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Hsein,<br>
We faced a similar situation in a project a few years ago. We
investigated a number of possible solutions because what TRNSYS is
showing you is a real world potential problem in systems such as
yours. One thing we looked at was to put a buffer tank onto the
source loop. When the electrical load exceeded the immediate cooling
demand we were able to allow the buffer tank temperature to rise a
little bit. When the electrical load dropped off then we were able
to use some of the energy in the buffer to continue running the
absorption chillers. If the tank temperature dropped off too much
for the absorption chillers to operate then we investigated reliance
on traditional electric chillers. We also investigated the option of
running the generators so that if the electrical load dropped low
enough that the absorption chiller could not run then we would
overproduce electricity and send it back into the utility's electric
grid.<br>
kind regards,<br>
David<br>
<br>
<br>
<div class="moz-cite-prefix">On 02/10/2016 16:49, Hsein Moussawi
wrote:<br>
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<p style="font-family: Calibri, Arial, Helvetica, sans-serif;
font-size: 16px;">Hi there,</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif;
font-size: 16px;">Sorry for the mistake I mentioned in the
previous email.</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif;
font-size: 16px;">In fact, I can control the flow rate to the
evaporator by installing a storage (buffer) tank and this is
what I already did.</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif;
font-size: 16px;">The real problem behind the negative values
is the low flow rate to the generator and not the evaporator.
That's what I can't control since the generator is driven by
exhaust gases from certain prime mover which in turn depends
on the electrical load of the building (that I can't change).</p>
<p style="font-family: Calibri, Arial, Helvetica, sans-serif;
font-size: 16px;">Sorry and Thanks...again!</p>
<br>
<br>
<br>
<div style="color: rgb(0, 0, 0);">
<hr tabindex="-1" style="display:inline-block; width:98%">
<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt"
color="#000000" face="Calibri, sans-serif"><b>From:</b>
David BRADLEY <a class="moz-txt-link-rfc2396E" href="mailto:d.bradley@tess-inc.com"><d.bradley@tess-inc.com></a><br>
<b>Sent:</b> Thursday, February 11, 2016 12:07 AM<br>
<b>To:</b> TRNSYS users mailing list at OneBuilding.org;
<a class="moz-txt-link-abbreviated" href="mailto:hsein_moussawi@hotmail.com">hsein_moussawi@hotmail.com</a><br>
<b>Subject:</b> Re: [TRNSYS-users] Absorption chiller</font>
<div> </div>
</div>
<div>Hsein,<br>
This would be a problem in a real system as well, not just
in simulation. You need to isolate the load flow from the
source flow by using either a primary/secondary pumping
scheme or by putting a buffer tank between the load loop and
the source loop.<br>
kind regards,<br>
David<br>
<br>
<br>
<div class="moz-cite-prefix">On 02/10/2016 15:38, Hsein
Moussawi wrote:<br>
</div>
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<div id="divtagdefaultwrapper" style="font-size:12pt;
color:#000000; background-color:#FFFFFF;
font-family:Calibri,Arial,Helvetica,sans-serif">
<p>Hi angel,</p>
<p>Yes I know how it works and the negative
values mainly appear when the flow rate to the
evaporator is low. However in the system I am
simulating, I can't control this flow rate, it is
imposed by other components (cooling load from
building). So do you have other suggestions?</p>
<p>Thanks for the fast reply.</p>
<p>Regards.</p>
<br>
<br>
<div style="color:rgb(0,0,0)">
<hr tabindex="-1" style="display:inline-block;
width:98%">
<div id="divRplyFwdMsg" dir="ltr"><font
style="font-size:11pt" color="#000000"
face="Calibri, sans-serif"><b>From:</b> Angel
Carrera
<a moz-do-not-send="true"
class="moz-txt-link-rfc2396E"
href="mailto:angel.carrera@aiguasol.coop"><angel.carrera@aiguasol.coop></a><br>
<b>Sent:</b> Wednesday, February 10, 2016 9:28 PM<br>
<b>To:</b> TRNSYS users mailing list at
OneBuilding. org<br>
<b>Subject:</b> Re: [TRNSYS-users] Absorption
chiller</font>
<div> </div>
</div>
<div>
<p dir="ltr"><br>
Hi,</p>
<p dir="ltr">I giess that the flowrate you are
giving as an input is too low related to the power
requirement at the evaporator.<br>
I suggest you to read the descripción of the type
to understand how it is working, regards</p>
<p dir="ltr">Angel</p>
<div class="gmail_quote">El 10/2/2016 20:14, "Hsein
Moussawi" <<a moz-do-not-send="true"
href="mailto:hsein_moussawi@hotmail.com">hsein_moussawi@hotmail.com</a>>
escribió:<br type="attribution">
<blockquote class="gmail_quote" style="margin:0 0
0 .8ex; border-left:1px #ccc solid;
padding-left:1ex">
<div dir="ltr">
<div style="font-size:12pt; color:#000000;
background-color:#ffffff;
font-family:Calibri,Arial,Helvetica,sans-serif">
<p>Hello there,</p>
<p>I am using an exhaust fired absorption
chiller in a certain system. After
simulation the temperature of the hot
fluid exiting the chiller is observed to
be negative in many instances. This is
impossible in reality. I am wondering if
anyone faced a similar problem!?</p>
<p>My question is: </p>
<p>Is there a way by which I can limit the
output of a component to a certain point??
(e.g. outlet temperature of chiller to
ambient temperature)</p>
<p>Thanks in advance TRNSYS community,</p>
<p>Best regards.</p>
</div>
</div>
<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 moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:d.bradley@tess-inc.com">d.bradley@tess-inc.com</a>
<a moz-do-not-send="true" class="moz-txt-link-freetext" href="http://www.tess-inc.com">http://www.tess-inc.com</a>
<a moz-do-not-send="true" class="moz-txt-link-freetext" href="http://www.trnsys.com">http://www.trnsys.com</a></pre>
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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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