6.163   As shown in Fig. P6.163, air enters the diffuser of a jet engine at 18 kPa, 216 K with a velocity of 265 m/s, all data corresponding to high-altitude flight.The air flows adiabatically through the diffuser, decelerating to a velocity of 50 m/s at the diffuser exit. Assume steady-state operation, the ideal gas model for air, and negligible potential energy effects.

(a)     Determine the temperature of the air at the exit of the diffuser, in K.

(b)    If the air would undergo an isentropic process as it flows through the diffuser, determine the pressure of the air at the diffuser exit, in kPa.

(c)     If friction were present, would the pressure of the air at the diffuser exit be greater than, less than, or equal to the value found in part (b)? Explain.

 

undergoes a throttling process to a pressure of 2 bar. Determine the rate of entropy production per unit mass of ammonia flowing, in kJ/kg ? K. If the valve were   replaced

by a power-recovery turbine operating at steady state, determine the maximum theoretical power that could be developed per unit mass of ammonia flowing, in kJ/kg, and comment. In each case, ignore heat transfer with the surroundings and changes in kinetic and potential  energy.