Triatomic gases

Triatomic Gases.—Kell et al measured mass, p, and T of water vapour in a nearly constant volume for various temperatures between 150 and 450 C, and pressures in the range 0.6 to 94 bar. They calculated B, C, and A and expressed B and C as functions of T. The same workers carried out a similar study of deuterium oxide vapour, the range of variables being 150 to 500 °C and 1.0 to 101 bar. They calculated B and C, and showed that B for D2O is very slightly more negative than B for HgO. 

Lewis and Fredericks measured mass, p, and T of hydrogen sulphide in a fixed volume for various temperatures between 100 and 220 C (the supercritical region), and pressures in the range 90 to 1700 bar. They calculated B, C, D, E, and F. Clarke and Glew correlated published data (but not ref. 66) on hydrogen sulphide in terms of the Redlich-Kwong equation, and predicted the constants for deuterium sulphide. 

Hajjar et al. studied the low-pressure compressibility of carbon disulphide at various temperatures between 40 and 200 Their calculated values of B vary more rapidly with temperature than do values selected from earlier work.  

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N2, etc., at low temperatures. That of the halogens is greater, and Boltzmann supposed the connexion between the atoms was loosened with rise of temperature. Triatomic gases have the 6R... 

Radiation from clear gas does not follow the Stefan-Boltzmann fourth-power law. The only clear gases that emit or absorb radiation appreciably are those having three or more atoms per molecule (triatomic gases) such as CO2, H2O, and SO2. An exception is diatomic carbon monoxide (CO), which gives off less radiation. The other diatomic gases, such as O2, N2 (and their mixture, air), and H2 have only negligible radiating power. 

Radiation heat transfer, as used in the simplified time lag method for creating furnace heating curves (temperature vs. time) is really an average condition of the gas blanket temperature, gas blanket thickness, and vapor pressure of triatomic gases. With high excess air, the heat transfer will be less due to lower percentages of the... 

Increase the percentage of triatomic gases in the products of combustion— by using less excess air or by enriching the combustion air with oxygen... 

A3. Triatomic gases, of which CO2 and H2O are the most common in furnace... 

Heat transfer in low-temperature rotary drums is largely by convection because radiation is naturally less intense in this temperature range. If the drum diameter is 5 ft (1.5 m) or more, radiation from triatomic gases can be helpful. However, many low-temperature rotary dryers use so much excess air (for moisture pickup) that the triatomic gas concentration is diluted signiflcantly. 

Fig. 5.5. Solids and flames radiant energy long-dashedarrows) and convective energy curved arrows) are absorbed by refractories, raising their temperature then the walls re-radiate to the loads. Triatomic gases in the flame and everywhere in the furnace radiate everywhere light, short-dashed arrows).

Temperature uniformity involves improvement by movement of radiating triatomic gases as well as convection poc. (See also chap. 5 of reference 51.) Concepts of this chapter will be facilitated by the following review of the laws of gas movement concerning buoyancy, velocity head, fluid friction between gases and solids, and flow induction. 

For each stage keep the exit temperature (T2-298) < 120-150 °C. For diatomic gases, k = 1.4, this limits compression ratio P2/P1) to 4 for triatomic gases, 6. 

Equations (2.15) through (2.17) also require a value of k, the heat capacity ratio. Table 2.6 provides selected values. For monotonic ideal gases, li = 1.67,for diatomic gases, k = 1.4 and for triatomic gases, k = 1.32. API (1996) recommends a value of 1.4 for screening purposes. 

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