[TRNSYS-users] modelling differences of Type 56 between BOUNDARY=INTERNAL and BOUNDARY=IDENTICAL

[Marion Hiller]

Dear TRNSYS-Users,

In this news group a question concerning modelling differences of Type 56 between the following option of an opaque surface was posted:

  1.  BOUNDARY=INTERNAL
  2.  BOUNDARY=IDENTICAL

Both options yield to the exact same results

  *   if the surface construction type is defined symmetrically
(symmetric layer composition, solar absorption front = solar absorption back, IR emissivity front = IR emissivity back, heat transfer coefficient front = heat transfer coefficient solar absorption back)
  *   if the a) is defined a single surface with double area and b) is defines as two surfaces with half the area:

                      WALL         =REFEND_TERRE_CRUE : SURF=  3 : AREA=         2 : INTERNAL

WALL         =REFEND_TERRE_CRUE : SURF=  5 : AREA=         1 : BOUNDARY=IDENTICAL
WALL         =REFEND_TERRE_CRUE : SURF=  6 : AREA=         1 : BOUNDARY=IDENTICAL

The reason for this is that Type56 splits the INTERNAL surface (a) into 2 equivalent surfaces with half the area.

We recommend to use the option "BOUNDARY=IDENTICAL" because

  *   the users enters directly what is modelled (no hidden rearrangement)
  *   it can be used  for 3D geometry

The option "BOUNDARY=IDENTICAL" is kept up to now for "historical reasons".
It is under consideration to drop this option.

Marion

-----------------------------------------------------------------------------------------------------------------------------------------------------------
Dipl.-Ing. Marion Hiller
TRANSSOLAR Energietechnik GmbH
Stuttgart - Munich - New York - Paris
t: +49.711.67976.0<tel:%2B49.711.67976.27>   f: +49.711.67976.11<tel:%2B49.711.67976.11>
www.transsolar.com/<http://www.transsolar.com/>

KlimaEngineering - Technologien für energieeffizientes Bauen und Nutzerkomfort in Gebäuden
Transsolar Energietechnik GmbH, Curiestrasse 2, 70563 Stuttgart
Amtsgericht Stuttgart - HRB 23347 / Steuernummer: 99073/00911 / USt-IdNr.: DE 152272639
Geschäftsführer: Matthias Schuler, Thomas Auer, Stefan Holst, Dieter Schnelle


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