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Jace,<br>
Make sure that wherever possible, you are passing around the
atmospheric pressure to the components. Often times the air is not
saturated if you know the pressure but is saturated if you assume that
pressure is 1atm. The rest of the answer depends a bit on what kind of
weather data you are using. If you are using a "standard format"
weather file such as TMY2, meteonorm, etc. then the values should be
corrected for pressure. The other piece of advice that I would give is
that wherever possible, try to pass relative humidity around instead of
humidity ratio. The humidity ratio values are so small that when you
apply the convergence tolerance of 0.001 or better 0.0001, even a tiny
tiny change in humidity ratio can begin to cause some convergence
issues. If you use RH, the values are less sensitive.<br>
Best,<br>
David<br>
<br>
<br>
On 6/16/2010 01:15, LE GALL, Jace wrote:
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<p class="MsoNormal">Dear All,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am currently using TRNSys to model an HVAC
installation
but when using the weather data from humid regions such as Singapore or
Hong Kong,
I have a recurrent message on different units such as Type52b cooling
coil,
Type667c heat recovery wheel and Type88 single zone model.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Message : The referenced UNIT as called the
PSYCHROMETRICS
routine one or more times during the simulation withan enthalpy greater
than
that for saturated air and the given dry bulb temperature. The air was
assumed
saturated and the enthalpy set for this condition.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I assume that this error leads to more errors in
the final energy
given as a result and eventually, even manage to crash my simulation
when I
lower the time step too much, as the number of messages is limited to
500. I
based my calculations on the hypothesis that the humidity ratio asked
in the different
units is the absolute humidity ratio with is kg of water / kg of dry
air. I
have isolated Type52b cooling coil to search more deeply my possible
mistakes
(constant humidity ratio of 0.02kgw/kga and wet bulb temperature
varying from 27
to 33). According to my psychometric chart (at sea level), the air
shouldn’t
reach saturation but TRNSys tells me the opposite.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Has anyone encountered a similar problem in a
simulation and
was able to solve it?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Best Regards,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Jace LE GALL<o:p></o:p></p>
</div>
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***************************
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
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