ARI Standards 550/590 and 560 are common industry standards used for rating water chiller performance. ASHRAE/IESNA Standard 90.1–1999, the energy standard, contains minimum full-load and part-load chiller efficiency requirements, as well as requirements for the design and operation of chilled- water systems.
Review—Period Two
▲Load-terminal control
◆Three-way valve
◆Two-way valve
◆Face-and-bypass dampers
▲Parallel configuration
▲Series configuration
▲Primary-secondary
configurationprimary-secondarysystem
Figure 113
Period Two examined the methods of load-terminal control, including using three-way modulating valves, two-way modulating valves, and face-and-bypass dampers. We then examined several common system configurations, including chillers piped in parallel, in series, and in a primary-secondary arrangement.
The majority of the time was spent discussing the design and operation of the primary-secondary (or decoupled) chilled-water system. The primary-secondary system eliminates many of the hydraulic problems associated with multiple- chiller systems. It provides a reliable and energy-efficient supply of chilled water, and its simplicity and flexibility make it easy to design, expand, and operate.
