modelDownWithoutOnOff

Information

This example validates Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Staging.Processes.Down.

It shows a process of staging down from stage 2 which requires chiller 1 and chiller 2 to be enabled to stage 1 which requires only chiller 1 to be enabled.

• In stage 2, the design condenser water pump speed is 0.6 and it requires 2 condenser water pumps. The maximum and minimum chilled water flows for chiller 1 and 2 are 1.5 m3/s and 1.0 m3/s.
• In stage 1, the design condenser water pump speed is 0.75 and it requires 1 condenser water pump. The maximum and minimum chilled water flows for chiller 1 are 1.0 m3/s and 0.5 m3/s.

It demonstrates the process as below:

• Before 75 seconds, the plant is not in the staging process.
• At 75 seconds, the plant starts staging down from stage 2 to stage 1. The chiller 2 becomes disabled (uChiLoa[2]=0). Its head pressure control becomes disabled (yChiHeaCon[2]=false). It then slowly closes the chilled water isolation valve of chiller 1. This takes 300 seconds (chaChiWatIsoTim) and finishes the process at 375 seconds.
• After the isolation is closed at 375 seconds, it slowly changes the minimum chilled water flow setpoint from 2 m3/s (for both chiller 1 and 2 operation) to 1 m3/s (for only chiller 1 operation). It takes 300 seconds (byPasSetTim) to finish the change at 675 seconds. The staging process is done.

Components

Revisions

• May 30, 2024, by Jianjun Hu:
  First implementation.