A large pressure vessel contains air in state 1 (p1 = 3 bar, T = 360...

 

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A large pressure vessel contains air in state 1 (p1 = 3 bar, T₁ = 360 K, c₁ = 0 m/s). The air flows stationary through an adiabatic laval nozzle (n-D=0.9) connected to a tank and leaves the nozzle (state 2: p2 = 1 bar, cross-sectional area 42 = 0.1 m²) at supersonic velocity. The air (molar mass M = 28.96 g/mol) can be considered an ideal gas with a constant isentropic exponent x = 1.4. a) Determine the air mass flow through the nozzle. b) Determine the minimum temperature to which the air in the container must be heated up if the temperature of the air at the nozzle outlet has to be kept higher than 72 = 290 K. The pressures p1 = 3 bar and p2 = 1 bar remain unchanged. c) Determine the entropy change for the cases a) and b) and give a short explanation for the result. A large pressure vessel contains air in state 1 (p1 = 3 bar, T₁ = 360 K, c₁ = 0 m/s). The air flows stationary through an adiabatic laval nozzle (n-D=0.9) connected to a tank and leaves the nozzle (state 2: p2 = 1 bar, cross-sectional area 42 = 0.1 m²) at supersonic velocity. The air (molar mass M = 28.96 g/mol) can be considered an ideal gas with a constant isentropic exponent x = 1.4. a) Determine the air mass flow through the nozzle. b) Determine the minimum temperature to which the air in the container must be heated up if the temperature of the air at the nozzle outlet has to be kept higher than 72 = 290 K. The pressures p1 = 3 bar and p2 = 1 bar remain unchanged. c) Determine the entropy change for the cases a) and b) and give a short explanation for the result.