I couldn't have said it better. FWIW Garnier Fructise makes some pretty good hair color.<br><br>What I was trying to do is what Nick suggested you do, conceptualize what your system(s) are really doing, i.e heating air, exhausting air, returning air, etc., all at or to specific temperatures. So w/2 DOAS systems I would operate them this way: DOAS1 will have exhaust air entering and passing through one side of the enthalpy ERV in the DOAS at a temperature of about 75 F or so. The OA will be entering at whatever temperature it is at and it will pick up the heat/cool from the exhaust at the rate of cfm x the effectiveness of the ERV. If you specify this ERV as and enthalpy wheel/Hx not only will your air be heated/cooled, it will also be dehumidified somewhat. In DOAS2 this air then mixes with the return air and gets heated to 95 F or so and delivered to the space. <br>
<br><font size="2"><span style="font-size: 10pt; font-family: Arial;"> A comment about the way you are proposing to do this: DOAS that has an ERV device located downstream
after a heating and a cooling coil. I think this system would be an energy hog because you would be heating your air prior to recovering heat from the exhaust air. If a DOAS system can help w/dehumidification enough, I'd try it first.</span></font> Take a good look at your reports to see if it's working okay.<br>
<br>Regards,<br><br>Carol<br><br>PS Are you sure the dehumidification algorithms in eQUEST are still not working? I'd check to see if the problems have been fixed.<br><br><div class="gmail_quote">On Tue, Oct 19, 2010 at 9:49 AM, Nick Caton <span dir="ltr"><<a href="mailto:ncaton@smithboucher.com">ncaton@smithboucher.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div link="blue" vlink="purple" lang="EN-US">
<div>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Kathryn,</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">I may be mistaken, but I think you’re causing yourself to
run in circles by trying to think of DOAS systems as they exist in the real
world instead of how we can account for in eQuest. I did this for a long time
before “getting it…”</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">To answer one of your first questions, take another look at the
second screen where you define ERU components under “cond/frost control.”
You can explicitly model pre-heating the OA before the ERU wheel/HX with either
electricity or HW to either a floating or fixed setpoint.</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Carol is cautioning you to avoid specifying too many systems –
and you may have inadvertently hit the nail on the head with your last words “...come
up with an equivalent.” </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">While your real world system looks something like:</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">DOAS preconditioning box </span><span style="font-size: 11pt; font-family: Wingdings; color: rgb(31, 73, 125);">à</span><span style="font-size: 11pt; color: rgb(31, 73, 125);"> ERU box with a wheel </span><span style="font-size: 11pt; font-family: Wingdings; color: rgb(31, 73, 125);">à</span><span style="font-size: 11pt; color: rgb(31, 73, 125);"> big AHU
box </span><span style="font-size: 11pt; font-family: Wingdings; color: rgb(31, 73, 125);">à</span><span style="font-size: 11pt; font-family: Wingdings; color: rgb(31, 73, 125);">àà</span><span style="font-size: 11pt; color: rgb(31, 73, 125);"> multiple
Fancoil boxes</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Your eQuest equivalent to the above is ideally:</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">One system, with most components/airflows defined at the system
level and a some at the zonal level.</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Trying to make the “real world” distinction between
the various parts of your system will require you to jump through hoops to
ensure the correct quantities of OA and EA are going through the various
components. It’s conceptually possible with a dummy
zone/loads/scheduling and a lot of coffee, but if you really try to model that
may distinct systems and make them all dance in a line for a single group of
zones, you’re bound to lose sleep and grow some gray hairs in the process.
This has been my experience.</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">I think you’ll also find eQuest can indeed model desiccant
energy recovery very well, with a lot of flexibility, so take heart!</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">~Nick</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<div>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"><img src="cid:image001.jpg@01CB6F80.CBC407B0" alt="cid:489575314@22072009-0ABB" height="37" width="119"></span><b><span style="font-size: 11pt; color: rgb(45, 77, 94);"></span></b></p>
<p class="MsoNormal"><b><span style="font-size: 11pt; color: rgb(45, 77, 94);"> </span></b></p>
<p class="MsoNormal"><b><span style="font-size: 11pt; color: rgb(45, 77, 94);">NICK CATON, E.I.T.</span></b><b><span style="color: rgb(45, 77, 94);"></span></b></p>
<p class="MsoNormal"><span style="font-size: 7.5pt; color: rgb(204, 153, 0);">PROJECT ENGINEER</span><span style="font-size: 7.5pt; color: rgb(204, 153, 0);"></span></p>
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</div>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);"> </span></p>
<div>
<div style="border-width: 1pt medium medium; border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; padding: 3pt 0in 0in;">
<p class="MsoNormal"><b><span style="font-size: 10pt;">From:</span></b><span style="font-size: 10pt;">
<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a>
[mailto:<a href="mailto:equest-users-bounces@lists.onebuilding.org" target="_blank">equest-users-bounces@lists.onebuilding.org</a>] <b>On Behalf Of </b>Kathryn
Kerns<br>
<b>Sent:</b> Tuesday, October 19, 2010 11:08 AM<br>
<b>To:</b> Carol Gardner<div><div></div><div class="h5"><br>
<b>Cc:</b> <a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> Re: [Equest-users] Multiple DOAS in Series</div></div></span></p>
</div>
</div><div><div></div><div class="h5">
<p class="MsoNormal"> </p>
<div>
<div>
<p class="MsoNormal"><span style="font-size: 10pt; color: black;">Carol, I am not sure I understand what you mean. Can you draw a
picture or explain further? If I have one DOAS, how do I go about specifying
entering conditions for its ERV other than outside air and exhaust?</span></p>
</div>
<div>
<p class="MsoNormal"> </p>
</div>
<div>
<p class="MsoNormal"><span style="font-size: 10pt;">I
am also wondering just exactly what happens to DOAS supply air. According to
the literature it appears that the outside air is fed through the DOAS, which
then heats it and cools it via the DOAS entered heating and cooling supply
temperatures, and then the supply air is passed
to the associated space air (which I assume has the normal space
temperature range of 70 to 78) which it then transmitted to the downstream
terminal units as their primary air. At least I think this is what I think I
read.</span></p>
</div>
</div>
<div>
<p class="MsoNormal"> </p>
</div>
<div>
<p class="MsoNormal">Does anyone else have a different interpretation? Maybe we
are passing the DOAS supply air to the terminal units at the supply
heating and cooling temperatures the same way the DOAS supply
air gets passed to its associated space?</p>
</div>
<div>
<p class="MsoNormal"> </p>
</div>
<div>
<p class="MsoNormal">If I figure this out, I will share the results. Desiccant
systems like the one I am modeling are being used more and more often as energy
savers in humid climates. Somehow we need to figure this out or come up
with an equivalent.</p>
</div>
<div>
<p class="MsoNormal"> </p>
</div>
<div>
<div class="MsoNormal" style="text-align: center;" align="center">
<hr align="center" width="100%" size="2">
</div>
</div>
<div>
<p class="MsoNormal" style="margin-bottom: 12pt;"><b><span style="font-size: 10pt;">From:</span></b><span style="font-size: 10pt;"> Carol Gardner [mailto:<a href="mailto:cmg750@gmail.com" target="_blank">cmg750@gmail.com</a>]<br>
<b>Sent:</b> Mon 10/18/2010 7:45 PM<br>
<b>To:</b> Kathryn Kerns<br>
<b>Cc:</b> <a href="mailto:equest-users@lists.onebuilding.org" target="_blank">equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> Re: [Equest-users] Multiple DOAS in Series</span></p>
</div>
<div>
<p class="MsoNormal" style="margin-bottom: 12pt;">Hi Kathryn,<br>
<br>
Just a couple of quick thoughts. Do you need to physically specify 2 DOAS
units? Could you just specify one with an ERV and with the entering conditions
of the first unit and the leaving conditions of the second unit? I'm not
thinking of any downside to doing it that way but I'm not deep in it like you
are. Let me know what you think.<br>
<br>
Cheers,<br>
<br>
Carol</p>
<div>
<p class="MsoNormal">On Mon, Oct 18, 2010 at 2:06 PM, Kathryn Kerns <<a href="mailto:kathryn.kerns@bceengineers.com" target="_blank">kathryn.kerns@bceengineers.com</a>>
wrote:</p>
<div>
<div>
<p class="MsoNormal"><span style="font-size: 10pt;">Has anyone ever tried
to model 2 DOAS units in series? I have successfully modeled a single
DOAS/multiple fan coil system, but I have never tried to string two DOAS units
together by feeding the supply air output of the first DOAS into the outside
air input of the second DOAS. The reason I ask is that I am looking for a way
to model a DOAS that has an ERV device located downstream after a heating and a
cooling coil. Does anyone know whether DOE-2 would treat the system
exhaust air coming back through the second DOAS ERV any differently than the
exhaust air going back through a single DOAS with an ERV unit? </span></p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="font-size: 10pt;">Assuming that this
works, does anybody know how to add heat to, or manually raise the temperature
of, the ERV exhaust air? </span></p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="font-size: 10pt;">I am thinking if I
can model a multiple DOAS with an elevated exhaust temperature, I might be able
to mimic a desiccant system. According to James Hirsch in California, the
energy balance used in the desiccant tabs is not correct and should not be
used, so I am out of luck there.</span></p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"><span style="font-size: 10pt;">If anyone has another
method for modeling a desiccant system, I would love to hear from you.</span></p>
<p class="MsoNormal"> </p>
<p style="margin: 0in 0in 0.0001pt;"><b><span style="color: black;">Kathryn Kerns</span></b></p>
<p style="margin: 0in 0in 0.0001pt;"><b><span style="font-size: 11pt;">Systems Specialist</span></b></p>
<p style="margin: 0in 0in 0.0001pt;"><b><span style="font-variant: small-caps; color: teal;">BCE</span></b><b><span style="font-size: 10pt; font-variant: small-caps; color: teal;"> </span><span style="font-variant: small-caps; color: teal;">Engineers,
Inc.</span></b></p>
<p style="margin: 0in 0in 0.0001pt;"><b><span style="font-size: 9pt; color: black;">| Ph: 253.922.0446 | Fx: 253.922.0896 |</span></b><span style="font-size: 7pt; color: black;"> </span></p>
<p class="MsoNormal"> </p>
<p class="MsoNormal"> </p>
</div>
</div>
<p class="MsoNormal" style="margin-bottom: 12pt;"><br>
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<p class="MsoNormal"><br>
<br clear="all">
<br>
-- <br>
Carol Gardner PE</p>
</div>
</div></div></div>
</div>
</blockquote></div><br><br clear="all"><br>-- <br>Carol Gardner PE<br>
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