[TRNSYS-users] several problems with active layer

Adriana Angelotti Adriana.Angelotti at polimi.it
Wed Sep 21 06:15:12 PDT 2005


Dear trnsys users,

I'm having a lot of problems with a simulation with an active layer 
(modelling a sort of capillary system, having many small pipes in parallel;
the panel is split into 4 parts by the autosegmentation in PreBid):
    * at some time steps the fluid outlet temperature of the active 
layer (ouput 58) oscillates without any physical meaning;
    * at these time steps there is a large difference between the 
energy input by fluid to zone obtained as Qalfl (output 59) and 
calculated as m.c.DT;
    * the energy balance of the surface containing the active layer 
(output 906) is never zero, even when water is not flowing into the panel.
The oscilllations are more likely to occurr if the radiant system is 
switched on/off.
Changing the simulation time step from a few minutes to 1 h has no effect.
Convergence and integration relative tolerances are set to 0.001.
No convergence problem is reported in the list file.

I wonder if anybody encountered such problems with active layers simulation.
Any suggestion will be useful, since I really don't know how to go on !

Many thanks in advance

Adriana





----------------------------------------------------------------------------------------------------------
Adriana Angelotti, PhD
Politecnico di Milano
Dipartimento di Scienza e Tecnologie dell'Ambiente Costruito (Best)
v. Bonardi 3
20133 Milano
Italy
Ph    +39 02.2399.5183
Fax  +39 02.2399.5118
e-mail adriana.angelotti at polimi.it
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