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Today's Topics:
1. Re: The necessity of using pipes in TRNSYS models (Ben Heymer)
2. Question about windows properties.. (Arnaud Candaele)
---------- Forwarded message ----------
From: Ben Heymer <bheymer@gmail.com>
To: "TRNSYS users mailing list at OneBuilding.org" <trnsys-users@lists.onebuilding.org>
Cc:
Date: Tue, 24 Jun 2014 09:17:17 -0500
Subject: Re: [TRNSYS-users] The necessity of using pipes in TRNSYS models
Amir,
Yes, you should include pipes in the loop with at least enough volume
to handle the flow during one timestep. If you think this volume is
unrealistically high, reduce your time step. You can set the thermal
losses of the pipes to zero if you choose.
I sometimes use an equation to define the minimum pipe length to avoid
convergence errors as I explore a model. If you define your time step
as a global parameter, you can use something like:
minpipelength = 1.1 * pipeflow (m^3/hr) * timestep (hr) / pipearea (m2)
pipelength = max(minpipelength, realpipelength)
-Ben Heymer
On Tue, Jun 24, 2014 at 8:50 AM, Amir Nashed <nashed.amir@gmail.com> wrote:
> Dear TRNSYS users
>
> I am currently trying to model an application using solar collectors to heat
> water and i realized that when i put pipes in the solar collector loop, i
> get strange output water temperatures (very low values).
>
> So what i did is that i isolated the solar collector loop and modeled it by
> itself and the same problem occurs unless i use very small pipes in terms of
> size.
>
> But if i used a small pipe size i sometimes get the warning that the flow
> rate the pipe during at least one component was greater than the capacity of
> the pipe.
>
> has anyone faced trouble with the pipes before? And is using pipes in the
> model needed from the first place in terms of the model stability?
>
> Thank you
>
>
>
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---------- Forwarded message ----------
From: Arnaud Candaele <arnaud.candaele@gmail.com>
To: trnsys-users@cae.wisc.edu
Cc:
Date: Tue, 24 Jun 2014 16:34:57 +0200
Subject: [TRNSYS-users] Question about windows properties..Any help would be greatly appreciated ! I've been looking in WINDOW manual, as wel in the TRNSYS manuals, I can't find anything in there...==> which one of these area is actually used in TRNSYS computation?Also, which window is on the interior side, and which one on the exterior side (1st or second column ?) ?I just want to be sure of what that means : I guess "F" and "B" are for "front" and "back", but which of these sides is actually towards the interior of the building ?Emis B 0.840 0.840Emis F 0.840 0.060My question is regarding the Emissivity properties that can be read :I'm using a window type in a building simulation, and for this I choose a window from the library "/American/w4-lib", ID 2306. Thiw window type has 2 layers of glass separated by a layer of gas.Hi all,I know this kind of question has already been asked, but I can't seem to find a complete answer, so here it is again, maybe someone can help :
I think that for exterior walls, TRNSYS uses "back" to describe the "outer" face of the wall (outside). But I also read somewhere (..) that for instance "Rfsol" (so "front" reflectance) in the window description is also for the exterior facing side of the window.. In the end, I don't know if "front" is supposed to mean "interior facing side" or "exterior facing side".
Also, in the window description, there are dimensions (width, height). In the Window Type Manager, there are also dimensions taht you can enter ("For 1 glazing module", just below "slope of window"). Finally, in the different zones of my building where I actually use this type of window, there is an area which correspond to the area of the window I drew in sketchup.
Thanks ,Arnaud.
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