[TRNSYS-users] Setting "front / back" coupling for interzonal airchange in type 56 - TRNFLOW interaction?

[Marion Hiller]

Philip,

I agree that this definition isn't very clear for adjacent walls.

In general, the first layer of a wall construction is facing the zone/airnode.
A non-adjacent wall is always FRONT. You don't need to define front/back because only one side of the construction can face the zone/airnode.

For adjacent walls only one wall construction is defined and  it isn't clear to which of the 2 zones/airnodes the first layer of the defined wall construction is facing.
Therefore, you need to define FRONT/BACK with respect to your wall construction definition.

Marion



________________________________
Von: TRNSYS-users [mailto:trnsys-users-bounces at lists.onebuilding.org] Im Auftrag von Philip
Gesendet: Mittwoch, 30. Juli 2014 10:10
An: David BRADLEY; trnsys-users at lists.onebuilding.org
Betreff: Re: [TRNSYS-users] Setting "front / back" coupling for interzonal airchange in type 56 - TRNFLOW interaction?

Dear David,

Thanks a lot for your helpful answer!
I got the airflow part right.

However, the front/back issue is not clear to me and I could not find an explanation in the documentation.
Please have a look at the following sketch:

  *   is this the correct setting?

[cid:image001.jpg at 01CFABE4.BE2431D0]



Sorry for the probably easy question, but at least for me it is not totally clear how to define it.

Thanks a lot!!

Philip


On 7/25/2014 9:38 PM, David BRADLEY wrote:
Philip,
  When you define a coupling air flow rate through an ADJACENT wall, a quantity of air from the ADJACENT zone enters the active zone. In your first picture below, 90 kg/h of air would enter zone AT_109 from airnode R_107. If you click on the little green arrow button that allows you to set whether the flow is constant, scheduled, or an input, you will see a note explaining what the conditions of the air entering the zone will be. If you want air to flow the other direction as well (from AT_109 to R_107) you have to define that separately in zone R_107.

  The front/back switch has to do with the thermal model and which surface of the wall is in a given zone.
Kind regards,
 David


On 7/25/2014 08:05, Philip wrote:
Dear All,

I could not find an explanation on the coupling "front/back", see below.

I want to model an inter-zonal airchange between 2 zones (AT_009 and R_007- green arrow in the screenshot), so I have to define one zone as "front" and one as "back" and define the same coupling rate in both zones.

  *   But does it make any difference which is defined as front and which as back?

There is also a TRNFLOW Network that connects some other zones (AT_009 and AT_109 etc. ..) in order to realize night ventilation through an Atrium.

The zone R_007 is not connected to the TRNFLOW network, but I guess it would make sense to link it?

Any help highly appreciated!!!

Thanks, and have a nice weekend,
Philip

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