It is necessary to dilute hydrogen gas by mixing it with nitrogen. Assume the mixing is done in a steady flow adiabatic mixer. The ratio of mixing is 2 kmol of hydrogen for every kmole of nitrogen.

The hydrogen enters the mixer at 20 C and 500 kPa, while the nitrogen enters at 200 C and 500 kPa.

At the exit of the mixture a single stream of mixture leaves at 490 kPa. Determine the temperature of the exit mixture and the entropy change associated with the mixing (per kmole of mixture). Assume ideal gas behavior and constant specific heats with cp H2 = 28.6 kJ/(kmole-K), cpN2 = 29.4 kJ/(kmoleK).

Ans. 354K, 6.22 kJ/(K-kmole)