Syllabus For The Subject Food Engineering

FOOD ENGINEERING

Contents

About the Authors .................................................................................................................v

Foreword .............................................................................................................................vii

Preface .................................................................................................................................. ix

CHAPTER 1 Introduction .......................................................................................................1

1.1 Dimensions .............................................................................................1

1.2 Engineering Units ...................................................................................2

1.2.1 Base Units ....................................................................................2

1.2.2 Derived Units ..............................................................................3

1.2.3 Supplementary Units ..................................................................4

1.3 System ...................................................................................................10

1.4 State of a System.................................................................................... 11

1.4.1 Extensive Properties ..................................................................12

1.4.2 Intensive Properties ..................................................................13

1.5 Density ...................................................................................................13

1.6 Concentration .......................................................................................15

1.7 Moisture Content ..................................................................................17

1.8 Temperature ...........................................................................................20

1.9 Pressure ..................................................................................................22

1.10 Enthalpy.................................................................................................26

1.11 Equation of State and Perfect Gas Law ................................................26

1.12 Phase Diagram of Water .......................................................................27

1.13 Conservation of Mass ...........................................................................29

1.13.1 Conservation of Mass for an Open System .............................30

1.13.2 Conservation of Mass for a Closed System .............................32

1.14 Material Balances ..................................................................................32

1.15 Thermodynamics ..................................................................................41

1.16 Laws of Thermodynamics .....................................................................42

1.16.1 First Law of Thermodynamics ..................................................42

1.16.2 Second Law of Thermodynamics .............................................42

1.17 Energy ...................................................................................................43

1.18 Energy Balance ......................................................................................45

1.19 Energy Balance for a Closed System ....................................................45

1.19.1 Heat ...........................................................................................45

1.19.2 Work ..........................................................................................46

1.20 Energy Balance for an Open System ....................................................55

1.20.1 Energy Balance for Steady Flow Systems .................................56

1.21 A Total Energy Balance ..........................................................................56

1.22 Power .....................................................................................................59

1.23 Area ........................................................................................................59

Problems .........................................................................................................60

List of Symbols ...............................................................................................62

Bibliography ...................................................................................................63

CHAPTER 2 Fluid Flow in Food Processing ...........................................................................65

2.1 Liquid Transport Systems ........................................................................66

2.1.1 Pipes for Processing Plants ...........................................................67

2.1.2 Types of Pumps .............................................................................68

2.2 Properties of Liquids ...............................................................................71

2.2.1 Terminology Used in Material Response to Stress ......................72

2.2.2 Density...........................................................................................72

2.2.3 Viscosity .........................................................................................73

2.3 Handling Systems for Newtonian Liquids .............................................81

2.3.1 The Continuity Equation ..............................................................81

2.3.2 Reynolds Number .........................................................................84

2.3.3 Entrance Region and Fully Developed Flow ................................88

2.3.4 Velocity Profi le in a Liquid Flowing Under Fully

Developed Flow Conditions ........................................................90

2.3.5 Forces Due to Friction ...................................................................96

2.4 Force Balance on a Fluid Element Flowing in a Pipe—Derivation

of Bernoulli Equation ............................................................................100

2.5 Energy Equation for Steady Flow of Fluids ..........................................107

2.5.1 Pressure Energy ........................................................................... 110

2.5.2 Kinetic Energy ............................................................................. 110

2.5.3 Potential Energy ..........................................................................112

2.5.4 Frictional Energy Loss .................................................................112

2.5.5 Power Requirements of a Pump .................................................115

2.6 Pump Selection and Performance Evaluation .....................................119

2.6.1 Centrifugal Pumps ......................................................................119

2.6.2 Head ............................................................................................121

2.6.3 Pump Performance Characteristics ............................................121

2.6.4 Pump Characteristic Diagram ................................................... 125

2.6.5 Net Positive Suction Head ......................................................... 126

2.6.6 Selecting a Pump for a Liquid Transport System ..................... 129

2.6.7 Affi nity Laws ............................................................................... 135

2.7 Flow Measurement ............................................................................... 136

2.7.1 The Pitot Tube ............................................................................ 140

2.7.2 The Orifi ce Meter ....................................................................... 142

2.7.3 The Venturi Meter....................................................................... 146

2.7.4 Variable-Area Meters .................................................................. 146

2.7.5 Other Measurement Methods ................................................... 147

2.8 Measurement of Viscosity .................................................................. 148

2.8.1 Capillary Tube Viscometer .................................................... 148

2.8.2 Rotational Viscometer ........................................................... 150

2.8.3 Infl uence of Temperature on Viscosity ................................. 153

2.9 Flow Characteristics of Non-Newtonian Fluids ............................... 155

2.9.1 Properties of Non-Newtonian Fluids ................................... 155

2.9.2 Velocity Profi le of a Power Law Fluid ....................................161

2.9.3 Volumetric Flow Rate of a Power Law Fluid ......................... 162

2.9.4 Average Velocity in a Power Law Fluid .................................. 163

2.9.5 Friction Factor and Generalized Reynolds Number

for Power Law Fluids ............................................................. 163

2.9.6 Computation of Pumping Requirement of

Non-newtonian Liquids ........................................................ 166

2.10 Transport of solid foods .................................................................... 169

2.10.1 Properties of Granular Materials and Powders .....................170

2.10.2 Flow of Granular Foods ......................................................... 175

Problems ...................................................................................................... 178

List of Symbols ............................................................................................ 183

Bibliography ................................................................................................ 185

CHAPTER 3 Energy and Controls in Food Processes ...........................................................187

3.1 Generation of Steam .......................................................................... 187

3.1.1 Steam Generation Systems .................................................... 188

3.1.2 Thermodynamics of Phase Change ...................................... 190

3.1.3 Steam Tables ........................................................................... 194

3.1.4 Steam Utilization ................................................................... 200

3.2 Fuel Utilization .................................................................................. 204

3.2.1 Systems ................................................................................... 206

3.2.2 Mass and Energy Balance Analysis .........................................207

3.2.3 Burner Effi ciencies ..................................................................209

3.3 Electric Power Utilization ................................................................... 210

3.3.1 Electrical Terms and Units ......................................................212

3.3.2 Ohm’s Law ..............................................................................213

3.3.3 Electric Circuits .......................................................................214

3.3.4 Electric Motors ........................................................................216

3.3.5 Electrical Controls ...................................................................217

3.3.6 Electric Lighting ......................................................................218

3.4 Process Controls in Food Processing ................................................ 220

3.4.1 Processing Variables and Performance Indicators ................ 222

3.4.2 Input and Output Signals to Control Processes ................... 224

3.4.3 Design of a Control System ................................................... 224

3.5 Sensors ................................................................................................ 232

3.5.1 Temperature ............................................................................. 232

3.5.2 Liquid Level in a Tank .............................................................. 234

3.5.3 Pressure Sensors ....................................................................... 235

3.5.4 Flow Sensors ............................................................................. 236

3.5.5 Glossary of Terms Important in Data Acquisition ................. 237

3.6 Dynamic Response Characteristics of Sensors .................................... 237

Problems .......................................................................................................241

List of Symbols ............................................................................................ 244

Bibliography ................................................................................................ 245

CHAPTER 4 Heat Transfer in Food Processing ....................................................................247

4.1 Systems for Heating and Cooling Food Products ............................... 248

4.1.1 Plate Heat Exchanger ............................................................... 248

4.1.2 Tubular Heat Exchanger .......................................................... 252

4.1.3 Scraped-surface Heat Exchanger.............................................. 253

4.1.4 Steam-infusion Heat Exchanger .............................................. 255

4.1.5 Epilogue .................................................................................... 256

4.2 Thermal Properties of Foods ................................................................ 257

4.2.1 Specifi c Heat ............................................................................. 257

4.2.2 Thermal Conductivity .............................................................. 260

4.2.3 Thermal Diffusivity .................................................................. 262

4.3 Modes of Heat Transfer ........................................................................ 264

4.3.1 Conductive Heat Transfer ........................................................ 264

4.3.2 Convective Heat Transfer ......................................................... 267

4.3.3 Radiation Heat Transfer ........................................................... 269

4.4 Steady-State Heat Transfer.....................................................................270

4.4.1 Conductive Heat Transfer in a Rectangular Slab .....................271

4.4.2 Conductive Heat Transfer through a Tubular Pipe ................ 274

4.4.3 Heat Conduction in Multilayered Systems ............................. 277

4.4.4 Estimation of Convective Heat-Transfer Coeffi cient .............. 285

4.4.5 Estimation of Overall Heat-Transfer Coeffi cient .....................302

4.4.6 Fouling of Heat Transfer Surfaces ........................................... 306

4.4.7 Design of a Tubular Heat Exchanger .......................................312

4.4.8 The Effectiveness-NTU Method for Designing Heat

Exchangers ................................................................................ 320

4.4.9 Design of a Plate Heat Exchanger ........................................... 325

4.4.10 Importance of Surface Characteristics in Radiative

Heat Transfer ............................................................................ 332

4.4.11 Radiative Heat Transfer between Two Objects ....................... 334

4.5 Unsteady-State Heat Transfer ............................................................... 337

4.5.1 Importance of External versus Internal Resistance to Heat

Transfer ..................................................................................... 339

4.5.2 Negligible Internal Resistance to Heat Transfer

(NBi _ 0.1)—A Lumped System Analysis ................................ 340

4.5.3 Finite Internal and Surface Resistance to Heat Transfer

(0.1 _ NBi _ 40) ....................................................................... 345

4.5.4 Negligible Surface Resistance to Heat Transfer (NBi _ 40) ..... 348

4.5.5 Finite Objects ............................................................................. 348

4.5.6 Procedures to Use Temperature–Time Charts .......................... 350

4.5.7 Use of fh and j Factors in Predicting Temperature in

Transient Heat Transfer ............................................................. 358

4.6 Electrical Conductivity of Foods .......................................................... 366

4.7 Ohmic Heating ..................................................................................... 369

4.8 Microwave Heating ................................................................................371

4.8.1 Mechanisms of Microwave Heating.......................................... 372

4.8.2 Dielectric Properties .................................................................. 373

4.8.3 Conversion of Microwave Energy into Heat ............................ 374

4.8.4 Penetration Depth of Microwaves ............................................ 375

4.8.5 Microwave Oven ........................................................................ 377

4.8.6 Microwave Heating of Foods .................................................... 378

Problems ...................................................................................................... 380

List of Symbols ............................................................................................ 397

Bibliography ................................................................................................ 399

CHAPTER 5 Preservation Processes ...................................................................................403

5.1 Processing Systems ............................................................................... 403

5.1.1 Pasteurization and Blanching Systems ..................................... 404

5.1.2 Commercial Sterilization Systems ............................................ 406

5.1.3 Ultra-High Pressure Systems ...................................................... 410

5.1.4 Pulsed Electric Field Systems .....................................................412

5.1.5 Alternative Preservation Systems ...............................................413

5.2 Microbial Survivor Curves .....................................................................413

5.3 Infl uence of External Agents .................................................................418

5.4 Thermal Death Time F ......................................................................... 422

5.5 Spoilage Probability ............................................................................. 423

5.6 General Method for Process Calculation ............................................ 424

5.6.1 Applications to Pasteurization .................................................. 426

5.6.2 Commercial Sterilization .......................................................... 429

5.6.3 Aseptic Processing and Packaging ............................................ 432

5.7 Mathematical Methods ........................................................................ 440

5.7.1 Pouch Processing ....................................................................... 444

Problems ...................................................................................................... 447

List of Symbols ............................................................................................ 450

Bibliography .................................................................................................451

CHAPTER 6 Refrigeration ..................................................................................................455

6.1 Selection of a Refrigerant ..................................................................... 456

6.2 Components of a Refrigeration System ............................................... 460

6.2.1 Evaporator ...................................................................................461

6.2.2 Compressor ................................................................................ 463

6.2.3 Condenser .................................................................................. 466

6.2.4 Expansion Valve ......................................................................... 468

6.3 Pressure–Enthalpy Charts .....................................................................470

6.3.1 Pressure–Enthalpy Tables .......................................................... 474

6.3.2 Use of Computer-Aided Procedures to Determine

Thermodynamic Properties of Refrigerants .............................. 475

6.4 Mathematical Expressions Useful in Analysis of

Vapor-Compression Refrigeration ....................................................... 478

6.4.1 Cooling Load.............................................................................. 478

6.4.2 Compressor ................................................................................ 480

6.4.3 Condenser .................................................................................. 480

6.4.4 Evaporator ...................................................................................481

6.4.5 Coeffi cient of Performance .........................................................481

6.4.6 Refrigerant Flow Rate ..................................................................481

6.5 Use of Multistage Systems .................................................................... 490

6.5.1 Flash Gas Removal System .........................................................491

Problems .................................................................................................... 495

List of Symbols ............................................................................................ 498

Bibliography ................................................................................................ 498

CHAPTER 7 Food Freezing .................................................................................................501

7.1 Freezing Systems ....................................................................................502

7.1.1 Indirect Contact Systems ............................................................502

7.1.2 Direct-Contact Systems ...............................................................507

7.2 Frozen-Food Properties ......................................................................... 510

7.2.1 Density......................................................................................... 510

7.2.2 Thermal Conductivity ................................................................. 511

7.2.3 Enthalpy ...................................................................................... 511

7.2.4 Apparent Specifi c Heat ...............................................................513

7.2.5 Apparent Thermal Diffusivity.....................................................513

7.3 Freezing Time.........................................................................................514

7.3.1 Plank’s Equation .........................................................................516

7.3.2 Other Freezing-Time Prediction Methods ................................ 520

7.3.3 Pham’s Method to Predict Freezing Time ................................. 520

7.3.4 Prediction of Freezing Time of Finite-Shaped Objects ............ 524

7.3.5 Experimental Measurement of Freezing Time .......................... 528

7.3.6 Factors Infl uencing Freezing Time ............................................ 528

7.3.7 Freezing Rate .............................................................................. 529

7.3.8 Thawing Time ............................................................................. 529

7.4 Frozen-Food Storage ............................................................................. 530

7.4.1 Quality Changes in Foods during Frozen Storage ................... 530

Problems ............................................................................................... 534

List of Symbols ............................................................................................ 538

Bibliography ............................................................................................... 539

CHAPTER 8 Evaporation ....................................................................................................543

8.1 Boiling-Point Elevation ........................................................................ 545

8.2 Types of Evaporators ............................................................................ 547

8.2.1 Batch-Type Pan Evaporator ....................................................... 547

8.2.2 Natural Circulation Evaporators ............................................... 548

8.2.3 Rising-Film Evaporator .............................................................. 548

8.2.4 Falling-Film Evaporator ............................................................. 549

8.2.5 Rising/Falling-Film Evaporator ................................................. 550

8.2.6 Forced-Circulation Evaporator ...................................................551

8.2.7 Agitated Thin-Film Evaporator ...................................................551

8.3 Design of a Single-Effect Evaporator ................................................... 554

8.4 Design of a Multiple-Effect Evaporator ............................................... 559

8.5 Vapor Recompression Systems ............................................................. 565

8.5.1 Thermal Recompression ............................................................ 565

8.5.2 Mechanical Vapor Recompression ............................................ 566

Problems ............................................................................................... 566

List of Symbols ............................................................................................ 569

Bibliography ............................................................................................... 569

CHAPTER 9 Psychrometrics ................................................................................................571

9.1 Properties of Dry Air..............................................................................571

9.1.1 Composition of Air .....................................................................571

9.1.2 Specifi c Volume of Dry Air ........................................................ 572

9.1.3 Specifi c Heat of Dry Air ............................................................. 572

9.1.4 Enthalpy of Dry Air .................................................................... 572

9.1.5 Dry Bulb Temperature ............................................................... 573

9.2 Properties of Water Vapor .................................................................... 573

9.2.1 Specifi c Volume of Water Vapor ................................................ 573

9.2.2 Specifi c Heat of Water Vapor ..................................................... 573

9.2.3 Enthalpy of Water Vapor ............................................................ 574

9.3 Properties of Air–Vapor Mixtures ........................................................ 574

9.3.1 Gibbs–Dalton Law ..................................................................... 574

9.3.2 Dew-Point Temperature ............................................................. 574

9.3.3 Humidity Ratio (or Moisture Content) .............................. 575

9.3.4 Relative Humidity ................................................................ 576

9.3.5 Humid Heat of an Air–Water Vapor Mixture ...................... 576

9.3.6 Specifi c Volume .................................................................... 577

9.3.7 Adiabatic Saturation of Air .................................................. 577

9.3.8 Wet Bulb Temperature.......................................................... 579

9.4 The Psychrometric Chart .................................................................. 582

9.4.1. Construction of the Chart .................................................... 582

9.4.2 Use of Psychrometric Chart to Evaluate Complex

Air-Conditioning Processes ................................................. 584

Problems ...................................................................................................... 589

List of Symbols ............................................................................................ 592

Bibliography ............................................................................................... 593

CHAPTER 10 Mass Transfer ................................................................................................595

10.1 The Diffusion Process....................................................................... 596

10.1.1 Steady-State Diffusion of Gases (and Liquids)

through Solids ...................................................................... 599

10.1.2 Convective Mass Transfer ..................................................... 600

10.1.3 Laminar Flow over a Flat Plate ............................................ 604

10.1.4 Turbulent Flow Past a Flat Plate .......................................... 608

10.1.5 Laminar Flow in a Pipe ........................................................ 608

10.1.6 Turbulent Flow in a Pipe ..................................................... 609

10.1.7 Mass Transfer for Flow over Spherical Objects ................... 609

10.2 Unsteady-State Mass Transfer ........................................................... 610

10.2.1 Transient-State Diffusion ...................................................... 611

10.2.2 Diffusion of Gases .................................................................616

Problems ....................................................................................................619

List of Symbols ..........................................................................................621

Bibliography ............................................................................................. 622

CHAPTER 11 Membrane Separation .................................................................................623

11.1 Electrodialysis Systems ..................................................................... 625

11.2 Reverse Osmosis Membrane Systems .............................................. 629

11.3 Membrane Performance ................................................................... 636

11.4 Ultrafi ltration Membrane Systems .................................................. 637

11.5 Concentration Polarization ............................................................. 639

11.6 Types of Reverse-Osmosis and Ultrafi ltration Systems .................. 645

11.6.1 Plate and Frame .................................................................... 646

11.6.2 Tubular .................................................................................. 646

11.6.3 Spiral-Wound ....................................................................... 646

11.6.4 Hollow-Fiber ........................................................................ 649

Problems ................................................................................................... 649

List of Symbols ......................................................................................... 650

Bibliography ..............................................................................................651

CHAPTER 12 Dehydration .................................................................................................653

12.1 Basic Drying Processes ..................................................................... 653

12.1.1 Water Activity ....................................................................... 654

12.1.2 Moisture Diffusion .............................................................. 657

12.1.3 Drying-Rate Curves .............................................................. 658

12.1.4 Heat and Mass Transfer ....................................................... 658

12.2 Dehydration systems ........................................................................ 660

12.2.1 Tray or Cabinet Dryers ........................................................ 660

12.2.2 Tunnel Dryers .......................................................................661

12.2.3 Puff-Drying .......................................................................... 662

12.2.4 Fluidized-Bed Drying .......................................................... 663

12.2.5 Spray Drying ........................................................................ 663

12.2.6 Freeze-Drying ....................................................................... 664

12.3 Dehydration System Design............................................................. 665

12.3.1 Mass and Energy Balance .................................................... 665

12.3.2 Drying-Time Prediction .......................................................670

Problems ................................................................................................... 680

List of Symbols ......................................................................................... 685

Bibliography .............................................................................................. 686

CHAPTER 13 Supplemental Processes ...............................................................................689

13.1 Filtration ........................................................................................... 689

13.1.1 Operating Equations ........................................................... 689

13.1.2 Mechanisms of Filtration .................................................... 695

13.1.3 Design of a Filtration System .............................................. 696

13.2 Sedimentation .................................................................................. 699

13.2.1 Sedimentation Velocities for Low-Concentration

Suspensions ......................................................................... 699

13.2.2 Sedimentation in High-Concentration Suspensions..........702

13.3 Centrifugation ...................................................................................705

13.3.1 Basic Equations .....................................................................705

13.3.2 Rate of Separation ................................................................705

13.3.3. Liquid-Liquid Separation .....................................................707

13.3.4 Particle-Gas Separation ........................................................709

13.4 Mixing ...............................................................................................709

13.4.1 Agitation Equipment ............................................................ 711

13.4.2 Power Requirements of Impellers ........................................714

Problems ....................................................................................................718

List of Symbols ..........................................................................................719

Bibliography ............................................................................................. 720

CHAPTER 14 Extrusion Processes for Foods .......................................................................721

14.1 Introduction and Background ..........................................................721

14.2 Basic Principles of Extrusion ............................................................ 722

14.3 Extrusion Systems ............................................................................. 729

14.3.1 Cold Extrusion ...................................................................... 730

14.3.2 Extrusion Cooking ................................................................731

14.3.3 Single Screw Extruders ......................................................... 732

14.3.4 Twin-Screw Extruders ........................................................... 734

14.4 Extrusion System Design .................................................................. 735

14.5 Design of More Complex Systems ................................................... 740

Problems ....................................................................................................741

List of Symbols ......................................................................................... 742

Bibliography .............................................................................................. 742

CHAPTER 15 Packaging Concepts .....................................................................................745

15.1 Introduction...................................................................................... 745

15.2 Food Protection ................................................................................ 746

15.3 Product Containment ...................................................................... 747

15.4 Product Communication ................................................................. 748

15.5 Product Convenience ....................................................................... 748

15.6 Mass Transfer in Packaging Materials .............................................. 748

15.6.1 Permeability of Packaging Material to “Fixed” Gases .........751

15.7 Innovations in Food Packaging ....................................................... 754

15.7.1 Passive Packaging ................................................................. 755

15.7.2 Active Packaging ................................................................... 755

15.7.3 Intelligent Packaging ............................................................ 756

15.8 Food Packaging and Product Shelf-life ........................................... 758

15.8.1 Scientifi c Basis for Evaluating Shelf Life.............................. 758

15.9 Summary ........................................................................................... 766

Problems ................................................................................................... 766

List of Symbols ......................................................................................... 767

Bibliography ............................................................................................. 768

Appendices ........................................................................................................................771

A.1 SI System of Units and Conversion Factors .......................................771

A.1.1 Rules for Using SI Units ...........................................................771

Table A.1.1: SI Prefi xes ........................................................................771

Table A.1.2: Useful Conversion Factors ............................................ 774

Table A.1.3: Conversion Factors for Pressure .................................... 776

A.2 Physical Properties of Foods .............................................................. 777

Table A.2.1: Specifi c Heat of Foods ................................................... 777

Table A.2.2: Thermal Conductivity of Selected Food

Products ......................................................................... 778

Table A.2.3: Thermal Diffusivity of Some Foodstuffs ...................... 780

Table A.2.4: Viscosity of Liquid Foods ...............................................781

Table A.2.5: Properties of Ice as a Function of

Temperature ................................................................... 782

Table A.2.6: Approximate Heat Evolution Rates of

Fresh Fruits and Vegetables When Stored

at Temperatures Shown ................................................. 782

Table A.2.7: Enthalpy of Frozen Foods ............................................. 784

Table A.2.8: Composition Values of Selected Foods ........................ 785

Table A.2.9: Coeffi cients to Estimate Food Properties ..................... 786

A.3 Physical Properties of Nonfood Materials ........................................ 787

Table A.3.1: Physical Properties of Metals ........................................ 787

Table A.3.2: Physical Properties of Nonmetals ................................. 788

Table A.3.3: Emissivity of Various Surfaces ....................................... 790

A.4 Physical Properties of Water and Air ................................................. 792

Table A.4.1: Physical Properties of Water at the

Saturation Pressure ........................................................ 792

Table A.4.2: Properties of Saturated Steam ....................................... 793

Table A.4.3: Properties of Superheated Steam .................................. 795

Table A.4.4: Physical Properties of Dry Air at Atmospheric

Pressure .......................................................................... 796

A.5 Psychrometric Charts ......................................................................... 797

Figure A.5.1: Psychrometric chart for high temperatures ................. 797

Figure A.5.2: Psychrometric chart for low temperatures .................. 798

A.6 Pressure-Enthalpy Data ...................................................................... 799

Figure A.6.1: Pressure–enthalpy diagram for Refi gerant 12 ............. 799

Table A.6.1: Properties of Saturated Liquid andVapor R-12 ............ 800

Figure A.6.2: Pressure–enthalpy diagram of superheated

R-12 vapor .................................................................... 803

Table A.6.2: Properties of Saturated Liquid and Vapor

R-717 (Ammonia) .......................................................... 804

Figure A.6.3: Pressure-enthalpy diagram of

superheated R-717 (ammonia) vapor ..........................807

Table A.6.3: Properties of Saturated Liquid and Vapor R-134a ...................808

Figure A.6.4: Pressure–enthalpy diagram of R-134a ......................... 811

Figure A.6.5: Pressure–enthalpy diagram of R-134a

(expanded scale) ...........................................................812

A.7 Symbols for Use in Drawing Food Engineering Process

Equipment ...........................................................................................813

A.8 Miscellaneous ......................................................................................818

Table A.8.1: Numerical Data, and Area/Volume of

Objects ..................................................................818

Figure A.8.1: Temperature at geometric center

of a sphere (expanded scale) .............................819

Figure A.8.2: Temperature at the axis of an infi nitely

long cylinder (expanded scale) ........................ 820

Figure A.8.3: Temperature at the midplane of an

infi nite slab (expanded scale) ............................821

A.9 Dimensional Analysis ........................................................................ 822

Table A.9.1: Dimensions of selected experimental

variables .............................................................. 823

Bibliography .............................................................................................. 826

Index .......................................................................................................... 829

Food Science and Technology: International Series ............................. 839

 

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