Re: [TRNSYS-users] Setting "front / back" coupling for interzonal airchange in type 56

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@lists.onebuilding.org] Im Auftrag von Philip
Gesendet: Mittwoch, 30. Juli 2014 10:10
An: David BRADLEY; trnsys-users@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?

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