Preface ........................................................ xi
Preface to the Third Edition xiii Preface to the Second
Edition ........................................................ xv
Preface to the First Edition ................................. xvii
Introduction .................................................. xxi
PART I FUNDAMENTALS ............................................ 1
1 Solar Radiation .............................................. 3
1.1 The Sun ................................................. 3
1.2 The Solar Constant ...................................... 5
1.3 Spectral Distribution of Extraterrestrial Radiation ..... 6
1.4 Variation of Extraterrestrial Radiation ................. 8
1.5 Definitions ............................................. 9
1.6 Direction of Beam Radiation ............................ 12
1.7 Angles for Tracking Surfaces ........................... 20
1.8 Ratio of Beam Radiation on Tilted Surface to That on
Horizontal Surface ..................................... 23
1.9 Shading ................................................ 29
1.10 Extraterrestrial Radiation on a Horizontal Surface ..... 37
1.11 Summary ................................................ 41
References .................................................. 41
2 Available Solar Radiation ................................... 43
2.1 Definitions ............................................ 43
2.2 Pyrheliometers and Pyrheliometric Scales ............... 44
2.3 Pyranometers ........................................... 48
2.4 Measurement of Duration of Sunshine .................... 53
2.5 Solar Radiation Data ................................... 54
2.6 Atmospheric Attenuation of Solar Radiation ............. 59
2.7 Estimation of Average Solar Radiation .................. 64
2.8 Estimation of Clear-Sky Radiation ...................... 68
2.9 Distribution of Clear and Cloudy Days and Hours ........ 71
2.10 Beam and Diffuse Components of Hourly Radiation ........ 74
2.11 Beam and Diffuse Components of Daily Radiation ......... 77
2.12 Beam and Diffuse Components of Monthly Radiation ....... 79
2.13 Estimation of Hourly Radiation from Daily Data ......... 81
2.14 Radiation on Sloped Surfaces ........................... 84
2.15 Radiation on Sloped Surfaces: Isotropic Sky ............ 89
2.16 Radiation on Sloped Surfaces: Anisotropic Sky .......... 91
2.17 Radiation Augmentation ................................. 97
2.18 Beam Radiation on Moving Surfaces ..................... 101
2.19 Average Radiation on Sloped Surfaces: Isotropic Sky ... 103
2.20 Average Radiation on Sloped Surfaces: KT Method ....... 107
2.21 Effects of Receiving Surface Orientation ontfr ........ 112
2.22 Utilizability ......................................... 115
2.23 Generalized Utilizability ............................. 118
2.24 Daily Utilizability ................................... 126
2.25 Summary ............................................... 132
References ................................................. 133
3 Selected Heat Transfer Topics .............................. 138
3.1 The Electromagnetic Spectrum .......................... 138
3.2 Photon Radiation ...................................... 139
3.3 The Blackbody: Perfect Absorber and Emitter ........... 139
3.4 Planck's Law and Wien's Displacement Law .............. 140
3.5 Stefan-Boltzmann Equation ............................. 141
3.6 Radiation Tables ...................................... 142
3.7 Radiation Intensity and Flux .......................... 144
3.8 Infrared Radiation Exchange between Gray Surfaces ..... 146
3.9 Sky Radiation ......................................... 147
3.10 Radiation Heat Transfer Coefficient ................... 148
3.11 Natural Convection between Flat Parallel Plates and
between Concentric Cylinders .......................... 149
3.12 Convection Suppression ................................ 154
3.13 Vee-Corrugated Enclosures ............................. 158
3.14 Heat Transfer Relations for Internal Flow ............. 159
3.15 Wind Convection Coefficients .......................... 163
3.16 Heat Transfer and Pressure Drop in Packed Beds and
Perforated Plates ..................................... 165
3.17 Effectiveness-NTU Calculations for Heat Exchangers .... 168
References ................................................. 170
4 Radiation Characteristics of Opaque Materials .............. 173
4.1 Absorptance and Emittance ............................. 174
4.2 Kirchhoff s Law ....................................... 176
4.3 Reflectance of Surfaces ............................... 177
4.4 Relationships among Absorptance, Emittance, and
Reflectance ........................................... 181
4.5 Broadband Emittance and Absorptance ................... 182
4.6 Calculation of Emittance and Absorptance .............. 183
4.7 Measurement of Surface Radiation Properties ........... 186
4.8 Selective Surfaces .................................... 188
4.9 Mechanisms of Selectivity ............................. 192
4.10 Optimum Properties .................................... 195
4.11 Angular Dependence of Solar Absorptance ............... 196
4.12 Absorptance of Cavity Receivers ....................... 197
4.13 Specularly Reflecting Surfaces ........................ 198
References ................................................. 199
5 Radiation Transmission through Glazing: Absorbed
Radiation .................................................. 202
5.1 Reflection of Radiation ............................... 202
5.2 Absorption by Glazing ................................. 206
5.3 Optical Properties of Cover Systems ................... 206
5.4 Transmittance for Diffuse Radiation ................... 211
5.5 Transmittance-Absorptance Product ..................... 213
5.6 Angular Dependence of (та) ............................ 214
5.7 Spectral Dependence of Transmittance .................. 215
5.8 Effects of Surface Layers on Transmittance ............ 218
5.9 Absorbed Solar Radiation .............................. 219
5.10 Monthly Average Absorbed Radiation .................... 223
5.11 Absorptance of Rooms .................................. 229
5.12 Absorptance of Photovoltaic Cells ..................... 231
5.13 Summary ............................................... 234
References ................................................. 234
6 Flat-Plate Collectors ...................................... 236
6.1 Description of Flat-Plate Collectors .................. 236
6.2 Basic Flat-Plate Energy Balance Equation .............. 237
6.3 Temperature Distributions in Flat-Plate Collectors .... 238
6.4 Collector Overall Heat Loss Coefficient ............... 240
6.5 Temperature Distribution between Tubes and the
Collector Efficiency Factor ........................... 254
6.6 Temperature Distribution in Flow Direction ............ 261
6.7 Collector Heat Removal Factor and Flow Factor ......... 262
6.8 Critical Radiation Level .............................. 266
6.9 Mean Fluid and Plate Temperatures ..................... 267
6.10 Effective Transmittance-Absorptance Product ........... 268
6.11 Effects of Dust and Shading ........................... 271
6.12 Heat Capacity Effects in Flat-Plate Collectors ........ 272
6.13 Liquid Heater Plate Geometries ........................ 275
6.14 Air Heaters ........................................... 280
6.15 Measurements of Collector Performance ................. 287
6.16 Collector Characterizations ........................... 288
6.17 Collector Tests: Efficiency, Incidence Angle
Modifier, and Time Constant ........................... 289
6.18 Test Data ............................................. 299
6.19 Thermal Test Data Conversion .......................... 302
6.20 Flow Rate Corrections to FK(xa)„ and FR UL ............ 305
6.21 Flow Distribution in Collectors ....................... 308
6.22 In Situ Collector Performance ......................... 309
6.23 Practical Considerations for Flat-Plate Collectors .... 310
6.24 Putting it all Together ............................... 313
6.25 Summary ............................................... 318
References ................................................. 319
7 Concentrating Collectors ................................... 322
7.1 Collector Configurations .............................. 323
7.2 Concentration Ratio ................................... 325
7.3 Thermal Performance of Concentrating Collectors ....... 327
7.4 Optical Performance of Concentrating Collectors ....... 334
7.5 Cylindrical Absorber Arrays ........................... 335
7.6 Optical Characteristics of Nonimaging Concentrators ... 337
7.7 Orientation and Absorbed Energy for CPC Collectors .... 345
7.8 Performance of CPC Collectors ......................... 349
7.9 Linear Imaging Concentrators: Geometry ................ 351
7.10 Images Formed by Perfect Linear Concentrators ......... 354
7.11 Images from Imperfect Linear Concentrators ............ 359
7.12 Ray-Trace Methods for Evaluating Concentrators ........ 361
7.13 Incidence Angle Modifiers and Energy Balances ......... 361
7.14 Paraboloidal Concentrators ............................ 367
7.15 Central-Receiver Collectors ........................... 368
7.16 Practical Considerations .............................. 369
References ................................................. 370
8 Energy Storage ............................................. 373
8.1 Process Loads and Solar Collector Outputs ............. 373
8.2 Energy Storage in Solar Process Systems ............... 375
8.3 Water Storage ......................................... 376
8.4 Stratification in Storage Tanks ....................... 379
8.5 Packed-Bed Storage .................................... 384
8.6 Storage Walls ......................................... 392
8.7 Seasonal Storage ...................................... 394
8.8 Phase Change Energy Storage ........................... 396
8.9 Chemical Energy Storage ............................... 400
8.10 Battery Storage ....................................... 402
References ................................................. 406
9 Solar Process Loads ........................................ 409
9.1 Examples of Time-Dependent Loads ...................... 410
9.2 Hot-Water Loads ....................................... 411
9.3 Space Heating Loads, Degree-Days, and Balance
Temperature ........................................... 412
9.4 Building Loss Coefficients ............................ 415
9.5 Building Energy Storage Capacity ...................... 417
9.6 Cooling Loads ......................................... 417
9.7 Swimming Pool Heating Loads ........................... 418
References ............................................ 420
10 System Thermal Calculations ................................ 422
10.1 Component Models ...................................... 422
10.2 Collector Heat Exchanger Factor ....................... 424
10.3 Duct and Pipe Loss Factors ............................ 426
10.4 Controls .............................................. 429
10.5 Collector Arrays: Series Connections .................. 431
10.6 Performance of Partially Shaded Collectors ............ 433
10.7 Series Arrays with Sections Having Different
Orientations .......................................... 435
10.8 Use of Modified Collector Equations ................... 438
10.9 System Models ......................................... 441
10.10 Solar Fraction and Solar Savings Fraction ............ 444
10.11 Summary .............................................. 445
References ................................................. 446
11 Solar Process Economics .................................... 447
11.1 Costs of Solar Process Systems ........................ 447
11.2 Design Variables ...................................... 450
11.3 Economic Figures of Merit ............................. 452
11.4 Discounting and Inflation ............................. 454
11.5 Present-Worth Factor .................................. 456
11.6 Life-Cycle Savings Method ............................. 459
11.7 Evaluation of Other Economic Indicators ............... 464
11.8 The Pi, P2 Method ..................................... 467
11.9 Uncertainties in Economic Analyses .................... 472
11.10 Economic Analysis Using Solar Savings Fraction ....... 475
11.11 Summary .............................................. 476
References ................................................. 476
PART II APPLICATIONS .......................................... 477
12 Solar Water Heating: Active and Passive .................... 479
12.1 Water Heating Systems ................................. 479
12.2 Freezing, Boiling, and Scaling ........................ 483
12.3 Auxiliary Energy ...................................... 486
12.4 ч Forced-Circulation Systems .......................... 488
12.5 Low-Flow Pumped Systems ............................... 490
12.6 Natural-Circulation Systems ........................... 491
12.7 Integral Collector Storage Systems .................... 494
12.8 Retrofit Water Heaters ................................ 496
12.9 Water Heating in Space Heating and Cooling Systems .... 497
12.10 Testing and Rating of Solar Water Heaters ............ 497
12.11 Economics of Solar Water Heating ..................... 499
12.12 Swimming Pool Heating ................................ 502
12.13 Summary .............................................. 503
References ................................................. 503
13 Building Heating: Active ................................... 505
13.1 Historical Notes ...................................... 506
13.2 Solar Heating Systems ................................. 507
13.3 CSU House III Rat-Plate Liquid System ................. 511
13.4 CSU House II Air System ............................... 513
13.5 Heating System Parametric Study ....................... 517
13.6 Solar Energy-Heat Pump Systems ........................ 521
13.7 Phase Change Storage Systems .......................... 527
13.8 Seasonal Energy Storage Systems ....................... 530
13.9 Solar and Off-Peak Electric Systems ................... 533
13.10 Solar System Overheating ............................. 535
13.11 Solar Heating Economics .............................. 536
13.12 Architectural Considerations ......................... 539
References ................................................. 541
14 Building Heating: Passive and Hybrid Methods ............... 544
14.1 Concepts of Passive Heating ........................... 545
14.2 Comfort Criteria and Heating Loads .................... 546
14.3 Movable Insulation and Controls ....................... 546
14.4 Shading: Overhangs and Wingwalls ...................... 547
14.5 Direct-Gain Systems ................................... 552
14.6 Collector-Storage Walls and Roofs ..................... 557
14.7 Sunspaces ............................................. 561
14.8 Active Collection-Passive Storage Hybrid Systems ...... 563
14.9 Other Hybrid Systems .................................. 565
14.10 Passive Applications ................................. 565
14.11 Heat Distribution in Passive Buildings ............... 571
14.12 Costs and Economics of Passive Heating ............... 571
References ................................................. 573
15 Solar Cooling .............................................. 575
15.1 Solar Absorption Cooling .............................. 576
15.2 Theory of Absorption CooUng ........................... 578
15.3 Combined Solar Heating and Cooling .................... 584
15.4 Simulation Study of Solar Air Conditioning ............ 585
15.5 Operating Experience with Solar Cooling ............... 589
15.6 Applications of Solar Absorption Air Conditioning ..... 591
15.7 Solar Desiccant Cooling ............................... 592
15.8 Ventilation and Recirculation Desiccant Cycles ........ 594
15.9 Solar-Mechanical Cooling .............................. 596
15.10 Solar-Related Air Conditioning ....................... 599
15.11 Passive Cooling ...................................... 601
References ................................................. 601
16 Solar Industrial Process Heat .............................. 604
16.1 Integration with Industrial Processes ................. 604
16.2 Mechanical Design Considerations ...................... 605
16.3 Economics of Industrial Process Heat .................. 606
16.4 Open-Circuit Air Heating Applications ................. 607
16.5 Recirculating Air System Applications ................. 611
16.6 Once-Through Industrial Water Heating ................. 613
16.7 Recirculating Industrial Water Heating ................ 615
16.8 Shallow-Pond Water Heaters ............................ 617
16.9 Summary ............................................... 619
References ................................................. 619
17 Solar Thermal Power Systems ................................ 621
17.1 Thermal Conversion Systems ............................ 621
17.2 Gila Bend Pumping System .............................. 622
17.3 Luz Systems ........................................... 624
17.4 Central-Receiver Systems .............................. 628
17.5 Solar One and Solar Two Power Plants .................. 630
References ................................................. 633
18 Solar Ponds: Evaporative Processes ......................... 635
18.1 Salt-Gradient Solar Ponds ............................. 635
18.2 Pond Theory ........................................... 637
18.3 Applications of Ponds ................................. 639
18.4 Solar Distillation .................................... 640
18.5 Evaporation ........................................... 646
18.6 Direct Solar Drying ................................... 647
18.7 Summary ............................................... 647
References ................................................. 648
PART IIІ DESIGN METHODS ....................................... 651
19 Simulations in Solar Process Design ........................ 653
19.1 Simulation Programs ................................... 653
19.2 Utility of Simulations ................................ 654
19.3 Information from Simulations .......................... 655
19.4 TRNSYS: Thermal Process Simulation Program ............ 656
19.5 Simulations and Experiments ........................... 663
19.6 Meteorological Data ................................... 663
19.7 Limitations of Simulations ............................ 666
References ................................................. 667
20 Design of Active Systems: ƒ-Chart .......................... 668
20.1 Review of Design Methods .............................. 668
20.2 The ƒ-Chart Method .................................... 669
20.3 The ƒ-Chart for Liquid Systems ........................ 673
20.4 The ƒ-Chart for Air Systems ........................... 679
20.5 Service Water Heating Systems ......................... 683
20.6 The ƒ-Chart Results ................................... 685
20.7 Parallel Solar Energy-Heat Pump Systems ............... 686
20.8 Summary ............................................... 690
References ................................................. 690
21 Design of Active Systems by Utilizability Methods .......... 692
21.1 Hourly Utilizability .................................. 693
21.2 Daily Utilizability ................................... 696
21.3 The Ø ƒ-Chart Method .................................. 699
21.4 Summary ............................................... 709
References ................................................. 710
22 Design of Passive and Hybrid Heating Systems ............... 711
22.1 Approaches to Passive Design .......................... 711
22.2 Solar-Load Ratio Method ............................... 712
22.3 Unutilizability Design Method: Direct Gain ............ 721
22.4 Unutilizability Design Method: Collector-Storage
Walls ................................................. 727
22.5 Hybrid Systems: Active Collection with Passive
Storage ............................................... 736
22.6 Other Hybrid Systems .................................. 742
References ................................................. 743
23 Design of Photovoltaic Systems ............................. 745
23.1 Photovoltaic Converters ............................... 746
23.2 PV Generator Characteristics and Models ............... 747
23.3 Cell Temperature ...................................... 757
23.4 Load Characteristics and Direct-Coupled Systems ....... 759
23.5 Controls and Maximum Power Point Trackers ............. 763
23.6 Applications .......................................... 764
23.7 Design Procedures ..................................... 765
23.8 High-Flux PV Generators ............................... 770
23.9 Summary ............................................... 771
References ................................................. 771
24 Wind Energy ................................................ 774
24.1 Introduction .......................................... 774
24.2 Wind Resource ......................................... 778
24.3 One-Dimensional Wind Turbine Model .................... 786
24.4 Estimating Wind Turbine Average Power and Energy
Production ............................................ 791
24.5 Summary ............................................... 796
References ................................................. 796
APPENDIXES .................................................... 797
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