Design issues of variable chilled-water flow through chillers
- Hartman Co., Marysville, WA (United States)
Variable-speed alternating current (AC) drive technologies are of particular interest for heating, ventilating, and air-conditioning (HVAC) designs because controlling motor speed with variable-frequency AC drives to achieve flow modulation provides an opportunity to capture exceptionally high part-load operating efficiencies. Since HVAC systems spend long hours operating at part-load conditions, improvement in part-load efficiency results in substantial energy savings. Applying variable flow to chilled-water systems is particularly attractive because chilled-water pumping has two associated power costs, directly as pumping power and also as a load on the chiller plant. The small temperature differentials associated with chilled-water systems mean load-side stratification is generally not a concern, but the small temperature differentials do raise concerns about heat transfer at reduced flows. For many building cooling applications, it is possible to design a chilled-water supply and distribution system with only a single variable-flow circuit. However, there are potential pitfalls that must be considered before such a system can be successful. This paper discusses the benefits and problems associated with a single-circuit variable-chilled-water-flow system and offers a chiller plant control strategy that can provide safe, stable, and reliable chiller operation over the entire operating range employed in typical HVAC applications.
- OSTI ID:
- 433773
- Report Number(s):
- CONF-960606--
- Country of Publication:
- United States
- Language:
- English
Similar Records
Optimization of chiller plant's energy consumption utilizing a central EMCS and DDC
Overall chilled water system energy consumption modeling and optimization