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<p class="MsoNormal"><span style="color:windowtext;mso-fareast-language:EN-US">Dear Loïc<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:windowtext;mso-fareast-language:EN-US">I have to confess that this is a little confusing.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:windowtext;mso-fareast-language:EN-US">I would have loved to remove the surface category “internal” completely. However, due to backwards compatibility it remained.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:windowtext;mso-fareast-language:EN-US">I recommend to use
</span><span lang="EN-US">category 'boundary' and the boundary condition 'identical' because there it is more clear what is calculated.</span><span lang="EN-US" style="color:windowtext;mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:windowtext;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:windowtext;mso-fareast-language:EN-US">Please find my comments below:<o:p></o:p></span></p>
<p><span lang="EN-US">I noticed that the first option implies to consider the total exposed surface (both sides) for the area parameter, unlike the second one. I guess that in (a) the middle of the wall is assumed adiabatic in order to model only a half wall
but with an area 2 times higher. If this is correct, it is implicitly assumed that the internal wall composition is symetric. By the way, I found that the wall balance is not null otherwise.<o:p></o:p></span></p>
<p><span lang="EN-US">Is the (a) modelling really only concern symetric composition?<br>
</span><span lang="EN-US" style="color:#0070C0">=> Yes, for the option “internal” the composition has to be internal</span><span lang="EN-US"><o:p></o:p></span></p>
<p><span lang="EN-US">Nonetheless, when I compare (a) with a 2*S area and (b) with a S area, for a symetric composition, the results are not exactly the same. I succeed having same results by setting the composition of (a) with only the half of it (from a face
to the middle).<o:p></o:p></span></p>
<p><span lang="EN-US" style="color:#0070C0">=> For having (a) and (b) giving similar results you have to use for (b) the same exposed area to the airnode/zone as for (a) (area =2*S).<br>
Otherwise the airnode/zone doesn’t have “access” the same amount of thermal mass. This results in different heat fluxes to the inner surface
<br>
node. </span><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">So, the (a) modelling need half composition?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#0070C0">=> No, (b) requires double area (see above).
<br>
Have in mind that “Internal” means that both sides of the construction are facing towards the zone. You have to define the total construction<br>
for having the correct mass. The program divides the construction itself.<br>
<br>
<o:p></o:p></span></p>
<p><span lang="EN-US">Regards,<o:p></o:p></span></p>
<p><span lang="EN-US">Marion<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:#0070C0"> </span><span lang="EN-US" style="color:windowtext;mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="color:windowtext;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="DE-CH" style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#005A00;mso-fareast-language:DE-CH">Dipl.-Ing. Marion Hiller </span></b><b><span lang="DE-CH" style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#009900;mso-fareast-language:DE-CH"><br>
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<p class="MsoNormal"><b><span lang="DE-CH" style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#007000;mso-fareast-language:DE-CH">t:
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<p class="MsoNormal"><b><span lang="DE-CH" style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#0070C0;mso-fareast-language:DE-CH"><a href="http://www.transsolar.com/" target="_blank"><span style="color:#0070C0">www.transsolar.com/</span></a></span></b><b><span lang="DE-CH" style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#005A00;mso-fareast-language:DE-CH"> <br>
<br>
</span></b><b><span lang="DE-CH" style="font-size:7.5pt;font-family:"Arial",sans-serif;color:windowtext;mso-fareast-language:DE-CH">KlimaEngineering - Technologien für energieeffizientes Bauen und Nutzerkomfort in Gebäuden </span></b><b><span lang="DE-CH" style="font-size:7.5pt;font-family:"Arial",sans-serif;color:#005A00;mso-fareast-language:DE-CH"><br>
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<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span lang="DE-CH" style="font-size:7.5pt;font-family:"Arial",sans-serif;color:windowtext;mso-fareast-language:DE-CH">Amtsgericht Stuttgart - HRB 23347</span></b><b><span style="font-size:7.5pt;font-family:"Arial",sans-serif;color:windowtext;mso-fareast-language:DE-CH">
/ Steuernummer: 99073/00911 / USt-IdNr.: DE 152272639</span></b><b><span lang="DE-CH" style="font-size:7.5pt;font-family:"Arial",sans-serif;color:windowtext;mso-fareast-language:DE-CH"><br>
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<p class="MsoNormal"><b><span style="color:windowtext">Von:</span></b><span style="color:windowtext"> TRNSYS-users <trnsys-users-bounces@lists.onebuilding.org>
<b>Im Auftrag von </b>Loïc Frayssinet via TRNSYS-users<br>
<b>Gesendet:</b> Donnerstag, 21. Februar 2019 15:35<br>
<b>An:</b> trnsys-users@lists.onebuilding.org<br>
<b>Cc:</b> Loïc Frayssinet <frayssinet@enertech.fr><br>
<b>Betreff:</b> [TRNSYS-users] Internal wall modelling<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p>Dear all,<o:p></o:p></p>
<p>I was wondering if it is similar to model an internal wall as a wall :<o:p></o:p></p>
<p>(a) with the category 'internal' or<br>
(b) with the category 'boundary' and the boundary condition 'identical'<o:p></o:p></p>
<p>I noticed that the first option implies to consider the total exposed surface (both sides) for the area parameter, unlike the second one. I guess that in (a) the middle of the wall is assumed adiabatic in order to model only a half wall but with an area
2 times higher. If this is correct, it is implicitly assumed that the internal wall composition is symetric. By the way, I found that the wall balance is not null otherwise.<o:p></o:p></p>
<p>Is the (a) modelling really only concern symetric composition?<o:p></o:p></p>
<p>Nonetheless, when I compare (a) with a 2*S area and (b) with a S area, for a symetric composition, the results are not exactly the same. I succeed having same results by setting the composition of (a) with only the half of it (from a face to the middle).<o:p></o:p></p>
<p>So, the (a) modelling need half composition? If yes, why non-symetric compositions causes balance divergences?<o:p></o:p></p>
<p>Regards,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">-- <br>
<b>Loïc FRAYSSINET </b><o:p></o:p></p>
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