Naslov
Cooling of a sphere by natural convection – the applicability of the lumped capacitance method

Autori
Virag, Zdravko ; Živić, Marija ; Krizmanić, Severino

Izvornik
International journal of heat and mass transfer (0017-9310) 54 (2011), 11/12; 2303-2309

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
sphere cooling; natural convection; lumped capacitance method

Sažetak
Two approaches to predicting the sphere cooling process by laminar natural convection were compared in terms of the accuracy of the volume averaged sphere temperature and the heat transfer rate between the sphere and the surrounding fluid. The first approach is based on the formulation of conjugate heat transfer (heat conduction in the sphere and laminar natural convection in the fluid). The second approach included the lumped capacitance method based on the assumption that the temperature in the sphere is spatially uniform and on the Churchill correlation function. The solution to the problem depends on the Rayleigh number (Ra), the Biot number (Bi), the Prandtl number (Pr), and the sphere-to-fluid thermal diffusivity ratio (A). The lumped capacitance method gives fairly accurate results with respect to the conjugate heat transfer method (discrepancy in the volume averaged sphere temperature less than 5%) when A*Bi/Ra**0.452<0.05 for Bi<0.15 and Pr>1.

Izvorni jezik
Engleski

Znanstvena područja
Strojarstvo

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