mitesh seminar

8/3/2019 Mitesh Seminar

1/26

P a g e | 1

1 | P a g e

INTRODUCTION TO THERMOELECTRIC COOLING AND THE

THERMOELECTRIC EFFECTS GOVERNING IT

French watchmaker, Jean Charles Athanase Peltier, discovered thermoelectric cooling effect, also

known as Peltier cooling effect, in 1834. Peltier discovered that the passage of a current through a

junction formed by two dissimilar conductors caused a temperature change. However, Peltier failed

to understand this physics phenomenon. Peltier effect was made clear in 1838 by Emil Lenz, a

member of the St. Petersburg Academy. Lenz demonstrated that water could be frozen when placed

on a bismuth-antimony junction by passage of an electric current through the junction.

In 1911 another scientist Altenkirch derived the basic theory of thermoelectrics. His work pointed out

that a thermoelectric cooling material needed to have high Seebeck coefficients, good electrical

conductivity to minimize Joule heating, and low thermal conductivity to reduce heat transfer from

junctions to junctions. Shortly after the development of practical semiconductors in 1950s, bismuth

telluride began to be the primary material used in the thermoelectric cooling.

THERMOELECTRIC EFFECTS SEEBECK EFFECT

To illustrate the Seebeck Effect let us look at a simple thermocouple circuit as shown in figure

below. The thermocouple conductors are two dissimilar metals denoted as Material x and Material y.

Fig 1.SEEBECK EFFECT

In a typical temperature measurement application, thermocouple A is used as a "reference" and is

maintained at a relatively cool temperature of Tc. Thermocouple B is used to measure the temperature

of interest (Th) which, in this example, is higher than temperature Tc. With heat applied to

thermocouple B, a voltage will appear across terminals T1 and T2.


2/26

P a g e | 2

2 | P a g e

PELTIER EFFECTIf we modify our thermocouple circuit to obtain the configuration shown in Figure (1.2), it will be

possible to observe an opposite phenomenon known as the Peltier Effect.

Fig 2.PELTIER EFFECT

If a voltage (Vin) is applied to terminals T1 and T2 an electrical current (I) will flow in the circuit. As

a result of the current flow, a slight cooling effect (Qc) will occur at thermocouple junction A where

heat is absorbed and a heating effect (Qh) will occur at junction B where heat is expelled. Note that

this effect may be reversed whereby a change in the direction of electric current flow will reverse the

direction of heat flow.

Joule heating, having a magnitude of I x R (where R is the electrical resistance), also occurs in the

conductors as a result of current flow. This Joule heating effect acts in opposition to the Peltier effect

and causes a net reduction of the available cooling.

THOMSON EFFECTWhen an electric current is passed through a conductor having a temperature gradient over its length,

heat will be either absorbed by or expelled from the conductor. Whether heat is absorbed or expelled

depends upon the direction of both the electric current and temperature gradient. This phenomenon,

known as the Thomson Effect, is of interest in respect to the principals involved but plays a

negligible role in the operation of practical thermoelectric modules.


3/26

P a g e | 3

3 | P a g e

SEMICONDUCTORS DOPING

N-TYPE SEMICONDUCTORS

N doped semiconductors have an abundant number of extra electrons to use as charge carriers.

Normally, a group IV material (like Si) with 4 covalent bonds (4 valence electrons) is bonded with 4

other Si. To produce an N type semiconductor, Si material is doped with a Group V metal (P or As)

having 5 valence electrons, so that an additional electron on the Group V metal is free to move and

are the charge carriers.

A figure showing doping of Arsenic in Silicon is shown here.

Fig 3.Arsenic dopant adds free electrons to crystalline silicon lattice, making it more electrically

conductive, thereby creating an N-type semiconductor.


4/26

P a g e | 4

4 | P a g e

P-TYPE SEMICONDUCTORS

For P type semiconductors, the dopants are Group III (In, B) which has 3 valence electrons; these

materials need an extra electron for bonding which creates holes. P doped semiconductors are

positive charge carriers. Theres an appearance that a hole is moving when there is a current applied

because an electron moves to fill a hole, creating a new hole where the electron was originally. Holes

and electrons move in opposite directions.

Fig4.Indium dopant creates free space to crystalline silicon lattice, thereby creating a P-type

semiconductor

As can be seen from above diagram, addition of Indium in Silicon structure leaves an empty space

where an electron should have been there. This space is called hole.


5/26

P a g e | 5

5 | P a g e

BASICS OF THERMOELECTRIC REFRIGERATION

REFRIGERATION USING n-TYPE SEMICONDUCTORA typical thermoelectric refrigeration component is shown. Bismuth telluride (a semiconductor),is

sandwiched between two conductors, usually copper. A semiconductor (called a pellet) is used

because they can be optimized for pumping heat and because the type of charge carriers within them

can be chosen. The semiconductor in this examples n-type (doped with electrons) therefore, the

electrons move towards the positive end of the battery.

The semiconductor is soldered to two conductive materials, like copper. When the voltage is applied

heat is transported in the direction of current flow.

Fig 5.A Schematic showing refrigeration process using n-type semiconductor

REFRIGERATION USING p-TYPE SEMICONDUCTORWhen a p-type semiconductor (doped with holes) is used instead, the holes move in a direction

opposite the current flow. The heat is also transported in a direction opposite the current flow and

in the direction of the holes. Essentially, the charge carriers dictate the direction of heat flow.

Fig 6.A Schematic showing refrigeration process using p-type semiconductor


6/26

P a g e | 6

6 | P a g e

These semiconductors are not actually diodes. It is easy to see why many people expect couples to

operate like diodes, given the pairing of P and N materials, but there is a crucial difference. In the

manufacturing of diodes, a depletion region is created between the immediately adjacent P and N

layers. When the diode is forward-biased, charge carriers are drawn into the depletion region and the

diode becomes conductive; when reverse-biased, charge carriers are drawn away from the depletion

region and the diode acts like an open circuit. Without a depletion region, a TE couple cannot act like

a diode; the couple will conduct in both electrical polarities and there is no fixed voltage drop across

the couple (unlike the nominal 0.6 to 0.7 VDC typically dropped across a forward-biased silicon

diode).

REFRIGERATION USING SEMICONDUCTORS IN SERIES AND PARALLELElectrons can travel freely in the copper conductors but not so freely in the semiconductor. As the

electrons leave the copper and enter the hot-side of the p-type, they must fill a "hole" in order to

move through the p-type. When the electrons fill a hole, they drop down to a lower energy level and

release heat in the process.

Then, as the electrons move from the p-type into the copper conductor on the cold side, the electrons

are bumped back to a higher energy level and absorb heat in the process. Next, the electrons move

freely through the copper until they reach the cold side of the n-type semiconductor.

When the electrons move into the n-type, they must bump up an energy level in order to move

through the semiconductor. Heat is absorbed when this occurs. Finally, when the electrons leave the

hot-side of the n-type, they can move freely in the copper. They drop down to a lower energy level

and release heat in the process.

To increase heat transport, several p type or n type thermoelectric (TE) components can be hooked up

in parallel. However, the device requires low voltage and therefore, a large current which is too great

to be commercially practical.


7/26

P a g e | 7

7 | P a g e

Fig 7.N-type semiconductors used in series for cooling purpose

The TE components can be put in series but the heat transport abilities are diminished because the

interconnectings between the semiconductors creates thermal shorting.

Fig 8.N-type semiconductors used in parallel to give cooling effect

REFRIGERATION USING BOTH TYPES OF SEMICONDUCTORS

The most efficient configuration is where a p and n TE component is put electrically in series but

thermally in parallel. The device to the right is called a couple. One side is attached to a heat source

and the other a heat sink that convects the heat away. The side facing the heat source is considered

the cold side and the side facing the heat sink the hot side.


8/26

P a g e | 8

8 | P a g e

Fig 9.Use of p and n type semiconductors together for cooling effect

Between the heat generating device and the conductor must be an electrical insulator to prevent an

electrical short circuit between the module and the heat source. The electrical insulator must also

have a high thermal conductivity so that the temperature gradient between the source and the

conductor is small. Ceramics like alumina are generally used for this purpose.

Fig 10.Conceptual drawing of air-to-air thermoelectric cooling system


9/26

P a g e | 9

9 | P a g e

Fig 11.A schematic of single module thermoelectric refrigerator with p & n type semiconductors

Semiconductors are the optimum choice of material to sandwich between two metal conductors

because of the ability to control the semiconductors charge carriers, as well as, increase the heat

pumping ability. The material is chosen based on a criterion called figure of merit, as explained

below.


10/26

P a g e | 10

10 | P a g e

FIGURE OF MERITThe figure of merit represents the quality of performance of a thermoelectric material, sometimes it is

multiplied by temperature. It is defined as:

Where is the electrical resistivity, k is the thermal conductivity, and is the Seebeck Coefficient.

Hence, low electrical resistivity and thermal conductivity are required for high figure of merit. These

values are temperature dependent as the figure of merit is temperature dependent. P and N type

material have different figures of merit and are averaged to determine a materials overall quality.

Plots of various p-type semiconductor figures of merit times temperature vs. temperature are shown.

Similar results are shown for n-type semiconductors.

Fig 12.zTfor p-type thermoelectric materials

kZ


11/26

P a g e | 11

11 | P a g e

Fig 13.zT for n-type thermoelectric materials

The most commonly used semiconductor for electronics refrigeration applications is Bi2Te3 because

of its relatively high figure of merit. However, the performance of this material is still relatively low

and alternate materials are being investigated with possibly better performance.

Alternative materials include:

Alternating thin film layers of Sb2Te3 and Bi2Te3. Lead telluride and its alloys SiGe Materials based on nanotechnology

Metals are used to sandwich the semiconductor. Because the TE performance is also dependent on

these materials, an optimal material must be chosen, usually copper.


12/26

P a g e | 12

12 | P a g e

HEAT SINK REQUIREMENT AND DESIGN CONSIDERATIONS

Whether heating or cooling a thermal load, some form of heat sink has to be employed to either

collect heat (in heating mode) or dissipate collected heat into another medium (e.g., air, water, etc.).

Without such provisions, the TE device will be vulnerable to overheating; once it reaches the reflow

temperature of the solder employed, the unit will be destroyed. When the heat sink is exchanging

heat with air, a fan is usually required, as well, to minimize the size of the sink required.

A heat sink is an integral part of a thermoelectric cooling system and its importance to total system

performance must be emphasized. Since all operational characteristics of TE devices are related to

heat sink temperature, heat sink selection and design should be considered carefully.

A perfect heat sink would be capable of absorbing an unlimited quantity of heat without exhibiting

any increase in temperature. Since this is not possible in practice, a heat sink is selected such that it

will have an acceptable temperature rise while handling the total heat flow from the TE device(s).

The definition of an acceptable increase in heat sink temperature necessarily is dependent upon the

specific application, but because a TE module's heat pumping capability decreases with increasing

temperature differential, it is highly desirable to minimize this value. A heat sink temperature rise of

5 to 15C above ambient (or cooling fluid) is typical for many thermoelectric applications.

Several types of heat sinks are available including natural convection, forced convection, and liquid-

cooled. Natural convection heat sinks may prove satisfactory for very low power applications

especially when using small TE devices operating at 2 amperes or less. For the majority of

applications, however, natural convection heat sinks will be unable to remove the required amount of

heat from the system, and forced convection or liquid-cooled heat sinks will be needed.

Heat sink performance usually is specified in terms of thermal resistance (Q):

Qs=

Ts - Ta

____________

Q


13/26

P a g e | 13

13 | P a g e

Where:

Qs = Thermal Resistance in Degrees C per Watt

Ts = Heat Sink Temperature in Degrees C

Ta =Ambient or Coolant Temperature in Degrees C

Q = Heat Input to Heat Sink in Watts

Each thermoelectric cooling application will have a unique heat sink requirement and frequently

there will be various mechanical constraints that may complicate the overall design. Because each

case is different, it is virtually impossible to suggest one heat sink configuration suitable for most

situations. We have several off the shelf heat sinks and liquid heat exchangers appropriate for many

applications but encourage you to contact our engineering department.

When using commercially available heat sinks for thermoelectric cooler applications, it is important

to be aware that some off-the-shelf units do not have adequate surface flatness. A flatness of 1mm/m

(0.001 in/in) or better is recommended for satisfactory thermal performance and it may be necessary

to perform an additional lapping, flycutting, or grinding operation to meet this flatness specification.

NATURAL CONVECTION HEAT SINKSNatural convection heat sinks normally are useful only for low power applications where very little

heat is involved. Although it is difficult to generalize, most natural convection heat sinks have a

thermal resistance (Qs) greater than 0.5C/watt and often exceeding 10C/watt. A natural convection

heat sink should be positioned so that (a) the long dimension of the fins is in the direction of normal

air flow, vertical operation improves natural convection and (b) there are no significant physical

obstructions to impede air flow. It also is important to consider that other heat generating components

located near the heat sink may increase the ambient air temperature, thereby affecting overall

performance.

FORCED CONVECTION HEAT SINKSWhen compared to natural convection heat sinks, substantially better performance can be realized as

far as the forced convection heat sinks are considered. That is the reason that they are the most

commonly found heat sinks in a thermoelectric refrigerator. The thermal resistance of quality forced

convection systems typically falls within a range of 0.02 to 0.5C/watt. Many standard heat sink

extrusions are available that, when coupled with a suitable fan, may be used to form the basis of a


14/26

P a g e | 14

14 | P a g e

complete cooling assembly. Cooling air may be supplied from a fan or blower and may either be

passed totally through the length of the heat sink or may be directed at the centre of the fins and pass

out both open ends. This second air flow pattern, illustrated in Figure, generally provides the best

performance since the air blown into the face of the heat sink creates greater turbulence resulting in

improved heat transfer. For optimum performance, the housing of an axial fan should be mounted a

distance of 8-20mm (0.31-0.75") from the fins. Other configurations may be considered depending

on the application.

Fig 14.Forced Convection Heat Sink System Showing Preferred Air Flow

The thermal resistance of heat sink extrusions often is specified at an air flow rate stated in terms of

velocity whereas the output of most fans is given in terms of volume.

LIQUID COOLED HEAT SINKSLiquid cooled heat sinks provide the highest thermal performance per unit volume and, when

optimally designed, can exhibit a very low thermal resistance. Although there are many exceptions,

the thermal resistance of liquid cooled heat sinks typically falls between 0.01 and 0.1C/watt. Simple

liquid heat sinks can be constructed by soldering copper tubing onto a flat copper plate or by drilling

holes in a metal block through which water may pass. With greater complexity (and greater thermal

performance), an elaborate serpentine water channel may be milled in a copper or aluminium block

that later is sealed-off with a cover plate. We offer several liquid-type heat sinks that may be used

advantageously in thermoelectric systems. With other commercial heat sinks, always check the

surface flatness prior to installation. While liquid cooling may be considered undesirable and/or

unsatisfactory for many applications, it may be the only viable approach in specific situations.


15/26

P a g e | 15

15 | P a g e

CALCULATION OF THERMOELECTRIC MODULE PERFORMANCEThere are five variable parameters applicable to a thermoelectric module that affects its operation.

These parameters include:

I - the input current to the module expressed in amperes

Vin - the input voltage to the module expressed in volts

Th - the hot side temperature of the module expressed in K

Tc - the cold side temperature of the module expressed in K

Qc - the heat input to (or heat pumped by) the module expressed in watts

In order to calculate module performance it is necessary to set at least three of these variables to

specific values. Two common calculation schemes involve either (a) fixing the values of Th, I, and

Qc or, (b) fixing the values of Th, I and Tc. For the computer-oriented individual, a relatively

straightforward calculation routine can be developed to incrementally step through a series of fixed

values to produce an output of module performance over a range of operating conditions.

SINGLE-STAGE MODULE CALCULATIONSThese equations mathematically describe the performance of a single-stage thermoelectric module as

illustrated in figure below. When entering numerical data, the temperature values must be expressed

in degrees Kelvin (K).

a) The temperature difference (DT) across the module in K or C is:

DT = Th - Tc


16/26

P a g e | 16

16 | P a g e

b) Heat pumped (Qc) by the module in watts is:

Qc = (SM x Tc x I) - (0.5 x I2

x RM) - (KM x DT)

c) The input voltage (Vin) to the module in volts is:

Vin = (SM x DT) + (I x RM)

d) The electrical input power (Pin) to the module in watts is:

Pin = Vin x I

e) The heat rejected by the module (Qh) in watts is:

Qh = Pin + Qc

f) The coefficient of performance (COP) as a refrigerator is:

COP = Qc / Pin

DESCRIPTION & MODELING OF CASCADE THERMOELECTRICMODULES

A standard single-stage thermoelectric cooling module is capable of achieving a

maximum no-load temperature differential (DTmax) of approximately 72C. It is

possible to obtain DTs of up to 130C by mechanically stacking modules on top of one

another whereby the cold side of one module becomes the hot side of another module

mounted above. This stacking arrangement is called a Cascade orMulti-Stage module

configuration. Cascade modules usually, but not always, have a pyramid shape thereby

the higher stages are physically smaller than those below. Regardless of the physical

shape, however, lower stages must always have greater heat pumping capacity than the

higher stages. Although cascade configurations of up to six and seven stages have been

constructed, practical cascade devices usually have from two to four stages.


17/26

P a g e | 17

17 | P a g e

The principal factor that limits cascade module performance is related to the

temperature dependent properties of the thermoelectric semiconductor materials. The

performance of Bismuth Telluride alloys used in most thermoelectric coolers generally

peaks near 70C and performance falls-off appreciably at lower temperatures.

Consequently, cascade modules exhibit a condition of diminishing returns where, as

successive stages are added, the increase in DT becomes smaller.

Performance Graph of a Typical Cascade Module

MODELING OF CASCADE MODULESModeling of cascaded or multi-stage thermoelectric coolers is somewhat more complicated than for

single-stage devices. With multi-stage coolers, the temperature between each stage is critically

important and module performance cannot be established until each interstage temperature value is

known. With a two-stage cooler only one interstage temperature must be determined but, as more

stages are added, the thermal analysis becomes increasingly complex. Manually calculating multi-

stage module performance is extremely laborious, yet with a computer, the required calculations can

be performed with little effort.

The most common method for computer-modeling cascade modules involves carrying out an

iterative series of performance calculations beginning with assumed interstage temperature values.


18/26

P a g e | 18

18 | P a g e

Using this technique, the performance of each stage is repeatedly calculated until the difference

between successive interstage temperature calculations becomes very small (typically 0.1C or less).

When this point is reached, each of the relevant module performance parameters can be ascertained.

Four and greater-stage modules may be modelled in a similar manner by expanding the three-stage

calculation routines to include terms for each additional stage. Calculations of the various parameters

should be performed in the order shown.

TWO-STAGE MODULE CALCULATIONSA typical two-stage thermoelectric module is illustrated in Figure (12-2). The

following new terms will be used in the module performance calculations:

TM12 is the interstage temperature between stages 1 and 2 in K

SM1 is the Seebeck coefficient of the 1st stage in volts/K

SM2 is the Seebeck coefficient of the 2nd stage in volts/K

RM1 is the resistance of the 1st stage in ohms

RM2 is the resistance of the 2nd stage in ohms

KM1 is the thermal conductance of the 1st stage in watts/KKM2 is the thermal conductance of the 2nd stage in watts/K

Figure (12-2)

a) The interstage temperature (TM12) in K is:

(0.5 x I2) x (RM2 + RM1) + (KM1 x Th) + (KM2 x Tc)

________________________________________________________________I

x (SM1 - SM2) + KM1 + KM2

TM12 =


19/26

P a g e | 19

19 | P a g e

b) Heat pumped (Qc) by the module in watts is:

Qc = (SM2 x Tc x I) - (0.5 x I2

x RM2) - (KM2 x (TM12 -Tc))

c) The input voltage (Vin) to the module in volts is:

Vin = (SM2 x (TM12 -Tc) + (I x RM2) + (SM1 x (Th - TM12)) + (I x RM1)

d) The electrical input power (Pin) to the module in watts is:

Pin = Vin x I

e) The heat rejected by the module (Qh) in watts is:

Qh = (SM1 x Th x I) + (0.5 x I2

x RM1) - (KM1 x (Th - TM12)

or

Qh = Qc - Pin

f) The coefficient of performance (COP) as a refrigerator is:

COP = Qc / Pin

Thus we can conclude that thermoelectric refrigerators performance depends on the following

factors:

The temperature of the cold and hot sides. Thermal and electrical conductivities of the devices materials. Contact resistance between the TE device and heat source/heat sink. Thermal resistance of the heat sink.


20/26

P a g e | 20

20 | P a g e

DRAWBACKS OF THERMOELECTRIC REFRIGERATORS

As the heat load increases, the advantages that thermoelectric cooling offer in comparison tocompressor systems diminishes. When evaluating on the basis of heat load alone, a

compressor system will likely be more cost effective when the heat load is greater than

approximately 200 W.

A common problem with TE refrigeration is that condensation may occur causing corrosionand eroding the TEs inherent reliability. Condensation occurs when the dew point is reached.

The dew point is the temperature to which air must be cooled at constant pressure for thewater vapor to start to condense Condensation occurs because the air loses the ability to carry

the water vapor that condenses. As the airs temperature decreases its water vapor carrying

capacity decreases. Since TE refrigerator can cool to low and even below ambient

temperatures, condensation is a problem. Because of this reason, sealants are used to protect

the chip from water. The most common sealant employed is silicon rubber.

Although this has been a concern for quite some time, another problem persists because of

sealants. While perimeter seals are an effective barrier to water and dust, they are not

impervious to vapour migration. Once the vapor gets into the module, it condenses and

becomes trapped. The seal is then an effective impediment to outflowing of the condensed

moisture. Thus the perimeter seal winds up compounding the problem, often accelerating the

corrosive effects of electrolysis. Modules often do better with no seal at all than with the usual

perimeter protection offered in the industry. Hence, companies provide an option to the

customer as far as sealants are concerned. They are rather sold as an accessory than as a

necessity.


21/26

P a g e | 21

21 | P a g e

WHY USE THERMOELECTRICS INSTEAD OF TRADITIONAL

REFRIGERANT-BASED SYSTEMS

Solid state designo No moving partso Integrated chip designo No hazardous gaseso Silent operation

Compact and lightweighto Low profileo No bulky compressor unitso Perfect for bench top applications

High reliabilityo 100,000 hours + Mean Time Between Failures (MTBF)

Precise temperature stabilityo Tolerances of better than +/- 0.1Co Accurate and reproducible ramp and dwell times

Cooling/heating mode optionso Fully reversible with switch in polarityo Supports rapid temperature cycling


22/26

P a g e | 22

22 | P a g e

Localized Coolingo Spot cooling for components or medical applicationso Perfect for temperature calibration in precision detection systems

Rapid response timeso Instantaneous temperature change

Low DC voltage designs

Dehumidificationo Efficient condensation of atmospheric water vapour


23/26

P a g e | 23

23 | P a g e

SAFETY ISSUES WITH THERMOELECTRIC REFRIGERATORS

There are two areas of concern here. First, neverpower up a Peltier device unless at least oneside is mounted to a suitable heat sink. Suitable means that it can at least handle the wattage

dissipated by the devicenot some little sink made for a small transistor package. A typical

Peltier device may dissipate 60 W or more internally. The hot side of a thermoelectric device

can get hotterand fasterwhen it is not mounted to a proper sink. This is not just a safety

issue, a device powered without proper sinking, can destroy itself very quickly.

The other safety concern is electrical. Although the electrical hazard potential associated withmost thermoelectric systems is very small, there are some issues which deserve attention.

Typically, Peltier devices are mounted to either aluminium or copper hardware (sinks, liquid

heat exchangers, etc.). It ispossible, therefore, for debris or moisture to create a short-circuit

condition between the hardware and an electrically-live part of the Peltier device. It is up to

the designer, therefore, to prevent such a problematic condition from occurring. From a safety

standpoint, it is highly recommended that designers employ DC power which is fully-isolated

and properly fused. The use of autotransformers or direct wiring to an AC service line is

generally not recommended; if employed, a ground fault interrupter should be included in the

design.


24/26

P a g e | 24

24 | P a g e

APPLICATIONS OF THERMO-ELECTRIC REFRIGERATORS

Hotel room (mini-bar) refrigerators

Refrigerators for mobile homes, trucks, recreational vehicles and cars

Portable picnic coolers; wine coolers; beverage can coolers

Drinking water coolers. Medical chillers.

Other potential future applications include domestic and commercial refrigerators andfreezers, and mobile refrigeration and cooling systems.


25/26

P a g e | 25

25 | P a g e

CONCLUSION

By this report, we get an insight of the world of thermoelectric refrigerators which are the future

because it offers a convenient, earth friendly alternative to normal refrigeration systems. These

refrigerators only have the disadvantage of having lower COP than conventional refrigerators, which

is where the future research lies. Research is going on to not only improve the efficiency but also

reduce their cost and maximize electricity output for given heat source by changing the materials

used in construction. All and all, it seems to be of great potential and it can be the future in coming

years.


26/26

P a g e | 26

REFERENCES

http://en.wikipedia.org/wiki/Thermoelectric_effect

http://www.tellurex.com/technology/peltier-faq.php

http://www.ferrotec.com/technology/thermoelectric/

http://www.tetech.com/FAQ-Technical-Information.html

http://www.customchill.com/index.php

S. Kaka, H. F. Smirnov, M. R. Avelino, June 2003, Low Temperature andCryogenic Refrigeration, Springer publishers, Netherlands, pp.30-37
http://en.wikipedia.org/wiki/Thermoelectric_effecthttp://en.wikipedia.org/wiki/Thermoelectric_effecthttp://www.tellurex.com/technology/peltier-faq.phphttp://www.ferrotec.com/technology/thermoelectric/http://www.tetech.com/FAQ-Technical-Information.htmlhttp://www.tetech.com/FAQ-Technical-Information.htmlhttp://www.ferrotec.com/technology/thermoelectric/http://www.tellurex.com/technology/peltier-faq.phphttp://en.wikipedia.org/wiki/Thermoelectric_effect

mitesh seminar

Documents