Water vapor saturation

The temperature at which water condenses from natural gas is called its dew point. If the gas is saturated with water vapor, it is by definition at its dew point. The amount of water vapor saturated in the gas is given... 

If the gas to be compressed contains water vapor (saturated or only partially saturated), this water content must be determined by (1) test of the mixture or (2) calculation. Then the properties of the gas-water vapor mixture must be determined by the usual gas calculations for weighted aver-... 

A classic self-light stroboscopic image of a premixed flame undergoing a tulip inversion in a closed tube. There is an interval of 4.1 ms between the images of a water vapor saturated CO/Oj flame arranged to have a flame speed comparable with that of a stoichiometric methane/air flame. The tube is 2.5 cm in diameter and 20.3 cm long. (Adapted from Ellis, O.C. de C. and Wheeler, R.V., /. Chem. Soc., 2,3215,1928.)... 

Mixing dry and water vapor-saturated air in defined proportions also can be used to generate constant relative humidity. Control of flow rates and the water vapor content of the dry and saturated air are essential [27,28],... 

Figure 2.7 Water vapor saturation level of the air cathode exhaust at a close point of cathode exit of an operating DMFC stack as a function of stack operating temperature and air feed actual stoichiometry.

To demonstrate the feasibility of extrapolating such laboratory results to the field, we use Eq. 20-15 to calculate the order of magnitude of the annual evaporation rates from surface waters. Let us assume a typical relative humidity of 80% (RH = 0.8), wind speeds between 0 and 15 m s"1, and a water temperature of 15°C. Water vapor saturation of air at 15°C is C tera= 12.8 x 10 6 g cm"3 (Appendix B, Table B.3). Thus, from Eq. 20-11 ... 

Basically, perecnl relative humidiiy is an indicator ol the water vapor saturation deficit of ihe gas mixture, rather ihun an indicator of sorption, desorption, comfort, or evaporation. A measurement of RH without a corresponding measurement of dry bulb temperature is not of particular value, since the water vapor content cannot be determined from % RH alone... 

Values for use in Eq. (4.5) for Tin Kelvin, salinity S in per mil, c incm3 STP in 1 kg of solution under 1 atm total pressure of water-vapor-saturated air from Weiss (1970a, 1971a). 

Jacobs et al. (261) have shown that photolysis of water can be achieved using AgY zeolite. Irradiation using sunlight on water vapor-saturated AgY yields oxygen, and thermal treatment (600 C) of the reduced silver zeolite restores the Ag+ cations with the evolution of hydrogen, i.e.,... 

The thennal and hydrothermal stability of a sample with Si/Al = 26 was investigated in our laboratory by heating batches for 3 h in dry air, or in pure water vapor in the temperature range 550 to 850 °C. In dry air, the extent of dealumination increases with the treatment temperature but the crystallinity and the pore structure are preserved. However, under hydrothermal conditions, extensive dealumination takes place even at 550 °C, and the structure collapses above 650 °C. Another investigation of the thermal and hydrothermal stability of ion-exchanged Al-MCM-41 (Si/Al = 39) was carried out by Ryoo et al. [127] using dry or water vapor saturated O2 for 2 h at different temperatures. Under both sets of conditions, the stability was found to depend on the nature of the counter cations in the following order Y Ca > Na = as-prepared Al-MCM-41 > pure silica MCM-41. 

Fig. 9. Current potential characteristics obtained with the cell in Fig. 7 at several temperatures in a water-vapor-saturated oxygen atmosphere [9], (Reprinted by permission of the Electrochemical Society).

Fig. 39 Current-potential characteristics obtained a water vapor-saturated oxygen atmosphere [59].

Ripening. Twelve kg of randomly selected kiwifruit were placed in glass containers in a room kept at 20 C. A stream of water-vapor saturated air containing 5 ppm ethylene gas was passed over the fruit at a rate of 50 ml per minute. The control sample was treated under the same condition except that no ethylene gas was used in the aeration process. Samples of approximately 2 kg each were taken at designated time intervals for physical and chemical tests. 

For tests in moist atmospheres, the hydrogen was passed through gas washers containing distilled water at 15 °C in order to obtain water vapor saturation. 

Moist Adiabatic Lapse Rate Calculation Calculate the moist adiabatic lapse rate at 0°C and 1 atm. An expression for the water vapor saturation vapor pressure as a function of temperature is given in Table 17.2. 

This equation describes the growth/evaporation rate of an atmospheric droplet. The numerator is the driving force for the mass transfer of water, namely, the difference between the ambient saturation SVt00 and the equilibrium saturation for the droplet (or equivalently the water vapor saturation at the droplet surface). The equilibrium saturation includes, as we saw in Section 17.2.4, the contributions of the Kelvin effect (first term in the exponential) and the solute effect (second term in the exponential). When the ambient saturation exceeds the equilibrium saturation, the cloud droplets grow and vice versa. The numerator is qualitatively equivalent to the term cTO 0C - r))1 in (17.60). The first term in the denominator corresponds to the diffusivity of water vapor (compare with (17.60)), while the second accounts for the temperature difference between the droplet and its surroundings. Note that if no heat were released during condensation, AHV = 0, and this term would be zero. 

Figure 25-23. Apparatus with a bundle of three solid-electrolyte tube cells, a gas purification tower, a bottle for water vapor saturation and a flow meter (Th thermocouple, R reference system, 1, 2, 3 terminals of inner electrodes) [80],...

---