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Poppong,
-----Ursprüngliche
Nachricht-----
Von: trnsys-users-bounces@engr.wisc.edu
[mailto:trnsys-users-bounces@engr.wisc.edu] Im Auftrag von Sakulpipatsin,
P.
Gesendet: Mittwoch, 14. Juni 2006 15:09
An:
trnsys-users@engr.wisc.edu
Betreff: [TRNSYS-users] Inquiry for energy
balance for Zones (NTYPE 904)
Dear
Sir/Madam,
I would like to ask you some questions about energy
balance for Zones (NTYPE 904). The energy balance equation is in ?the Type 56
user? manual? I enclosed the balance information to this
mail.
1.
I used the example of TRNSYS16,
Restaurant, and looked at energy balance for a zone in the example. All hourly
energy balances (BAL_ENERGY), generated by TRNSYS16, are not zero. However the
attached manual says that the values should be always 0. I also did energy
balance for a single zone model (using TYPE 56) and the results were also not
zero. Could you please give me a reason why they are not zero? In a result
file of NTYPE 904, there is a column of ?REL_BAL_ENERGY? What is the
?REL_BAL_ENERGY??
The REL_BAL_ENERGY is
the relative error of the energy balance, in other words, the error in the
energy balance referred to the sum of energy entering a zone (or any
balance room). For the restaurant example and even for the building example
this relative error is far below 1 %.
The absolute "error" in
the energy balance should be 0. Actually TRNSYS TYPE 56 has
a certain tolerance on the energy balance caused by the convention that matrix
inversion is not performed in each iteration call when the difference
of the values are small refered to the previous call.
2.
In the energy balance equation,
what is the QWGAIN? When I did energy balance for those examples (in item 1),
all values of the QWGAIN are zero. Could you please explain why all the
results are zero?
With WALLGAIN you
can define an energy flux to the inside surface of a wall (in kJ/h). If in
the balance the values are 0, no wall gain has been defined in the
building description.
3.
In the energy balance equation,
what is the QTRANS? Does the value equal to summation of difference between
QT_RGain_i and QCOMI for all surfaces covering the zone? The definitions of
QT_RGain_i and QCOMI are in item 4.2.9.6 in the attached file. I thought in
this way because only QT_RGain_i and QCOMI of NTYPE 906 (intem 4.2.9.6 in the
manual) come from the inner surface nodes. And only QTRANS from the energy
balance equation interacts the inner surface nodes (when QWGAIN is zero).
QTRANS is the
energy passing the inner wall surfaces, independently from what is
happening in the wall.
Actually it is the
difference QCOMI (NTYPE19) - QABSI (NTYPE 21) summed for all
surfaces.
Kind regards
Monika
Could you please answer my questions? Thank you very
much.
Best regards,
Poppong Sakulpipatsin,
MSc.
Doctoral researcher, Building Services
Faculty of Architecture, Delft University of Technology
Berlageweg 1, 2628 CR Delft, The Netherlands
Tel.
+31-15-278-5955
Fax +31-15-278-4178
e-mail P.Sakulpipatsin@bk.tudelft.nl
http://bk.tudelft.nl/bt/installaties
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