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• Notes
• Exergy can be transferred to or from a system in three forms:heat, work, and mass flow
• Exergy transfer by heat:

$\quad X_{\text { heat }}=\left(1-\frac{T_{0}}{T}\right) Q \quad(\mathrm{kJ})$

When the temperature T is constant

$X_{\mathrm{heat}}=\int\left(1-\frac{T_{0}}{T}\right) \delta Q$

When the temperature T is not constant

• Exergy Transfer by Work:

$X_{\text { work }}=\left\{\begin{array}{ll}{W-W_{\text { surr }}} & {\text { (for boundary work) }} \\ {W} & {\text { (for other forms of work) }}\end{array}\right.$

where $W_{\text { surr }}=P_{0}\left(V_{2}-V_{1}\right), P_{0}$ is atmospheric pressure, and $V_{1}$ and $V_{2}$ are theinitial and final volumes of the system.

• Exergy transfer by mass:

$\quad X_{\text { mass }}=m \psi$

where $\psi=\left(h-h_{0}\right)-T_{0}\left(s-s_{0}\right)+V^{2} / 2+g z$