[TRNSYS-users] energy bilans for Type 56

Fri Nov 18 04:37:15 PST 2011

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 at gmail.com [mailto:damien.gondre at gmail.com] On Behalf Of
Damien Gondre
Sent: Friday, November 18, 2011 11:05 AM
To: Karol Bandurski
Cc: trnsys-users at 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 at 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 at insa-lyon.fr] 
Sent: Thursday, November 17, 2011 2:26 PM
To: Karol Bandurski
Cc: trnsys-users at 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 at 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.

 <http://www.ee.put.poznan.pl/> Institute of Environmental Engineering

Poznan University of Technology

 <http://www.ee.put.poznan.pl/> www.ee.put.poznan.pl

www.put.poznan.pl <http://www.put.poznan.pl/> 

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