$11-89$

Consider a combined gas$-$steam power cycle. The

topping cycle is a simple Brayton cycle that has a

pressure ratio of $7.$ Air enters the compressor at $15^($@$)$C at a rate of

$40$kg$//$s and the gas turbine at $950^($@$)$C$.$ The bottoming cycle is a

reheat Rankine cycle between the pressure limits of $6$ MPa and

$10$ kPa $.$ Steam is heated in a heat exchanger at a rate of $4\mathrm{.}6$kg$//$s

Please show all work, interpolations and tables used

by the exhaust gases leaving the gas turbine, and the exhaust

gases leave the heat exchanger at $200^($@$)$C$.$ Steam leaves the high$-$

pressure turbine at $1\mathrm{.}0$ MPa and is reheated to $400^($@$)$C in the heat

exchanger before it expands in the low$-$pressure turbine. Assum$-$

ing $80$ percent isentropic efficiency for all pumps and turbines,

determine $($a$)$ the moisture content at the exit of the low$-$pressure

turbine, $($b$)$ the steam temperature at the inlet of the high$-$

pressure turbine, $($c$)$ the net power output and the thermal effi$-$

ciency of the combined plant. This problem is solved using

appropriate software.

FIGURE P$11-89$