When working with two-phase fluids in Flownex, the reported quality value may be less than 0, between 0 and 1, greater than 1, or take special values such as 100 or 1000. What do these quality results represent for subcooled, saturated, superheated, supercritical, gas-only, liquid-gas mixture, and two-phase incondensable mixture conditions?
In Flownex, the quality value (x) is used to indicate the thermodynamic state of a two-phase fluid. A quality of 0 represents a saturated liquid, a quality of 1 represents a saturated vapour, and values between 0 and 1 indicate conditions within the two-phase region. For subcooled fluids, Flownex reports a negative quality value (x < 0) to indicate the extent of subcooling. For superheated fluids, Flownex reports a quality value greater than 1 (x > 1) to indicate the extent of superheating. If the fluid pressure exceeds its critical pressure, the fluid is considered supercritical and Flownex reports a quality of 1000. If the pressure is below the triple-point pressure and the fluid can only exist as a gas, Flownex reports a quality of 100. For liquid-gas mixtures, the reported quality is equal to the gas mass fraction in the mixture. For two-phase incondensable mixtures, the reported quality corresponds to the quality of the two-phase fluid within the mixture.