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Raffaele,<br>
I am afraid that we are no longer actively supporting TRNSYS 16.
However, I looked at your project quickly. The data file for your
chiller shows that at low part load ratios, it has some cooling
capacity but does not require any input energy. The first line of
performance data in the file is:<br>
<br>
0.7237 0.0000<br>
<br>
which indicates that at the following conditions:<br>
<br>
fraction of design load = 0.<br>
chilled water setpoint = 5.5C<br>
entering cooling water temperature = 24C<br>
inlet hot water temperature = 75C<br>
<br>
the device can produce 72.4% of its rated capacity and requires no
input energy to do so. I would imagine that the reason the chiller
is giving you a zero COP is that it is operating at low load
conditions and the model is showing that it needs no input power in
order to do so. Probably the machine cannot operate at part load
less than about 20%, in which case the capacity ratio as well as the
fraction of design energy input ratio should be zero.<br>
<br>
As for the auxiliary heater problem, I am less sure as to the cause
of the problem. However, I did notice that the tank in that loop is
7000L, that the pump has a flow rate of 26000L/h and that your time
step is 1 hour. That would mean that the pump (which is always on
according to your controls) turns over the entire volume of the tank
almost 4 times per timestep. Actually I am a bit surprised that the
simulation runs at all! In order for systems to be numerically
stable, there must be at least enough volume in flow loops to store
at least 1 time step of flow. Also keep in mind that a system can
only make one control decision per timestep; a one hour timestep is
very long. I would recommend something on the order of 1 or 5
minutes.<br>
<br>
Best,<br>
David<br>
<br>
<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 10/16/2012 16:56, Ralph Lanegan
wrote:<br>
</div>
<blockquote
cite="mid:CA+25tXGb=cTG000VCVZD3ZJ=P-u73aMYteVMpnyoksuRto232Q@mail.gmail.com"
type="cite">Dear TRNSYS users,<br>
<br>
as far as I can see many of you have worked on Solar Cooling
models with an absorption chiller.<br>
<br>
Attached you can find the one I've tried to build to cool my 900
sqm office (Yazaki SC-30 data file was created by me and cooling
tower file was derived from documentation).<br>
<br>
Now, the two problems I'm facing here are that absorption machine
does not start (COP always zero) and auxiliary heater stops
working at 4833 hrs<br>
<br>
Is there anyone available to give me support or hints to go ahead?<br>
<br>
Thanks in advance<br>
Raffaele<br>
<br>
<br>
<br>
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<br>
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<pre class="moz-signature" cols="72">--
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI 53703 USA
P:+1.608.274.2577
F:+1.608.278.1475
<a class="moz-txt-link-abbreviated" href="mailto:d.bradley@tess-inc.com">d.bradley@tess-inc.com</a>
<a class="moz-txt-link-freetext" href="http://www.tess-inc.com">http://www.tess-inc.com</a>
<a class="moz-txt-link-freetext" href="http://www.trnsys.com">http://www.trnsys.com</a></pre>
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