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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