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Zorluk: OrtaHeat Transfer: Radiation

A dull, dark-colored machinery housing will dissipate internal heat through thermal radiation faster than an identical housing with a highly polished, light-colored finish, assuming both are at the same operating temperature.

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The statement is true.
Dark, dull surfaces are excellent emitters of thermal radiation due to their high emissivity. As a result, they dissipate internal heat into the surrounding environment much faster than highly polished surfaces, which have low emissivity and act as poor radiators.

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1
Identify the mode of heat transfer being tested.
The scenario focuses entirely on thermal radiation as the method of dissipating internal heat.
Understanding the heat transfer method determines which material properties are relevant to the problem.
2
Evaluate the effect of surface finish on thermal radiation.
Dark, dull surfaces have high emissivity, while shiny, light-colored surfaces have low emissivity.
Emissivity is the physical measure of a material's effectiveness in emitting thermal energy as electromagnetic radiation.
3
Determine which housing dissipates heat faster.
The dull, dark-colored housing will radiate heat faster than the polished housing.
A higher emissivity value means thermal energy is radiated away from the object at a significantly greater rate.

Anahtar Kavram

Surface Emissivity and Thermal Radiation
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Konular

Heat Transfer: Radiation

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