A reduction in thermal resistance during heat transfer does not occur in the___________________?
Correct answer: D. Radiation heat transfer by increasing the temperature and reducing the emissivity
- A. Convection heat transfer by stirring the fluid and cleaning the heating surface
- B. Conduction heat transfer by reduction in the material thickness and increase in the thermal
- C. conductivity
- D. Radiation heat transfer by increasing the temperature and reducing the emissivity
- E. None of these
Explanation
For radiation, lowering emissivity lowers the radiation heat-transfer coefficient and increases thermal resistance, so it does not produce a reduction in resistance. Stirring, cleaning surfaces, reducing thickness and increasing conductivity all reduce resistance in their respective modes.
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