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Yujun,<br>
I am not sure that there is anything wrong with the simulation; you
have 18 airchanges per hour of ambient air that is somewhere between 16
and 21C going into the space and that is keeping the zone temperature
below 26C when the cooling would turn on. If you switch off your
natural ventilation by multiplying the equation by zero, you'll see
that the space gets up to the cooling temperature every day. <br>
<br>
You should probably multiply the zone capacitance by 5 or 10. The
value that you have for the zone accounts only for the thermal
capacitance of the zone air (it ignores the capacitance of all the
other things in the zone like shelving, products, furniture, etc.). You
should also set the humidity capacitance multiplier to a value of about
5 to account for the furniture's capacity to absorb moisture. Lastly, I
think that a 1 hour timestep might be too long. Bear in mind that the
decision to activate or deactivate the natural ventilation system can
only be made once per timestep. The fact that the natural ventilation
is on for one time step, then off for one time step, then back on for a
time step suggests to me that the system isn't very stable.<br>
<br>
Best, <br>
David<br>
<br>
<br>
Yujun TAO wrote:
<blockquote cite="mid:214494.30580.qm@web28603.mail.ukl.yahoo.com"
type="cite">
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<div>Hello,<br>
I simulated a cooling commercial with a natural ventilation, the
natural ventilation is modeled in a equation.<br>
I don't understand why there is abnormal fluctuation of Qcool curve and
the temperature doesn't reach 26 degrees.<br>
I feel it maybe concern the equation.<br>
Could someone help me? <br>
</div>
</div>
<br>
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