[TRNSYS-users] TRNSYS-users Digest, Vol 114, Issue 20

[Amir Nashed]

Hi Ben

Thank you so much for your answer, it helped a lot

Best Regards,
Amir


On Wed, Jun 25, 2014 at 6:11 AM, <trnsys-users-request at lists.onebuilding.org
> wrote:

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>    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 at gmail.com>
> To: "TRNSYS users mailing list at OneBuilding.org" <
> trnsys-users at 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 at 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 at gmail.com>
> To: trnsys-users at cae.wisc.edu
> Cc:
> Date: Tue, 24 Jun 2014 16:34:57 +0200
> Subject: [TRNSYS-users] Question about windows properties..
> 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'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.
>
> My question is regarding the Emissivity properties that can be read :
>
> Emis F   0.840 0.060
> Emis B   0.840 0.840
>
> 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 ?
> Also, which window is on the interior side, and which one on the exterior
> side (1st or second column ?) ?
>
> 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.
>
> ==> which one of these area is actually used in TRNSYS computation?
>
> 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...
>
> Thanks ,
>
> Arnaud.
>
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