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Re: [TRNSYS-users] Wind loss modeling

John,
We have recently published the results of our CFD investigation of external convective heat transfer coefficients:
M. Emmel, M.O. Abadie, N. Mendes, New external convective heat transfer coefficient correlations for isolated low-rise buildings, Energy and Buildings (39)3: 335-342, 2007
You will find in this article expressions for vertical walls and roof that take into account the wind velocity and direction. 

Regards,

-- Marc O. Abadie
Visiting researcher at Pontifical Catholic University of Parana ? PUCPR/CCET/Thermal Systems Laboratory - LST - Curitiba ? Brazil 
Associate Professor at LEPTAB - University of La Rochelle, France




Quoting David Bradley <bradley@tess-inc.com>:


John,
  Most of the building models in TRNSYS simply ask for the user to
supply the external heat transfer coefficient so you can treat it
however you like. The algorithm that I usually use is from ASRHAE:

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

where h is the external convection coefficient in kJ/h.m2, AA, BB, and
CC are empirical coefficients that depend on the exterior surface
material and WindVel is the wind speed in m/s. The AA, BB and CC
coefficients (again 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

Cheers,
 David


At 13:30 9/12/2007, J.A. Palyvos wrote:

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Dear all,
I would appreciate any information on the external forced convection algorithms (i.e. wind loss coefficient expressions) used in TRNSYS.(I am aware of the McAdams/Jurges linear relation used in Type 19). 

Many thanks,

J.A. Palyvos, NTUA
Athens

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