<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>If you don't have measured data to tune the model against, use a value of 1.0 for both. From years of calibrating the model against real data, I would also suggest a value between 0.4 and 0.6 for the Rayleigh multiplier and a value of 0.25 for the Rayleigh exponent.</div><div><br></div><div>Jeff Thornton (Author of Type534)<br><br>Sent from my iPhone</div><div><br>On Mar 27, 2015, at 6:21 PM, Martin Berov <<a href="mailto:martber88@gmail.com">martber88@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr">Dear David,<div><br></div><div>Thank you for the suggestion. I'll use Type 534 - coiled, but can you suggest me which are usually used values for the "geometry factor for natural convection" and "geometry exponent for natural convection".</div><div><br></div><div>Best Regards</div><div>Martin</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Mar 27, 2015 at 10:45 PM, David BRADLEY <span dir="ltr"><<a href="mailto:d.bradley@tess-inc.com" target="_blank">d.bradley@tess-inc.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
Martin,<br>
I would highly recommend that if at all possible you use Type534
from the TESS Storage Tank library in place of Type60. Type534 has
an internal heat exchanger model that is far more robust than the
one built in to Type60.<br>
Kind regards,<br>
David<div><div class="h5"><br>
<br>
<br>
<div>On 3/27/2015 3:11 PM, Martin Berov
wrote:<br>
</div>
</div></div><blockquote type="cite"><div><div class="h5">
<div dir="ltr">Dear TRNSYS users,
<div><br>
</div>
<div>I'm trying to analyse the influence of the heat exchanger
area on the solar fraction and collector efficiency.</div>
<div><br>
</div>
<div>I'm using storage tank Type 60c with internal HX. Although
I change the area and the length(keeping the outside diameter
constant) I always get same results for the monthly solar
fraction and efficiency - like there is no influence.</div>
<div><br>
</div>
<div>What could be the reason for this? </div>
<div><br>
</div>
<div>Best regards</div>
<div>Martin</div>
</div>
<br>
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***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI 53703 USA
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