<html><body bgcolor="#FFFFFF"><div>Good point about the turbulant flow, David. Glad to see someone still knows how to use there Fluid and Heat Transfer mechanics knowledge.<br><br>Sent from my iPhone</div><div><br>On 25.06.2012, at 21:45, David BRADLEY <<a href="mailto:d.bradley@tess-inc.com">d.bradley@tess-inc.com</a>> wrote:<br><br></div><div></div><blockquote type="cite"><div>
Camilo,<br>
I am not familiar with the table that is mentioned. The
documentation notes that values for Kair0 are typically between 7
and 11 kJ/h.K.m2 and Kair1 are between 14 and 18 (kJ/h.m2)/K/(m/s).
What I have typically done is to use some basic heat transfer
equations to calculate the Nusselt number for a few different flow
rates through the ducts as a function of the Reynolds and Prandtl
numbers. From the Nusselt number, you can then get the inside
convection coefficient and fit the values to arrive at Kair0 and
Kair1. I think my method over predicts the inside convection
coefficient but I haven't found a better way to do it<br>
<br>
One critical thing about earth tubes is to keep the flow turbulent.
Without knowing what kind of input changes you made in your
simulation between the cases that do and do not show total energy
differences across the earth duct it is hard to guess what might be
happening.<br>
Best,<br>
David<br>
<br>
<br>
On 6/24/2012 01:38, Camilo Arias wrote:
<blockquote cite="mid:1340519910.46570.YahooMailNeo@web114706.mail.gq1.yahoo.com" type="cite">
<div style="color:#000; background-color:#fff; font-family:arial,
helvetica, sans-serif;font-size:10pt">
<div><font face="arial, helvetica, sans-serif" size="2">Hi, i´m
working now with the type 460, in the FAQ file sended by
transsolar, said abaout a table to chose the Kair0 and Kair1
based in the diameter of the tube, i write to trnsssolar but
to now an not have a answare, maybe you have this
information, also, i make some probes share the result the
total energy (latent and sensible) with
a psychometric entalphy difference by the same flow mass
rate, the result are the same in the most parts, but for
some ones show some differences, do you know the reason of
this?.</font></div>
<div style="font-family: arial, helvetica, sans-serif;
font-size: 10pt; "><br>
</div>
<div style="font-family: arial, helvetica, sans-serif;
font-size: 10pt; ">Thanks</div>
<div style="font-family: arial, helvetica, sans-serif;
font-size: 10pt; "><br>
</div>
<div style="font-family: arial, helvetica, sans-serif;
font-size: 10pt; ">Camilo Arias </div>
</div>
<br>
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<br>
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David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
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