Water vapor enters a turbine at $25$ bars and $420\backslash$deg C$,$ and is expanded to $1\mathrm{.}5$ bar and $170\backslash$deg C in an adiabatic steady$-$flow process. The ambient conditions are $1$ bar and $27\backslash$deg C$.$ Neglect the changes in kinetic and potential energy and determine. The work rev. Or to the exergy of the system.