Re: [TRNSYS-users] TRNFLOW : air supply problem

Hi everyone.

I got exactly the same issue than Arnaud in TRNFLOW.

Whatever the TRNFlow Outputs I test, results always come out equal to 0.

I have 1 thermal zone (classroom) and I would like to ventilate this room with natural ventilation thanks openings on facade but I can’t obtain the supply air mass flow (for example).

Thank you for your help.

Thomas

De : trnsys-users-bounces@cae.wisc.edu [mailto:trnsys-users-bounces@cae.wisc.edu] De la part de mcdowell@tess-inc.com
Envoyé : jeudi 11 avril 2013 20:10
À : TRNSYS users mailing list at the Solar Energy Lab, UW-Madison
Objet : Re: [TRNSYS-users] TRNFLOW : air supply problem

Arnaud -

I think you need to understand some things about airflows in Type56 before moving to TRNFLOW.

A ventilation flow defined for a zone in the Ventilation Type Manager is only flow into a zone. The flow rate of this air stream can be constant or scheduled as defined in TRNBUILD or defined as an input to the model and connected in Simulation Studio. The temperature and relative humidity of the air stream can be the outdoor conditions, constants defined in TRNBUILD, or inputs from Simulation Studio.

For flow between zones in Type56 you can define coupling airflow rates in the zone manager. Again, these are flows into the zone, so they need to be defined in both zones.

TRNFLOW is adding bulk airflow modeling to the thermal modeling. It may be necessary to use in your case, but an understanding of the basic airflow in Type56 will be helpful in making your decision.

Regards,

Tim

---

Timothy P. McDowell

Executive Vice President

Thermal Energy System Specialists, LLC

22 N Carroll St, Suite 370

Madison, WI 53703

608-274-2577

On 2013-04-10 10:17, Arnaud Candaele wrote:

Hi everyone,

I have a little problem with TRNFLOW. I have a small house, in which I want to bring fresh outside air in some rooms, and extract used air from wet rooms.

For this, I firstly used the "Ventilation Type" Manager to bring air in my rooms.

My first question is : can I also extract air from a room with the Ventilation Type, using a negative mass flow rate for instance ? Or doesn't it make any sense, since from what I understood, this type only brings air with outside conditions in the room, and assumes the equivalent air volume is removed from the room.. (and going "nowhere", so this would only act as a "gain" depending on incoming flow energy)?

Second, also from what I understood : TRNFLOW can not be superposed to this Ventilation Type Manager. I explain : In my case, I use TRNFLOW and define cracks between each room and an external node at constant pressure (I don't want to include wind effect for now), AND I also use the Large Opening Type to represent doors between the rooms. Does that mean I can't use the Ventilation Type Manager ? e.g. can I supply 50m³/h in room1 with the ventilation type manager, while simultaneously connecting this room1 with for example room2 with a large opening link ? Or does the activation of TRNFLOW automatically cancel the Ventilation Type ? Or maybe it doesn't cancel it but no relation is established between the air supply and the rest of the TRNFLOW model ?

To summarize, my last and real question would be : how can you model air supply/extraction in some rooms while using TRNFLOW ? Do we have to create an auxiliary node with outdoor condition and link it with a fan to the zone in which we want to supply air ? Isn't there a simple way to just impose constant (or scheduled) air supply in a room while using TRNFLOW ?

All these questions raised because I had some weird comportment, and I thus tried to monitor air flow in some rooms.. and it stays constantly at 0.

Thank you for your help,

Arnaud.