[TRNSYS-users] TRNSYS Type 534 doubt cross sectional area and temperature-dependent properties

Oriol Casal via TRNSYS-users trnsys-users at lists.onebuilding.org
Fri Mar 3 02:19:13 PST 2017


Dear all,

I am currently working on a hot sanitary water system with a solar
collector and a storage tank, and I have chosen Type 534 for the tank
because it seemed to be able to cover all my modeling needs.

However I have not found much information on a couple of topics: If I use
the version without the plug-in I cannot choose Propylene Glycol as a fluid
and instead I have to input a single value for the physical properties. Is
there a way to not use the plug-in and be able to have time-dependent
properties?

Furthermore, I have struggled a lot to try to grasp what "HX
cross-sectional area" is, I have finally decided that for the coil HX case
it must be pi*(CoilPipeOuterRadius-CoilPipeInnerRadius)^2, however the
default value from TRNSYS is quite higher (two orders of magnitude higher),
is my interpretation correct? I have also found other default values to be
far away from the ones that I am using, such as the HX wall conductivity,
which is two orders of magnitude lower than I would expect, does this mean
I should not be using TRNSYS default values for those parameters I have no
information on? (such as heat transfer phenomena inside the coil).

Finally, I have set miscellanous flows to zero, despite not being entirely
sure of what they are, I suppossed they would only be used in case of
external energy flows, but instead, in order to do that I am using the
auxiliary gains.

Kind regards,

O.C.
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