Heat Transfer

351. The driving potential for the crystal growth during crystallisation is the _________ of the solution.

1. Concentration
2. Viscosity
3. Super-saturation
4. Density

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352. The energy radiated from a surface Q at absolute temperature T is related as

1. Q ∝ t₂
2. Q ∝ T4
3. Q ∝ T3
4. None of these

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353. The equation, (N_St × N^2/3 _Pr) = f/2, is the _________ analogy.

1. Colburn
2. Reynolds
3. Prandtl
4. None of these

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354. The equation, N_st = ƒ/2, is the _________ analogy.

1. Colburn
2. Reynolds
3. Prandtl
4. None of these

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355. The equation, N_st = (f/2)/[1 + 5 (N_pr - 1) √(f/2)], corresponds to _________ analogy.

1. Von-Karman
2. Reynolds
3. Colburn
4. Prandtl

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356. The equivalent diameter for pressure drop is _________ that for heat transfer.

1. Smaller than
2. Greater than
3. Equal to
4. Not related with

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357. The equivalent diameter for the annulus of a double pipe heat exchanger, whose inner pipe has fins on the outside is _________ compared to the same size pipes without fins.

1. More
2. Less
3. Same
4. Unpredictable

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358. The film co-efficient between condensing vapour and metal wall increases with

1. Increasing temperature of the vapour
2. Decreasing temperature of the vapour
3. Increasing viscosity of the film of condensate
4. Increasing temperature drop

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359. The film co-efficient is decreased due to the presence of non-condensing gases in the vapors. The film co-efficient of superheated vapor as compared to that of saturated vapor is

1. More
2. Less
3. Some
4. Either more or less; depends on the nature of vapor

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360. The film thickness for laminar film condensation on vertical surface _________ from top to bottom.

1. Cumulatively increases
2. Cumulatively decreases
3. Remain constant
4. And the surface conductance increase

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