Heat Transfer MCQ Questions & Answers

81

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

A) More B) Less C) Some D) Either more or less ; depends on the nature of vapor

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Answer & Solution

Answer: Option C

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82

Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 kcal/hr.m².°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the

A) Higher condensing film co-efficient is desired B) Condensate is corrosive in nature C) Lower pressure drop through the exchanger is desired D) Temperature of the incoming vapor is very high

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Answer & Solution

Answer: Option B

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83

If a single tube pass heat exchanger is converted to two pass, then for the same flow rate, the pressure drop per unit length in tube side will

A) Increase by 1.8 times B) Decrease by 22 C) Increase by 216 D) Remain unchanged

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Answer & Solution

Answer: Option C

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84

The thermal radiation emitted by a body is proportional to Tⁿ, where T is its absolute temperature. The value of 'n' is exactly 4 for

A) Black painted bodies only B) All bodies C) Polished bodies only D) A black body

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Answer & Solution

Answer: Option B

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85

Convective heat transfer, in which heat is transferred by movement of warmed matter is described by

A) Fourier's law B) Newton's law of cooling C) Fick's law D) None of these

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Answer & Solution

Answer: Option B

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86

Viscosity of gases __________ with increase in temperature.

A) Increase very rapidly B) Increase slowly C) Decrease slowly D) Remain unaffected

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Answer & Solution

Answer: Option B

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87

Thermal conductivity of a gas at low density, __________ with increase in temperature.

A) Decreases B) Increases C) Remains unchanged D) May increase or decrease; depends on the gas

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Answer & Solution

Answer: Option B

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88

The Sieder-Tate correlation for heat transfer in turbulent flow in pipe gives Nu α Re^0.8, where, Nu is the Nusselt number and Re is the Reynolds number for the flow. Assuming that this relation is valid, the heat transfer co-efficient varies with the pipe diameter (D) as

A) (D)^-1.8 B) (D)^-0.2 C) (D)^0.2 D) (D)^1.8

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Answer & Solution

Answer: Option B

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89

Pick out the wrong statement.

A) Heat transfer by radiation can not occur across an absolute volume B) In case of a shell and tube heat exchanger, the pressure drop through the shell is proportional to the number of times the fluid crosses the bundle between baffles C) Propagation velocity for travel of heat radiation through vacuum is equal to the velocity of the light D) The amount of heat involved in the condensation or vaporisation of 1 kg of a fluid is the same

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Answer & Solution

Answer: Option A

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90

According to Reynolds analogy, Stanton number is equal to (where, f = Fanning friction factor)

A) 2f B) f C) $$\frac{{\text{f}}}{2}$$ D) $$\frac{{\text{f}}}{4}$$

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Answer & Solution

Answer: Option C

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Heat Transfer MCQ Questions & Answers | Chemical Engineering