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Wadekar, V Wagner equation, for vapour pressure, Wake, Coles law of the, Wall layer transmissivity, Wall temperature: Wallis correlations: Wallis criterion, for transition from stratified to annular flow, applications in condensation, Walz' method, for laminar boundary layers, Waste heat boilers, Waste water, fouling by, Water:
critical heat flux values for, in tubes (table), emissivity of gaseous,
Emissivity Data for Gases
fouling, design of heat exchangers for, liquid, properties of pool boiling curve for, at atmospheric pressure, quality, effect on fouling, saturated properties: supercritical properties of, superheated gaseous:
Watertube boiler, Wavelengths, of blackbody radiation, Waves, interfacial, effect on film condensation on vertical surface, Wavy fins, in plate fin exchangers, Webb, D R Webb, R L Weber, M, Weber number, Weil, C J Welded channel head, in shell-and tube heat exchanger, Welded fins: Welded plate exchangers: Welding: Welds: Wentz and Thodos equation, for fixed-bed pressure drop, Wet-bulb temperature, Wettability, of surface, effect on pool boiling, Whalley and Hewitt correlations: White-Metzner model, for non-Newtonian fluid, Wicks, for heat pipes: Wilday, A J Wildsmith, G, Wills-Johnson flow stream analysis method for segmentally baffled shell-and-tube heat exchangers, Wilson, D I Window zone, in shell-and-tube heat exchangers: Winter, H H, Wire matrix inserts, in heat exchangers, Wirth, K E, Wispy annular flow, regions of occurrence of, Work (in exergy analysis) Working fluid, selection of for heat pipe,

Index

HEDH
A B C D E F G H I J K L M N O P Q R S T U V W
Wadekar, V Wagner equation, for vapour pressure, Wake, Coles law of the, Wall layer transmissivity, Wall temperature: Wallis correlations: Wallis criterion, for transition from stratified to annular flow, applications in condensation, Walz' method, for laminar boundary layers, Waste heat boilers, Waste water, fouling by, Water:
critical heat flux values for, in tubes (table), emissivity of gaseous,
Emissivity Data for Gases
fouling, design of heat exchangers for, liquid, properties of pool boiling curve for, at atmospheric pressure, quality, effect on fouling, saturated properties: supercritical properties of, superheated gaseous:
Watertube boiler, Wavelengths, of blackbody radiation, Waves, interfacial, effect on film condensation on vertical surface, Wavy fins, in plate fin exchangers, Webb, D R Webb, R L Weber, M, Weber number, Weil, C J Welded channel head, in shell-and tube heat exchanger, Welded fins: Welded plate exchangers: Welding: Welds: Wentz and Thodos equation, for fixed-bed pressure drop, Wet-bulb temperature, Wettability, of surface, effect on pool boiling, Whalley and Hewitt correlations: White-Metzner model, for non-Newtonian fluid, Wicks, for heat pipes: Wilday, A J Wildsmith, G, Wills-Johnson flow stream analysis method for segmentally baffled shell-and-tube heat exchangers, Wilson, D I Window zone, in shell-and-tube heat exchangers: Winter, H H, Wire matrix inserts, in heat exchangers, Wirth, K E, Wispy annular flow, regions of occurrence of, Work (in exergy analysis) Working fluid, selection of for heat pipe,
X Y Z
W Water: emissivity of gaseous,
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Emissivity Data for Gases

DOI 10.1615/hedhme.a.000528

5.5 PHYSICAL PROPERTY DATA TABLES
5.5.5 Emissivity data for gases

D.K. Edwards and R. Matavosian

Table 1a, Table 1b, and Table 1c present the total emissivity of water vapor, carbon dioxide gas, and a mixture as a function of PaL and Tg. The quantity is the partial pressure of the absorbing gas, H2O or CO2; L is the beam length of concern; and Tg is the gas temperature. The tables for the individual gases are presented for an equivalent broadening pressure ratio Pe of 1. The ratio is defined in the footnote to Table 1a and accounts for the fact that collisions between absorbing molecules and foreign gas molecules are less effective in broadening the absorption lines than absorber-absorber collisions. In the case of Table 1c the total pressure of the mixture is 1 atm. and the absorber partial pressure Pa is that of the H2O component in the mixture.

The tables are based on the information contained in Table 5-1 of Section 208 in the manner illustrated there in the sample calculations.

The emissivity grows with PaL because at constant Ts the number of absorbing molecules increases as PaL increases. At low values of PaL the emission is weak, and each additional molecule adds equally to the absorption; hence εg is linear in PaL. At higher values the addition of greater opacity at the centers of the lines has little additional effect there, but more is emitted between the lines. The εg integrated over the lines grows as \(\sqrt{P_a L}\). At still higher values of PaL, the addition of greater opacity even between the lines near the center of the absorption-emission band has little additional effect there, and εg grows primarily in the tails of the bands, in total even more slowly. Logarithmic interpolation in Table 1a, Table 1b, and Table 1c is recommended as follows:

\(\epsilon_{g}(P_{a}L) = \epsilon_{g}(P_{a}L_{2})\left(\frac{P_{a}L}{P_{a}L_{2}}\right)^{n}\notag\)

\(n = \frac{\log[\epsilon_{g}(P_{a}L_{2})/\epsilon_{g}(P_{a}L_{1})]}{\log(P_{a}L_{2}/P_{a}L_{1})}\notag\)

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