Steam quality

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Steam quality is the proportion of saturated steam in a saturated water/steam mixture. A steam quality of 0 indicates 100% water while a steam quality of 1 indicates 100% steam. Steam quality is very useful in determining enthalpy of saturated water/steam mixtures since the enthalpy of steam (gaseous state) is many orders of magnitude higher than enthalpy of water (liquid state).

Mathematically, quality is defined by the relationship x = massofvapor / totalmass. This can be translated to x = (yy[f]) / y[fg], where y is equal to either specific enthalpy, specific entropy, specific volume or specific internal energy. y[f] is the value of the specific property of the substance in the liquid state while under saturated conditions, and y[fg] is the value of the specific property of the substance in the gas state minus that of the liquid state.