Estimate the amount of moisture evaporated per hour, assuming that the block of ice is perfectly insulated except for the surface exposed to the air stream.

 

A.    Predict the mass transfer coefficient for liquid ammonia vaporising into air at 1 atm, 25°C, knowing that the heat transfer coefficient in the same equipment, at the same gas and

liquid flow rates, is 4.544 kW/m2 K.

 

B.    Dry air at 25°C and atmospheric pressure blows over a 30 cm2 surface of ice at a velocity of 1.5 m/s. Estimate the amount of moisture evaporated per hour, assuming that the block of ice is perfectly insulated except for the surface exposed to the air stream.