Where is Eq.(28) ?? You should show it to find the result
That is a thread ball valves
It is study of the relationships between heat, temprature, work and energy
Answer:
The entropy change of the air is 
Explanation:

is unknown
we can apply the following expression to find 


now substitute

To find entropy change of the air we can apply the ideal gas relationship
Δ

Δ

Δ
I dont know is your papers main idea stated clearly?