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8 April 1996 Combustion control using a multiplexed diode-laser sensor system
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A multiplexed diode-laser sensor system, comprised of two InGaAsP diode lasers and fiber- optic components, has been developed to non-intrusively measure temperature and species concentration over a single path for closed-loop process control using laser absorption spectroscopy techniques. The system was applied to measure and control the gas temperature in the post-flame gases 6 mm above the surface of a Hencken burner (multiple CH4-air diffusion flames). The wavelengths of the lasers were independently current-tuned across H2O transitions near 1343 nm (v1 + v3 band) and 1392 nm (2v1, v1 + v3 bands), and temperature was determined from the ratio of measured peak absorbances. H2O concentration was determined from the measured peak absorbance of one transition set at the measured temperature. The temperatures recorded using the sensor compared well with those measured by thermocouples. A computer-controlled closed-loop feedback circuit that actuated the fuel flow in response to the difference between the measured and desired gas temperature was used to control the flame temperature in the probed region. The results obtained with this first generation system demonstrate the potential of multiplexed diode lasers for rapid, continuous, in situ measurements and control of gasdynamic parameters in combustion environments.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Douglas S. Baer, E. R. Furlong, and Ronald K. Hanson "Combustion control using a multiplexed diode-laser sensor system", Proc. SPIE 2703, Lasers as Tools for Manufacturing of Durable Goods and Microelectronics, (8 April 1996);

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