[TRNSYS-users] Type60t and convergence problems

[Michaël Kummert]

Matteo,

Sometimes re-ordering the components helps (“component order” tab in the
control cards). Since you have already reduced the time step and added pipes
to the system that’s the only thing I can really think of. You could also
check the flowrate / heat transfer rate out of the heat pump, see if they
make sense. If you get extreme values they might be causing problems in the
heat exchanger model within the tank. Sometimes very small  (but non-zero)
flowrates also cause problems.
This being said, Type 60 is one of these very old components that have not
really aged gracefully in my opinion, and I avoid using it. Matt probably
didn’t want to appear as a salesman for the TESS libraries, but I would
recommend that you give a try to the tank model (Type534) in the TESS
libraries if you can get access to them. It is easier to use and far more
robust than Type 60. Of course you can still have convergence problems in
the TRNSYS solver with that component, but at least you can trust the
results when TRNSYS converges...
Good luck,

Michaël 

____________________________
Michaël Kummert
École Polytechnique Montréal



From: Matteo DF [mailto:deframat at gmail.com] 
Sent: January 14, 2010 06:06
To: trnsys-users at cae.wisc.edu
Subject: [TRNSYS-users] Type60t and convergence problems

Hi everybody,

I'm developing a model which simulates a solar assisted ground source heat
pump. In this model I'm using 3 type60t tanks, one for domestic hot water,
one for the ground heat exchangers (just before the heat pump) and another
one is used for building heating. 

The problem is this last tank, in fact it contains 3 internal heat
exchangers, one for heat coming from the hp, one from solar collectors and
the last one for the auxiliary heating... The problem is that if I connect
the HP to it I get convergence errors (which are not present if the hp isn't
connected...). I checked every parameter, I've modified the tollerance for
convergence from 0.001 to 0.01 and placed some type31 tubes in every section
which convoys water to the tank... But the problem persists...

How do I solve these problems? Isn't there a simpler tank which I can use
that have the possibility to include at least 3 heat exchangers?

Thanks!
Matteo. 

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