Im working on some problem for a chemical thermodynamics course, and ive solved a question (maybe incorrectly) which is making me question my understanding of entropy. Basically, the system in question is a turbine, with one stream in and one stream out. The turbine is insulated, hence no heat transfer occurs. The system is also in a steady state. Because the system is in steady state, the rate of change of entropy within the system should be zero -- Am i right in saying this? Also, since there is no heat transferred to the surroundings, the entropy change here should also be zero? This would imply that the total entropy generation in the universe due to this process is zero? Now that is a nice simple answer, however in the way i understand the second law of thermodynamics, entropy change will only be zero if a process is carried out reversibly. Does the result above imply that the process was carried out reversibly? Or have i missed something in calculating the entropy generation of the universe? Thanks in advance, Dan.