[TRNSYS-users] Challenges using TRNFLOW

[Jones Marcus]

This one is for all the TRNFLOW experts out there!

We are modeling a large continuous (14000 m3!) air space shaped like a big spiral, and were hoping to use TRNFLOW to investigate the stratification and resulting air flows. There are three additional areas of the building with completely independent air handling units. First question is how best to model each of the three separate AHU's in TRNFLOW, since it requires only ONE network. To connect them all together we made a "crack" type connection with negligible size (flow coefficient) between each zone and a single auxiliary node with fixed to a constant pressure. Is this a good way to link independent networks?

Additionally, in each air handling unit, there is a mixing or return air path, so a large percentage of the conditioned air is recycled as is typical. Because we had problems, we were looking for a "duct" type that would add storage to the loop and maybe help it converge?

Generally we had big simulation problems with our approach, with temperatures beyond the dewpoint, humidities that were unphysically large, and errors such as "PANE TEMPERATURE CALCULATION IS
DIVERGING". We were not able to track down the bug (getting at the data is a big challenge). We have since changed the approach and disabled TRNFLOW, connecting the air handlers through the "ventilation" input in Type 56, but we are still worried about the stratification.

Best regards,

Marcus


MARCUS JONES, MSc

Energy Department

Sustainable Building Technologies



AIT Austrian Institute of Technology

Österreichisches Forschungs- und Prüfzentrum Arsenal Ges.m.b.H.

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