Question

A polytropic process of air from 1034 kPa, 149 deg. C and 0.028 m3 occurs to 138 kPa in accordance with pV1.3 = C. Determine:

(a) the final temperature in deg. C

(b) the change in internal energy in kJ

(c) the work nonflow in kJ

(d) the heat in kJ from the formula using polytropic specific heat

Answer 1

a)

$T_2=T_1(\frac{p_2}{p_1})^{1-\frac 1{\gamma}}=265~K=-8°C,$

b)

$A=\frac{p_1V_1}{\gamma-1}(1-(\frac{p_2}{p_1})^{1-\frac 1{\gamma}})=35.8~kPa.$