engleski

Cooling of sphere due to natural convection - a test of lumped model approach

The cooling of the hot sphere immersed in initially quiescent fluid is technically relevant problem. The three approaches for prediction of time variation of the sphere temperature and heat transfer rate between the sphere and the fluid are compared. The first approach is based on solving of the full mathematical model by means of commercial CFD software. The second approach is based on lumped model and Churchill's correlation function for the heat transfer coefficient which is solved using Runge-Kutta method. The third approach is based on further simplification of the lumped parameter model by assuming a constant heat transfer coefficient so the analytical solution can be obtained. It is concluded that in the considered case the second approach, which is considerably cheaper than the first approach offers results reasonably close to the results of the first approach. In the case when the rate of cooling is of interest the third approach is not a good choice.

cooling of sphere; lumped model; natural convection; heat transfer correlation

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