112522853 Thermoelectric Gentr(1)

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By: Amit DwivediAlok Negi

Abhishek BhattAmit Saini

PROJECT REPORT

ON UTILIZ TION OF W STE

HE T IN UTOMOBILES

USING THERMO ELECTRIC

GENER TOR



INTRODUCTION

Thermo electric generator (TEG) is a highly

sophisticated device which converts heat energy

into electricity energy by using the Seebeckeffect.. One promising idea is to use a solid-state

device called a thermoelectric generator (TEG) to

convert waste heat directly into electricity. This

would reduce the load on the vehicle's alternator

and thus vehicle economy can be increased.





OPERATION PRINCIPLES

In TEGs, thermoelectric materials are packed between the hot-side and the cold-side heat exchangers. The thermoelectricmaterials are made up of p-type and n-type semiconductors.

The temperature difference between the two surfaces of thethermoelectric module(s) generates electricity using theSeebeck Effect. When hot exhaust from the engine passesthrough an exhaust TEG, the charge carriers of thesemiconductors within the generator diffuse from the hot-sideheat exchanger to the cold-side exchanger. The build-up ofcharge carriers results in a net charge, producing anelectrostatic potential while the heat transfer drives a current.With exhaust temperatures of 700°C (~1300°F) or more, thetemperature difference between exhaust gas on the hot sideand coolant on the cold side is several hundred degrees. Thistemperature difference is capable of generating 500-750 W ofelectricity.



SEEBECK EFFECT



TEG PRODUCES ELECTRICAL POWER WHEN A

TEMPERATURE DIFFERENCE IS MAINTAINED BETWEEN

THE HOT AND COLD JUNCTIONS OF THE

THERMOELECTRIC MATERIALS

A thermocouple is formed by a

P type and an N type

thermoelectric element joined

together electrically by a hot

junction electrode. Adjacentthermocouples are joined

together electrically by cold

junction electrodes.





SYSTEM COMPONENTS OF TEG

A thermoelectric generator requires

the following components :

Support structure

Hot Sink

Module

Cold sink (Radiator)

Power Circuit



SUPPORT STRUCTURE

It is the part of the thermoelectric generator

where the thermoelectric modules are located.

The internal part of this structure normally ismodified in order to absorb the most part of the

heat accumulated in the exhaust gases.



MODULE SELECTION

A high temperature Bismuth telluride module has

been selected due to its high efficiency and high

operating temperature.



COLD SINK SELECTION

Cold sink is the second most important

component of the system.

Cold sink must dissipate large amount of heat

coming through the module and remain at the

low temperature.

Fan cooling may be necessary where maximum

power or compactness are desired.



COOLANT ARRANGEMENT TO CREATE

TEMPERATURE DIFFERENCE IN TEG

(WATER COOLED)



FLOW OF COOLANT IN TEG



3-D DESIGN OF TEG



OUR MODEL DESIGN AND

SPECIFICATION

Specifications

Length -240mm

Breadth -179mm

Height-162mm

Material used for fabrication :

Heat exchanger- stainless steel

Corrosion resistant ,resistant to wear & tear,

can withstand high temperature without

deformation, cheap as compared to other

materials



Insulation - aluminium-backed high-temperature glass fibre

Easy avaibility, thermal conductivity is very good above 500K,

electrical insulator, maximum service temperature of about

1500K

Wiring – copper

Good conductor of electricity 401W/mK, high melting point

(1358K), can be drawn into fine wire

Thermoelectric module- Si-Ge, Pb-Te

Si-Ge : Operating temperature difference 673K - 1073K

Pb-Te :Operating temperature difference 373K- 673K



Pumps- exhaust & coolant pumps

The pump at exhaust outlet is used to overcome

the back pressure produced by the sudden

restriction at various cross-sections and the

pump at coolant side is used to maintain

constant flow of water from radiator to TEG heat

exchanger

Pipes housings - stainless steel



ASSEMBLED MODEL



FUTURE SCOPE AND

APPLICATIONS

The T.E.G setup being able to utilize the waste

heat of automobile has a great future ahead. This

setup is most advantageous in case of powerplants.

In case of an automobile the T.E.G setup could be

able to produce enough energy that it can

completely replace the alternator. Besides T.E.Gsetup can also increase the fuel economy (by 5-

8%) and finally the overall efficiency of an

automobile.



For ships carrying large amount of diesel fuel and

operating on diesel power cycle. The T.E.G setup

would be quite beneficial. The electricity

produced by extracting heat from it’s exhaust canbe easily used for onboard electrical supply.

In future if we are able to find some materials

which can work more efficiently at low

temperature difference, or whose conversionefficiency is very high. Such materials can be

easily installed in our design by just increasing

the number of whirl leafs and thus more power

can be generated which would be enough to

replace the alternator.



BMW PROVIDES AN UPDATE ON WASTE HEAT

RECOVERY PROJECTS :THERMOELECTRIC

GENERATOR

TEG integrated in the exhaust manifold

TEG integrated into the

exhaust gas recirculation system

The two alternative systems developed to date

differ in their positioning in the vehicle—one unit

is designed for the exhaust system, while the

other is intended for the exhaust gas recirculation

system. The engineers of the BMW Groupbasically refined a technology that has been used

to power space probes for more than four

decades by NASA, the aeronautics and space

agency of the United States. The latest

generation of TEGs installed in the exhaust are

capable of generating 600 watts of electricalpower, and it will not be long before the goal of

1,000 watts is reached as research progresses.

The current prototype—a BMW X6—was built as

part of a development project funded by the US

Department of Energy.



VOLKSWAGEN SHOWS

THERMOELECTRIC GENERATOR FOR

WASTE HEAT R ECOVERY

Volkswagen claims 600W output from the TEG

under highway driving condition. The TEG-

produced electricity reportedly meets around30% of the car’s electrical requirements,

resulting in a reduced mechanical load

(alternator) and a reduction in fuel consumption

of more than 5%.



112522853 Thermoelectric Gentr(1)

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