Answer:
For isentropic process : Q= 0 ,[tex]\Delta W=-mC_v(T_2-T_1)[/tex]
For constant volume : [tex]\Delta Q=mC_v(T_3-T_2)[/tex],W=0
Explanation:
Given that:
System is closed
In first process ideal gas goes an isentropic expansion and then constant volume heat rejection.
We know that from first law of thermodynamic
Q = ΔU +  W
For process 1-2:
Process is adiabatic it means that Q=0
So  Q = ΔU +  W
0 =  ΔU +  W
W= -ΔU
We know that internal energy for ideal gas
[tex]\Delta U=mC_v(T_2-T_1)[/tex]
So work W
[tex]\Delta W=-mC_v(T_2-T_1)[/tex]
For process 2-3:
Process is constant volume so work transfer will be zero ,W=0
Q = ΔU +  W
Q = ΔU +  0
Q = ΔU
[tex]\Delta U=mC_v(T_3-T_2)[/tex]
[tex]\Delta Q=mC_v(T_3-T_2)[/tex]