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

[francesca lorusso via TRNSYS-users]

Dear Oriol,

I am using the same type for the same reason and i have a lot of doubts on
coil hx's geometry, i suppose that cross section area is: coil height*coil
diameter, even if i am not sure that is right, the tank works. I list all
my hypothesis below, to compare with yours:
Coil pitch= the distance center to center between two tubes;
Coil diameter= i choose the diameter of the tank, because i don't have
information about coil diameter;
Number of tubes= one single tube coiled;
Length= number of circumferences*pi*coil diameter;
where the number of circumferences=heat transfer surface (from data sheet
of tank) / (pi*coil_diameter*pi*tube_diameter)
coil height=number of circumferences*coil pitch + tube diameter;

For miscellaneous flows i set zero, because i ve only auxiliary heaters....
i think your hypothesis is right.

Do you agree with me?
if you have any other suggestion, please tell me.

Best regards,
Francesca lorusso

2017-03-03 11:19 GMT+01:00 Oriol Casal via TRNSYS-users <
trnsys-users at lists.onebuilding.org>:

> 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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>
>


-- 
*FRANCESCA LORUSSO*
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