Page 46 - BASIC CONCEPTUAL OF THERMOFLUID

EXAMPLE 4

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3
3.4 kg of gas is heated at a constant volume of 0.92 m and temperature 17 C until the
o
temperaturerose to 147 C. If the gas is assumed to be a perfect gas, determine:
a) the heat flow during the process
b) the beginning pressure of gas

c) the final pressure of gas

Given
Cv = 0.72 kJ/kg K

R = 0.287 kJ/kg K

SOLUTION : EXAMPLE 4

m = 3.4 kg
V 1 = V 2 = 0.92 m 3
T1 =17 + 273 = 290 K T1 =147 + 273 = 420 K

C V = 0.72 kJ/kgK R = 0.287 kJ/kgK

a. Heat flow b. initial pressure ga
Q 12 = mC v (T 2 - T 1 ) P 1 V 1 = mRT 1

Q 12 = (3.4)(0.72)(420 - 290) P = mRT
1

Q 12 = 318 kJ

c. Final pressure gas
P 2 V 2 = mRT 2
P = mRT 2
2
V
P

Specific Heat Capacity at Constant PRESSURE (Cp)

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