Simultaneous measurements of temperature and CO2 concentration employing diode laser absorption near 2.0 μm

Simultaneous measurements of gas temperature and CO2 concentration in combustion gases using an extended-wavelength diode laser sensor at 2.0 μm are reported. A CO2 transition pair located near 5,006.140 and 5,010.725 cm−1 is selected based on existing line-selection criteria. The gas temperature and CO2 concentration are inferred from the peak heights of the 1f-normalized WMS-2f signals. Some important factors (modulation depth, total pressure, and species concentration) influencing the performance of the sensor are discussed. Validation experiments performed in a heated static cell indicated that the sensor has accuracies of 1.21 and 2.98 % for temperature and CO2 concentration measurement. The demonstration in combustion gases produced by a burner illustrates the potential of the 1f-normalized WMS-2f sensor for combustion diagnosis.