Lakshya Education MCQs

Question: The average heat transfer co-efficient for laminar film condensation on vertical surface is inversely proportional to (where, ΔT = Temperature drop across condensate film )
Options:
A.(ΔT)2
B.√ΔT
C.(ΔT)1/4
D.(ΔT)3/2
Answer: Option C

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More Questions on This Topic :

Question 1. Multiple effect evaporators ar used to
  1.    Increase the steam economy & decrease the capacity
  2.    Increase the steam economy & the capacity
  3.    Decrease the steam economy & the capacity
  4.    Decrease the steam economy & increase the capacity
Answer: Option B
Question 2. Pick out the wrong statement.
  1.    The condensing film co-efficient is about 3 times lower for vertical condenser as compared to the equivalent horizontal condenser for identical situation
  2.    Film co-efficient for vaporisation decreases as a result of vapor binding
  3.    In industrial practice, sub-cooling of condensate is required, when the condensate is a volatile liquid and is to be transferred for storage
  4.    Overall heat transfer co-efficient in a heat exchanger is controlled by the value of the film co-efficient, which is higher
Answer: Option D
Question 3. Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because
  1.    Convection becomes important
  2.    Conduction becomes important
  3.    Radiation becomes important
  4.    Sub-cooled boiling occurs
Answer: Option C
Question 4. Tube pitch is the __________ of tube diameters and the clearances.
  1.    Sum
  2.    Difference
  3.    Ratio
  4.    None of these
Answer: Option A
Question 5. In a shell and tube heat exchanger, the height of 25 percent cut baffles is equal to (where, D = inside diameter of shell)
  1.    0.25 D
  2.    0.75 D
  3.    0.50 D
  4.    None of these
Answer: Option B
Question 6. For heat flow through very thick walled cylinder, use____mean radius.
  1.    Arithmetic
  2.    Logarithmic
  3.    Geometric
  4.    Either A or C
Answer: Option B

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