Question

Two flowstreams of water, one at 0.6 MPa, saturated vapor, and the other at 0.6 MPa, 600°C, mix adiabatically in a steady flow process to produce a single flow out at 0.6 MPa, 400°C. Find the total entropy generation for this process.  

Answer 1

h₁ = 2756.8 kJ/kg, s₁ = 6.760 kJ/kg K

h₂ = 3700.9 kJ/kg, s2 = 8.2674 kJ/kg K

h3 = 3270.3 kJ/kg, s3 = 7.7078 kJ/kg K 

The mixing process generates entropy. The two inlet flows could have exchanged energy (they have different T) through some heat engines and produced work, the process failed to do that, thus irreversible.