Giovanni Petrecca
Energy
Conversion and Management
Principles and Applications
Energy Conversion and Management
Giovanni Petrecca
Energy Conversion and Management
Principles and Applications
Giovanni Petrecca
Department of Industrial Engineering University of Pavia
Pavia, Italy
ISBN 978-3-319-06559-5 ISBN 978-3-319-06560-1 (eBook) DOI 10.1007/978-3-319-06560-1
Springer Cham Heidelberg New York Dordrecht London
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After many years of researching, teaching, and consulting I am firmly convinced that all problems, in order to be solved, must first be reduced to their essentials.
That does not mean ignoring or skating over some aspects, but on the contrary it means going deeply into the core of the problem to understand it completely, and then focusing on the few elements really necessary for its solution.
This is quite a difficult approach because it requires a clear comprehension of what is really important and of what is not. Engineering universities generally train students to achieve that, but during the professional career a great effort must always be made to apply these principles to practical problems.
I became engaged in the research for a unifying approach to energy management after experiences in teaching electrical machines and drives with the unified theory, which in 1976 was rather innovative for the student curriculum, but was afterwards demonstrated to be an excellent approach to an intimate and all-embracing com- prehension of the related phenomena.
Professional experiences in the field of industrial energy conversion and man- agement had stimulated me to organize a course on this subject in the Engineering Faculty of the University of Pavia in Italy and, in 1992, to write a text providing a global view of energy management in industry and in buildings.
The stream of energy, in different forms, which is transformed step by step inside any factory and building, has been considered as the unifying factor for understanding all the topics, which at first glance seem to be comprehensible only in terms of independent theories.
After 20 years I have decided to write a new book that still keeps the original approach, but which also includes the innovations that have influenced this period.
In conclusion, this new book is not just another specialized textbook or hand- book and so it does not compete with those already existing which remain indis- pensable tools for solving technical problems in detail. Rather, it aims to help the reader by giving them the fundamental elements to simplify and tackle problems within a global vision of the production units by exploiting the correlations always present among many topics apparently distant from one another.
Having completed this work, I should like to thank university and professional colleagues who made suggestions to facilitate the comprehension of many topics.
In addition, thanks are due to CSE Srl, Pavia, Italy (founded in 1983, it now belongs
vii
to EDISON Group, Italy), from whose data bank most of the examples have been drawn.
Many thanks to all the students whom I have encountered over the years, as I have come to appreciate that teaching is the best way to deeply understand the subject you are talking about.
On a more personal note, I should like to thank my wife Marina, who helped me see the book through non-technical eyes.
Pavia, Italy Giovanni Petrecca
February 2014
viii Preface
1 Introduction. . . 1
1.1 General Principles of Energy Conversion and Management . . . 1
1.2 Energy Transformations in Factories and Buildings . . . 3
1.3 The Plan of the Book . . . 4
2 Power and Energy Measurement Units and Techniques. . . 7
2.1 The SI System and Conversion Factors . . . 7
2.2 Primary Energy Measurement Units . . . 8
2.3 End User Energy Measurement Units . . . 14
2.4 An Outline of the Main Measurement Techniques . . . 15
2.4.1 Liquid and Gas Measurements . . . 15
2.4.2 Electric Energy Flow Measurements . . . 20
2.4.3 Temperature, Pressure, and Other Measurements . . . 23
3 World Energy Demand. . . 25
3.1 Introduction . . . 25
3.2 World Energy Demand and Population . . . 25
3.3 Energy End Users . . . 27
3.3.1 Industry . . . 27
3.3.2 Transport . . . 28
3.3.3 Residential and Non-Residential Buildings . . . 28
3.3.4 Agriculture . . . 28
3.3.5 Energy Industry . . . 28
3.3.6 Non-energy Uses . . . 28
3.4 An Outline of Industrial Energy Consumption . . . 28
4 Utility Plants and Renewable Sources. . . 31
4.1 Introduction . . . 31
4.2 Utility Plants and Renewable Sources, from Input Energy to End Users . . . 31
ix
4.3 Renewable Sources: Solar Energy . . . 32
4.3.1 Hot Water from Solar Energy . . . 32
4.3.2 Photovoltaic Systems . . . 33
4.3.3 Solar Concentrated Solar Power Systems . . . 33
4.4 Renewable Sources: Wind Energy . . . 34
4.5 Renewable Sources: Geothermal Energy . . . 35
4.6 Renewable Sources: Wave, Tidal, and Ocean Thermal Energy . . . 36
4.7 Renewable Sources: Hydraulic Energy . . . 37
4.8 Renewable Sources: Energy from Waste . . . 40
4.9 Energy Storage: Hydro, Mechanical, Electric, Fuel Cell, Thermal Storage . . . 40
4.9.1 Hydro Storage . . . 42
4.9.2 Mechanical Storage . . . 42
4.9.3 Electric Storage . . . 43
4.9.4 Fuel Cells . . . 44
4.9.5 Heat and Cold Storage . . . 46
4.10 Applicability in Factories and in Buildings . . . 48
5 Electrical Substations. . . 49
5.1 Introduction . . . 49
5.2 Basic Principles of Transformer Losses and Efficiency . . . 49
5.3 How to Choose the Most Suitable Transformer . . . 51
5.4 Practical Examples . . . 54
6 Boiler Plants. . . 57
6.1 Introduction . . . 57
6.2 Basic Principles of Combustion . . . 58
6.3 Combustion Efficiency . . . 61
6.4 Fundamentals of Steam Generation . . . 62
6.5 Industrial Boilers . . . 64
6.5.1 Steam Watertube Boilers . . . 68
6.5.2 Steam Firetube Boilers . . . 70
6.5.3 Heat Recovery Boilers . . . 70
6.5.4 Electric/Electrode Boilers . . . 71
6.5.5 Oil Boilers . . . 72
6.6 Technical Parameters of Industrial Steam Boilers . . . 72
6.7 Boiler Losses and Efficiency . . . 73
6.7.1 Input–Output Method . . . 74
6.7.2 Heat-Loss Method . . . 74
6.8 How to Improve Boiler Efficiency . . . 81
6.9 Auxiliary Equipment . . . 84
6.9.1 Heat-Recovery Systems . . . 84
6.9.2 Water Treatment Systems . . . 85
6.9.3 Condensate Return Systems . . . 86
x Contents
6.10 Computerized Control of Boiler Combustion . . . 88
6.11 Boiler Emission and Environmental Pollution . . . 89
6.11.1 Sulfur Dioxide . . . 89
6.11.2 Nitrogen Oxides . . . 90
6.11.3 Carbon Monoxide . . . 91
6.11.4 Particulate Matter . . . 92
6.11.5 Hydrocarbons . . . 92
6.11.6 Other Pollutants . . . 92
6.11.7 Carbon Dioxide and Greenhouse Gases . . . 93
6.12 Practical Examples . . . 93
7 Electric Distribution Systems from Facilities to End Users. . . 97
7.1 Introduction . . . 97
7.2 Electric Distribution Losses . . . 99
7.3 Power Factor Control . . . 102
7.4 Electrical Drives . . . 105
7.4.1 Basic Principles and Operating Modes of Electrical Machines . . . 107
7.4.2 Basic Principles and Operating Modes of Electrical Drives . . . 109
7.4.3 Application Problems . . . 111
7.5 Electrically Heated End Users . . . 111
7.5.1 Joule Losses Principle . . . 112
7.5.2 Electromagnetic Wave Heating . . . 112
7.5.3 Heat Pumps . . . 113
7.5.4 Mechanical Recompression and Thermocompression of Steam . . . 113
7.6 End Users and Load Management . . . 116
7.7 Practical Examples . . . 117
8 Thermal Fluid Distribution Systems. . . 125
8.1 Introduction . . . 125
8.2 Components of Steam and Other Fluid Systems . . . 125
8.3 Basic Principles of Pipeline Losses and Insulation . . . 127
8.3.1 Flat-Surface Multilayer System (See Fig. 8.2) . . . 131
8.3.2 Cylindrical Surface Multilayer System (See Fig. 8.3) . . . 134
8.3.3 Tanks, Other Equipment . . . 137
8.4 Thermal Energy End Users . . . 137
8.4.1 Heating a Mass by Steam . . . 138
8.4.2 Exchanging Heat Between a Fluid and Steam (See Also Chap. 15) . . . 138
8.4.3 Extraction of Water in Industrial Dryers by Evaporation . . . 138
8.5 Practical Examples . . . 138
9 Cogeneration Plants. . . 141
9.1 Introduction . . . 141
9.2 Forms of Cogeneration and Trigeneration . . . 142
9.3 The Backpressure or Non-condensing Steam Turbine . . . 144
9.4 The Gas Turbine . . . 150
9.5 The Reciprocating Engine . . . 153
9.6 Determining the Feasibility of Cogeneration . . . 155
9.7 Practical Examples . . . 157
10 Facilities: Pumps and Fans. . . 163
10.1 Introduction . . . 163
10.2 Basic Principles of Pump and Fan Operation . . . 165
10.3 Methods of Regulating the Working Point . . . 170
10.3.1 Dissipative Methods for Pumps and Fans . . . 170
10.3.2 Non-dissipative Methods for Pumps and Fans . . . 171
10.4 Comparison Between Dissipative and Non-dissipative Regulation Methods . . . 173
10.5 Pump and Fan Regulation Methods . . . 175
10.6 Practical Examples . . . 175
11 Facilities: Gas Compressors. . . 179
11.1 Introduction . . . 179
11.2 Basic Principles of Compressed-Air Systems . . . 180
11.2.1 Isothermal Compression . . . 180
11.2.2 Adiabatic Compression . . . 180
11.2.3 Polytrophic Compression . . . 182
11.3 Auxiliary Equipment . . . 186
11.4 Technical Data on Industrial Air Compressors and Control Systems . . . 187
11.5 The Control of Air Compressors . . . 190
11.6 Compressed-Air Systems: Distribution Lines and End Users . . . 191
11.6.1 The Distribution Lines . . . 191
11.6.2 The End Users . . . 192
11.7 Energy-Saving Investments . . . 195
11.8 Practical Examples . . . 195
12 Facilities: Cooling Systems. . . 199
12.1 Introduction . . . 199
12.2 Basic Principles of Vapor-Compression Systems . . . 199
12.2.1 Vaporization (Process from 4 to 10or 1) . . . 201
12.2.2 Compression (Process from 1 to 2s or to 2) . . . 202
12.2.3 Condensation (Process from 2 to 30or 3) . . . 203
12.2.4 Expansion (Process from 30or 3 to 4) . . . 203
12.2.5 Practical Vapor-Compressor Cycles . . . 205
xii Contents
12.3 Coolant Properties and Applications . . . 205
12.4 The Main Components of Vapor-Compression Systems . . . 207
12.4.1 Evaporator . . . 207
12.4.2 Compressor . . . 207
12.4.3 Condenser . . . 208
12.4.4 Expansion Valve . . . 210
12.5 Cascade and Multistage Systems . . . 210
12.6 Absorption Refrigerating Systems . . . 210
12.7 Brayton Refrigeration Cycle . . . 213
12.8 Energy Saving and Computer Control . . . 214
12.9 Heat Pump Operation . . . 215
12.10 Practical Examples . . . 216
13 Facilities-HVAC Systems. . . 221
13.1 Introduction . . . 221
13.2 Basic Principles of HVAC Systems . . . 222
13.2.1 Typical Air Conditioning Processes . . . 227
13.3 Heating and Cooling Load Calculation . . . 229
13.4 Typical HVAC Systems . . . 231
13.4.1 All-Air Systems . . . 232
13.4.2 All-Water Systems . . . 233
13.4.3 Air-Water Systems . . . 233
13.4.4 Individual Units . . . 233
13.4.5 Radiant Systems for Heating . . . 233
13.5 Centralized Control . . . 234
13.6 Energy-Saving Systems . . . 234
13.7 Practical Examples . . . 235
14 Facilities: Lighting. . . 241
14.1 Introduction . . . 241
14.2 Basic Principles of Lighting Systems and Definitions . . . 241
14.3 Typical Lighting Systems and Related Equipment . . . 242
14.3.1 Incandescent Lamps . . . 244
14.3.2 Fluorescent Lamps . . . 246
14.3.3 High-Intensity Discharge Lamps . . . 246
14.3.4 Light-Emitting Diode Lamps . . . 247
14.3.5 Luminaires . . . 247
14.3.6 Lighting Control . . . 248
14.4 How to Choose a Lighting System . . . 249
14.5 Energy-Saving Opportunities . . . 250
14.6 Practical Examples . . . 250
15 Heat Exchange and Recovery in Process and Facilities. . . 255
15.1 Introduction . . . 255
15.2 Opportunities for Heat Recovery from Process and Facility Plants . . . 255
15.3 Heat Exchange and Recovery Systems . . . 257
15.4 Basic Principles of Heat Exchanger Operation . . . 257
15.5 Preliminary Evaluation Criteria for Heat Exchangers . . . 264
15.5.1 The Log-Mean Temperature Method . . . 264
15.5.2 Effectiveness-NTU Method . . . 265
15.6 A Classification of Heat Exchangers and Their Selection Criteria . . . 267
15.6.1 Shell and Tube Heat Exchanger . . . 267
15.6.2 Double-Pipe Heat Exchanger . . . 267
15.6.3 Gasketed-Plate Heat Exchanger . . . 267
15.6.4 Welded-Plate Exchanger . . . 268
15.6.5 Hot-Gas-to-Liquid Convective Bank System . . . 268
15.6.6 Gas-to-Gas Recuperative Heat Exchanger . . . 268
15.6.7 Heat Pipe Exchanger . . . 268
15.6.8 Rotary Regenerator . . . 269
15.7 Practical Examples . . . 269
16 Waste and Energy Recovery. . . 273
16.1 Introduction . . . 273
16.2 Waste Management . . . 274
16.3 Energy Recovery from Waste . . . 276
16.4 Waste and Energy Management Functions in Industry . . . 277
17 Energy Management Strategies for Control and Planning. . . 279
17.1 Introduction . . . 279
17.2 The Different Steps of an Energy Management Approach . . . 280
17.3 Preliminary Technical and Economic Evaluation of Energy-Saving Investments . . . 291
17.4 Off-Line and On-Line Procedures for Energy Accounting . . . 291
17.5 Feasibility Studies and Financing . . . 292
17.6 Personnel Training . . . 293
17.7 A Successful Energy Management Program . . . 293
17.8 Centralized Control of Process and Facility Plants . . . 294
17.9 Practical Examples . . . 296
18 Education in Energy Conversion and Management. . . 297
18.1 Introduction . . . 297
18.2 The Role of University . . . 297
18.3 Personnel Training . . . 298
18.4 Awareness of Energy Conversion and Management as an Intersectoral Discipline . . . 299
19 Economic Analysis of Energy-Saving Investments. . . 301
19.1 Introduction . . . 301
19.2 Methods Not Using Life Cycle Costing . . . 301
19.2.1 Payback Method . . . 301
19.2.2 Investors’ Rate of Return (ROR) Method . . . 302
xiv Contents
19.3 Methods Using Life Cycle Costing . . . 302
19.3.1 Present Worth Method . . . 303
19.3.2 Internal Rate of Return (IRR) . . . 305
19.4 Case Studies . . . 305
20 Conclusions. . . 311
References. . . 315
Index. . . 317
Fig. 1.1 Energy flow through the site boundary . . . 3 Fig. 2.1 Velocity meter with a turbine rotor . . . 16 Fig. 2.2 Different types of head meters. (a) Thin plate orifice;
(b) sharp edge orifice; (c) Venturi tube. Upstream (p1)
and downstream (p2) . . . 17 Fig. 2.3 Pitot tube . . . 18 Fig. 2.4 Vortex meter . . . 19 Fig. 2.5 Typical connection schemes: voltmeter, ammeter
and wattmeter with single-phase line (a) and with three-phase line (b) . . . 22 Fig. 2.6 Relationships among the Kelvin (K), Celsius (C),
Rankine (R) and Fahrenheit (F) temperatures . . . 24 Fig. 2.7 Relationships among the absolute, atmospheric, gage
and vacuum pressures . . . 24 Fig. 3.1 Gross and final consumption in a typical industrialized country
with a gross consumption of 160 MTOE and a population
of 50 million people . . . 27 Fig. 4.1 Range of typical variations for annual average wind velocity–
duration curves (each wind velocity point on the curve corresponds to the number of hours during which this velocity has been exceeded) . . . 35 Fig. 4.2 Ranges of application of various types of hydraulic turbine
units (100–3,000 kW) . . . 39 Fig. 4.3 Effect of load on the efficiency of hydraulic turbines . . . 40 Fig. 4.4 Possible ways of converting waste into energy . . . 41 Fig. 5.1 Transformer efficiency versus load factorxfor a group
of transformers with the same rated power and rated total
losses, but with different values ofrratio . . . 51 Fig. 5.2 Ratiorversus load factorxif the maximum transformer
efficiency condition is imposed . . . 52 Fig. 5.3 Operating parameters for a standard 1,000 kVA transformer,
as specified in Table 5.2 . . . 54 xvii
Fig. 6.1 Enthalpy entropy diagram for water
(Mollier diagram—SI units) . . . 64
Fig. 6.2 Enthalpy entropy diagram for water (Mollier diagram— English units) . . . 65
Fig. 6.3 Watertube boiler basic circuit . . . 68
Fig. 6.4 Basic and auxiliary equipment for a watertube boiler . . . 69
Fig. 6.5 Firetube boiler basic circuit . . . 70
Fig. 6.6 Example of radiation losses chart (each curve corresponds to a boiler rated power value) . . . 75
Fig. 6.7 Typical relationship between stack gas concentrations of CO2(%) and O2(%) and excess air (%) . . . 77
Fig. 6.8 Stack gas losses (natural gas) . . . 78
Fig. 6.9 Unburned CO losses versus O2concentration by volume for different values of CO emissions for natural gas (CO losses are here referred only to the Higher Heating Value; CO concentration equal to 100 ppm or 0.01 % in volume corresponds to 125 mg/Sm3) . . . 79
Fig. 6.10 Ostwald triangle for natural gase%¼VVVthth100; concentration by volume (dry) . . . 80
Fig. 6.11 Ranges of boiler operating efficiencies . . . 81
Fig. 6.12 Variation in boiler efficiency losses with changes in boiler firing rate with natural gas in two operating conditions (O2% is kept constant to roughly 3 % in volume—see Table 6.8—over the load range by means of combustion control; O2% increases linearly as load is reduced if combustion control is not installed) . . . 84
Fig. 6.13 Flash steam recovery in spray tank . . . 88
Fig. 7.1 Industrial electric distribution systems: Radial, loop feeder . . . . 98
Fig. 7.2 Current density of different copper cables: (a) Single-core paper insulated in air; (a0) single-core paper insulated under- ground; (b) three-core paper insulated in air; (b0) three-core paper insulated underground; (c) non-insulated conductor in air; (d) single-core rubber insulated cables . . . 101
Fig. 7.3 Power factor control: A basic scheme of installation . . . 104
Fig. 7.4 Basic scheme of electrical drives . . . 105
Fig. 7.5 Efficiency versus output power for electric motors . . . 106
Fig. 7.6 Torque-speed characteristics for electrical machines at given input voltage and current . . . 108
Fig. 7.7 Constant-torque and constant-power region for drives with synchronous (a), asynchronous (b), and d.c. machines (c) . . . 110
Fig. 7.8 Operating principles of MVR (mechanical vapor recompression) and TVR (thermal vapor recompression) . . . 115
Fig. 7.9 Typical values of overall efficiency from site boundaries to electric equipment terminals . . . 116
Fig. 7.10 Simplified equivalent circuit for a distribution line . . . 117
xviii List of Figures
Fig. 7.11 An example of an industrial electric distribution line;
see Table 7.2 for calculation . . . 118
Fig. 7.12 An example of an industrial electric distribution line; see Table 7.3 for calculation . . . 119
Fig. 8.1 Typical steam system circuit . . . 126
Fig. 8.2 Heat transfer through a multilayer wall . . . 132
Fig. 8.3 Heat transfer through a multilayer pipe . . . 134
Fig. 9.1 Basic scheme of a cogeneration plant . . . 143
Fig. 9.2 Basic scheme of a trigeneration plant . . . 144
Fig. 9.3 Theoretical steam rate and available energy representation by the Mollier diagram . . . 145
Fig. 9.4 Steam turbine types for cogeneration systems: (a) straight non-condensing (b) single extraction non-condensing (c) double extraction condensing . . . 147
Fig. 9.5 Plant combined cycle cogeneration steam system . . . 148
Fig. 9.6 Simple gas turbine: (a) open to the atmosphere; (b) closed . . . 150
Fig. 9.7 Cogeneration plant with backpressure steam turbine . . . 158
Fig. 9.8 Cogeneration plant with gas turbine . . . 159
Fig. 9.9 Cogeneration plant with reciprocating engine . . . 160
Fig. 9.10 Trigeneration plant with reciprocating engine . . . 161
Fig. 10.1 Characteristic curves for different classes of volumetric machines . . . 164
Fig. 10.2 Basic types of rotating pumps, fans, and compressors: (a) axial flow, (b) centrifugal, (c) lobe (intermittent flow) . . . 164
Fig. 10.3 Pump and load characteristics . . . 166
Fig. 10.4 Set of curves for a given pump . . . 167
Fig. 10.5 Pump flow rate and total head versus speed . . . 168
Fig. 10.6 Typical load circuits: (a) Dynamic losses lower than static losses; (b) dynamic losses greater than static losses . . . 169
Fig. 10.7 Pump and load curves corresponding to the circuits in Fig. 10.6 . . . 171
Fig. 10.8 Pump curves at different shaft speeds . . . 172
Fig. 10.9 Working points with dissipative and non-dissipative regulation (see the example in Sect. 10.6) . . . 173
Fig. 10.10 Characteristic pump curves for a given pump at fixed speed (see the example in Sect. 10.6) . . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. . 174
Fig. 11.1 Pressure-specific volume curves for various gas compression processes . . . 181
Fig. 11.2 Energy balance in a controlled-volume system . . . 183
Fig. 11.3 Energy flow from input section to mechanical energy end user section in a compressed-air system . . . 194
Fig. 12.1 A vapor-compression refrigeration system . . . 200
Fig. 12.2 Diagrams of vapor-compression refrigeration cycle: (a) Temperature-entropy diagram, (b) pressure-enthalpy diagram . . . 201
Fig. 12.3 Reverse Carnot vapor refrigeration cycle . . . 204
Fig. 12.4 Example of a cascade vapor-compression refrigeration cycle . . . 211
Fig. 12.5 An absorption refrigeration system . . . 212
Fig. 12.6 Basic scheme of a Brayton refrigeration cycle . . . 217
Fig. 12.7 Theoretical COP versus load temperatures for heat pumps . . . 216
Fig. 12.8 Example of air-to-air reversing heat pump . . . 217
Fig. 13.1 Typical water vapor states in an air-water mixture . . . 223
Fig. 13.2 Adiabatic saturator: Basic equipment andT–vdiagram representation . . . 225
Fig. 13.3 An example of a psychrometric chart as suggested by ASHRAE . . . 227
Fig. 13.4 Dehumidification by a cooling section followed by a re-heating section: Basic equipment and psychrometric chart representation . . . 228
Fig. 13.5 A basic scheme of air-handling unit . . . 232
Fig. 13.6 Flow of the air without and with recovery equipment in the cold season . . . 236
Fig. 13.7 Flow of the air without and with recovery equipment in the hot season . . . 236
Fig. 14.1 Example of curves of the depreciation factor (ratio between the illumination provided at various points in time and that provided by the new system; it is expressed as a percentage) . . . 243
Fig. 14.2 Example of distribution diagram . . . 248
Fig. 15.1 Temperature profiles for different types of exchangers . . . 259
Fig. 15.2 Basic arrangements of different types of exchangers . . . 259
Fig. 15.3 Correction factor FT for a crossflow exchanger (PandR parameters are calculated on the assumption that the cold and hot fluids have the same heat capacity) . . . 262
Fig. 15.4 Effectiveness versus NTU factor for a parallel flow exchanger . . . 266
Fig. 15.5 Effectiveness versus NTU factor for a counterflow exchanger . . . 266
Fig. 15.6 Air exhaust gas crossflow exchanger. Operating data as for Example 2 . . . 271
Fig. 17.1 A suggested basic approach to energy management: the program can be started at different levels . . . 280
Fig. 17.2 A basic scheme for energy and waste management by computerized systems on site and interaction with external networks and utility plants . . . 294
Fig. 18.1 Integration between energy conversion and management topics and specialized courses (shaded areasevidence integration) . . . 300
xx List of Figures
Table 2.1 SI base and supplementary units . . . 8 Table 2.2 Prefixes commonly used . . . 8 Table 2.3 Units derived from SI . . . 9 Table 2.4 SI units and conversion factors . . . 10 Table 2.5 Parameters frequently used . . . 12 Table 2.6 Lower and Higher Heating Values of solid, liquid,
and gaseous fuels . . . 13 Table 2.7 Conventional densities of liquid fuels . . . 13 Table 2.8 Ratios between end users energy and purchased energy
(see also Chaps. 18 and 20) . . . 14 Table 2.9 A review of the main flow meters . . . 21 Table 3.1 Correlation matrix between population and primary
energy consumption per person . . . 26 Table 3.2 Specific energy consumption of manufacturing
industries . . . 29 Table 4.1 Typical higher heating values of waste . . . 41 Table 4.2 Operating parameters of various batteries . . . 44 Table 4.3 Operating parameters of fuel cells . . . 45 Table 4.4 Operating parameters of hydrogen production
and electricity production by fuel cells . . . 46 Table 5.1 Standard parameters for oil-insulated transformer MT/BT
(normal and reduced losses) . . . 53 Table 5.2 No-load and load losses for a normal-losses transformer
at different load factor values (load factor% ranges
from 120 to 10) . . . 53 Table 5.3 Efficiency of different normal-losses transformers
at the same load power . . . 55 Table 5.4 Total annual losses of different transformers
(as in Table 5.3) . . . 56 Table 5.5 Comparison between total annual losses of two
1,000 kVA transformers (a reduced-losses and a normal-
losses transformer) . . . 56 xxi
Table 6.1 Ignition temperatures of different combustibles . . . 58 Table 6.2 Solid, liquid, and gaseous combustibles and combustion
parameters . . . 60 Table 6.3 Main properties of saturated water (liquid–vapor) . . . 66 Table 6.4 Main properties of superheated water vapor . . . 67 Table 6.5 Hassenstein coefficient values for different combustibles
(Kscoefficient referred to Lower Heating Values of input
fuels and toC) . . . 79 Table 6.6 Minimum stack temperatures and losses for different
combustibles without recovery equipment . . . 83 Table 6.7 Effect of treatment techniques on makeup water
contaminants under ideal operating conditions . . . 87 Table 6.8 Typical ranges of values of permitted pollutant
concentrations from combustion . . . 89 Table 6.9 Main techniques used to reduce NOxemissions . . . 91 Table 6.10 Comparison between two boilers with different
efficiencies (Example 2) fed by natural gas
(34,325 kJ/Sm3as Lower Heating Value)) . . . 96 Table 7.1 Technical parameters for different conducting materials . . . 100 Table 7.2 Voltage drops and losses for different cases
shown in Fig. 7.11 . . . 120 Table 7.3 Voltage drops and losses for different cases
shown in Fig. 7.12 . . . 121 Table 7.4 Comparison between microwave-based dryer
and hot-air dryer . . . 122 Table 7.5 Comparison between two electric motors with different
efficiencies (Example 3) . . . 123 Table 8.1 Average values of thermal conductivity of different
materials at room temperature . . . 128 Table 8.2 Total emissivity average values (ε) . . . 129 Table 8.3 Typical values of heat transfer coefficient (h) . . . 130 Table 8.4 Heat losses from a composite wall (reference Fig. 8.2) . . . 133 Table 8.5 Heat losses from a composite steel pipeline to still air
(see reference Fig. 8.3) . . . 136 Table 9.1 Technical parameters of generation power plants fed
by natural gas, solid biomass, liquid biomass,
and standard coal . . . 143 Table 9.2 Theoretical steam rate . . . 146 Table 9.3 Overall efficiency and ASR coefficient for backpressure
and condensing turbines . . . 149 Table 9.4 Technical parameters for standard gas turbines . . . 154 Table 9.5 Technical parameters for reciprocating engines . . . 156
xxii List of Tables
Table 10.1 Comparison between dissipative and non-dissipative
methods (see Figs. 10.9 and 10.10) . . . 176 Table 11.1 Theoretical values of power requirements for different air
compression processes (1 Sm3/min¼35.3 Sft3/min input air in standard atmospheric conditions, 15.6C, 60F
and 0.1013 MPa, 14.5 psi; see footnotes to Table 2.5) . . . 185 Table 11.2 Characteristics of typical medium-power air compressors . . . . 188 Table 11.3 Power saving versus air-inlet temperatures at constant
inlet pressure and compression ratio (consumptions are compared with power requirements in atmospheric
conditions) . . . 189 Table 11.4 Pressure and leakage losses in air mains and related
power in typical operating conditions . . . 193 Table 11.5 Air requirements of compressed-air end user machines
(absolute 0.7 MPa, 101.5 psi; 100 % load factor) . . . 194 Table 11.6 Energy saving associated with a reduction in the delivery
pressure from 0.9 MPa (130.5 psi) to lower values; inlet air flow rate 30 Sm3/min (1,059 Sft3/min) in standard
atmospheric conditions . . . 196 Table 11.7 Energy saving associated with heat recovery
from a screw compressor . . . 199 Table 12.1 Physical properties of coolants . . . 206 Table 12.2 Comparison between absorption and rotating
compressor systems . . . 218 Table 12.3 Energy saving associated with heat recovery from
a refrigerating plant . . . 219 Table 13.1 Typical loads from occupants in conditioned spaces . . . 230 Table 13.2 Energy saving by heat recovery from exhaust and inlet air . . . 237 Table 14.1 Recommended task surface illuminance . . . 243 Table 14.2 Average values of reflectance coefficients for different
materials and surfaces . . . 244 Table 14.3 Chromaticity of light sources . . . 244 Table 14.4 Suggested color rendering for typical applications . . . 244 Table 14.5 Typical lamp output characteristics . . . 245 Table 14.6 Worksheet for energy-saving evaluation in lighting . . . 251 Table 14.7 Replacement of standard fluorescent lamps
with HF lamps (Example 1) . . . 252 Table 14.8 Comparison between HF fluorescent and LED lamps
(Example 2) . . . 253 Table 15.1 Common sources of waste heat and their range
of temperature . . . 256 Table 15.2 Typical parameters for common heat exchangers . . . 258
Table 15.3 Typical range of values of overall heat-transfer
coefficients U . . . 263 Table 15.4 Shell and tube parameters (Q/ΔTranges between 1,000
and 100,000 W/K) . . . 263 Table 15.5 Double-pipe finned tube parameters (Q/ΔTranges
between 5,000 and 100,000 W/K) . . . 264 Table 16.1 Main technologies for energy recovery in waste treatment . . . 277 Table 17.1 General data XXXX–YYYY . . . 282 Table 17.2 Energy consumption XXXX–YYYY . . . 282 Table 17.3 Share of energy and water cost—XXXX–YYYY . . . 282 Table 17.4 Facilities—XXXX–YYYY . . . 283 Table 17.5 Electrical model—XXXX–YYYY . . . 284 Table 17.6 Natural gas model—XXXX–YYYY . . . 286 Table 17.7 Water model—XXXX–YYYY . . . 287 Table 17.8 Energy KPI performance indicators . . . 289 Table 17.9 Energy saving proposals—XXXX–YYYY . . . 290 Table 17.10 Energy saving due to computer control of facilities . . . 296 Table 19.1 Present worth factor values PWF¼ð1þ1iÞn. . . 306 Table 19.2 Present annuity factor values PAF¼Xn
1
jð1þ1iÞj. . . . 307 Table 19.3 Comparison between general and simplified PW
relationships . . . 308 Table 19.4 Examples of case studies . . . 309 Table 20.1 Basic formulas . . . 312 Table 20.2 Basic data . . . 313 Table 20.3 Basic KPIs . . . 314
xxiv List of Tables
5 Example 1 Sizing of transformers based on maximum efficiency
operation all the year round . . . 54 5 Example 2 For a given rated power, choose between
a reduced-losses transformer and a normal-losses transformer . . . 55 6 Example 1 Calculate the efficiency of an industrial watertube
steam boiler by means of the heat-loss method . . . 94 6 Example 2 For a given rated output power, compare the energy
consumption of two steam boilers having different efficiencies . . . 95 7 Example 1 Calculate the losses in an electric industrial
distribution line with different levels of power factor control . . . 117 7 Example 2 Compare the energy consumption of a microwave
and a thermal dryer system in the textile industry . . . 120 7 Example 3 For a given rated output power, compare
a high-efficiency with a normal- efficiency electric motor . . . 122 8 Example 1 Compare losses from a composite wall with
different thicknesses of insulation (see Fig. 8.2 and Table 8.4) . . . 138 8 Example 2 Compare losses from a composite pipeline with
different thicknesses of insulation (see Fig. 8.3 and Table 8.5) . . . 139 9 Example 1 Cogeneration plant with steam turbine . . . 157 9 Example 2 Cogeneration plant with gas turbine . . . 158 9 Example 3 Cogeneration plant with reciprocating engine . . . 159 9 Example 4 Trigeneration plant with reciprocating engine . . . 161 10 Example 1 Compare the energy consumption of a centrifugal
pump if flow is reduced to 50% of the rated value with
(i) a dissipative method and (ii) a non-dissipative method . . . 175 11 Example 1 Reduction of the compressor discharge pressure
to the real end-user needs . . . 195 11 Example 2 Heat recovery from a screw compressor . . . 196
xxv
12 Example 1 Replacement of an absorption system by a rotating
compressor system . . . 217 12 Example 2 Heat recovery from condensation phase
and lubricant oil cooling . . . 217 13 Example 1 Heat recovery from exhaust air leaving buildings
and inlet air entering buildings . . . 235 13 Example 2 Centralized control of HVAC systems . . . 240 14 Example 1 Replacement of standard fluorescent lamps
and luminaires by high frequency ones (HF fluorescent
lamps and electronic ballast) . . . 250 14 Example 2 Replacement of high frequency lamps and luminaires
(HF fluorescent lamps and ballast) by LED ones . . . 253 15 Example 1 Cooling water-to-process water exchanger
(log-mean method) . . . 269 15 Example 2 Cooling water-to-process water exchanger
(effectiveness-NTU method) . . . 270 15 Example 3 Air-to-exhaust stream exchanger (log-mean method) . . . 271 17 Example A computerized system to control a factory’s facilities . . . 296
xxvi List of Examples
Letter symbols include symbols for physical quantities and symbols for units in which these quantities are measured.
For symbol units see Tables2.4, and2.5.
Quantity symbols are listed below.
Efforts have been made to attribute a single-letter symbol to each physical quantity. Because of the number of topics introduced, some symbols have different meanings according to the context and to the common practice; in these cases, the list of symbols indicates the chapter to which these symbols apply.
A,S Area, section
An Transformer rated power
AE Available energy (isentropic expansion) AHU Air handling unit
ASF Actual steam flow ASR Actual steam rate
c Specific heat
cd Dispersion coefficient (Chap.13) C Capacitor (Chap.7)
C Heat capacity flow rate (Chap.15)
Cp Ratio between shaft power and power available in the wind (Chap.4) Cp Present monetary value (Chap.20)
COD Liquid chemical oxygen demand COP Coefficient of performance (Chap.12) CU Coefficient of utilization (Chap.14) d Length (thickness, diameter)
E Energy
E,P Heat exchanger effectiveness (Chap.13) Ep Electric active energy
Eq Electric reactive energy f Electric frequency f,f* Inflation rate (Chap.20) FT Correction factor (Chap.15) FWF Future worth factor g Gravitational acceleration
(continued) xxvii
(continued)
gc Conversion factor (Chap.10) h Enthalpy per unit mass
h Heat transfer coefficient (Chap.8)
H Head (Chap.10)
H Enthalpy
HHV Higher (or gross) heating value
i Coefficient for life cycle costing (Chap.20) I Investment (Chap.20)
I Electric current
Ip Present investment (Chap.20) IRR Internal rate of return ln Natural logarithm
k Thermal conductivity (Chap.8)
k Ratio of the gas specific heat parametercp/cvat constant pressure (cp) and volume (cv) (Chap.11)
Kc Unburned combustible losses coefficient (Chap.6) Km Karman coefficient (Chap.2)
Ks Hassenstein coefficient (Chap.6) Kv Velocity coefficient (Chap.2)
l,L Length
LHV Lower (or net) heating value
m Mass flow rate
M Mass
n Number of moles (Chap.2, Table2.5) n Life of investment (Chap.20) n Number of phase conductors (Chap.7) nv Rate of ventilation (Chap.13) NACF Net annual cash flow
NTU Number of transfer units (Chap.15) ORC Organic Rankine cycle (Chap.9)
p Pressure
ppm Gas concentration (Chap.6)
P Power (mechanical, electric active power) P,E Heat exchanger effectiveness (Chap.15) PAF Present annuity factor
Pcc Transformer load losses (Chap.5)
Pcn Transformer load losses at rated power (Chap.5) Po Transformer no-load losses (Chap.5)
PL Electric line losses (Chap.7) PW Present worth (Chap.20) PWF Present worth factor (Chap.20)
q Volume flow rate
qs Volume flow rate in standard conditions Q Power as heat transfer rate
(continued)
xxviii List of Symbols
(continued)
Q Electric reactive power (Chap.7) Q Annual revenues (Chap.20)
r Radius
r Interest or discount rate (Chap.20) r Pcn/Po(Chap.5)
rp Compression ratio (Chap.11) R Electric resistance (Chap.7) R Radius of gyration (Chap.4)
R Parameter for heat exchanger calculation (Chap.15) R Universal gas constant (Chap.2, Table2.5) RDF Refusal-derived fuel
RH,ϕ Relative humidity
ROR Investors rate of return (Chaps20and21) Rth¼1/U Overall thermal resistance (Chap.8) S,A Section, area
t,T Temperature (capital letter is generally used for absolute temperatures) TOE Ton oil equivalent
TSR Theoretical steam flow rate (Chap.9) u Internal energy (Chap.11)
U¼1/Rth Overall heat transfer coefficient (Chap.8)
v Specific volume
V Voltage (Chap.7) V Linear velocity
V Volume (Chap.2, Table2.5; in Chap.6) VB Volume of the building (Chap.13) x Load factor (Chap.5)
x Steam quality index (Chaps.6and9) X Electric reactance
Z Compressibility factor
α Instrument flow coefficient (Chap.2)
α Ratio between higher and lower heating value for fuel (Chap.6) δ Electric current density (Chap.7)
ε Thermal emissivity (Chap.8) ε Expansibility factor (Chap.2)
η Efficiency
ρ Mass density
ρ Electrical resistivity of conducting material (Chap.7) σ Stefan–Boltzmann constant
ϕ, RH Relative humidity
Ω Rotational speed
ω Humidity ratio or specific humidity cosφ Electric power factor
Institutions and Associations
ABMA American Boiler Manufacturers Association
ASHRAE American Society of Heating, Refrigerating and Air Conditioning Engineers ASME American Society of Mechanical Engineers
IEC International Electrotechnical Commission IEEE The Institute of Electrical and Electronics Engineers ISO International Organization of Standardization TEMA Tubular Exchanger Manufacturers Association
xxx List of Symbols
Introduction 1
1.1 General Principles of Energy Conversion and Management
In spite of a great diversity among energy end user technologies, due to technical, economic, and environmental factors, energy conversion and management at all levels must be based on a few general principles of proven validity.
Basically, every energy conversion must be performed by reducing related losses at each step, so as to improve the overall energy efficiency.
At the same time, energy management means ensuring that users get all the necessary energy, when and where it is needed, and of the quality requested, supplied at the lowest cost. Of course, all these aims must be achieved while duly safeguarding both production and environmental needs.
To be effective, energy management programs should include four main steps:
(1) analyses of historical data, (2) energy audits and accounting, (3) engineering analyses and investment proposals based on feasibility studies, and (4) personnel training and information.
An energy management program can be organized in several ways, by employing either internal or external consultants, according to the company’s size and the incidence of energy costs on the company’s budget. In order to control energy conversion efficiency at every stage, a few significant energy key performance indexes must be identified before and after undertaking any energy-saving actions.
To obtain the best results, the main steps listed above must be carefully implemented and correlated with one another.
Energy management began to be considered as one of the main functions of industrial management in the 1970s. Faced with the rising price of energy and reports about the approaching exhaustion of world energy resources, both national governments and private companies had to cope with this situation with no further delay. In later years the correlation between energy consumption and environ- mental impact became evident, thus making people worldwide increasingly aware of the matter.
G. Petrecca,Energy Conversion and Management: Principles and Applications,
DOI 10.1007/978-3-319-06560-1_1,#Springer International Publishing Switzerland 2014 1
Inadequate knowledge, however, of energy management techniques and the lack of strong traditions in this kind of capital investment weighed heavily, at the beginning, against a widespread introduction of energy-saving strategies.
Large plants with high energy consumption tackled the problem by retrofitting process plants and facilities. Other industrial sectors, less sensitive to energy, resorted to investments with the shortest possible payback such as heat recovery and reduction of losses, but they put off process modifications, which often involve a more drastic change of production strategies.
The energy shortage in 1980–1990, the first that seriously affected the industrial era, and the following environmental impacts and oscillations in energy prices have made people aware that the energy problem does and will always exist. Therefore, energy-saving technologies have markedly influenced both component and plant designs, and users have become increasingly accustomed to making decisions on energy with regard to more than mere payback considerations.
Large plants and buildings seek energy managers with a good knowledge of technical and economic disciplines, since they play an important role in developing industrial strategies. Mechanics and thermodynamics have traditionally been the base in this educational field; but the spread of information technologies and power electronic systems suggests that electrical and thermodynamics approaches need to be interconnected and that technicians must be prepared to work within this broader context.
University students should have the opportunity to prepare themselves for these jobs; people already working in industry should try to integrate practical knowledge with basic theoretical principles in order to derive the maximum benefit from previous experience. Managers, who do not have time to study technical problems in detail, need a guide to the essentials in order to make well-founded decisions.
The aim of this book is to give an overall view of energy conversion and management by following the stream of energy from site boundaries to end users.
The author’s philosophy is that most energy conversion problems can be approached through understanding the common principles underly- ing the phenomena.
All the topics are reduced to their essentials by introducing a few basic formulas and data. Basic KPIs, mainly drawn from the author’s consul- tancy experience, are also reported. The tables in Chap.20highlight this approach and give a guidance to help understand and solve any problem by reducing it to a basic formula.
2 1 Introduction
1.2 Energy Transformations in Factories and Buildings
The overall approach to energy management is summarized in Fig.1.1which shows the energy streams from a site’s boundaries to end users and the related transformations:
• Energy is transported to the site as purchased fuel or utilities (electric network, gas pipeline, water pipe, etc.) and it is transformed mostly on site (electrical substation with transformers, boiler plants, cogeneration and trigeneration plants) before reaching the energy users. The energy requested by the end users can also be produced on site by means of renewable sources like sun and wind.
Further transformations in facilities and plants should be made in order to obtain different forms of derived energy suitable for the end users.
Obviously, checking the efficiency of all the transformation plants and keeping it as high as possible is a top priority.
• Energy streams in different forms (electric energy at different voltages, steam, hot water, chilled water, hot oil, compressed air, etc.) are distributed around the site to process and facility end users. Distribution systems are responsible for losses, which should be reduced by means of correct planning and thermal insulation.
• Energy end users around the site perform different operations which lead to end products or services. These make up the output of the site, together with waste (which may or may not contain energy in some form) and wasted energy.
Fig. 1.1 Energy flow through the site boundary
Waste and wasted energy include water, solid and liquid materials (combustible or not), and gases.
Energy can be saved at the end user stage in many ways: by introducing more efficient equipment or process systems, by improving controls, by improving monitoring or metering of energy streams, and by recovering heat and waste.
Waste recovery is closely related to waste quality and to the pollution produced.
Energy flow which crosses the site boundaries can be schematized as in Fig.1.1.
This energy flow chart allows an overall approach to site energy management and provides the guidelines for an energy survey as well as an educational program.
1.3 The Plan of the Book
The book has been conceived both as a textbook for university courses in engineer- ing and as a work of reference for professionals in energy management. Readers are assumed to have a basic knowledge of thermodynamics, heat and mass transfer, electric systems and power electronics, as well as computer programming.
The book comprises20chapters that can be grouped as follows:
• General principles of energy transformation, energy management, and energy sources (Chaps.1–4):
This part aims to give readers a general overview of energy conversion and management, from the energy sources to the end users.
• Transformation plants at the site borders (Chaps.5and6): Electrical substations and boiler plants are examined and suggestions are made on how to improve efficiency.
• Internal electric networks and fluid distribution systems from facilities to end users (Chaps.7and8).
• Cogeneration and trigeneration plants (Chap.9).
• Facility plants to move fluids such as pumps, fans, and compressors (Chaps.10 and11).
• Facility plants such as cooling plants, HVAC systems, and lighting systems (Chaps.12–14).
• Heat recovery from process and facilities: Heat exchangers (Chap.15).
• Waste management and correlation with energy management (Chap.16).
• Energy audits, energy accounting for control and planning, and centralized control (Chap.17).
• The role of education in energy conversion and management (Chap.18).
• Economic analysis of energy-saving investments (Chap.19).
• Conclusion: Basic formulas, data, and KPIs (Chap.20).
Throughout the book boxes highlight the fundamental concepts and some important figures for practical applications.
Examples have been given only for basic cases and mainly for facilities, but they can easily be extended to more complicated situations, including process systems, which at first glance seem quite different from one another, if these are not reduced to their essentials. Technical evaluations are shown at the end of each chapter; data
4 1 Introduction
is generally organized in tables to facilitate elaboration by a standard spreadsheet.
Economic evaluations of each example are shown in Table19.3.
Basic formulas, data, and KPIs that everybody involved in energy conversion should know are reported in Chap.20.
The SI system has been used; for ease of understanding, other units commonly used have been added.
Efforts have been made to attribute a single-letter symbol to each physical quantity. Because of the number of topics introduced, some symbols have different meanings according to the context and to the common practice; in these cases, the list of symbols indicates the chapters to which these symbols apply.
References are at the end of the book in chronological order.
Power and Energy Measurement
Units and Techniques 2
2.1 The SI System and Conversion Factors
The SI system (International System of Units) is a set of definitions and rules which provides an organic and consistent approach for obtaining the units for each quantity.
The SI system is based on seven basic and two supplementary units. The basic units are the following: the kilogram (mass), the meter (length), the second (time), the ampere (electric current), the kelvin (temperature), the candela (luminous intensity), and the mole (molecular substance). The supplementary units are the radian (plane angle) and the steradian (solid angle). The choice, which has been made by the General Conference on Weights and Measures, is always open to changes and integrations.
The SI basic and supplementary units are reported in Table2.1. From these nine units any other SI units can be derived by using the following expression:
Derived unit¼mα1kgα2sα3Aα4Kα5cdα6molα7radα8srα9 where the exponentsα1,α2,α3,α4,α5,α6,α7,α8,α9are positive or negative whole numbers. Each exponent is equal to zero when the derived unit does not depend on the corresponding basic or supplementary unit.
Table 2.2 shows the prefixes which must be used to derive multiples or submultiples of any SI unit. Table2.3shows a few derived units currently used.
It is worth noticing that EU (European Union) countries must use the SI units reported in Table2.1(they are obliged to by European Commission’s recommendations and related national laws). This system has been adopted also by the International Organization of Standardization (ISO).
Table 2.4 lists commonly used units which, however, do not belong to the SI system. Technicians should refrain from using these units.
The table shows the conversion factors from these units to SI units; conversion between two non-SI units can be made by using the ratio between the conversion
G. Petrecca,Energy Conversion and Management: Principles and Applications,
DOI 10.1007/978-3-319-06560-1_2,#Springer International Publishing Switzerland 2014 7
factors of the single units. This is valid also for temperature, if temperature changes are considered (as often occurs in many formulas).
Table2.5lists some parameters frequently used for technical calculations.
2.2 Primary Energy Measurement Units
The primary energy content of combustibles (solid, liquid, or gaseous) is expressed by Lower Heating Values or Higher Heating Values such as kJ/kg or kJ/m3 (SI units). There are other units in common use.
Table 2.1 SI base and
supplementary units Quantity Unit Symbol
Length meter m
Mass kilogram kg
Time second s
Electric current Ampere A
Thermodynamic temperature Kelvin K
Luminous intensity candela cd
Molecular substance mole mol
Plane angle radian rad
Solid angle steradian sr
Table 2.2 Prefixes
commonly used Factor Prefix name Symbol
Multiple
1018 Exa E
1015 Peta P
1012 Tera T
109 Giga G
106 Mega M
103 kilo k
102 hecto h
101 deka da
Submultiple
101 deci d
102 cents c
103 milli m
106 micro μ
109 nano n
1012 pico p
1015 femto f
1018 atto a
Table 2.3 Units derived from SI
Quantity Unit Symbol
Space and time
Area square meter m2
Volume cubic meter m3
Velocity meter per second m/s
Acceleration meter per second squared m/s2
Angular velocity radian per second rad/s
Angular acceleration radian per second squared rad/s2
Frequency Hertz Hz¼cycle/s
Mechanics
Density kilogram per cubic meter kg/m3
Momentum kilogram meter per second kgm/s
Moment of inertia kilogram meter squared kgm2
Force Newton N¼kgm/s2
Torque, moment of force Newton meter Nm
Energy, work, heat quantity Joule J¼Nm
Power Watt W¼J/s
Pressure, stress Pascal Pa¼N/m2
Electricity and magnetism
Electric charge Coulomb C¼As
Electric potential, voltage Volt V¼W/A
Electric field strength Volt per meter V/m
Capacitance Farad F¼C/V¼A s/V
Current density Ampere per square meter A/m2
Magnetic field strength Ampere per meter A/m
Magnetic flux Weber Wb¼Vs
Magnetic flux density Tesla T¼Wb/m2
Inductance Henry H¼Vs/A
Permeability Henry per meter H/m
Resistance Ohm Ω¼V/A
Conductance Siemens S¼A/V
Magnetomotive force Ampere A
Light
Luminous flux lumen Im¼cdsr
Illuminance lux lx¼1 m/m2
Viscosity
Kinematic viscosity square meter per second m2/s
Dynamic viscosity Pascal second Pas
2.2 Primary Energy Measurement Units 9
Table 2.4 SI units and conversion factors
To convert from Symbol To Symbol Multiply by
Length
foot ft meter m 0.3048
inch in meter m 0.0254
mile mi meter m 1,609
Area
square foot ft2 square meter m2 0.0929
square inch in2 square meter m2 0.004645
Volume
cubic foot ft3 cubic meter m3 0.02832
cubic inch in3 cubic meter m3 0.00001639
USA liq gallon gal cubic meter m3 0.0037854
Liter L cubic meter m3 0.001
Mass
pound lb kilogram kg 0.45359
ton(short) ton metric ton, tonne t¼103kg 0.9072
ton(long) ton metric ton, tonne t¼103kg 1.016
barrel(oil) barrel metric ton, tonne t¼103kg 0.137
Force
pound-force lbf Newton N 4.448
kilogram-force kgf Newton N 9.807
Pressure pound-force/
square foot
lbf/ft2 Pascal Pa 47.8788
pound-force/
square inch
lbf/in2 Pascal Pa 6,895
kilogram-force/
square meter
kgf/m2 Pascal Pa 9.807
bar bar Pascal Pa 100,000
atmosphere atm Pascal Pa 101,325
mm H2O mm H2O Pascal Pa 9.7739
inch H2O in H2O Pascal Pa 248.7
Speed, velocity
foot/second
