6.169 A tank initially containing air at 30 atm and 5408F is connected to a small turbine. Air discharges from the tank through the turbine, which produces work in the amount of 100 Btu. The pressure in the tank falls to 3 atm during the process and the turbine exhausts to the atmosphere at 1 atm. Employing the ideal gas model for the air and ignoring irreversibilities within the tank and the turbine, determine the volume of the tank, in ft3. Heat transfer with the atmosphere and changes in kinetic and potential energy are negligible.
6.170 Air enters a 3600-kW turbine operating at steady state with a mass flow rate of 18 kg/s at 8008C, 3 bar and a velocity of 100 m/s. The air expands adiabatically through the turbine and exits at a velocity of 150 m/s. The air then enters a diffuser where it is decelerated isentropically to a velocity of 10 m/s and a pressure of 1 bar. Employing the ideal gas model, determine
(a) the pressure and temperature of the air at the turbine exit, in bar and 8C, respectively.
(b) the rate of entropy production in the turbine, in kW/K. Show the processes on a T-s diagram.