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8/14/2019 cpm ppt.pptx

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Presented by

CHANDRA PRAKASH MAURYA


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finition Refrigerationis a process in which work is done to

move heat from one location to another.

Thermoelectric Refrigerationaims at providingcooling effect by using thermoelectric effects ratherthan the more prevalent conventional methods likethose using the vapour compression cycle or the gas

compression cycle.


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THERMOELECTRICEFFECTS

SEEBECK EFFECT:-

The Seebeck effect is theconversion of temperaturedifferences directly intoelectricity

Seebeck discovered that acompass needle would bedeflected when a closed loop

was formed of two metalsjoined in two places with atemperature differencebetween the junctions


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THERMOELECTRIC EFFECTS

THOMSON EFFECT:-

It describes the heating or

cooling of a current-carrying conductor with atemperature gradient.


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THERMOELECTRIC EFFECTSPELTIER EFFECT The Peltier effect bears the name of

Jean-Charles Peltier, a French physicistwho in 1834 discovered the calorificeffect of an electric current at the

junction of two different metals.

When a current is made to flowthrough the circuit, heat is evolved at

the upper junction (at T2), andabsorbed at the lower junction (at T1).The Peltier heat absorbed by the lower

junction per unit time, is equal to


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THERMOELECTRIC EFFECTSJOULEAN EFFECT

Joule made a careful studyof the heat produced by an

electric current. From thisstudy, he developedJoule'slaws of heating, the firstof which is commonlyreferred to as theJouleeffect. Joule's first lawexpresses the relationshipbetween heat generated ina conductor and currentflow, resistance, and time
http://en.wikipedia.org/wiki/Joule's_lawshttp://en.wikipedia.org/wiki/Joule's_lawshttp://en.wikipedia.org/wiki/Joule's_lawshttp://en.wikipedia.org/wiki/Joule's_laws


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HOW DOES TER WORKS? The most efficientconfiguration is where a pand n TE component is putelectrically in series butthermally in parallel . Thedevice to the right is called acouple.

One side is attached to aheat source and the other aheat sink that convects the

heat away. The side facing the heat

source is considered thecold side and the side facingthe heat sink the hot side.


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THERMOELECTRIC MODULE In practical use, couples are combined in a module

where they are connected electrically in series, andthermally in parallel.

a module is the smallest component commerciallyavailable. Modules are available in a great variety ofsizes, shapes, operating currents, perating voltages andranges of heat pumping capacity.

The present trend, however, is toward a larger numberof couples operating at lower currents. The user canselect the quantity, size or capacity of the module to fitthe exact requirement without paying for excess power.


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Thermoelectric Module

Construction1. Regular matrix of

TE elements

2. Ceramic plates

3. Electric

conductors4. Solders


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ANALYSIS OF THERMOELECTRIC

REFRIGERATION. COEFFICIENT OF PERFORMANCE

The Coefficient of Performance of the system as a

refrigerating device is defined as-C.O.P. = QO/ W

RI)T-)(T-(

RI21-)T-U(T-I)T-(C.O.P.

201np

201Onp


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COEFFICIENT OF PERFORMANCE

where,

From above equation we see that the performance of a thermoelectric

cooling system is a function of the parameter ZTm, where Z is called the

figure of merit. Z has units of reciprocal of temperature.

ANALYSIS OF THERMOELECTRIC REFRIGERATION

1ZT1

T

TZT1

T-T

T

C.O.P.m

0

1

m

01

0

max

UR

)-(

Z

2np

2

TTT

01

m


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Typical Temperature Profile Acrossa TE system


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ADVANTAGES:-There is ease of interchanging the cooling and heating functions byreversing the direction of current in the thermocouple

Thermoelectric systems are vibration less and have no moving parts.

Hence there is no problem of wear and noise.

There is no problem of containment and pollution because norefrigerant or chemical is used.

Since there is no bulky equipment it provides ease of miniaturization

for small capacity systems.

The capacity can be controlled easily by varying the current and hence

the amount of heat absorbed or evolved at the junctions.

The system is highly reliable ( with a life of > 250,000 hours)

This system also has the capacity to operate under various values of

gravity (including zero gravity) and in any position.


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unavaibility of suitable materialtotal cost of refrigeration is higher as

compare to other refrigeration systemefficiency of ter is less

its overall cop is in order to 0.1 to 0.2

power consumption is also high

DISADVANTAGES :-


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thermoelectrics and thermoelectric

cooling are being studied

exhaustively for the past several years

and various conclusions have been

conceived regarding the efficient

functioning of thermoelectric

refrigerators

CONCLUSIONS


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Military/Aerospace

Consumer Products

Laboratory and Scientific EquipmentLaboratory and Scientific Equipment

Industrial Equipments

Miscellaneous

APPLICATION OF TER IN THE REAL WORLD