blockMappingWithoutWSE

Information

Block that resets maximum cooling tower speed setpoint yMaxTowSpeSet, controls head pressure control valve position yHeaPreConVal or condenser water pump speed yConWatPumSpeSet for plants without water side economizers. The development follows ASHRAE Guideline 36-2021, section 5.20.10 head pressure control, part 5.20.10.3, part 5.20.10.4, and 5.20.10.7.

1. For each chiller, map chiller head pressure control loop signal uHeaPreCon as follows:

• When uHeaPreCon changes from 0 to 50%, reset maximum cooling tower speed setpoint yMaxTowSpeSet from 100% to the minimum speed minTowSpe.
• If the plant has fixed speed condenser water pumps (have_fixSpeConWatPum=true), then: when uHeaPreCon changes from 50% to 100%, reset head pressure control valve position yHeaPreConVal from 100% open to minHeaPreValPos.
• If the plant has variable speed condenser water pumps (have_fixSpeConWatPum=false), then: when uHeaPreCon changes from 50% to 100%, reset condenser water pump speed yConWatPumSpeSet from design speed for the stage desConWatPumSpe to minimum speed minConWatPumSpe. When the pumps are dedicated, speed reset shall be independent for each chiller.

2. When the head pressure control loop is disabled (uHeaPreEna = false), the head pressure control valve shall be closed, or the pump should be disabled; the maximum tower speed setpoint becomes 0.

Parameters

Connectors

Revisions

• January 30, 2019, by Jianjun Hu:
  First implementation.