Abstract
Conventional fossil fuels are of carbon-hydrogen composition. A number of alternative fuels, e.g., coal, lignite, are carbon-based fuels. The high temperature combustion of such fuels would generate carbon dioxide, and if hydrogen is present, water vapor. The knowledge of the emissivities of carbon dioxide and water vapor is very important in burner design and thermal efficiency calculations. The present work utilizes a gray-plus-clear gas model to approximate standard carbon dioxide emissivities. The model developed covers a temperature range of 300-1800 K and a pL range of 0.05 to 1000 cm atm. The results indicated that a mixture of six gray gases was adequate to cover the whole range. Comparison of calculated and tabulated results showed that in the range of industrial application, the present model has an error range of -4.2 to 5.9 percent. Comparison with Leckner's model shows the superiority of the present work.