Simultaneous measurement on gas concentration and particle mass concentration by tunable diode laser

Wang, F.; Cen, Kefa; Li, N.; Huang, Qunxing; Chao, Xing; Yan, Jun; Chi, Yong

doi:10.1016/j.flowmeasinst.2010.04.009

Cited by 28 publications

(6 citation statements)

References 14 publications

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“…They used the transmitted laser intensity to calibrate the 2f signal to solve the problem of particle interference with gas measurements. A concentration of 20% carbon dioxide was measured, and the calibrated 2f peak error was less than 5% [19].…”

Section: Introductionmentioning

confidence: 99%

Correcting the light extinction effect of fly ash particles on the measurement of NO by TDLAS

et al. 2022

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The measurement of nitric oxide (NO) concentration in power plant flue gas by tunable diode laser absorption spectroscopy (TDLAS) is susceptible to fly ash particles. The presence of fly ash particles causes laser intensity fluctuations and leads to the second harmonic (2f) signal amplitude changes. In this manuscript, we analyzed the influence of particles on the 2f signal and corrected the measurement error of NO concentration by the wavelength modulation-second harmonic (WMS-2f) technique. Specifically, the 2f signal error caused by quartz sand and fly ash particles were measured, and the exponential function representing the peak-to-peak error of the 2f signal was obtained by fitting. Finally, the peak-to-peak value of the 2f signal and the NO concentration were corrected according to the exponential function. After correction, the NO concentration error under the fly ash influence (the particle size in the range of 10–200 μm and the mass concentration is less than 18.26 g/m3) was no more than 2%. This correction method effectively improves the measurement accuracy of NO concentration by the WMS-2f technique in the fly ash environment.

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Section: Introductionmentioning

confidence: 99%

Correcting the light extinction effect of fly ash particles on the measurement of NO by TDLAS

et al. 2022

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“…In 1980, Bjorklund proposed a method for measuring weak absorption and dispersion called frequency-modulation spectroscopy [12]. TDLAS with WMS enables alternating-current detection at a specific frequency and the use of a lock-in amplifier (LIA) for better signal recovery [13]- [15].…”

Section: Introductionmentioning

confidence: 99%

A DFB-LD Internal Temperature Fluctuation Analysis in a TDLAS System for Gas Detection

et al. 2019

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The temperature fluctuations inside commercially distributed feedback laser diode were experimentally measured and analyzed in detail in this study. In tunable diode laser absorption spectroscopy based gas sensing systems, the temperature of the laser source is usually fixed and a current signal is used to drive the laser for wavelength scanning or modulation. Even if the laser is controlled by a robust temperature controller, the internal temperature still fluctuates due to the delayed response of the temperature controller when rapidly changing the drive current. These temperature fluctuations result in distortions in the measured absorption signals which can be effectively suppressed by limiting the drive current modulation to the resonance frequency of the temperature control proportional-integral-derivative loop. This study demonstrates a reduction in the temperature dependent absorption distortions and improves the detection uncertainty using this technique.

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“…TDLS with wavelength modulation spectroscopy (WMS) enables alternating-current (AC) detection at some frequency of choice and the use of a lock-in amplifier (LIA) for better signal recovery [ 17 , 18 , 19 , 20 ]. Each harmonic signal is proportional to the concentration of target gas and can be measured with the LIA.…”

Section: Introductionmentioning

confidence: 99%

Modulation Index Adjustment for Recovery of Pure Wavelength Modulation Spectroscopy Second Harmonic Signal Waveforms

Wei

Chang

Wang

et al. 2017

Sensors

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A new technique of modulation index adjustment for pure wavelength modulation spectroscopy second harmonic signal waveforms recovery is presented. As the modulation index is a key parameter in determining the exact form of the signals generated by the technique of wavelength modulation spectroscopy, the method of modulation index adjustment is applied to recover the second harmonic signal with wavelength modulation spectroscopy. By comparing the measured profile with the theoretical profile by calculation, the relationship between the modulation index and average quantities of the scanning wavelength can be obtained. Furthermore, when the relationship is applied in the experimental setup by point-by-point modulation index modification for gas detection, the results show good agreement with the theoretical profile and signal waveform distortion (such as the amplitude modulation effect caused by diode laser) can be suppressed. Besides, the method of modulation index adjustment can be used in many other aspects which involve profile improvement. In practical applications, when the amplitude modulation effect can be neglected and the stability of the detection system is limited by the sampling rate of analog-to-digital, modulation index adjustment can be used to improve detection into softer inflection points and solve the insufficient sampling problem. As a result, measurement stability is improved by 40%.

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Simultaneous measurement on gas concentration and particle mass concentration by tunable diode laser

Cited by 28 publications

References 14 publications

Correcting the light extinction effect of fly ash particles on the measurement of NO by TDLAS

Correcting the light extinction effect of fly ash particles on the measurement of NO by TDLAS

A DFB-LD Internal Temperature Fluctuation Analysis in a TDLAS System for Gas Detection

Modulation Index Adjustment for Recovery of Pure Wavelength Modulation Spectroscopy Second Harmonic Signal Waveforms

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