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:
|
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:
|
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:
|
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:
|
5. |
__________ paint has the maximum absorption coefficient. |
Answer: Option A
Explanation:
|