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Part 1 - Fundamentals of Refrigeration Refrigeration Manual © 1968 Emerson Climate Technologies, Inc. All rights reserved. FOREWORD The practice of refrigeration undoubtedly goes back as far as the history of mankind, but for thousands of years the only cooling mediums were water and ice. Today refrigeration in the home, in the supermarket, and in commercial and industrial usage is so closely woven into our everyday existence it is difficult to imagine life without it. But because of this rapid growth, countless people who must use and work with refrigeration equipment do not fully understand the basic fundamentals of refrigeration system operation. This manual is designed to fill a need which exists for a concise, elementary text to aid servicemen, salesman, students, and others interested in refrigeration. It is intended to cover only the fundamentals of refrigeration theory and practice. Detailed information as to specific products is available from manufacturers of complete units and accessories. Used to supplement such literatureand to improve general knowledge of refrigerationthis manual should prove to be very helpful. © 1968 Emerson Climate Technologies, Inc. All rights reserved. Section 1 Basic Refrigeration Principles Thermodynamics 1-1 Heat 1-1 Temperature 1-1 Heat Measurement 1-2 Heat Transfer 1-2 Change of State 1-3 Sensible Heat 1-3 Latent Heat of Fusion 1-3 Latent Heat of Evaporation 1-4 Latent Heat of Sublimation 1-4 Saturation Temperature 1-4 Superheated Vapor 1-4 Subcooled Liquid 1-4 Atmospheric Pressure 1-4 Absolute Pressure 1-5 Gauge Pressure 1-5 Pressure-Temperature Relationships, Liquids 1-5 Pressure-Temperature Relationships, Gases 1-5 Specific Volume 1-6 Density 1-6 Pressure and Fluid Head 1-6 Fluid Flow 1-7 Effect of Fluid Flow on Heat Transfer 1-7 Section 2 Refrigerants Terminology and Examples 2-1 Pure Fluid 2-1 Mixture and Blend 2-1 Azeotropic Refrigerant Mixture 2-1 Zeotropic Mixture 2-2 Near-Azeotropic Refrigerant Mixture 2-2 How are Components Chosen 2-2 Mixture Behavior 2-3 Azeotrope 2-3 Zeotrope 2-3 Near-Azeotropic Refrigerant Mixtures 2-3 What Happens to Mixture Composition During System Charging? 2-3 Temperature Glide 2-4 What Happens to Refrigerant Mixture Composition During a Leak? 2-5 Types of Refrigerant 2-5 Refrigerants 2-8 Refrigerant 12 2-8 Refrigerant R-401A/B 2-8 Refrigerant R-409A 2-8 Refrigerant 134a 2-8 Refrigerant 22 2-9 Refrigerant R-502 2-9 Refrigerant R-402A 2-9 Refrigerant R-408A 2-9 Refrigerant R-404A 2-9 Refrigerant R-507 2-10 Refrigerant Saturation Temperature 2-10 Refrigerant Evaporation 2-10 Refrigerant Condensation 2-10 Refrigerant-Oil Relationships 2-10 Refrigerant Tables 2-11 Saturation Properties 2-12 Pocket Temperature-Pressure Charts 2-12 Section 3 The Refrigeration Cycle Simple Compression Refrigeration Cycle 3-1 Heat of Compression 3-2 Volumetric Efficiency of the Reciprocating Compressor 3-2 Volumetric Efficiency of the Scroll Compressors 3-4 Effect of Change in Suction Pressure 3-4 Effect of Change in Discharge Pressure 3-4 Effect of Subcooling Liquid Refrigerant with Water or Air 3-4 Effect of Subcooling Liquid Refrigerant by Superheating the Vapor 3-4 Effect of Superheating the Vapor Leaving the Evaporator 3-5 Effect of Pressure Drop in the Discharge Line and Condenser 3-5 Effect of Pressure Drop in Liquid Line 3-5 Effect of Pressure Drop in the Evaporator 3-5 Effect of Pressure Drop in Suction Line 3-6 Internally Compound Two-Stage Systems 3-6 Externally Compound Systems 3-6 Cascade Systems 3-10 Table of Contents © 1968 Emerson Climate Technologies, Inc. All rights reserved. Most users of refrigeration products normally associate refrigeration or air conditioning with cold and cooling, yet the practice of refrigeration engineering deals almost entirely with the transfer of heat. This seeming contradic- tion is one of the most fundamental concepts that must be grasped to understand the workings of a refrigeration or air conditioning system. Cold is really only the ab- sence of heat, just as darkness is the absence of light, and dryness is the absence of moisture. THERMODYNAMICS Thermodynamics is that branch of science dealing with the mechanical action of heat. There are certain fundamental principles of nature, often called laws of thermodynamics, which govern our existence here on Earth. Several of these laws are basic to the study of refrigeration. The first and most important of these laws is the fact that energy can neither be created or destroyed. It can only be converted from one type to another. A study of thermodynamic theory is beyond the scope of this manual, but the examples that follow will illustrate the practical application of the energy law. HEAT Heat is a form of energy, primarily created by the trans- formation of other types of energy into heat energy. For example, mechanical energy turning a wheel causes friction and is transformed into heat energy. When a vapor such as air or refrigerant is compressed, the co