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MCQs

Total Questions : 70 | Page 3 of 7 pages
Question 21. Logarithmic mean area of the cylindrical tube is given as
  1.    2πrm
  2.    πrml
  3.    2πrml
  4.    2rml
 Discuss Question
Answer: Option C. -> 2πrml
Answer: (c).2πrml
Question 22. The heat flow equation through a cylinder of inner radius r1 and outer radius r2 is desired to be written in the same form as that for heat flow through a plane wall. For wall thickness (r₂-r₁) the area will be
  1.    A1 + A2/2
  2.    A1 + A2
  3.    A2 – A1/ log e (A2/A1)
  4.    A1 + A2/2 log e (A2/A1)
 Discuss Question
Answer: Option A. -> A1 + A2/2
Answer: (a).A1 + A2/2
Question 23. A cylinder of radius r and made of material of thermal conductivity k 1 is surrounded by a cylindrical shell of inner radius r and outer radius 2r. This outer shell is made of a material of thermal conductivity k 2. Net conductivity would be
  1.    k 1 + 3 k 2/4
  2.    k 1 + k 2/4
  3.    k 1 + 3k 2
  4.    k 1 + k 2
 Discuss Question
Answer: Option A. -> k 1 + 3 k 2/4
Answer: (a).k 1 + 3 k 2/4
Question 24. For steady state and constant value of thermal conductivity, the temperature distribution associated with radial convection through a cylinder is
  1.    Linear
  2.    Parabolic
  3.    Logarithmic
  4.    Exponential
 Discuss Question
Answer: Option C. -> Logarithmic
Answer: (c).Logarithmic
Question 25. A hot fluid is being conveyed through a long pipe of 4 cm outer diameter and covered with 2 cm thick insulation. It is proposed to reduce the conduction heat loss to the surroundings to one-third of the present rate by further covering with same insulation. Calculate the additional thickness of insulation
  1.    11 cm
  2.    12 cm
  3.    13 cm
  4.    14 cm
 Discuss Question
Answer: Option B. -> 12 cm
Answer: (b).12 cm
Question 26. The following data pertains to a hollow cylinder and a hollow sphere made of same material and having the same temperature drop over the wall thickness
Inside radius = 0.1 m and outside surface area = 1 square meter
If the outside radius for both the geometrics is same, calculate the ratio of heat flow in the cylinder to that of sphere?
  1.    0.056
  2.    2.345
  3.    1.756
  4.    3.543
 Discuss Question
Answer: Option C. -> 1.756
Answer: (c).1.756
Question 27. For a prescribed temperature difference, bodies with the same shape factor will allow heat conduction proportional to
  1.    k/2
  2.    2k
  3.    k
  4.    k/4
 Discuss Question
Answer: Option C. -> k
Answer: (c).k
Question 28. Shape factor for cylinder is
  1.    6 π l/log e (r₂/r₁)
  2.    4 π l/log e (r₂/r₁)
  3.    π l/log e (r₂/r₁)
  4.    2 π l/log e (r₂/r₁)
 Discuss Question
Answer: Option D. -> 2 π l/log e (r₂/r₁)
Answer: (d).2 π l/log e (r₂/r₁)
Question 29. Shape factor for plane wall is equal to
  1.    A/δ
  2.    2A/δ
  3.    3A/δ
  4.    4A/δ
 Discuss Question
Answer: Option A. -> A/δ
Answer: (a).A/δ
Question 30. “All the factors relating to geometry of the sections are grouped together into a multiple constant called the shape factor” True or false
  1.    True
  2.    False
  3.    May be
  4.    Can't say
 Discuss Question
Answer: Option B. -> False
Answer: (b).False

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