Radiation Heat Transfer Coefficient for a Gray Surface

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This Demonstration studies the relationship between the radiation heat transfer coefficient and the temperature at the surface of the object and the temperature of the surroundings (idealized as an isothermal enclosing surface that is much larger than the object).


You can vary the emissivity and the temperature . For a "gray" surface, the incident radiation is reflected, absorbed, and transmitted to varying degrees. This can be parametrized in terms of the emissivity, in the range .


Contributed by: Cibele V. Falkenberg (February 2016)
Open content licensed under CC BY-NC-SA



The radiation heat transfer coefficient is given by , where is the Stefan–Boltzmann constant ().

This Demonstration can be used to compare the value obtained for with the range of values for the convective heat transfer coefficient for air when subject to free and forced convection. Notice the importance of emissivity, which is dependent on the surface material.


[1] T. L. Bergman, A. S. Lavine, F. P. Incropera, and D. P. Dewitt, Fundamentals of Heat and Mass Transfer, 7th ed., Hoboken, NJ: Wiley, 2011.

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