Air Conditioning and Refrigeration

626 Pages·2006·20.248 MB·English

by  Rex Miller, Mark R. Miller

Air Conditioning
and
Refrigeration
This page intentionally left blank
Air Conditioning
and
Refrigeration
R M
EX ILLER
Professor Emeritus
State University College at Buffalo
Buffalo, New York
M R. M
ARK ILLER
Professor, Industrial Technology
The University of Texas at Tyler
Tyler,Texas
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DOI: 10.1036/0071467882
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Contents
Preface xv Voltmeter 25
Acknowledgments xvii Ohmmeter 26
Multimeter 26
1 Air-Conditioning and Wattmeter 27
Refrigeration Tools Other instruments 28
Air–Filter Efficiency Gages 28
and Instruments
Air-Measurement Instruments 28
Performance Objectives 2 Humidity-Measurement Instruments 29
Tools and Equipment 2 Vibration and Sound Meters 29
Pliers and Clippers 2 Service Tools 30
Fuse Puller 2 Special Tools 31
Screwdrivers 2 Vacuum Pumps 32
Wrenches 3 Vacuum Pump Maintenance 34
Soldering Equipment 3 Vacuum Pump Oil Problems 34
Drilling Equipment 4 Operating Instructions 34
Knives and Other Insulation-Stripping Tools 5 Evacuating a System 35
Meters and Test Prods 6 Charging Cylinder 35
Tool Kits 7 Charging Oil 36
Gages and Instruments 9 Changing Oil 37
Pressure Gages 9 Mobile Charging Stations 37
Gage Selection 10 Tubing 37
Line Pressure 11 Soft Copper Tubing 37
Effects of Temperature on Gage Performance 12 Hard-Drawn Copper Tubing 38
Care of Gages 12 Cutting Copper Tubing 39
Gage Recalibration 12 Flaring Copper Tubing 40
Thermometers 13 Constricting Tubing 41
Pocket Thermometer 13 Swaging Copper Tubing 41
Bimetallic Thermometers 15 Forming Refrigerant Tubing 42
Thermocouple Thermometers 16 Fitting Copper Tubing by Compression 43
Resistance Thermometers 16 Soldering 43
Superheat Thermometer 17 Soft Soldering 44
Superheat Measurement Instruments 17 Silver Soldering or Brazing 46
Halide Leak Detectors 21 Testing for leaks 47
Setting Up 21 Cleaning and Degreasing Solvents 47
Lighting 22 Review Questions 47
Leak Testing the Setup 22
Adjusting the Flame 22
Detecting Leaks 22 2 Development of Refrigeration
Maintenance 22
Electrical Instruments 23 Performance Objectives 50
Ammeter 23 Historical Development 50
v
Structure of Matter 50 Turns Ratio 78
Elements 51 Transformer Applications 78
Atom 51 Semiconductors 78
Properties of Matter 51 Diodes 78
Pressure 52 Transistors 79
Pressure Indicating Devices 52 Silicon-controlled Rectifier (SCR) 80
Pressure of Liquids and Gases 53 Bridge circuits 80
Atmospheric Pressure 53 Wheatstone Bridges 80
Gage Pressure 53 Variable Resistor 81
Absolute Pressure 53 Sensors 81
Compression Ratio 54 Temperature Elements 82
Temperature and Heat 54 Humidity Elements 82
Specific Heat 55 Controllers 83
Heat Content 55 Single-Element Controllers 84
Sensible Heat 55 Dual-Element Controllers 86
Latent Heat 55 Actuators 86
Other Sources of Heat 56 Electro-Hydraulic Actuators 86
Refrigeration Systems 56 Thermal Actuators 87
Refrigeration from Vaporization Auxiliary Devices 88
(Open System) 56 Electronic Compressor Motor Protection 88
Basic Refrigeration Cycle 56 Operation 88
Capacity 57 Troubleshooting the Control 89
Refrigerants 57 Restoring Service 91
Refrigerant Replacements and the Atmosphere 58 Review Questions 91
Review Questions 59
4 Solenoids and Valves
3 Voltage, Current, and
Resistance Performance Objectives 94
Industrial Solenoids 94
Performance Objectives 62 Tubular Solenoids 94
Ohm’s Law 62 Frame Solenoids 94
Series Circuits 62 Applications 97
Parallel Circuits 64 Solenoids as Electromagnets 97
Current in a Parallel Circuit 64 Solenoid Coils 97
Resistance in a Parallel Circuit 65 Servicing Coils 97
AC and DC Power 65 Solenoid Valves in Circuits 98
Phase 66 Refrigeration Valve 99
Power in DC Circuits 66 Review Questions 100
Power Rating of Equipment 67
Capacitors 67
How a Capacitor Works 68 5 Electric Motors: Selection,
Capacity of a Capacitor 69 Operational Characteristics,
Dielectric Failure 69 and Problems
Basic Units of Capacitance 69
Working with Capacitive Values 69 Performance Objectives 102
Capacitor Types 70 Construction of an Induction Motor 102
Capacitor Tolerances 73 Single-Phase Motors 103
The AC Circuit and the Capacitor 73 Shaded-Pole Motor 103
Uses of Capacitors 75 Split-Phase Motor 103
Inductance 75 Capacitor-Start Motor 104
Four Methods of Changing Inductance 75 Sizes of Motors 104
Self-Inductance 75 Cooling and Mounting Motors 105
Mutual Inductance 76 Direction of Rotation 106
Inductive Reactance 77 Synchronous Motor 107
Uses of Inductive Reactances 77 Theory of Operation 107
Transformers 77 Synchronous Motor Advantages 108
Transformer Construction 77 Properties of the Synchronous Motor 108
vi Contents
Electric Motors 109 Bimetallic Thermostats 146
Starting the Motor 109 Thermostat Construction and Wiring 147
Repulsion-Induction Motor 110 Defrost Controls 147
Capacitor-Start Motor 111 Defrost Timer Operation 147
Permanent Split-Capacitor Motor 112 Hot-Gas Defrosting 148
Shaded-Pole Motor 112 Motor Burnout Cleanup 148
Split-Phase Motor 114 Procedure for Small Tonnage Systems 148
Polyphase-Motor Starters 115 Procedure for Large Tonnage
Reduced-Voltage Starting Methods 116 Systems 150
Primary-Resistor Starting 116 Reading a Schematic 150
Autotransformer Starting 119 Review Questions 152
Part-winding Starting 120
Wye-delta or Star-delta Starters 121
Multispeed Starters 123 6 Refrigerants: New and Old
Consequent-Pole Motor Controller 124
Full-Voltage Controllers 127 Performance Objectives 156
Starting Sequence 129 Classification of Refrigerants 156
Protection Against Low Voltage 129 Common Refrigerants 156
Time-Delay Protection 129 Freon Refrigerants 158
Electric Motors: Their Uses, Operation, Molecular Weights 158
and Characteristics 132 Flammability 158
Motor Rotation 133 Toxicity 158
Variable-Speed Drives 133 Skin Effects 158
Troubleshooting Electric Motors with Oral Toxicity 158
a Volt-Ammeter 133 Central Nervous System (CNS) Effects 159
Split-Core AC Volt-Ammeter 134 Cardiac Sensitization 161
Testing for Grounds 135 Thermal Decomposition 162
Testing for Opens 135 Applications of Freon Refrigerants 162
Checking for Shorts 136 Reaction of Freon to Various Materials
Testing Squirrel-Cage Rotors 136 Found in Refrigeration Systems 165
Testing the Centrifugal Switch in a Split-Phase Metals 165
Motor 136 Plastics 165
Test for Short Circuit Between Run and Refrigerant Properties 166
StartWindings 136 Pressure 166
Test for Capacitors 136 Temperature 166
Using the Megohmmeter for Volume 166
Troubleshooting 138 Density 167
Insulation-Resistance Testing 138 Enthalpy 167
Measuring Insulation Resistance 139 Flammability 168
Power Tools and Small Appliances 139 Capability of Mixing with Oil 168
Hermetic Compressor Systems 140 Moisture and Refrigerants 168
Circuit Breakers and Switches 140 Odor 168
Coils and Relays 140 Toxicity 169
AC Motor Control 140 Tendency to Leak 169
Motor Controller 141 Detecting Leaks 169
AC Squirrel-Cage Motor 141 Sulfur Dioxide 169
Enclosures 142 Carbon Dioxide 169
Code 142 Ammonia 170
Protection of the Motor 142 Methyl Chloride 170
Contactors, Starters, and Relays 142 Ban on Production and Imports
Motor-Overload Protector 142 of Ozone-Depleting Refrigerants 170
Motor-Winding Relays 143 Phase-out Schedule for HCFCs,
Solenoid Valves 143 Including R-22 170
Refrigeration Valve 144 Availability of R-22 171
Application 144 Cost of R-22 171
Operation 144 Alternatives to R-22 171
Installation 145 Servicing Existing Units 171
Temperature Controls 145 Installing New Units 171
Contents vii
Servicing Your System 172 Air-Cooled Condensers 194
Purchasing New Systems 172 Water-Cooled Condensers 194
Air Conditioning and Working with Halon 172 Hermetic Compressors 194
General Information 172 Compressor Types 194
Leak Repair 173 Newer Models Designations and Coding 202
Trigger Rates 173 Hermetic Compressor Motor Types 205
When Additional Time Is Necessary 173 Resistance Start-Induction Run 205
Relief from Retrofit/Retirement 173 Capacitor Start-induction Run 206
System Mothballing 174 Capacitor Start and Run 206
EPA-Certified Refrigerant Reclaimers 174 Permanent Split Capacitor 206
Newer Refrigerants 174 Compressor Motor Relays 207
Freon Refrigerants 174 Current-type Relay 207
Classifications 174 Potential-type Relay 207
Properties of Freons 175 Compressor Terminals 207
Physical Properties 175 Built-up Terminals 208
Refrigerant Characteristics 176 Glass Quick-Connect Terminals 209
Critical Temperature 176 Motor Mounts 209
Latent Heat of Evaporation 177 Crankcase Heaters 209
Specific Heat 177 Electrical Systems for Compressor
Power Consumption 177 Motors 212
Volume of Liquid Circulated 178 Normal-Starting Torque Motors (RSIR) with a
Handling Refrigerants 178 Current-Type Relay 212
Storing and Handling Refrigerant Cylinders 178 High-Starting Torque Motors (CSIR) with a
Lubricants 178 Current-Type Relay 215
R-134a Refrigerant 179 High-Starting Torque Motors (CSIR) with a
R-134a Applications 180 Two-Terminal External Overload and a
R-12 Systems—General Considerations 180 Remote-Mounted Potential Relay 219
R-12 Medium/High Temperature Refrigeration High-Starting Torque Motors (CSR) with
(>0°F evap) 180 Three-Terminal Overloads and
R-12 Low Temperature Refrigeration Remote-Mounted Relays 222
(<20°F evap) 180 PSC Motor with a Two-Terminal External
R-401B 180 Overload and Run Capacitor 223
R-402A 180 PSC Motor with an Internal Overload
R-402B 181 (Line Breaker) 224
Reclaiming Refrigerant 181 CSR or PSC Motor with the Start Components
Description 181 and an Internal Overload or Line
Compressor 182 Breaker 225
Oil Separator 182 Compressors with Internal Thermostat, Run
Condenser 183 Capacitor, and Supplementary Overload 226
Filter Drier 183 CSR or PSC Motor with Start Components,
Accumulator/Oil Trap 183 Internal Thermostat, and Supplementary
Operation of the Unit 183 External Overload 227
Recovery Plus/Recovery Operations 184 Compressor Connections and Tubes 230
Storage Cylinder Cooling 185 Process Tubes 230
Recycle Operation 185 Other Manufacturers of Compressors 230
Recharge Operation 187 Rotary Compressors 230
Service Operation 187 Stationary Blade Rotary Compressors 230
Test Operation 187 Rotating Blade Rotary Compressors 233
Control Circuits 187 Screw Compressors 233
Troubleshooting 189 Single Screw 235
Troubleshooting Approach 189 Twin Screw 238
Review Questions 189 Making the Rotors 238
Scroll Compressors 238
Scroll-Compression Process 238
7 Refrigeration Compressors
Operation 239
Performance Objectives 192 Scroll Compressor Models 239
Condensers 192 Review Questions 239
viii Contents