Reduced Specific Volume

Reduced specific volume, abbreviated as \(\upsilon_r \) (Greek symbol upsilon), of a fluid is ratio of the specific volume of a substance's critical pressure and temperature.  The specific volume of a substance is defined as the volume per unit mass of that substance. 

The term "reduced specific volume" typically refers to the specific volume of a substance normalized or reduced with respect to some reference conditions, often the critical point.  The critical point is a set of specific temperature and pressure conditions beyond which a substance cannot exist as distinct liquid and gas phases.

This quantity is useful in thermodynamics and fluid mechanics because it allows for the comparison of substances under different conditions.  By using reduced properties, scientists and engineers can express equations of state and other thermodynamic relationships in a more general form that applies to a wide range of substances.

 

Reduced Specific Volume formula
\( \upsilon_r = \upsilon \; p_c \;/\; R \; T_c \)
Symbol	English	Metric
\( \upsilon_r \)  (Greek symbol upsilon) = reduced specific volume	\(ft^3 \;/\; lbm\)	\(m^3 \;/\; kg\)
\( p_c \) = critical pressure	\(lbf \;/\; in^2\)	\( Pa\)
\( T_c \) = critical temperature	\( F \)	\( K \)
\( \upsilon\)  (Greek symbol upsilon) = specific volume	\(ft^3 \;/\; lbm\)	\(m^3 \;/\; kg\)
\( R \) = universal gas constant	\(lbf-ft \;/\; lbmol-R \)	\(J \;/\; kmol-K \)