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<p>Shahen,</p>
<p>I suggest you use the TRACE command and check to see what the controller is producing for a signal through all iterations of the timestep. It's very possible that the simulation is not converging and you are seeing the result of that non-convergence. Make sure you are using a small timestep, have pipes for capacitance, etc. We control towers all the time but use the tempering valve controller module in the TESS HVAC Library and not an external controller.</p>
<p> </p>
<p>Jeff</p>
<p> </p>
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<pre>---<br />Jeff Thornton
President - TESS LLC
22 N. Carroll Street, Madison WI USA 53703
Office: (608) 274-2577 Fax: (608) 278-1475
www.tess-inc.com
E-Mail: thornton@tess-inc.com
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<p>On 08/19/2014 8:43 am, Shahen Fakhraldin wrote:</p>
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<div id="yiv9073490056yui_3_16_0_6_1408026953904_4" style="color: #000000; font-family: verdana, helvetica, sans-serif; font-size: 10pt;"><span id="yiv9073490056yui_3_16_0_6_1408026953904_15">Dear TRNSYS users,</span></div>
<div id="yiv9073490056yui_3_16_0_6_1408026953904_4" style="color: #000000; font-size: 13.600000381469727px; font-style: normal; background-color: transparent;"><span id="yiv9073490056yui_3_16_0_6_1408026953904_21"> </span></div>
<div id="yiv9073490056yui_3_16_0_6_1408026953904_4" style="font-family: verdana, helvetica, sans-serif; font-size: 10pt; background-color: transparent;"><span id="yiv9073490056yui_3_16_0_6_1408026953904_26" style="color: #000000; font-family: verdana, helvetica, sans-serif; font-size: 13.600000381469727px; font-style: normal;">I am trying to control a cooling tower of absorption chiller by </span><span id="yiv9073490056yui_3_16_0_1_1408026953904_2997" style="background-color: transparent;">using a three-way valve (type 11f) to mix between the returned water from the chiller and the water coming from the cooling tower (type 51b). </span></div>
<div id="yiv9073490056yui_3_16_0_6_1408026953904_4" style="color: #000000; font-family: verdana, helvetica, sans-serif; font-size: 13.600000381469727px; font-style: normal; background-color: transparent;"><span style="background-color: transparent;"> </span></div>
<div id="yiv9073490056yui_3_16_0_6_1408026953904_4" style="color: #000000; font-family: verdana, helvetica, sans-serif; font-size: 13.600000381469727px; font-style: normal; background-color: transparent;"><span id="yiv9073490056yui_3_16_0_6_1408026953904_43" style="background-color: transparent;">I assumed the range of temperature of mixing 28 - 33 C</span><span id="yiv9073490056yui_3_16_0_1_1408026953904_3211" style="font-size: 10pt; background-color: transparent;"> (over 33 C the flow completely will be through the cooling tower), and </span><span id="yiv9073490056yui_3_16_0_1_1408093370808_12173" style="font-size: 10pt; background-color: transparent;">I am using (W-</span><span style="font-size: 10pt; background-color: transparent;"><span id="yiv90734900567994e2fc-7847-4602-a716-5a20b00a7808">interpreter</span></span><span id="yiv9073490056yui_3_16_0_1_1408093370808_12174" style="font-size: 10pt; background-color: transparent;">) to produce the mixer (diverter) signal.</span></div>
<div id="yiv9073490056yui_3_16_0_6_1408026953904_4" style="color: #000000; font-family: verdana, helvetica, sans-serif; font-size: 10pt; font-style: normal; background-color: transparent;"> </div>
<div id="yiv9073490056yui_3_16_0_6_1408026953904_4" style="color: #000000; font-family: verdana, helvetica, sans-serif; font-size: 10pt; font-style: normal; background-color: transparent;">I am getting strange results where <span style="font-size: 10pt;">the inlet mass to the chiller (that comes from the cooling tower subsystem) </span><span style="font-size: 10pt; background-color: transparent;">is not equal to </span><span style="font-size: 10pt;">the inlet mass of the cooling tower subsystem (that comes from the chiller), even these mass rates exceeded the rated flow rate of the pump of cooling tower subsystem (type 114). </span><span style="font-size: 10pt; background-color: transparent;">Whereas </span><span style="font-size: 10pt; background-color: transparent;">if the diverter signal is fixed (from 0 to 1.0) I do not face this error</span></div>
<div id="yiv9073490056yui_3_16_0_6_1408026953904_4" style="color: #000000; font-family: verdana, helvetica, sans-serif; font-size: 10pt; font-style: normal; background-color: transparent;"> </div>
<div id="yiv9073490056yui_3_16_0_6_1408026953904_4" style="color: #000000; font-family: verdana, helvetica, sans-serif; font-size: 10pt; font-style: normal; background-color: transparent;">Did anyone try controlling a cooling tower in TRNSYS?</div>
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<div id="yiv9073490056yui_3_16_0_6_1408026953904_4" style="background-color: transparent;">All kinds of help are very much appreciated.</div>
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<div id="yiv9073490056yui_3_16_0_6_1408026953904_4" style="color: #000000; font-family: verdana, helvetica, sans-serif; font-size: 13.600000381469727px; font-style: normal; background-color: transparent;"><span id="yiv9073490056yui_3_16_0_6_1408026953904_36">Kind regards,</span></div>
<div id="yiv9073490056yui_3_16_0_6_1408026953904_4" style="color: #000000; font-size: 13.600000381469727px; font-style: normal; background-color: transparent;"><span id="yiv9073490056yui_3_16_0_6_1408093370808_64">Shahen</span></div>
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