1

Chapter 1

INTRODUCTION

1.1 HISTORY

Refrigeration is a process in which work is done to move heat from one location

to another. The work of heat transport is traditionally driven by mechanical work,

but can also be driven by heat, magnetism, electricity, laser, or other means.

Refrigeration has many applications, including, but not limited to:

household refrigerators, industrial freezers, cryogenics, and air conditioning. Heat

pumps may use the heat output of the refrigeration process, and also may be

designed to be reversible, but are otherwise similar to refrigeration units.

The first important discovery relating to thermoelectricity occurred in 1823 when

a German scientist, Thomas Seebeck, found that an electric current would flow

continuously in a closed circuit made up of two dissimilar metals provided that the

junctions of the metals were maintained at two different temperatures. Some 12

years later French watchmaker, Jean Charles Athanase Peltier, discovered

thermoelectric cooling effect, also known as Peltier cooling effect, Peltier

discovered that the passage of a current through a junction formed by two

dissimilar conductors caused a temperature change. The true nature of Peltier

effect was made clear by Emil Lenz in 1838, Lenz demonstrated that water could

be frozen when placed on a bismuth –antimony junction by passage pf an electric

current through the junction.

He also observed that if the current was reversed the ice could be melted. In 1909

and 1911 Altenkirch give the basic theory of thermoelectric. His work explained

those thermoelectric cooling materials 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. In 1949 Loffe

developed theory of semiconductors thermo elements and in 1945 Goldsmid and

Douglas demonstrated that cooling from ordinary ambient temperatures down to

below 0°C was possible Rowe [1]. Shortly after the development of practical

semiconductors in 1950’s, Bismuth Telluride began to be the primary material

used in the thermoelectric cooling.

2

Thermoelectric cooling works on the principle of Peltier effect, when a direct

current is passed two electrically dissimilar materials heat is absorbed or liberated

at the junction. The direction of the heat flow depends on the direction of applied

electric current and relative Seebeck coefficient of the two materials. A Peltier

module or thermoelectric module (Fig.1.) is a solid-state active heat pump which

consists a number of p- and n- type semiconductor couples connected electrically

in series and thermally in parallel are sandwiched between two thermally

conductive and electrically insulated substrate.

Conventional cooling systems such as those used in refrigerators utilize a

compressor and a working fluid to transfer heat. Thermal energy is absorbed and

released as the working Fluid undergoes expansion and compression and changes

phase from liquid to vapor and back respectively. Semiconductor thermoelectric

coolers (also known as Peltier coolers) offer several advantages over conventional

systems. They are entirely solid-state devices, with no moving parts; this makes

them rugged, reliable, and quiet. They use no ozone depleting

chlorofluorocarbons, potentially offering a more environmentally responsible

alternative to conventional refrigeration. They can be extremely compact, much

more so than compressor-based systems. Precise temperature control (< ± 0.1 °C)

can be achieved with Peltier coolers. However, their achieved with Peltier coolers.

However, their efficiency is low compared to conventional refrigerators. Thus,

they are used in niche applications where their unique advantages outweigh their

low efficiency. Although some large-scale applications have been considered (on

submarines and surface vessels), Peltier coolers are generally used in applications

where small size is needed and the cooling demands are not too great, such as for

cooling electronic components.

The thermoelectric cooling systems having advantages of lightweight, reliable,

noiseless, portable and uses electrons rather than refrigerant as a heat carrier, and

is feasible for outdoor purpose in cooperation with solar PV cells. Thermoelectric

coolers will either heat or cool depending upon the polarity of the applied DC

power. This feature eliminates the necessity of providing separate heating and

cooling functions for a given enclosed space. Xi et al. [4] presented in their study

that thermoelectric refrigeration emerges as alternative green refrigeration

technology due to no moving parts, reliable. Potable and compatible with Solar

PV cell generated DC power, making them complete environment friendly.

3

Fig. 1.1 Seebeck Effect

Fig.1.2 Peltier Effect

When a Current (I) is made to flow through the circuit, heat is evolved at the upper junction (T 2) and absorbed at the lower junction (T 1). The Peltier heat absorbed by the lower junction per unit time ∅ is equal to

∅ = π ABI

Where π AB is the Peltier coefficient.

4

1.2 APPLICATIONS Electronic

Medical

Aerospace

Telecommunications

Commercial

Military

Submarines

1.3 ADVANTAGES Eco-friendly

Compact Size

Light Weight

Lower Price

Less Consumption of Energy-

1.4 BLOCK DIAGRAM AND DESCRIPTION

Fig. 1.3 Principle of Peltier Effect

5

Fig. 1.4 Block Diagram of Thermoelectric Refrigeration System

Two unique semi-conductors, one n-type and one p-type, are used because they

need to have different electron densities. The semi-conductors are placed

thermally in parallel to each other and electrically in series and then joined with a

thermally conducting plate on each side. When a voltage is applied to the free

ends of the two semiconductors there is a flow of DC current across the junction

of the semi-conductors causing a temperature difference. The side with the

cooling plate absorbs heat which is then moved to the other side end of the device

where the heat sink is. TECs are typically connected side by side and sandwiched

between two ceramic plates. The cooling ability of the total unit is then

proportional to the number of TECs in it.

Thermoelectric refrigeration replaces the three main working parts with: a cold

junction, a heat sink and a DC power source. The refrigerant in both liquid and

vapor form is replaced by two dissimilar conductors. The cold junction

(evaporator surface) becomes cold through absorption of energy by the electrons

as they pass from one semiconductor to another, instead energy absorption by the

refrigerant as it changes from liquid to vapor. The compressor is replaced by a DC

power source which pumps the electrons from one semiconductor to another. A

6

heat sink replaces the conventional condenser fins, discharging the accumulated

heat energy from the system. The difference between two refrigeration methods,

then, is that a thermoelectric cooling system refrigerates without use of

mechanical devices, except perhaps in the auxiliary sense, and without refrigerant.

1.5 THERMOELECTRIC MODULE PERFORMANCES

This section provides a basic understanding of the performance of a

thermoelectric module. Thermoelectric heat pumping (Peltier effect) at the cold

end of a thermal couple, as shown in Figure 1, is given by

Qsb = αΙTc (1)

The term α is the average Seebeck coefficient of the thermoelectric material. It is

seen from this relation that heat is pumped when current flows through the couple.

However, the heat pumped may include other unwanted heat sources. These heat

sources are described in the following sections.

Joule heat: Current flow generates resistive or Joule heating (QJ) in the

thermoelectric material. It can be shown that 50 per cent of the Joule heat goes to

the cold end and 50 per cent goes to the hot end. The Joule heating is given by

Qj = Ι²R (2)

Where, R is the resistivity of the couple.

Conducted heat: During operation, heat is conducted from the hot end to the

cold end through the thermoelectric material. The rate of heat conduction is given

by

Qcd = K(Th - Tc) = KΔT (3)

Where, K is the thermal conductivity of thermocouple.

7

Equation (3) shows that Qcd increases with the temperature difference across the

couple.

Combining Equations (1), (2), and (3) into an energy balance at the end of the

thermoelectric couple gives the following:

Qc = Qsb – 0.5Qj – Qcd = αΙTc - 0.5Ι²R – KΔT (4)

Equation (4) is the standard equation of thermal module performance. This

equation shows that a thermoelectric module no longer operates (Qc=0) when the

sum of one half the Joule heat (0.5QJ) and the conducted heat (Qcd) equals the

Peltier heat (Qsb).

The electrical energy consumption of the couple is given by

Qe = Ι²R + αΙΔT (5)

Equation (5) shows that the electrical power consumption of a thermoelectric

couple is used to generate the Joule heat and overcome the Seebeck effect, which

generates power due to the temperature difference between the two junctions of

the couple.

The COP of the thermoelectric module for cooling is given by

ε = Qc / Qe

=αITc−k ∆ T−0.5 I ² R

I ² R+αIΔT(6)

It is seen that the COP is a function of the material dimension property of

thermocouple, the temperature of the hot side and cold side Th, Tc and the current

input. There exists an optimum current for maximum COP, if Th, Tc, and

thermoelectric material are fixed.

Solving the equation ∂ε/∂I = 0, the optimum current for the maximum (optimum)

COP can be given by

I opt = α ∆ T

R

√(1+ZTm )−1(7)

(7)

8

Replacing I in Equation (6) by Iopt, the optimum COP can be given by

ε opt=Tc(√1+ZTm−Th

Tc)

(Th−Tc)(√1+ZTm+1)(8)

Where

Tm = ½ (Th+Tc) (9)

Z = α²/ kR (10)

It is seen that the optimum COP under the optimum current is a function of Th, Tc

and the figure of merit of thermoelectric material.

1.6 HEAT TRANSFER MODEThe typical heat exchanger thermal resistance for a 45×45 mm square

thermoelectric module is:

1) Natural convection: 0.853-13.075m²K kW−1, depending on the fin density

and the ratio of the heat exchanger base plate area to the thermoelectric

module area. Higher ratios of the heat exchanger base plate area to the

thermoelectric module area result in a lower thermal resistance;

2) Forced air convection: 0.531-5.759m²K kW−1 , depending on the air flow

rate. Larger air flow rate result in a lower thermal resistance;

The data provided by Melcor shows the typical allowances of temperature

difference between the hot side and ambient, with respect to the heat exchange

mode. That is:

1) Natural convection: 20-40°C;

2) Forced air convection: 10-15°C

9

Chapter 2

COMPONENTS

2.1 THERMOELECTRIC REFRIGERATION SYSTEM

The thermoelectric refrigerator consists of the following components:

i. The thermoelectric module:The thermoelectric module consists of pairs of P- type and N- type semi-

conductor thermo element electrically in series and thermally in parallel.

The modules are considered to be highly reliable components due to their

solid state construction. For most application they will provide long,

trouble free service. In cooling application, an electrical current is supplied

to the module, heat is pumped from one side to the other, and result is that

one side of the module becomes cold and the other side hot [6].

Fig.2.1 Peltier Module

Fig.2.2 constructional detail of Peltier Module

10

The properties of a 31 couple, 9A Bismuth Telluride module [8] are:

Seebeck coefficient (α m) = 0.01229 V/k

Module thermal conductance (Km) = 0.1815 W/k

Module resistance (Rm) = 0.344Ω

ii. Heat sink:The heat sink usually made of aluminum, is in contact with the hot side of

a thermoelectric module. When the positive and negative module leads are

connected to the respective positive and negative terminals of a Direct

Current (D. C.) power source, heat will be rejected by the module’s hot

side, the heat sink expedites the removal of heat. Heat sink typically is

intermediates stages in the heat removal process whereby heat flows into a

heat sink and then is transferred to an external medium. Common heat

sinks include free convection, forced convection and fluid cooled,

depending on the size of the refrigerator.

Fig.2.3 CPU heat sink with fan attached

iii. Cold slide:The cold side also made of aluminum is in contact with the cold side of a

thermoelectric module, when the positive and negative module leads are

connected to the respective positive and negative terminals of a direct

current (D. C.) power source, heat will be absorbed by the module’s cold

side. The hot side of a thermoelectric module is normally placed in contact

with the object being cold.

11

iv. Power source:Thermoelectric module is a Direct Current (D.C.) device. Specified

thermoelectric module performance is valid if a Direct Current (D. C.)

Power supply is used. Actual D. C. power supply has a rippled output.

This D. C. component is detrimental [7]. Degradation of thermoelectric

module performance due to the ripple can be approximately by [7]:

∆ T Max

∆ T Max =

1

1+N ²2

v. Thermoelectric coolers:The thermo-electric module (40x40 mm) allows the temperature below

63°C at 25 W of dissipated power and the outer temperature of 25°C. It

provides the lowest temperature than alternative fans and radiators. For

normal work of this cooler it's necessary to provide 5 V and 1.5A

(maximum).The fan for this cooler require 12V and 0,1A (maximum). The

fan parameters: ball-bearing, 47,5mm, 65000 hours, 26 decibel. The whole

size of the cooler is 25x25x28,7mm.

Fig.2.4 Cooling fan

12

vi. Transformer:Two coils are wound over a Core such that they are magnetically

coupled. The two coils are known as the primary and secondary

windings.

In a Transformer, an iron core is used. The coupling between the coils

is source of making a path for the magnetic flux to link both the coils.

A core as in fig.2 is used and the coils are wound on the limbs of the

core. Because of high permeability of iron, the flux path for the flux is

only in the iron and hence the flux links both windings. Hence there is

very little ‘leakage flux’. This term leakage flux denotes the part of the

flux, which does not link both the coils, i.e., when coupling is not

perfect. In the high frequency transformers, ferrite core is used. The

transformers may be step-up, step-down, frequency matching, sound

output, amplifier driver etc. The basic principles of all the transformers

are same.

Fig.2.5 schematic diagram of transformer

13

Fig.2.6 single phase transformer

vii. Digital temperature control device:It displays the temperature on four 7-segment displays in the range of -

55◦C to +125◦C. At the heart of the circuit is the microcontroller AT

89S8252, which controls all its functions IC DS1821 is used as

temperature sensor.

Fig.2.7 digital temperature control device

viii. Capacitor:It is an electronic component whose function is to accumulate charges and

then release it.

To understand the concept of capacitance, consider a pair of metal plates

which all are placed near to each other without touching. If a battery is

connected to these plates the positive pole to one and the negative pole to the

other, electrons from the battery will be attracted from the plate connected to

the positive terminal of the battery. If the battery is then disconnected, one

plate will be left with an excess of electrons, the other with a shortage, and a

14

potential or voltage difference will exists between them. These plates will be

acting as capacitors. Capacitors are of two types: - (1) fixed type like

ceramic, polyester, electrolytic capacitors-these names refer to the material

they are made of aluminium foil. (2) Variable type like gang condenser in

radio or trimmer. In fixed type capacitors, it has two leads and its value is

written over its body and variable type has three leads. Unit of measurement

of a capacitor is farad denoted by the symbol F. It is a very big unit of

capacitance. Small unit capacitor are pico-farad denoted by pf

(Ipf=1/1000,000,000,000 f) Above all, in case of electrolytic capacitors, it's

two terminal are marked as (-) and (+) so check it while using capacitors in

the circuit in right direction. Mistake can destroy the capacitor or entire

circuit in operational.

Fig.2.8 capacitor

15

2.2 DEVELOPMENT IN THERMOELECTRIC COOLING SYSTEM

Min et al. [6] developed a number of prototype thermoelectric domestic-

refrigerators with different heat exchanger combination and evaluated their

cooling performances in terms of the COP, heat pumping capacity, cooling down

rate and temperature stability. The COP of a thermoelectric refrigerator is found to

be 0.3-0.5 for a typical operating temperature of 5oC with ambient at 25oC. The

potential improvement in the cooling performance of a thermoelectric refrigerator

is also investigated employing a realistic model, with experimental data obtained

from this work. The results show that an increase in its COP is possible through

improvements in module contact resistances, thermal interfaces and the

effectiveness of heat exchangers.

Adeyanju et al. [10] carried out a theoretical and experimental analysis of a

thermoelectric beverage chiller. Comparison were also made between the

hermoelectric beverage chiller’s cooling time with cooling times obtained from

the freezer space and cold space of a household refrigerator. The result shows that

for the refrigerator freezer space, the temperature of the water decreased linearly

with increasing time and for thermoelectric beverage chiller the temperature of the

water decreased exponentially with increasing time.

Lertsatitthanakorn et al. [11] evaluated the cooling performance and thermal

comfort of a thermoelectric ceiling cooling panel (TE-CCP) system composed of

36 TEM. The cold side of the TEM was fixed to an aluminum ceiling panel to

cool a test chamber of 4.5 m3 volume, while a copper heat exchanger with

circulating cooling water at the hot side of the TE modules was used for heat

release. Thermal acceptability assessment was performed to find out whether the

indoor environment met the ASHRAE Standard-55’s 80% acceptability criteria.

The standard was met with the TE-CCP system operating at 1 A of current flow

with a corresponding cooling capacity of 201.6 W, which gives the COP of 0.82

with an average indoor temperature of 27oC and 0.8 m/s indoor air velocity.

16

Chapter 3

PROJECT

3.1 HEAT SINK DESIGNIn order to visualize the energy flow in the entire system, a thermal circuit is

constructed, which is schematically shown in Figure 2. Rc and Rh and are the

overall thermal resistances for the internal heat sink and external heat sink,

respectively. The components of the air cooler are an internal heat sink, a

thermoelectric module, and an external heat sink as shown in Figure 2 is the

amount of heat transported at the internal heat sink, which is actually the design

requirement (33 Watts).

Fig.3.1 prototype of thermoelectric cooling system

17

Fig.3.2 heat sink

Fig.3.3 circuit diagram of TEC

Fig.3.4 Common heat exchanger designs: (a) natural air convection, (b) forced air convection.

18

3.2 GEOMETRY

Two main geometries were considered for the device the first was a rectangle. The

advantage of rectangle is its simplicity to build and insulate. A door can easily be

attached to one of the sides. Finally any insulation, thermoelectric modules or heat

sinks are easily fastened to the sides. The second choice for cooler geometry was a

cylinder. The advantage found with this shape is that it has the largest volume to

surface area ratio of the two designs considered. This is a good property when the

objective is to minimize heat loss. But considering the simplicity to build and

insulate rectangle box is considered.

The geometry of the project is given below:

Outer dimension = 30 cm ×27 cm ×38 cm

Internal dimension = 28.5 cm ×25.5 cm× 36.5 cm

3.3 MATERIAL

We explored three different materials for the construction of the cooling box and

frame of the device. These were aluminum, wood and thermacol. High impact

polystyrene is desirable as it has a low thermal conductivity. Building the device

out of would make it very light, portable while maintaining rigidity is readily

available and reasonably priced, is easy to cut and drill. The outer casing and

container would be made by first making a positive mold and applying a cloth

coated with resin.

Fig.3.5 Schematic description of an experimental thermoelectric refrigeration

system.

Chapter 4

19

ANALYSIS

4.1 EXPERIMENTAL SETUP

The experimental setup of the given project is shown below. It is a protype of

thermoelectric refrigeration system.

Fig.4.1.Internal View of Prototype TERS

20

Fig.4.2. Back View of Prototype TERS

21

Fig.4.3. Side View with digital thermometer attached of Prototype TERS

4.2 EXPERIMENTAL ANALYSIS

Experimental analysis was done in three stages. This helps to know about the

detailed information about the instruments, working procedure and operating

parameters of the thermoelectric cooling system. They are as follows:

1) COP :

It is seen that the COP is a function of the material dimension property of

thermocouple, the temperature of the hot side and cold side Th, Tc and the

current input. There exists an optimum current for maximum COP, if Th, Tc,

and thermoelectric material are fixed.

So analysis of COP is done by varying the various parameters such as input

current, voltage and temperature difference and their effect on COP is study

for fix geometric parameters.

22

a) Influence of Current (I) on COP:

The expression for the coefficient of performance is defined in equation

(6).Fig. 4 is a simulation of coefficient of performance against input current at

20°C temperature differences.

0 2 4 6 8 10 12

-1

-0.5

0

0.5

1

1.5

COP vs I

Fig.4.4. COP vs. Current Graph

Where,

x-axis = current (I)

y-axis = COP

It can be seen that from the plot that the C. O. P. increases with an increase in

input current, gets to a peak value and then begins to decrease at various

temperature differences. The unique feature of the graph is with the DT = 20,

the smallest temperature differences, it shows that the C. O. P is maximum

with the smaller temperature difference between the source and sink.

Therefore, for optimum performance of the thermoelectric cooler, the

temperature difference between the source and sink should be kept as low as

possible. C. O. P is a measure of modules efficiency and it is always desirable

to maximize C. O. P.

23

2) Time vs temperature :

The experimental result (Fig.4.) shows that at input electrical current condition

0.5Imaxi and at forced air convection condition the temperature reduction at

cold side of module with respect to ambient at 30oC was maximum.

With these optimized operating condition (I=0.5Imaxi and at forced air

convection) experiments were conducted for performance evaluation of

developed experimental thermoelectric refrigeration cabinet without any heat

load inside cabinet and results shown in fig. below.

0 10 20 30 40 50 60 70 800

5

10

15

20

25

30

time vs temp.

Fig.4.5.Time vs. Temp. Graph without load

Where,

x-axis = time in min.

y-axix = temperature in °C

3) Cooling temperature of Fruit (Orange):

The orange directly on surface of cooling chamber and measuring temperature

by thermocouple for analyzing the cooling effect on fruit(orange) and reading

is taken by inserting thermocouple rod in orange and then take reading after

one minute time interval and measure temperature reading.

24

0 10 20 30 40 50 60 70 800

5

10

15

20

25

30

time vs temp.

Fig.4.6. Time vs. Temp. Graph with load

In analysis of orange fruit, the graphical representation figure 3 shows

initially fruit cooled fastly. The temperature decreases from 28°C to

22°C.within 20 minutes and then taken 80 minutes to decrease another

4◦C. The cooling rate for Orange is (28-22)/20=0.3

4.3 COST ANALYSISThe cost analysis of the project is given below:

S. No. Items Cost (in Rs.)

1 Thermoelectric module 50002 Wood 2003 Aluminium foil 5004 Thermocol 100

5 Transformer 5006 Capacitor 1007 Switch 1508 Digital Temp. Control

Device1200

9 Extra 750

25

Chapter 5

RESULT

5.1 RESULT AND DISCUSSIONTo verify the above system design analysis, we have designed and built a

prototype thermoelectric refrigeration system and perform an experiment. The

picture built of the thermoelectric refrigeration system is shown in figure 4.1 to

4.3. The thermoelectric module is used for the experiment.

Cooling Rate Test Data:The test was conducted at 25-30°C represented in figure 4.4-4.6. The temperature

vary from 25°C to 6°C with temperature variation within the TEC is less than 1°C

as this was the prototyping we can achieve even lower temperature.

26

27

28

Fig.5.1. Readings

TEC Retention:The retention time is calculated as per test procedure. As the current carrying

capacity of Peltier cell is high as 9 Amp the battery to be used will be 12 V.

Therefore different method has to be employed to achieve the desired temperature.

All this method was mentioned above.

5.2 CONCLUSION

The research effort made by different researchers for design and development of

novel thermoelectric refrigeration and space conditioning systems has been

thoroughly reviewed in this paper. Also the advantages and cost-effectiveness

offered by thermoelectric cooling system over conventional cooling system have

been explained. A temperature reduction of 11°C without any heat load at 30°C

ambient temperature in first 20 minutes has been experimentally found at

optimized operating conditions. The calculated COP of developed experimental

thermoelectric refrigeration cabinet was 0.1. The available literature shows that

thermoelectric cooling systems are generally only around 5–15% as efficient

compared to 40–60% achieved by conventional compression cooling system. This

is basically limited by figure of merit of thermoelectric material and efficiency of

heat exchange system. Continuous efforts are given by researchers for

development of higher figure of merit thermoelectric materials may provide a

potential commercial use of thermoelectric refrigeration and space conditioning

system. Also compatibility of thermoelectric cooling systems with solar energy

made them more useful and appropriate for environment protection.

29

5.3 FUTURE SCOPE

With recent development taking place in field of thermoelectric and nano science

different thermoelectric material with figure of merit ZT more than 1 with high

temperature difference to be explored this will further help to reduce the

temperature, current below and can also perform better at higher ambient

conditions. To improve the power retention in this thermoelectric cooler sandwich

heater needs to be explored with quick switching mechanism from thermoelectric

cell off state of heater to on state, so that temperature drop in thermoelectric cell

can be reduced.

5.4 REFERENCES1. Rowe D. M., 1995, CRC handbook of Thermoelectrics

2. Huang B.J., Chin C.J. & Duang C.L., 2000, “A design method of

thermoelectric cooler”, International Journal of Refrigeration, 23: 208-218.

3. Rowe D. M., 2006, Thermoelectrics handbook: Macro to Nano, CRC,

Taylor & Francis

4. Xi Hongxia, Luo Lingai and Fraisse Gilles, 2007, “Development and

applications of solar-based thermoelectric technologies”, Renewable and

Sustainable Energy Reviews, 11(5): 923-936.

5. Dai Y. J., Wang R. Z. and L. Ni, 2003, “Experimental investigation and

analysis on a thermoelectric refrigerator driven by solar cells”, Solar

energy material and solar cells 77:377-391.

6. Gao Min and Rowe D.M., 2006, “Experimental evaluation of prototype

thermoelectric domestic-refrigerators”, Applied Energy, 83 (2): 133-152.

7. Sabah A. Abdul-Wahab, Ali Elkamel, Ali M. Al-Damkhi, Is'haq A. Al-

Habsi, Hilal S. Al-Rubai'ey', Abdulaziz K. Al-Battashi, Ali R. Al-Tamimi,

Khamis H. Al-Mamari and Muhammad U. Chutani, 2009, “Design and

experimental investigation of portable solar thermoelectric refrigerator”,

Renewable Energy, 34 (1): 30-34.

8. Abdullah M. O., J. L. Ngui, K. Abd. Hamid, S. L. Leo, and S. H. Tie,

2009, “Cooling Performance of a Combined Solar Thermoelectric-

Adsorption Cooling System: An Experimental Study”, Energy Fuels, 23:

5677–5683.

30

9. Putra N., 2009, “Design, manufacturing and testing of a portable vaccine

carrier box employing thermoelectric module and heat pipe”, Journal of

Medical Engineering & Technology, 33 (3): 232-237.

10. Adeyanju A.A., E. Ekwue and W. Compton, 2010, “Experimental and

Theoretical Analysis of a Beverage Chiller”, Research Journal of Applied

Science, 5 (3): 195-203.

11. Lertsatitthanakorn C., Lamul Wiset, and S. Atthajariyakul, 2009,

“Evaluation of the Thermal Comfort of a Thermoelectric Ceiling Cooling

Panel (TE-CCP”), System Journal of Electronic Materials, 38: (7) 1472-

1477

12. Gillott Mark, Liben Jiang and Saffa Riffat, 2010, “An investigation of

thermoelectric cooling devices for small-scale space conditioning

applications in buildings”, International Journal of Energy Research, 34:

776–786.

13. Bansal P. K. and Martin A., 2000, “Comparative study of vapour

compression, thermoelectric and absorption refrigerators”, International

Journal of Energy Research, 24: 93-107.

5.5 INDEX

The tables for different data are given below:

1. COP vs. Current (I) at 20°C temperature difference.

S. No. I (in Ampere) C.O.P

1 1 -0.6743

2 2 1.3336

3 3 1.3135

4 4 1.1153

5 5 0.9250

6 6 0.7651

31

7 7 0.6337

8 8 0.5252

9 9 0.4348

10 10 0.3585

11 11 0.2934

2. Time vs. Temperature without any load.

S. No. Time (in minute) Temperature in °C

1 0 28

2 5 25

3 10 22

4 20 19

5 25 17

6 30 15

7 35 13

8 40 11

9 45 10

10 50 9

11 55 8

12 60 8

13 65 7

14 70 7

32

15 75 6

16 80 6

3. Time vs. Temperature with load.

S. NO. Time (in minute) Temperature in °C

1 0 28

2 5 27

3 10 26

4 15 25

5 20 24

6 25 23

7 30 22

8 35 22

9 40 22

10 45 21

11 50 21

12 55 21

13 60 21

14 65 20

15 70 20

16 75 20