Abstract
The effect of the surface thermal radiation in tall cavities with turbulent natural convection regime was analyzed and quantified numerically. The parameters considered were: the Rayleigh number 109–1012, the aspect ratio 20, 40 and 80 and the emmisivity 0.0–1.0. The percentage contribution of the radiative surface to the total heat transfer has a maximum value of 15.19% (Ra = 109, A = 20) with emissivity equal to 1.0 and a minimum of 0.5% (Ra = 1012, A = 80) with ε* = 0.2. The average radiative Nusselt number for a fixed emissivity is independent of the Rayleigh number, but for a fixed Rayleigh number diminishes with the increase of the aspect ratio. The results indicate that the surface thermal radiation does not modify significantly the flow pattern in the cavity, just negligible effects in the bottom and top of the cavity were observed. Two different temperature patterns were observed a conductive regime Ra = 109 and a boundary layer regime Ra = 1012.
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Abbreviations
- A :
-
aspect ratio (H/L)
- C p :
-
specific heat, J kg−1 K−1
- C 1ε , C 2ε , C 3ε , C μ :
-
constants of the turbulence model
- dF Aj–Ak :
-
view factor between elements j–k
- g :
-
gravitational acceleration, 9.81 m s−2
- G k :
-
buoyancy production/destruction of kinetic energy
- H :
-
height of the cavity, m
- k :
-
turbulence kinetic energy, m2 s−2
- L :
-
length of the cavity, m
- Nu :
-
Nusselt number
- P :
-
pressure, Pa
- P K :
-
turbulence kinetic energy production
- q :
-
heat flux, W m−2
- Ra :
-
Rayleigh number, (gβΔTH 3 /να)
- T :
-
temperature, K
- T*:
-
non-dimensional temperature, (T – T c )/ΔT
- u O :
-
reference velocity, (gβΔTH)0.5 m s−1
- u :
-
horizontal velocity component, m s−1
- u*:
-
non-dimensional horizontal velocity, u/u O
- v :
-
vertical velocity component, m s−1
- v*:
-
non-dimensional vertical velocity, v/u O
- x :
-
horizontal coordinate, m
- x*:
-
non-dimensional horizontal coordinate, x/H
- y :
-
vertical coordinate, m
- y*:
-
non-dimensional vertical coordinate, y/H
- α :
-
thermal diffusivity, m2 s−1
- β :
-
thermal expansion coefficient, K−1
- ΔT :
-
temperature difference, (T h – T c ) K
- ε :
-
rate of disipation of k
- ε*:
-
emissivity
- λ :
-
thermal conductivity, W m−1 K−1
- μ :
-
dynamic viscosity, kg m−1 s−1
- μ t :
-
turbulent viscosity, kg m−1 s−1
- ν :
-
kinematic viscosity, m2 s−1
- ρ :
-
density, kg m−3
- σ :
-
Stefan–Boltzmann Constant, W m−2 K−4
- c:
-
cold wall
- conv:
-
convective
- h:
-
tot wall
- max:
-
maximum
- mean:
-
average
- min:
-
minimum
- rad:
-
radiative
- total:
-
total quantities
References
Faggembauu D, Costa M, Soria M, Oliva A (2003) Numerical analysis of the thermal behaviour of ventilated glazed facades in Mediterranean climates. Part I: development and validation of a numerical model. Solar Energy 75:217–228
Faggembauu D, Costa M, Soria M, Oliva A (2003) Numerical analysis of the thermal behaviour of ventilated glazed facades in Mediterranean climates. Part II: applications and analysis of results. Solar Energy 75:229–239
Soria M, Costa M, Schweiger H, Oliva A (1998) Design of multifunctional ventilated façades for Mediterranean climates using a specific numerical simulation code. Euro Sun 2 1:2.25–1
Todorovic B, Cvjetkovic T (2000) Double building envelopes: consequences on energy demand for heating and cooling. In: Proceedings of the IV international building installation science and technology symposium, Istanbul, vol 1. pp 17–19
Gratia E, De Herde A (2004) Optimal operation of a south double-skin façade. Energy Build 36:41–60
Balocco C (2002) A simple model to study ventilated façades energy performance. Energy Build 34:469–475
Balocco C (2004) A non-dimensional analysis of a ventilated double façade energy performance. Energy Build 36:35–40
Von Grabe J (2002) A prediction tool for the temperature field of double façades. Energy Build 34:891–899
Manz H (2003) Numerical simulation of heat transfer by natural convection in cavities of façade elements. Energy Build 35:305–311
Xamán J, Álvarez G, Lira L, Estrada C (2005) Numerical study of heat transfer by laminar and turbulent natural convection in tall cavities of facade elements. Energy Build 37:787–794
Velusamy K, Sundararajan T, Seetharamu K (2001) Interaction effects between surface radiation and turbulent natural convection in square and rectangular enclosures. J Heat Transf 123:1062–1070
Manz H (2004) Total solar energy transmittance of glass double façades with free convection. Energy Build 36:127–136
Daffa’alla A; Betts P (1991) Experimental study for turbulent natural convection in a tall air cavity. Report TFD/91/6. UMIST, UK
Ince N, Launder B (1989) On the computation of buoyancy-driven turbulent flows in rectangular enclosures. Int J Heat Fluid Flow 10:110–117
Siegel R, Howell JR (2001) Thermal radiation heat transfer. Taylor and Francis, New York
Patankar S (1980) Numerical heat transfer and fluid flow. Hemisphere, Washington
Van Doormaal J, Raithby G (1984) Enhancements of the SIMPLE method for predicting incompressible fluid flow. Numer Heat Transf 7:147–163
Betts PL, Bokhari IH (2000) Experiments on turbulent natural convection in an enclosed tall cavity. Int J Heat Fluid Flow 21:675–683
Pérez-Segarra CD, Oliva A, Costa M, Escanes F (1995) Numerical experiments in turbulent natural and mixed convection in internal flows. Int J Num Meth Heat Fluid Flow 5:13–33
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Xamán, J.P., Hinojosa, J.F., Flores, J.J. et al. Effect of the surface thermal radiation on turbulent natural convection in tall cavities of façade elements. Heat Mass Transfer 45, 177–185 (2008). https://doi.org/10.1007/s00231-008-0393-5
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DOI: https://doi.org/10.1007/s00231-008-0393-5