solution

Air enters an insulated nozzle operating at steady state at 80 lbf/in.2 , 120 F, 10 ft/s with a mass flow rate of 0.4 lb/s. At the exit, the velocity is 914 ft/s and the pressure is 50 lbf/in.2 Determine

(a) the isentropic nozzle efficiency.

(b) the exit area, in ft2 .

Refrigerant 134a enters a compressor operating at steady state as saturated vapor at 4 C and exits at a pressure of 8 bar. There is no significant heat transfer with the surroundings, and kinetic and potential energy effects can be ignored.

(a) Determine the minimum theoretical work input required, in kJ per kg of refrigerant flowing through the compressor, and the corresponding exit temperature, in C.

(b) If the refrigerant exits at a temperature of 40 C, determine the isentropic compressor efficiency.