Improving Campus Chilled Water Systems with Intelligent Control Valves: A Field Study

The degradation of the temperature difference between supply and return flow (known as ΔT degradation) in chilled water systems has been widely observed and documented over the last 25 years. High pumping energy consumption as well as reduced efficiency of the chillers operating under part-load conditions, lead to a decrease of overall system efficiency of chilled water plants. This article describes a field study conducted on two university campuses in Massachusetts and Colorado during the cooling season of 2011. The purpose of this experimental study was to alleviate ΔT degradation problems on both campuses through the use of intelligent pressure-independent control valves, and to quantify the improvements achieved. The MA field results revealed that the intelligent control valves when coupled with a ΔT management strategy have allowed the campus to serve additional cooling load on its campus with the same distribution and central plant system.