Title Details

About the Editors xv

Series Editor’s Preface xvii

List of Contributors xix

1 Utilizing Phase Separation Reactions for Enhancement of the Thermoelectric Efficiency in IV–VI Alloys 1
Yaniv Gelbstein

1.1 Introduction 1

1.2 IV–VI Alloys for Waste Heat Thermoelectric Applications 2

1.3 Thermodynamically Driven Phase Separation Reactions 6

1.4 Selected IV–VI Systems with Enhanced Thermoelectric Properties Following Phase Separation Reactions 9

1.5 Concluding Remarks 11

References 11

2 Nanostructured Materials: Enhancing the Thermoelectric Performance 15
Ngo Van Nong and Le Thanh Hung

2.1 Introduction 15

2.2 Approaches for Improving ZT 16

2.3 Recent Progress in Developing Bulk Thermoelectric Materials 18

2.4 Bulk Nanostructured Thermoelectric Materials 20

2.4.1 Bi2Te3-Based Nanocomposites 20

2.4.2 PbTe-Based Nanostructured Materials 21

2.4.3 Half-Heusler Alloys 22

2.4.4 Nanostructured Skutterudite Materials 24

2.4.5 Nanostructured Oxide Materials 26

2.5 Outlook and Challenges 28

References 29

3 Organic Thermoelectric Materials 37
Simone Fabiano, Ioannis Petsagkourakis, Guillaume Fleury, Georges Hadziioannou and Xavier Crispin

3.1 Introduction 37

3.2 Seebeck Coefficient and Electronic Structure 41

3.3 Seebeck Coefficient and Charge Carrier Mobility 44

3.4 Optimization of the Figure of Merit 45

3.5 N-Doping of Conjugated Polymers 46

3.6 Elastic Thermoelectric Polymers 49

3.7 Conclusions 49

Acknowledgments 50

References 50

4 Silicon for Thermoelectric Energy Harvesting Applications 53
Dario Narducci, Luca Belsito and Alex Morata

4.1 Introduction 53

4.1.1 Silicon as a Thermoelectric Material 53

4.1.2 Current Uses of Silicon in TEGs 54

4.2 Bulk and Thin-Film Silicon 55

4.2.1 Single-Crystalline and Polycrystalline Silicon 55

4.2.2 Degenerate and Phase-Segregated Silicon 58

4.3 Nanostructured Silicon: Physics of Nanowires and Nanolayers 61

4.3.1 Introduction 61

4.3.2 Electrical Transport in Nanostructured Thermoelectric Materials 61

4.3.3 Phonon Transport in Nanostructured Thermoelectric Materials 64

4.4 Bottom-Up Nanowires 64

4.4.1 Preparation Strategies 64

4.4.2 Chemical Vapor Deposition (CVD) 65

4.4.3 Molecular Beam Epitaxy (MBE) 66

4.4.4 Laser Ablation 66

4.4.5 Solution-Based Techniques 67

4.4.6 Catalyst Materials 67

4.4.7 Catalyst Deposition Methods 68

4.5 Material Properties and Thermoelectric Efficiency 69

4.6 Top-Down Nanowires 69

4.6.1 Preparation Strategies 69

4.6.2 Material Properties and Thermoelectric Efficiency 73

4.7 Applications of Bulk and Thin-Film Silicon and SiGe Alloys to Energy Harvesting 75

4.8 Applications of Nanostructured Silicon to Energy Harvesting 77

4.8.1 Bottom-Up Nanowires 77

4.8.2 Top-Down Nanowires 78

4.9 Summary and Outlook 81

Acknowledgments 82

References 82

5 Techniques for Characterizing Thermoelectric Materials: Methods and the Challenge of Consistency 93
Hans-Fridtjof Pernau

5.1 Introduction – Hitting the Target 93

5.2 Thermal Transport in Gases and Solid-State Materials 94

5.3 The Combined Parameter ZT-Value 97

5.3.1 Electrical Conductivity 98

5.3.2 Seebeck Coefficient 101

5.3.3 Thermal Conductivity 103

5.4 Summary 107

Acknowledgments 107

References 107

6 Preparation and Characterization of TE Interfaces/Junctions 111
Gao Min and Matthew Philips

6.1 Introduction 111

6.2 Effects of Electrical and Thermal Contact Resistances 111

6.3 Preparation of Thermoelectric Interfaces 114

6.4 Characterization of Contact Resistance Using Scanning Probe 117

6.5 Characterization of Thermal Contact Using Infrared Microscope 121

6.6 Summary 123

Acknowledgments 124

References 124

7 Thermoelectric Modules: Power Output, Efficiency, and Characterization 127
Jorge García-Canadas

7.1 Introduction 127

7.1.1 Moving from Materials to a Device 127

7.1.2 Differences in Characterization 128

7.1.3 Chapter Summary 130

7.2 The Governing Equations 130

7.2.1 Particle Fluxes and the Continuity Equation 130

7.2.2 Energy Fluxes and the Heat Equation 132

7.3 Power Output and Efficiency 136

7.3.1 Power Output 137

7.3.2 Efficiency 139

7.4 Characterization of Devices 142

7.4.1 Thermal Contacts 142

7.4.2 Additional Considerations 143

7.4.3 Constant Heat Input and Constant ΔT 144

References 145

8 Integration of Heat Exchangers with Thermoelectric Modules 147
Alireza Rezaniakolaei

8.1 Introduction 147

8.2 Heat Exchanger Design – Consideration in TEG Systems 148

8.3 Cold Side Heat Exchanger for TEG Maximum Performance 150

8.4 Cooling Technologies and Design Challenges 154

8.5 Microchannel Heat Exchanger 156

8.6 Coupled and Comprehensive Simulation of TEG System 157

8.6.1 Governing Equations 157

8.6.2 Effect of Heat Exchanger Inlet/Outlet Plenums on TEG Temperature Distribution 158

8.6.3 Modified Channel Configuration 162

8.6.4 Flat-Plate Heat Exchanger versus Cross-Cut Heat Exchanger 164

8.6.5 Effect of Channel Hydraulic Diameter 167

8.7 Power–Efficiency Map 168

8.8 Section Design Optimization in TEG System 169

8.9 Conclusion 170

Acknowledgment 170

Nomenclature 170

References 172

9 Power Electronic Converters and Their Control in Thermoelectric Applications 177
Erik Schaltz and Elena A. Man

9.1 Introduction 177

9.2 Building Blocks of Power Electronics 177

9.3 Power Electronic Topologies 179

9.3.1 Buck Converter 180

9.3.2 Boost Converter 182

9.3.3 Non-Inverting Buck Boost Converter 183

9.3.4 Flyback Converter 184

9.4 Electrical Equivalent Circuit Models for Thermoelectric Modules 185

9.5 Maximum Power Point Operation and Tracking 186

9.5.1 MPPT-Methods 187

9.6 Case Study 191

9.6.1 Specifications 192

9.6.2 Requirements 193

9.6.3 Design of Passive Components 193

9.6.4 Transfer Functions 194

9.6.5 Design of Current Controller 196

9.6.6 MPPT Implementation 196

9.6.7 Design of Voltage Controller 198

9.7 Conclusion 201

References 201

10 Thermoelectric Energy Harvesting for Powering Wearable Electronics 205
Luca Francioso and Chiara De Pascali

10.1 Introduction 205

10.2 Human Body as Heat Source for Wearable TEGs 205

10.3 TEG Design for Wearable Applications: Thermal and Electrical Considerations 208

10.4 Flexible TEGs: Deposition Methods and Thermal Flow Design Approach 212

10.4.1 Deposition Methods 212

10.4.2 Heat Flow Direction Design Approach in Wearable TEG 217

10.5 TEG Integration in Wearable Devices 218

10.6 Strategies for Performance Enhancements and Organic Materials 221

10.6.1 Organic Thermoelectric Materials 223

References 225

11 Thermoelectric Modules as Efficient Heat Flux Sensors 233
Gennadi Gromov

11.1 Introduction 233

11.1.1 Applications of Heat Flux Sensors 233

11.1.2 Units of Heat Flux and Characteristics of Sensors 234

11.1.3 Modern Heat Flux Sensors 235

11.1.4 Thermoelectric Heat Flux Sensors 236

11.2 Applications of Thermoelectric Modules 238

11.3 Parameters of Thermoelectric Heat Flux Sensors 240

11.3.1 Integral Sensitivity Sa 240

11.3.2 Sensitivity Se 241

11.3.3 Thermal Resistance RT 241

11.3.4 Noise Level 241

11.3.5 Sensitivity Threshold 241

11.3.6 Noise-Equivalent Power NEP 242

11.3.7 Detectivity D* 242

11.3.8 Time Constant ;;</;;;;> 243

11.4 Self-Calibration Method of Thermoelectric Heat Flux Sensors 243

11.4.1 Sensitivity 243

11.4.2 Values of NEP and D* 247

11.5 Sensor Performance and Thermoelectric Module Design 247

11.5.1 Dependence on Physical Properties 248

11.5.2 Design Parameters 248

11.6 Features of Thermoelectric Heat Flux Sensor Design 249

11.7 Optimization of Sensors Design 250

11.7.1 Properties of Thermoelectric Material 251

11.7.2 Parameters of Thermoelectric Module 251

11.7.3 Features of Real Design 255

11.8 Experimental Family of Heat Flux Sensors 257

11.8.1 HTX – Heat Flux and Temperature Sensors (HT – Heat Flux and Temperature) 257

11.8.2 HFX – Heat Flux Sensors without Temperature (HF – Heat Flux) 257

11.8.3 HRX-IR Radiation Heat Flux Sensors (HR – Heat Flux Radiation) 257

11.9 Investigation of Sensors Performance 259

11.9.1 General Provisions 259

11.9.2 Calibration of Sensor Sensitivity 259

11.9.3 Sensitivity Temperature Dependence 261

11.9.4 Thermal Resistance 263

11.9.5 Typical Temperature Dependence of the Seebeck Coefficient 264

11.9.6 Conclusions 264

11.10 Heat Flux Sensors at the Market 265

11.11 Examples of Applications 268

11.11.1 Microcalorimetry: Evaporation of Water Drop 268

11.11.2 Measurement of Heat Fluxes in Soil 269

11.11.3 Thermoelectric Ice Sensor 269

11.11.4 Laser Power Meters 274

References 278

12 Photovoltaic–Thermoelectric Hybrid Energy Conversion 283
Ning Wang

12.1 Background and Theory 283

12.1.1 Introduction 283

12.1.2 PV Efficiency 285

12.1.3 TEG Efficiency 285

12.1.4 PVTE Module Generated Power and Efficiency 285

12.1.5 Energy Loss 285

12.1.6 Cost 286

12.1.7 Overall Feasibility 289

12.2 Different Forms of PVTE Hybrid Systems: The State of the Art 292

12.2.1 PVTE Hybrid Systems Based on Dye-Sensitized Solar Cell (DSSC) 292

12.2.2 Dye-Sensitized Solar Cell with Built-in Nanoscale Bi2Te3 TEG 294

12.2.3 PVTE Using Solar Concentrator 294

12.2.4 Solar–Thermoelectric Device Based on Bi2Te3 and Carbon Nanotube Composites 296

12.3 Optimizations of PVTE Hybrid Systems 297

12.3.1 Geometry Optimization of Thermoelectric Devices in a Hybrid PVTE System 297

12.3.2 Enhancing the Overall Heat Conduction and Light Absorption 298

12.3.3 Fishnet Meta-Structure for IR Band Trapping for Enhancement of PVTE Hybrid Systems 299

12.3.4 Full-Spectrum Photon Management of Solar Cell Structures for PVTE Hybrid Systems 300

12.3.5 An Automotive PVTE Hybrid Energy System Using Maximum Power Point Tracking 301

12.4 Application of PVTE Hybrid Systems 302

12.4.1 Novel Hybrid Solar System for Photovoltaic, Thermoelectric, and Heat Utilization 303

12.4.2 Development of an Energy-Saving Module via Combination of PV Cells and TE Coolers for Green Building Applications 303

12.4.3 Performance of Solar Cells Using TE Module in Hot Sites 303

12.5 Summary 306

References 307

Index 311