Magnetocaloric Energy Conversion (eBook)

Preface 7
Acknowledgments 13
Contents 15
1 The Thermodynamics of Magnetocaloric Energy Conversion 21
1.1 Introduction 21
1.2 Heat, Work and the Basic Thermodynamic Relations 23
1.3 Magnetocaloric Thermodynamic Cycles 28
1.3.1 The Coefficient of Performance (COP) and Exergy Efficiency 29
1.3.2 Overview of the Basic Thermodynamic Cycles 31
1.3.2.1 The AMR Thermodynamic Cycle 31
1.3.2.2 Magnetic Thermodynamic Cycles Without Regeneration 33
References 39
2 Magnetocaloric Materials for Freezing, Cooling, and Heat-Pump Applications 42
2.1 General Criteria for the Selection of the Magnetocaloric Material 45
2.1.1 Suitable Curie Temperature of the Material 45
2.1.2 The Intensity of the Magnetocaloric Effect 46
2.1.3 The Wide Temperature Range of the Magnetocaloric Effect 46
2.1.4 Near-Zero Hysteresis of the Magnetocaloric Effect 47
2.1.5 High Thermal Conductivity and Diffusivity 47
2.1.6 Good Manufacturing Properties 47
2.1.7 High Electrical Resistivity 48
2.1.8 Good Corrosion Properties 48
2.2 Most Common Magnetocaloric Materials with a Near-Room-Temperature MCE 48
2.2.1 Gd and Its Alloys 49
2.2.2 La--Fe--Si-Based MCMs 50
2.2.3 Mn-Based MCMs 51
2.2.4 Manganites 51
2.2.5 Layered MCMs 52
2.2.6 Conclusions 53
References 54
3 Magnetic Field Sources 57
3.1 Introduction 58
3.1.1 Magnetic Field and Magnetic Induction 58
3.1.2 Magnetic Moment 61
3.1.3 Magnetization 63
3.1.4 Magnetic Field and Magnetic Induction Related to Magnetic Materials 64
3.1.5 External, Internal Magnetic Field and the Demagnetization 66
3.1.6 Magnetic Susceptibility and Permeability 68
3.1.7 Magnetic Force and Torque on a Dipolar Material 69
3.2 Permanent Magnets 70
3.2.1 Permanent Magnet Materials 75
3.2.1.1 Ceramic Materials 76
3.2.1.2 Al--Ni--Co 77
3.2.1.3 Rare-Earth Magnets 77
3.2.1.4 Nd--Fe--B Magnets 77
3.2.1.5 Sm--Co Magnets 78
3.3 Electromagnetic Coils 78
3.3.1 The Electromagnetic Coil 78
3.3.2 Superconducting Magnets 85
3.4 Permanent-Magnet Designs in Magnetic Refrigeration 90
3.4.1 Static or Moving Simple (2D) Magnet Assemblies 92
3.4.2 Static Halbach (2D) Magnet Assemblies 94
3.4.3 Rotary Halbach (2D) and Simple (2D) Magnet Assemblies 96
3.4.4 Halbach (3D) Magnet Assemblies 108
3.5 Evaluation of Different Magnet Assemblies Designed or Constructed for Magnetic Refrigeration 109
References 111
4 Active Magnetic Regeneration 114
4.1 Operation of an Active Magnetic Regenerator (Different Thermodynamic Cycles with an AMR) 116
4.1.1 Characteristics of an Ericsson-like AMR Cycle 121
4.1.2 Characteristics of a Hybrid Brayton--Ericsson-like AMR Cycle 122
4.1.3 Characteristics of a Carnot-like AMR Cycle 123
4.1.4 Maximum Specific Cooling Power in the AMR Cycle 125
4.2 Layered AMR 127
4.3 Numerical Modelling of an Active Magnetic Regenerator 128
4.3.1 A Brief Review of AMR Numerical Models 128
4.3.2 Mathematical (Physical) Model of an AMR (Basic Energy Balance Equations) 129
4.3.3 Heat Transfer and Fanning Friction Factor Correlations 139
4.3.4 Improved Modelling of an AMR (Modelling of the Additional Loss Mechanisms in an AMR) 141
4.3.4.1 The Demagnetization Field 144
4.3.4.2 The Flow Maldistribution 145
4.3.4.3 Heat Losses to the Surroundings 145
4.3.4.4 Hysteresis Losses 146
4.4 The Impact of the Operational Parameters and Geometry on the Performance of the AMR 147
4.5 The Analysis of Different AMR Thermodynamic Cycles 154
4.5.1 Numerical Investigation and Comparison of Different AMR Thermodynamic Cycles 154
4.5.2 Experimental Investigation and Comparison of Different AMR Thermodynamic Cycles 163
4.5.3 Guidelines for Future Research on AMR Thermodynamic Cycles 166
4.6 The Impact of the Heat Transfer Fluid 167
4.7 Review of Processing and Manufacturing Techniques for AMRs 171
4.7.1 Fabrication of Gd-based AMRs 171
4.7.2 Fabrication of Powder-Based (sintered) AMRs 173
4.8 Where Is the Limit for Applying a Conventional AMR Cycle? 177
References 177
5 Magnetocaloric Fluids 184
5.1 Rheology of Suspensions 185
5.2 Rheology of Magnetic Fluids 189
5.2.1 Rheology of Ferrofluids 190
5.2.1.1 Rheologic Models Applied for Ferrofluids 193
5.2.2 Rheology of Magnetorheological Fluids 197
5.2.2.1 Rheologic Models Applied for Magnetorheological Fluids 198
5.3 Ferrohydrodynamics and Heat Transfer in Magnetic Fluids 203
5.3.1 A Short Note on the Effective Thermal Conductivity 207
5.4 Review of Research on Magnetocaloric Fluids 210
5.4.1 Magnetocaloric Fluid Propulsion 210
5.4.2 Refrigeration and Heat Pumping by the Application of a Magnetocaloric Fluid 213
5.5 A Note on the Design of Magnetocaloric Refrigeration or Heat-Pump Devices Based on Magnetocaloric Fluids 215
5.5.1 Applications of Magnetorheologic Fluids (Including Magnetocaloric Suspensions) 216
5.5.1.1 Magnetorheologic Fluids as Seals or Valves 216
5.5.1.2 Magnetorheologic Fluids as Thermal Diode Mechanisms 216
5.5.1.3 Magnetorheologic Fluids as Actuators for Pump Systems 217
5.5.1.4 Magnetorheologic Magnetocaloric Fluids as Refrigerants 217
5.5.2 Applications of Ferrofluids (Including Magnetocaloric Ferrofluids) 218
5.5.2.1 Magnetocaloric Ferrofluids as Refrigerants 218
5.5.2.2 Magnetocaloric Ferrofluids in Thermal Management 219
5.5.2.3 Magnetocaloric Ferrofluids in Medicine 219
References 219
6 Special Heat Transfer Mechanisms: Active and Passive Thermal Diodes 228
6.1 Introduction 229
6.2 Active Solid-State Thermal Diodes 230
6.2.1 Thermoelectrics 230
6.2.1.1 Why Must the Efficiency of a Thermal Diode with Peltier Modules Be High? 232
6.2.2 Thermionics 238
6.2.3 Spincaloritronics 238
6.2.4 Active and Passive Mechanical Contact-Based Thermal Diodes 240
6.3 Passive Solid-State Thermal Rectificators 246
6.3.1 Bulk Mechanisms 248
6.3.1.1 Metal/Insulator Coupling 248
6.3.1.2 Thermal Strain/Warping at Interfaces 248
6.3.1.3 Thermal Potential Barrier at Interfaces 248
6.3.1.4 Temperature Dependence of the Thermal Conductivity at Interfaces 249
6.3.2 Molecular-Nanoscale Mechanisms 249
6.4 Micro Fluidic Thermal Diodes 249
6.4.1 Electrohydrodynamics 250
6.4.1.1 Electrowetting 250
6.4.1.2 Electrophoresis and Dielectrophoresis 255
6.4.1.3 Electroosmosis 256
6.4.2 Ferrohydrodynamics 257
6.4.2.1 Ferrofluid Thermal Diode that Applies the Anisotropy of Thermal Conductivity 259
6.4.2.2 Ferrofluid Thermal Diode that Applies the Magnetically Induced Fluid Flow 260
6.4.2.3 Ferrofluid Thermal Diode that Acts as the Thermal Contact Switch 260
6.4.2.4 Ferrofluid and Magnetowetting Principle 260
6.4.3 Magnetohydrodynamics 261
6.4.4 Magnetorheology and Electrorheology 263
6.4.4.1 MR or ER Thermal Diode that Applies a Magnetically Induced Fluid Flow 265
6.4.4.2 MR or ER Thermal Diode that Acts as a Thermal Contact Switch 265
6.4.4.3 MR or ER Thermal Diode that Applies the Anisotropy of Thermal Conductivity 265
6.5 Review of the Research on Thermal Diodes in Magnetic Refrigeration 265
6.6 Potential Configurations of Thermal Diodes in Magnetic Refrigeration 267
6.6.1 Single-Stage Magnetocaloric Device with Thermal Diodes 268
6.6.1.1 Active and Passive Thermal Diodes in a Single-Stage Operation 270
6.6.2 Cascade Magnetocaloric Device with Thermal Diodes 273
6.6.3 Active Magnetic Regeneration with Thermal Diodes 277
References 278
7 Overview of Existing Magnetocaloric Prototype Devices 285
7.1 Reciprocating Prototypes 286
7.1.1 USA Prototypes 286
7.1.2 Canadian Prototypes 289
7.1.3 Japanese Prototypes 290
7.1.4 Chinese Prototypes 291
7.1.5 French Prototypes 295
7.1.6 Danish Prototypes 297
7.1.7 Slovenian Prototypes 299
7.1.8 Italian Prototypes 302
7.1.9 Swiss Prototypes 302
7.1.10 Korean Prototypes 302
7.1.11 Brazilian Prototypes 303
7.1.12 Polish Prototypes 304
7.1.13 Spanish Prototypes 306
7.1.14 Conclusion 312
7.2 Rotary Prototypes 312
7.2.1 USA Prototypes 312
7.2.2 Spanish Prototypes 315
7.2.3 Japanese Prototypes 315
7.2.4 Swiss Prototypes 319
7.2.5 French Prototypes 321
7.2.6 Canadian Prototypes 323
7.2.7 Chinese Prototypes 327
7.2.8 Brazilian Prototypes 331
7.2.9 Slovenian Prototypes 333
7.2.10 Danish Prototypes 334
7.2.11 Italian Prototypes 338
7.2.12 German Prototypes 339
7.3 Conclusion 343
References 343
8 Design Issues and Future Perspectives for Magnetocaloric Energy Conversion 347
8.1 Linear AMR Magnetocaloric Devices 348
8.2 Rotary AMR Magnetocaloric Devices 354
8.2.1 Rotary Magnetocaloric Devices with Rotating AMRs 354
8.2.1.1 Axial Rotary Magnetocaloric Devices with Rotating AMRs 354
8.2.1.2 Radial Rotary Magnetocaloric Devices with Rotating AMRs 358
8.2.1.3 Azimuth Rotary Magnetocaloric Devices with Rotating AMRs 360
8.2.2 Rotary AMR Magnetocaloric Devices with Rotating Magnetic Field Sources 362
8.3 Static AMR Magnetocaloric Devices 369
8.4 AMR Devices with Thermal Diode Mechanisms 370
8.5 Devices with Magnetocaloric Fluids 372
8.6 A Note on Magnetocaloric Power Generation 373
8.6.1 How to Perform Magnetocaloric Power Generation? 373
8.6.2 Review of Magnetocaloric Power Generation 373
8.7 Future Perspectives and Guidelines for Magnetocaloric Energy Conversion 374
8.7.1 Active Magnetic Regeneration AMR (Conventional Principle) 375
8.7.2 Active Magnetic Regeneration with Thermal Diodes 375
8.7.3 Magnet Assembly and Related Motor Drive 376
8.7.4 Pumping and Valve System 377
8.7.5 Working Fluid 378
8.7.6 Power Generation 379
8.7.7 General Characteristics of Future Magnetocaloric Devices 379
References 381
9 Economic Aspects of the Magnetocaloric Energy Conversion 383
9.1 A Brief Discussion About the Market and the Costs of Nd--Fe--B Permanent Magnets 383
9.2 A Brief Discussion on the Market and the Costs of Superconducting Magnets 388
9.3 Review of Cost Analyses for Magnetocaloric Energy Conversion 393
9.4 A Note on Economic Analyses for Magnetocaloric Energy Conversion 405
References 407
10 Alternative Caloric Energy Conversions 410
10.1 Electrocaloric and Pyroelectric Energy Conversion 410
10.1.1 Introduction to the Electrocaloric Effect 411
10.1.2 Electrocaloric Materials 416
10.1.2.1 Electrocaloric Ceramic Materials 417
10.1.2.2 Electrocaloric Polymers 419
10.1.3 Review of Device Concepts and First Prototypes 420
10.1.3.1 Electrocaloric Cooling Devices: Concepts and a Theoretical Evaluation of the Performance 420
10.1.3.2 Electrocaloric Cooling Devices: First Prototypes 426
10.1.4 Introduction to the Pyroelectric Effect 435
10.1.5 Pyroelectric Materials for Energy Harvesting 437
10.1.6 Review of Device Concepts and First Prototypes for Pyroelectric Energy Harvesting 438
10.1.6.1 Pyroelectric Energy Harvesting: Concepts and a Theoretical Evaluation of the Performance 439
10.1.6.2 Pyroelectric Energy Harvesting: First Prototypes 441
10.2 Barocaloric Energy Conversion 451
10.2.1 Introduction to the Barocaloric Effect and Barocaloric Materials 451
10.3 Elastocaloric Energy Conversion 453
10.3.1 Introduction to the Elastocaloric Effect 453
10.3.2 Elastocaloric Materials 457
10.3.3 Review of Design Concepts 460
References 461
Appendix 466