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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
- Veröffentlichungsjahr: 2017
The definitive text/reference for students, researchers and practicing engineers This book provides comprehensive coverage on Refrigeration Systems and Applications, ranging from the fundamental principles of thermodynamics to food cooling applications for a wide range of sectoral utilizations. Energy and exergy analyses as well as performance assessments through energy and exergy efficiencies and energetic and exergetic coefficients of performance are explored, and numerous analysis techniques, models, correlations and procedures are introduced with examples and case studies. There are specific sections allocated to environmental impact assessment and sustainable development studies. Also featured are discussions of important recent developments in the field, including those stemming from the author's pioneering research. Refrigeration is a uniquely positioned multi-disciplinary field encompassing mechanical, chemical, industrial and food engineering, as well as chemistry. Its wide-ranging applications mean that the industry plays a key role in national and international economies. And it continues to be an area of active research, much of it focusing on making the technology as environmentally friendly and sustainable as possible without compromising cost efficiency and effectiveness. This substantially updated and revised edition of the classic text/reference now features two new chapters devoted to renewable-energy-based integrated refrigeration systems and environmental impact/sustainability assessment. All examples and chapter-end problems have been updated as have conversion factors and the thermophysical properties of an array of materials. * Provides a solid foundation in the fundamental principles and the practical applications of refrigeration technologies * Examines fundamental aspects of thermodynamics, refrigerants, as well as energy and exergy analyses and energy and exergy based performance assessment criteria and approaches * Introduces environmental impact assessment methods and sustainability evaluation of Refrigeration Systems and Applications * Covers basic and advanced (and hence integrated) refrigeration cycles and systems, as well as a range of novel applications * Discusses crucial industrial, technical and operational problems, as well as new performance improvement techniques and tools for better design and analysis * Features clear explanations, numerous chapter-end problems and worked-out examples Refrigeration Systems and Applications, Third Edition is an indispensable working resource for researchers and practitioners in the areas of Refrigeration and Air Conditioning. It is also an ideal textbook for graduate and senior undergraduate students in mechanical, chemical, biochemical, industrial and food engineering disciplines.
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Table of Contents
Cover
Title Page
Copyright
Preface
Acknowledgments
Chapter 1: General Aspects of Thermodynamics
1.1 Introduction
1.2 Dimensions and Units
1.3 Thermodynamics
1.4 Ideal and Real Gases
1.5 Refrigerators and Heat Pumps
1.6 Psychrometrics
1.7 Concluding Remarks
Nomenclature
Study Problems
References
Chapter 2: Refrigerants
2.1 Introduction
2.2 Classification of Refrigerants
2.3 Prefixes and Decoding of Refrigerants
2.4 Secondary Refrigerants
2.5 Refrigerant–absorbent Combinations
2.6 Stratospheric Ozone Layer
2.7 Global Warming
2.8 Clean Air Act
2.9 Key Refrigerants
2.10 Selection of Refrigerants
2.11 Thermophysical Properties of Refrigerants
2.12 Lubricating Oils and their Effects
2.13 Concluding Remarks
Study Problems
References
Chapter 3: Refrigeration System Components
3.1 Introduction
3.2 History of Refrigeration
3.3 Main Refrigeration Systems
3.4 Refrigeration System Components
3.5 Compressors
3.6 Condensers
3.7 Evaporators
3.8 Throttling Devices
3.9 Auxiliary Devices
3.10 Concluding Remarks
Nomenclature
Study Problems
References
Chapter 4: Refrigeration Cycles and Systems
4.1 Introduction
4.2 Vapor-compression Refrigeration Systems
4.3 Energy Analysis of Vapor-compression Refrigeration Cycle
4.4 Exergy Analysis of Vapor-compression Refrigeration Cycle
4.5 Actual Vapor-compression Refrigeration Cycle
4.6 Air-standard Refrigeration Systems
4.7 Absorption Refrigeration Systems
4.8 Concluding Remarks
Nomenclature
Study Problems
References
Chapter 5: Advanced Refrigeration Cycles and Systems
5.1 Introduction
5.2 Multistage Refrigeration Cycles
5.3 Cascade Refrigeration Systems
5.4 Multi-effect Absorption Refrigeration Systems
5.5 Steam-jet Refrigeration Systems
5.6 Adsorption Refrigeration
5.7 Stirling Cycle Refrigeration
5.8 Thermoelectric Refrigeration
5.9 Thermoacoustic Refrigeration
5.10 Metal Hydride Refrigeration
5.11 Magnetic Refrigeration
5.12 Supermarket Refrigeration Practices
5.13 Concluding Remarks
Nomenclature
Study Problems
References
Chapter 6: Renewable Energy-based Integrated Refrigeration Systems
6.1 Introduction
6.2 Solar-powered Absorption Refrigeration Systems
6.3 Solar-powered Vapor-compression Refrigeration Systems
6.4 Wind-powered Vapor-compression Refrigeration Systems
6.5 Hydropowered Vapor-compression Refrigeration Systems
6.6 Geothermal-powered Vapor-compression Refrigeration Systems
6.7 Ocean Thermal Energy Conversion Powered Vapor-compression Refrigeration Systems
6.8 Biomass-powered Absorption Refrigeration Systems
6.9 Concluding Remarks
Nomenclature
Study Problems
Reference
Chapter 7: Heat Pipes
7.1 Introduction
7.2 Heat Pipes
7.3 Heat Pipe Applications
7.4 Heat Pipes for Electronics Cooling
7.5 Types of Heat Pipes
7.6 Heat Pipe Components
7.7 Operational Principles of Heat Pipes
7.8 Heat Pipe Performance
7.9 Design and Manufacture of Heat Pipes
7.10 Heat-transfer Limitations
7.11 Heat Pipes in Heating, Ventilating and Air Conditioning
7.12 Concluding Remarks
Nomenclature
Study Problems
References
Chapter 8: Food Refrigeration
8.1 Introduction
8.2 Food Deterioration
8.3 Food Preservation
8.4 Food Quality
8.5 Food Precooling and Cooling
8.6 Food Precooling Systems
8.7 Precooling of Milk
8.8 Food Freezing
8.9 Cool and Cold Storage
8.10 Controlled Atmosphere Storage
8.11 Refrigerated Transport
8.12 Respiration (Heat Generation)
8.13 Transpiration (Moisture Loss)
8.14 Cooling Process Parameters
8.15 Analysis of Cooling Process Parameters
8.16 Fourier–Reynolds Correlations
8.17 Cooling Heat-transfer Parameters
8.18 Conclusions
Nomenclature
Study Problems
References
Chapter 9: Food Freezing
9.1 Introduction
9.2 Food Freezing Aspects
9.3 Quick Freezing
9.4 Enthalpy
9.5 Crystallization
9.6 Moisture Migration
9.7 Weight Loss
9.8 Blanching
9.9 Packaging
9.10 Quality of Frozen Foods
9.11 Food Freezing Process
9.12 Freezing Point
9.13 Freezing Rate
9.14 Freezing Times
9.15 Freezing Equipment
9.16 Ice Making
9.17 Thawing
9.18 Freeze-drying
9.19 Conclusions
Nomenclature
Study Problems
References
Chapter 10: Environmental Impact and Sustainability Assessment of Refrigeration Systems
10.1 Introduction
10.2 Environmental Concerns
10.3 Energy and Environmental Impact
10.4 Dincer's Six Pillars
10.5 Dincer's 3S Concept
10.6 System Greenization
10.7 Sustainability
10.8 Energy and Sustainability
10.9 Exergy and Sustainability
10.10 Concluding Remarks
Study Problems
References
Appendix A: Conversion Factors
Appendix B: Thermophysical Properties
Appendix C: Food Refrigeration Data
Index
End User License Agreement
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Guide
cover
Table of Contents
Preface
Begin Reading
List of Illustrations
Chapter 1: General Aspects of Thermodynamics
Figure 1.1 Illustration of pressure relationships.
Figure 1.2 A general closed system with heat and work interactions.
Figure 1.3 A general steady-flow control volume with mass, heat, and work interactions.
Figure 1.4 An illustration of Dincer's six-step approach.
Figure 1.5 A closed system.
Figure 1.6 A closed system for Example 1.1.
Figure 1.7 An open system.
Figure 1.8 A schematic illustration of compressor.
Figure 1.9 The state-change diagram of water.
Figure 1.10 Temperature–volume diagram for the phase change of water.
Figure 1.11 Generalized compressibility chart for simple substances [5].
Figure 1.12 Representation of four different polytropic processes on a pressure–volume diagram.
Figure 1.13 (a) The vapor-compression refrigeration cycle. (b) Simplified schematic of refrigeration cycle.
Figure 1.14 (a) A schematic illustration of refrigerator and (b)
T-s
diagram of the Carnot refrigeration cycle.
Figure 1.15 The COP of a reversible refrigerator as a function of
T
L
.
T
H
is taken as 298 K.
Figure 1.16 The COP of a reversible refrigerator as a function of
T
H
.
T
L
is taken as 273 K.
Figure 1.17 A single-flash geothermal power plant for two cases: (a) without reinjection and (b) with reinjection.
Figure 1.18 Comparisons of (a) exergy and anergy contents, and (b) energy and exergy efficiencies for Cases 1 and 2.
Figure 1.19 House heating options: (a) an electric heater and (b) a heat pump.
Figure 1.20 Comparisons of (a) work requirements and (b) exergy efficiencies for Cases 1 and 2.
Figure 1.21 Representation of dew point temperature on a
T–s
diagram.
Figure 1.22 Illustration of (a) a dry-bulb thermometer and (b) a wet-bulb thermometer.
Figure 1.23 An adiabatic saturation process.
Figure 1.24 Schematic of the system.
Figure 1.26 A psychrometric chart.
Figure 1.26 Some processes on the psychrometric chart: (a) cooling and heating, (b) dehumidification, (c) cooling and dehumidification, (d) adiabatic humidification, (e) chemical dehumidification, and (f) mixture of two moist air flows.
Figure 1.27 (a) A simple heating process and (b) illustration of the process in the chart.
Figure 1.28 (a) A simple cooling process and (b) illustration of the process in the chart.
Figure 1.29 (a) A heating with humidification process and (b) illustration of the process in the chart.
Figure 1.30 (a) A cooling with dehumidification process and (b) illustration of the process in the chart.
Figure 1.31 (a) A simple adiabatic mixing process and (b) illustration of the process in the chart.
Chapter 2: Refrigerants
Figure 2.1 A schematic representation of stratospheric ozone depletion.
Figure 2.2 A schematic representation of the global warming by greenhouse effect.
Figure 2.3 Comparison of CIRA scenarios with IPCC RCPs: (a): greenhouse gas emissions, (b) radiative forcing, and (c) CO
2
concentration (
Source
: Adpated from Critchell 1912).
Figure 2.4 Variations in global mean temperature with and without global greenhouse gas mitigation (reference case) (
Source
: Adpated from Critchell 1912).
Figure 2.5 Variations in global mean sea level from 1990 with and without global greenhouse gas mitigation (
Source
: Adpated from Critchell 1912).
Figure 2.6
T–s
diagram of R-134a.
Figure 2.7
T–s
diagram of R-123.
Figure 2.8
T–s
diagram of R-404A.
Figure 2.9
T–s
diagram of R-507A.
Figure 2.10
T–s
diagram of R-747.
Figure 2.11
T–s
diagram of R-290.
Figure 2.12
T–s
diagram of R-744.
Chapter 3: Refrigeration System Components
Figure 3.1 A thermodynamic system acting as a refrigerator.
Figure 3.2 Compressor types. Heap [11]. Reproduced with permission of Elsevier.
Figure 3.3 A typical hermetic reciprocating compressor. Courtesy of Tecumseh Products Co.
Figure 3.4 New, highly efficient compact coil air-cooled condensing units using hermetic compressors. Courtesy of Tecumseh Products Co.
Figure 3.5 Semi-hermetic reciprocating compressors: (a) single-stage and (b) two-stage. Courtesy of Bitzer Kühlmaschinenbau GmbH.
Figure 3.6 (a) Open-type reciprocating compressor and (b) air-cooled condensing unit with an open-type reciprocating compressor. Courtesy of Bitzer Kühlmaschinenbau GmbH.
Figure 3.7 An internal view of a V-type six-cylinder reciprocating compressor. Courtesy of Grasso Products b.v.
Figure 3.8 A rolling-piston rotary compressor.
Figure 3.9 Cutaway view of a rotary vane compressor. Courtesy of Pneumofore SpA.
Figure 3.10 Screw compressor: (a) dual rotor and (b) single rotor. Duncan [12]. Reproduced with permission of ASHRAE.
Figure 3.11 A large-capacity double-screw compressor: (a) complete view and (b) internal view. Courtesy of Grasso Products b.v.
Figure 3.12 Internal view of a hermetic rotary screw compressor. Courtesy of Hartford Compressors.
Figure 3.13 A hermetic scroll compressor: (a) complete view, (b) cutaway view, and (c) internal view. Courtesy of the Carlyle Compressor Company.
Figure 3.14 (a) Cutaway view of a centrifugal compressor. (b) A chiller unit with centrifugal compressor. Courtesy of the Trane Company.
Figure 3.15 A centrifugal compressor. Courtesy of York International.
Figure 3.16 Cutaway view of a centrifugal compressor using magnetic bearings. Courtesy of York International.
Figure 3.17 A compressor considered for analysis.
Figure 3.18 Compressor performance profiles at different evaporator and condenser temperatures. DETR 1990. Reproduced with permission of Wiley.
Figure 3.19
T–s
diagram for R-134a as considered in Example 3.1.
Figure 3.20 Various water-cooled condensers. Courtesy of the Standard Refrigeration Company.
Figure 3.21 A typical air-cooled condenser. Courtesy of the Trane Company.
Figure 3.22 (a) An evaporative condenser and (b) a counterflow cooling tower. Courtesy of Baltimore Aircoil International.
Figure 3.23 (a) Air-cooled condenser and (b) water-cooled condenser for thermodynamic analysis.
Figure 3.24 A shell-tube evaporator. Bejan [18]. Reproduced with permission of Wiley.
Figure 3.25 Air coolers: (a) room and (b) large-scale industrial. Courtesy of Super Radiator Coils.
Figure 3.26 Evaporators considered for thermodynamic analysis: (a) refrigerant absorbing heat from a space and (b) refrigerant absorbing heat from water.
Figure 3.27 An electronic expansion valve. 1, Temperature sensor; 2, external equalizer; 3, from condenser; 4, to coil. Courtesy of Danfoss A/S.
Figure 3.28 A practical vapor compression refrigeration system with all control devices. Courtesy of ALCO Controls.
Figure 3.29 A throttling valve considered for mass and energy analysis.
Figure 3.30 An accumulator. Courtesy of Standard Refrigeration Company.
Figure 3.31 Receivers: (a) horizontal design and (b) vertical design. Courtesy of the Standard Refrigeration Company.
Figure 3.32 A coalescing oil separator. Courtesy of the Standard Refrigeration Company.
Figure 3.33 A defrost controller with timer. Courtesy of the Hansen Technologies Corporation.
Chapter 4: Refrigeration Cycles and Systems
Figure 4.1 (a) A basic vapor-compression refrigeration system, (b) its
T–s
diagram, and (c) its log
P–h
diagram.
Figure 4.2 An ideal vapor-compression refrigeration system for analysis and its temperature–entropy diagram.
Figure 4.3 Temperature–entropy diagram of the vapor-compression refrigeration cycle considered in Example 4.1.
Figure 4.4 Temperature–entropy diagram of the vapor-compression refrigeration cycle considered in Example 4.2.
Figure 4.5 An actual vapor-compression refrigeration system and its
T–s
diagram.
Figure 4.6 A typical commercial refrigerating unit. 1, Evaporator inlet; 2, evaporator outlet; 3, accumulator; 4, compressor; 5, condenser inlet; 6, condenser outlet; 7, receiver outlet; 8, heat exchanger; 9, liquid line strainer/drier; 10, expansion valve; 11, thermostat; 12, compressor crankcase heater; 13, high- and low-pressure cutout. Courtesy of Tecumseh Products Co.
Figure 4.7 (a) A vapor-compression refrigeration system with a heat exchanger for superheating and subcooling, (b) its
T–s
diagram, and (c) its log
P–h
diagram.
Figure 4.8 A subcooler. Courtesy of Standard Refrigeration Company.
Figure 4.9 An industrial air purger. Courtesy of Hansen Technologies Corporation.
Figure 4.10 A basic refrigeration system with multipoint purger. Courtesy of Armstrong International, Inc.
Figure 4.11 Temperature–entropy diagram of the vapor-compression refrigeration cycle considered in the solution of Example 4.4a.
Figure 4.12 Temperature–entropy diagram of the ideal vapor-compression refrigeration cycle considered in Example 4.4b.
Figure 4.13 (a) A twin refrigeration system and its components. Comparison of (b) a twin refrigeration system with (c) a conventional no-frost system. Courtesy of Samsung Electronics.
Figure 4.14 (a) A basic air-standard refrigeration cycle and (b) its
T–s
diagram.
Figure 4.15 (a) An air-standard refrigeration cycle using a heat exchanger and (b) its
T–s
diagram.
Figure 4.16 The gas refrigeration system with a regenerator considered in Example 4.5.
Figure 4.17 Temperature–entropy diagram of the gas refrigeration cycle considered in Example 4.5.
Figure 4.18 Temperature–entropy diagram of the simple gas refrigeration cycle considered in Example 4.5d.
Figure 4.19 (a) An ARS of 2500 kW at −15 °C installed in a meat factory in Spain. (b) An ARS of 2700 kW at −30 °C installed in a refinery in Germany. (c) An ARS of 1400 kW at −28 °C installed in a margarine factory in the Netherlands. Courtesy of Colibri b.v.-Stork Thermeq b.v.
Figure 4.20 A basic ARS.
Figure 4.21 A practical ammonia–water ARS.
Figure 4.22 The basic ARS considered in Example 4.6.
Figure 4.23 The system used to develop the reversible COP of an absorption-refrigeration system.
Figure 4.24 A three-fluid ARS.
Figure 4.25 A single-effect ARS.
Figure 4.26 A double-effect ARS.
Figure 4.27 (a) The steam ejector recompression ARS and (b) its
P–T–C
diagram [9]. Reprinted with permission from Elsevier Science.
Figure 4.28 The electrochemical ARS adapted from [[11]].
Figure 4.29 Absorption-augmented engine-driven refrigeration system adapted from [[12]].
Figure 4.30 An R-22 and DMETEG ARS adapted from [[14]]. Reprinted with permission from Elsevier Science.
Figure 4.31 Enthalpy-weight fraction (concentration) diagram for the pair of R-22 and DMETEG [14]. Reprinted with permission from Elsevier Science.
Figure 4.32 Variation of COP versus (a) evaporator temperature and (b) generator temperature [14]. Reprinted with permission from Elsevier Science.
Figure 4.33 The lithium bromide–water ARS used in the model development adapted from [[17]].
Figure 4.34 Enthalpy–concentration diagram for lithium bromide–water combinations [18]. Reprinted with permission from ASHRAE.
Figure 4.35 Variations of absorber, pump, generator, condenser, and evaporator capacities versus mass flow rate of weak solution (a) at
T
G
= 90 °C and (b) at
T
G
= 100 °C [17].
Figure 4.36 The ammonia–water ARS [19]. Reprinted with permission from Elsevier Science.
Figure 4.37 Temperature–concentration diagram of ammonia–water mixture [18]. Reprinted with permission from ASHRAE.
Figure 4.38 Variation of (a) COP and (b) exergetic COP (ECOP) with generator temperature [19]. Reprinted with permission from Elsevier Science.
Figure 4.39 Variation of COP with evaporation temperature at various condensation temperature ranges. Courtesy of Colibri b.v.-Stork Thermeq b.v.
Chapter 6: Renewable Energy-based Integrated Refrigeration Systems
Figure 6.1 A solar thermal-based absorption cooling system.
Figure 6.2 A PV-based vapor-compression refrigeration cycle.
Figure 6.3 A wind-energy-based vapor-compression refrigeration cycle.
Figure 6.4 A hydropower-based vapor-compression refrigeration cycle.
Figure 6.5 A geothermal-energy-based vapor-compression refrigeration cycle.
Figure 6.6 An OTEC-based vapor-compression refrigeration cycle.
Figure 6.7 A biomass-based absorption refrigeration cycle.
Figure 6.8 A schematic diagram of the integrated system.
Figure 6.9 Exergy destruction rates of selected units of the integrated system.
Figure 6.10 The effect of ambient temperature on energetic and exergetic COPs.
Figure 6.11 The effect of ambient temperature on the energy and exergy efficiencies of the overall system.
Chapter 7: Heat Pipes
Figure 7.1 Two basic heat pipe configurations: (a) thermosiphon and (b) capillary driven.
Figure 7.2 A cutaway view of a cylindrical heat pipe. Courtesy of Los Alamos National Laboratory. Copyright © 1998–2002 The Regents of the University of California.
Figure 7.3 (a) The heat pipe connected to the keyboard setup. (b) The setup of the heat pipe connected to the back screen. Adapted from [6].
Figure 7.4 (a) A customized heat pipe unit, especially developed for cooling with natural air (for a total power of 1 kW, with 7.5 kV Al
2
O
3
insulators, being used on onboard equipment in a subway train). (b) A stack of 7.5 kV insulated heat pipe coolers (with Al
2
O
3
insulators) designed for natural air cooling of a pair of thyristors for onboard equipment in a subway train. Light construction with aluminum evaporator and fins. (c) A stack of noninsulated heat pipe sinks designed to cool a pair of thyristors with forced ventilation, mounted with special clamping equipment. The equipment is intended for use in conjunction with an AC mill drive. Courtesy of Bosari Thermal Management s.r.l.
Figure 7.5 (a) An insulated water cooler. (b) A heat exchanger designed for the natural air cooling of a sealed container. Courtesy of Bosari Thermal Management s.r.l.
Figure 7.6 A micro heat pump [3].
Figure 7.7 A heat pipe structure. Courtesy of Heat Pipe Technology, Inc.
Figure 7.8 Temperature ranges of some heat pipe working fluids [3].
Figure 7.9 Wick structures [7]. Reproduced by permission of Flomerics, Inc.
Figure 7.10 Some common heat pipe wicking configurations and their structures: (a) simple homogeneous, (b) current composite, and (c) advanced designs [3].
Figure 7.11 Performance curves: (a) for gravity-aided operation, (b) for horizontal operation, and (c) for various heights against gravity. Courtesy of Thermacore International, Inc.
Figure 7.12 Thermal resistance network for a heat pipe. Courtesy of Thermacore International, Inc.
Figure 7.13 Heat pipe design flow chart. Adapted from [3].
Figure 7.14 Heat pipe system for dehumidification. Courtesy of Heat Pipe Technology, Inc.
Figure 7.15 An indoor dehumidifier with heat pipes. Courtesy of Heat Pipe Technology Inc.
Figure 7.16 An energy recovery heat pipe. Courtesy of Heat Pipe Technology, Inc.
Figure 7.17 Three configurations of energy recovery heat pipes: (a) over-and-under horizontal air streams with the heat pipe in a vertical plane, (b) side-by-side vertical air streams with the heat pipe in a horizontal plane, (c) side-by-side horizontal air streams with the heat pipe in a vertical plane. Courtesy of Heat Pipe Technology, Inc.
Chapter 8: Food Refrigeration
Figure 8.1 Energy coefficient data for four types of precooling systems. Adapted from Thompson and Chen [12].
Figure 8.2 Schematic of a hydrocooling system: 1, evaporator; 2, compressor; 3, condenser; 4, expansion valve; 5, cooling tank; 6, polyethylene crate; 7, product; 8, water inlet; 9, water flow; 10, water exit; 11, water circulation pump; FM, flow meter; TC, thermocouple; all dimensions in mm [9].
Figure 8.3 A large-scale hydrocooling system. Courtesy of Ag Refrigeration.
Figure 8.4 A hydrocooling system using artifical ice blocks as a source of cooling: 1, air intake; 2, mobile structure; 3, water supply; 4, ice melting system; 5, ice block; 6, plastic liner; 7, air outlet; 8, overflow channel; 9, pumps; 10, control valve; 11, upper precooler reservoir; 12, vegetables; 13, lower precooler reservoir. Adapted from [17].
Figure 8.5 Side view of the outdoor ice pond and the storage facility: 1, 1.12 kW pump; 2, priming valve; 3, heating cable; 4, sand filter; 5, heater; 6, insulation. Adapted from [17].
Figure 8.6 Schematic of the vegetable storage facility using natural snow as source of cooling. Adapted from [17].
Figure 8.7 Schematic of a forced-air cooling system: 1, cooling chamber; 2, product; 3, thermostat; 4, low-pressure steam input; 5, cold-water heat exchanger; 6, steam heat exchanger; 7, radial fan; 8, fan speed controller; 9, water pump; 10, water tank; 11, evaporator; 12, thermostatic expansion valve; 13, thermostat; 14, air-cooled condenser; 15, presostat; 16, compressor; 17, solenoid valve; 18, valve; 19, polyethylene crate. Dincer 1995. Reproduced with permission of Elsevier.
Figure 8.8 A forced-air precooling room with one air unit per precooling station. Courtesy of Ag Refrigeration.
Figure 8.9 A portable forced-air precooling room. Courtesy of Ag Refrigeration.
Figure 8.10 Precooling and storage in one room. Courtesy of the South Australian Research and Development Institute.
Figure 8.11 Box venting. Courtesy of the South Australian Research and Development Institute.
Figure 8.12 Stacking: (a) straight and (b) cross. Courtesy of the South Australian Research and Development Institute.
Figure 8.13 Tunnel forced-air cooling using a free-standing fan. Adapted from Watkins 1990.
Figure 8.14 Bin stacking for tunnel cooling. Courtesy of the South Australian Research and Development Institute.
Figure 8.15 (a) Serpentine cooling configuration. (b) A cross-sectional view of serpentine cooling with multiple columns. Courtesy of the South Australian Research and Development Institute.
Figure 8.16 Air channel dimensions. Courtesy of the South Australian Research and Development Institute.
Figure 8.17 A hydraircooling system.
Figure 8.18 A wet-air cooling system. Helsen 1989. Reproduced with permission of Wiley.
Figure 8.19 (a) A vacuum cooler with ammonia refrigeration. (b) A trailer mounted mobile vacuum cooler. Courtesy of Ag Refrigeration.
Figure 8.20 An evaporative precooling system. [29]. Reproduced with permission of Elsevier.
Figure 8.21 An electric-free cooler system for precooling milk. Courtesy of Nutrifrais SA.
Figure 8.22 A cross-sectional view of a prefabricated panel cold-storage plant.
Figure 8.23 Cross-section of the cold store facility. CADDED [37].
Figure 8.24 (a) The PV cold store. (b) Cold chamber details [38]. Reproduced with permisssion of Wiley.
Figure 8.25 Apples under CAS. Courtesy of Cold Storage Nelson Ltd.
Figure 8.26 The quality of food product as a function of time: NS, no storage; CAS, cold-air storage; CCAS, cold controlled atmosphere storage. Adapted from [34].
Figure 8.27 The PRISM Alpha Membrane Separator [34]. Reproduced with permission of Taylor & Francis.
Figure 8.28 Representation of significant factors affecting the transpiration of fresh produce. Adapted from Sastry [56].
Figure 8.29 Cooling curve representing cooling times.
Figure 8.30 Measured and regressed dimensionless center temperatures: (a) for an individual pear and (b) for an individual tomato [59]. Reproduced with permission of Wiley.
Figure 8.31 Fourier–Reynolds graph for half cooling times of fruits and vegetables subject to air cooling [61]. Reproduced with permission of Elsevier.
Figure 8.32 Fourier–Reynolds graph for seven-eighths cooling times of fruits and vegetables subject to air cooling [61]. Reproduced with permission of Elsevier.
Figure 8.33 Heat-transfer coefficient versus cooling coefficient for hydrocooling of fruits and vegetables [100]. Reproduced with permission of Wiley.
Figure 8.34 Heat-transfer coefficient versus cooling coefficient for forced-air cooling of fruits and vegetables [100]. Reproduced with permission of Wiley.
Figure 8.35 Experimental and theoretical dimensionless center temperature distributions of ISP, ICP, and SP samples.
Figure 8.36 Nusselt–Dincer diagram for food products cooled in a forced-air flow [109]. Reproduced with permission of Wiley.
Chapter 9: Food Freezing
Figure 9.1 Freezing profiles of water and an aqueous solution.
Figure 9.2 A belt-type steam blancher. Courtesy of Alard Equipment Corp.
Figure 9.3 A double-spray blancher. Adapted from Poulsen [5].
Figure 9.4 T–TT profiles of some frozen foods.
Figure 9.5 Flowcharts for freezing fruits and vegetables.
Figure 9.6 Experimental freezing profile on a semi-log scale.
Figure 9.7 A packaged tunnel freezer and its process flow schematic. Courtesy of Advanced Equipment Inc.
Figure 9.8 A modular tunnel freezer and its process flow schematic. Courtesy of Advanced Equipment Inc.
Figure 9.9 A multipass tunnel freezer. Courtesy of Advanced Equipment Inc.
Figure 9.10 A contact belt tunnel freezer. Courtesy of Advanced Equipment Inc.
Figure 9.11 A drag thru doly tunnel freezer. Courtesy of Advanced Equipment Inc.
Figure 9.12 A packaged spiral freezer. Courtesy of Advanced Equipment Inc.
Figure 9.13 A site-built spiral freezer. Courtesy of Advanced Equipment Inc.
Figure 9.14 A trolley freezing system. Courtesy of Advanced Equipment Inc.
Figure 9.15 A packaged-tray freezer. Courtesy of Advanced Equipment Inc.
Figure 9.16 (a) Impingement jets of air. (b) Flat product freezer using impingement jet technology. Courtesy of Frigoscandia Equipment AB.
Figure 9.17 A liquid nitrogen immersing-type cryogenic freezing system. Courtesy of Air Products and Chemicals, Inc.
Figure 9.18 A flow chart for general freeze-drying of food products.
Figure 9.19 Pressure–volume–temperature diagram for water showing sublimation of ice.
Figure 9.20 Freeze-drying in a slab.
Figure 9.21 Typical freeze-drying curve of a moist product.
Figure 9.22 Batch-type contact freeze-dryer. Courtesy of Oregon Freeze Dry, Inc.
Figure 9.23 A programmable batch-type freeze-dryer. Courtesy of Ilshin Lab.
Figure 9.24 A continuous-type freeze-dryer. Courtesy of Oregon Freeze Dry, Inc.
Chapter 10: Environmental Impact and Sustainability Assessment of Refrigeration Systems
Figure 10.1 Major environmental concerns.
Figure 10.2 Anthropogenic environmental impact on the atmosphere and global climate change.
Figure 10.3 Dincer's six pillars of critical targets to achieve better sustainability.
Figure 10.4 Dincer's 3S concept, covering the entire spectrum from source to service provided.
Figure 10.5 Greenization for refrigeration systems from non-green to green.
Figure 10.6 Four categories of sustainable development.
Figure 10.7 Energy and exergy analyses as potential tools in achieving sustainability.
Figure 10.8 Qualitative illustration of the relation between the environmental impact and sustainability of a refrigeration process and its exergetic COP.
Figure 10.9 Summary of the energy sources considered for VCRSs and ARSs in the case study.
Figure 10.10 Annual electricity generation rates of the VCRS energy sources.
Figure 10.11 Capacity factors of the VCRS energy sources.
Figure 10.12 Average energy requirements (kW
th
/kW
el
) of the VCRS energy sources.
Figure 10.13 Average electricity production costs of the VCRS energy sources.
Figure 10.14 Average carbon dioxide emissions of the VCRS energy sources.
Figure 10.15 Average rankings of geothermal, large-scale hydro, wind, small-scale hydro, and coal energy sources for VCRS.
Figure 10.16 Average typical heat generation sizes of the ARS energy sources.
Figure 10.17 Capacity factors of the ARS energy sources.
Figure 10.18 Average investment costs of the ARS energy sources.
Figure 10.19 Average design lifetimes of the ARS energy sources.
Figure 10.20 Average carbon dioxide emissions of the ARS energy sources.
Figure 10.21 Average rankings of geothermal, ocean, biomass, gas, and CSP for ARS.
List of Tables
Chapter 1: General Aspects of Thermodynamics
Table 1.1 Some of most common thermocouples
Table 1.2 Equations for gas and gas mixtures and relevant models
Chapter 2: Refrigerants
Table 2.1 The prefixes and atoms in refrigerants
Table 2.2 ODPs, GWPs, and CAS numbers of Class I and II ODSs
Table 2.3 AccepTable substitutes for commercial refrigeration under the SNAP program
Table 2.4 AccepTable substitutes for noncommercial refrigeration under SNAP the program
Table 2.5 Some common zeotropic mixtures in the 400 series
Table 2.6 Some common azeotropic mixtures in the 500 series
Table 2.7 Percentage compositions of substitute refrigerant blends
Table 2.8 Percentage compositions of substitutes for R-12
Table 2.10 Percentage compositions of substitutes for R-22
Table 2.11 Percentage compositions of substitutes for CFC-113, R-13B1, and R-503
Chapter 3: Refrigeration System Components
Table 3.1 Common types of compressors
Chapter 4: Refrigeration Cycles and Systems
Table 4.1 ARS data obtained from the analysis
Chapter 6: Renewable Energy-based Integrated Refrigeration Systems
Table 6.1 State point properties
Table 6.2 State point properties for the system given in Figure 6.7
Table 6.3 Parameters used in the case study
Chapter 7: Heat Pipes
Table 7.1 Some heat pipe fluids and their temperature ranges
Table 7.2 Heat pipe components and their effect on design requirements
Table 7.3 Heat pipe heat transport limitations
Chapter 8: Food Refrigeration
Table 8.1 Common food preservation methods
Table 8.2 Advantages and disadvantages of vacuum cooling for some food commodities
Table 8.3 Recommended precooling methods for fruits and vegetables
Table 8.4 Comparison of quick freezing and slow freezing
Table 8.5 Typical insulation thickness for cool and cold stores utilizing different insulation materials
Table 8.6 Typical storage life of some fruits and vegeTable in CAS with the PRISM Alpha System
Table 8.7 Comparison of storage life in air and CAS
Table 8.8 Comparison of the storage lives of some products subject to CAS/MAP and ordinary air cooling storage
Table 8.9 Maximum heat generation values of some products
Table 8.10 Constants for heat generation of fruits and vegeTable in the range of 0 °C to 20 °C, based on Equation 8.3
Table 8.11 Transpiration coefficients of some fruits and vegetables
Table 8.12 Experimental cooling process data for the individual products
Table 8.13 Geometric parameters used in the modeling for various shapes
Table 8.14 Some common specific heat correlations
Table 8.15 Some common specific heat correlations with solids, proteins, fats, and carbohydrates
Table 8.16 Specific heat of some food products
Table 8.17 Some common thermal conductivity correlations
Table 8.18 Some common thermal conductivity correlations for liquid and solid food products, with solids, proteins, fats, and carbohydrates
Table 8.19 Experimental thermal conductivities of some food products at 23 °C
Table 8.20 Thermal diffusivity values of some food products
Table 8.21 The values of μ
1
,
A
1
,
G
, and Bi for the ISP, ICP and SP
Table 8.22 Cooling experimental heat-transfer data and model results.
Table 8.23 The values of
U
,
C
,
h,
Nu, and Di for some products (
k
f
= 0.0239 W/m °C).
Chapter 9: Food Freezing
Table 9.1 Freezing temperatures of various foods
Table 9.2 The quality parameters of the samples.
Table 9.3 Freezing rates of some fruits and vegetables
Table 9.4 Experimental freezing points of some fruits and vegetables
Table 9.5 Comparison of two types of contact freeze-dryers
Chapter 10: Environmental Impact and Sustainability Assessment of Refrigeration Systems
Table 10.1 Atmospheric pollutants released by power generation systems
Table 10.2 The principal greenhouse gases and their approximated concentration in the atmosphere
Table 10.3 Categories and kinds of indicators influencing sustainability assessment
Table 10.4 Brief comparison of ARS- and VCRS-based refrigeration processes
Table 10.5 Energy sources and performance criteria used to evaluate ARS- and VCRS-based refrigeration processes
Table 10.6 Annual electricity generation rates of selected sources considered for VCRSs and their normalized ranking data
Table 10.7 Capacity factors of selected sources considered for VCRSs and their normalized ranking data
Table 10.8 Energy requirements of selected sources considered for VCRSs and their normalized ranking data
Table 10.9 Electricity production costs of selected sources considered for VCRSs and their normalized ranking data
Table 10.10 CO
2
emissions of selected sources considered for VCRSs and their normalized ranking data
Table 10.11 Normalized rankings of selected sources considered for VCRSs and their average normalized ranking
Table 10.12 Typical heat generation sizes of selected sources considered for ARSs and their normalized ranking data
Table 10.13 Capacity factors of selected sources considered for ARSs and their normalized ranking data
Table 10.14 Investment costs of selected sources considered for ARSs and their normalized ranking data
Table 10.15 Design lifetimes of heat production from selected sources considered for ARSs and their normalized ranking data
Table 10.16 CO
2
emissions of selected sources considered for ARSs and their normalized ranking data
Table 10.17 Normalized rankings of selected sources considered for ARSs and their average normalized ranking
Refrigeration Systems and Applications
Third Edition
Ibrahim Dincer
University of Ontario Institute of Technology, Canada
This edition first published 2017
© 2017 John Wiley & Sons Ltd
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Library of Congress Cataloging-in-Publication Data
Names: Dincer, Ibrahim, 1964-
Title: Refrigeration systems and applications / Ibrahim Dincer, University of Ontario, Ontario, Canada.
Description: Thrid edition. | Chichester, West Sussex, UK : John Wiley & Sons, Inc., 2017. | Includes bibliographical references and index.
Identifiers: LCCN 2016046162 (print) | LCCN 2016049869 (ebook) | ISBN 9781119230755 (cloth) | ISBN 9781119230762 (pdf) | ISBN 9781119230786 (epub)
Subjects: LCSH: Refrigeration and refrigerating machinery. | Thermodynamics.
Classification: LCC TP495 .D56 2017 (print) | LCC TP495 (ebook) | DDC 621.5/6-dc23
LC record available at https://lccn.loc.gov/2016046162
A catalogue record for this book is available from the British Library.
Cover image: © PM Images/Gettyimages; The diagram is courtesy of the author Cover design by Wiley
Preface
Refrigeration is a multidisciplinary area in which science and engineering meet to try to solve humankind's refrigeration needs in many sectoral applications, ranging from cooling of electronic devices to food cooling. It has a multidisciplinary character, involving a combination of several disciplines, including mechanical engineering, chemical engineering, chemistry, food engineering, civil engineering, and many more. The refrigeration industry was big in the past and has drastically expanded during the past two decades to play a significant role in societies and their economies. The economic impact of refrigeration technology throughout the world has therefore become more important and this will continue in the future due to the increasing demand for refrigeration systems and applications. This technology serves in countless ways to improve living conditions.
This third edition of the book has been improved and enhanced to cover the thermodynamic concepts in a better way, to include more materials and examples on energy and exergy analyses, energy and exergy efficiencies, and coefficients of performance, to include material on food refrigeration and food freezing applications, to add new and unique materials on renewable energy-based integrated refrigeration systems and the environmental impact and sustainability assessment of refrigeration systems, and to further clarify several sections. It is strongly believed that the book will be of interest to students, refrigeration engineers, practitioners, and producers, as well as people and institutions who are interested in refrigeration systems and applications. It is also a valuable and readable reference text and source for anyone who wishes to learn more about refrigeration and analysis.
The first chapter addresses general concepts, fundamental principles, and general aspects of thermodynamic concepts, analysis and performance assessment methods to furnish the reader with background information that is of relevance to the analysis of refrigeration systems and applications. Chapter 2 provides useful information on several types of refrigerants and their environmental impact, as well as their thermodynamic properties. Chapter 3 delves into the specifics of refrigeration system components and their operating and technical aspects, analysis details, utilization perspectives, etc. before examining refrigeration cycles and systems. Chapter 4 presents comprehensive coverage of basic refrigeration cycles and systems for various applications, along with energy and exergy analyses. Chapter 5 provides comprehensive material on advanced refrigeration cycles and systems along with non-conventional refrigeration systems for numerous applications with operational and technical details. There are illustrative examples on system analyses through energy and exergy methods which make this book unique. Chapter 6 covers the new topic of renewable energy sources for refrigeration applications, with various examples and a case study of an integrated renewable energy-based refrigeration system that generates both power and cooling. Chapter 7 is on heat pipes and their micro- and macro-scale applications, technical, design, manufacturing and operational aspects, heat pipe utilization in HVAC applications, and their performance evaluation. Chapter 8 presents comprehensive coverage of food preservation and its methods (physical, chemical, and biological), food quality, and energy use in food preservation technologies. This chapter deals with food refrigeration technology, particularly food preservation by refrigeration, food cooling systems and applications, cool and cold storage, transport refrigeration, respiratory heat generation, moisture loss in a broad perspective, effects of cooling on products, physical and microbiological changes, and detailed information on how to select cooling methods, specification, energy use processing conditions, and so forth. Additionally, the reader is provided with a practical historical and technological background of refrigeration and new applications in refrigeration, along with some practical examples. Cool and cold storage, controlled atmosphere storage, cold stores and their operation and maintenance, control and measuring devices for practical applications, machinery and system selection for cold stores, feasibility studies of cold stores, insulation practices, energy analysis and saving techniques, transport refrigeration, cooling load calculations for the systems and products, etc. are also discussed in detail. Chapter 9 provides useful information on various techniques and technical details for food freezing applications, freezing machinery, ice-making systems, and freeze-drying systems and applications, and their technical and economic evaluations as well as several methods for predicting freezing times of products. Chapter 10 discusses some critical aspects related to environmental impact and sustainable development, and linkages to refrigeration systems. Numerous topics, such as energy and environmental impact, and energy and sustainability as well as exergy and sustainability, are presented in addition to some tools such energy and exergy analyses for analysis, design, assessment, and improvement of refrigeration systems. Some further discussion is offered on system greenization, particularly for refrigeration systems and applications. A comprehensive case study is presented to provide a clear picture about the environmental impact and sustainability aspects of refrigeration systems.
Incorporated through this book are many wide-ranging examples which provide useful information for practical applications. Conversion factors and thermophysical properties of various materials, as well as a large number of food refrigeration data, are listed in the appendices in the International System of Units (SI). Complete references are included with each chapter to direct the curious and interested reader to further information.
Ibrahim DincerOshawa, 2016
Acknowledgments
I sincerely appreciate the assistance provided by Farrukh Khalid, Yusuf Bicer, Tahir Ratlamwala and Hadi Ganjehsarabi in preparing and making calculations for some examples and case studies. I also warmly thank Canan Acar, Maan Al-zareer, and Murat Demir for helping me in updating examples, figures, tables, etc.
Last but not least, I am deeply grateful to my wife Gulsen Dincer and my children Meliha, Miray, Ibrahim Eren, Zeynep, and Ibrahim Emir Dincer. They have been a great source of support and motivation, and their patience and understanding throughout this book have been most appreciated.
Ibrahim Dincer Oshawa, 2016
Chapter 1General Aspects of Thermodynamics
1.1 Introduction
Refrigeration has a diverse nature and covers a large number of processes ranging from cooling to air conditioning and from food refrigeration to human comfort. Refrigeration as a whole, therefore, appears complicated due to the fact that thermodynamics, fluid mechanics, and heat transfer are always encountered in every refrigeration process or application. For a good understanding of the operation of refrigeration systems and applications, an extensive knowledge of such topics is indispensable.
When an engineer or an engineering student undertakes the analysis of a refrigeration system and/or its application, he or she should deal with several basic aspects first, depending upon the type of the problem being studied, that may be of thermodynamics, fluid mechanics, or heat transfer. In conjunction with this, there is a need to introduce several definitions and concepts before moving into refrigeration systems and applications in depth. Furthermore, the units are of importance in the analysis of such systems and applications. One should make sure that the units used are consistent to reach the correct result. This means that there are several introductory factors to be taken into consideration to avoid getting lost further on. While the information in some situations is limited, it is desirable that the reader comprehend these processes. Despite assuming that the reader, if he or she is a student, has completed necessary courses in thermodynamics, fluid mechanics, and heat transfer, there is still a need for him or her to review, and for those who are practicing refrigeration engineers, the need is much stronger to understand the physical phenomena and practical aspects, along with a knowledge of the basic laws, principles, governing equations, and related boundary conditions. In addition, this introductory chapter reviews the essentials of such principles, laws, etc., discusses the relationships between the aspects and provides some key examples for better understanding.
This chapter primarily focuses on general aspects of thermodynamics, ranging from dimensions and units to psychrometric processes, and specifically discusses systems of units, thermodynamic systems, thermodynamic laws, pure substances, ideal and real gases, refrigerators and heat pumps, Carmot cycles, and psychrometrics and its processes. We also introduce performance assessment criteria through energy and exergy efficiencies and energetic and exergetic coefficients of performance (COPs) by the thermodynamic laws. The chapter presents lots of examples to show how to utilize thermodynamic tools, particularly balance equations, for design, analysis, and assessment.
1.2 Dimensions and Units
In the area of refrigeration it is critical to employ dimensions and units correctly for analysis, design, and assessment. It is commonly accepted that any physical quantity can be characterized by dimensions. Their magnitudes are measured/recognized in units. There are numerous commonly accepted dimensions, namely mass (m), length (L), time (t), and temperature (T), which are treated as primary quantities. There are also several other quantities, such as force (F), pressure (P), velocity (V), energy (E), and exergy (Ex), which are treated as the derived dimensions. We discuss several of these in the following subsections.
1.2.1 Systems of Units
Units are accepted as the currency of science. There are two systems: the International System of Units (Le Système International d'Unitès), which is always referred to as SI units, and the English System of Units (the English Engineering System). SI units are the most widely used throughout the world, although the English System is utilized as the traditional system of North America. In this book, SI units are primarily employed. Appendix A contains some common conversions. The dimensions, such as mass, length, force, density, specific volume, mass flow rate, volumetric flow rate, temperature and pressure, are briefly described below.
1.2.1.1 Mass
Mass is defined as a quantity of matter forming a body of indefinite shape and size. The fundamental unit of mass is the kilogram (kg) in SI and its unit in the English System is the pound mass (lbm). The basic unit of time for both unit systems is the second (s). The following relationships exist between the two unit systems:
In thermodynamics the unit mole (mol) is commonly used and defined as a certain amount of substance containing all the components. The related equation is defined as
where if m and M are given in grams and gram/mol, we get n in mol. If the units are kilogram and kilogram/kilomol, n is in kilomol (kmol). For example, one mol of water, having a molecular weight of 18 (compared to 12 for carbon-12), has a mass of 0.018 kg and for one kmol it becomes 18 kg.
1.2.1.2 Length
The basic unit of length is the meter (m) in SI and the foot (ft) in the English System, which additionally includes the inch (in) in the English System and the centimeter (cm) in SI. Here are some interrelations:
1.2.1.3 Force
A force is a kind of action that brings a body to rest or changes the direction of motion (e.g., a push or a pull). The fundamental unit of force is the Newton (N):
The four aspects, that is, mass, time, length and force, are interrelated by Newton's second law of motion, which states that the force acting on a body is proportional to the mass and acceleration in the direction of the force, as given below:
Equation (1.2) shows the force required to accelerate a mass of one kilogram at a rate of one meter per square second as 1 N = 1 kg m/s2.
It is important to note the value of the earth's gravitational acceleration as 9.80665 m/s2 (generally taken as 9.81 m/s2) in the SI system and 32.174 ft/s2 in the English System, which indicates that a body falling freely toward the surface of the earth is subject to the action of gravity alone. Some common conversion factors are listed in Appendix in A.
1.2.1.4 Density and Specific Volume
Specific volume is defined as the volume per unit mass of a substance, usually expressed in cubic meters per kilogram (m3/kg) in the SI system and in cubic feet per pound (ft3/lb) in the English System. The density of a substance is defined as the mass per unit volume, and is therefore the inverse of the specific volume:
Its units are kg/m3 in the SI system and lbm/ft3 in the English System. Specific volume is also defined as the volume per unit mass, and density as the mass per unit volume, that is,
Both specific volume and density are intensive properties and affected by temperature and pressure. The related interconversions are
1.2.1.5 Mass Flow Rate and Volumetric Flow Rate
Mass flow rate is defined as the mass flowing per unit time (kg/s in the SI system and lb/s in the English System). Volumetric flow rates are given in m3/s in the SI system and ft3/s in the English System. The following expressions can be written for the flow rates in terms of mass, specific volume, and density:
1.2.1.6 Temperature
Temperature is an indication of the thermal energy stored in a substance. In other words, we can identify hotness and coldness with the concept of temperature. The temperature of a substance may be expressed in either relative or absolute units. The two most common temperature scales are Celsius (°C) and Fahrenheit (°F). Normally, the Celsius scale is used with the SI unit system and the Fahrenheit scale with the English System. There are also two more scales, the Kelvin scale (K) and the Rankine scale (R), which are sometimes employed in thermodynamic applications. The relations between these scales are summarized as follows:
Furthermore, the temperature differences result in
Here, Kelvin is a unit of temperature measurement: zero Kelvin (0 K) is the absolute zero and is equal to −273.15 °C. Both K and °C are equal increments of temperature. For instance, when the temperature of a product is decreased to −273.15 °C (or 0 K), known as absolute zero, the substance contains no heat energy and supposedly all molecular movement stops. The saturation temperature is the temperature of a liquid or vapor at saturation conditions.
Temperature can be measured in many ways by many devices. In general, the following devices are in common use:
Liquid-in-glass thermometers
. It is known that in these thermometers the volume of the fluid expands when subjected to heat, thereby raising its temperature. It is important to note that in practice all thermometers, including mercury ones, only work over a certain range of temperature. For example, mercury becomes solid at −38.8 °C and its properties change dramatically.
Resistance thermometers
. A resistance thermometer (or detector) is made of resistance wire wound on a suitable former. The wire used has to be of known, repeatable, electrical characteristics so that the relationship between the temperature and resistance value can be predicted precisely. The measured value of the resistance of the detector can then be used to determine the value of an unknown temperature. Amongst metallic conductors, pure metals exhibit the greatest change of resistance with temperature. For applications requiring higher accuracy, especially where the temperature measurement is between −200 °C and +800 °C, the majority of such thermometers are made of platinum. In industry, in addition to platinum, nickel (−60 °C to +180 °C) and copper (−30 °C to +220 °C) are frequently used to manufacture resistance thermometers. Resistance thermometers can be provided with two, three, or four wire connections and for higher accuracy at least three wires are required.
Averaging thermometers
. An
