<html xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<meta name=Generator content="Microsoft Word 11 (filtered medium)">
<style>
<!--
/* Font Definitions */
@font-face
{font-family:ISOCPEUR;
panose-1:2 11 6 4 2 2 2 2 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman";}
a:link, span.MsoHyperlink
{color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{color:#606420;
text-decoration:underline;}
p
{mso-margin-top-alt:auto;
margin-right:0cm;
mso-margin-bottom-alt:auto;
margin-left:0cm;
font-size:12.0pt;
font-family:"Times New Roman";}
span.EmailStyle18
{mso-style-type:personal;
font-family:ISOCPEUR;
color:windowtext;
font-weight:normal;
font-style:normal;
text-decoration:none none;}
span.EmailStyle19
{mso-style-type:personal-reply;
font-family:ISOCPEUR;
color:blue;
font-weight:normal;
font-style:normal;
text-decoration:none none;}
@page Section1
{size:612.0pt 792.0pt;
margin:72.0pt 90.0pt 72.0pt 90.0pt;}
div.Section1
{page:Section1;}
-->
</style>
</head>
<body lang=EN-US link=blue vlink="#606420">
<div class=Section1>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-GB style='font-size:
9.0pt;font-family:Arial'>Dear Trnsys group,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-GB style='font-size:
9.0pt;font-family:Arial'>I am trying to model a Solar hot water system using
vacuum tubes with concentrator (I am using Schott vacuum tubes). I only have
the instant efficiency test (quadratic equation) from the manufacturer. I am
not sure if I should use TYPE 74 (CPC collector) or TYPE 71 (Vacuum Tube),
because I don’t know if Type 71 –or the instant efficiency
equation- will take account of the “concentration effect” into the
absorber. Does anyone have any recommendations on what to do? Many thanks<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face=Arial><span lang=EN-GB style='font-size:
9.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<div>
<p><font size=1 face=Arial><span style='font-size:9.0pt;font-family:Arial'>Xavi
Ariņo<o:p></o:p></span></font></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span lang=EN-GB
style='font-size:12.0pt'><o:p> </o:p></span></font></p>
</div>
</body>
</html>