Summary
Thermal free convection from a sphere has been studied by melting solid benzene spheres in excess liquid benzene (Pr=8,3; 108<Gr<109). Overall heat transfer as well as local heat transfer were investigated. For the effect of cold liquid produced by the melting a correction has been applied. Results are compared with those obtained by other workers who used alternative experimental methods.
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Abbreviations
- α :
-
coefficient of heat transfer
- d :
-
characteristic length, here diameter of sphere
- λ :
-
thermal conductivity
- g :
-
acceleration of free fall
- β :
-
cubic expansion coefficient
- ΔT :
-
temperature difference between wall and fluid at infinity
- ν :
-
kinematic viscosity
- ρ :
-
density
- c :
-
specific heat capacity
- a :
-
thermal diffusivity (=λ/ρc)
- D :
-
diffusion coefficient
- Nu :
-
dimensionless Nusselt number (=αd/λ)
- Nu*:
-
the analogous number for mass transfer (=kd/D)
- \(\overline {Nu} \) :
-
mean value of Nusselt number
- Gr :
-
dimensionless Grashof number (=gβd 3ΔT/ν 2)
- Gr*:
-
the analogous number for mass transfer (=gβd 3Δx/ν 2)
- Pr :
-
dimensionless Prandtl number (=ν/a)
- Sc :
-
dimensionless Schmidt number (=ν/D)
References
Dumoré, J. M., H. J. Merk and J. A. Prins, Nature 172 (1953) 460; Van der Burgh, J., Appl. sci. Res. A 9 (1960) 293; Frederikse, J. W., unpublished work.
Schütz, G., Int. J. Heat Mass Transfer 6 (1963) 873.
Garner, F. H. and R. B. Keey, Chem. Engng Sci. 9 (1959) 218. Garner, F. H. and J. M. Hoffman, A.I.Ch. E. J. 7 (1961) 148.
Merk, H. J. and J. A. Prins, Appl. sci. Res. A 4 (1954) 207 (particularly fig. 4).
Merk, H. J., Appl. sci. Res. A 4 (1954) 435.
Kranse, A. A., Internal report, Technische Hogeschool Delft 1965. Contains the complete experimental material that could not be presented in full in fig. 1 and 2 of this paper.
Pei, D. C. T. and W. H. Gauvin, A.I.Ch. E. J. 9 (1963) 375.
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Kranse, A.A., Schenk, J. Thermal free convection from a solid sphere. Appl. sci. Res. 15, 397–403 (1966). https://doi.org/10.1007/BF00411573
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DOI: https://doi.org/10.1007/BF00411573