Thermal question. please help!! Consider a rigid tank whose internal volume is 1

Question

Thermal question. please help!!

Consider a rigid tank whose internal volume is 1 m^3. The tank initially contains air at a temperature of 300 K and a pressure of 4 bar and the local surroundings are also at 300 K but a pressure of 1 bar. The tank is connected to a pressure regulator valve, a throttling device that controls the outflow from the tank. The pressure regulator valve is opened and air flows out of the tank Into the large surroundings until the pressure in the tank drops to 1 bar. Heat transfer maintains the air Pressure inside the tank at 300 K.

Explanation / Answer

P1= 4bar = 4 *105 N/m2                            T1 = T2 = 300 K

P2 = 1 bar = 1*105 N/m2        

R=287 J/kg K

V = 1 m3  

Mass of the air before opening

PV= mRT

A)

m1 = (P1V)/(RT1) = 6.968 kg ( Initial mass)

m2 = ( P2V) / (RT2) = 1.16144 kg ( Final MAss)

B)

Heat transfer to maintain the temperature

Q=P1V1 ln( P2/P1)

   = 554517.74 W

C)

Amount of entropy
At contant Volume

Del S= m Cv ln(T2 / T1 )

Since T2 = T1

Enropy is Zero

D)

    

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