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Re: [EnergyPlus_Support] HVAC loop Controls - Need help





I just realized that since the system is CAV, supply temperature will vary to meet the load. Then my control approach was completely wrong :P . I did learn a bit more about controls though. Thanks for the help Brent!

Santiago.  



2013/5/6 Griffith, Brent <brent.griffith@xxxxxxxx>
 

The program will accept such input and try to run.  But this input is not going to work very well and will lead to the coils fighting each other if those schedules are constant 12C and 35C.   The cooling coil will open up water flow to try and hit 12C while the heating coil will open up flow to try and hit 35C.  The two controllers operate independently of each other.  Unless you want to model a fault, or have some clever variations in the schedules, this input is not going to work well.  Further there aren?t really air terminal models that are set up to switch between 12C and 35C deck temperatures and still control the zone.

 

The cooling coil controller would work better if the sensor is at the outlet of the cooling coil instead of downstream.  With the heating coil located in between the cooling coil and its sensor, it will have difficulties to make setpoint whenever the heating coil is on.   

 

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Santiago Velez
Sent: Monday, May 06, 2013 7:32 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] HVAC loop Controls - Need help

 

 

Dear group, I have some doubts about how HVAC loops controls work. I've modeled an AHU with cooling and heating water coils (Branch and controller object below). I was wondering how to set setpointmanager objects to control water coils so that supply air temperature is 12 C when cooling and 35 C when heating. I now how to do this with zone reheat coils, but I want to make sure I understand how control work.

 

Is it ok to set 2 Setpointmanagers objects, one for cooling and one heating,  that set different temperatures to different nodes, (eg.  NCUTA-6 Supply Side Outlet 1 set-point 12 C, and NCUTA-6 AHU Heating Coil Air Outlet Node set-point to 35 C for heating)?

 

Thanks in advance.

 

Santiago

 

 

Branch,

    NCUTA-6 AHU Main Branch, !- Name

    autosize,                !- Maximum Flow Rate {m3/s}

    ,                        !- Pressure Drop Curve Name

    Fan:ConstantVolume,      !- Component 1 Object Type

    NCUTA-6 AHU Extract Fan, !- Component 1 Name

    NCUTA-6 Supply Side Inlet,  !- Component 1 Inlet Node Name

    NCUTA-6 AHU Extract Fan Air Outlet Node,  !- Component 1 Outlet Node Name

    Active,                  !- Component 1 Branch Control Type

    AirLoopHVAC:OutdoorAirSystem,  !- Component 2 Object Type

    NCUTA-6 AHU  Outside air system,  !- Component 2 Name

    NCUTA-6 AHU Extract Fan Air Outlet Node,  !- Component 2 Inlet Node Name

    NCUTA-6 AHU Mixed Air Outlet,  !- Component 2 Outlet Node Name

    Passive,                 !- Component 2 Branch Control Type

    Coil:Cooling:Water,      !- Component 3 Object Type

    NCUTA-6 AHU Cooling Coil,!- Component 3 Name

    NCUTA-6 AHU Mixed Air Outlet,  !- Component 3 Inlet Node Name

    NCUTA-6 AHU Cooling Coil Air Outlet Node,  !- Component 3 Outlet Node Name

    Passive,                 !- Component 3 Branch Control Type

    Coil:Heating:Water,      !- Component 4 Object Type

    NCUTA-6 AHU Heating Coil,!- Component 4 Name

    NCUTA-6 AHU Cooling Coil Air Outlet Node,  !- Component 4 Inlet Node Name

    NCUTA-6 AHU Heating Coil Air Outlet Node,  !- Component 4 Outlet Node Name

    Passive,                 !- Component 4 Branch Control Type

    Fan:ConstantVolume,      !- Component 5 Object Type

    NCUTA-6 AHU Supply Fan,  !- Component 5 Name

    NCUTA-6 AHU Heating Coil Air Outlet Node,  !- Component 5 Inlet Node Name

    NCUTA-6 Supply Side Outlet 1,  !- Component 5 Outlet Node Name

    Active;                  !- Component 5 Branch Control Type

 

Controller:WaterCoil,

    NCUTA-6 AHU Cooling Coil Controller,  !- Name

    Temperature,             !- Control Variable

    Reverse,                 !- Action

    Flow,                    !- Actuator Variable

    NCUTA-6 Supply Side Outlet 1,  !- Sensor Node Name

    NCUTA-6 AHU Cooling Coil Water Inlet Node,  !- Actuator Node Name

    autosize,                !- Controller Convergence Tolerance {deltaC}

    autosize,                !- Maximum Actuated Flow {m3/s}

    0.000;                   !- Minimum Actuated Flow {m3/s}

 

 

Controller:WaterCoil,

    NCUTA-6 AHU Heating Coil Controller,  !- Name

    Temperature,             !- Control Variable

    Normal,                  !- Action

    Flow,                    !- Actuator Variable

    NCUTA-6 AHU Heating Coil Air Outlet Node,  !- Sensor Node Name

    NCUTA-6 AHU Heating Coil Water Inlet Node,  !- Actuator Node Name

    autosize,                !- Controller Convergence Tolerance {deltaC}

    autosize,                !- Maximum Actuated Flow {m3/s}

    0.000;                   !- Minimum Actuated Flow {m3/s}

 

AirLoopHVAC:ControllerList,

    NCUTA-6 Controllers,     !- Name

    Controller:WaterCoil,    !- Controller 1 Object Type

    NCUTA-6 AHU Cooling Coil Controller,  !- Controller 1 Name

    Controller:WaterCoil,    !- Controller 2 Object Type

    NCUTA-6 AHU Heating Coil Controller;  !- Controller 2 

 

SetpointManager:Scheduled,

    Air Loop Setpoint Manager/1/1/1 Heating,  !- Name

    Temperature,             !- Control Variable 35 C

    AHU Setpoint Manager Temp Heating,  !- Schedule Name

     NCUTA-6 AHU Heating Coil Air Outlet Node;  !- Setpoint Node or NodeList Name

 

SetpointManager:Scheduled,

    Air Loop Setpoint Manager/1/1/1,  !- Name

    Temperature,             !- Control Variable 12 C

    AHU Setpoint Manager Temp,  !- Schedule Name

     NCUTA-6 Supply Side Outlet 1;  !- Setpoint Node or NodeList Name

 




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