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Autosize electric power get to 0 when I used Fan:SystemModel

asked 2019-01-01 22:15:40 -0600

katsuya.obara gravatar image

updated 2019-01-02 08:11:22 -0600

I am trying to model constant volume fan using Fan:SystemModel referring to this discussion
I could connect Fan:SystemModel to Airloop and get the result.
However, result shows that electric power is 0 as below.
image description
Does anyone know what is causing this situation?
Please also find idf part for Fan:SystemModel as below.

> Fan:SystemModel,
>     2F_WS Supply Fan,        !- Name
>     Office HVAC On (ASHRAE), !- Availability Schedule Name
>     2F_WS Cooling Coil Outlet,  !- Air Inlet Node Name
>     2F_WS Supply Fan Outlet, !- Air Outlet Node Name
>     autosize,                !- Design Maximum Air Flow Rate {m3/s}
>     Discrete,                !- Speed Control Method
>     ,                        !- Electric Power Minimum Flow Rate
> Fraction
>     200,                     !- Design Pressure Rise {Pa}
>     1,                       !- Motor Efficiency
>     1,                       !- Motor In Air Stream Fraction
>     ,                        !- Design Electric Power Consumption {W}
>     PowerPerFlow,            !- Design Power Sizing Method
>     1000.0,                  !- Electric Power Per Unit Flow Rate
> {W/(m3/s)}
>     ,                        !- Electric Power Per Unit Flow Rate Per
> Unit Pressure {W/((m3/s)-Pa)}
>     ,                        !- Fan Total Efficiency
>     ,                        !- Electric Power Function of Flow
> Fraction Curve Name
>     ,                        !- Night Ventilation Mode Pressure Rise {Pa}
>     ,                        !- Night Ventilation Mode Flow Fraction
>     ,                        !- Motor Loss Zone Name
>     ,                        !- Motor Loss Radiative Fraction
>     General,                 !- End-Use Subcategory
>     1,                       !- Number of Speeds
>     1,                       !- Speed 1 Flow Fraction
>     1;                       !- Speed 1 Electric Power Fraction
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answered 2019-01-02 12:21:02 -0600

Were you using a different fan object before and seeing fan electric power values > 0 in the Sizing Report Summary?

It looks like it there are air flow rates being sized in the column to the left of the one circled in your screen shot. This makes me think that EnergyPlus is calculating fan flow needs, but that the fan isn't turning on during the design day. Check the Office HVAC On (ASHRAE) schedule referenced by the Availability Schedule Name input field and make sure that the "WinterDesignDay" and "SummerDesignDay" day types defined in the schedule are not 0 all day. If these day types are NOT defined in the schedule, then EnergyPlus will automatically assign 0 all day, and you would see lines similar to below in your error file ending in *.err generated by EnergyPlus.

** Warning ** ProcessScheduleInput: Schedule:Compact="LOFF ELEC INTLIGHT SCHEDULE" has missing  day types in Through=12/31
**   ~~~   ** Last "For" field=FOR: SUNDAY HOLIDAY
**   ~~~   ** Missing day types="SummerDesignDay","WinterDesignDay","CustomDay1","CustomDay2"
**   ~~~   ** Missing day types will have 0.0 as Schedule Values
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Asked: 2019-01-01 22:15:40 -0600

Seen: 162 times

Last updated: Jan 02