[Bldg-sim] TRANSFER FUNCTION FOR HEAVY AND THICK WALLS

Luis Miguel Blanes Restoy lmblanes at gmail.com
Fri May 16 06:37:47 PDT 2014


Luis

You may explore E+ different ways of dealing with CTF (state space method
mainly). CTF calculations become unstable for short time steps and massive
constructions (it is at the end a computational problem). E-Quest may
decide on your arrangement to be unstable before running the simulation
(not sure of this). There are solutions to solve this problem (Seem 1987),
and I guess these have been incorporated into CTF calculation within E+. It
is a matter of giving E+ a go and try out if your example may work there.

E+ also handles Finite Differences Methods for CTF calculations, but I am
not versed in this field.

You can find more information in the E+ Engineering Reference Manual.

Regards
Abrazos desde Hibernia
Luis




2014-05-16 14:06 GMT+01:00 Luis Peréz-Lombard <lpl at us.es>:

>  Dear colleagues,
>
>
>
> As you probably know, Conduction Transfer Function (CTF) method does not
> handle thick and massive walls, because the accuracy of the CTF
> coefficients is degraded. In particular, in DOE-2, you get the following
> message:
>
>
>
> *“Cannot simulate LAYERS …….. as given. The wall is too thick or too
> dense”*
>
>
>
> I have heard of a possible solution to solve this problem by dividing the
> wall into thin layers. I have made an attempt in e-quest, but the problem
> remains, and I do not know how to proceed.
>
>
>
> Any insight on this issue would be appreciated.
>
> Sincerely,
>
> LPL
> -------------------------------------------------------------
> Luis Pérez-Lombard
> Dr. Ingeniero Industrial
> Profesor Contratado Doctor
> Departamento de Ingeniería Energética
> Escuela Superior de Ingenieros
> Universidad de Sevilla
> Camino de los Descubrimientos s/n
> 41092 SEVILLA
> Tfno.:      95.448.72.56
> Fax:         95.446.31.53
> e-mail:    lpl at us.es
> -------------------------------------------------------------
>
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-- 
LUIS M BLANES RESTOY

*IRUSE *INFORMATICS RESEARCH UNIT FOR SUSTAINABLE ENGINEERING
www.iruse.ie
 mobile Ireland: +353 83 1346875
mobile Spain: +34 609097818
skype: lmblanes
email: lmblanes at gmail.com
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