Question

0.5 kg of an ideal gas undergoes an isentropic process from 657 kPa gage and a volume of 0.017 cubic meter to a final volume of 0.1 cubic meter. If Cv = 0.384 kJ/kg-K and Cp = 0.52 kJ/kg-K, calculate:

a) the final temperature in deg. C

b) the final pressure in kPa

c) the change in enthalpy in kJ

d) the work nonflow in kJ

Answer 1

a)

$\nu=\frac{C_p-C_V}R=16.4~mol,$

$\gamma=1+\frac{\nu R}{C_V}=1.36,$

$T_1=\frac{p_1V_1}{\nu R}=82~K,$

$T_2=T_1(\frac{V_1}{V_2})^{\gamma-1}=43~K=-230°C,$

b)

$p_2=\frac{\nu RT_2}{V_2}=58.6~kPa,$

c)

$\Delta H=mC_p\Delta T=10.2~kJ,$

d)

$A=\nu C_V\Delta T=246~kPa.$