Heat Transfer

211. In a shell and tube heat exchanger, the tube side heat transfer co-efficient just at the entrance of the tube is

  1. Infinity
  2. Zero
  3. Same as average heat transfer co-efficient for tube side
  4. None of these
Correct answer: (A)
Infinity

212. In a shell and tube type heat exchanger, the floating tube bundle heat arrangement is used

  1. In low range of temperature differences
  2. In high range of temperature differences
  3. Because of its low cost
  4. To prevent corrosion of the tube bundles
Correct answer: (B)
In high range of temperature differences

213. In a single effect evaporator, the economy is

  1. 1
  2. < 1
  3. > 1
  4. None of these
Correct answer: (B)
< 1

214. In a single evaporator system, the steam economy _________ by creating vacuum in the evaporator.

  1. Increases
  2. Decreases
  3. Remain constant
  4. May increase or decrease, depends on the vacuum
Correct answer: (A)
Increases

215. In an extended surface heat exchanger, fluid having lower co-efficient

  1. Flows through the tube
  2. Flows outside the tubes
  3. Can flow either inside or outside the tubes
  4. Should not be used as it gives very high pressure drop
Correct answer: (B)
Flows outside the tubes

216. In an interphase heat transfer process, the equilibrium state corresponds to equality of temperature in the two phases, while the condition for equilibrium in an interphase mass transfer process is equality of

  1. Concentrations
  2. Chemical potentials
  3. Activity co-efficients
  4. Mass transfer co-efficients
Correct answer: (A)
Concentrations

217. In Biot number, the characteristic length used is the ratio of the _________ of the solid.

  1. Volume to surface area
  2. Perimeter to surface area
  3. Surface area to volume
  4. Surface area to perimeter
Correct answer: (A)
Volume to surface area

218. In case of _________ boiling, the bubbles formed on a submerged hot surface get absorbed in the mass of the liquid.

  1. Nucleate
  2. Pool
  3. Low pressure
  4. None of these
Correct answer: (B)
Pool

219. In case of _________ boiling, the liquid temperature is below the saturation temperature and the boiling takes place in the vicinity of the heated surface.

  1. Nucleate
  2. Local
  3. Pool
  4. Saturated
Correct answer: (B)
Local

220. In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side _________ the heat transfer rate.

  1. Increases
  2. Decreases
  3. Does not affect
  4. May increase or decrease, depends on the type of baffle
Correct answer: (A)
Increases
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