficients generally vary as function of temperature, and depend strongly on the composition of the conductor. For ordinary materials at room temperature, the Seebeck coefficient may range in value from −100 μV/K to +1000 μV/K (see thermoelectric materials). If the system reaches a steady state where, then the voltage gradient is given simply by the emf:. This simple relationship, which does not depend on conductivity, is used in the thermocouple to measure a temperature difference; an absolute temperature may be found by performing the voltage measurement at a known reference temperature. Conversely, a metal of unknown composition can be classified by its thermoelectric effect if a metallic probe of known composition, kept at a constant temperature, is held in contact with it (the unknown material is locally heated to the probe temperature). Industrial-quality control instruments use this as thermoelectric alloy sorting to identify metal alloys. Thermocouples in series form a thermopile, sometimes constructed in order to increase the output voltage, because the voltage induced over each individual couple is small. Thermoelectric generators are used for creating power from heat differentials and exploit this effect. THERMO POWER The thermo power, or thermoelectric power (also called the See beck coefficient) of a material is a measure of the magnitude of an induced thermoelectric voltage in response to a temperature difference across that material The thermo power has units of volts per kelvin (V/K), although it is more often given in microvolts per kelvin (μV/K). Thermopower is a misnomer. What is called thermopower would be more correctly dubbed thermoelectric sensitivity as it measures the voltage or electric potential (not the electric power) induced in response to a temperature difference. Note that the unit of thermo power (V/K) is different from the unit of power (watts). The phenomenon quantified by thermo power is called the Seebeck effect. The Seebeck effect and two related phenomena (the Peltier effect and Thomson effect) are together called the "thermoelectric effect". An applied temperature difference causes charged carriers in the material, whether they are electrons or holes, to diffuse from the hot side to the cold side, similar to a gas that expands when heated. Mobile charged carriers migrating to the cold side leave behind their oppositely charged and immobile nuclei at the hot side thus giving rise to a thermoelectric voltage (thermoelectric refers to the fact that the voltage is created by a temperature difference). Since a separation of charges also creates an electric field, the build-up of charged carriers onto the cold side eventually ceases at some maximum value since there exists an equal amount of charged carriers drifting back to the hot side as a result of the electric field at equilibrium. Only an increase in the temperature difference can resume a build-up of more charge carriers on the cold side and thus lead to an increase in the thermoelectric voltage. Incidentally the thermopower also measures the entropy per charge carrier in the material. The thermopower of a material, represented as, depends on the material's temperature, and crystal structure. Typically metals have small thermopowers because most have half-filled bands. Electrons (negative charges) and holes (positive charges) both contribute to the induced thermoelectric voltage thus cancelling each other's contribution to that voltage and making it small. In contrast, semiconductors can be doped with an excess amount of electrons or holes and thus can have large positive or negative values of the thermopower depending on the charge of the excess carriers. The sign of the thermopower can determine which charged carriers dominate the electric transport in both metals and semiconductors. Superconductors have zero thermopower since the charged carriers carry no entropy. Equivalently, the thermopower is zero because it is impossible to have a finite voltage across a superconductor. (For example, by Ohm's law, V=IR=0, since the resistance, R, is equal to zero in a superconductor.) DEFINITION If the temperature difference ΔT between the two ends of a material is small, then the thermo power of a material is defined as: Where ΔV is the thermoelectric voltage seen at the terminals in steady-state when the current is zero. (See below for more on the signs of ΔV and ΔT.) This can also be written in relation to the electric field and the temperaturegradient, by the equation: Strictly speaking, these two expressions are not quite the same, and it is the first, not the second, which agrees with the practical, experimental definition. (They differ because voltage, defined here as "the quantity measured with a voltmeter", depends not only on the electric field but also the internal chemical potential gradient of electrons in the material CHARGE-CARRIER DIFFUSION Charge carriers in the materials will diffuse when one end of a conductor is at a different temperature from the other. Hot carriers diffuse from the hot end to the cold end, since there is a lower density of hot carriers at the cold end of the conductor, and vice versa. If the conductor were left to reach thermodynamic equilibrium, this process would result in heat being distributed evenly throughout the conductor (see heat transfer). The movement of heat (in the form of hot charge carriers) from one end to the other is a heat current and an electric current as charge carriers are moving. In a system where both ends are kept at a constant temperature difference, there is a constant diffusion of carriers. If the rate of diffusion of hot and cold carriers in opposite directions is equal, there is no net change in charge. The diffusing charges are scattered by impurities, imperfections, and lattice vibrations or phonons. If the scattering is energy dependent, the hot and cold carriers will diffuse at different rates, creating a higher density of carriers at one end of the material and an electrostatic voltage. This electronic contribution to the Seebeck coefficient is described by the Mott relation, where is the conductivity of electrons at an energy,  is the whole conductivity given by  , and the function  is the energy occupation function. The Fermi level is defined by. The fact that the Seebeck coefficient depends on the structure of near  means that the thermopower of a material depends greatly on impurities, imperfections, and structural changes, all of which can vary with temperature and electric field. DEVICE EFFICIENCY The efficiency of a thermoelectric device for electricity generation is given by, defined as The ability of a given material to efficiently produce thermoelectric power is related to its dimensionless figure of merit given by: , Which depends on the Seebeck coefficientS, thermal conductivityλ,　and electrical conductivityσ, and temperature T. In an actual thermoelectric device, two materials are used. The maximum efficiency is then given by where  is the temperature at the hot junction and  is the temperature at the surface being cooled. is the modified dimensionless figure of merit, which takes into consideration the thermoelectric capacity of both thermoelectric materials being used in the device and is defined as where is the electrical resistivity,  is the average temperature between the hot and cold surfaces and the subscripts n and p denote properties related to the n- and p-type semiconducting thermoelectric materials, respectively. Since thermoelectric devices are heat engines, their efficiency is limited by the Carnot efficiency, hence the and  terms in. Regardless, the coefficient of performance of current commercial thermoelectric refrigerators ranges from 0.3 to 0.6, one-sixth the value of traditional vapour-compression refrigerators

TEG MODULE THERMOELECTRIC GENERATORS Thermoelectric generatoris an application of thermoelectric effect.The Seebeck effect is used in thermoelectric generators, which function like heat engines, but are less bulky, have no moving parts, and are typically more expensive and less efficient. They have a use in power plants for converting waste heat into additional electrical power (a form of energy recycling), and in automobiles as automotive thermoelectric generators (ATGs) for increasing fuel efficiency. Space probes often use radioisotope thermoelectric generators with the same mechanism but using radioisotopes to generate the required heat difference. Commercially available examples can be found in self-powered fans and chargers designed for use on wood stoves

PELTIER EFFECT The Peltier effect can be used to create a refrigerator which is compact and has no circulating fluid or moving parts; such refrigerators are useful in applications where their advantages outweigh the disadvantage of their very low efficiency. TEMPERATURE MEASUREMENT Thermocouples and thermopiles are devices that use the Seebeck effect to measure the temperature difference between two objects, one connected to a voltmeter and the other to the probe. The temperature of the voltmeter, and hence that of the material being measured by the probe, can be measured separately using cold junction compensation techniques.

THERMOELECTRIC POWER GENERATION The thermoelectric effect is sometimes used to generate electrical power, starting from a source of a temperature gradient. For example, some spacecraft are powered by a radioisotope thermoelectric generator, exploiting the temperature difference between a radioactively-heated plate and the cold empty space surrounding the craft. Some researchers hope that, in the future, much wider use could be made of thermoelectric power generation, including using waste heat from automobiles (see Automotive Thermoelectric Generators) and power plants. (This is a form of energy recycling.) The efficiency with which a thermoelectric material can generate electrical power depends on several material properties, of which perhaps the most important is the thermopower. A larger induced thermoelectric voltage for a given temperature gradient will lead to a higher efficiency. Ideally one would want very large thermopower values since only a small amount of heat is then necessary to create a large voltage. This voltage can then be used to provide power. There is an active research effort to find materials that could make cheaper and more efficient thermoelectric power generators; to learn more see the article thermoelectric materials.

PRODUCTION OFTHERMOELECTRIC GENERATORS MARLOW INDUSTRIES HEADQUARTERS	Dallas

Marlow Industries TYPE Public, Subsidiary

FOUNDED	1973 KEY PEOPLE	Raymond Marlow, Founder Barry Nickerson, General Manager PRODUCTS	Thermoelectric Cooling

EMPLOYEES	1000-2000 MARLOW INDUSTRIES Marlow Industries is a manufacturer of thermoelectric modules and is a subsidiary of II-VI Incorporated, based in Dallas, Texas. The company develops and manufactures thermoelectric products – such as power generators, thermoelectric coolers (TECs), subsystems, and end-products – and serves the aerospace, defence, medical, commercial, industrial, and telecommunications markets Marlow Industries began after Raymond Marlow founded the company in 1973 as a five-person team that focused on thermoelectric cooling technology for the defence sector In 1991, Marlow Industries was the second small US-based company to receive the Malcolm Baldridge National Quality Award, an award created by Congress to recognize American world-class quality companies; Marlow Industries was recognized for its work to improve the company through Total Quality Management. In 2004, the company was acquired by II-VI Incorporated. Marlow Industries became a subsidiary of the company and began operating within II-VI’s Compound Semiconductor Group. A year later, in 2005, the company opened its manufacturing plant in Ho Chi Minh City, Vietnam. When the factory opened, it focused on thermoelectric module assembly lines for standard commercial products. It now includes various market assembly lines and an engineering design center. In 2007, Marlow Industries entered a partnership with Fuxin Electronics, a company based in Guangdong Province, China in order to allow both companies to expand opportunities in the thermoelectric industry. TECHNOLOGY Marlow Industries designs and manufactures a range of semiconductor-based thermoelectric coolers and subsystems, which provide cooling, heating, temperature stabilization, and power generation. Its products are used for infrared sensors, fibre optic guidance systems, thermal reference sources, refrigerators and freezers. Marlow Industries’ thermoelectric materials and devices have been used by the Defence Advanced Research Projects Agency (DARPA) to enable the Department of Defence (DOD) thermal management systems to operate at lower temperatures with higher performance and longer lifetimeMarlow Industries secured a contract with NASA to develop and improve refrigerators it was using in the space station and other applications COMPANY STRUCTURES Marlow Industries is a subsidiary of II-VI Incorporated. It is headquartered in Dallas, Texas and has additional shared locations in China, Germany, Japan and Singapore. Executives:Fran Kramer, President and CEO of II-VIChuck Mattera, Vice President and General Manager, Compound Semiconductor Group, II-VI •	Raymond Marlow, Founder, Marlow Industries •	Barry Nickerson, General Manager, Marlow Industries •	Kevin MacGibbon, General Manager of Commercial Business, Marlow Industries and President, II-VI Vietnam

6.INPUT

The TEG is being heated on top side with the help of a hair dryer so as to increase the temperature while the bottom side is cool due to cold water.

OUTPUT The output is the electricity being produced due to the temperature difference being produced from TEG module. This reading is shown in multimeter and also the D.C. motor starts rotating. This is the output we get.

7.ADVANTAGES •	One of the greatest advantages of thermoelectric generators lies in the fact that they can derive their power from heat that would otherwise just dissipate into its surroundings. Unlike the case with a standard gasoline or diesel generator, purchasing fuel for a thermoelectric generator is unnecessary, as the generator can "steal" its fuel from any device or machine that creates and releases substantial amounts of heat. These devices can include ovens, burners and furnaces, as well as machines -- such as automobiles -- that produce heat as a by-product of creating power for other functions, such as propulsion. According to the University of the Pacific, "Thermoelectric generators help tap an unclaimed resource [heat] now considered waste." •	The thermoelectric modules that make up thermoelectric generators have solid-state constructions, which make the generators highly durable. "Solid-state" refers to the fact that the modules consist entirely of solid, fixed materials and do not rely on gases or vacuums. In contrast, other modules use tube construction, wherein they pass electrical currents through glass tubes filled with gasses or containing vacuums. Unlike tube modules, solid-state thermoelectric modules are robust and are not prone to cracking or shattering -- even when faced with turbulent conditions. As the University of the Pacific notes, thermoelectric generators' durability makes them "ideal for tasks in harsh environments such as automobiles, incinerators and spacecraft." DISADVANTAGES One of the main disadvantages of thermoelectric generators, which as of 2011 has prevented their adoption on a wider scale, lies in their cost. According to the University of the Pacific, a single thermoelectric module capable of producing 14 watts of electrical power costs approximately $100. The University of the Pacific notes that most thermoelectric generators have an average efficiency of 4 percent, which means the generators cannot pass on 96 percent of the energy they obtain from heat sources. According to Tufts University, a thermoelectric generator will only operate efficiently when supplying electrical current to a device that has a similar electrical resistance. For example, a 100-watt thermoelectric generator could theoretically power a 100-watt lightbulb efficiently but would ultimately waste energy if attempting to power a 30-watt bulb

8.APPLICATIONS Thermoelectric generators can be applied in a variety of applications. Usually, thermoelectric generators are used for small applications where heat engines (which are bulkier but more efficient) such as Stirling engines would not be possible. •	Many space probes, including the Mars Curiosity rover, generate electricity using a thermoelectric generator whose heat source is a radioactive element. For more details, see the article: Radioisotope thermoelectric generator. •	Cars and other automobiles produce waste heat (in the exhaust and in the cooling agents). Harvesting that heat energy, using a thermoelectric generator, can increase the fuel efficiency of the car. For more details, see the article: Automotive Thermoelectric Generators. •	In addition to in automobiles, waste heat is also generated in many other places, such as in industrial processes and in heating (wood stoves, outdoor boilers, cooking, oil and gas fields, pipelines, and remote communication towers). Again, the waste heat can be reused to generate electricity. In fact, several companies have begun projects in installing large quantities of these thermoelectric devices. Some companies include Sheetak Thermal Electronics Corp., Custom Thermoelectric, Marlow Industries, tecteg MFR., wellentech and TEG Power. Other companies are developing consumer-level applications to capture the energy commonly wasted during cooking. A handful of USB cooking pots have emerged, such as the Hatsuden Nabe thermoelectric cookpotStealth Power Systems, and the PowerPot. Wood stove TEG12VDC-24AIR and TEG12VDC-24LIQUID TEG Generators producing enough power to trickle charge 12VDC and 24VDC batteries. Thermal Electronics Corp. •	Microprocessors generate waste heat. Researchers have considered whether some of that energy could be recycled. (However, see below for problems that can arise.) •	Solar cells use only the high frequency part of the radiation, while the low frequency heat energy is wasted. Several patents about the use of thermoelectric devices in tandem with solar cells have been filed The idea is to increase the efficiency of the combined solar/thermoelectric system to convert the solar radiation into useful electricity

9.CONCLUSION Thermoelectric generators are an intriguing way to generate renewable energy directly from waste heat. However, their efficiencies are limited due to their thermal and electrical properties being dependent on each other. Nevertheless, their solid state scalable technology makes them appealing and even more efficient in selective applications. Implementing thermoelectric generators on vehicle exhaust manifolds would help reduce fuel consumption, which in turn would help preserve the world natural resources and reduce carbon emissions.

10	. REFERENCE

1.	http://www.nature.com/nature/journal/v489/n7416/full/nature11439.html 2.	http://www.thermoelectric-generator.com/ultra_high_temperature_teg_power_modules.htm 3.	http://www.engadget.com/2011/06/14/usb-power-pot-uses-excess-heat-to-charge-your-gadgets/ 4.	http://www.stealthpowersystems.com 5.	https://www.thepowerpot.com/press 6.	http://www.espressomilkcooler.com/complete_thermoelectric_generators_assemblies.htm/ 7.	http://engr.case.edu/leinweber_lawrence/eecs651/04.7_2_0715.pdfDOI: 10.1109/DATE.2008.4484669 8.	www.google .com 9.	Wikipedia – free encyclopedia