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<DIV>Hi Matt,</DIV>
<DIV> </DIV>
<DIV>Thanks for the detailed explanation. I will try to shorten the timestep.
Actually, I also tried adding a pipe between the cooling coil and chiller to
store adequate flow as mentioned in the documentation which I neglected before.
And it works pretty well and I will look into the other warnings you mentioned.
Thanks for your help again.</DIV>
<DIV> </DIV>
<DIV>Best regards,</DIV>
<DIV>Billy </DIV>
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<DIV style="font-color: black"><B>From:</B> <A title=duffy@tess-inc.com
href="mailto:duffy@tess-inc.com">Matt Duffy</A> </DIV>
<DIV><B>Sent:</B> Monday, February 20, 2012 8:53 AM</DIV>
<DIV><B>To:</B> <A title=coolbilly1999@gmail.com
href="mailto:coolbilly1999@gmail.com">Billy Chen</A> ; <A
title=trnsys-users@cae.wisc.edu
href="mailto:trnsys-users@cae.wisc.edu">trnsys-users@cae.wisc.edu</A> </DIV>
<DIV><B>Subject:</B> Re: [TRNSYS-users] Need helps to solve the absorption
chiller (Type677) issue</DIV></DIV></DIV>
<DIV> </DIV></DIV>
<DIV
style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none">Billy,<BR><BR>I
looked at your listing file, and I noticed other important things about your
simulation. First of all, the timestep you are using is much too large. You will
notice in the TESS HVAC Solar Absorption example, the timestep is 5 minutes
(note the equation in the control cards to implement this) in order to consider
the control decisions and flow rates during that timestep. When using a large
timestep, an extraordinary amount of fluid is being sent through your system,
and if you are not simulating adequate capacitance or storage in that loop, it
will lead to components not converging. Also, please note the other warnings at
the end of your listing file about the independent variables being above or
below the specified range in the performance data files. The TRNSYS data
interpolation routine does not extrapolate, so if you send it an independent
variable that is not within the specified range, it will use the dependent
variable at that end(or beginning) of the range and not extrapolate.<BR><BR>Best
regards,<BR><BR>Matt Duffy<BR><BR><BR><!--replyfwdwrap-->
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Original Message -----</STRONG><BR><STRONG>From:</STRONG> "Billy Chen"
<coolbilly1999@gmail.com> <BR><STRONG>Sent:</STRONG> Fri, February 17,
2012 17:22<BR><STRONG>Subject:</STRONG> [TRNSYS-users] Need helps to solve the
absorption chiller (Type677) issue<BR><BR>
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<DIV>Hi TRNSYS users,</DIV>
<DIV> </DIV>
<DIV>I am building an absorption chiller model for a medium office, and I
used the similar components from the TESS example (Restaurant with
absorption chiller). However, when I ran the simulation, I got tons of
warnings (from SYS Message 441), and the simulation terminated because it
exceeded the limit of warnings. The warning said as below:</DIV>
<DIV> </DIV>
<DIV>*** Warning at time
: 3717.000000<BR>
Generated by Unit : Not applicable or not
available<BR> Generated by Type
: Not applicable or not available<BR> TRNSYS
Message 441 : The inputs to the listed units have not
converged at this timestep. The values at the last iteration will be used
and the simulation will proceed.<BR> Reported
information : UNITS: 12 13 18</DIV>
<DIV> </DIV>
<DIV>UNIT 12 is Type 677 double effect chiller</DIV>
<DIV>UNIT 13 is Type 144 pump</DIV>
<DIV>UNIT 18 is Type 697b cooling coil</DIV>
<DIV> </DIV>
<DIV>I checked the input units and I can't figure out the problem. Could
someone give me some advice?</DIV>
<DIV> </DIV>
<DIV>And I also found out a problem when I ran the TESS Restaurant
example, the chilled water outlet temperature is always going up over 100
degree C. But the temperature from the air temperature from cooling
coil looks reasonable. It confuses me a lot. Does anyone find this problem
before and have any suggestion on that?</DIV>
<DIV> </DIV>
<DIV>I attached the LST file and the plot for the chiller water temp. I
really appreciate any help.</DIV>
<DIV> </DIV>
<DIV>Best regards,</DIV>
<DIV> </DIV>
<DIV>Billy</DIV><!-- end sanitized html -->
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