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Re: [EnergyPlus_Support] Doubt About VRF System Warning (Severe)





I should have looked at the Sizing:Zone object. The 3 m3/s flow rate is entered there and used by the program to size the coils.

Sizing:Zone,
  06SUBSOLO:NOBREAK,                                       !- Zone or ZoneList Name
  Flow/Zone,                                               !- Cooling Design Air Flow Method
  3,                                                       !- Cooling Design Air Flow Rate {m3/s}
  Flow/Zone,                                               !- Heating Design Air Flow Method
  3,                                                       !- Heating Design Air Flow Rate {m3/s}

If you look in the eio file, you will see your inputs were used.
 Component Sizing Information, Coil:Cooling:DX:VariableRefrigerantFlow, 06SUBSOLO:NOBREAK VRF COOLING COIL, Design Size Rated Air Flow Rate [m3/s], 3.00000
 Component Sizing Information, Coil:Cooling:DX:VariableRefrigerantFlow, 06SUBSOLO:NOBREAK VRF COOLING COIL, User-Specified Rated Total Cooling Capacity (gross) [W], 55950.76000

I think what is happening here is that this warning should not have been printed. The eio file shows that the capacity is 55950 W, yet this warning shows 49660 W. If you would have autosized the coil capacity, then yes, this warning should be reported.

 ** Warning ** SizeDXCoil: Coil:Cooling:DX:VariableRefrigerantFlow 06SUBSOLO:NOBREAK VRF COOLING COIL
   **   ~~~   ** ...Rated Total Cooling Capacity will be limited by the maximum rated volume flow per rated total capacity ratio.
   **   ~~~   ** ...DX coil volume flow rate (m3/s) = 3.000000
   **   ~~~   ** ...Requested capacity (W) = 36641.887
   **   ~~~   ** ...Requested flow/capacity ratio (m3/s/W) = 8.187E-005
   **   ~~~   ** ...Maximum flow/capacity ratio (m3/s/W) = 6.041E-005
   **   ~~~   ** ...Adjusted capacity (W) = 49660.652


On 11/7/2014 10:52 AM, Ivan Mezzacapa ivan_slip@xxxxxxxxxxx [EnergyPlus_Support] wrote:
Richard, I noticed this problem too.

Maybe it's a bug in EnergyPlus.

I'm entering all the correct information and it keeps expidf different.

Jean, I did not use autosize. Insert the correct data but does not copy the expidf the same way.

The best solution is to modify the data in expidf.

Thank you all!

Técg. Ivan Mezzacapa

Projetista  de Ar Condicionado / Consultor em Eficiência Energética


Celular: (11)9963-9326




To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
Date: Fri, 7 Nov 2014 09:29:36 -0500
Subject: Re: [EnergyPlus_Support] Doubt About VRF System Warning (Severe)

 
The HVACTemplate is not copying the inputs for the VRF coil correctly.
In your input file you have specified 3 m3/s cooling and heating flow rate and 55950.76 W capacity for the coils.

  HVACTemplate:Zone:VRF,
    06SUBSOLO:NOBREAK,       !- Zone Name
    3,                       !- Supply Air Flow Rate During Cooling Operation {m3/s}
    3,                       !- Supply Air Flow Rate During Heating Operation {m3/s}
    55950.76,                !- Cooling Coil Gross Rated Total Capacity {W}


Open the Model.expidf file and find this coil, you will see this:

ZoneHVAC:TerminalUnit:VariableRefrigerantFlow,
  06SUBSOLO:NOBREAK VRF Terminal Unit,                     !- Zone Terminal Unit Name
  autosize,                                                !- Supply Air Flow Rate During Cooling Operation {m3/s}
  autosize,                                                !- Supply Air Flow Rate During Heating Operation {m3/s}

Fan:OnOff,
  06SUBSOLO:NOBREAK VRF Supply Fan,                        !- Name
  autosize,                                                !- Maximum Flow Rate {m3/s}

Coil:Cooling:DX:VariableRefrigerantFlow,
  06SUBSOLO:NOBREAK VRF Cooling Coil,                      !- Name
  Sch_HVAC,                                                !- Availability Schedule Name
  55950.76,                                                !- Gross Rated Total Cooling Capacity {W}
  autosize,                                                !- Gross Rated Sensible Heat Ratio
  autosize,                                                !- Rated Air Flow Rate {m3/s}

Coil:Heating:DX:VariableRefrigerantFlow,
  06SUBSOLO:NOBREAK VRF Heating Coil,                      !- Name
  Sch_HVAC,                                                !- Availability Schedule Name
  55950.76,                                                !- Gross Rated Heating Capacity {W}
  autosize,                                                !- Rated Air Flow Rate {m3/s}


Correct the inputs that show "autosize" to the values you entered in your input file. Then save that file as Model2.idf and run it.

For example, make these changes:

ZoneHVAC:TerminalUnit:VariableRefrigerantFlow,
  06SUBSOLO:NOBREAK VRF Terminal Unit,                     !- Zone Terminal Unit Name
  3,                                                !- Supply Air Flow Rate During Cooling Operation {m3/s}
  3,                                                !- Supply Air Flow Rate During Heating Operation {m3/s}

Coil:Cooling:DX:VariableRefrigerantFlow,
  06SUBSOLO:NOBREAK VRF Cooling Coil,                      !- Name
  3,                                                !- Rated Air Flow Rate {m3/s}

Coil:Heating:DX:VariableRefrigerantFlow,
  06SUBSOLO:NOBREAK VRF Heating Coil,                      !- Name
  3,                                                !- Rated Air Flow Rate {m3/s}


Do the same to correct other issues in the expanded file.



On 11/6/2014 5:30 PM, Ivan Mezzacapa ivan_slip@xxxxxxxxxxx [EnergyPlus_Support] wrote:
Hello everyone!

I am having a problem simulating a VRF system. I created the entire system and the simulation shows me an error that makes no sense for me.

Is reporting that i was inserted data that do not conform to the model input. It's the first time I see this error.

 ** Warning ** SizeDXCoil: Coil:Cooling:DX:VariableRefrigerantFlow 06SUBSOLO:NOBREAK VRF COOLING COIL
   **   ~~~   ** ...Rated Total Cooling Capacity will be limited by the maximum rated volume flow per rated total capacity ratio.
   **   ~~~   ** ...DX coil volume flow rate (m3/s) = 3.000000
   **   ~~~   ** ...Requested capacity (W) = 36641.887
   **   ~~~   ** ...Requested flow/capacity ratio (m3/s/W) = 8.187E-005
   **   ~~~   ** ...Maximum flow/capacity ratio (m3/s/W) = 6.041E-005
   **   ~~~   ** ...Adjusted capacity (W) = 49660.652
  
 ************* SizeDxCoil: Potential issue with equipment sizing for Coil:Cooling:DX:VariableRefrigerantFlow 06SUBSOLO:NOBREAK VRF COOLING COIL
   **   ~~~   ** User-Specified Total Cooling Capacity of 55950.76 [W]
   **   ~~~   ** differs from Design Size Total Cooling Capacity of 49660.65 [W]
   **   ~~~   ** This may, or may not, indicate mismatched component sizes.
   **   ~~~   ** Verify that the value entered is intended and is consistent with other components.
 
  ************* SizeVRF: Potential issue with equipment sizing for AirConditioner:VariableRefrigerantFlow 03SUBSOLO:SUPERVISAOPREDIAL VRF TERMINAL UNIT
   **   ~~~   ** User-Specified Rated Total Heating Capacity of 63000.00 [W]
   **   ~~~   ** differs from Design Size Rated Total Heating Capacity of 55950.76 [W]
   **   ~~~   ** This may, or may not, indicate mismatched component sizes.
   **   ~~~   ** Verify that the value entered is intended and is consistent with other components.
  
 ** Warning ** SizeDXCoil: Coil:Cooling:DX:VariableRefrigerantFlow 06SUBSOLO:DADOSEVOZ VRF COOLING COIL
   **   ~~~   ** ...Rated Total Cooling Capacity will be limited by the minimum rated volume flow per rated total capacity ratio.
   **   ~~~   ** ...DX coil volume flow rate (m3/s) = 0.000000
   **   ~~~   ** ...Requested capacity (W) = 0.000
   **   ~~~   ** ...Requested flow/capacity ratio (m3/s/W) = 0.000
   **   ~~~   ** ...Minimum flow/capacity ratio (m3/s/W) = 4.027E-005
   **   ~~~   ** ...Adjusted capacity (W) = 0.000
   ** Severe  ** Sizing: Coil:Cooling:DX:VariableRefrigerantFlow 06SUBSOLO:DADOSEVOZ VRF COOLING COIL has zero rated air flow rate

If anyone can help, I'd be grateful. Follow the idf.

Best regards,

Técg. Ivan Mezzacapa

Projetista  de Ar Condicionado / Consultor em Eficiência Energética


Celular: (11)9963-9326


-- 
Richard Raustad
Senior Research Engineer
Florida Solar Energy Center
1679 Clearlake Road
Cocoa, FL 32922
Ph: (321)638-1454
http://www.fsec.ucf.edu/en/

Electric Vehicle Transportation Center
http://evtc.fsec.ucf.edu/

-- 
Richard Raustad
Senior Research Engineer
Florida Solar Energy Center
1679 Clearlake Road
Cocoa, FL 32922
Ph: (321)638-1454
http://www.fsec.ucf.edu/en/

Electric Vehicle Transportation Center
http://evtc.fsec.ucf.edu/


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Posted by: Richard Raustad <rraustad@xxxxxxxxxxxx>


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