modelLessCoupled
Validation sequence of controlling tower fan speed based on condenser water return temperature control for less coupled plant
Information
This example validates Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Towers.FanSpeed.ReturnWaterTemperature.Subsequences.LessCoupled.
It shows the calculation of the condenser water supply temperature setpoint and the tower fan speed setpoint.
-
At the first 5 minutes when the plant just enabled, the condenser water supply
temperature setpoint equals to the condenser water return temperature setpoint
minus 50% of the difference between design condenser water supply
(
TConWatSup_nominal) and return (TConWatRet_nominal) temperature of the enabled chiller. Note that in this period, the chillers are not enabled so the fan speed setpoint is 0. -
After 5 minutes, the condenser water supply temperature setpoint equals to
condenser water return temperature setpoint TConWatRetSet minus a temperature
difference that equals 5 minute rolling average of common condenser water
return temperature
TConWatRetless condenser water supply temperatureTConWatSup, sampled at minimum once every 30 seconds. -
The fan speed setpoint is the minimum of:
-
the maximum cooling tower speed setpoint from the head pressure control loop
of the enabled chiller,
uMaxTowSpeSet, -
the tower maximum speed that resets based on the plant partial load ratio,
plrTowMaxSpe, - and the tower speed from the loop mapping based on the PID control for maintaining the condenser water supply temperature at its setpoint.
-
the maximum cooling tower speed setpoint from the head pressure control loop
of the enabled chiller,
Components
Revisions
-
August 12, 2019, by Jianjun Hu:
First implementation.