Re: [EnergyPlus_Support] Can HVAC system take air from earth tubes instead of ambient?

[Jason Kirkpatrick <jason.alan.kirkpatrick@xxxxxxxxx>]

I have found it easier to run two simulations.
The first one simulates the earth-tube only and then outputs the hourly dry bulb and wet bulb temperatures to a .csv file
The second simulation utilizes EMS routines to replace the dry bulb and wet bulb hourly temperatures in the weather file with those found in the .csv output file but only for the outdoor air intake node... See code below:  (note this was done with v.5 so there may be some updating that you need to do for v6)

EnergyManagementSystem:Sensor,
    Earth_Tube_DB_Sched, !Name
    EarthTubeDBSch, ! Output:Variable Index Key Name
    Schedule Value; ! Output:Variable or Output:Meter Name
    
EnergyManagementSystem:Sensor,

    Earth_Tube_WB_Sched, !Name
    EarthTubeWBSch, ! Output:Variable Index Key Name
    Schedule Value; ! Output:Variable or Output:Meter Name

EnergyManagementSystem:Actuator,
    ET_OADB_Override, ! Name

    DOAS Outside Air Inlet, ! Component Name
    Outdoor Air System Node, ! Component Type
    Drybulb Temperature; ! Control Variable
    
EnergyManagementSystem:Actuator,
    ET_OAWB_Override, ! Name
    DOAS Outside Air Inlet, ! Component Name
    Outdoor Air System Node, ! Component Type
    Wetbulb Temperature; ! Control Variable

EnergyManagementSystem:Program,
    SchedOA, ! Name
    SET ET_OADB_Override = Earth_Tube_DB_Sched,
    SET ET_OAWB_Override = Earth_Tube_WB_Sched;

    
EnergyManagementSystem:ProgramCallingManager,
    Schedule OA, ! Name
    AfterPredictorBeforeHVACManagers, ! EnergyPlus Model Calling Point
    SchedOA; ! Program Name 1
    
Output:EnergyManagementSystem,

    Verbose,
    Verbose,
    Verbose;
    
Schedule:File,
    EarthTubeDBSch, !- Name
    Any Number, !- ScheduleType
    W:\M\CALC\ETDB.csv, !- Name of File
    1, !- Column Number
    0, !- Rows to Skip at Top
    8760, !- Number of Hours of Data
    Comma; !- Column Separator

Schedule:File,
    EarthTubeWBSch, !- Name
    Any Number, !- ScheduleType

    W:\M\CALC\ETWB.csv, !- Name of File
    1, !- Column Number
    0, !- Rows to Skip at Top
    8760, !- Number of Hours of Data
    Comma; !- Column Separator

On Sun, Jul 3, 2011 at 1:20 PM, YuanLu Li <yli006@xxxxxxxxxxx> wrote:

 

I think, you can feed the ET air to a small room (a separate zone) and then exhaust or return it to the OA mixer, or a HVAC system..  

The HVAC system does not know whether the air is from the room or the OA mixer.
 
The OA mixer box is actually an  air splitter, an air  by-pass path, and an air mixer.  The releaf node air is fed to the inlet node via the environment.
 
If the inlet air volume low or zero, all the zone  return air is directed to the HVAC system.
 
You need to decide which part of the building air is to be relieved with an exhaust fan, so that the ET air is not relieved at the OA mixer.
=======================
There may be other ways.  Think of an pratical real system installation and then map it into the EPlus simulation system.
 
The idea is similar to the domestic hot water system.  The water from a tank  to the showers, etc. are thrown away and replaced by the main water supply.
 

 

 Dr. Li  

 

---

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: wasilqayyum@xxxxxxxxxxx
Date: Sun, 3 Jul 2011 14:31:11 +0000
Subject: [EnergyPlus_Support] Can HVAC system take air from earth tubes instead of ambient?

 

Hello all,

I'm simulation earth tubes for pre-cooling.

However, the issue im having is that earth tubes output air directly into a zone (building). But can I have it output air to a HVAC system instead? or have an HVAC accept air from the earth tubes?

Thanks.

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