Re: [EnergyPlus_Support] Help with severe error of Coil:Cooling:DX

[Richard Raustad <RRaustad@xxxxxxxxxxxx>]

This warning is posted when the model calculates the coil bypass factor 
at the beginning of the simulation. Even if the coil isn't used during 
the simulation, the bypass factor will still be calculated.

This calculation uses the AHRI rating point of 80/67 for this 
calculation, changing inputs will not alter the inlet condition.

Use a psychrometric routine to calculate the RH at 
12.94C/0.009396985/Standard barometric pressure = 100.62%
Try reducing the total cooling capacity slightly to avoid this error.

If you are autosizing all inputs, check the supply air temperature in 
the Sizing:System object and revise upward slightly.

If you cannot resolve this, you could send this input file to the help 
desk where someone can investigate.

energyplus-support@xxxxxxxx

On 8/29/2013 8:51 AM, weilix88 wrote:
> Hi,
>
> We are encountering a problem when modelling a DX cooling coil with manufacture specs. Here is error message we received:
>
> ** Severe  ** For object = Coil:Cooling:DX:SingleSpeed, name = "COOLING COIL 1"
>     **   ~~~   ** Calculated outlet air relative humidity greater than 1. The combination of
>     **   ~~~   ** rated air volume flow rate, total cooling capacity and sensible heat ratio yields coil exiting
>     **   ~~~   ** air conditions above the saturation curve. Possible fixes are to reduce the rated total cooling
>     **   ~~~   ** capacity, increase the rated air volume flow rate, or reduce the rated sensible heat ratio for this coil.
>     **   ~~~   ** If autosizing, it is recommended that all three of these values be autosized.
>     **   ~~~   ** ...Inputs used for calculating cooling coil bypass factor.
>     **   ~~~   ** ...Inlet Air Temperature     = 26.67 C
>     **   ~~~   ** ...Outlet Air Temperature    = 12.94 C
>     **   ~~~   ** ...Inlet Air Humidity Ratio  = 1.125000E-002 kgWater/kgDryAir
>     **   ~~~   ** ...Outlet Air Humidity Ratio = 9.396985E-003 kgWater/kgDryAir
>     **   ~~~   ** ...Total Cooling Capacity used in calculation = 89387.00 W
>     **   ~~~   ** ...Air Mass Flow Rate used in calculation     = 4.766159 kg/s
>     **   ~~~   ** ...Air Volume Flow Rate used in calculation   = 4.129540 m3/s
>     **   ~~~   **  During Warmup, Environment=BUILDING 101 WINTER, at Simulation time=01/21 00:00 - 00:30
>     **  Fatal  ** Check and revise the input data for this coil before rerunning the simulation.
>
> The surprising thing is that the error results from the cooling coil during winter design when the dry bulb design is set at -8.4 C. EnergyPlus however output inlet air temperature, which in our system is also the mixed air temperature, at 26.67 C...  We changed our setpoint manager: scheduled and setpoint manager: mixed air exactly same as E+ example files but the error is still exist... has anyone had this problem before? Whats the possible reasons to cause this error?
>
>
> Best
> Weili
>
>
>
> ------------------------------------
>
> Primary EnergyPlus support is found at:
> http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
>
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
>
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
>
> Attachments are currently allowed but be mindful that not everyone has a high speed connection.  Limit attachments to small files.
>
> EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
> Yahoo! Groups Links
>
>
>
>

-- 
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
1679 Clearlake Road
Cocoa, FL  32922-5703
Phone:   (321) 638-1454
Fax:     (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu

UCF - From Promise to Prominence: Celebrating 50 Years



------------------------------------

Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx

The primary EnergyPlus web site is found at:
http://www.energyplus.gov

The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/

Attachments are currently allowed but be mindful that not everyone has a high speed connection.  Limit attachments to small files.

EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/join
    (Yahoo! ID required)

<*> To change settings via email:
    EnergyPlus_Support-digest@xxxxxxxxxxxxxxx 
    EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx

<*> To unsubscribe from this group, send an email to:
    EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/