Question

Saturated liquid-vapor mixture of water, called wet steam, in a steam line at 1500 kPa is throttled to 50 kPa and 100°C. What is the quality in the steam line?

Answer 1

`x = 0.944`

Step-by-step explanation:

Steam at outlet is an superheated steam, since
`T > T_(sat)`. From steam tables, the specific enthalpy is:

`h_(out)=2682.4\,(kJ)/(kg)`

The throttle valve is modelled after the First Law of Thermodynamics:

`h_(in) = h_(out)`

Hence, specific enthalpy at inlet is:

`h_(in)=2682.4\,(kJ)/(kg)`

The quality in the steam line is:

`x = (2682.4\,(kJ)/(kg)-844.55\,(kJ)/(kg))/(2791.0\,(kJ)/(kg) - 844.55\,(kJ)/(kg) )`

`x = 0.944`