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<p class=MsoNormal>Hello,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I was almost sure that eQUEST/DOE-2.2 had a built-in control
mode to reset the tower-leaving condenser-water setpoint relative to outdoor
wet-bulb temperature. After puzzling over why I couldn’t find it in
the GUI, I eventually realized that I was thinking of EnergyPro/DOE-2.1e.
This is a fairly common control strategy for open towers, so I was wondering
why this feature disappeared between DOE-2 releases and what others are doing
to simulate this control mode using eQUEST.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Of course, COOL-SETPT-CTRL = OA-RESET is based on
dry-bulb. So you could assume a constant wet-bulb depression and use a
SUPPLY-LO greater than SUPPLY-HI (this is allowed, right?), but this is very
crude.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I guess you could use COOL-SETPT-CTRL = SCHEDULED, parse the
hourly wet-bulb temps out of the weather file, add the tower design approach to
everything, and dump those values into a COOL-SETPT-SCH (hopefully using a perl
script or something). However, SCHEDULEs are limited to 12
WEEK-SCHEDULEs, so it’s not really possible to define a schedule of 8760
arbitrary values. But even if you could, it seems to me that
there’s a reason the weather file has hourly wet-bulb data in it, and one
of them is to avoid having to do stuff like this… <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I had thought of using user expressions, but I think eQUEST
evaluates these when it generates the BDL, so they wouldn’t be evaluated
during the simulation for each hour. I’m pretty sure there’s
no user variable for current outdoor wet-bulb temp anyway, because this
isn’t something that can be evaluated ahead of time. Is this
something that can be done with DOE-2 subroutines/functions (I haven’t
played with those yet)? Something like:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>MAGIC-EXPRESSION = OA-WB-T + DESIGN-APPROACH ..<o:p></o:p></p>
<p class=MsoNormal>TWR-SETPT-SCH = SCHEDULE THRU DEC 31 (ALL) (1,24)
(MAGIC-EXPRESSION) ..<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The idea is that MAGIC-EXPRESSION would be evaluated every
time DOE-2 references the value of TWR-SETPT-SCH for the current hour.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Should I put this on the list of ECMs where I have to tell
people that I can’t really model that, or is there hope after all?<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Thanks,<o:p></o:p></p>
<p class=MsoNormal>Jeff<b><span style='font-size:8.0pt;font-family:"Verdana","sans-serif";
color:#135351'> </span></b><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span
style='font-size:8.0pt;font-family:"Verdana","sans-serif";color:#135351'>Jeff
Saretsky</span></b><b><span style='font-size:9.0pt;font-family:"Verdana","sans-serif";
color:#135351'><br>
</span></b><span style='font-size:7.0pt;font-family:"Verdana","sans-serif";
color:#B2550C'>Energy Modeler<br>
</span><span style='font-size:7.5pt;font-family:"Verdana","sans-serif";
color:#B2550C'>___________________________<br>
</span><span style='font-size:10.5pt;font-family:"Arial Black","sans-serif";
color:#135351'>RUMSEY</span><span style='font-size:13.5pt;font-family:"Arial Black","sans-serif";
color:#135351'><br>
</span><span style='font-size:6.0pt;font-family:"Tahoma","sans-serif";
color:#B2550C'>E N G I N E E R S<br>
</span><span style='font-size:7.0pt;font-family:"Verdana","sans-serif";
color:#B2550C'>Energy Efficient Design <br>
99 Linden Street<br>
Oakland CA 94607<br>
510 663 2070 x238<br>
fax 510 663 2080<br>
<a href="mailto:jsaretsky@rumseyengineers.com">jsaretsky@rumseyengineers.com</a><br>
</span><u><span style='font-size:9.0pt;font-family:"Verdana","sans-serif";
color:#B2550C'><a href="http://www.rumseyengineers.com/"><span
style='font-size:7.0pt;color:#B2550C'>www.rumseyengineers.com</span></a></span></u><span
style='font-size:7.5pt;font-family:"Verdana","sans-serif";color:#B2550C'><br>
___________________________</span><b><span style='font-size:7.0pt;font-family:
"Verdana","sans-serif";color:#135351'><o:p></o:p></span></b></p>
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