Stack effect airflow

[kldjonge]

Another work-in-progress pull request so you can track my work more easily. I still had commits on my fork related to the contam-modelica airflow verification of PPD12 with o.a missing inputs.

The others (most) are mostly because I already merged the current master and the branch hasn't yet. Maybe we can merge the current master in the stackeffectairflow branch?

[kldjonge]

My guess is that the pull request by @Mathadon: #1322

Also deals with an issue that needed changing to the internal wall, a connection was missing which was causing issues: 2af1282

@Mathadon , you deleted the density column:
a302cfe

Probably this was to solve the same problem?

[Mathadon]

@kldjonge I deleted the density column because it's the only case where a density column was used in two-port configuration, which did not seem like a good idea. As far as I could tell anyway. :)

[Mathadon]

But I indeed noticed that a connection was missing :)

[kldjonge]

Well, it actually is nececarry to keep it. The general rule (when stack effect is included) is that each time that a zone is coupled to a flow element, a density must be used to account for the height difference between the center of the zone and the opening based on the temperature/density of the zone it connects to.

As an internal wall component connects to a zone a both sides, the 1 density column that is part of the default implementation is not sufficient.

[Mathadon]

@kldjonge sorry I made I typo in my post, should be:

"I deleted the density column because it's the only case where a density column was used in one-port configuration, which did not seem like a good idea. As far as I could tell anyway. :)"

Does it make sense then? I.e. the one-port configuration has no stack effect, nowhere, and the two-port configuration does have stack effect.