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• Notes
• Exergy (Work Potential of Energy) is the maximum useful work possible during a process that brings the system into equilibrium with a heat reservoir, reaching maximum entropy.
• Thedead state : the state when a system is in thermodynamicequilibrium with the environment
• Surroundings are everything outside the system boundaries.
• The immediate surroundings: the portion of the surroundings that is affected by the process.
• Environment: the region beyond the immediate surroundings whoseproperties are not affected by the process at any point
• Exergy: the useful work potential of the system at the specified state
• Exergy of kinetic energy: the kinetic energy itself regardless of the temperature and pressure of the environment

$x_{\mathrm{ke}}=\mathrm{ke}=\frac{V^{2}}{2} \quad(\mathrm{kJ} / \mathrm{kg})$

• Exergy of the potential energy: the potential energy itself regardless of the temperatureand pressure of the environment

$x_{\mathrm{pe}}=\mathrm{pe}=g z$

• The surroundings work: the work done by or against thesurroundings during a process

$W_{\operatorname{surr}}=P_{0}\left(V_{2}-V_{1}\right)$

• The useful work: The difference between the actual work and the surroundings work

$W_{u}=W-W_{\mathrm{surr}}=W-P_{0}\left(V_{2}-\mathrm{V}_{1}\right)$

• Reversible work: the maximum amount of useful workthat can be produced as a system undergoes a process between the specified initial and final states
• irreversibility I : difference between the reversible work and the useful work

$I=W_{\mathrm{rev}, \mathrm{out}}-W_{u, \mathrm{out}}$ or $I=W_{u, \mathrm{in}}-W_{\mathrm{rev} ; \mathrm{in}}$