Of moist air

The density of moist air depends upon the temperature, the humidity, and the barometric pressure. It is expressed by the equation... 

The refractive index of moist air can be calculated from the expression... 

Thermodynamic principles govern all air conditioning processes (see Heat exchange technology, heat transfer). Of particular importance are specific thermodynamic appHcations both to equipment performance which influences the energy consumption of a system and to the properties of moist air which determine air conditioning capacity. The concentration of moist air defines a system s load. 

Psychrometrics. Psychrometrics is the branch of thermodynamics that deals specifically with moist air, a biaary mixture of dry air and water vapor. The properties of moist air are frequentiy presented on psychrometric charts such as that shown ia Figure 2 for the normal air conditioning range at atmospheric pressure. Similar charts exist for temperatures below 0°C and above 50°C as well as for other barometric pressures. AH mass properties ate related to the mass of the dry air. 

In the presence of moist air, MnCl2 vapor decomposes into hydrochloric acid and manganese oxides. 

Sulfur combines direcdy and usually energetically with almost all of the elements. Exceptions include gold, platinum, iridium, and the hehum-group gases (19). In the presence of oxygen or dry air, sulfur is very slowly oxidized to sulfur dioxide. When burned in air, it forms predominantly sulfur dioxide with small amounts of sulfur trioxide. When burned in the presence of moist air, sulfurous acid and sulfuric acids are slowly generated. 

Experimentally it has been shown that for air-water systems the value of Tj /Zc c, the psychrometric ratio, is approximately equal to 1. Under these conditions the wet-bulb temperatures and adiabatic-saturation temperatures are substantially equal and can be used interchangeably. The difference between adiabatic-saturation temperature and wet-bulb temperature increases with increasing humidity, but this effect is unimportant for most engineering calculations. An empirical formula for wet-bulb temperature determination of moist air at atmospheric pressure is presented by Liley [Jnt. J. of Mechanical Engineering Education, vol. 21, No. 2 (1993)]. 

Example 2 Determination of Moist Air Properties Find the properties of moist air when the dry-bulb temperature is 80 F and the wet-bulb temperature is 67 F. 

TABLE 12-1 Thermodynamic Properties of Moist Air (Standard Atmospheric Pressure, 29 921 inHg)... 

AH = moisture-content correction of air saturated at wet-bulb temperature when barometric pressure differs from standard barometer, gr/lb dry air NOTE To obtain AH reduce value of AH by 1 percent where t — t, = 24 F and correct proportionally when t — is not 24 F h = enthalpy of moist air, Btu/lb dry air... 

FIG. 12-6 Diagram of psychrometric chart showing the properties of moist air. 

The specific volume of moist air in cubic feet per pound of dry air can be determined for other pressures, if ideal-gas behavior is assumed, by the following equation ... 

Computerized psychometric chart. User provides two independent properties of moist air and program calculates the remaining properties. 

Witlox, H. W. M., 1993, Thermodynamics Model for Mixing of Moist Air with Pollutant Consisting of HF, Ideal Gas, and Water, Shell Research Limited, Thornton Research Center, TNER.93.021,. 

ASHRAE Standard 41.6-1994. Measurement of Moist Air Properties. American Society of Heating, Refrigerating, and Air-conditioning Engineers, Atlanta, 1994. 

Percentage saturation The ratio of tJie moisture content of moist air at a given temperature to the moisture content of saturated air at the same temperature. Also known as degree of saturation. 

Specific humidity The mass of water vapor that is present in a unit mass of moist air. 

The study of moist air. The psychrometric chart shows the relationship between the various properties of moist air in graphical form and can be used for the solution of problems. 

Dining interaction at ambient temperature in a bomb to produce poly (carbon monofluoride), admission of fluorine beyond a pressure of 13.6 bar must be extremely slow and carefully controlled to avoid a violently exothermic explosion [1], Previously it had been shown that explosive interaction of carbon and fluorine was due to the formation and decomposition of the graphite intercalation compound, poly (carbon monofluoride) [2], Presence of mercury compounds prevents explosion during interaction of charcoal and fluorine [3], Reaction of surplus fluorine with graphite or carbon pellets was formerly used as a disposal method, but is no longer recommended. Violent reactions observed when an exhausted trap was opened usually involved external impact on the metal trap, prodding the trap contents to empty the trap, or possibly ingress of moist air... 

Mixtures of liquid fluorine and ice are highly impact-sensitive, with a power comparable to that of TNT. Contact of moist air or water with liquid fluorine can thus be very hazardous [1,2]. 

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