[TRNSYS-users] Convection heat transfer coefficients

[Diego A. Arias]

Dear Elena,

You can find the default values for the calculation of the convection 
coefficients in the PROPERTIES section of the .inf file:

*  P r o p e r t i e s
*--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
PROPERTIES
 DENSITY=0.987 : CAPACITY=1.012 : HVAPOR=2454.0 : SIGMA=2.041e-007 : 
RTEMP=293.15
*--- alpha calculation -------------------
 KFLOORUP=7.2 : EFLOORUP=0.31 : KFLOORDOWN=3.888 : EFLOORDOWN=0.31
 KCEILUP=7.2 : ECEILUP=0.31 : KCEILDOWN=3.888 : ECEILDOWN=0.31
 KVERTICAL=5.76 : EVERTICAL=0.3

where the heat transfer coefficient ALPHA is calculated as:
ALPHA_i = K_i /3.6 * abs(T_surface - T_air)^(E_i)

If you want, you can look at the source code of Type56 for the 
calculation of the heat transfer coefficients 
(\SourceCode\Type56\OpenSouce\Open_TYPE56.for). This is done in the  
subroutine CALHTC.
I hope this helps.
Best regards,

Diego



Dascalaki Elena wrote:

> Dear TRNSYS Users
>  
> Using TRNSYS16 for the calculation of convection coefficients of the 
> internal wall surfaces in a very simple building model, I realized 
> that I get different results when I use the "internal calculation" 
> facility in the wall typemanager menu and when I use Type 80. Could 
> you please explain to me where the difference in the two ways of 
> calculation process lies?
> I would also like to know where I could find the reference for the 
> values of the default coefficients and exponents that are 
> incorporated in TRNSYS16. In the Manuals, the default coefficients 
> given in TRNSYS16 electronic user's manual (page 65) and in Vol.6 
> (paper verion of the manual for Type 56) the default values seem to be 
> slightly different.
>  
> Thank you in advance,
> Elena Dascalaki  
>
> *********************************************************************************************************
> Dr. Elena Dascalaki
> Building Physicist
> Group Energy Conservation (G.R.E.C.)
> Institute for Environmental Research and Sustainable Development (IERSD)
> National Observatory of Athens (NOA)
> I. Metaxa & Vas. Pavlou, GR 152 36, Penteli, Greece
>  
> Tel:  +30 210 810 9143
> Fax: +30 210 810 3236
>  
> e-mail: edask at meteo.noa.gr <mailto:edask at meteo.noa.gr>
> web site: www.noa.gr <http://www.noa.gr>
>
>------------------------------------------------------------------------
>
>_______________________________________________
>TRNSYS-users mailing list
>TRNSYS-users at engr.wisc.edu
>https://www.cae.wisc.edu/mailman/listinfo/trnsys-users
>  
>


-- 

Diego A. Arias
TRNSYS Coordinator
Solar Energy Laboratory
University of Wisconsin - Madison
1500 Engineering Drive
Madison, WI 53706