[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [EnergyPlus_Support] DX cooling coil runtime fraction?
Mike:
I am using a constant air volume system, with bypass dx cooling coil.
thanks,
chaoqin
--On Thursday, September 16, 2004 5:06 PM -0500 "Michael J. Witte"
<mjwitte@xxxxxxxx> wrote:
> The HVAC time step is shortened if the system loads or space temperatures
> change too much within a single HVAC time step. The HVAC simulation
> iterates to convergence within each time step, but the "detailed"
> reporting only reports the final result for each time step. I would not
> expect to see this type of behavior in most cases. What type of system
> do you have which is using the DX coil?
>
> Mike
>
>
> On 16 Sep 2004, at 7:48, Rahul Chillar wrote:
>
>>
>> Because the performance of the DX coil is frequently non-linear, the air
>> conditioner model must call the DX coil model several times (iterate) to
>> determine the proper run time fraction to meet the zone load. The cooling
>> convergence tolerance is the error tolerance used to terminate the
>> iteration procedure when the following equation is satisfied:
>>
>> (QZoneLoad- Q Window AC out )/(Qzone Load) < CoolingConvergenceTolerance
>>
>> The maximum number of iterations is currently limited to 15, with a
>> warning message generated if the above equation is not satisfied within
>> the maximum number of iterations.
>>
>> Also while iteration say the first guess value may be 1 then the next
>> will be zero to get the bounds in which the answer exists then it
>> reaches upper bound of say 0.8 then the next lower bound is 0.2 so the
>> anwer is between 0.8 and 0.2. this continues till convergence is
>> reached. Thanks Rahul Chillar
>>
>> zhaicq98 <chaoqinz@xxxxxxxxxxxxxx> wrote:
>> Hi,
>>
>> I have a question about the output object: DX cooling coil runtime
>> fraction. I output the data using detailed output mode. I specify the
>> timestep is 10 minutes in my simulation. When I look at the results,
>> sometimes the output is for each minute. To my understanding, this is
>> related to the convergence of the simulation. Am I right?
>>
>> What surprises me is that during the short timestep (1 or 2 minutes),
>> the runtime fraction of the DX coil varies a lot. For example, for
>> the previous minute, it could be 0.9. Then next minute, it becomes 0.
>> Then next minute it is 0.5. I have no idea how to interpret these
>> data.
>>
>> Thanks!
>>
>>
>>
>> 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 not allowed -- please post any files to the appropriate
>> folder in the Files area of the Support Web Site.
>>
>>
>>
>> Yahoo! Groups SponsorADVERTISEMENT
>>
>>
>> ---------------------------------
>> Yahoo! Groups Links
>>
>> To visit your group on the web, go to:
>> http://groups.yahoo.com/group/EnergyPlus_Support/
>>
>> To unsubscribe from this group, send an email to:
>> EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx
>>
>> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
>>
>>
>>
>> Thanks
>> Rahul Chillar
>> Grad Student
>> Building Systems lab
>> Univ Of Illinois Urbana Champaign
>>
>>
>> ---------------------------------
>> Do you Yahoo!?
>> Express yourself with Y! Messenger! Free. Download now.
>>
>> [Non-text portions of this message have been removed]
>>
>>
>>
>>
>> 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 not allowed -- please post any files to the appropriate
>> folder in the Files area of the Support Web Site.
>>
>> Yahoo! Groups Links
>>
>>
>>
>>
>>
>>
>
>
>
> ========================================================
> Michael J. Witte, GARD Analytics, Inc.
> EnergyPlus Testing and Support
> 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 not allowed -- please post any files to the appropriate
> folder in the Files area of the Support Web Site.
>
>
>
> Yahoo! Groups Sponsor
> ADVERTISEMENT
> [Image: "click"]
> [Image: "width=1"]
>
> __________________________________________________
> Yahoo! Groups Links
>
> * To visit your group on the web, go to:
> http://groups.yahoo.com/group/EnergyPlus_Support/
>
> * To unsubscribe from this group, send an email to:
> EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx
>
> * Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
------------------------ Yahoo! Groups Sponsor --------------------~-->
Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar.
Now with Pop-Up Blocker. Get it for free!
http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/dkFolB/TM
--------------------------------------------------------------------~->
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 not allowed -- please post any files to the appropriate folder in the Files area of the Support Web Site.
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/EnergyPlus_Support/
<*> 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/