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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Matteo,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I use type 534 and have convergence
issues. The first step I use when debugging tank convergence is to set the tank
to instantly correct thermal inversions.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Another technique is to set your pump to
speed up slowly so that the system does not see the thermal shock. Both of
these limit the model’s validity, but each is valid for debugging purposes. Type60
has a destratification conductivity parameter. Sounds like it might possibly help
you debug. Also increasing iterations will sometimes allow the model to find a
solution although in cases of high relative flow rates or large temperature
difference the thermal shock might be too large to allow convergence at all.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Solar can be especially problematic due to
the temperatures of air-exposed and ground-exposed liquid that enters the tank
during winter startup conditions. Adding pipe to the system can help, but
sometimes it makes matters worse.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I hope some of this advise is useful.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Good Luck, <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>John Bisgrove</span></font><font
color=navy><span style='color:navy'><o:p></o:p></span></font></p>
<p class=MsoNormal><em><i><font size=2 color=navy face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:navy'>Earth Sensitive Solutions</span></font></i></em><font
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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>(315)253-3779</span></font><o:p></o:p></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> Matteo DF
[mailto:deframat@gmail.com] <br>
<b><span style='font-weight:bold'>Sent:</span></b> Sunday, January 17, 2010
4:13 AM<br>
<b><span style='font-weight:bold'>To:</span></b> trnsys-users@cae.wisc.edu<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [TRNSYS-users]
Type60t and convergence problems</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>Thanks for the replies...<br>
<br>
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.<br>
<br>
I'll check if my university has bought the TESS libraries which contains
type534...<br>
<br>
Thanks again,<br>
Matteo.<o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>2010/1/15 Michaël Kummert <<a href="mailto:michael.kummert@gmail.com">michael.kummert@gmail.com</a>><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Matteo,<br>
<br>
Sometimes re-ordering the components helps (“component order” tab in the<br>
control cards). Since you have already reduced the time step and added pipes<br>
to the system that’s the only thing I can really think of. You could also<br>
check the flowrate / heat transfer rate out of the heat pump, see if they<br>
make sense. If you get extreme values they might be causing problems in the<br>
heat exchanger model within the tank. Sometimes very small (but non-zero)<br>
flowrates also cause problems.<br>
This being said, Type 60 is one of these very old components that have not<br>
really aged gracefully in my opinion, and I avoid using it. Matt probably<br>
didn’t want to appear as a salesman for the TESS libraries, but I would<br>
recommend that you give a try to the tank model (Type534) in the TESS<br>
libraries if you can get access to them. It is easier to use and far more<br>
robust than Type 60. Of course you can still have convergence problems in<br>
the TRNSYS solver with that component, but at least you can trust the<br>
results when TRNSYS converges...<br>
Good luck,<br>
<br>
Michaël<br>
<br>
____________________________<br>
Michaël Kummert<br>
École Polytechnique Montréal<br>
<br>
<br>
<br>
From: Matteo DF [mailto:<a href="mailto:deframat@gmail.com">deframat@gmail.com</a>]<br>
Sent: January 14, 2010 06:06<br>
To: <a href="mailto:trnsys-users@cae.wisc.edu">trnsys-users@cae.wisc.edu</a><o:p></o:p></span></font></p>
<div>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>Subject: [TRNSYS-users]
Type60t and convergence problems<o:p></o:p></span></font></p>
</div>
<div>
<div>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>Hi everybody,<br>
<br>
I'm developing a model which simulates a solar assisted ground source heat<br>
pump. In this model I'm using 3 type60t tanks, one for domestic hot water,<br>
one for the ground heat exchangers (just before the heat pump) and another<br>
one is used for building heating.<br>
<br>
The problem is this last tank, in fact it contains 3 internal heat<br>
exchangers, one for heat coming from the hp, one from solar collectors and<br>
the last one for the auxiliary heating... The problem is that if I connect<br>
the HP to it I get convergence errors (which are not present if the hp isn't<br>
connected...). I checked every parameter, I've modified the tollerance for<br>
convergence from 0.001 to 0.01 and placed some type31 tubes in every section<br>
which convoys water to the tank... But the problem persists...<br>
<br>
How do I solve these problems? Isn't there a simpler tank which I can use<br>
that have the possibility to include at least 3 heat exchangers?<br>
<br>
Thanks!<br>
Matteo.<br>
<br>
--<br>
La scoperta è vedere ciò che tutti hanno sempre visto e<br>
pensare ciò che nessuno ha mai pensato.<br>
(Albert Szent-Gyorgyi, scopritore della vitamina C e premio Nobel)<o:p></o:p></span></font></p>
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<br clear=all>
<br>
-- <br>
La scoperta è vedere ciò che tutti hanno sempre visto e<br>
pensare ciò che nessuno ha mai pensato.<br>
(Albert Szent-Gyorgyi, scopritore della vitamina C e premio Nobel)<o:p></o:p></span></font></p>
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