Re: [TRNSYS-users] TRNBUILD/TRNFLOW air density

TRNFlow is an adapted version of COMIS.

You may check the literature:

TN 29: Fundamentals of the Multizone Air Flow Model- COMIS

The COMIS Fundamentals contains an overview about Infiltration modelling as well as the physics and the mathematics behind the COMIS model.

The COMIS (standalone) is available from https://github.com/jasondegraw/COMIS3

Marion

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Dipl.-Ing. Marion Hiller
TRANSSOLAR Energietechnik GmbH
Stuttgart - Munich - New York - Paris

t: +49.711.67976.0 f: +49.711.67976.11

www.transsolar.com/

KlimaEngineering - Technologien für energieeffizientes Bauen und Nutzerkomfort in Gebäuden
Transsolar Energietechnik GmbH, Curiestrasse 2, 70563 Stuttgart

Amtsgericht Stuttgart - HRB 23347 / Steuernummer: 99073/00911 / USt-IdNr.: DE 152272639
Geschäftsführer: Matthias Schuler, Thomas Auer, Stefan Holst, Dieter Schnelle

Von: Arnaud Candaele [mailto:frodooon@gmail.com]
Gesendet: Dienstag, 11. Juli 2017 13:12
An: Marion Hiller <Hiller@Transsolar.com>
Cc: TRNSYS users mailing list at OneBuilding.org <trnsys-users@lists.onebuilding.org>
Betreff: Re: [TRNSYS-users] TRNBUILD/TRNFLOW air density

Thank you.

But in TRNFLOW then, how is density updated with temperature? What is the mathematical relationship?

Thanks a lot,

Arnaud.

2017-07-11 10:45 GMT+02:00 Marion Hiller <Hiller@transsolar.com>:

Arnaud,

For the coupling of the models, the nodal airflow model and the thermal energy balance model, everything is based on mass flows.

For the airflow model (TRNFLow) the density in an airnode varies whereas for the thermal model of Type56 the density doesn’t change. It’s defined in the dialog “properties”.

I’m not aware the densities are available as outputs.

Furthermore, if I try plotting the TRNFLOW output "ACHZ" for on zone in a very simple test model (external node --> duct --> zone --> fan ---> external node), to get an idea of the volumetric flow rate, i got zero value (although other indicators, such as FLNEL show me coherent mass flow rate).

In general, output 210 “ACHZ” should give an output. You may sent your simple examples to your distributor and ask for further help.

Marion

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Dipl.-Ing. Marion Hiller
TRANSSOLAR Energietechnik GmbH
Stuttgart - Munich - New York - Paris

www.transsolar.com/

KlimaEngineering - Technologien für energieeffizientes Bauen und Nutzerkomfort in Gebäuden
Transsolar Energietechnik GmbH, Curiestrasse 2, 70563 Stuttgart

Amtsgericht Stuttgart - HRB 23347 / Steuernummer: 99073/00911 / USt-IdNr.: DE 152272639
Geschäftsführer: Matthias Schuler, Thomas Auer, Stefan Holst, Dieter Schnelle

Von: TRNSYS-users [mailto:trnsys-users-bounces@lists.onebuilding.org] Im Auftrag von Arnaud Candaele via TRNSYS-users
Gesendet: Donnerstag, 6. Juli 2017 15:03
An: trnsys-users@cae.wisc.edu
Betreff: [TRNSYS-users] TRNBUILD/TRNFLOW air density

Hello,

I'd like to know where I could find details about the assumptions taken in TRNBUILD/TRNFLOW to compute the air density is a room (or in a TRNFLOW link). None of the outputs give this information (if I'm not mistaken!), and all flow rates are expressed in kg/h.

Furthermore, if I try plotting the TRNFLOW output "ACHZ" for on zone in a very simple test model (external node --> duct --> zone --> fan ---> external node), to get an idea of the volumetric flow rate, i got zero value (although other indicators, such as FLNEL show me coherent mass flow rate).

Can somebody help me on this subject?

Best regards,

Arnaud.