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Ryan,<br>
There are (at least) two ways that you can approach this. One way
is to write some equations using Boolean functions that enable and
disable the economizer and chiller based on ambient temperature.
Please see my response earlier today to a post called "Control
signal for GSHP" to some tips on setting these equations. <br>
<br>
It is slightly different from the control logic you describe but
you could also make use of the multi stage cooling ability in the
Type108 thermostat model. You could use this model to enable the
economizer if the zone temperature gets to a certain temperature but
then turn off the economizer and turn on the chiller if the room
temperature continues to rise to a second setpoint temperature.<br>
Kind regards,<br>
David<br>
<br>
<br>
<div class="moz-cite-prefix">On 2/7/2014 04:06, Jian Yan wrote:<br>
</div>
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<div>Hello dears,</div>
<div><br>
</div>
<div>I'm recently building a thermal model of a server room
in TRNSYS 17, where two types of cooling systems are
applied, chiller and economizer. My goal is to cool the
server room by the chiller when the ambient temperature is
above 18 centigrade, while using free cooling (economizer)
when the temperature is below 18 centigrade. </div>
<div><br>
</div>
<div>The chiller system is already built and functional,
however, I have no clue how to enable the model switch
between the two cooling systems automatically according to
the outdoor temperature, like how to set the temperature
sensor, valve or other staffs.</div>
<div><br>
</div>
<div>Thank you very much in advance.</div>
<div><br>
</div>
<div>Best regards,</div>
<div>Ryan</div>
<div><br>
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<pre class="moz-signature" cols="72">--
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI 53703 USA
P:+1.608.274.2577
F:+1.608.278.1475
<a class="moz-txt-link-abbreviated" href="mailto:d.bradley@tess-inc.com">d.bradley@tess-inc.com</a>
<a class="moz-txt-link-freetext" href="http://www.tess-inc.com">http://www.tess-inc.com</a>
<a class="moz-txt-link-freetext" href="http://www.trnsys.com">http://www.trnsys.com</a></pre>
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