MECH 237 Chapter Notes - Chapter 7: Mass Flow Rate, Ween, Flow Device
28 Apr 2017
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Isothermal heat transfer processes are internally reversible, thus the entropy change during this process is: Losing heat is the only way the entropy of a system can be decreased. 7. 2: the increase of entropy principle: consider a cycle made up of two processes: process 1-2 (which can be reversible or irreversible) and process 2-1 which is internally reversible. This means: ds : we may conclude that the entropy change of a closed system during an irreversible process is greater than the entropy transfer (q/t evaluated) for that process. + sgen: entropy generation is always a positive quantity or zero. Its value depends on the process but it is not a property of the system. In the absence of any entropy transfer, the entropy change of a system is equal to the entropy generation. For an isolated system (or an adiabatic closed system), the heat transfer is zero and thus:
