Surface temperature measurements in a porous media burner using a new laser-induced phosphorescence intensity ratio technique

Abstract

Applying the laser-induced phosphorescence technique, the phosphorescence from a phosphor-coated surface can be used for the determination of the surface temperature during hydrocarbon fuel combustion in a porous media burner. A mixture of dysprosium–cerbium double-doped: yttrium aluminium garnet (Dy:Er:YAG) thermographic phosphor powder and an adhesive agent was used for coating the front surface of the burner which was operated with a thermal load of 1000 W and 2000 W and equivalence ratios of 0.7 and 0.8. A pulsed laser of 355 nm wavelength was used for phosphorescence excitation and a spectrometer for luminescence detections. An adapted intensity ratio (IR) method was applied for temperature determination and compared with two other IR methods. Temperature calibrations were executed in an oven which can be operated up to 2073 K. Imprecision and inaccuracy of the temperature measurements in the phosphor and the mixture calibrations and in the burner-coated front surface have been investigated. The adapted IR method allowed temperature measurements which were more accurate than the other two IR methods, applied for comparison. Compared to additionally performed thermocouple measurements and to published results in the literature using an infrared camera, the adapted IR method turned out to be the more accurate one. The temperature results were also in good agreement with numerical simulations given in the literature.