Re: [TRNSYS-users] Front side Boundary condition

[David BRADLEY <d.bradley@tess-inc.com>]

Luis,
 I think the idea is that Type56 is calculating the effects of what happens in the zone being modeled. The front side of the wall is inside the zone so Type56 is going to calculate the air temperature, the wall surface temperature, and (if you allow it to) the convection coefficient between the air and wall. If you are trying to model a surface in your zone that is always at some known temperature then I think you are correct that the best way to model it would be to specify a back-side temperature in direct contact with a low-mass "wall." I would allow Type56 to calculate the convection coefficient between your surface and the zone air temperature since this convection coefficient is dependent on both the magnitude and the "direction" of the temperature difference.
Best,
 David


On 8/2/2011 03:47, Claros Marfil, Luis Jesus wrote:

Hi Trnsys Users,

I would like to know if it is possible to define a boundary value for the FRONT SIDE of a wall directly. In page 6-103 (Type 56 - TRNSYS 16 Manual) it is said that : ”Normally, the boundary condition is the temperature of a node connected to the back surface of the wall through a pure resistance. It is possible to specify the surface temperature of the outside by setting the back side heat transfer coefficient of the WALL TYPE to a very small value (less than 0.001 kJ/h/m2).

So, I understand that if a coefficient with a value of  0,001 kJ/h/m2 or lower is used, the boundary temperature corresponds to the back side, and the only way I find to “transform” this back side temperature into a front side temperature is using a very-low resistance (massless layer) by using a high convective heat transfer coefficient in the front side.

Any idea would be highly appreciated.

Thanks, 

Luis J. Claros Marfil
Grupo de Materiales Avanzados - Advanced Materials Group
Centro Tecnológico I+D+i  - R & D Technology Center
ACCIONA Infraestructuras
	Valportillo II, nº8 C.P. 28108 Alcobendas (Madrid) Tel.: +34  91 791 20 20 Fax: +34  91 791 21 01                                                                                         www.acciona-infraestructuras.es

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