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Re: [TRNSYS-users] Convection heat transfer coefficients
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@meteo.noa.gr <mailto:edask@meteo.noa.gr>
web site: www.noa.gr <http://www.noa.gr>
------------------------------------------------------------------------
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Diego A. Arias
TRNSYS Coordinator
Solar Energy Laboratory
University of Wisconsin - Madison
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