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<p><span style="font-family: 宋体; font-size: large;">Weihua,</span></p>
<p><span style="font-family: 宋体; font-size: large;"> First, if you
are using Trnsys18 then I would recommend that you work your way
through some of the tutorials that are in the 09-Tutorials.pdf
(..\Trnsys18\Documentation). There are a lot of issues in your
email that are very fundamental to the correct use of Trnsys and
that would be worth understanding well.</span></p>
<p><span style="font-family: 宋体; font-size: large;"> The warnings
that you refer to are probably warnings about timesteps when the
simulated system did not converge. TRNSYS has a limit so that if
more than a certain number of warnings are generated, the
simulation will terminate with an error. You can adjust the
allowable number of warnings before the error but I would not
recommend you do so; non convergence issues should be corrected.
<br>
</span></p>
<p><span style="font-family: 宋体; font-size: large;"> It is hard to
tell you how to solve convergence problems; it depends on what
you're simulating. The usual problems are that you do not have
any enough thermal mass in the loops of a system. For instance
if you have a Type1 solar collector, pump and heat exchanger
model in a loop then those are all quasi steady state models and
there is no thermal mass. The models will react unrealistically
fast to external changes and may result in convergence problems.
The other typical problem is too long a time step. Trnsys can
only make one control decision per time step. If you are
controlling a system with a 1 hour time step then the system
will likely be unstable and have problems converging. I
recommend using something between a 1 and 5 minute timestep.</span></p>
<p><span style="font-family: 宋体; font-size: large;"> For your
question about the active layer I would recommend that you refer
to the Type56 manual to understand the limitations on the model.</span></p>
<p><span style="font-family: 宋体; font-size: large;">kind regards,</span></p>
<p><span style="font-family: 宋体; font-size: large;"> David</span></p>
<p><span style="font-family: 宋体; font-size: large;"> <br>
</span></p>
<br>
<div class="moz-cite-prefix">On 08/08/2018 19:48, 吕伟华 via
TRNSYS-users wrote:<br>
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<div style=" ; ; ;; "><font style="line-height: 30.6px;"
size="4" face="宋体">hello,I am student, I use TRNSYS to do
some simulation works. I have some confusion during my work.</font><span
style="font-family: 宋体; font-size: large;"> I conducted a
simulation system of a new air conditioning system on the
pletform of TRNSYS. the type56 was used to build the
building model and the active layer was used to simulate the
pipe-embedded wall.</span></div>
<div style=" ; ; ;; "><span style="font-family: 宋体; font-size:
large;">My questions are:</span></div>
<div style=" ; ; ;; "><span style="font-family: 宋体; font-size:
large;">1) I have built the simualtion model and it can run
successfully. but when I change the weather data from one
city to another city, and change the envelope insulation(U
value), other things keep the same. then I ran the
simulation again, it began to work, but after a period
running, it breaked and the message shows that"the maximum
number of warnings allowed per simulation has been
exceeded". I donnot know why. Can you explain this situation
for me? and how should i do ?</span><span
style="font-family: 宋体; font-size: large;"> </span></div>
<div style=" ; ; ;; "><font style="line-height: 30.6px;"
size="4" face="宋体">2) similarly, in some simulation, when I
set the timestep one hour, it can run successfully, but if I
set the time step 30 minutes, or less time, it began to run
but then occur the same error as </font><span
style="font-family: 宋体; font-size: large;">"the maximum
number of warnings allowed per simulation has been
exceeded". can you help me with this question?</span></div>
<div style=" ; ; ;; "><span style="font-family: 宋体; font-size:
large;">3) for the parameter of the active layer,when I
change the pipe wall conductivity value,the allowed minimum
water flow will change. the default value is 0.792kJ/hmk，if
i change this value to 1.56 </span><span
style="font-family: 宋体; font-size: large;">kJ/hmk, </span><span
style="font-family: 宋体; font-size: large;">the allowed
minimum water flow willincrease, bigger than 13 kg/h.m2.
what is the relation between the pipe wall conductivity and
the water flow rate? can you help me with this phenomenon?</span><span
style="font-family: 宋体; font-size: large;"> </span></div>
<div style=" ; ; ;; "><span style="font-family: 宋体; font-size:
large;"> looking forword for your reply. many thanks!</span></div>
<div style=" ; ; ;; "><span style="font-family: 宋体; font-size:
large;">Best wishes!</span></div>
<div style=" ; ; ;; "><span style="font-family: 宋体; font-size:
large;">Weihua</span></div>
</div>
<div><span style="font-family: 宋体; font-size: large;"><br>
</span></div>
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<pre class="moz-signature" cols="72">--
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
3 North Pinckney Street - suite 202
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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