The Thermal Performance Of Peltier Cooling Engineering Essay

This paper is intended to investigate the thermal performance of peltier cooling by applying the basic thermoelectric theory. One of the methods in achieving the best cooling capacity of peltier module is to remove the temperature of the hot side of the peltier plate in a very effective way so that the temperature difference between the hot side and the cold side can shift or concentrated on the cool side.

A whole series of experiments are conducted to compare the performance of different type of heat sink. One of the difficulty in this type experiments is the mounting of heat sink and the measurement of temperature. A successful measurement should consider the material of the peltier module, heat sink compound, material of heat sink as well as the mounting method to achieve the best binding force.

It was found that when different types of heat sink methods are applied to dissipate the heat from the hot side of the peltier module, the cold side temperature is proportional to the rate of temperature drop, the pressure applied to the peltier module as well as the thermal conductivity of the heat sink. Metallic heat sink of various form and shape together with water cooled heat sink are used and it was found that water-cooled heat sink has the best performance which can achieve -22 degree Celsius at ambient condition. A new type of heat sink arrangement is proposed which believes when used can achieve a higher cooling capacity.

Contents

Chapter Page

Introduction

-Background

– Problem statement

– Aims and objectives

– Limitation of the study

– Structure of the report

– Formulation of the project topic

– Justification of the project

Literature review

-Thermoelectric principle

– Heat sink research

Methodology

– Procedure for setup Peltier Module

– Various metallic conductors on Peltier Module

– Compression Pressure on Peltier Module

– Water cooling for metallic conductor on Peltier Module

Result and Discussion

– Experience Results for testing no. 1

– Experience Results for testing no. 2

– Experience Results for testing no. 3

– Experience Results for testing no. 4

Conclusions and Future Application

– Conclusions about the project

– Future Application

Reference

Appendix

Photo record for experience result (Various metallic conductors on Peltier Module)

Photo record for experience result (Compression Pressure on Peltier Module)

Photo record for experience result (Compression Pressure on Peltier Module)

Photo record for experience result (Water cooling for metallic conductor on Peltier Module)

Acknowledgements

The author would like to give sincerely thank to my supervisor, Dr. Joseph Wong who gave me advice and guidelines and my classmates, Mr. Steven Ko Kin Him who taught me how to consolidate the study of my research. The author also appreciate the assistance the technicians of BSE Laboratory, especially Mr. Yue.

Chapter 1 – Introduction

Background

Conventional refrigeration has two ways. One of the Absorption refrigerators, it is used the compression and expansion of gas for mechanical pump through a thermodynamic cycle. The advantage are noiseless being operation and useful in any heat likely electricity applications. And the disadvantages a low coefficient of performance as the product combine heat engine and pump (fixed performance in device).

Another one of the Mechanical refrigerant that have a highly coefficient of performance, moreover, it have the long operating life time without maintenance. However it produce the noise and the cooling power is large without reduce. The mechanical operation only between on and off as well as the fuel gas effect have harmful for environment.

The thermoelectric cooling (Peltier cooling), are generally much less performance than the mechanical refrigerant. The other way round they not only can maintain the low cooling power but the operating are silent and have neither motion parts nor gases to leak. Because of that they are solid-state devices therefore have a long life time depends on the design and fabrication. So it will very popular in Hong Kong.

Problem statement

One of the low cooling capacity of the existing peltier application: peltier refrigerator. It is the small size of the refrigerator. The advantages are less sound against the every 15 minutes motor turn on. it also a protable device which located at the car and plugging into car’s cigarette lighter instead of power supply. On the other hand, the disadvantage of the peltier effect refrigerator is that it’s not very powerful, nor is it very efficient.

Aims and objectives

The aims of this project is design and fabricate are hardware devices to produce the peltier cooling of thermoelectric and collect the data at the same time. The cooling gradient is related between the compression pressure, voltage, ampere, temperature, the material and the form of the various metallic conductors.

The following objectives were proposal in this study:

Based on the principle of peltier effect, supply DC voltage and to absorb the thermal energy based on the thermoelectricity.

To develop new hardware setup to maximize the cooling effect from absorb the thermal energy by the peltier effect.

To study the effect of various heat sink for cooling on thermoelectric device in terms of peltier cooling.

To study the effect of water cooling on thermoelectric device in terms of peltier cooling.

To study the effect of pressure on thermoelectric device in terms of peltier cooling.

To measure and comparison the rate of change effect from the thermoelectric device based on various metallic conductor and compression pressure for release heat.

To confirm the peltier effect theory against the experience setup.

Limitation of the study

Structure of the report

Formulation of the project topic

We are deciding that the topic of the project is “Renewable Energy – Cooling effect by the Peltier”.

Justification of the project

Refrigeration technology is highly to use in different device for human comfortable, science application. In spite of this cooling application are expensive and do not easy for use / fabricate, example, air conditioner, refrigerator, cooling device are produce one device and the size is not much small. Another disadvantage is not work on tilted or unsuitable for many marine application. In the Peltier Effect, the plate can produce the cooling side for the application.

Chapter 2 – Literature review

Thermoelectric principle

Heat sink research

Chapter 3 – Methodlogy

Procedure for setup Peltier Module

Based on the theory for the conversion efficiency of a thermoelectric device, the ideal thermocouple shown in Figure 1.

Figure 1

The thermocouple consist of a positive (p) and negative (n) branch to which are attached heat sink. Assume that the heat is transfer from the heat source at upper side to the heat sink at lower side through by conduction along the thermocouple. The thermocouple can be used as heat pump or refrigerant. We are discussed the refrigerant. The heat is pumped out from the source at upper side to the heat sink at lower side by means is peltier effect1. So the setup is supply the specific DC voltage output and then the heat energy is absorbed to the heat sink under the peltier of the thermoelectric theory. Besides, use the electric thermometer to measure the temperature of cold side as Figure 2.

Figure 2

Various metallic conductors on Peltier Module

In this section, the various metallic conductors would be used to test the best of the heat release, the theory is increase the cooling capacity by means the heat energy is absorbed and transfer to the metallic conductor thriugh the thermoelectric device. There are the various material, various size and the shape. This experience is discovered the best material is made the best of negative degree Celsius and keep it about two minutes. The Heatsink Thermal Resistance calculation as the following terms2:

Tr – Temperature rise

Ta – Ambient temperature

Th – Heatsink temperature

Vh – Voltage to heater

Ih – Current to heater

Ph – Power applied to heatsink

Rth – Thermal resistance (in °C/W)  

so …

Tr = Th – Ta

Ph = Vh * Ih

Rth = Tr / Ph

Compression Pressure on Peltier Module

This section is going to enlarge the conductive between peltier and heat sink and then increase the heat transfer to the heat sink through the thermoelectric device. There are used three different weight add on from top of the cold side to the thermoelectric device and the heat sink. In additional, there are used the force air convection by using a fan to aid the cooling process or otherwise the temperature of a thermoelectric device rises above the its maximum allowable temperature, there is a need to dissipate this temperature or else the device will breakdown as Figure 3.

The setup of the hardware have consists the aluminum loading, copper metal, heat sink for release the heat and the fan for increase the force air convection and keep the experience can provide 30 seconds.

Compression Pressure

Figure 3

Water cooling for metallic conductor on Peltier Module

When a junction temperature of a thermoelectric device rises. Although the force air convection done by fan could save the device will not break down. But this method can not help the thermoelectric operating in one hundred percentage. Therefore, the water cooling with low temperature (about 7 degree Celsius) for metallic conductor. The Liquid is far denser than air, meaning that in a given space, many more liquid molecules are available to convect heat : Water-cooled heat sink as Figure 4.

Figure 4

Chapter 4 – Result and Discuss

Experience Result for testing no.1

4.1.1 Introduction:

The cooling performance curves are made by the three major types material such as, Aluminum metal, Copper metal and iron material and there have total eight numbers of metal basic form of the heat sink. The experiment produced the temperature gradient of the cooling side of thermoelectric device and relationship between the temperature, voltage, ampere and various conductive materials.

In this experiment the following apparatus was used.

Peltier DC power supply

Various metal size and Mass as below:

Material No.

Material

Mass of Heat Sink (g)

Size (LxWxH)

1

Copper

1716

200x100x10

2

Copper

1838.79

100x45x45

3

Copper

2232.82

260x100x10

4

Aluminum

616.7

160x40x40

5

Aluminum

2617.78

150x125x135

6

Aluminum

514.16

120x120x35

7

Copper

1961.61

120x120x35

8

Iron

3009.35

150x50x50

The cooling performance result and curve as below:

Material No.

Material

Time (S), Voltage (V)

20, 2

40, 4

60, 6

80, 8

100,10

120,12

1

Copper

Temp (°C) on Pilter Plate

9.9

-0.6

-9.2

-14.9

-18.4

-20.3

　

　

Temp (°C) on Heat Sink Plate

23

23.1

23.4

23.8

24.5

25.6

2

Copper

Temp (°C) on Pilter Plate

9.3

-1.1

-10.9

-17.1

-20.5

-21.1

　

　

Temp (°C) on Heat Sink Plate

22.3

22.5

22.7

23.4

24.2

25.5

3

Copper

Temp (°C) on Pilter Plate

9.6

-0.9

-9.3

-15.8

-20.8

-22.2

　

　

Temp (°C) on Heat Sink Plate

22.3

22.5

22.8

23.3

24.1

25.1

4

Aluminum

Temp (°C) on Pilter Plate

10

-0.2

-8.7

-14.1

-18.3

-19.2

　

　

Temp (°C) on Heat Sink Plate

22.6

22.7

23.1

23.8

24.9

26.4

5

Aluminum

Temp (°C) on Pilter Plate

8.8

-1.8

-10.7

-16.4

-19.8

-19.9

　

　

Temp (°C) on Heat Sink Plate

22.1

22.1

22.1

22.3

22.8

23.6

6

Aluminum

Temp (°C) on Pilter Plate

8.9

-1.9

-10.5

-15.7

-18.5

-17.5

　

　

Temp (°C) on Heat Sink Plate

21.9

22.2

22.6

23.3

24.1

25.6

7

Copper

Temp (°C) on Pilter Plate

8.9

-1.7

-10.2

-16.4

-17.9

-19.9

　

　

Temp (°C) on Heat Sink Plate

22.4

22.7

22.7

22.9

24.3

24.4

8

Iron

Temp (°C) on Pilter Plate

9

-1.8

-10.2

-16

-19.4

-19.8

　

　

Temp (°C) on Heat Sink Plate

21.8

21.8

21.9

22.1

22.3

22.7

4.1.2 Compare the performance of different types of heat conductive between copper, Aluminum and iron

Being the cooling performance curve graphic, the relationship of the voltage, temperature and specific time were shown at no compression pressure on the peltier and heat sink.

Compare with the performance of different types of metal temperature (°C) against specific time (s) and voltage (V), it is showed that the copper types metal was increasing after two minutes and the cooling side of the peltier was decreasing at negative 25 degree Celsius after reaching 2 minutes.

Refer to the calculation of Measuring Heat sink Thermal Resistance as below

The Heat sink Thermal Resistance calculation as the following terms2:

Tr – Temperature rise

Ta – Ambient temperature

Th – Heatsink temperature

Vh – Voltage to heater

Ih – Current to heater

Ph – Power applied to heatsink

Rth – Thermal resistance (in °C/W)  

so …

Tr = Th – Ta = 54 – 22 = 32°C

Ph = Vh * Ih = 12 * 3.5 = 42W

Rth = Tr / Ph = 32 / 42 = 0.76°C/W

Ambient Temperature 19.5 (°C), Voltage 12(V)

Material No.

Material

Mass of Heat Sink (g)

Size (LxWxH)

Th

Ta

Ih

Vh

Tr

Ph

Rth (°C/W)

1

Copper

1716

200x100x10

25.6

19.5

5

12

6.1

60

0.101666667

2

Copper

1838.79

100x45x45

25.5

19.5

4.4

12

6.0

53

0.113636364

3

Copper

2232.82

260x100x10

25.1

19.5

5.3

12

5.6

64

0.088050314

4

Aluminum

616.7

160x40x40

26.4

19.5

4.5

12

6.9

54

0.127777778

5

Aluminum

2617.78

150x125x135

23.6

19.5

5

12

4.1

60

0.068333333

6

Aluminum

514.16

120x120x35

25.6

19.5

5.3

12

6.1

64

0.09591195

7

Copper

1961.61

120x120x35

24.4

19.5

4.6

12

4.9

55

0.088768116

8

Iron

3009.35

150x50x50

25.3

19.5

4.6

12

3.2

55

0.105072464

The best of the Heat sink Thermal Resistance is material no. 3

4.1.3 Discussion

Refer to the cooling performance curve, the best of the material types is the copper metal, it can provide the high cooling capacity by means the heat energy is absorbed that is transfer to the thermoelectric device. Moreover, the mass of the heat sink and shape is effected by the result. The best of the copper metal – material no.3 have the largest size and the heaviest of the same type.

Besides, the above calculation are shown the best of the heat sink thermal resistance is copper metal – material no.3.

Experience Result for testing no.2

4.2.1 Introduction:

The cooling performance curves are made by the additional weight on the peltier and heat sink. The compression pressure is going to enlarge the conductive between peltier and heat sink and then increase the heat transfer to the heat sink through the thermoelectric device. There are using the three different weight, such as, 2576.97g, 3315.55 and 4802.48 of the aluminum metal. Besides, there are used the force air convection by using a fan to aid the cooling process or otherwise the temperature of a thermoelectric device rises above the maximum allowable temperature. The experience is used 360 seconds to got a result. The experiment produced the temperature gradient of the cooling side of thermoelectric device and relationship between the temperature, voltage, ampere and various compression pressure.

In this experiment the following apparatus was used.

Various mass of the compression pressure as below:

Material No.

Material

Mass of Heat Sink (g)

Size (LxWxH)

Total Weight on the Pilter (g)

　

1

Copper

1838.79

100x45x45

2576.97

g

　

　

　

　

3315.55

g

　

　

　

　

4802.48

g

The cooling performance result and curve as below:

Total Weight on the Pilter (g)

　

Time (S)

30

60

90

120

150

180

210

240

270

300

330

360

2576.97

g

Temp (°C) on Pilter Plate

17.7

17.1

16.3

15.6

14.9

14.2

13.6

13

12.5

12

11.6

11.1

3315.55

g

Temp (°C) on Pilter Plate

18.6

17.7

16.8

16

15.3

14.6

13.8

13.4

12.7

12.3

11.8

11.1

4802.48

g

Temp (°C) on Pilter Plate

18.8

17.5

16.6

15.8

15

14.4

13.7

13.1

12.5

11.9

11.4

11

4.2.2 Compare the performance of different mass for compression pressure on the peltier

Being the cooling performance curve graphic, the relationship of the voltage, temperature and specific time were shown at compression pressure on the peltier and heat sink.

Compare with the performance of different types of metal temperature (°C) against specific time (s) and specific mass (g), it is showed that the heaviest of mass was increasing the compression pressure at the ends and the cooling side of the peltier was decreasing at 11 degree Celsius after reaching 6 minutes.

4.2.3 Discussion

In this experience, although some of the experimental result was not exactly complied with the theoretical result on the beginning, some implications were given from this laboratory experiment.

The heaviest of the mass for the compression pressure was not the lowest degree Celsius on the beginning and then on the contrary the result comply with the theoretical result.

Experience Result for testing no.3

This experience is shown out the cooling performance by the forced liquid convection. And the performance curve as below.

ALL experiment took at 30 seconds

Ambinet Temperature (°C): 21.5°C

Base Heat Sink Material: Aluminum

Mode1

No Installed insulation on Heat sink

Material No.

Material

Time (S)

Voltage (V)

Ampere (A)

Water Temp. (°C)

Heat sink Temp. (°C), Pilter Off

Heat sink Temp. (°C), Pilter On

Pilter Temp (°C), Pilter Off

Pilter Temp (°C), Pilter On

　

Aluminum

30

6

3

4.5

　

9.4

　

-19.2

　

　

30

10

5.2

4.5

　

10

　

-27.3

　

　

30

12

6

4.5

　

10.4

　

-28

Mode 2

Installed insulation on Heat sink

Material No.

Material

Time (S)

Voltage (V)

Ampere (A)

Water Temp. (°C)

Heat sink Temp. (°C), Pilter Off

Heat sink Temp. (°C), Pilter On

Pilter Temp (°C), Pilter Off

Pilter Temp (°C), Pilter On

　

Aluminum

30

6

3.1

7

7

7.2

7.5

-25.5

　

　

60

6

3.2

7.9

7.9

8.4

8.7

-23.6

　

　

60

5

2.6

7.9

7.9

8.2

8.5

-21

Discussion:

Refer to the Graphic A, The Temperature of Mode B is lower than the Mode A Pilter at 6 Voltage.

2. Refer to the Graphic B, The Timing affected the Result of Pilter

4.4 Experience Result for testing no.4

4.4.1 Compare the performance of peltier cooling between the copper metallic , compression pressure mode and liquid convection mode on the peltier

The technical data as below:

ALL experiment tested within 20 mins.

Ambinet Temperature (°C): 21.2°C

Voltage (V): 6V, Constant

　

Material

Mass of Heat Sink (g)

Size (LxWxH)

Total Weight on the Peltier (g)

　

Time (S)

30

60

90

120

150

180

210

240

270

300

330

360

Mode1

Copper

2232.82

120x120x35

1838.79

g

Temp (°C) on Pilter Plate

19.4

18.4

17.4

16.6

15.8

15

14.2

13.2

12.9

12.3

11.7

11

Mode2

Copper

2232.82

120x120x35

8796.96

g

Temp (°C) on Pilter Plate

18.4

17.4

16.4

15.6

14.8

14

13.3

12.6

11.9

11.3

10.7

10.1

Mode3

Aluminum

1116.67

146x146x30

1838.79

g

Temp (°C) on Pilter Plate

17.2

16.1

15.1

14.1

13.2

12.2

11.4

10.6

9.8

9

8.3

7.7

　

Material

Mass of Heat Sink (g)

Size (LxWxH)

Total Weight on the Peltier (g)

　

Time (S)

390

420

450

480

510

540

570

600

15min

20min

Mode1

Copper

2232.82

120x120x35

1838.79

g

Temp (°C) on Pilter Plate

10.5

10.1

9.6

8.8

8.6

8.4

8

7.7

4.9

3.4

Mode2

Copper

2232.82

120x120x35

8796.96

g

Temp (°C) on Pilter Plate

9.6

9.2

8.7

8.3

7.9

7.5

6.9

6.7

4.2

2.7

Mode3

Aluminum

1116.67

146x146x30

1838.79

g

Temp (°C) on Pilter Plate

7.1

6.4

5.8

5.3

4.8

4.1

3.8

3.4

-0.2

-2.4

The experience would like to introduce the cooling effect in the Mode 1, Mode 2, Mode 3. The temperature testing point at the lower level of the copper column (refer to the photo) and then use of the thermometer tube to collect the temperature different in conjunction with the time.

Temperature Measuring point

Temperature Measuring point

The performance curves as below:

The above figure was prove that the force liquid convection (mode 3) is the best of the heat release method. The cooling capacity is increase by means the heat is absorbed that is transfer to the thermoelectric device continuously.

Chapter 5 – Conclusion

Refer to the experience 1, it showed that the copper is the best material for the heat sink in the specific time and voltage. Furthermore, the heat sink gave fins which can increase the air by the convection.

Another experience 2, provide a pressure which from the top to the heat sink and peltier to gave a good conductive (contact) between the heat sink and peltier. It showed out the pressure was the important factor in the thermoelectric cooling (peltier effect).

In the experience 3, heat transfer by the cooling water on the heat sink to brought the heat to sink is the best of the experience 2. Moreover, it accepted two degree water different when the peltier in operating mode.

From the research data for the thermoelectric cooling, the heat transfer by cooling water is the best method. But the installation of the accessories do not convenience such as the water pipework and the circulating pump which are never silent and the maintenance concern.

In the experience, it showed out the heat transfer by water for heat sink which was the best of the produce the low temperature of peltier.

In the above mentioned, increase pressure would be choose for the environment and energy saving for the installation cost.