Is it possible to control manually the air flow rate and the water flow rate of a ConstantVolume:CooledBeam?

asked 2019-04-08 16:17:07 -0600

crowmine gravatar image

updated 2019-04-09 07:13:37 -0600

I am trying to manage the temperature of the zones adjusting only the air flow rate to simulate a damper actuator of a VAV box and the chilled water flow rate from the CooledBeam objects to simulate a water valve actuator. To do that, I removed the temperature setpoint manager of the VAV loop (image below) and I override the control of the air flow rate and the chilled water flow rate of the AirTerminal:SingleDuct:ConstantVolume:CooledBeam objects by using ExternalInterface:FunctionalMockupUnitExport:To:Actuator.

ExternalInterface:FunctionalMockupUnitExport:To:Actuator,
    FMU_VAV_Air_FlowRate_Room104,             !- EnergyPlus Variable Name
    Chilled Beam Outlet Node Room104 ZN,      !- Actuated Component Unique Name      
    System Node Setpoint,                     !- Actuated Component Type
    Mass Flow Rate Setpoint,                  !- Actuated Component Control Type
    VAV_Air_FlowRate_Room104,                 !- FMU Variable Name
    0;                                        !- Initial Value

Chilled Beam Outlet Node Room104 ZN is the node between the output of the CooledBeam object and the zone object.

I am also setting the target temperature of the air in the node that is placed just after the Fan:VariableVolume (as is shown in the image below) using the following definition:

ExternalInterface:FunctionalMockupUnitExport:To:Actuator,
    FMU_VAV_Air_Inlet_Node,                   !- EnergyPlus Variable Name
    Node 71,                                  !- Actuated Component Unique Name      
    System Node Setpoint,                     !- Actuated Component Type
    Temperature Setpoint,                     !- Actuated Component Control Type
    VAV_Air_Inlet_Node,                       !- FMU Variable Name
    16;                                       !- Initial Value

The idea is to make EnergyPlus continues to manage the chiller and boiler main loops meanwhile the main zone VAV loop devices are controlled manually as explained above, but the problem is EnergyPlus seems to ignore the changes done externally and also the calculated cooling load is always zero:

** Warning ** Calculated design cooling load for zone=ROOM104 ZN is zero.

The question is: Does anybody knows if this approach is reachable or it should be done using another method?

The building is modeled using OpenStudio, exported to IDF and then includes the remaining definitions (like the ExternalInterface).

Any help would be greatly appreciated.

Zone VAV Main Loop

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