.Buildings.Applications.DataCenters.ChillerCooled.Controls.CoolingMode

Information

Controller that outputs if the chilled water system is in Free Cooling (FC) mode, Partially Mechanical Cooling (PMC) mode or Fully Mechanical Cooling (FMC) mode.

The waterside economizer is enabled when

1. The waterside economizer has been disabled for at least 20 minutes, and
2. T_CHWR > T_WetBul + T_TowApp + deaBan1

The waterside economizer is disabled when

1. The waterside economizer has been enabled for at least 20 minutes, and
2. T_{WSE_CHWST} > T_{WSE_CHWRT} - deaBan2

The chiller is enabled when

1. The chiller has been disabled for at leat 20 minutes, and
2. T_{WSE_CHWST} > T_CHWSTSet + deaBan3

The chiller is disabled when

1. The chiller has been enabled for at leat 20 minutes, and
2. T_{WSE_CHWST} ≤ T_CHWSTSet + deaBan4

where T_{WSE_CHWST} is the chilled water supply temperature for the WSE, T_WetBul is the wet bulb temperature, T_TowApp is the cooling tower approach, T_{WSE_CHWRT} is the chilled water return temperature for the WSE, and T_CHWSTSet is the chilled water supply temperature setpoint for the system. deaBan 1-4 are deadbands for each switching point.

References

• Stein, Jeff. Waterside Economizing in Data Centers: Design and Control Considerations. ASHRAE Transactions 115.2 (2009).

Revisions

• July 24, 2017, by Yangyang Fu:
  First implementation.