Abstract
Louvers blind can change its surrounding airflow and temperature field, which will affect the convective heat transfer of a vertical surface near louvers. In order to correctly predict HVAC load and building energy consumption, it is important to calculate the convective heat transfer coefficient of interior and exterior surfaces with louvers. The present study has been conducted on a CFD simulation for laminar and steady natural convective heat transfer in an approximated system that consists of an isothermal vertical surface with louvers blind. The effects of louvers blind on the natural heat transfer are obtained by the two-dimensional CFD model, which is validated with the previous experimental data. It is found that the louvers can promote or restrain the natural convective heat transfer of an isothermal surface. Such effects are periodic distributed along the vertical direction, which is partially determined by the geometry and physical properties of louvers. The impact of distance from louvers to surface b, temperature difference between surface and ambient air ΔT as well as louvers angle φ on the heat transfer coefficient distribution will be discussed in this research.
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- b :
-
Distance from louvers to surface
- w :
-
Width of louver blade
- t:
-
Thickness of louver blade
- p :
-
Blade spacing
- u, v :
-
x, y velocity components
- g :
-
Gravitational acceleration
- c p :
-
Specific heat
- k :
-
Thermal conductivity
- I :
-
Radiation intensity
- F kj :
-
View factor from surface k to surface j
- A :
-
Surface area for radiation calculation
- r :
-
Distance from surface k to surface j
- h :
-
Convective heat transfer coefficient
- \( \varphi \) :
-
Louvers angle, degrees
- ρ :
-
Density
- μ :
-
Dynamic viscosity
- β :
-
Volumetric expansion coefficient
- T :
-
Temperature
- ε :
-
Emissivity
- σ :
-
Stefan-Boltzmann constant
- \( \infty \) :
-
Associated with ambient air
- s :
-
Associated with the isothermal surface
- b :
-
Associated with blinds
- l :
-
Associated with local heat transfer
References
Fang X, Ge X (1993) Experimental study of overall heat transfer coefficients of a window with venetian blinds. J Solar Energy 14(2):138–141 (in Chinese)
Machin AD, Naylor D, Harrison SJ, Oosthuizen PH (1998) Experimental study of free convection at an indoor glazing surface with a venetian blind. Int J HVAC&R Res 4(2):153–166
Phillips J (1999) Numerical study of the effects of venetian blinds on radiation and convection heat transfer from a window glazing. M.E.Sc.Thesis, University of Western Ontario, London, Ontario, Canada
Shahid H, Naylor D (2005) Energy performance assessment of a window with horizontal Venetian blinds. Energy Build 37:836–843
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© 2014 Springer-Verlag Berlin Heidelberg
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Jiang, F., Li, Z., Zhao, Q., Tao, Q., Li, X. (2014). A CFD Study of Convective Heat Transfer at an Isothermal Surface with Horizontal Louvers. In: Li, A., Zhu, Y., Li, Y. (eds) Proceedings of the 8th International Symposium on Heating, Ventilation and Air Conditioning. Lecture Notes in Electrical Engineering, vol 263. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-39578-9_19
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DOI: https://doi.org/10.1007/978-3-642-39578-9_19
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Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-39577-2
Online ISBN: 978-3-642-39578-9
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