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Supercritical and Other High-pressure Solvent Systems

Supercritical and Other High-pressure Solvent Systems

Andrew J Hunt | Thomas M Attard

(2018)

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Book Details

Abstract

Exploring the range and utility of high-pressure solvent systems across a variety of different chemical applications, this book brings together recent advances in supercritical technology and other pressurised-solvent systems. It provides an in-depth overview of the latest advances and developments and discusses the limitations and drawbacks that need to be addressed. Wherever possible, the greenness and economic viability of the different solvent systems is highlighted. This book is ideal for researchers and industrialists working in environmental science, green chemistry and biorefineries.

Table of Contents

Section Title Page Action Price
Cover Cover
Supercritical and Other High-pressure Solvent Systems: For Extraction, Reaction and Material Processing i
Preface vii
Contents ix
Chapter 1 - Introduction to High-pressure Solvent Systems 1
1.1 Green Chemistry 1
1.2 Supercritical Fluids 3
1.2.1 Supercritical Fluids: Physical Properties 6
1.2.2 Supercritical Carbon Dioxide 7
1.2.3 Subcritical and Supercritical Water 8
1.2.4 Pressurised Solvent Systems 9
1.3 Conclusions 11
References 11
Chapter 2 - Understanding Entrainer Effects in Supercritical CO2 14
2.1 Introduction 14
2.1.1 Increasing Solubility 14
2.2 The Key Ideas 16
2.2.1 Too Many (Non-)Explanations 16
2.2.2 The Right Explanation 17
2.2.3 Getting the Numbers 18
2.2.4 How Not to Do It 19
2.3 The Difficulty of Prediction 20
2.3.1 What Gives Large Gu2 Values 21
2.3.2 Modelling the Baseline Solubility in Pure scCO2 via the Chrastil Formula 21
2.3.3 Linear Enhancement Factor per Entrainer Concentration (the Sovová kav Factor) 24
2.3.4 Database of Linear Solubility Enhancement Factors 26
2.3.5 From the Linearised Sovová Enhancement Factor Model to KBIs 26
2.3.6 Entrainer Effect Viewed from kav 31
2.3.7 As Good as It Gets 32
2.4 A Plausible Theory 33
2.5 Conclusions 36
References 37
Chapter 3 - Supercritical Carbon Dioxide Extraction of Lipophilic Molecules 40
3.1 Introduction 40
3.2 Solvent Extraction Problems 41
3.3 Supercritical Fluid Extraction 45
3.3.1 Choosing the Appropriate Operating Conditions for Extraction 45
3.3.2 Pressure and Temperature 46
3.3.3 Density and Solvent Power 47
3.3.4 Use of Modifiers/Co-solvents 48
3.3.5 Flow Rate 48
3.3.6 Particle Size 48
3.3.7 Optimisation of scCO2 Extraction Processes: Experimental Design 49
3.3.8 Screening Experimental Designs 50
3.3.9 Two-level Factorial Design 51
3.3.10 Two-level Full Factorial Design 51
3.3.11 Two-level Fractional Factorial Design 52
3.3.12 Two-level Plackett–Burman Design 53
3.3.13 Optimisation Design 53
3.3.14 Taguchi Design 54
3.3.15 Star Design 55
3.3.16 Central Composite Design 55
3.3.17 Box–Behnken Design (BBD) 55
3.4 Supercritical Extraction of Waxes and Bioactive Compounds 57
3.4.1 Bioactive Compounds 62
3.5 scCO2 Fractionation 65
3.6 scCO2 Extraction of Lipids as Part of a Holistic Biorefinery 67
3.7 Supercritical Extraction in Industry: Recent Advances in the Past Few Years 68
3.8 Conclusion 70
References 70
Chapter 4 - Subcritical Water: Current Status, Advances, and Applications for Extractions, Reactions and Separations 77
4.1 Introduction 77
4.2 Subcritical Water 78
4.3 Use of Subcritical Water: Current Status 80
4.4 Water for Extractions, Reactions and Separations 83
4.4.1 Extractions 83
4.4.1.1 Phenolic Compounds 83
4.4.1.2 Carbohydrates 85
4.4.1.3 Other Compounds 88
4.4.2 Mass Transfer During Extraction 90
4.4.2.1 Main Extraction Parameters 92
4.4.2.1.1\rSolubility (Thermodynamic State).The high solubility of a solute in a solvent indicates that less amount of solvent is needed to... 92
4.4.2.1.2\rSolvent Flow Rate.The solvent flow rate parameter is directly associated with the mass transfer mode when the flow is large enou... 93
4.4.2.1.3\rProperties of Plant Matrices.The knowledge of the raw material characteristics and the solute is crucial for efficient extractio... 93
4.4.3 Separations and Decompositions 94
4.4.4 Reactions 95
4.5 Economic Issues of Subcritical Water Processes 97
4.6 Patents Survey 99
4.7 Conclusions and Future Perspectives 99
Acknowledgements 101
References 101
Chapter 5 - Supercritical Fluid Chromatography (SFC) 106
5.1 Introduction 106
5.2 Early Packed Columns 107
5.3 SFC Instrumentation 108
5.4 Mobile Phase 108
5.5 Additives 109
5.6 Solid Phase 110
5.7 Detectors 112
5.7.1 Detectors: Mobile Phase 112
5.7.1.1 Mobile Phase – No Modifier 112
5.7.1.2 Mobile Phase – Modifier 112
5.7.1.3 SFC-MS 114
5.7.2 Detectors: Type of Extract 115
5.8 Two-dimensional SFC (2D SFC) 115
5.9 Polymer Separations 117
5.9.1 Polystyrene 117
5.9.2 Polyethylene Glycol (PEG) 119
5.9.3 Polyprenol 119
5.10 Natural Product Separations 120
5.10.1 Complex Lipid Systems 120
5.10.2 Triacylglycerols (TAGs) 121
5.10.3 Carotenoids 122
5.10.4 Terpenes 122
5.10.5 Alkaloids 124
5.10.6 Phenolic Compounds 125
5.10.6.1 Coumarins 126
5.10.6.2 Cannabinoids 126
5.10.6.3 Anthraquinones 126
5.10.6.4 Flavonoids 127
5.11 Green Credentials 128
5.12 Conclusion 128
References 128
Chapter 6 - Heterogeneous Catalysis in Supercritical Carbon Dioxide 132
6.1 Introduction 132
6.2 Reactions over Heterogeneous Catalysts 137
6.2.1 Hydrogenation 137
6.2.1.1 The –C=O Bond of α,β-unsaturated Aldehydes 138
6.2.1.2 Conjugated and Isolated –C=C Bonds 147
6.2.1.3 Nitrile to Amine 151
6.2.1.4 Nitroaromatics 153
6.2.1.5 Aromatic Ring Hydrogenation 156
6.2.2 Oxidation 159
6.2.2.1 Alcohol Oxidation 160
6.2.2.2 Other Oxidising Agents 165
6.2.3 Hydrogenolysis 168
6.2.3.1 Hydrogenolysis of the Ethereal C–O Bond 168
6.2.3.2 Hydrogenolysis of the Carbonyl C–O Bond 173
6.2.3.3 Hydrogenolysis of the Carbonyl C–O Bond of Tetrahydrofurfuryl Alcohol 174
6.2.4 Dehydrogenation of Alcohols 176
6.2.5 Current Status of Some Industrially Important Reactions 178
6.2.5.1 Alkylation 178
6.2.5.2 Hydroformylation 181
6.2.5.3 Reductive Amination 182
6.3 Conclusion 183
References 184
Chapter 7 - Biocatalysis in Supercritical and Liquid Carbon Dioxide and Carbon Dioxide-expanded Liquids 191
7.1 Introduction 191
7.1.1 Supercritical and Liquid CO2 192
7.1.2 CO2-expanded Liquids 193
7.2 Biocatalyst Behaviour in High-pressure CO2-related Solvents 194
7.2.1 Nature of Enzymes 195
7.2.2 Effect of Water Content 195
7.2.3 Solubility of Enzymes and Coenzymes 197
7.2.4 Carbamate and Carbonic Acid Formation 198
7.2.5 Thermodynamic Equilibrium of Reactions 199
7.2.6 Effect of Temperature and Pressure 200
7.2.7 Effect of Changes in the Solvent Properties Caused by Tuning the Pressure and Temperature 201
7.3 Biocatalytic Reactions in Liquid and Supercritical CO2 203
7.3.1 Lipase-catalysed (Trans)Esterification, Hydrolysis and Polymerisation 203
7.3.2 Galactosidase-catalysed Transgalactosylation 206
7.3.3 Alcohol Dehydrogenase-catalysed Reduction 207
7.3.4 Carboxylase-catalysed Carboxylation 207
7.4 Biocatalytic Reactions in CO2-expanded Liquids 208
7.4.1 Conventional Organic Liquids as the Solvent Component 208
7.4.2 Green Liquids as the Solvent Component: Bio-based Liquids 210
7.4.3 Green Liquids as the Solvent Component: Water 212
7.4.4 Green Liquids as the Solvent Component: Ionic Liquids 215
7.5 Conclusions 215
References 216
Chapter 8 - Selective Hydrogenation in Carbon Dioxide-dissolved Expanded Liquid Phases 221
8.1 Introduction 221
8.2 Hydrogenation of α,β-unsaturated Carbonyl Compounds 223
8.2.1 Cinnamaldehyde 223
8.2.2 Citral 230
8.2.3 Furfural and Furfuryl Alcohol Analogues 231
8.2.4 Isophorone Analogues 234
8.2.5 Maleic Anhydride 236
8.3 Hydrogenation of Nitro Compounds 237
8.3.1 Hydrogenation in CO2-dissolved Expanded Substrates 238
8.3.2 Hydrogenation in CO2-dissolved Expanded Liquid Solvents 242
8.4 Hydrogenation of Nitrile Compounds 245
8.5 Hydrogenation of Aromatic Rings, Alkenes, Alkynes and Other Compounds 250
8.5.1 Hydrogenation of Phenol 250
8.5.2 Hydrogenation of Biphenyl, Naphthalene and Tetralin 252
8.5.3 Hydrogenation of Alkenes and Alkynes 253
8.5.4 Hydrogenation of Other Compounds 255
8.6 Conclusion 255
Acknowledgements 256
References 256
Chapter 9 - Electrochemistry in Supercritical Fluids 262
9.1 Introduction 262
9.2 A Brief Historical Review of Electrochemistry in Supercritical Fluids 263
9.3 Supercritical Fluids 264
9.3.1 Polar Supercritical Fluids 270
9.3.2 Supercritical CO2 270
9.3.3 Supercritical Hydrofluorocarbons 271
9.4 Electrolytes 272
9.4.1 Phase Behaviour 272
9.4.2 Conductivity of SCF Electrolytes 272
9.4.3 Viscosity 280
9.5 Electrodes 280
9.6 High Pressure and Temperature Systems for Supercritical Fluid Electrochemistry 282
9.7 Electrochemistry 291
9.7.1 The Double Layer in SCF Electrolytes 291
9.7.2 Electrode Kinetics and Mass Transport 292
9.8 Applications of Supercritical Fluid Electrochemistry 295
9.8.1 Electrodeposition 295
9.8.2 Electrosynthesis 297
9.9 Conclusions 297
Acknowledgements 298
References 298
Chapter 10 - Materials Processing and Recycling with Near- and Supercritical CO2-based Solvents 304
10.1 Introduction 304
10.2 Thermodynamics and Phase Behaviour Data for CO2-based Solvents 306
10.2.1 Equation of State for the Estimation of the Vapour–Liquid Equilibrium and Thermodynamic Properties 308
10.2.2 Solubility of Reagents 310
10.3 Organic Materials Processing Using CO2-based Systems 311
10.3.1 Required Equipment 312
10.3.1.1 Pumps 312
10.3.1.2 Contactor 313
10.3.1.3 Precipitation Vessel 313
10.3.1.4 Back-pressure Regulator 313
10.3.1.5 Particle Separator 314
10.3.1.6 Fluid Separator 314
10.3.2 Principles of Processes Using CO2 for Organic Material Precipitation 314
10.3.2.1 CO2 as a Solvent 314
10.3.2.2 CO2 as an Antisolvent 316
10.3.2.3 CO2 as a Solute 318
10.4 Inorganic Materials Processing Using CO2-based Systems 320
10.4.1 Continuous Synthesis of Inorganic Nanostructures in CO2-based Solvents 321
10.4.2 Deposition of Films with a Supercritical Fluid Chemical Deposition Process in a Cold Wall Reactor 323
10.4.3 Surface Engineering of Materials in CO2-based Solvents 326
10.5 Materials Recycling with Supercritical CO2 327
10.5.1 LIB Electrolyte Recovery 328
10.5.2 Heavy Metal Extraction 330
10.5.3 Polymer Recycling, Case Study of PS 331
10.5.4 New Recycling Procedures based on the Use of scCO2 331
10.5.4.1 Supercritical CO2 Leaching 331
10.5.4.2 Supercritical CO2 Delamination 332
10.6 Conclusions 333
Acknowledgements 334
References 334
Chapter 11 - Solubility and Synthesis of Polymers Using Supercritical Carbon Dioxide 340
11.1 Introduction 340
11.2 Solubility of Polymers in scCO2 341
11.2.1 Predicting the CO2 Solubility in Polymers: Theoretical and Experimental Approaches 342
11.2.1.1 Henry's Law 343
11.2.1.2 Flory–Huggins Cell Model 343
11.2.1.3 Sanchez–Lacombe Model 344
11.2.1.4 Statistical Association Fluid Theory (SAFT) 344
11.2.2 Experimental Techniques to Measure Solubility 344
11.2.2.1 Gravimetric Method 344
11.2.2.2 Manometric Method 345
11.2.2.3 Piezoelectric Method 345
11.2.2.4 Gas Chromatography (GC) 345
11.2.2.5 Spectroscopic Method 346
11.3 Plasticising Effect of CO2 346
11.4 Overview of the Synthesis of Polymers in scCO2 348
11.4.1 Step-growth Polymerisation 348
11.4.2 Chain-growth Polymerisation in scCO2 349
11.4.2.1 Homogeneous Radical Polymerisation in scCO2 350
11.4.2.2 Heterogeneous Polymerisation in scCO2 352
11.4.2.2.1\rPrecipitation Polymerisation.In precipitation polymerisation, the monomers and other components start off completely soluble in ... 352
11.4.2.2.2\rDispersion Polymerisation.This is similar to precipitation polymerisation, whereby the monomer and the initiator are completely ... 354
11.4.2.2.3\rSuspension Polymerisation.Contrary to precipitation polymerisation and dispersion polymerisation, both the monomers and resultin... 356
11.4.2.2.4\rEmulsion Polymerisation.Emulsion polymerisations typically involve a biphasic mixture (that is stirred) of water–organic solvent... 357
CO2-in-H2O Emulsion Polymerisation: Examples. As stated previously, CO2-in-H2O emulsion polymerisation leads to the formation of... 359
H2O-in-CO2 Emulsion Polymerisation: Examples. Inverse emulsion polymerisation was first reported by Beckman1397969777s group in ... 360
11.4.2.2.5\rCLRP Polymerisation in Heterogeneous Systems Involving scCO2.scCO2 is ideal for conducting heterogeneous CLRP since the monomer,... 360
RAFT. There is significant work reported in the literature covering RAFT-mediated dispersion polymerisation in scCO2, which was ... 360
NMP. Initially, NMP polymerisation in scCO2 was solely reported using styrene as the monomer in dispersion (use of a stabiliser)... 363
ATRP. Both precipitation and dispersion ATRP polymerisations have been carried out in scCO2, but in the case of the former, ther... 364
CLRP Mini-emulsion Polymerisation in scCO2. Cheng et al. performed the RAFT mini-emulsion polymerisation of styrene with trithio... 364
Other CLRP in scCO2. A dispersion reversible chain transfer catalysed polymerisation (dispersion RTCP) of MMA in scCO2 was condu... 365
11.5 Conclusion 365
References 366
Chapter 12 - Incorporation of Drugs and Metals into Aerogels Using Supercritical Fluids 374
12.1 Aerogels 374
12.2 Supercritical Impregnation 376
12.2.1 Silica Aerogels 378
12.2.2 Polysaccharide and Protein Aerogels 383
12.3 Supercritical Fluid Deposition 386
12.4 Conclusion 389
References 390
Chapter 13 - Mathematical Modelling and Computation for Rapid Expansion of Supercritical Solutions 395
13.1 Introduction 395
13.2 Ideal-gas Flow Model 396
13.2.1 Compressible Navier–Stokes Equations 396
13.2.2 Preconditioned Equations 398
13.2.3 Numerical Methods 398
13.3 Thermophysical Flow Model 399
13.3.1 Modification of Preconditioned Equations 399
13.3.2 Thermophysical Model 399
13.4 Condensation Model 401
13.4.1 General Dynamic Equation 401
13.4.2 Method of Moments 401
13.4.3 Nucleation Model 403
13.4.4 Growth Rate Model 406
13.4.5 Coagulation Model 407
13.5 RESS Simulation 409
13.6 Concluding Remarks 414
References 415
Chapter 14 - The Engineering of Continuous Hydrothermal/Solvothermal Synthesis of Nanomaterials 416
14.1 Introduction 416
14.2 Hydrothermal Synthesis 417
14.2.1 Nucleation and Growth Mechanisms during Hydrothermal Synthesis 418
14.3 The Case for Continuous Flow Methods for the Synthesis of Nanomaterials 419
14.3.1 The Road from Batch to Continuous 420
14.4 Reactor Modelling 423
14.4.1 Pseudo-fluid Modelling 423
14.4.2 Computational Fluid Dynamics (CFD) Modelling 426
14.4.3 Neutron and X-ray Measurements 428
14.4.4 Reactor Design Principles 430
14.4.4.1 Essential Features 430
14.4.4.2 Important Features 432
14.4.4.3 Desirable Features 434
14.5 Beyond T-piece Reactors 436
14.5.1 Y-piece Reactors 436
14.5.2 Tangential Swirl Reactors 436
14.5.3 Pipe-in-pipe Reactors 438
14.5.4 Mechanical Hybrid Designs 439
14.6 Scale Up 439
14.7 Economics and Life Cycle Assessment (LCA) 442
14.7.1 Production Benefits and Opportunities for CHS 443
14.8 Conclusions and Future Outlook 444
References 445
Chapter 15 - The Chemistry of Continuous Hydrothermal/Solvothermal Synthesis of Nanomaterials 449
15.1 Introduction 449
15.2 Metal Oxides 450
15.3 Metal Sulphides and Chalcogenides 455
15.4 Phosphates 460
15.5 Metals 461
15.6 Zeolites and Metal Organic Frameworks 464
15.7 Layered Double Hydroxides 467
15.8 Other Materials 468
15.9 Conclusions 468
References 469
Chapter 16 - Supercritical Water Oxidation: The Next Generation for Abatement of Unrecyclable Waste of Hazardous Nature and Complex Composition 476
16.1 Background 476
16.2 The Chemistry of Supercritical Water 479
16.3 Features and Design Considerations for the Supercritical Water Oxidation Process 480
16.3.1 Feedstock 481
16.3.2 Reactor Design and Configuration 482
16.3.3 Energy Recovery and Integration 483
16.4 Operational Problems Associated with Supercritical Water Oxidation 486
16.4.1 Salt Precipitation 486
16.4.1.1 Pressure Manipulation 487
16.4.1.2 Reactor Design Solutions 488
16.4.2 Corrosion 489
16.5 Enhancement of the SCWO Process 492
16.5.1 Multi-port Oxidant Injection 492
16.5.2 Co-fuel Assisted SCWO System 494
16.5.3 Effects of Process Enhancements on SCWO Kinetics 499
16.5.3.1 Case Study 1: Supercritical Water Oxidation of DBU in an IPA-added System 500
16.5.3.2 Case Study 2: Supercritical Water Oxidation of NH4+ in an IPA-added System 501
16.6 Performance of the SCWO System for the Treatment of Complex Waste 506
16.6.1 Case Study: Use of SCWO for Treatment of Complex Wastewater 506
16.7 Conclusions 508
References 508
Chapter 17 - Gas Expanded-liquids 512
17.1 Introduction 512
17.2 Carbon Dioxide-expanded Liquids (CXLs) 515
17.2.1 Properties 515
17.2.2 Instrumentation 518
17.3 Applications 519
17.3.1 Extraction and Biorefinery 520
17.3.2 Particle Formation 521
17.3.2.1 CO2 Acting as the Solute: Particles from a Gas-saturated Solution (PGSS) 522
17.3.2.2 CO2 Acting as an Antisolvent 523
17.3.2.2.1\rGas Antisolvent (GAS) Technique.The simplest process that uses CO2 as an antisolvent is the GAS process.9 It is particularly use... 523
17.3.2.2.2\rPrecipitation with Compressed Antisolvent (PCA) and Aerosol Solvent Extraction System (ASES).The PCA process is the reverse of t... 524
17.3.2.3 CO2 Acting as a Co-solvent: Depressurisation of an Expanded Liquid Organic Solution (DELOS) 526
17.3.2.4 Enhanced Oil Recovery 527
17.3.2.5 Other Applications 528
17.4 Conclusions and Future Trends 528
Acknowledgements 529
References 529
Chapter 18 - Use of Water and Supercritical Carbon Dioxide in Novel Methodologies for Biomass Processing 532
18.1 Introduction 532
18.2 Biomass Hydrolysis 536
18.2.1 Effect of Pre-treatment on Hemicellulose Hydrolysis 536
18.2.2 Influence of Pre-treatment on Cellulose Hydrolysis 538
18.2.3 Effect of Pre-treatment on Starchy Materials 538
18.3 Conversion of Biomass-related Monosaccharides into Value-added Products 539
18.3.1 Hexose-derived Products 540
18.3.2 Pentose-derived Products 543
18.3.3 Lignin Extraction with scCO2 547
18.4 Effect of Pre-treatment on Enzymatic Hydrolysis 548
18.5 Conclusions 554
Acknowledgements 554
References 555
Chapter 19 - Hydrothermal Events Occurring During Gasification in Supercritical Water 560
19.1 Introduction 560
19.2 Thermo-physical Properties of Supercritical Water 563
19.3 Supercritical Water Gasification 566
19.4 Degradation of Model Compounds in Hydrothermal Gasification 570
19.4.1 Carbohydrates 570
19.4.2 Lignin 572
19.4.3 Proteins 573
19.4.4 Lipids and Fatty Acids 575
19.4.5 Alcohols 576
19.4.6 Sewage Sludge 578
19.5 Conclusions 581
Acknowledgements 581
References 581
Chapter 20 - Sub- and Supercritical Water Hydrolysis Applied to Agri-food Residues 588
20.1 Introduction 588
20.2 Sub/supercritical Water Hydrolysis Process 590
20.3 Novel Developments in Sub/supercritical Water Hydrolysis Applied to Agri-food Residues 597
20.4 Future Perspectives 614
20.5 Conclusions 615
References 616
Chapter 21 - Applications of Fluids at Supercritical Pressure in the Area of Power Generation – Movements Towards Economically-viable Clean Energy 620
21.1 The Properties of Fluids at Supercritical Pressure 620
21.2 Supercritical Pressure Fluids in Power Generation Plants 622
21.2.1 How it all Began – Supercritical Pressure ‘Steam’ Generators 622
21.2.2 Power Stations Operating at Supercritical Pressure – The Benson Boiler 622
21.3 Early Research on Heat Transfer with Fluids at Supercritical Pressure 623
21.4 A Unique Study of Heat Transfer to Carbon Dioxide at Supercritical Pressure 624
21.4.1 Diffusion of Heat with Strong Non-uniformity of Fluid Properties but in the Absence of any Advection of Heat 624
21.4.2 The Initial Experiments 626
21.4.3 Further Experiments 626
21.4.4 Experiments with the Cooled Surface Uppermost 629
21.4.5 Direct Numerical Simulation of the Experiments 629
21.5 Localised Deterioration of Heat Transfer in Vertical Heated Tubes 629
21.5.1 An Early Experiment Using Supercritical Water 629
21.5.2 Experiments with Supercritical Pressure Carbon Dioxide 631
21.5.3 Examples of Localised Deterioration of Heat Transfer with Heated Tubes of Smaller Diameter 633
21.5.4 Experiments at Pressures Just Below the Critical Value 633
21.6 A Simple Model of Buoyancy-induced Partial Laminarisation 634
21.6.1 Introduction 634
21.6.2 Effect of Buoyancy in Modifying the Distribution of Shear Stress 635
21.6.3 Effect of Shear Stress Modification on the Turbulent Diffusion Heat 636
21.6.4 Explanation of the Localised Nature of the Heat Transfer Deterioration 637
21.6.5 A Simple Criterion for Partial Laminarisation 637
21.7 Turbulent Forced Convection Heat Transfer with Fluids at Supercritical Pressure 638
21.7.1 Introduction 638
21.7.2 Empirical Equations for Turbulent Forced Convection Heat Transfer to Fluids at Supercritical Pressure 639
21.7.3 An Evaluation of Some Early Equations 639
21.7.4 Similarity and Scaling in the Case of Forced Convection Heat Transfer to Fluids at Supercritical Pressure 641
21.7.5 Correlating Buoyancy-influenced and Acceleration-influenced Heat Transfer Data 641
21.8 Development of Physically Based Semi-empirical Models of Heat Transfer to Supercritical Pressure Fluids 644
21.8.1 A Revival of Interest after the Millennium in Heat Transfer to Fluids at Supercritical Pressure 644
21.8.2 A Physically Based, Semi-empirical Model of Buoyancy-influenced Turbulent Flow and Heat Transfer in Supercritical Pressure... 644
21.8.3 A Physically Based Semi-empirical Model of Impairment of Heat Transfer due to Thermally Induced Bulk Flow Acceleration 646
21.8.4 Recent Work on the Development of Extended Semi-empirical Models 648
21.9 Supercritical Transformational Electric Power Cycles 648
21.9.1 Background 648
21.9.2 Advantages of Power Conversion Cycles using Supercritical Pressure Carbon Dioxide 649
21.9.3 The Supercritical CO2 Re-compression Cycle 649
21.9.4 Other Applications of scCO2 Power Cycles 650
21.9.5 Ongoing Studies of Applications Involving scCO2 Cycles 650
21.9.6 Ongoing Work 651
21.9.7 Where are we Heading Clean Energy Production Using scCO2 Power Cycles 652
Nomenclature 652
Greek symbols 653
Subscripts 653
Superscripts 654
Appendix: Steady Turbulent Flow and Heat Transfer in Tubes 654
1 Introduction 654
2 Historical Background – Analogy Between Friction and Heat Transfer 654
3 Reynolds’s Ground Breaking Experimental Study of Turbulent Flow in Tubes 657
4 The Basis of our Present Day Approach to Turbulent Flow –Reynolds’s Dynamical Theory of Incompressible Viscous Fluids 660
5 Turbulent Flow and Heat Transfer in Tubes – the Present Picture 662
References 665
Subject Index 667