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Dear Jim,<br>
<br>
I like the idea of a single external Chiller. This should be fine
for most of our tools. However a few equipments are more sensitive
demanding higher flow and or pressure...<br>
<br>
The combination an external chiller and a few smaller ones line
could be the best solution for us, having a small backup chiller in
case of urgent need...<br>
<br>
I am curious to know the number of technicians you have in a
facility with 40-50 tools... <br>
Here, ww can afford only one ;-/<br>
<br>
<br>
best,<br>
Loïk.<br>
<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">Le 16/03/2015 17:25, Beall, James A. a
écrit :<br>
</div>
<blockquote cite="mid:614FCF45-FCFE-4B0B-B085-F2FCA4619E2E@nist.gov"
type="cite">
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Loïk,
<div><br>
</div>
<div>I agree with the caution about accounting for the heat from
the FFU; it is significant.</div>
<div><br>
</div>
<div>In our fabs we use a large external Process Chilled Water
unit which provides cooling for 40-50 tools. Some of the
equipment (like cryopump compressors and larger pumps which
typically have larger => 3/8” diameter), cooling lines can be
directly cooled by the PCW loop. Many other tools like electron
gun evaporators and sputter guns have smaller cooling lines and
you may have trouble directly connecting them to the PCW loop
and achieving the required flows and pressures. </div>
<div><br>
</div>
<div>We end up with many small heat exchangers each set up for the
particular needs of our tools. Some run distilled water, some DI
water, some glycol and some high temperature thermal fluids. The
pumps are the weak point in these units.</div>
<div><br>
</div>
<div>When connecting tools across your PCW loop be careful to
include balancing or flow setting valves as you will have many
connections in parallel. </div>
<div><br>
</div>
<div>Also I prefer to use a non-closed system, i.e., one with an
atmospheric pressure return tank. This can be automatically
refilled with treated water as needed to account for leaks and
losses. Having your return water dump into a non-pressurized
tank creates much less back pressure than the closed loop
pressurized systems. The back pressure can be a killer with many
parallel connected tools with different impedances.</div>
<div><br>
</div>
<div><br>
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- Jim</div>
<br class="Apple-interchange-newline">
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<br>
<div>
<div>On Mar 16, 2015, at 11:41 AM, Iulian Codreanu <<a
moz-do-not-send="true" href="mailto:codreanu@udel.edu">codreanu@udel.edu</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<blockquote type="cite">
<div bgcolor="#FFFFFF" text="#000000">Loik,<br>
<br>
Another thing to keep in mind is the heat that is "taken
away from the equipment" via exhaust.<br>
<br>
The heat generated by a piece of equipment can:<br>
-Be dissipated into the room<br>
-Be "taken away" by the cooling water.<br>
-Be "taken way" by exhaust.<br>
<br>
If a piece of equipment is not cooled and does not have
exhaust then all the heat gets dissipated into the room.<br>
<br>
If the piece of equipment is cooled and exhausted only
part of the heat generated will end up in the room.<br>
<br>
If you know how much heat is taken away by the cooling
water and/or exhaust that is great. If you do not, I saw
engineers using factor such as (PCW stands for process
cooling water):<br>
100% of the power into the room if no PCW and no exhaust<br>
50% of the power into the room is no PCW but exhaust<br>
40% of the power into the room if PCW but no exhaust<br>
20% of the power into the room if both PCW and exhaust<br>
<br>
I prefer the "unique chiller (placed outside of the
building)" approach for cooling the equipment. If you can
run the water from the unique chiller directly through the
equipment, you do not have to deal with the heat generated
by the "small chillers".<br>
<br>
Iulian<br>
<br>
<br>
<br>
<pre class="moz-signature" cols="72">iulian Codreanu, Ph.D.
Director of Operations, UD NanoFab
163 ISE Lab
221 Academy Street
Newark, DE 19716
302-831-2784
<a moz-do-not-send="true" class="moz-txt-link-freetext" href="http://udnf.udel.edu/">http://udnf.udel.edu</a></pre>
<div class="moz-cite-prefix">On 3/16/2015 10:36 AM, Loïk
GENCE wrote:<br>
</div>
<blockquote cite="mid:5506EA62.9000008@cetuc.puc-rio.br"
type="cite">Hi Everyone,<br>
<br>
I am working on the design of a small cleanroom facility
(70m2) ISO 5/6. Right now, I am dealing with the problem
of thermal load,<br>
Which is crucial here in Rio, where the average outside
temperature is of 30 deg C with a relative humidity of
75-80 %.<br>
<br>
I would like to have your help and/or comments on
several points:<br>
<br>
Most of the manufacturers do not provide a value for the
thermal load (why?). Assuming 2 or max 3 people working
simultaneously in the cleanrooms, and usual cleanroom
value: 22 deg C - 55% humidity. The main issue is: how
can I estimate the cooling power required for the Air
Conditioning System (ACS)?<br>
<br>
I have the list of equipments we'll have and the
corresponding electrical power. I assumed the heat
generated by 2 users and added the total electrical
power dissipated as heat inside of the cleanroom, using
a simultaneity factor of 0.75 (all equipments won't be
turned on at the same time) and neglected the heat
produced by the filter fan and lightning.
<br>
<b> </b><b><br>
</b><b> - Is it reasonable for dimensioning the
ACS cooling power ? </b><br>
<br>
Also most of the equipments have a cooling water
circuit. But the cooling power needed is well described
in the installation manual provided with the equipments.
<br>
<br>
<b> - Should I subtract from the </b><b>ACS
cooling power</b><b> value, </b><b> the cooling po</b><b>wer
</b><b>from the chillers?</b><br>
<br>
- <b>Do you think a central and unique chiller
(placed outside of the building) is preferred to
several smaller chillers placed closer to the
equipment?</b><br>
<br>
<br>
I thank you very much for your kind help or comments.<br>
<br>
<br>
regards,<br>
<br>
Loïk.<br>
<br>
<pre class="moz-signature" cols="72">--
__________________________________________
Dr. Loïk Gence
PUC-RIO/CETUC-LABSEM
End Rua Marques de São Vicente, 225-Gavea
CEP:22451-900 Rio de Janeiro, RJ-Brasil
(Telefone) +55 (021) 3527-2193
(Mobile) +55 (021) 99156-5558
<a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:loik.gence@cetuc.puc-rio.br">loik.gence@cetuc.puc-rio.br</a>
__________________________________________</pre>
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<pre class="moz-signature" cols="72">--
__________________________________________
Dr. Loïk Gence
PUC-RIO/CETUC-LABSEM
End Rua Marques de São Vicente, 225-Gavea
CEP:22451-900 Rio de Janeiro, RJ-Brasil
(Telefone) +55 (021) 3527-2193
(Mobile) +55 (021) 99156-5558
<a class="moz-txt-link-abbreviated" href="mailto:loik.gence@cetuc.puc-rio.br">loik.gence@cetuc.puc-rio.br</a>
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