[TRNSYS-users] Humidity Calculation Error

[Matthias Frechen]

Hi Daniel,

Please check if the mass flow of the AHU is correct. 130 kg/s is huge for this size of the zones, or do you mean 130 kg/h?

Regards,
Matthias Frechen


From: TRNSYS-users [mailto:trnsys-users-bounces at lists.onebuilding.org] On Behalf Of Weber Daniel via TRNSYS-users
Sent: Mittwoch, 29. August 2018 11:27
To: trnsys-users at lists.onebuilding.org
Cc: Weber Daniel <webedani at student.ethz.ch>
Subject: [External] [TRNSYS-users] Humidity Calculation Error

Dear TRNSYS users,

I am modelling a 3D multizone building with Type 56. I have two small zones (volume ~15m^3) which have high coupling air flows to adjacent zones, since they have each one return duct in them. My AHU goes up to 130kg/s and if it's in that state I get the following error:

Small internal timesteps (<0.1% of simulation timestep) used for humidity calculations due to large coupling air flows between zones!

I read that these calculations are affected by the zone volume, its total airflow to other zones and the size of the timestep. Therefore I artificially increased the volume, decreased the airflow of the AHU and decreased the timestep and the error disappeared.

But now my model is not as it should be, is there any other way to get rid of this error without changing zone volumes and coupling air flows?

Thank you for your help and best regards,

Daniel Weber
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