[TRNSYS-users] energy bilans for Type 56

Fri Nov 18 02:05:22 PST 2011

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.****
>
> Institute of Environmental Engineering <http://www.ee.put.poznan.pl/>****
>
> Poznan University of Technology****
>
> www.ee.put.poznan.pl****
>
> www.put.poznan.pl****
>
>  ****
>
>
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users at cae.wisc.edu
> https://mailman.cae.wisc.edu/listinfo/trnsys-users****
>
> ** **
>
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