Question

A reversible cycle receives $40$ kJ of heat from one heat source at a temperature of ${127}^{o}C$ and $37$ kJ from another heat source at ${97}^{o}C$. The heat rejected (in kJ) to the heat sink at ${47}^{o}C$ is

• A. 64

Answer 1

The correct option is A 64

Given data:
$T_1={127}^{o}C=(127+273)K=400K$
$T_2={97}^{o}C=(97+273)K=370K$
$T_3={47}^{o}C=(47+273)K=320K$
For reversible cycle
Clausius inequality, $\oint \frac{\delta Q}{T}=0$
$\therefore \frac{4Q}{400}+\frac{37}{370}-\frac{Q_3}{320}=0$
$0.1+0.1=\frac{Q_3}{320}$
or $Q_3=64$ kJ