A small, high-speed turbine operating on compressed air produces a power output of 0.1 hp. The inlet state is 60 lbf/in.2, 120 F, and the exit state is 14.7 lbf/in.2, −20 F. Assuming the velocities to be low and the process to be adiabatic, find the required mass flow rate of air through the turbine.
C.V. Turbine, no heat transfer, no ∆KE, no ∆PE
Energy Eq. hin = hex + wT
Ideal gas so use constant specific heat
wT = hin - hex ≅ Cp(Tin - Tex)
= 0.24(120 - (-20)) = 33.6 Btu/lbm
The dentist’* drill has a small air flow and is not really adiabatic.
