[TRNSYS-users] U-value of a wall

Enertech sidler at club-internet.fr
Wed Nov 2 06:37:57 PST 2005


Dear TRNSYS Users,

When defining a new wall, TRNBUILD calculates a standard U-value determined 
with combined heat transfer coefficients of 7.7 W/m²K inside and 25 W/m²K 
outside (see volume 6 page 23). These U-values are correct for a vertical 
wall separating an inside environnement from an outside environnement, but 
not for horizontal walls and inside vertical walls. Does TRNBUILD take 
these distinctions into account or does it use these two standard 
coefficients (7 and 25) for every wall types ?

A second question in relation with the first one : combined heat transfer 
coefficients normally takes into account superficial convective and 
radiative heat transfers. So wich coefficients are used in calculations ? 
standard combined coefficients ? Convective heat transfer coefficients of 
wall defined in the wall type manager ? Both ?

Regards,
Christophe.


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ENERTECH
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Email : sidler at club-internet.fr
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