Chapter 2
Q. 2.17
An air cycle is completed by two processes as follows :
(i) Compression process : 240 kJ of work is done on air while 100 kJ of heat is rejected to the surroundings.
(ii) Expansion process : air does 320 kJ of work. Calculate the quantity of heat added to the cycle.
Step-by-Step
Verified Solution
The cycle is shown in Fig. 2.30.
Compression process 1 – 2 :
From first law of thermodynamics, we have
\begin{aligned}U_2-U_1 &=Q_{1-2}-W_{1-2} \\&=-100-(-240)=140 \ kJ\end{aligned}
Expansion process 2 – 1 :
\begin{aligned}Q_{1-2} &=\left(U_1-U_2\right)+W_{1-2} \\&=-140+320=180 \ kJ\end{aligned}
