By:- Prof- Chaudhari M.M(Dept. Of Mechanical Engg.)Nashik (Maharashtra)

Thermoelectric Generator

CONTENTS

IntroductionSeebeck effectThermoelectric materialThermoelectric generatorWorking principleFigure of meritAdvantagesDisadvantagesApplicationConclusionReferences

CONTENTS

• In recent years due to energy issues has brought in major interest to the research of advanced technology perticularly in I.C engines.

• The growing rate of population indicates that the energy demand is likely to increase substantial thermal energy available from exhaust gas in modern automotive engines.

• Two-third of the energy from combustion in vehicle is lost as waste heat.

• The 40 % lost energy is in the form of exhaust gas.

INTRODUCTION

HISTORY The pioneer in thermoelectrics was a German scientist Thomas Johann

Seebeck (1770-1831).

Thermoelectricity refers to a class of phenomena in which a temperature

difference creates an electric potential or an electric potential creates a

temperature difference.

Thermoelectric power generator is a device that converts the heat energy

into electrical energy based on the principles of Seebeck effect.

Later, In 1834, French scientist, Peltier and in 1851, Thomson (later Lord

Kelvin) described the thermal effects on conductors.

Seebeck effect

S= dV / dT;

In 1821, Thomas Seebeck found that an electric current would flow continuously in a closed circuit made up of two dissimilar metals, if the junctions of the metals were maintained at two different temperatures.

S is the Seebeck Coefficient with units of Volts per Kelvin

S is positive when the direction of electric current is same as the direction of thermal current

When the junctions of two different metals are maintained at different temperature, the emf is produced in the circuit This is known as Seebeck effect.

The conductor 1 is maintained at T+∆T temperature

The conductor 2 is maintained at temperature T

Since the junctions are maintained at different temperature, the emf ‘U’ flows across the circuit.

Cont.…..

•

Thermoelectric materialThe good thermoelectric materials

should possess

Large Seebeck coefficients

High electrical conductivity

Low thermal conductivity

Thermoelectric generator

Basic Working Principle

• A high electrical conductivity is necessary to minimize Joule heating and low thermal conductivity helps to retain heat at the junctions and maintain a large temperature gradient. These three properties were later put together and it is called figure-of-merit (Z).

• Figure of merit Z= α2 / k R

Figure of merit

• Environmental friendly• Recycles wasted heat energy• Scalability ,meaning that the device can be applied to

any size heat source from a water heater to a manufacturers equipment

• Reliable source of energy• Lowers production cost• Silent in operation• They are simple , compact and safe• They are not position dependent

Advantages

Low energy conversion efficiency rateSlow technology progressionLimited applicationsRequires Relatively constant heat sourceLack of customer/industry education

about thermoelectric generators

Disadvantage

The TEG is used to convert the waste heat emitted from jet engine, IC engine, furnace, heat water conveyor tubes.

For low power remote application. ( where bulkier heat engines would not be possible)

On gas pipelines for CATHODIC protection for example: global thermoelectric(CALGARA , CANADA) TELGEN (Russia)

Automotive TEGs

Applications

CONCLUSION

Thermoelectric material have both high electrical conductivity and low thermal conductivity

The output voltage increases with increase in temperature difference

Longitudinal model indicates performance improvement of TEG

• Dipak Patil,Dr.R.R.Arakerimath,“A review of thermoelectric generator for waste heat recovery from engine exhaust”,Int. Journal of research in aeronautical & mechanical engineering,Vol.1Issue.8,Dec 2013.

• Saniya Leblanc,“Thermoelectric Generators: linking material properties and systems engineering for waste heat recovery applications”,sustainable materials and technologies 1-2(2014) 26-35.

• S.L.Nadaf,P.B.Gangavati,“A Review on waste heat recovery and utilization from diesel engines”,Nadaf et al. Int. journal of advanced engineering technology E-ISSN 0976-3945.

• Prathamesh Ramade,Prathamesh Patil,Manoj Shelar,Sameer Chaudhary, Prof. Shivaji Yadav,Prof.Santosh Trimbake,“Automobile Exhaust thermo-electric generator design& performance analysis”,Int. journal of Emerging technology and advanced engineering,Vol.4,Issue5,may 2014.

• A.Jacks delightus Peter,Balaji.D,D.Gaurishankar,“waste heat energy harvesting using thermoelectric generator”,IOSR Journal of engineering(IOSRJEN) vol-3 Issue7(July-2013),PP 01-04.

REFERNCES

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