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Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning - Discussion

Discussion Forum : Heat Transfer, Refrigeration and Air Conditioning - Section 2 (Q.No. 19)
Heat Transfer, Refrigeration and Air Conditioning
19.
Which of the following would lead to a reduction in thermal resistance?
In conduction, reduction in the thickness of the material and an increase in thermal conductivity.
In convection, stirring of the fluid and cleaning the heating surface.
In radiation, increasing the temperature and reducing the emissivity.
all of the above
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
9 comments Page 1 of 1.
VIKRANT said:   1 decade ago
Reducing the emissivity will increase thermal resistance.
Om Nagar said:   8 years ago
Agree @Vikrant.
Lekha said:   8 years ago
How is it? Please explain.
Lekha said:   8 years ago
How emissivity decreses resistance?
Angesh said:   7 years ago
Resistance to radiation Inversely proportional to emissivity according to Wein's law.
Shankar said:   7 years ago
Can you explain how option C statement also correct?
Sukhdeep Singh said:   7 years ago
Reducing the emmisivity will increase the thermal resistance. For example, black body has least thermal resistance because its emmisivity is unity. As we reduce the emmisivity the heat transfer will reduce due to radiation hence increasing thermal resistance. So, the answer should be A and B only.
Biswajit said:   6 years ago
BECAUSE r(radiation) = 1-e/eA, So if e increases are decreases.
Vinay said:   5 years ago
Reducing the emissivity will increase thermal resistance.
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