Question

An adiabatic vessel contains steam at 1025 psia, 750°F. A valve is opened slowly permitting an outflow of steam; it is closed quickly when the steam remaining in the vessel becomes saturated vapor. What fractional part of the original steam remains? Assume that this part underwent a reversible adiabatic expansion.

Answer 1

$p_1=\frac{\rho RT}M=108~MPa,$

$\eta =\frac p{p_1}=0.065=6.5\%.$