Vapor Pressure and Other Saturation Properties of Water

VAPOR PRESSURE AND OTHER SATURATION PROPERTIES OF WATER... 

Vapor Pressure and Other Saturation Properties of Water... 

VAPOR PRESSURE AND OTHER SATURATION PROPERTIES OF WATER AT TEMPERATURES UP TO 100 C (373.15 K) ... 

Natural waters formed of —99.7% of H2 0 are also constituted of other stable isotopic molecules, mainly H2 0 (—2%o), H2 0 ( 0.5%o), and HD 0 (—0.3%c), where H and D (deuterium) correspond to and H, respectively. Owing to slight differences in physical properties of these molecules, essentially their saturation vapor pressure, and their molecular diffusivity in air, fractionation processes occur at each phase change of the water except sublimation and melting of compact ice. As a result, the distribution of these water isotopes varies both spatially and temporally in the atmosphere, in the... 

The values for vapor pressure, from 0 to 32 F, were calculated from data In the International Critical Tables/ All other values were taken from Harr, Gallagher, and Kell, NBS/NRC Steam Tables, National Standard Reference Data System, 1984, p. 9. Data on specific volumes of saturated water vapor from 0 to 32 F were obtained from Goff, J. A., and Gratch, S-, "Low-Pressure Properties of Water from -160 to 212°F," Heating, Piping, and Mr Conditioning, Vol 18, No. 2, Feb. 1946, pp. 125-136. 

Property values for superheated water vapor and subcooled liquid water are presented in Appendices B.4 and B.5, respectively. In these regions, T and P are independent, so if we specify both, we constrain the state of the system. The tables are organized first according to pressure, then by temperature at each specified pressure. With T and P specified, values of the other properties (o, m, h, and s) are reported. The data in the superheated steam tables begin with the saturated state, whereas the data in the subcooled water tables end at saturation. The usefulness of the steam tables is that in knowing any two independent properties of water, we may look up the values of any of the other properties to solve engineering problems. 

Sorption equilibria and kinetics are influenced by the nature of the adsorbent and the adsorbate, by the mechanism of adsorption, and by environmental parameters such as temperature, relative humidity, concentration of the adsorbate, and air velocity and turbulence past the adsorbent surface. Air velocity and turbulence only affect sorption kinetics the other parameters also affect equilibria. In general, low adsorbate saturation vapor pressure, low temperature, and high adsorbate concentration in the air increase adsorption. Relative humidity does not always affect adsorption. Colombo et al. (1993) found a 35 % decrease in adsorbed mass when relative humidity was changed from <10 % to 35 %, but only an 8 % decrease when the humidity was increased from 35 % to 70 %. Building materials, which are exposed to indoor air in the normal humidity range of 35-70 %, will typically already be covered by at least one monolayer of adsorbed water, and the formation of multilayers will only have a limited influence on sorption properties for other airborne substances. Kirchner et al. (1997) found that an increase in air velocity increased the rate of desorption of a VOC mixture from painted gypsum, but not from carpet. The air velocity of air above the tuft may be insignificant for the desorption processes of carpet fibers deeper in the tuft. 

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