Variable flow: the quest for system energy efficiency.

Author(s) : EPPELHEIMER D. M.


Varying condenser water flow has long been used as a method of controlling head pressure in water-cooled refrigeration systems. This method of head pressure control has been applied successfully on systems with scroll, reciprocating, heli-rotor, and centrifugal compressors. Condenser water flow is altered either by bypassing the condenser via a three-way valve or by throttling flow with a two-way valve. Today, the affordability and potential energy savings of adjustable-speed drives make this the preferred method of varying flow. In the quest for greater energy savings, many designers propose to vary the flow of water through the evaporators of chillers also. This feat is not as easily accomplished as the first. There are system designs that allow variable flow of chilled water at the system level while maintaining constant flow through the chiller evaporator. Yet in spite of the risk and the presence of other variable options, some still wish to vary the flow of chilled water through the evaporator by large proportions. Can it be done? Of course! However, there are a few engineering problems that must be tackled to accomplish this feat. This paper delineates those problems.


  • Original title: Variable flow: the quest for system energy efficiency.
  • Record ID : 1997-2367
  • Languages: English
  • Source: ASHRAE Transactions.
  • Publication date: 1996/06/23
  • Document available for consultation in the library of the IIR headquarters only.


See other articles from the proceedings (42)
See the conference proceedings