<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
Zhe,<br>
The incidence angle modifiers (IAMs) that are described in
.\Examples\Data Files\Type71-EvacuatedTubeSolarCollector-IAMData.dat
and which are being used by Type71 are quite a lot different from
the IAMs that are described in .\Tess
Models\SampleCatalogData\Bi-Axial IAMs\Typical_EvacTube_IAM_2d.dat
and which are being used by Type538. I think that if you alter one
of the files to match the IAMs in the other, you will end up with a
much more similar result between the two.<br>
Kind regards,<br>
David<br>
<br>
<div class="moz-cite-prefix"><br>
On 10/23/2012 09:31, Zhe Li wrote:<br>
</div>
<blockquote cite="mid:00cd01cdb12b$22bbb750$683325f0$%25Li@dit.ie"
type="cite">
<meta http-equiv="Content-Type" content="text/html;
charset=ISO-8859-1">
<meta name="Generator" content="Microsoft Word 12 (filtered
medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
@font-face
{font-family:Consolas;
panose-1:2 11 6 9 2 2 4 3 2 4;}
@font-face
{font-family:"Times New Roman \, serif";
panose-1:0 0 0 0 0 0 0 0 0 0;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";
color:black;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
pre
{mso-style-priority:99;
mso-style-link:"HTML Preformatted Char";
margin:0cm;
margin-bottom:.0001pt;
font-size:10.0pt;
font-family:"Courier New";
color:black;}
p.MsoAcetate, li.MsoAcetate, div.MsoAcetate
{mso-style-priority:99;
mso-style-link:"Balloon Text Char";
margin:0cm;
margin-bottom:.0001pt;
font-size:8.0pt;
font-family:"Tahoma","sans-serif";
color:black;}
span.HTMLPreformattedChar
{mso-style-name:"HTML Preformatted Char";
mso-style-priority:99;
mso-style-link:"HTML Preformatted";
font-family:Consolas;
color:black;}
span.EmailStyle19
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:windowtext;}
span.EmailStyle20
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:#1F497D;}
span.EmailStyle21
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
span.BalloonTextChar
{mso-style-name:"Balloon Text Char";
mso-style-priority:99;
mso-style-link:"Balloon Text";
font-family:"Tahoma","sans-serif";
color:black;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 72.0pt 72.0pt 72.0pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
<div class="WordSection1">
<p class="MsoNormal"><span style="color:#1F497D">David,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Thank you very
much for your suggestion. I did put a water tank in between
the load loop and the heat pump. The result I am getting is
great. However, I remembered you mentioned that your company
is developing a multi-stage air-water heat pump component. I
think this is very applicable for my case. I am wondering if
this component has been finalised? If it is, would be
possible if I can obtain this component. As even though the
simulation result is very good, I am still not setting up
the system as identical as the actual system (the system I
want to set up) is. I may encounter some difficult questions
over the system set up in my final thesis defence. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I asked about
the mathematical description of Type941 air-water heat pump.
I think this is still in the writing stage. I am wondering
that when this mathematical description will be released,
would be possible if I can obtain a copy of this description
as soon as it is complete? This is very important for my PhD
thesis, it is not convincing without a full detailed maths
description in the thesis.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Please find
attached two examples of solar thermal systems using
identical parameters with collector type538 and type71. The
sum of Useful Energy Gain from type538 and type71 is
2669.41kWh and 1876.44kWh respectively. I don’t understand
why the results are significantly different. Hope you could
give me some advice and direction.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Thank you so
much for all your help. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Zhe Li <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"
lang="EN-US">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"
lang="EN-US"> David BRADLEY
[<a class="moz-txt-link-freetext" href="mailto:d.bradley@tess-inc.com">mailto:d.bradley@tess-inc.com</a>] <br>
<b>Sent:</b> 19 October 2012 19:26<br>
<b>To:</b> Zhe Li<br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:trnsys-users@cae.wisc.edu">trnsys-users@cae.wisc.edu</a><br>
<b>Subject:</b> Re: [TRNSYS-users] Air source heat pump
system validation<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">Zhe,<br>
This is a problem with actual single stage heat pumps, not
just a simulation problem. Single stage heat pumps cannot
really modulate their output power so under low load
conditions, they can overheat a fluid loop. One effective way
of solving the problem is to put a water tank in between the
load loop and the heat pump. It requires an additional pump
but then the load loop draws water from and returns water to
the tank. When the tank temperature drops, the heat pump loop
turns on and heats the tank back up again. Under low load
conditions, the load slowly draws the tank temperature down
and the heat pump stays off.<br>
<br>
I am not sure what the problem with Type538 might be. I'd be
interested if you could send me a project showing the
difference in result between the two.<br>
<br>
As for the collector capacitance, often collector
manufacturers will tell you the liquid volume of the
collector. You can calculate a capacitance from the volume and
from the specific heat of your working fluid. Without any
better knowledge, though, we use a value of about 10 kJ/m2 of
collector area. <br>
Best,<br>
David<br>
<br>
<o:p></o:p></p>
<div>
<p class="MsoNormal">On 10/18/2012 09:35, Zhe Li wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span style="color:#1F497D">David,</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Thank you
very much for your response a couple of days ago. I have
been considering your advice and trying to make some
changes in my simulation models. However, I have not been
successful. I did identify the major problem, as you have
explained, once the controller trigger the ON function,
the heat pump runs without limiting the useful energy
required for the thermal load, this results a massive
energy overproduced especially for summer months. I am
trying to write an equation to reduce the flowrate in
order to prevent energy been overly produced. The whole
validation I am carrying out against is a system without a
buffer tank, hence I will have to set up an air source
heat pump system without a buffer tank even though I
understand it is more accurate to do so. In your
experience, how would you do if you are in my situation? </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Also come
back to the solar thermal system. I remembered that you
recommended flat plate solar collector type539 as it is
the most robust collector as you mentioned. I have tried
it, it worked pretty good. However, I would think
evacuated tube solar collector type538 is also very robust
and accurate, however the result I am getting is
significantly larger than expected. Then I tried the
simple version Type71 evacuated tube collector, it does
give me decent result. The results difference between
Type538 and Type71 is about 33% which I think it is huge.
Would you recommend Type538 for general use even though I
do think this type is quite sophisticated from what I have
seen in Mathematic description in Tess model? </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">I have one
final question, where could I get information for the
capacitance of collector? I have tried varies manufacture
website, none of them has given this value. If I leave
the default value, is this going to affect my result by
much?</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Thank you
very much for your help.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Zhe Li </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"
lang="EN-US">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"
lang="EN-US"> David BRADLEY [<a moz-do-not-send="true"
href="mailto:d.bradley@tess-inc.com">mailto:d.bradley@tess-inc.com</a>]
<br>
<b>Sent:</b> 16 October 2012 17:04<br>
<b>To:</b> Zhe Li<br>
<b>Cc:</b> <a moz-do-not-send="true"
href="mailto:trnsys-users@cae.wisc.edu">trnsys-users@cae.wisc.edu</a><br>
<b>Subject:</b> Re: [TRNSYS-users] Air source heat
pump system validation</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">Zhe Li,<br>
I look at similar energy balances quite often so I suspect
there is not a systematic problem but something wrong in the
simulation. There are a few things to look at.<br>
<br>
First, make sure that you have some thermal capacitance in
the liquid loop. This will usually take the form of a buffer
tank. The tank should have enough volume to store at least
one timestep of liquid at whatever flow rate your pump is
running. <br>
<br>
Second, look at the controls on your flow loop. Type941 is
basically an ON/OFF device; it does not meet a set point
temperature but simply puts its entire current capacity into
cooling down (or heating up) the liquid loop. Under low load
situations, this can dramatically overheat or overcool the
liquid loop; the tank above should help this a lot.<br>
<br>
Third, make sure that you are using a reasonably short
timestep (1 or 5 minutes). this will allow your system to be
controller appropriately.<br>
<br>
When you look at the energy balance, you have to also look
at the beginning and ending temperature of the liquid loop.
If it is significantly different than it was at the
simulation start, you have to account for stored energy in
your balance.<br>
Kind regards,<br>
David<br>
<br>
<br>
<br>
<o:p></o:p></p>
<div>
<p class="MsoNormal">On 10/16/2012 08:42, Zhe Li wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal">Dear TRNSYS users,<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Thanks for your time. <o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I am currently performing a simple
validation of an air source heat pump system. The
air-source heat pump is Type941, and I am using a defined
thermal load (Type682) with an input file (Type9).
However, the results I am getting for the Total Heat
Transfer to Liquid from output option in air source heat
pump component is between 2 and 3 times higher than the
Heating Load Met from output option in thermal load. I
cannot think of any reason why the generated energy is
significantly higher than the load met. I would
understand if the generated energy is a bit higher than
the load met as there might be heat losses from connected
pipes. <o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Could anyone give me some advices? This
is very important for me to continue my research project.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Thanks very much in advance.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Zhe Li<o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman , serif","serif""><br clear="all">
Tá an teachtaireacht seo scanta ó thaobh ábhar agus
víreas ag Seirbhís Scanta Ríomhphost de chuid Seirbhísí
Faisnéise, ITBÁC agus meastar í a bheith slán. <a
moz-do-not-send="true" href="http://www.dit.ie">http://www.dit.ie</a><br>
This message has been scanned for content and viruses by
the DIT Information Services E-Mail Scanning Service,
and is believed to be clean. <a moz-do-not-send="true"
href="http://www.dit.ie">http://www.dit.ie</a> <br>
<br>
<br>
<br>
</span><o:p></o:p></p>
<pre>_______________________________________________<o:p></o:p></pre>
<pre>TRNSYS-users mailing list<o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="mailto:TRNSYS-users@cae.wisc.edu">TRNSYS-users@cae.wisc.edu</a><o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="https://mailman.cae.wisc.edu/listinfo/trnsys-users">https://mailman.cae.wisc.edu/listinfo/trnsys-users</a><o:p></o:p></pre>
</blockquote>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New Roman
, serif","serif""><br>
<br>
<br>
</span><o:p></o:p></p>
<pre>-- <o:p></o:p></pre>
<pre>***************************<o:p></o:p></pre>
<pre>David BRADLEY<o:p></o:p></pre>
<pre>Principal<o:p></o:p></pre>
<pre>Thermal Energy Systems Specialists, LLC<o:p></o:p></pre>
<pre>22 North Carroll Street - suite 370<o:p></o:p></pre>
<pre>Madison, WI 53703 USA<o:p></o:p></pre>
<pre> <o:p></o:p></pre>
<pre>P:+1.608.274.2577<o:p></o:p></pre>
<pre>F:+1.608.278.1475<o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="mailto:d.bradley@tess-inc.com">d.bradley@tess-inc.com</a><o:p></o:p></pre>
<pre> <o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="http://www.tess-inc.com">http://www.tess-inc.com</a><o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="http://www.trnsys.com">http://www.trnsys.com</a><o:p></o:p></pre>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif""><br clear="all">
Tá an teachtaireacht seo scanta ó thaobh ábhar agus víreas
ag Seirbhís Scanta Ríomhphost de chuid Seirbhísí
Faisnéise, ITBÁC agus meastar í a bheith slán. <a
moz-do-not-send="true" href="http://www.dit.ie">http://www.dit.ie</a><br>
This message has been scanned for content and viruses by
the DIT Information Services E-Mail Scanning Service, and
is believed to be clean. <a moz-do-not-send="true"
href="http://www.dit.ie">http://www.dit.ie</a> <o:p></o:p></span></p>
</blockquote>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
Roman","serif""><br>
<br>
<o:p></o:p></span></p>
<pre>-- <o:p></o:p></pre>
<pre>***************************<o:p></o:p></pre>
<pre>David BRADLEY<o:p></o:p></pre>
<pre>Principal<o:p></o:p></pre>
<pre>Thermal Energy Systems Specialists, LLC<o:p></o:p></pre>
<pre>22 North Carroll Street - suite 370<o:p></o:p></pre>
<pre>Madison, WI 53703 USA<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>P:+1.608.274.2577<o:p></o:p></pre>
<pre>F:+1.608.278.1475<o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="mailto:d.bradley@tess-inc.com">d.bradley@tess-inc.com</a><o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre><a moz-do-not-send="true" href="http://www.tess-inc.com">http://www.tess-inc.com</a><o:p></o:p></pre>
<pre><a moz-do-not-send="true" href="http://www.trnsys.com">http://www.trnsys.com</a><o:p></o:p></pre>
</div>
<br clear="all">
Tá an teachtaireacht seo scanta ó thaobh ábhar agus víreas ag
Seirbhís Scanta Ríomhphost de chuid Seirbhísí Faisnéise, ITBÁC
agus meastar í a bheith slán. <a moz-do-not-send="true"
href="http://www.dit.ie">http://www.dit.ie</a><br>
This message has been scanned for content and viruses by the DIT
Information Services E-Mail Scanning Service, and is believed to
be clean. <a moz-do-not-send="true" href="http://www.dit.ie">http://www.dit.ie</a>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI 53703 USA
P:+1.608.274.2577
F:+1.608.278.1475
<a class="moz-txt-link-abbreviated" href="mailto:d.bradley@tess-inc.com">d.bradley@tess-inc.com</a>
<a class="moz-txt-link-freetext" href="http://www.tess-inc.com">http://www.tess-inc.com</a>
<a class="moz-txt-link-freetext" href="http://www.trnsys.com">http://www.trnsys.com</a></pre>
</body>
</html>