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[EnergyPlus_Support] Re: mixing autosized and manual input for a BASEBOARD HEATER:Water:Convective object



Hi Mike,

Thanks for getting back to me so quickly.

Re: 2) I am doing a design day.

Kind regards

-Elmer

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte" 
<mjwitte@...> wrote:
>
> 1.  This will be undersized, because the temperature difference in 
the 
> denominator needs to be a log mean temperature difference which 
includes the 
> leaving air and water temperatures, which you do not know.  (A new 
way of 
> inputting baseboard heat capacity is in the plan for the future.)
> 
> 2.  I am not sure I can explain why the peak output is smaller 
thatn the 
> heating design load.  Are the simulation outputs from "Do the 
design day 
> simulations" or "Do the weather file simulation"?
> 
> 3.  There is a bug in the user specification of UA for the 
baseboard.  This has 
> been fixed for the 1.3.0 release which will be available soon.
> 
> Mike
> 
> 
> On 25 Apr 2006 at 16:45, Elmer Morrissey wrote:
> 
> > Hello all, 
> > 
> > I have a question pertaining to autosizing BASEBOARD 
> > HEATER:Water:Convective objects. 
> > 
> > In the simulation model, the BASEBOARD HEATER:Water:Convective 
> > objects are the only energy tempering devices in the room.
> > 
> > Simulation Run 1: Set the UA from UA = q(loss) / (t(water)-t
(air)) 
> > and autosize water flow rate
> > If I run the simulation and concentrate on one particular zone, 
the 
> > heating design load is 718.55 W. Assuming the room temp is 20C 
and 
> > the water temp is 80C, this would leave a UA of 11.98 W/dK. 
However, 
> > if you use this values in the input configuration for UA: (1) 
the 
> > zone temperature is not consistently maintained at 20C and (2) 
the 
> > maximum load from the heater is never greater than 360.81 W. 
> > 
> > Simulation Run 2: Autosize the UA and water flow rate
> > EnergyPlus calculates the values of UA to be 18.933. The zonal 
> > conditions are spot on. The only odd behaviour is that the max 
> > output from the heater is never greater than 600 W.
> > 
> > Simulation Run 3: Set the UA from the last run and water flow 
rate
> > Now the zonal conditions are not maintained even though nothing 
was 
> > changed except manually configuring the UA syntax to the 
autosized 
> > value from the previous run.
> > 
> > Can anyone explain this?
> > 
> > Kind regards
> > 
> > -Elmer
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 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.
> > 
> > EnergyPlus Documentation is searchable.  Open EPlusMainMenu.idf 
and press the
> > "search" button.
> >  
> > Yahoo! Groups Links
> > 
> > 
> > 
> >  
> > 
> > 
> > 
> > 
> 
> 
> ========================================================
> Michael J. Witte, GARD Analytics, Inc.
> EnergyPlus Testing and Support      
> EnergyPlus-Support@...
>







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