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• Notes
• entropy canbe created but it cannot be destroyed
• the entropy change of asystem during a process is greater than the entropy transfer by an amount equal to the entropy generated during the process within the system

$S_{\mathrm{in}}-S_{\mathrm{out}}+S_{\mathrm{gen}}=\Delta S_{\mathrm{system}}$

• the entropychange of a system during a process is equal to the net entropy transfer through the system boundary and the entropy generated within the system.
• Entropy balance for closed system: The entropy change of a closed system during a process is equal to the sumof the net entropy transferred through the system boundary by heat transfer and the entropy generated within the system boundaries

$\sum \frac{Q_{k}}{T_{k}}+S_{\mathrm{gen}}=\Delta S_{\mathrm{system}}=S_{2}-S_{1} \quad(\mathrm{kJ} / \mathrm{K})$

• Entropy balance for control volume: The rate of entropy change within the control volume during a process isequal to the sum of the rate of entropy transfer through the control volume boundary by heat transfer, the net rate of entropy transfer into the control volume by mass flow, and the rate of entropy generation within the boundaries of the control volume as a result of irreversibilities.

$\sum \frac{Q_{k}}{T_{k}}+\sum m_{i} s_{i}-\sum m_{e} s_{e}+S_{\mathrm{gen}}=\left(S_{2}-S_{1}\right)_{\mathrm{Cv}}$