Near infrared spectral radiation properties of different liquid hydrocarbon fuels

A double-thickness transmission model for a three-layer structure combined with a genetic algorithm was adopted to determine the spectral radiation properties of liquids. The reliability of this model was illustrated by the good agreement between the optical constants measured and that from the references. Then the spectral radiation properties of three typical liquid hydrocarbon fuels (diesel, gasoline, and jet fuel) available in China were measured in the wavelength range of 1000–2100？nm from room temperature to 423？K. Results indicate that the optical constants of these fuels are related to the fuel composition, wavelength, and temperature. At room temperature, the absorption index of the low carbon fuel (gasoline) was smaller than that for the high carbon fuels (diesel and jet fuel) in the wavelength range of 1100–1450？nm and 1700–2000？nm and larger in other bands. From room temperature to 423？K, the absorption index increased with temperature by a maximum rate of 50% per degree for the low carbon fuel, while it presents different trends for the high carbon fuel. The absorption index of the diesel decreased with temperature by a maximum rate of 40% per degree, while there exists a turning point for that of jet fuel at 1685？nm. For all these fuels, the temperature influence on the refractive index was not obvious, as the changing rate only reaches up to 3% per degree