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Re: [TRNSYS-users] Problem in creating a new wall type



The u-value shown in TRNBuild is based on the wall materials but also includes an assumed combined heat transfer coefficient to the inside and outside surfaces (7.7W/m2.K inside and 25 W/m2.K outside). The value is only for display purposes because Type56 calculates the inner and outer convection and radiation heat transfer coefficients internally as a function of time as the simulation progresses. There is an NTYPE among the outputs if you want to know what the actual (time dependent) u-value of the wall is.
Kind regards,
 David


At 09:30 3/15/2007, Issa Jaffal wrote:
Dear All
When i was trying to make a new wall type in the wall type manager; i
couldnt explain how the Uvalue in the wall type manager is calculated,
for istance:

if i make a wall with a single layer of 0.1 m of Concrete  U-value =
4.595 and if i make a wall with a single layer of 0.2 m of Concrete
(same layer type)  U-value=3.770 but normaly the U-value will be devided
by 2 if i double the thikness form 0.1 to 0.2!!!

I tried to change the values of convective heat transfert coefficient
but  the Uvalue didnt change:

So how we can explain theses values the U-value ?

Regards
Issa JAFFAL
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