Dear Marcello,
It became more clear J - thank you very much.
I have a few question to resume our conversation:
1) It doesn’t meter if we consider ventilation, infiltration or coupling flow, there is always true rule: if we define incoming air TRNBuild assume the same amount of ‘outcoming’ air but without any destination? If we would like to give this air destination to e.g. zone A we have define supply air in this zone.
2) If coupling flow is assumed that air “leave” part of its heat in wall? (because wall has some heat capacity)? I can’t find some reason of that in equation in manual but there is difference between balance with flow as coupling flow and supply air.
Regards
Karol
Sent: Friday, November 18, 2011 3:13 PM
To: karol.bandurski@put.poznan.pl
Subject: RE: [TRNSYS-users] energy bilans for Type 56
Dear Damien and Karol,
I agree that the way TRNSYS treats airflow rates between zones could appear misleading. The main concept is that Type 56 has no airflow model (at least if you do not have TRNFLOW).
Indeed, Type 56 needs to know only incoming air, as it assumes, in order to assume air balance of ONE ZONE, that An equal amounts of air is assumed to leave the airnode at the airnode temperature. The destination of the leaving air has no interest from the point of view of the zone.
If you have two zones without infiltrations and ventilation, and one opened door between them, there will be an air exchange between the two zones. For mass balance, the mass airflow rate going from zone A to zone B should be the same than the mass airflow rate from zone B to A. However, in this case, type 56 DOES NOT CHECK air balance, then it is to you to define the two airflow rates with the same value. This is the meaning of the sentence in the section 5.4.1.2: coupling air flow from B to A is not defined automatically.
Therefore, your last sentence is correct, Karol: if you define air from A to B as coupling flow then TRNBuild assume that the same amount of air leaves zone B, BUT IT DOES NOT ASSUME that this air is going to zone A.
About the difference between coupling air flow through wall and between air node, I think that there Is no difference. The possibility to have coupling air flow between nodes has be introduced in TRNSYS 17 because two air nodes could have no adjacent walls.
Best regards.
Marcello CACIOLO
Responsable Outils et Méthodes d'Analyse Energétique
___________________________________________________ 
Cellule Efficacité Energétique
Direction Commerciale
46 Boulevard de la Prairie au Duc BP 40119
44000 Nantes Cédex 2
Tel. 02 40 41 06 57
mail: marcello.caciolo@aximaseitha-gdfsuez.com
P Pensez à l'environnement avant d'imprimer ce message
De : trnsys-users-bounces@cae.wisc.edu [mailto:trnsys-users-bounces@cae.wisc.edu] De la part de Karol Bandurski
Envoyé : vendredi 18 novembre 2011 13:37
À : 'Damien Gondre'
Cc : trnsys-users@cae.wisc.edu
Objet : Re: [TRNSYS-users] energy bilans for Type 56
Damien,
There is something not clear corresponding to issue of coupling flow.
On one hand we have information from section 5.4.1.2 in Multizone Building Manual, page 145 that if I define coupling flow from A to B then I have to take care about balance on my own because coupling air flow from B to A is not defined automatically.
On the other hand there is information in section 5.4.1.11, page 156 (similar to ventilation issue, but a few sentences later, corresponding to coupling air flow): "An equal amounts of air is assumed to leave the airnode at the airnode temperature".
Thirdly I hope that we distinguish coupling air flow through wall (p.125 section 5.2.11.8.5. - this is in the range of my interest) and coupling flow between two airnodes of one zone (p.85 section 5.2.4.10.)
My previous statement should read:
“But if you define air from A to B as coupling flow then TRNBuild assume that the same amount of air leave zone B as QTRANS.”
We are looking for Big Explanatory! ;)
Regards
Karol
From: damien.gondre@gmail.com [mailto:damien.gondre@gmail.com] On Behalf Of Damien Gondre
Sent: Friday, November 18, 2011 11:05 AM
To: Karol Bandurski
Cc: trnsys-users@cae.wisc.edu
Subject: Re: [TRNSYS-users] energy bilans for Type 56
Hi Karol,
I had the same questions a while ago and someone else would probably gives you more trustable answers than me. But I will try to answer you with what I figured out (someone please corrects me if I'm wrong).
"It is mean that if I introduce some supply air (ventilation manager) in zone then TRNBuild assume that there is also exhaust air?"
This is true. If you introduce in zone A 50m3/h of air at Tout for instance, Trnsys will assume that the same amount of air (50m3/h) leaves zone A at temperature of zone A (T_A).
"Then you define ventilation for zone B and parameters of air will be taken from zone A"
That is what I would naturally do but it actually causes convergence problems: if you use T_A to define parameters of air supplied to zone B by the ventilation type, you will use an output of type 56 as an input to type 56. Air supplied in zone B will change temperature in zone B and it will affect temperature in zone A (since zone A and B have an adjacent wall). Then the temperature of air supplied in zone B will change and it will change temperature in zone B and… temperature in zone A (and so on…).
If you still want to do that, you need to use type 93 (input value recall) to supply air with temperature of zone A at timestep (t-1), in zone B at timestep (t).
“But if you define air from A to B as coupling flow then TRNBuild assume that the same amount of air leave zone B as coupling flow, not as exhaust air”
That is not true. If you define air from A to B as a coupling flow TRNBuild doesn’t assume automatically that the same amount of air flows from B to A. (See the note in section 5.4.1.2 in Multizone Building Manual, page 145). When you use coupling flows you have to perform air balance by yourself which means that if you define a coupling from A to B, you will overload zone B.
How do you define exhaust air in zone B to balance the coupling flow from zone A? I don’t know :). Maybe someone else can tell us more about this… I’m looking for this answer too!
Damien.
On Fri, Nov 18, 2011 at 10:13 AM, Karol Bandurski <karol.bandurski@put.poznan.pl> wrote:
Hi!
Thanks for this quotation Damien but I don’t understand what is mean.
It is mean that if I introduce some supply air (ventilation manager) in zone then TRNBuild assume that there is also exhaust air?
Let us assume the situation:
I have ventilator in zone A but there is no ventilator in zone B. Between zone A and B is wall with door. I calculated that air supply to zone A flows to zone B.
This quotation say to me (in above situation):
you should define ventilation for zone A (supply air) then TRNBuild assumes the same amount of exhaust air for this zone but without any destination. Then you define ventilation for zone B and parameters of air will be taken from zone A, TRNBuild again assume the same amount of exhaust air, without any destination. But if you define air from A to B as coupling flow then TRNBuild assume that the same amount of air leave zone B as coupling flow, not as exhaust air.
1) It is true???
If YES:
2) What does TRNBuild assume for infiltration? If during infiltration air is supplied to zone then how it is ejected form there?
3) If coupling flow is assumed then air “leave” part of its heat in wall? (because wall has some heat capacity)
Thanks again Damien for you tip, but
I am asking for more explanation!
Regards
Karol
From: Damien Gondre [mailto:damien.gondre@insa-lyon.fr]
Sent: Thursday, November 17, 2011 2:26 PM
To: Karol Bandurski
Cc: trnsys-users@cae.wisc.edu
Subject: Re: [TRNSYS-users] energy bilans for Type 56
Hi Karol,
I have never used energy balances for zones so I don't know what Qvent, Qtrans or Qsolgain represent, but have you looked in the multizone building manual, section 5.4.1.11, page 156 : "Equal amounts of air are assumed to leave the airnode at the airnode temperature".
I don't know if it helps or not, but I think it might change your vision of how the energy balance is defined.
Regards,
Damien.
On Thu, Nov 17, 2011 at 1:28 PM, Karol Bandurski <karol.bandurski@put.poznan.pl> wrote:
Hi,
I has modeled two version of one family house:
a. with mechanical ventilation
b. with natural ventilation + exhaust fans in dirty rooms (bathroom, WC, Kitchen)
Then I has define balance output Ntype 904 (Energy Balance for Zones) for one zone of this house.
The balance is seems to me false because in TRNBuild in Ventilation Manager I can define only supply air ventilation. So, QVENT represents only heat from supply air, heat connect with exhaust air is probably contained in QTRANS. QTRANS has influence on temperature of walls, so maybe QSOLGAIN is also not so accurate?
My question:
It is true?
How can I change it?
Does TRNFlow change this imperfection? (I don’t have this soft, I has only Contam)
Regards,
Karol
------------------------------------------------
Karol Bandurski MSc.
Institute of Environmental Engineering
Poznan University of Technology
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