DA-76-07-4 -- Integrated Decentralilzed Chilled Water Systems PDF

Chilled water when applied to air conditioning refrigeration systems is employed as an intermediate heat transfer fluid for the purpose of conveying heat from the space (via a cooling coil) to the refrigeration cycle from which it is normally "pumped" to the higher temperature sink of the outdoor air or an available water source. As technology in chilled water systems developed, it became increasingly evident that in addition to being a thermal conveyor, enabling a physical separation between the load and the source (such that each could be located for the convenient satisfaction of other design parameters), two additional primary advantages emerged:

1. The thermal lag or time constant provided by the inherent storage characteristic of the water provides improvements and simplifications in the control of both the air side apparatus and the refrigeration machinery
2. When multiple points of cooling or conditioning the air are required, the diversity between these loads can be applied to the refrigeration machinery size and operating modes. This feature results in lower investment in refrigeration and dissipation apparatus and a reduced energy consumption by the refrigeration prime mover.

In recent years the centralization of chilled water refrigeration systems has been seen to grow beyond the lines of a single building, lending to the extended use of central chilled water plants serving shopping centers, campus type developments for educational institutions, health care facilities, and office complexes, and municipal-type plants serving multitudes of commercial customer loads.

In many cases, whether by original planning or for lack thereof, a grouping of buildings such as a college campus, or a single large building, has developed a system of separate chilled water systems serving individual buildings or individual portions of a single building.

The concept discussed herein is a method for integrating these isolated chilled water systems into a single system or "loop" to regain the advantages of the centralized system.