scholarly journals Measurement of Temperature and H2O Concentration in Premixed CH4/Air Flame Using Two Partially Overlapped H2O Absorption Signals in the Near Infrared Region

2021 ◽  
Vol 11 (8) ◽  
pp. 3701
Author(s):  
Sunghyun So ◽  
Nakwon Jeong ◽  
Aran Song ◽  
Jungho Hwang ◽  
Daehae Kim ◽  
...  
Keyword(s):  
Diode Laser ◽  
Absorption Spectroscopy ◽  
High Speed ◽  
Equivalence Ratio ◽  
Tunable Diode Laser ◽  
Laser Absorption Spectroscopy ◽  
Laser Absorption ◽  
Voigt Fitting ◽  
Diode Laser Absorption ◽  
Combustion Environment

It is important to monitor the temperature and H2O concentration in a large combustion environment in order to improve combustion (and thermal) efficiency and reduce harmful combustion emissions. However, it is difficult to simultaneously measure both internal temperature and gas concentration in a large combustion system because of the harsh environment with rapid flow. In regard, tunable diode laser absorption spectroscopy, which has the advantages of non-intrusive, high-speed response, and in situ measurement, is highly attractive for measuring the concentration of a specific gas species in the combustion environment. In this study, two partially overlapped H2O absorption signals were used in the tunable diode laser absorption spectroscopy (TDLAS) to measure the temperature and H2O concentration in a premixed CH4/air flame due to the wide selection of wavelengths with high temperature sensitivity and advantages where high frequency modulation can be applied. The wavelength regions of the two partially overlapped H2O absorptions were 1.3492 and 1.34927 μm. The measured signals separated the multi-peak Voigt fitting. As a result, the temperature measured by TDLAS based on multi-peak Voigt fitting in the premixed CH4/air flame was the highest at 1385.80 K for an equivalence ratio of 1.00. It also showed a similarity to those tendencies to the temperature measured by the corrected R-type T/C. In addition, the H2O concentrations measured by TDLAS based on the total integrated absorbance area for various equivalent ratios were consistent with those calculated by the chemical equilibrium simulation. Additionally, the H2O concentration measured at an equivalence ratio of 1.15 was the highest at 18.92%.

CO Concentration Measurement in the High Temperature Flame With Tunable Diode Laser Absorption Spectroscopy

2011 ◽  
Author(s):  
Ting Xu ◽  
Fei Wang ◽  
Zhishen Jiang ◽  
Jianhua Yan ◽  
Kefa Cen ◽  
...  
Keyword(s):  
High Temperature ◽  
Diode Laser ◽  
Absorption Spectroscopy ◽  
Equivalence Ratio ◽  
Tunable Diode Laser ◽  
Laser Absorption Spectroscopy ◽  
Laser Absorption ◽  
Co Concentration ◽  
Diode Laser Absorption ◽  
Combustion Environment

CO concentration real-time monitoring in combustion process has great significance in improving combustion efficiency and controlling combustion emissions. No CO-spectroscopy solid state sensors are available at the high temperature of 1600K–2000K in the flames. Gas sensing based on tunable diode laser absorption spectroscopy (TDLAS) with the advantages of high sensitivity, high selectivity, quick response and non-intrusiveness offers the possibility for on-line measurement in combustion environment. CO absorption line located at 2302.12nm is selected for measurement by direct absorption method in premixed C3H8/Air flat flame. Experiment results show that, when equivalence ratio is larger than one, the concentration of CO in the flame is increased with the increase of equivalence ratio. It proves that this method can be used on combustion environment.

scholarly journals Detection Limit of CO Concentration Measurement in LPG/Air Flame Flue Gas Using Tunable Diode Laser Absorption Spectroscopy

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4234
Author(s):  
Sunghyun So ◽  
Jiyeon Park ◽  
Aran Song ◽  
Jungho Hwang ◽  
Miyeon Yoo ◽  
...  
Keyword(s):  
Detection Limit ◽  
Diode Laser ◽  
Absorption Spectroscopy ◽  
Equivalence Ratio ◽  
Tunable Diode Laser ◽  
Laser Absorption Spectroscopy ◽  
Laser Absorption ◽  
Co Concentration ◽  
Diode Laser Absorption ◽  
Combustion Environment

In a combustion reaction of hydrocarbon fuel, carbon monoxide (CO) is a gas species that is closely related to air pollution generation and combustion efficiency. It has a trade-off with nitrogen oxide and increases rapidly in case of incomplete combustion or in fuel-rich (Φ > 1) environments. Therefore, it is essential to measure CO concentration in order to optimize the combustion condition. In the case of a steel annealing system, the combustion environment is maintained in a deoxidation atmosphere to prevent the formation of an oxide layer on the steel sheet surface. However, it is difficult to measure the CO concentration in a combustion furnace in real-time because of the harsh environment in the furnace. Tunable diode laser absorption spectroscopy, which has the advantages of non-invasiveness, fast response, and in situ measurement-based optical measurement, is highly attractive for measuring the concentration of a certain gas species in a combustion environment. In this study, a combustion system of a partially premixed flamed burner was designed to control the equivalence ratio for fuel-rich conditions. CO concentration was measured using a distributed feedback laser with a wavenumber of 4300.7 cm−1 in the mid-infrared region. The results showed that the CO concentration measured at an equivalence ratio of 1.15 to 1.50 was 0.495% to 6.139%. The detection limit in the combustion environment was analyzed at a path length of 190 cm and an internal temperature of 733 K. The ranges of the peak absorbance were derived as 0.064 and 0.787, which were within the theoretical bounds of 10−3 and 0.80 when the equivalence ratio was varied from 1.15 to 1.50.

scholarly journals On the methodology of measuring high-speed flows using tunable diode laser absorption spectroscopy

2012 ◽  
Vol 61 (3) ◽  
pp. 034214
Author(s):  
Zhang Liang ◽  
Liu Jian-Guo ◽  
Kan Rui-Feng ◽  
Liu Wen-Qing ◽  
Zhang Yu-Jun ◽  
...  
Keyword(s):  
Diode Laser ◽  
Absorption Spectroscopy ◽  
High Speed ◽  
Tunable Diode Laser ◽  
Laser Absorption Spectroscopy ◽  
Laser Absorption ◽  
Diode Laser Absorption ◽  
High Speed Flows

A Fire Warning Method Using Tunable Diode Laser Absorption Spectroscopy

2021 ◽  
Vol 16 (2) ◽  
pp. 222-229
Author(s):  
Lin Feng ◽  
Jian Wang ◽  
Chao Ding
Keyword(s):  
Diode Laser ◽  
Absorption Spectroscopy ◽  
Gas Absorption ◽  
Tunable Diode Laser ◽  
Laser Absorption Spectroscopy ◽  
Gas Concentration ◽  
Laser Absorption ◽  
Output Wavelength ◽  
Light Beams ◽  
Diode Laser Absorption

Tunable diode laser absorption spectroscopy (TDLAS) technology is adopted herein to detect fire gas produced in the early stage of the fire. Based on this technology, a fire warning detection system with multiple lasers and detectors is proposed. Multiple drivers input laser’s temperature and injected current data, making its output wavelength consistent with the measured gas’ absorption peak wavelengths in absorption spectroscopy. Multiple light beams are coupled to the same optical fiber. After the light beams pass through the long optical path absorption cell filled with fire gas, the beams are separated by a converter. The signals are demodulated by different detectors and further analyzed for fire warnings. After the fire warning system’s design, the system’s various hardware modules are designed, including the light source module, TDLAS controller, gas chamber module, photoelectric detector, and data collection. When the temperature remains unchanged, the output wavelength is linearly related to the injected current. When the injected current remains unchanged, the output wavelength is linearly related to the operating temperature. With a semiconductor laser’s injected current of 40 mA, the initial temperature of 38.6 °C, and the output wavelength of 1578.16 nm, the output wavelength increases continuously as the temperature increases. The harmonic signal amplitude after gas absorption is positively correlated with the measured gas concentration, indicating that the second harmonic signals can estimate the fire gas concentration.

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