For a reversible process a process that involves no

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Unformatted text preview: ion always cause the entropy of a system to increase, and entropy generation is a measure of the entropy created by such effects during a process. For a reversible process (a process that involves no irreversibilities), the entropy generation is zero and thus the entropy change of a system is equal to the entropy transfer. Therefore, the entropy balance relation in the reversible case becomes analogous to the energy balance relation, which states that energy change of a system during a process is equal to the energy transfer during that process. However, note that the energy change of a system equals the energy transfer for any process, but the entropy change of a system equals the entropy transfer only for a reversible process. The entropy transfer by heat Q/T is zero for adiabatic systems, and the entropy transfer by mass ms is zero for systems that involve no mass flow across their boundary (i.e., closed systems). Entropy balance for any system undergoing any process can be expressed more explicitly as Sin Mass Sout Sgen ∆Ssystem System 14243 13 2 123 Mass Net entropy transfer by heat and mass Entropy generation Sgen ≥, 0 (kJ/K) (7–76) Change in entropy ∆ Ssystem Heat...
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This document was uploaded on 11/28/2012.

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