Re: [TRNSYS-users] PCM storage tank modeling

[Ben Heymer <bheymer@gmail.com>]

Yosr,

I have done this study before (though probably a simpler version than
what you have in mind). I assumed fixed thermal properties for the PCM
(best case scenario), then compared it to the heat storage
capabilities of a "dumb" water tank of the same size with a
temperature controlled mixing valve.

I initially considered modifying an existing component to incorporate
temperature dependence, but I never made it past the simplified model
because the water tank always performed better (in terms of fluid
temperature control). I found that the relatively poor thermal
conductivity of the PCM severely limited any benefit of phase change
for my application. Though the water doesn't change phase, it is very
cheap, the specific heat capacity is high, and the heat exchange
effectiveness is 100%.

I hope your study is more interesting.

Ben Heymer, PE


On Tue, Oct 28, 2014 at 9:51 AM, Yosr ALLOUCHE <allouche.yosr@gmail.com> wrote:
> Dear All,
>
> I am a Trnsys 17 user, I want to model vertical storage tank containing
> coils as heat exchanger. My tank fluid is a phase change material that has
> temperature-dependent thermal properties ( specific heat, thermal
> conductivity, density and viscosity)
> at this moment the closest type that could describe my case is the type
> 534-coiled from TESS library, the only thing is that this type only
> considers fixed thermal properties( not temperature dependent).
>
> Does any one have an idea in how to model temperature dependence properties?
>
> Many thanks
>
> Best regards
>
> --
>  Yosr ALLOUCHE
> Energy Engineer / PhD Student
>
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users@lists.onebuilding.org
> http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org
>