Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning

11.
For evaporators and condensers, for the given conditions, the logarithmic mean temperature difference (tm) for parallel flow is __________ that for counter flow.
equal to
less than
greater than
Answer: Option
Explanation:
No answer description is available. Let's discuss.

12.
A vapour absorption refrigerator uses __________ as a refrigerant.
water
ammonia
freon
aqua-ammonia
Answer: Option
Explanation:
No answer description is available. Let's discuss.

13.
Thermal conductivity of air increases with rise in temperature.
Correct
Incorrect
Answer: Option
Explanation:
No answer description is available. Let's discuss.

14.
The material of pipe lines for a system using ammonia as a refrigerant should be copper.
Yes
No
Answer: Option
Explanation:
No answer description is available. Let's discuss.

15.
The wave length corresponding to the maximum energy is inversely proportional to the absolute temperature. This statement is called Planck's law.
Yes
No
Answer: Option
Explanation:
No answer description is available. Let's discuss.