Re: [EnergyPlus_Support] Re: InitializeRootFinder: error

[Fred Buhl <wfbuhl@xxxxxxx>]

The intent was to permit non-zero minimum values for the control valve flow,
for the reason you have given. We'll work to get it working againg.

Fred Buhl

JV Dirkes II wrote:
> Thanks for the details, Brent.
>
> For the reasons cited below (real control valves often unable to close
> fully), I think it will be of practical value to model non-zero
> minimum flows, so I vote for the change!
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Griffith, Brent"
> <brent_griffith@...> wrote:
>   
>> I am afraid it may not be possible to use a non-zero min actuated flow
>> in version 2.1.  It's the Xmax that is the problem.  This value appears
>> to be getting set to zero by the actuated node's value for
>> MassFlowRateMaxAvail (these can be reported with
>> DisplayAdvancedReportVariables diagnostics).  I suspect it may be an
>> internal problem in how the component simulation is interacting with
>> plant loop; this is something we are currently working on fixing for the
>> next release.  Thanks for bringing this to our attention.
>>
>>  
>>
>> The difference in magnitude in the values here is the difference between
>> volume flow rate (input) and mass flow rate (error message). 
>>
>>  
>>
>>  
>>
>>  
>>
>> ________________________________
>>
>> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
>> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of JV Dirkes II
>> Sent: Thursday, April 03, 2008 9:09 AM
>> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
>> Subject: [EnergyPlus_Support] Re: InitializeRootFinder: error
>>
>>  
>>
>> Thank you TJ!
>>
>> Do you know why the small value I used causes this problem? and is
>> there a way to use a non-zero value which will not cause the error? 
>>
>> I used a non-zero value because many control valves cannot shut off
>> completely due to improper actuator selection, and I wanted to include
>> the effects of that in the simulation.
>>
>> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
>> <mailto:EnergyPlus_Support%40yahoogroups.com> , "tjutw" <tjutw@>
>> wrote:
>>     
>>> I guess you just changed one controller. 
>>> In the input file, there are two ""Controller:Simple". You need change
>>> both of them. 
>>>
>>> Tj Ywh
>>>
>>> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
>>>       
>> <mailto:EnergyPlus_Support%40yahoogroups.com> , "JV Dirkes II" <jvd2pe@>
>>     
>>> wrote:
>>>       
>>>> Dear TJ,
>>>>
>>>> You are correct that my value was .000005 in that field (which is
>>>>         
>> not
>>     
>>>> the same as indicated by the message!), but I must be missing
>>>> something; changing the value to 0 results in the same error.
>>>>
>>>> Any other insights?
>>>>
>>>>
>>>>
>>>>
>>>> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
>>>>         
>> <mailto:EnergyPlus_Support%40yahoogroups.com> , "tjutw" <tjutw@> wrote:
>>     
>>>>> If you change the "Min Actuated Flow" in the "Controller:Simple"
>>>>> Object from 0.000005 to 0, then the model runs well. 
>>>>>
>>>>> Tj Ywh
>>>>>
>>>>> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
>>>>>           
>> <mailto:EnergyPlus_Support%40yahoogroups.com> , "JV Dirkes II" <jvd2pe@>
>>     
>>>>> wrote:
>>>>>           
>>>>>> Dear EPlus Forum,
>>>>>>
>>>>>> Can anyone give me a clue what causes the error below? It's the
>>>>>>             
>>> only
>>>       
>>>>>> error in the .err file.
>>>>>>
>>>>>> Thanks! 
>>>>>>
>>>>>> ** Fatal ** InitializeRootFinder: Invalid min/max bounds
>>>>>> XMin=5.000001E-003 must be smaller than XMax=0.000000
>>>>>>
>>>>>>             
>>  
>>
>>
>>
>> [Non-text portions of this message have been removed]
>>
>>     
>
>
>
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>   


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