This is the second edition of HVAC Water Chillers and Cooling Towers, which was first published in 2003. In the past 8 years, there have been major improve�ments to many chiller and cooling tower elements resulting in both improved performance and lower operating costs. Climate change and a new focus on “green” design have significantly impacted the selection of refrigerants and the application of chilled water systems. And, finally, the expanded use of digital controls and variable frequency drives, along with reapplication of some older technologies, especially ammonia-based absorption cooling, has necessitated updating of this text in a new, second edition.
There are two fundamental types of HVAC systems designed to satisfy build�ing cooling requirements: direct expansion (DX) systems, where there is direct heat exchange between the building air and a primary refrigerant, and secondary refrigerant systems that utilize chilled water as an intermediate heat exchange media to transfer heat from the building air to a refrigerant.
Chilled water systems are the heart of central HVAC cooling, providing cool�ing throughout a building or a group of buildings from one source. Centralized cooling offers numerous operating, reliability, and efficiency advantages over individual DX systems and, on a life cycle basis, can have significantly lower total cost. And, chilled water systems, especially with water-cooled chillers, represent a much more “green” design option.
Every central HVAC cooling system is made up of one or more refrigeration machines or water chillers designed to collect excess heat from buildings and reject that heat to the outdoor air. The water chiller may use the vapor compres�sion refrigeration cycle or an absorption refrigeration cycle (utilizing either lith�ium bromide or ammonia solutions). Vapor compression refrigeration compressors may be reciprocating, scroll, helical screw, or centrifugal type with electric or gas-fired engine prime movers.The heat collected by any water chiller must be rejected to the atmosphere.
This waste heat can be rejected by air-cooling in a process that transfers heat directly from the refrigerant to the ambient air or by water-cooling, a process that uses water to collect the heat from the refrigerant and then to reject that heat to the atmosphere. Water-cooled systems offer advantages over air-cooled systems, including smaller physical size, longer life, and higher operating efficiency (in turn resulting in reduced greenhouse gas contribution and atmospheric warming). The success of their operation depends, however, on the proper sizing, selection, application, operation, and maintenance of one or more cooling towers that act as heat rejecters.
The goal of this book is to provide the HVAC designer, the building owner and his or her operating and maintenance staff, the architect, and the mechanical contractor with definitive and practical information and guidance relative to the application, design, purchase, operation, and maintenance of water chillers and cooling towers. The first half of the book discusses water chillers, while the sec�ond half addresses cooling towers
