<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">The expected efficiency would be from (a) having all of the target surface in contact with the fluid, and, <div>(b) eliminating the need to conduct heat through the absorber. <br><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div>Clarke </div><div><br></div></span><br></span></div>
<br><div><div>On Oct 12, 2011, at 1:01 PM, Joe Killian wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">
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<font size="+1">MTD = Modified Trickle Down - After Thomason's
early designs as in the Vermont customs building which were named
Trickle Down.<br>
<br>
Thomason's design trickled water down the troughs in metal
roofing, with a glazing a few inches above. Many thought
condensing on the glazing would render the approach useless, but
it turned out to work quite well, albeit with temperatures lower
than we are accustomed to in flat plate collectors. The lower
temperatures contribute to increasing the collecting efficiency.<br>
<br>
There have been several designs under the MTD label, all of which
capture the water between two sheets, both of which are usually
behind glazing. The object being to eliminate the issue of
condensing water on your glazing surface and the accompanying
losses. I believe all these approaches have used some material
between the two sheets to help distribute the water flow to better
collect the heat - as Gary's piece in Build It Solar amply shows
is needed. <br>
<br>
These sheets are usually (always?) plastic, not much of a heat
conductor. But it's thin, with water immediately on the back
side, so we're conducting heat through a few mils of plastic, not
along several inches of the material as in copper fins in a flat
plat collector.<br>
<br>
Joe<br>
</font><br>
On 10/11/2011 2:57 PM, Clarke Olsen wrote:
<blockquote cite="mid:C1FFAF64-18E7-410B-9119-D3DE9ACCD4D3@fairpoint.net" type="cite">
<pre wrap="">What does MTD stand for? I would think that the absorber plate should not be a conductor, but a material keeping it's heat on the surface.
Clarke Olsen
On Oct 11, 2011, at 4:24 PM, Gary BIs wrote:
</pre>
<blockquote type="cite">
<pre wrap="">The MTD collector uses black polyester felt to spread the water across the full surface of a metal backing plate.
I've wondered about the life of the felt, but some of the MTD collectors are about 5 years old and the owners report they are doing well so far.
Gary
On 12:59 PM, Corwyn wrote:
</pre>
<blockquote type="cite">
<pre wrap="">On 10/11/2011 10:56 AM, Gary BIs wrote:
</pre>
<blockquote type="cite">
<pre wrap="">Hi Joe,
Yes -- I'm eager to see how the traditional flat plate compares to the
MTD -- I think that the the MTD might do fine.
I'm probably a bit prejudiced on this, but I think from a life and long
term maintenance point of view, the traditional flat plate may have some
advantages. I'm just a little concerned about keeping the trickle tube
trickling over 20 years.
</pre>
</blockquote>
<pre wrap="">I suspect that a _mostly_ wet cotton towel would not have a very long lifespan. And when it dies, it could well take the pump with it.
Thank You Kindly,
Corwyn
</pre>
</blockquote>
<pre wrap="">
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