[TRNSYS-users] Inquiry for energy balance for Zones (NTYPE 904)

[hotline]

Poppong,
 
 -----Ursprüngliche Nachricht-----
Von: trnsys-users-bounces at engr.wisc.edu [mailto:trnsys-users-bounces at engr.wisc.edu] Im Auftrag von Sakulpipatsin, P.
Gesendet: Mittwoch, 14. Juni 2006 15:09
An: trnsys-users at 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 at bk.tudelft.nl 

	http://bk.tudelft.nl/bt/installaties <http://bk.tudelft.nl/bt/installaties> 

	 

	 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/trnsys-users-onebuilding.org/attachments/20060616/585d98b6/attachment-0005.htm>