Chemical Engineering - Heat Transfer
Exercise :: Heat Transfer - Section 4
| 1. |
The critical radius 'r' of insulation on a pipe is given by |
| A. |
r = 2k/h | | B. |
r = k/h | | C. |
r = k/2h | | D. |
r = h/k |
Answer: Option B
Explanation:
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| 2. |
As per Kirchoffs law, the ratio of the total radiating power to the absorptivity of a body depends on the |
| A. |
temperature of the body only. | | B. |
wavelength of monochromatic radiation. | | C. |
both (a) and (b). | | D. |
nature of material of body. |
Answer: Option A
Explanation:
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| 3. |
If the baffle spacing in a shell and tube heat exchanger increases, then the Reynolds number of the shell side fluid |
| A. |
remains unchanged. | | B. |
increases. | | C. |
increases or decreases depending on number of shell passes. | | D. |
decreases. |
Answer: Option D
Explanation:
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| 4. |
The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by |
| A. |
painting the surface black. | | B. |
painting the surface white (with aluminium paint). | | C. |
giving the surface a mirror finish. | | D. |
roughening the surface. |
Answer: Option B
Explanation:
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| 5. |
__________ paint has the maximum absorption coefficient. |
Answer: Option A
Explanation:
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