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<p>Julien,</p>
<p>In the TESS Solar Libraries add-on, our Type 538 is an evacuated tube model with all of the bells and whistles; detailed incidence angle modifiers, collector mass, controls for delivery of a specified temperature output etc. I use it every day and it works really well. We took the time a few years back to derive the F' function using the quadratic efficiency equation approach and I can tell you that it wasn't easy. If you'd like to see the details of the F' approach, the best reference is "Solar Engineering of Thermal Processes" by <span>Duffie</span> and Beckman. In this great solar book they derive the F' approach and apply it to linear efficiency equation collectors.</p>
<p>May I ask why you are trying to write your own evacuated tube model when both 71 and 538 handle most cases? </p>
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<p>Jeff</p>
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<pre>---<br />Jeff Thornton
President - TESS LLC
3 N. Pinckney Street, Suite 202, 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 05/13/2020 5:04 am, Julien Gambade via TRNSYS-users wrote:</p>
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<div>Dear Trnsys Users,</div>
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<div>I would like to program my Water-In-Glass Evacuated Tube Solar Collector. </div>
<div>My idea was to start from the existing Type71 but I am stuck because i can't understand how the 'Fprime_function' works. I searched online, on the Programmers Guide and in the TrnsysFunctions.f90 but still, I don't understand. </div>
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<div><!-- node type 8 -->Can anyone know any references to help me ?<!-- node type 8 --></div>
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<div>Moreover, someone might already program an Water-In-Glass ETC, i would be happy if you have any advise or program to share.</div>
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<div><!-- node type 8 -->Best regards,<!-- node type 8 --></div>
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<div>-- </div>
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<div><strong>Julien GAMBADE</strong><br /><strong>Doctorant</strong><br />Institut de Recherche Dupuy de Lôme (UMR CNRS 6027)<br />Centre de recherche Christian Huygens<br />Rue de Saint-Maudé - 56100 Lorient - France<br />julien.gambade@univ-ubs.fr<br /><a href="http://www.irdl.fr">www.irdl.fr</a></div>
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