Quality (or Vapor Quality) and Two-Phase Mixture Properties
\(\displaystyle x = \frac{m_{g}}{m_{f} + m_{g}}\)
\(\displaystyle v = (1-x)v_f + xv_g = v_f + x(v_g - v_f)\)
\(\displaystyle u = (1-x)u_f + xu_g = u_f + x(u_g - u_f)\)
\(\displaystyle h = (1-x)h_f + xh_g = h_f + x(h_g - h_f)\)
\(\displaystyle s = (1-x)s_f + xs_g = s_f + x(s_g - s_f)\)
Symbols
  • \(x\) — quality (or vapor quality)
  • \(m\) — mass
  • \(v\) — specific volume
  • \(u\) — specific internal energy
  • \(h\) — specific enthalpy
  • \(s\) — specific entropy
  • subscript \(f\) — saturated liquid state
  • subscript \(g\) — saturated vapor state

Schematic

Liquid-vapor two-phase region schematic

Inputs & Outputs

The fluid is water.

Saturation pressure \(p_{\text{sat}}\)
bar
Sat. liquid \(v_f\)
m³/kg
Sat. vapor \(v_g\)
m³/kg
Specific volume \(v\)
m³/kg
Sat. liquid \(u_f\)
kJ/kg
Sat. vapor \(u_g\)
kJ/kg
Specific int. energy \(u\)
kJ/kg
Sat. liquid \(h_f\)
kJ/kg
Sat. vapor \(h_g\)
kJ/kg
Specific enthalpy \(h\)
kJ/kg
Sat. liquid \(s_f\)
kJ/(kg·K)
Sat. vapor \(s_g\)
kJ/(kg·K)
Specific entropy \(s\)
kJ/(kg·K)

Plots

All properties used in this simulation come from the CoolProp database. The red dot marks the state point for the current temperature and quality. Use the inputs above to move it, or drag it directly on any of the plots.