[TRNSYS-users] moisture balance

[Marijke Steeman]

Dear Trnsys-users, 

I am simulating a test cell that is humidified and dehumidified for 12hrs each at a rate of 33.33g/hour. 
No moisture buffering occurs and infiltration is set to 0.007hr-1. The temperature in the cell is kept constant
to 20°C. Humidifying the cell is introduced as a zone gain, dehumidification is introduced by ventilating the 
zone with ventilation air at 20°C and at relative humidity calculated from the desired vapour pressure difference
(33.33g/hr is equal to a pressure difference of 118.75Pa). From this simulations, we expect to get a constantly 
varying indoor relative humidity.

When looking at the moisture balance of the zone, it is seen that when dehumidification occurs the balance 
is not equal to zero (as it should be). The sum of the infiltration and ventilation terms do not equal to the change of water stored in the zone air. Because of this the model simulates a larger dehumidification than humidification.
Can anyone help me with this? (Does this occurs because of an iteration problem maybe ?)

In attachement you will find the moisture balance, together with the TPF and BLD file of the model.

Thanks in advance for looking at it !
Kind regards,

Marijke Steeman
PhD-student 
Architecture and Urban Planning
Ghent University 
+32(0)92643752
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