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An exhaust fan attached to an evasee of 18 m2 cross-sectional area at the outlet circulates 150 m3/s of air at the pressure of 1000 Pa in a mine ventilation system. The ratio of the inlet to outlet area of the evasee is 1 : 4 and the density of air is 1.2 kg/m3. The quantity of air circulated in the mine in absence of evasee is 120 m3/s. The eva see efficiency in % is

An exhaust fan attached to an evasee of 18 m2 cross-sectional area at the outlet circulates 150 m3/s of air at the pressure of 1000 Pa in a mine ventilation system. The ratio of the inlet to outlet area of the evasee is 1 : 4 and the density of air is 1.2 kg/m3. The quantity of air circulated in the mine in absence of evasee is 120 m3/s. The eva see efficiency in % is Correct Answer 57.6

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