Mass Transfer - Study Mode

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[#556] The percentage humidity is less than the relative humidity only at __________ percent humidity.

(A) Zero

(B) Hundred

(C) Both zero and hundred

(D) None of these

Correct Answer

(C) Both zero and hundred

[#557] Unsaturated air (with dry bulb temperature and dew point being 35°C and 18°C respectively) is passed through a water spray chamber maintained at 15°C. The air will be cooled

(A) And humidified

(B) And dehumidified with increase in wet bulb temperature

(C) At the same relative humidity

(D) And dehumidified with decrease in wet bulb temperature

Correct Answer

(D) And dehumidified with decrease in wet bulb temperature

[#558] At equilibrium the concentration of water in vapour phase (C * ) in kg/m 3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C * = 0.0667 m. To maintain dry conditions in a room of air space 100 m 3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is

(A) 0.0

(B) 0.2

(C) 0.4

(D) 1.0

Correct Answer

(C) 0.4

[#559] In a forced draft cooling tower, water is cooled from 95 to 80°F by exposure to air with a wet bulb temperature of 70°F. In this case, the

(A) Range is 15°F

(B) Approach is 10°F

(C) Both A & B

(D) Neither A nor B

Correct Answer

(C) Both A & B

[#560] During sensible cooling process

(A) Relative humidity decreases

(B) Relative humidity increases

(C) Wet bulb temperature decreases

(D) Both B and C

Correct Answer

(D) Both B and C