[TRNSYS-users] Type60t and convergence problems

[Matteo DF]

Thanks for the replies...

My timestep is 15 minutes, I need to simulate 1 to 10 years so if i use a
littler time step the calculation time raises too much... I'll try
re-ordering the components and make sure there are no very small flowrates,
in fact the flowrate out from the heat pump is calculated from the thermal
request of the building which varies every hour. In fact if this thermal
request is approaching to zero the flowrate becomes very small.

I'll check if my university has bought the TESS libraries which contains
type534...

Thanks again,
Matteo.

2010/1/15 Michaël Kummert <michael.kummert at gmail.com>

> 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.
>
> --
> La scoperta è vedere ciò che tutti hanno sempre visto e
> pensare ciò che nessuno ha mai pensato.
> (Albert Szent-Gyorgyi, scopritore della vitamina C e premio Nobel)
>
>


-- 
La scoperta è vedere ciò che tutti hanno sempre visto e
pensare ciò che nessuno ha mai pensato.
(Albert Szent-Gyorgyi, scopritore della vitamina C e premio Nobel)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/trnsys-users-onebuilding.org/attachments/20100117/d39e328b/attachment-0005.htm>