PROBLEM $3$:

A power cycle consisting of the three processes:

Process $1-2$: Constant volume to $P_2$

Process $2-3$: Polytropic expansion $P{v}^k=c,$ use $k=1\mathrm{.}28$

Process $3-1$: Compression at constant pressure

Assuming $2\mathrm{.}5$ kg carbon dioxide as the working substance with $P_1=\frac{1\mathrm{.}5}{b}ar,$

$P_2=6$ bar, $T_1=350K$ and neglecting kinetic and potential energy effects:

a$)$ sketch cycle in P$-$v diagram

b$)$ calculate thermal efficiency

$C{O}_2$ molar mass $=44.$

$C{O}_2$ specific heat $c_v=1\mathrm{.}014k\frac{J}{k}\frac{g}{K}$