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Art,<br>
<br>
<div class="moz-cite-prefix">On 10/8/2013 12:27 PM, Art Krenzel
wrote:<br>
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<blockquote cite="mid:BAY169-W10776441BEF82C45101737B9B1C0@phx.gbl"
type="cite">
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<div dir="ltr">Stephen:<br>
<br>
Take a look at this company who produces a modern commercial
sized thermal refrigerator system. This unit may be too large
for your application but it is easier to downsize a design than
upsize.<br>
<br>
<a moz-do-not-send="true"
href="https://bay169.mail.live.com/default.aspx?n=77550718&fid=1&mid=069dc4c6-3049-11e3-a4d7-00237de46188&fv=1#n=14993950&fid=2&mid=dec4048c-3030-11e3-b579-00237de3f534&fv=1">https://bay169.mail.live.com/default.aspx?n=77550718&fid=1&mid=069dc4c6-3049-11e3-a4d7-00237de46188&fv=1#n=14993950&fid=2&mid=dec4048c-3030-11e3-b579-00237de3f534&fv=1</a>
<br>
<br>
The Sevel sized refrigerators are quite small for most
commercial milk applications.<br>
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</blockquote>
<br>
The link is specific to you, given that it requires a log-in...<br>
<br>
<br>
More to the main point, we would have to ask Stephen Etheridge for
his thought, but I took it that when he asked Samantha Carter "<span
style="color: rgb(31, 73, 125); font-family:
"Calibri","sans-serif"; font-size: 11pt;">Why
not use a gas fridge?"</span>, he was referring to absorption
cycle refrigeration, the technology used in the Servel or Dometic
refrigerators, of whatever size. As you may recall, strict or "pure"
ACR uses only heat for power, whereas most modern chillers, AC
systems and refrigerators use an additional or a different power
source to provide for mechanical compression, which greatly
increases what stands in the stead of ordinary efficiency for most
such applications, which is the coefficient of performance. <br>
<br>
As you no doubt realize, COP is used rather than ordinary
efficiency, where COP is <span class="st"> the ratio of the heating
or cooling which results when divided by the amount of supplied
energy consumed. In the case of heat pumps the ratio can be
greater than one.</span> (Indeed, a COP of 4 or 5 is not
uncommon.) In other words, the energy provided by the ground or air
to the heat pump system is not counted, such that one ends up with a
system which can appear to be or be calculated as well better than
100% efficient, an outcome disallowed by thermodynamics. <br>
<br>
By contrast, the COP of a pure ACR system might be 0.15-0.25, or,
where there is electricity available to pump the working fluid
around (without compression), and blow air or pump water over its
cooling coils, that COP might be increased. (Thus as compared with a
system that uses a heat pump and has a COP of, say, 3, an ACR system
with a COP of 0.25 is rather less than 10% as efficient.)<br>
<br>
Of course, to start back at the beginning, where one has only
biogas, and refrigeration is wanted, then pure ACR is the AD-powered
option, even if it is inefficient. And where electricity <i>is</i>
available, then ACR makes limited sense from a COP standpoint,
whatever the scale of the operation.<br>
<br>
<br>
Samantha said, of course, that the present thought is to use what is
already installed-- a unit, as I understand it, that requires
electricity-- so in the specific case, the point is moot, but again,
in the general case, where there is enough biogas to produce
electricity, it is generally better to do so and use that energy to
provide cooling.<br>
<br>
<br>
<br>
<br>
d.<br>
<div class="moz-signature">-- <br>
<div style="font:Georgia" ;=""><span style="font-size:110%;">David
William House<br>
</span>
<div style="padding-left:3em;font-size:80%;">"The Complete
Biogas Handbook" <code><a href="www.completebiogas.com">www.completebiogas.com</a></code><br>
<em>Vahid Biogas</em>, an alternative energy consultancy <code><a
href="www.vahidbiogas.com">www.vahidbiogas.com</a><br>
<br>
</code></div>
<code>
<div style="padding-left:2em;">"Make no search for water.
But find thirst,<br>
And water from the very ground will burst."
<div style="padding-left:2em;font-size:80%;">(Rumi, a
Persian mystic poet, quoted in <em>Delight of Hearts</em>,
p. 77) <br>
<br>
<a class="moz-txt-link-freetext" href="http://bahai.us/">http://bahai.us/</a></div>
</div>
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