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<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:12.0pt;font-family:"Times New Roman",serif;color:#0F5573;mso-fareast-language:EN-US">Hi Daniel,
<o:p></o:p></span></a></p>
<p class="MsoNormal"><span style="mso-bookmark:_MailEndCompose"><span style="font-size:12.0pt;font-family:"Times New Roman",serif;color:#0F5573;mso-fareast-language:EN-US"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_MailEndCompose"><span lang="EN-US" style="font-size:12.0pt;font-family:"Times New Roman",serif;color:#0F5573;mso-fareast-language:EN-US">Please check if the mass flow of the AHU is correct. 130 kg/s is huge for
this size of the zones, or do you mean 130 kg/h?<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_MailEndCompose"><span lang="EN-US" style="font-size:12.0pt;font-family:"Times New Roman",serif;color:#0F5573;mso-fareast-language:EN-US"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_MailEndCompose"><span lang="EN-US" style="font-size:12.0pt;font-family:"Times New Roman",serif;color:#0F5573;mso-fareast-language:EN-US">Regards,<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:_MailEndCompose"><span lang="EN-US" style="font-size:12.0pt;font-family:"Times New Roman",serif;color:#0F5573;mso-fareast-language:EN-US">Matthias Frechen<o:p></o:p></span></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> TRNSYS-users [mailto:trnsys-users-bounces@lists.onebuilding.org]
<b>On Behalf Of </b>Weber Daniel via TRNSYS-users<br>
<b>Sent:</b> Mittwoch, 29. August 2018 11:27<br>
<b>To:</b> trnsys-users@lists.onebuilding.org<br>
<b>Cc:</b> Weber Daniel <webedani@student.ethz.ch><br>
<b>Subject:</b> [External] [TRNSYS-users] Humidity Calculation Error<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black">Dear TRNSYS users,
<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black">I am modelling a 3D multizone building with Type 56. I have two small zones (volume ~15m^3) which have high coupling air flows to adjacent zones, since they have
each one return duct in them. My AHU goes up to 130kg/s and if it's in that state I get the following error:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black;background:white">Small internal timesteps (<0.1% of simulation timestep) used for humidity calculations due to large coupling air flows between zones!</span><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black">I read that these calculations are affected by the zone volume, its total airflow to other zones and the size of the timestep. Therefore I artificially increased
the volume, decreased the airflow of the AHU and decreased the timestep and the error disappeared.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black">But now my model is not as it should be, is there any other way to get rid of this error without changing zone volumes and coupling air flows?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black">Thank you for your help and best regards,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black">Daniel Weber<o:p></o:p></span></p>
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