Applying the Exergy Balance: Control VolumesFigure P7.89 shows a gas turbine power plant o...

Applying the Exergy Balance: Control Volumes

Figure P7.89 shows a gas turbine power plant operating at steady state consisting of a compressor, a heat exchanger, and a turbine. Air enters the compressor with a mass flow rate of 3.9 kg/s at 0.95 bar, 22°C and exits the turbine at 0.95 bar, 421°C. Heat transfer to the air as it flows through the heat exchanger occurs at an average temperature of 488°C. The compressor and turbine operate adiabatically. Using the ideal gas model for the air, and neglecting the effects of motion and gravity, determine, in MW,

(a) the rate of exergy transfer accompanying heat transfer to the air flowing through the heat exchanger.

(b) the net rate exergy is carried out of the plant at the turbine exit, (Ėf2 − Ėf1).

(c) the rate of exergy destruction within the power plant.

(d) Using the results of parts (a)–(c), perform a full exergy accounting of the exergy supplied to the power plant accompanying heat transfer. Comment.

Let T0 = 295 K(22°C), p0 = 0.95 bar.

Fig. P7.89