VRF cooling issue: overestimate fan power at low load

[yujiex]

Issue overview

The simulated fan power is larger than the calculated fan power for runtime fraction < 1 cases. The following shows the difference between simulated and calculated fan power when the terminal unit is in cooling mode (heating coil RTF = 0) and heating mode (cooling coil RTF = 0)

The minimum fan power is calculated using information from this object

Fan:VariableVolume,
    TU1 VRF Supply Fan,      !- Name
    VRFAvailSched,           !- Availability Schedule Name
    0.5,                     !- Fan Total Efficiency
    400,                     !- Pressure Rise {Pa}
    0.595,                !- Maximum Flow Rate {m3/s}
    FixedFlowRate,                !- Fan Power Minimum Flow Rate Input Method
    0,                       !- Fan Power Minimum Flow Fraction
    0.415,                       !- Fan Power Minimum Air Flow Rate {m3/s}
    0.9,                     !- Motor Efficiency
    1,                       !- Motor In Airstream Fraction
    0.09,                   !- Fan Power Coefficient 1
    0,                       !- Fan Power Coefficient 2
    0,                       !- Fan Power Coefficient 3
    0.91,                   !- Fan Power Coefficient 4
    0,                       !- Fan Power Coefficient 5
    TU1 VRF DX HCoil Outlet Node,  !- Air Inlet Node Name
    TU1 VRF Fan Outlet Node,         !- Air Outlet Node Name
    General;                 !- End-Use Subcategory

defect files

• idf and epw file:
  fan.zip

• excel output:
  eplusout_before_fan_correct_cooling.xlsx

Details

Some additional details for this issue (if relevant):

• Platform (Mac 13.3)
• Version of EnergyPlus (22.2)
• Unmethours link or helpdesk ticket number

Checklist

Add to this list or remove from it as applicable. This is a simple templated set of guidelines.

• Defect file added (list location of defect file here)
• Ticket added to Pivotal for defect (development team task)
• Pull request created (the pull request will have additional tasks related to reviewing changes that fix this defect)