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<p><span lang="EN-GB">Christopher,</span></p>
<p><span lang="EN-GB"> As a side note, it may be worth considering
the nature of the models that you are using in your simulation
as you think about using very short timesteps. Some (many)
TRNSYS models are quasi steady state meaning that their outputs
react immediately to input value changes and that they don't
necessarily explicitly model the transition from one state to
the next. For a pump or a heat exchanger that is a perfectly
reasonable assumption if you are using a timestep that is long
in comparison to the transient effect. However, if you shorten
your simulation timestep down to some very very small value then
those assumptions are perhaps not so good anymore. It may take
more than 5s for a large pump to start and come up to steady
flow and a heat exchanger might have enough internal thermal
mass that the outlet's don't react to inlet temperature changes
until a few timesteps later.</span></p>
<p><span lang="EN-GB">kind regards,</span></p>
<p><span lang="EN-GB"> David</span></p>
<p><span lang="EN-GB"> <br>
</span></p>
<div class="moz-cite-prefix">On 02/11/2022 04:21, Graf, Christopher
via TRNSYS-users wrote:<br>
</div>
<blockquote type="cite"
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<p class="MsoNormal"><span lang="EN-GB">Dear Trnsys users,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">as part of my research I
simulated a building with domestic hot water (DHW) and space
heating system for one year. My current time step is 3min
(0.05hr). I’m thinking about lowering the time step to
improve the resolution of my DHW tapping profiles and the
simulation results. <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">I wondered if I can
basically take any time step? For example if I choose to
take 5s (0.13</span><!--[if gte msEquation 12]><m:oMath><m:acc><m:accPr><m:chr m:val="̅"/><span style='font-family:"Cambria Math",serif'><m:ctrlPr></m:ctrlPr></span></m:accPr><m:e><span lang=EN-GB><m:r><m:rPr><m:nor/></m:rPr>8</m:r></span></m:e></m:acc></m:oMath><![endif]--><!--[if !msEquation]--><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;position:relative;top:2.5pt;mso-text-raise:-2.5pt;mso-fareast-language:EN-US"><img
style="width:.0729in;height:.177in" id="_x0000_i1025"
src="cid:part1.yLGZIXjy.7lUgKPp8@tess-inc.com" class=""
width="7" height="17"></span><!--[endif]--><span
lang="EN-GB"> or rounded 0.13888889) it technically adds up
to 8760 hr, but in reality the time steps needs to rounded
after a certain number of decimals, true? Will the time step
be rounded in TRNSYS? And if yes, h</span><span lang="EN-GB">ow
does TRNSYS cope with a time step which does not exactly add
up to 8760 hr? Does it make a difference whether I chose to
“min” or “s” instead of “hr” during the configuration of the
time step in the settings menu?
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Therefore, would it be
best or is it necessary to choose a time steps which is
discrete and adds up to 8760 hr?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Thank you for your
answers!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Best Regards, <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Christopher Graf<o:p></o:p></span></p>
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<p class="MsoNormal" style="border:none;padding:0cm"><b><span
style="color:#7F7F7F;mso-fareast-language:DE"><o:p> </o:p></span></b></p>
</div>
<p class="MsoNormal"><span
style="font-size:10.0pt;color:#7F7F7F;mso-fareast-language:DE"
lang="EN-GB"><br>
Christopher Graf, M.Sc.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;color:#7F7F7F;mso-fareast-language:DE"
lang="EN-GB">Scientific Associate, PhD-Candidate<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;color:#7F7F7F;mso-fareast-language:DE"
lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;color:#7F7F7F;mso-fareast-language:DE"
lang="EN-GB">Thermal Energy System Departement, Energy
Economics and Process Integration Division<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;color:#7F7F7F;mso-fareast-language:DE"
lang="EN-GB">Fraunhofer Institute for Energy Economics and
Energy System Technology<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;color:#7F7F7F;mso-fareast-language:DE"
lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:10.0pt;color:#7F7F7F;mso-fareast-language:DE"
lang="EN-GB">Gottschalkstr. 28a | 34127 Kassel | Germany
(Visiting adress)<o:p></o:p></span></p>
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style="font-size:10.0pt;color:#7F7F7F;mso-fareast-language:DE">Königstor
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<p class="MsoNormal"><span
style="font-size:10.0pt;color:#7F7F7F;mso-fareast-language:DE"><a
href="mailto:christopher.graf@iee.fraunhofer.de"
moz-do-not-send="true"><span style="color:#7F7F7F"
lang="EN-GB">christopher.graf@iee.fraunhofer.de</span></a></span><span
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<pre class="moz-signature" cols="72">--
***************************
David BRADLEY
Principal
Thermal Energy System Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI 53703 USA
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