A well-insulated, 0.7-m³ gas cylinder containing natural gas (which can be considered to be pure methane) at 70 bar and 300 K is exhausted until the pressure drops to 3.5 bar. This process occurs fast enough that there is no heat transfer between the cylinder walls and the gas, but not so rapidly as to produce large velocity or temperature gradients in the gas within the cylinder. Compute the number of moles of gas withdrawn and the final temperature of the gas in the cylinder if

a. Methane gas is assumed to be ideal with C^∗_P = 36 J/(mol K). 

b. Methane is considered to be a real gas with the properties given in Fig. 3.3-2.

Fig. 3.3-2.

Transcribed Image Text:

-O THERMODYNAMIC PROPERTIES OF METHANE 100 liquie 200 line 300 400 th 500 0.007 600 (0.01 2014 700 Ĥ, kJ/kg 0.02 m³/kg 5 ku(kg 9.03 800 4007 900 7059 ** 1000 1100 20 10 8 6 4 2 P, MPa 1 0.8 -0.6 9 0.4 0.2 -0.1 1200