Power Supply Emergency

As we are used to multiple machines that need to be powered all the time, the world we live in today is mainly powered by electricity. However, there are some parts of the world, especially in rural and other remote areas, where unexpected power outages often impede access to power. The issue of the low power supply is faced in other parts of the globe, apart from this region. Thus, I invented a thermos in 2016 that can transform thermal energy into electric energy to help solve this problem. The electric energy it produces can be sufficient to charge phones in case the mains supply is out of service/ or in other emergency cases. Already power supply devices have been created, but what happens where people cannot even access electricity yet they have a thermos that not only keeps their fluids hot but also helps charge their phones? The whole idea is about ‘going Green.’

The research question for this paper is, “How does the ambient temperature influence the electric energy production of the Thermoelectric Generator (TEG)?” An answer to this question will be explaining how my invention works while evaluating its commercial viability. In the end, this paper provides proof beyond doubt that this invention should find its way to the factory. The following variable will help explain the functioning of the device.

Ambient Heat/ Temperature (AMB)

Ambient heat is heat produced by heating or cooling mediums into the environment surrounding them. On the other hand, ambient temperature is a derivative of the ambient heat, being a measure of the ambient heat. Ambient heat/ temperature is an independent variable that is measured in degrees Celsius. Room temperature is taken to be 23˚C.

Time

Time is the measure of the successive events that take place from the moment the experiment begins to the end which defines the bind of the trials. Time is measured in seconds (s). It is one of the independent variables in the experiment.

Voltage Output (V)

Voltage output is the electromotive force that moves within the circuit representing the potential difference between the effort and the load in classical mechanics. Voltage is measured in volts (V), and it is one of the dependent variables in the experiment.

Power (W)

Power is the rate of doing work- otherwise known as the rate of energy consumption per unit time. It is a derived quantity and is used as one of the dependent variables. Power is measured in watts (W).

Average Power

Average power is a derivative of all the trials in the experiment to obtain the most accurate results. It is a dependent variable.

Current (I)

Current (I) is the quantity of electric charge per unit time. It is a dependent variable and will be measured in Amperes.

Controlling the Variables

The Independent Variables

In this experiment there are two independent variables: Time and temperature. Time is set to start from 0s to 4594s. On the other hand, temperature is manipulated by raising it to 90 degrees then let to reduce through ambient cooling. Temperature difference, which is the derivative of the thermos internal temperature (T) and room temperature (TR) of 23˚C, is found by subtracting TR from T. From all the trials, 33˚C is the minimum temperature difference that produces power. Data are recorded on an excel spreadsheet and graphs drawn using the same software.

Dependent Variables

Power, Voltage and Current are the dependent variables. Power is measured using an electronic wattmeter for precision since the power being measured is small. Also, a digital voltmeter is used to measure the potential difference with precision. Lastly, an ampermeter is used to measure the current and also confirm the readings for voltage and power. Power P is found by saying P= IV. Meaning that I= P/V. Data are recorded on an excel spreadsheet and graphs drawn using the same software.

Data Collection Method

Materials and Equipment

Bunsen burner, beaker, funnel, thermometer, stop watch, TEG, Digital Voltmeter, electronic wattmeter, and ampermeter.

Procedure

Water is boiled in a 1liter beaker on a Bunsen burner to a temperature of 92 degrees.

The water is then transferred into the TEG by pouring into the vacuum structure using a funnel

The temperature is measured once again by dipping a thermometer letting it cool until in reads 90 degrees.

It is then closed, and temperature measured in intervals of approximately 120 seconds.

Temperature measurement is continued for utmost 4594 seconds (Approx. 76.57 seconds).

Room temperature is assumed to be 23˚C

Ambient temperature is the difference between the temperature of water in the flask and the room temperature expressed as (T-TR).

A phone charging port is established, a circuit created with a DVM, ampermeter connected

Power is calculated by saying where I is current measured by the ampermeter

This process is repeated three times to get data that will be averaged for accuracy.

Results

The results of the experiments are shown in the appendix. Table 1 has all the data averaged with all the variables present. The rest of the data is attached as the appendix.

Table 1: Average results

t/s

T (˚C)

T-TR(˚C)

VA

IA

WA

Power 2

0

90

67

3.161

0.611

1.931

1.931

120

88

65

2.831

0.584

1.654

1.654

240

86

63

2.764

0.542

1.499

1.499

371

84

61

2.543

0.520

1.322

1.322

503

82

59

2.394

0.488

1.169

1.169

640

80

57

2.143

0.470

1.008

1.008

782

78

55

2.071

0.445

0.920

0.920

928

76

53

2.002

0.408

0.816

0.816

1081

74

51

1.919

0.385

0.739

0.739

1239

72

49

1.759

0.351

0.618

0.618

1404

70

47

1.572

0.340

0.534

0.534

1576

68

45

1.467

0.309

0.453

0.453

1756

66

43

1.293

0.293

0.379

0.379

1945

64

41

1.171

0.260

0.304

0.304

2143

62

39

1.025

0.230

0.236

0.236

2351

60

37

0.787

0.198

0.156

0.156

2571

58

35

0.558

0.185

0.103

0.103

2804

56

33

0.314

0.164

0.052

0.052

3052

54

31

0.001

0.143

0.000

0.000

3316

52

29

0.001

0.030

0.000

0.000

3599

50

27

0.001

0.002

0.000

0.000

3904

48

25

0.001

0.002

0.000

0.000

4234

46

23

0.001

0.002

0.000

0.000

4594

44

21

0.001

0.002

0.000

0.000

t is time in seconds; VA is average voltage; IA is average current; WA is average power

Analysis of the Results

Initially, the temperature of the water in the thermos is hot, at 90 degrees Celsius. However, with the ambient currents passing, the water loses heat through time. Thus, as time increases, the temperature reduces. The total average time used to conduct the experiment is 4594 seconds which is equivalent to 76.57 minutes. In appendix A temperature versus voltage output is tabulated. The table explains thermoelectric generation without moderation or amplification. It shows that as temperature reduces voltage also falls up to when the temperature is 56 degrees Celsius. Below 56 degrees a negligible voltage is recorded. In appendices B, C, D, and E temperature difference is recorded against voltage, current, power and current at 5V. In all the four trials, negligible voltage is produced when the temperature difference falls below 33 degrees centigrade. This implies that the threshold for producing power is 33˚C. In addition, effective power is produced when the temperature difference is 47˚C.

Time and Power

Diagram 1 is a graph that was plotted to include time values from t=0s to t= 2804s. Time is bound between 0 and 2804 seconds since that is the time interval within which the temperature difference can produce electric energy. The slope of the graph is negative since it depicts an inverse relationship between time and reduction of heat that is required to generate the electric energy. Average power is shown by two line graphs. The blue line is for average power while the red line indicated exponential average power.

Diagram 1: Power versus Time

According to the first law of thermodynamics, power can only be produced if there is a difference in the heat produced. Thus, if ambient heat is the only source then there will be no differential hence no power (Jawad, Abdul, et al 8). The second law, which is a corollary of the first, also implies that only a temperature is not sufficient to cause the generation of power (Jawad, Abdul, et al 10). Thus, in any situation, the difference in temperature leads to an energy flow from the source of heat to the surrounding. The heat source leads to heating while the environment to which the heat is moving towards causes cooling. According to Newton’s law of cooling, “the rate of change of the temperature of an object is proportional to the difference between its own temperature and the ambient temperature” (O’Sullivan, Colm 956-7). Thus, the higher the temperature difference the higher the power produced.

This relationship brings into focus the equation of exponential decay which is applicable to the current situation where the temperature difference is reducing with respect to time.

In the equation above, the area under the curve represents the energy produced by the TEG. At t=0, the power produced is 2.2.38W, and it reduces as time increases from 0s to 4594s. The conclusion in this case is that ambient temperature affects the production of electricity if and only if there is a temperature difference. If the temperature of the system is equivalent to the ambient temperature, then the temperature of the whole set up can be called ambient temperature whose differential is zero.

Current versus Time

Diagram 2: Average Current versus Time

As time increases, the average current reduces. This happens since as time advances the temperature difference that is supposed to generate the thermoelectric energy falls. The area under the graph of current against time gives charge. Thus,, and ; which implies that charge increases with an increase in voltage and reduction on resistance.

Data Comparison

The data comparison chart combines the average voltage, average current and average power data. Voltage, which is the quotient of power P and current I increase with a reduction in current. The opposite is true. Temperature difference between the system and room temperature causes a flow of energy which is responsible for power generation. Therefore, a higher ambient temperature results in more power production. Exponential decay of the power function explains why the cooling process as explained in Newton’s law is quintessential. A higher temperature difference is desired for TEG power generation without which we say that the ambient temperature does not allow for heat transfer.

Diagram 3: Data comparison graph

Discussion

The Design of the TEG

The thermoelectric generator is design in a way that it has five main components: the inner vacuum structure, outré protection rim, the TEG, heat transfer connection point and the radiator. Water is poured in the inner vacuum of the thermos and held there to the entire duration of the experiment. The TEG is responsible for converting thermal energy into electricity depending on the amount of heat. The heat transfer connection point is responsible for passing on excess heat to the radiator. The radiator allows ambient currents to cool the generator from below.

Diagram 4: the Thermoelectric Generator

Thermal Physics and Newtonian Mechanics

Thermal physics concerns with heat, temperature and heat transfer in the different states of matter. In a nutshell, it deals with thermal energy which is one of the most useful forms of energy on the planet earth. Thermal physics becomes so relevant when the second law of thermodynamics is considered and its wide array of applications explored. In almost every physical process thermal energy is produced (Ben-Naim, Arieh 9,216). For instance, two surfaces rubbing against each other produce heat due to friction. Newtonian mechanics explains this phenomenon in mathematical sense giving efficacy to thermodynamic physics.

Newton’s first law of motion, which is also referred to as the law of inertia categorically determines that motion and rest are static unless an external force comes into perspective (Warren, N. G 128). In this case, any stationary body contains potential energy, and a moving object contains kinetic energy. Thus, motion changes potential energy into kinetic energy, to which the production of heat energy is attributed when friction acting between the moving object and other objects in the environment.

Ambient Heat and Ambient Cooling

Ambient cooling is a natural process that affects all objects that have ambient heat. An example is a cup of hot water cooling off due to ambient currents in the environment. In this case of the TEG, ambient currents move around the thermos and draw ambient heat from its near environment. Eventually, the thermos releases more ambient heat that is also swept away. The process continues until the thermos cools beyond 54˚C which is insufficient for power generation. Since the TEG depends on the level of the ambient heat to generate electricity, the power generated decreases below 33˚C. The ambient cooling effect is what plant manufacturers base their cooling effect on so as to reduce the cost of water cooling systems (Yang, L.J. et al. 178). With the knowledge of ambient heat and the cooling systems, the manufacturers of plant cooling radiators work with the knowledge of temperature difference between the heat source and the system to ensure that thermal disequilibrium is maintained. Therefore, with the thermal disequilibrium in place thermal gradient is increased allowing for heat transfer.

Heat Transfer

Heat transfer implies the exchange of thermal energy between two or more physical material. The rate of heat transfer is dependent on various factors including the intensity of the heat and the material that is separating the two hot media. Conduction, convection and radiation are the three basic modes of heat transfer. IN the TEG, heat transfer is by convection and conduction. Between the base of the inner vacuum structure there the head of the TEG is there is a material that is a good conductor of heat so as to maintain a high temperature needed for power generation. On the base of the TEG is a poor conductor of heat so as to limit heat los into the air. The outer material is either a poor conductor of heat or a non- conductor.

Figure 2: Heat Transfer Diagram

Conclusion

The thermodynamic generator works based on Newton’s law of cooling, which states that “the rate of change of the temperature of an object is proportional to the difference between its own temperature and the ambient temperature”. In this case, the ambient temperature is the room temperature which is also heated by the heat from the generator. Cooling of the base of the generator by ambient currents causes a reduction of the temperature of the system which has to maintain a temperature differential for power generation. But once the temperature of the source falls to the same level as that of the room temperature then no power is produced. Thus, for power to be generated, the ambient temperature must always be lower than the system temperature, and the difference must be notable.

Works Cited

Ben-Naim, Arieh. Entropy Demystified. 1st ed., Hackensack, N.J., World Scientific, 2008,.

Jawad, Abdul, et al. "First and Second Laws of Thermodynamics in Modified Ho\ v {r} ava-Lifshitz $ F (R) $ Gravity." arXiv preprint arXiv:1602.06252 (2016).

O’Sullivan, Colm T. "Newton’s law of cooling—a critical assessment." American Journal of Physics 58.10 (1990): 956-960.

Warren, N. G. Excel Preliminary Physics. 1st ed., Glebe, N.S.W., Pascal Press, 2004,.

Yang, L.J. et al. "Effects Of Ambient Winds On The Thermo-Flow Performances Of Indirect Dry Cooling System In A Power Plant". 2017,.

Appendix

Temperature v. Voltage

T (˚C)

Voltage Output (V)

90

0.789

88

0.710

86

0.693

84

0.634

82

0.596

80

0.534

78

0.517

76

0.501

74

0.480

72

0.439

70

0.395

68

0.367

66

0.320

64

0.295

62

0.257

60

0.198

58

0.139

56

0.080

54

0.021

52

0.020

50

0.010

48

0.007

46

0.004

44

0.000

T means temperature of water in the thermos

Test One: Temperature versus Voltage, Power and Current at 5V

T (˚C)

T-TR(˚C)

V

I

Power(W)

I at 5V

90

67

3.162

0.608

1.924

0.346

88

65

2.828

0.586

1.656

0.298

86

63

2.759

0.546

1.506

0.271

84

61

2.549

0.523

1.333

0.240

82

59

2.399

0.496

1.189

0.214

80

57

2.141

0.481

1.029

0.185

78

55

2.068

0.444

0.918

0.165

76

53

1.997

0.403

0.804

0.145

74

51

1.912

0.390

0.745

0.134

72

49

1.757

0.349

0.613

0.110

70

47

1.570

0.343

0.539

0.097

68

45

1.467

0.307

0.451

0.081

66

43

1.298

0.294

0.382

0.069

64

41

1.172

0.253

0.296

0.053

62

39

1.018

0.225

0.229

0.041

60

37

0.786

0.193

0.152

0.027

58

35

0.568

0.180

0.102

0.018

56

33

0.315

0.162

0.051

0.009

54

31

0.001

0.144

0.000

0.000

52

29

0.001

0.112

0.000

0.000

50

27

0.001

0.002

0.000

0.000

48

25

0.001

0.002

0.000

0.000

46

23

0.001

0.002

0.000

0.000

44

21

0.001

0.002

0.000

0.000

TR means Room temperature. TR = 23˚C; T-TR (˚C) means temperature difference

Test Two: Temperature versus Voltage, Power and Current at 5V

T (˚C)

T-TR(˚C)

V

I

Power(W)

I at 5V

90

67

3.168

0.610

1.933

0.348

88

65

2.839

0.579

1.644

0.296

86

63

2.773

0.536

1.488

0.268

84

61

2.547

0.521

1.326

0.239

82

59

2.399

0.483

1.158

0.208

80

57

2.141

0.460

0.984

0.177

78

55

2.079

0.436

0.907

0.163

76

53

2.009

0.404

0.812

0.146

74

51

1.927

0.379

0.731

0.132

72

49

1.759

0.354

0.623

0.112

70

47

1.563

0.342

0.534

0.096

68

45

1.470

0.301

0.442

0.080

66

43

1.297

0.292

0.378

0.068

64

41

1.170

0.261

0.306

0.055

62

39

1.024

0.239

0.244

0.044

60

37

0.787

0.199

0.156

0.028

58

35

0.556

0.186

0.103

0.019

56

33

0.321

0.169

0.054

0.010

54

31

0.001

0.149

0.000

0.000

52

29

0.001

0.002

0.000

0.000

50

27

0.001

0.002

0.000

0.000

48

25

0.001

0.002

0.000

0.000

46

23

0.001

0.002

0.000

0.000

44

21

0.001

0.002

0.000

0.000

TR means Room temperature. TR = 23˚C

Test Three: Temperature versus Voltage, Power and Current at 5V

T (˚C)

T-TR(˚C)

V

I

Power(W)

I at 5V

90

67

3.158

0.618

1.953

0.352

88

65

2.830

0.586

1.660

0.299

86

63

2.766

0.545

1.507

0.271

84

61

2.540

0.518

1.316

0.237

82

59

2.393

0.480

1.148

0.207

80

57

2.140

0.465

0.996

0.179

78

55

2.070

0.440

0.911

0.164

76

53

2.001

0.405

0.812

0.146

74

51

1.921

0.387

0.744

0.134

72

49

1.763

0.349

0.615

0.111

70

47

1.572

0.333

0.524

0.094

68

45

1.468

0.309

0.453

0.082

66

43

1.289

0.284

0.366

0.066

64

41

1.175

0.254

0.298

0.054

62

39

1.024

0.232

0.238

0.043

60

37

0.783

0.192

0.151

0.027

58

35

0.559

0.188

0.105

0.019

56

33

0.314

0.165

0.052

0.009

54

31

0.001

0.142

0.000

0.000

52

29

0.001

0.002

0.000

0.000

50

27

0.001

0.002

0.000

0.000

48

25

0.001

0.002

0.000

0.000

46

23

0.001

0.002

0.000

0.000

44

21

0.001

0.002

0.000

0.000

TR means Room temperature. TR = 23˚C

Test Four: Temperature versus Voltage, Power and Current at 5V

T (˚C)

T-TR(˚C)

V

I

Power(W)

I at 5V

90

67

3.158

0.606

1.913

0.344

88

65

2.827

0.586

1.658

0.298

86

63

2.758

0.543

1.497

0.269

84

61

2.535

0.519

1.315

0.237

82

59

2.386

0.495

1.182

0.213

80

57

2.149

0.476

1.023

0.184

78

55

2.066

0.458

0.946

0.170

76

53

2.003

0.418

0.837

0.151

74

51

1.914

0.386

0.738

0.133

72

49

1.759

0.354

0.622

0.112

70

47

1.582

0.340

0.539

0.097

68

45

1.463

0.318

0.465

0.084

66

43

1.288

0.303

0.390

0.070

64

41

1.168

0.271

0.316

0.057

62

39

1.034

0.224

0.232

0.042

60

37

0.790

0.209

0.165

0.030

58

35

0.550

0.184

0.101

0.018

56

33

0.307

0.162

0.050

0.009

54

31

0.001

0.137

0.000

0.000

52

29

0.001

0.002

0.000

0.000

50

27

0.001

0.002

0.000

0.000

48

25

0.001

0.002

0.000

0.000

46

23

0.001

0.002

0.000

0.000

44

21

0.001

0.002

0.000

0.000