PROPERTY DIAGRAMS AND STEAM TABLES Thermodynamicsnfg= specific volume change of vaporization (ft3/lbm)h = specific enthalpy (Btu/lbm)hf= specific enthalpy of saturated liquid (Btu/lbm)hg= specific enthalpy of saturated vapor (Btu/lbm)hfg= specific enthalpy change of vaporization (Btu/lbm)s = specific entropy (Btu/lbm-°R)sf= specific entropy of saturated liquid (Btu/lbm-°R)sg= specific entropy of saturated vapor (Btu/lbm-°R)sfg= specific entropy change of vaporization (Btu/lbm-°R)Sh = number of degrees of superheat (°F)The saturated steam tables give the energy transfer properties of saturated water and saturatedsteam for temperatures from 32 to 705.47°F (the critical temperature) and for the correspondingpressure from 0.08849 to 3208.2 psi. Normally, the saturated steam tables are divided into twoparts: temperature tables, which list the properties according to saturation temperature (Tsat); andpressure tables, which list them according to saturation pressure (Psat). Figure A-2 shows aportion of a typical saturated steam temperature table and a portion of a typical saturated steampressure table. The values of enthalpy and entropy given in these tables are measured relativeto the properties of saturated liquid at 32°F. Hence, the enthalpy (hf) of saturated liquid and theentropy (sf) of saturated liquid have values of approximately zero at 32°F.Most practical applications using the saturated steam tables involve steam-water mixtures. Thekey property of such mixtures is steam quality (x), defined as the mass of steam present per unitmass of steam-water mixture, or steam moisture content (y), defined as the mass of water presentper unit mass of steam-water mixture. The following relationships exist between the quality ofa liquid-vapor mixture and the specific volumes, enthalpies, or entropies of both phases and ofthe mixture itself. These relationships are used with the saturated steam tables.HT-01 Page 48 Rev. 0
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