Heat Transfer-1 (color)

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$X-ray, Neutron and Electron Diffraction of Crystals Scope and Use of ...$

• In metals, the free electron mechanism of heat transport is much more efficient than the phonon mechanism, because phonons are more easily scattered than free electrons and electrons ahave higher velocities. • Thermal energy associated with phonons is transported in the direction of their motion (net movement of phonons from high to low temperature regions) • Free electrons in hot regions have higher kinetic energy tham these in cold regions. When they migrate to colder regions, their kinetic energy is transferred to atoms as vibrational energy (collision of electrons with phonons). • Thermal conductivities of common pure metals or alloys range from 20 to ca. 400 W.m -1 .K -1 . When impurities are are present in a metal or alloying is used, the impurity atoms act as scattering centers for the electrons, decreasing the efficiency of electron motion (i.e. k e)
• In ceramics k e
Page 1 and 2: Materials Engineering Science MESc.
Page 3 and 4: - Heat Transfer via Free Electrons:
Page 5: • In most solids, the principal m
Page 9 and 10: Kinetic Theory of Gases: assumes id
Page 11 and 12: Example Calculation #1 • Steam is
Page 13 and 14: Example Calculation #2 • For stea
Page 15 and 16: • Regardless of the flow phenomen
Page 17 and 18: Example Calculations #3 Given the s

Heat Transfer-1 (color)

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