Air flows steadily in an adiabatic duct where no shaft work

Air flows steadily in an adiabatic duct where no shaft work is involved. At one section, the total pressure is 50 psia, and at another section, it is 67.3 psia. In which direction is the fluid flowing, and what is the entropy change between these two sections?

Solution

The liquid is flowing from 67.3 to 50

Since it is adiabatic flow then entropy change is zero