KIRKPATRICK Synthesis Lectures on Mechanical Engineering Introduction to Refrigeration and Air Conditioning Systems AIR CONDITIONING SYSTEMS AND REFRIGERATION TO INTRODUCTION Theory and Applications Introduction to Allan Kirkpatrick, Colorado State University This text provides background information, description, and analysis of four major cooling system technologies–vapor compression cooling, evaporative cooling, absorption cooling, and gas cooling. Refrigeration and Air Vapor compression systems are currently the primary technology used in most standard domestic, commercial, and industrial cooling applications, as they have both performance and economic advantages over the other competing cooling systems. However, there are many other applications in which evaporative cooling, absorption cooling, or gas cooling technologies are a preferred choice. Conditioning Systems The main focus of the text is on the application of the thermal sciences to refrigeration and air conditioning systems. The goals are to familiarize the reader with cooling technology nomenclature, and provide insight into how refrigeration and air conditioning systems can be modeled and Theory and Applications analyzed. Cooling systems are inherently complex, as the second law of thermodynamics does not allow thermal energy to be transferred directly from a lower temperature to a higher temperature, so the heat transfer is done indirectly through a thermodynamic cycle. Emphasis is placed on constructing idealized thermodynamic cycles to represent actual physical situations in cooling systems. The text also contains numerous practical examples to show how one can calculate the performance of cooling system components. By becoming familiar with the analyses presented in the examples, one can gain a feel for the representative values of the various thermal and mechanical parameters that characterize cooling systems. ABOUT SYNTHESIS Allan Kirkpatrick This volume is a printed version of a work that appears in theSynthesis Digital Library of Engineering and Computer Science. Synthesis lectures provide concise original presentations of important research and development topics, published quickly in digital and print formats. For CLAYPOOL & MORGAN more information, visit our website: http://store.morganclaypool.com Synthesis Lectures on Mechanical Engineering store.morganclaypool.com Introduction to Refrigeration and Air Conditioning Systems Theory and Applications Synthesis Lectures on Mechanical Engineering Synthesis Lectures on Mechanical Engineering series publishes 60–150 page publications pertaining to this diverse discipline of mechanical engineering. The series presents Lectures written for an audience of researchers, industry engineers, undergraduate and graduate students. Additional Synthesis series will be developed covering key areas within mechanical engineering. Introduction to Refrigeration and Air Conditioning Systems: Theory and Applications Allan Kirkpatrick 2017 MESMs Barometers Toward Vertical Position Detecton: Background Theory, System Prototyping, and Measurement Analysis Dimosthenis E. Bolanakis 2017 Vehicle Suspension System Technology and Design Avesta Goodarzi and Amir Khajepour 2017 Engineering Finite Element Analysis Ramana M. Pidaparti 2017 Copyright © 2017 by Morgan & Claypool All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means—electronic, mechanical, photocopy, recording, or any other except for brief quotations in printed reviews, without the prior permission of the publisher. Introduction to Refrigeration and Air Conditioning Systems: Theory and Applications Allan Kirkpatrick www.morganclaypool.com ISBN: 9781681731735 paperback ISBN: 9781681731742 ebook DOI 10.2200/S00793ED1V01Y201708MEC006 A Publication in the Morgan & Claypool Publishers series SYNTHESIS LECTURES ON MECHANICAL ENGINEERING Lecture #6 Series ISSN Print 2573-3168 Electronic 2573-3176 Introduction to Refrigeration and Air Conditioning Systems Theory and Applications Allan Kirkpatrick Colorado State University SYNTHESIS LECTURES ON MECHANICAL ENGINEERING #6 M &C Mor & gancLaypool publishers ABSTRACT This text provides background information, description, and analysis of four major cooling sys- tem technologies—vapor compression cooling, evaporative cooling, absorption cooling, and gas cooling. Vapor compression systems are currently the primary technology used in most standard domestic, commercial, and industrial cooling applications, as they have both performance and economic advantages over the other competing cooling systems. However, there are many other applications in which evaporative cooling, absorption cooling, or gas cooling technologies are a preferred choice. The main focus of the text is on the application of the thermal sciences to refrigeration and air conditioning systems. The goals are to familiarize the reader with cooling technology nomenclature, and provide insight into how refrigeration and air conditioning systems can be modeled and analyzed. Cooling systems are inherently complex, as the second law of thermo- dynamics does not allow thermal energy to be transferred directly from a lower temperature to a higher temperature, so the heat transfer is done indirectly through a thermodynamic cycle. Emphasis is placed on constructing idealized thermodynamic cycles to represent actual physical situations in cooling systems. The text also contains numerous practical examples to show how one can calculate the performance of cooling system components. By becoming fa- miliar with the analyses presented in the examples, one can gain a feel for the the representative values of the various thermal and mechanical parameters that characterize cooling systems. KEYWORDS refrigeration, air conditioning, vapor compression, evaporative cooling, absorption cooling, chillers vii Contents Preface ........................................................... ix Acknowledgments ................................................. xi 1 Introduction to Cooling Technologies .................................. 1 1.1 Introduction . 1 1.1.1 Cooling Technologies . 2 1.2 Brief History of Cooling Technologies . 3 1.2.1 Refrigeration . 3 1.2.2 Air Conditioning . 4 1.3 Thermodynamic Background . .5 1.3.1 Thermodynamic Properties . 5 1.3.2 Energy Equation, Heat, and Work . 6 1.4 Psychrometrics . 8 1.4.1 Properties of Air-water Vapor Mixtures . 8 1.4.2 Adiabatic Saturation and Wet Bulb Temperatures . 11 1.4.3 Weather Data . 13 1.4.4 Psychrometric Chart . 15 1.5 Thermal Comfort . 19 2 Vapor Compression Cooling Cycles ................................... 25 2.1 Introduction . 25 2.2 Carnot Refrigeration Cycle . 25 2.3 Vapor Compression Cycle Operation . 26 2.4 Vapor Compression Cycle Analysis . 27 2.5 Efficiency Measures—COP, EER, and SEER . 30 2.6 Refrigerants . 32 2.7 Effect of Evaporator and Condenser Temperature . 37 2.8 Part Load Performance . 41 2.9 Multistage Vapor Compression Systems . 43 viii 3 Evaporative, Absorption, and Gas Cooling Cycles ....................... 45 3.1 Evaporative Cooling . 45 3.1.1 Introduction. 45 3.1.2 Direct Evaporative Cooling . 45 3.1.3 Indirect Evaporative Cooling . 47 3.2 Absorption Refrigeration Cycles . 51 3.2.1 Introduction. 51 3.2.2 Absorption Cycle Operation . 53 3.2.3 Absorption Cycle Analysis . 55 3.3 Gas Refrigeration Cycle . 58 3.3.1 Introduction. 58 3.3.2 Thermodynamic Analysis . 58 4 Cooling Equipment ................................................ 61 4.1 Introduction . 61 4.2 Heat Exchangers . 61 4.2.1 Heat Transfer in Heat Exchangers . 63 4.2.2 Heat Exchanger Analysis . 65 4.3 Condensers . 67 4.3.1 Introduction. 67 4.3.2 Condensation Heat Transfer. 69 4.3.3 Evaporative Condensers . 71 4.4 Evaporators . 71 4.4.1 Introduction. 71 4.4.2 Boiling Heat Transfer . 73 4.5 Cooling Coils . 74 4.6 Cooling Towers . 75 4.7 Compressors . 76 4.7.1 Introduction. 76 4.7.2 Reciprocating Compressors . 77 4.7.3 Centrifugal Compressors . 80 4.7.4 Compressor Lubrication . 86 4.8 Expansion Valves . 86 Bibliography ...................................................... 89 Author’s Biography ................................................. 91 ix Preface This text is written as a tutorial for engineering students and practicing engineers whowantto become more familiar with the analysis of the performance of air conditioning and refrigeration systems. The level of the text is at the advanced mechanical engineering student level. Itassumes basic knowledge of thermodynamic properties, open system equations, and psychrometrics. A short review of these topics is given in Chapter 1. Chapter 2 discusses the analysis and performance of vapor compression systems and refrigerants, while Chapter 3 covers evapora- tive, absorption, and gas cooling systems. Finally, Chapter 4 provides detailed information and analysis of the heat exchangers, pumps, and compressors used to assemble an air conditioning and refrigeration system. Allan Kirkpatrick August 2017 xi Acknowledgments Many thanks to my family; Susan, Anne, Matt, Rob, and Kristin, for their unflagging support while this text was being written. Allan Kirkpatrick August 2017 1 CH A P T E R 1 Introduction to Cooling Technologies 1.1 INTRODUCTION This text provides background information, description, and analysis of four major cooling technologies—vapor compression cooling, evaporative cooling, absorption cooling, and gas cooling. Vapor compression systems are currently the primary technology used in most stan- dard domestic, commercial,