Sensor location for variable-volume-flow control at the secondary chilled-water distribution loop

Abstract

A method to determine the 'best' differential pressure sensor location for pump speed control in a variable-volume-flow chilled water distribution system has been presented by Lau. In this Note, Lau's method is reviewed and alternative expressions for determining the sensor location and pumping requirement are derived, which include the effects of water pressure drop across the chilled water coils. Neglecting this will lead to overestimation of the improvement on the valve authority and the reduction in pumping pressure. Issues related to this method of control, including pump energy saving and water balancing are discussed