Dear Friends
My team and I are working on simulation of a solar chimney. Using Solar chimney is a way to have a passive ventilation or producing power electricity. Solar Chimney contains a duct which covers with glass and have an absorb plate to get radiation heat flux from the sun.This plate warms the inlet air by natural convection.By this method the air goes forward to top of the duct. Using this method could help you to ventilate rooms of a building which connected to this chimney or produce power electricity. The problem is choosing suitable absorb plate. In a lot of studies scientists choose Aluminum plate as absorb plate. Does any body know a better absorb plate.The other question is what's scattering coefficient and absorption coefficient for Aluminum as a solid and Air as a fluid in this special study ?
For more information I attached some pictures of solar chimney
Best Regards
all figures reported in the literature are only true for the conditions of the particular site and experiments!
I believe you are seeking the absorptivity / emissivity of the coated aluminum plate. You might try Kennedy's "Review of Mid- to High-Temperature Solar Selective Absorber Materials." You shouldn't need the absorption / scattering coefficient of the air unless you are modeling the radiative transfer between the plate and the fluid—I wouldn't think it was significant in the context of home heating applications.
Dear Philip
Thanks for your kindly answer.
I knew the absorptivity and emissivity of the aluminum plate and the glazing ( I mean the glass which covers my collector ) . but we have some parts to fill in the Boundary condition like scattering coefficient and absorption coefficient and these are different from absorptivity and emissivity. I found that the scattering coefficient and absorption coefficient for the clean air is about zero. But the thing I don't know yet is that is it necessary to define absorption coefficient and scattering coefficient for solids like the glass of collector or aluminum or not.
thanks a lot for your kindly attention
Best Regards
No need. Absorption / scattering coefficients apply to radiation passing through a semi-transparent medium (which would have some degree of absorption) with some dispersed interacting particles of differing index of refraction (which would have some degree of absorption and scattering). The glazing and absorber can be modeled with surface properties--i.e., emissivity, reflectivity, etc.
The scattering coefficient for a semi-transparent medium is zero, however, the absorption coefficient is a function of the wavelength, for example:
for solar spectrum a= 10 1 / m...
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