To maintain a pressure close to atmosphere,
an industrial pipeline containing ammonia gas is vented to ambient air. Venting
is achieved by tapping the pipe and inserting a 3 mm diameter tube, which
extends for 20 m into the atmosphere. With the entire system operating at 25°C,
determine the mass rate at which ammonia is lost to the atmosphere and the mass
rate of contamination of the pipe with air. What are the mole and mass
fractions of air in the pipe when the ammonia flow rate is 5 kg/h. Given: For
ammonia-air system at 298 K, D = 0.28 10–4 m2/s.