Question

A stream of moist air (mass flow rate = 10.1 kg/s) with humidity ratio of 0.01 kg/kg dry air mixes with a second stream of superheated water vapour flowing at 0.1 kg/s. Assuming proper and uniform mixing with no condensation, the humidity ratio of the final stream (in kg/kg dry air) is __________.

Accepted Answer

The correct answer is 0.02 (± 0.001). Stream 1's dry-air mass ≈ 10.1/1.01 = 10.0 kg/s, water-vapour mass = 0.1 kg/s. Stream 2 is pure water vapour (0.1 kg/s), contributing no dry air. Total water vapour = 0.1+0.1 = 0.2 kg/s; total dry air = 10.0 kg/s (unchanged). New humidity ratio = 0.2/10.0 = 0.02 kg/kg dry air.

Explanation