Page 45 - BASIC CONCEPTUAL OF THERMOFLUID

EXERCISE 2

3
0.04 kg of a certain perfect gas occupies a volume of 0.0072 m at a pressure 6.76 bar and a
o
temperature of 127 C. Calculate the molecular weight of the gas (M). When the gas is allowed to
3
expand until the pressure is 2.12 bar the final volume is 0.065 m . Calculate the final temperature.
SOLUTION : EXERCISE 2

m = 0.04 kg

V1 = 0.072 m 3 V2 = 0.065 m 3

P = 6.76 bar = 676 kN/m 2 P = 2.12 bar = 21
1
2
T1 =127 + 273 = 400 K

Gas constant

P V = mRT 1
1 1

P V 676´ 0
R = 1 1 =
RT

1
R = 0.3

Specific Heat Capacity at Constant Volume (Cv)

FIGURE 3.4 p - v diagram for
reversible constant volume process

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