Saturated liquid and vapor

The vessel is assumed to be filled with saturated liquid and vapor. The specific internal energy of the saturated liquid can be computed by substituting the appropriate thermodynamic data of Table 9.3 in Eq. (6.3.23) ... 

The saturated liquid and vapor enthalpies can be expressed as a linear function of compositions. 

Kay, W.B. Vapor pressures and saturated liquid and vapor densities of cyclopentane, methylcyclopentane, ethylcyclopentane and methylcyclohexane, J. Am. Chem. Soc., 69(6) 1273-1277, 1947. 

By interpolation in the table of properties for saturated liquid and vapor, we find for a pressure of 1 bar that... 

Because of the equality of fugacities of saturated liquid and vapor, calculation of fugacity for species i as a compressed liquid is done in two ste First, one calculates the fugacity coefficient of saturated vapor = by integrated form of Eq. (11.20), evaluated for P = P . Then by Eqs. (11. and (11.23),... 

Enthalpies for saturated liquids and vapors are given in Table IV for the pure components referred to zero for the liquids at 32°F. Vapor mixtures are calculated assuming zero heat of mixing. Liquid enthalpies for the mixtures are calculated to include the integral heat of mixing, given according to... 

Thus at a temperature below 0 but differing very slightly from 0 the saturated liquid and vapor are transformed one into the other without appreciable absorption or liberation of heat and without appreciable change of volume the various physical properties, optica, capillary, etc., of one of the two phases cannot be distinguished from the analogous properties of the other phase. 

Enthalpy of vaporization - useful in design of vaporizers and condensers, engineering applications involving saturated liquids and vapors, safety engineering such as ascertaining vaporization quantities from vessel rupture... 

Table 9.1 lists tlie tliemiodynamic properties of saturated liquid and vapor tetrafluo-roetliane. Making use of tlie vapor pressures as a function of temperature and of tlie saturated-liquid and saturated-vapor volumes, calculate tlie latent heat of vaporization by Eq. (4.11) atone of tlie followingtemperaturesand compare tlie result witli tlie value calculated from tlie enthalpy values given in tlie table. 

The properties of a mixture of vapor and liquid in equilibrium (for a single component) can be computed from the individual properties of the saturated vapor and saturated liquid. At 400 K and 245.6 kPa with a specific volume of a wet steam mixture being 0.505 m /kg, what is the quality of the steam From the steam tables the specific volumes of the saturated liquid and vapor are... 

For given T, line MW lies at the vapor pressure Pf if and only if the fugacity coefficients for points M and W satisfy Eq. (4-332). These points then represent saturated liquid and vapor phases in equilibrium at temperature T. 

Assuming we have saturated liquid and vapor in eaeh effeet, the pressure in any effeet is just the vapor pressure at the temperature for that effeet. Reeall that vapor pressure inereases with temperature. 

In the past, engineers used steam tables to obtain properties of water and steam. While such books still exist [6, 7], it is now usually more convenient to use software that implements lAPWS property standards [8]. Table 1.1 reports the thermodynamic properties of water for saturated liquid and vapor. Such short tables are useful for quick reference design calculations usually require more extensive tables or software. 

McMiking, J. H., "Vapor Pressures and Saturated Liquid and Vapor Densities of Isomeric Heptanes and Octanes , Ph. D. Thesis, Ohio State University, Columbus, OH (1961). 

The Ponchon-Savarit method is summarized in Fig. 5.3-8, The methud involves an enlhalpy-coucen-traiion diagram, and tha enthalpies of the saturated liquid and vapor are first plotted on the diagram. Next, the equilibrium lie lines are added, based on phase equilibria. Compositions of feed, distillate, and bottoms are then located on the diagram (in the example shown the feed is mixed vapor-liquid and the distillate and bottoms are saturated liquids). A reflux ratio is cbosen. and the enthalpy of die reflux is located as the lop difference point. A0. (The reflux ratio is equal numerically to the vertical distance from the difference point to the value of yN, divided by the vertical distance from to xD.)... 

The energy u°/k Tc only if rj/k = 0. In other cases it is not related so directly to a macroscopic property but it can be estimated by relying on the accuracy of Equation 12. When all of the characteristic constants are known, Equation 12 yields accurate molar volumes of the saturated liquid and vapor phases obtained by an iteration at constant T and P from the Gibbs equilibrium condition. Hence, if <, V°°, and rj/k have been estimated already, u°/k is found by varying its value until the liquid volume calculated from Equation 12 or from the compressibility factor Z agrees with the observed value at a certain T, say, T/Tc = 0.6. 

---