Lost Work and Entropy Generation

Work and heat are exchanged with the environment while a fluid is brought from condition 1 at P 7) to condition 2 at P2, T2. 

AH and AS express the changes in the flow s enthalpy and entropy from state 1 to state 2, for example, 

The minimum amount of work to accomplish this change in conditions is apparently given by 

The second law states that Sgenerated 0 hence the real amount of work required must be larger  

This relation holds, of course, for the general exchange of work and heat between a flowing medium and its environment. The abstract formulation of the second law as in 

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