[TRNSYS-users] Decrease of temperature with Type 56

[Augustin CUQ]

Hi Marion,

Thank you for your answer.

I am looking at Top, but the same phenomenon can be observed if you look at
Tair.
The problem cannot be seen with the global chart of TRNSys. The best is to
plot the derivative as the substraction between the temperature at *t *time
and the one at *t-1, *dividing by the time step (0,25 hr). Then you will
observe the problem focusing on the derivative from the time step 1195 to
1210.

Concerning the NTypes, I did what you have suggested to me:
 - Surface temperatures follow the same trend as the operative ones. A peak
for derivative value can be observed.
 - Radiative and convective gains are positives while the heating device is
switched on and remains equal to 0 from the interruption time step. QCOMIs
derivative function evolves as the operative temperature does...

Find attached the results I have just plotted. I cannot explain why this
appears... I have tried to change the walls' components but the problem
doesn't desappear...

Looking at the results have you got any suggestion to solve this problem? Do
you think it could be a problem of stability due to TRNBuild calculation?



2011/6/7 Marion Hiller <hiller at transsolar.com>

>  Augustin,
>
>
>
> Assuming no infiltration/ventilation the behaviour of the zone air
> temperature as well as the operative temperature after switching
>
> off gains depend on the surface temperatures.
>
> I run the attached files, but the entities on the online weren’t sufficient
> to see your problem (Top and Text).
>
> If you talk about temperature are you looking at Top or Tair?
>
>
>
> You may check surface temperatures TSI and the NTYPE QCOMI for heat
> transfer.
>
> I suggest add Onlines with all relevant entities like TSI, TAIR, QCOMI,
> rad. GAINS, conv. Gains etc. .
>
>
>
> Marion
>
>
>
>
>  ------------------------------
>
>
> *Von:* Augustin CUQ [mailto:augustin.cuq at gmail.com]
> *Gesendet:* Montag, 6. Juni 2011 18:17
> *An:* Aaron J. Danenberg
> *Cc:* trnsys-users
> *Betreff:* Re: [TRNSYS-users] Decrease of temperature with Type 56
>
>
>
> Dear Aaron,
>
> Thanks for answering so quickly.
>
> Changing the infiltration rates (setting it to 0) doesn't change the
> phenomenon I describe... I had tried but the decrease can still be observed.
> Concerning the weather data, I wanted to simplify as much as I could the
> model, to be sure the problem wasn't the result of the weather variations.
> If you delete the heating device (or set it to 0) and the soil temperature
> too, you will see that the temperature decreases logically up to 0°C.
> The conditions for the external walls are set to a default value 0, in
> order to be sure the evolution of the temperature remains constant (increase
> when there is a heating device and decrease when there is no heating
> device). In that way, the temperature shouldn't increase after stopping the
> heating device (it is the case in my simulation for the third time step
> following the interruption of heating), and it shouldn't decrease so fast
> for the two time steps following this interruption (comparing with the
> evolution after 4 time steps = 1 hour).
>
> BR.
>
> Augustin CUQ
>
> 2011/6/6 Aaron J. Danenberg <danenberg at hartford.edu>
>
> Augustin,
>
>
>
> You infiltration rates seem relatively high (0.6ACH), if it is this high I
> would assume you are in a windy location, or the building is old and leaky
> (or you include some mechanical ventilation in this number).  Since the
> building is well insulated, I would assume the problem lies within your
> control (signal) scheme, or double checking your ACH assumption against the
> results of a blower door test.  I use the data reader and TMY2 weather data
> to define the conditions for external walls.  I did not understand how you
> defined your conditions for the external walls, that may be something you
> want to double check on, I cannot say if it is incorrect or correct, but may
> be a likely source of your problems.
>
>
>
> Aaron J. Danenberg
>
> Graduate Research Assistant
>
> University of Hartford
>
>
>
> *From:* Augustin CUQ [mailto:augustin.cuq at gmail.com]
> *Sent:* Monday, June 06, 2011 10:03 AM
> *To:* trnsys-users
> *Subject:* [TRNSYS-users] Decrease of temperature with Type 56
>
>
>
> Dear all,
>
> I sent a mail two weeks ago to expose the problem I had but it was not very
> clear. So I have made an Excel file to illustrate it.The model has been
> simplified.
>
> It represents a two rooms building, with no internal gain. The outside
> temperature remains constant to 0°C and all the other parameters used by the
> .bui are equals to a default value: 0.
> The only parameter which is a variable input of the model is a heating
> power. It remains constant until the steady state is obtained and then it is
> put to 0.
>
> The variation of the temperature, for the three time steps following the
> stop of the heating device seems to be weird. The decrease of the
> temperature is very fast, then it increases (???) before going down with an
> acceptable derivative value (around 0.3°C/hr).
> Find attached the model I have used.
>
> Can anyone explain to me the reason of this phenomenon?
> Thanks in advance.
>
> Best regards.
>
> --
> Augustin CUQ
>
>
>
>
> --
> Augustin CUQ
>
> Elève-Ingénieur en dernière année à l'Ecole des Mines de Nantes,
>
> Spécialisation en Génie des Systèmes Energétiques
>
> Stagiaire chez ETAMINE, Bureau d'Etudes Techniques en thermique et
> aéraulique et en conseil HQE
>
>
>



-- 
Augustin CUQ
Elève-Ingénieur en dernière année à l'Ecole des Mines de Nantes,
Spécialisation en Génie des Systèmes Energétiques
Stagiaire chez ETAMINE, Bureau d'Etudes Techniques en thermique et
aéraulique et en conseil HQE
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