Radiation Transfer through Gases
This chapter focuses on how to derive volumetric absorption; geometric mean beam length; radiation transfer between gray gases at a uniform temperature. By using electric network analogy, it provides several relevant engineering applications such as radiation transfer between gas at a high uniform temperature and one-surface furnace assuming the gray diffuse surface at a low uniform temperature; or between gas at a high uniform temperature and two-surfaces furnace assuming gray diffuse surfaces with each surface at different low uniform temperatures. The chapter discusses one-dimensional varying gas temperature, steady-state, and gray diffuse surface problem. In general, gas emissivity and absorptivity increase with pressure and volume, but decrease with temperature; gas emissivity and absorptivity vary with wavelength. Gases absorb and emit radiation in rather narrow wavelength bands rather than in the continuous spectrum exhibited by solid surfaces. In some applications, such as cryogenic thermal insulation, radiation heat is transferred from surface 1 to surface 2 through participating gases with varying temperature.