Chilled Water Plant Design Guide energydesignresources December 2009 TABLE OF CONTENTS 1. Overview ....................................................................................................................... 1-1 Introduction ................................................................................................................... 1-1 Target Audience .............................................................................................................1-1 Organization of Material ................................................................................................ 1-2 How to Use the Guide ................................................................................................... 1-3 2. Chilled Water Plant Loads ........................................................................................... 2-1 Understanding Loads and Their Impact on Design ........................................................2-1 Peak Loads Overview ..............................................................................................2-3 Annual Load Profiles Overview ...............................................................................2-4 Oversizing / Undersizing Considerations ................................................................ 2-4 Determining Peak Loads ................................................................................................ 2-6 Calculations/Simulations ........................................................................................2-6 Site Measurements ..................................................................................................2-7 Rules of Thumb ......................................................................................................2-8 Determining Hourly Load Profiles .................................................................................2-8 Computer Simulation Models................................................................................. 2-8 Site Measurements ................................................................................................2-10 3. Chilled Water Plant Equipment .................................................................................. 3-1 Introduction ................................................................................................................... 3-1 Water Chillers ................................................................................................................ 3-1 Manufacturer Data .................................................................................................3-1 Refrigeration Cycle .................................................................................................3-2 Refrigerants .............................................................................................................3-3 Water Chiller Components ............................................................................................ 3-5 Compressors ...........................................................................................................3-5 Evaporators ...........................................................................................................3-12 Condensers ...........................................................................................................3-14 Safety Controls, Accessories, and Options ............................................................ 3-15 Performance Characteristics and Efficiency Ratings ..............................................3-18 Heat Rejection ..............................................................................................................3-24 Manufacturer Data ...............................................................................................3-24 Cooling Towers ....................................................................................................3-24 Air-Cooled Refrigerant Condensers ......................................................................3-32 Evaporative Condensers ........................................................................................3-34 Pumps .......................................................................................................................... 3-35 Manufacturer Data ...............................................................................................3-35 Pump Types ..........................................................................................................3-36 Pump Performance Curves ...................................................................................3-37 Selecting Pumps ....................................................................................................3-39 Pump Installation and Operation ......................................................................... 3-44 Variable-Speed Drives ..................................................................................................3-44 Manufacturer Data ...............................................................................................3-45 Power Quality Issues .............................................................................................3-46 Drive System Efficiency ........................................................................................3-46 VSD Accessories and Considerations .................................................................... 3-47 COOLTOOLS™ CHILLED WATER PLANT DESIGN GUIDE - TABLE OF CONTENTS i 4. Hydronic Distribution Systems ................................................................................... 4-1 Chilled Water Systems ................................................................................................... 4-1 Introduction ...........................................................................................................4-1 Constant-Flow Chilled Water Systems ................................................................... 4-2 Variable-Flow Chilled Water Systems .....................................................................4-7 Variable-Flow System Design Considerations .......................................................4-16 Condenser Water Systems ............................................................................................ 4-33 Introduction .........................................................................................................4-33 Choosing the Style of Cooling Tower ...................................................................4-33 Locating the Condenser Water Pumps.................................................................. 4-34 Piping Multiple Chillers and Cooling Towers ...................................................... 4-36 Piping for Waterside Economizers ........................................................................ 4-40 Auxiliary Condenser Water Circuits ..................................................................... 4-42 Piping Heat Recovery Options ............................................................................. 4-43 5. Controls and Instrumentation ..................................................................................... 5-1 Introduction ................................................................................................................... 5-1 Choosing Instrumentation Control and Monitor Points .........................................5-1 Point Justification ...................................................................................................5-1 Operating Environment for Controls and Instrumentation .................................... 5-2 Network Connections to Equipment Instrumentation............................................ 5-2 Sensors ........................................................................................................................... 5-3 Typical End to End Accuracy Requirements ...........................................................5-3 Temperature Sensors ...............................................................................................5-4 Humidity Sensors ...................................................................................................5-6 Liquid Flow Sensors ................................................................................................5-7 Pressure Sensors ......................................................................................................5-9 Electric Current Sensors ........................................................................................5-10 Electric Power Sensors ..........................................................................................5-11 Gas Flow Sensors ..................................................................................................5-13 Control Valves ..............................................................................................................5-14 Valve Types ..........................................................................................................5-14 Valve Selection Criteria .........................................................................................5-15 Controllers ................................................................................................................... 5-17 Minimum DDC Controller requirements ............................................................ 5-17 Interfacing with Chillers and Chiller Networks .................................................... 5-18