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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi Jeff,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thanks for your quick reply. I checked the connections and flow rates and they all seem to be ok. On the hot side I have a type 3b variable speed pump, on the
cold side a Type 3d single speed pump, both of which have the same maximum flow rates. And this particular flow rate I used as parameter 4 of Type 512 “Rated flow rate of hot side”. I also connected the 6<sup>th</sup> output of type 512 to the control signal
of the variable pump on the hot side of the exchanger..<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I still get this mass balance problem. Any ideas what is going wrong?<br>
<br>
Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Ciarán<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> trnsys-users-bounces@cae.wisc.edu [mailto:trnsys-users-bounces@cae.wisc.edu]
<b>On Behalf Of </b>Jeff Thornton<br>
<b>Sent:</b> 28. marraskuuta 2012 19:10<br>
<b>To:</b> trnsys-users@cae.wisc.edu<br>
<b>Subject:</b> Re: [TRNSYS-users] Type 512 (TESS): Mass balance warning message<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p><I am running my simulation with a type 512 heat exchanger and I get the following warning message (no convergence errors, just warnings) at the end of my simulation (time step: 0.1 hour):><o:p></o:p></p>
<p>Type 512 has internal controls to vary the speed of the hot-side flow rate through the heat exchanger. I'm guessing that you're hooking up a pump to this heat exchanger and the flow rate into the HX is not the flow rate out of the HX - as 512 is setting
the flow rate. The best way to use 512 is to use a variable speed pump model and make sure the maximum flow rate parameter for both the pump and HX models are identical. Then put the pump either upstream or downstream of the HX and connect the 6th output
of the heat exchanger model to the control signal for the pump - so that they both produce the same flow rate.<o:p></o:p></p>
<p> <o:p></o:p></p>
<p>Jeff<o:p></o:p></p>
<p> <o:p></o:p></p>
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<pre>---<o:p></o:p></pre>
<p>Jeff Thornton<o:p></o:p></p>
<p><em>President - TESS LLC</em><o:p></o:p></p>
<p><em>22 N. Carroll Street, Madison WI USA 53703</em><o:p></o:p></p>
<p><em>Office: (608) 274-2577 Fax: (608) 278-1475</em><o:p></o:p></p>
<p><em><a href="http://www.tess-inc.com"><span style="font-style:normal">www.tess-inc.com</span></a></em><o:p></o:p></p>
<p><em>E-Mail: <a href="mailto:thornton@tess-inc.com"><span style="font-style:normal">thornton@tess-inc.com</span></a></em><o:p></o:p></p>
<p> <o:p></o:p></p>
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<p>On 11/28/2012 6:11 am, Flynn Ciaran wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hello,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I am running my simulation with a type 512 heat exchanger and I get the following warning message (no convergence errors, just warnings) at the end of my simulation (time step:
0.1 hour):<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">*** Warning at time : 39384.000000<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> Generated by Unit : 45<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> Generated by Type : 512<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> Message : Heat exchanger mass balance failed during 112810 time steps. Please check the connections.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I do not understand what could be the reason for this. I have gone through my connections and they all seem fine (I do not get this problem with heat exchanger type 91).<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Thanks for your help,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Ciarán<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><em><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">----------------------------------------</span></em><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><em><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">Ciarán Flynn</span></em><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><em><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">Research Scientist</span></em><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><em><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black"> </span></em><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><em><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">Aalto University</span></em><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><em><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">Department of Energy Technology</span></em><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><em><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">P.O.Box 14100, 00076 Aalto</span></em><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><em><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">Otakaari 4, 02150 ESPOO</span></em><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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