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

[David Bradley]

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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Thermal Energy System Specialists (TESS), LLC
David BRADLEY                           2916 Marketplace Drive - Suite 104
Partner                                        Madison, WI 53719
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