Re: [TRNSYS-users] Type 56- Restaurant's example

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

Meriem,

> 1- In type 56, When you
> calculate the response factors of the walls, which properties do you take
> for the inside and the outside air layers?? Do you take the ASHRAE
> standard library (I mean the layer A0 for the outside surface resistance
> and the layer E0 for the inside surface resistance).
> How does this interfeer with the indicated values of
> (hc)int?

The convection and radiation from the inside and outside surfaces of
Type56 walls are calculated internally based on the user specified values
of front side and back side solar absorptance and inside and outside
convection coefficient. These values are specified in the wall type
manager in TRNBuild. TRNBuild displays a wall u-value that includes
estimated values of front and back side surface resistance but these
values are for display only. The actual values are calculated during the
simulation and are a function of current ambient conditions. 

> 2-How to calculate response
> factors with variable values of convective heat transfer coefficient of
> wall (inputs/shedule values)??

in order to see the time dependent, calculated values of the wall
u-value, you need to choose the appropriate Type56 output NTYPE by
clicking on the "outputs" button in the TRNBuild project
window.

> 3-In the example
> "Restaurant" ; the convective heat transfer coefficient
> (back)of the wall  "outside" is defined as = 1*HOUTSIDE;
> where HOUTSIDE is an input of type 56, and HOUTSIDE is not connected to
> any other type, that means that during the simulations, this parameter is
> equal to zero?? Why is that input not connected
> properly??

you are quite correct; that is an error in the example. There should be
an equation that sets the value of HOUTSIDE and that equation should be
connected to Type56's input. The equation should have the form:

(AA+BB*WindVel+CC*WindVel**2)*3.6

where AA, BB, and CC are empirical coefficients that depend on the
exterior surface material and WindVel is the wind speed. The AA, BB and
CC coefficients (from ASHRAE) would be:

        

        

        

AA

      

BB

      

CC
Stucco

  

        

11.58

   

5.894

   

0.0
Brick

   

        

        

12.49

   

4.065

   

0.028
Concrete

        

        

10.79

   

4.192

   

0.0
Wood

    

        

        

8.23

    

4.00

    

-0.057
Smooth
plaster

  

10.22

   

3.1

     

0.0
Glass

   

        

        

8.23

    

3.33

    

-0.036

Thanks for finding that error.
David



>  
>  
>     Thank you for clarifying my doubts.
>  
>  
>      Best regards
>      Meriem
>      
>
>
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