Influence of convective heat transfer coefficient on the heating rate of materials with different thermal diffusivities
2006
Palazoglu, K.
Thermal diffusivity is an important thermophysical property affecting the heating rate of objects. It is common knowledge that an object with a higher thermal diffusivity will always heat faster in comparison to that with a lower thermal diffusivity. This study was undertaken to demonstrate numerically and experimentally that this is not always true. To accomplish this, a finite difference model was developed, and temperature changes at the surface and geometric center of cubic particles of different thermophysical properties were obtained for different convective heat transfer coefficient values (50 and 1000 W/m2 K). Experiments were also performed with potato and polymethylpentene cubic particles in still water and boiling water to obtain their heating rates under different heating conditions. The study showed that individual effects of the heat storage (rhoc(p)) and heat conduction (k) terms play an important role in determining the heating rate of an object, and that depending on the h value, a particle with a lower thermal diffusivity may heat faster than a particle with a higher thermal diffusivity. Therefore, it is not really possible to say which object will heat faster without knowing the heat transfer coefficient.
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