Scaling rules for total absorptivity and emissivity of gases

The functional relationships between total and spectral molecular-gas radiation properties are investigated to derive a generalized rule for estimating the total absorptivity of a homogeneous gas from a 1-atm-total-emissivity chart or expression. Tables of pressure-scaling exponents for different temperatures, pressures, path-length pressure products, and H2O/CO2/N2 mixtures are presented, and techniques for both exact (within the mean-beam-length approximation) and approximate calculations are explained and demonstrated. Allowance is made for reflecting walls in the gas/wall radiative-heat-transfer calculation. The rule and scaling tables are intended to replace the limited-applicability rules of Penner (1959) and Hottel and Sarofim (1967) in the computation of heat-transfer problems.