Engineering Flow and Heat Exchange pp 209241  Cite as
UnsteadyState Heating and Cooling of Solid Objects
Chapter
Abstract
If a hot object is plunged into cold water it cools, but not instantaneously. Two factors govern the cooling rate of the object:

the film resistance at the surface of the object, characterized by the h value for that situation; and
 The rate of heat flow out of the interior of the object. The governing differential equation for this conduction process iswhere$$\frac{\partial T_{s}}{\partial t} = \alpha \left ( \frac{\partial^{2}T_{s}}{\partial x^{2}} + \frac{\partial^{2}T_{s}}{\partial y^{2}} + \frac{\partial^{2}T_{s}}{\partial z^{2}}\right )$$(11.1)and$$\alpha = \frac{k_{s}}{\rho_{s}C_{s}},\;\;\;\;\textup{thermal\;diffusivity}\;[\textup{m}^{2}/\textup{s}]$$$$T_{s} = \textup{temperature\;at\;any\;point\;in\;the\;object}\;\;[\textup{K}]$$
Keywords
Surface Resistance Biot Number Solid Object Fourier Number Roasted Peanut
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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References and Notes
 L. M. K. Boelter V. H. Cherry, H. A. Johnson, and R. C. Martinelli, Heat Transfer Notes, McGrawHill, New York (1956). Gives detailed derivations of the many equations for unsteady state conduction used in this chapter.Google Scholar
 M. Colakyan, R. Turton, and O. Levenspiel, Unsteadystate transfer to various shaped objects, Heat Transfer Engineering 5, 82 (1984).CrossRefGoogle Scholar
 H. Gröber, S. Erk, and U. Gringull, Fundamentals of Heat Transfer (translated from the German by J. R. Moszynski), McGrawHill, New York (1961). Also a good source book for many of the underlying equations of this chapter.Google Scholar
 H. P. Gurney and J. Lurie, Charts for estimating temperature distributions in heating and cooling solid shapes, Ind. Eng. Chem. 15, 1170 (1923).CrossRefGoogle Scholar
 J. Mator, M. S. Project, Chemical Engineering Department, Oregon State University, Corvallis (1982).Google Scholar
 A. Schack, Industrial Heat Transfer (translated from the 6th German ed., by I. Gutman), Wiley, New York (1965).Google Scholar
 J. Sucec, Heat Transfer, Simon and Schuster, New York (1975).Google Scholar
 J. R. Welty, Engineering Heat Transfer, p. 135, Wiley, New York (1974).Google Scholar
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© Springer Science+Business Media New York 1998