scholarly journals Laser-Based, Optical, and Traditional Diagnostics of NO and Temperature in 400 kW Pilot-Scale Furnace

2021 ◽  
Vol 11 (15) ◽  
pp. 7048
Author(s):  
Alexey Sepman ◽  
Christian Fredriksson ◽  
Yngve Ögren ◽  
Henrik Wiinikka
Keyword(s):  
Pilot Scale ◽  
Uv Absorption ◽  
Gas Temperature ◽  
Spectral Fitting ◽  
Laser Absorption ◽  
Tuneable Diode Laser ◽  
Diode Laser Absorption ◽  
No Sensor ◽  
Probe Measurements ◽  
Better Than

A fast sensor for simultaneous high temperature (above 800 K) diagnostics of nitrogen oxide (NO) concentration and gas temperature (T) based on the spectral fitting of low-resolution NO UV absorption near 226 nm was applied in pilot-scale LKAB’s Experimental Combustion Furnace (ECF). The experiments were performed in plasma and/or fuel preheated air at temperatures up to 1550 K, which is about 200 K higher than the maximal temperature used for the validation of the developed UV NO sensor previously. The UV absorption NO and T measurements are compared with NO probe and temperature measurements via suction pyrometry and tuneable diode laser absorption (TDL) using H2O transitions at 1398 nm, respectively. The agreement between the NO UV and NO probe measurements was better than 15%. There is also a good agreement between the temperatures obtained using laser-based, optical, and suction pyrometer measurements. Comparison of the TDL H2O measurements with the calculated H2O concentrations demonstrated an excellent agreement and confirms the accuracy of TDL H2O measurements (better than 10%). The ability of the optical and laser techniques to resolve various variations in the process parameters is demonstrated.

Is mesophyll conductance to CO2 in leaves of three Eucalyptus species sensitive to short-term changes of irradiance under ambient as well as low O2?

2012 ◽  
Vol 39 (5) ◽  
pp. 435 ◽  
Author(s):  
Cyril Douthe ◽  
Erwin Dreyer ◽  
Oliver Brendel ◽  
Charles R. Warren
Keyword(s):  
Leaf Gas Exchange ◽  
Abiotic Factors ◽  
Eucalyptus Species ◽  
Mesophyll Conductance ◽  
Laser Absorption ◽  
Discrimination Model ◽  
Rapid Changes ◽  
Tuneable Diode Laser ◽  
Induced Changes ◽  
Diode Laser Absorption

Mesophyll conductance to CO2 (g m) limits the diffusion of CO2 to the sites of carboxylation, and may respond rapidly (within minutes) to abiotic factors. Using three Eucalyptus species, we tested the rapid response of g m to irradiance under 21% and 1% O2. We used simultaneous measurements of leaf gas exchange and discrimination against 13CO2 with a tuneable diode laser absorption spectrometer. Measurements under 1% O2 were used to limit uncertainties due to 13C–12C fractionation occurring during photorespiration. Switching irradiance from 600 to 200 µmol m–2 s–1 led to a ≈60% decrease of g m within minutes in all species under both 21% O2 and 1% O2. The g m response to irradiance is unlikely to be a computation artefact since using different values for the parameters of the discrimination model changed the absolute values of g m but did not affect the relative response to irradiance. Simulations showed that possible rapid changes of any parameter were unable to explain the observed variations of g m with irradiance, except for13C–12C fractionation during carboxylation (b), which, in turn, is dependent on the fraction of leaf C assimilated by phospho-enol pyruvate carboxylase (PEPc) (β). g m apparently increased by ≈30% when O2 was switched from 21% to 1% O2. Again, possible changes of β with O2 could explain this apparent g m response to O2. Nevertheless, large irradiance or O2-induced changes in β would be required to fully explain the observed changes in g m, reinforcing the hypothesis that g m is responsive to irradiance and possibly also to O2.

scholarly journals Research on Spectroscopy Modulation of a Distributed Feedback Laser Diode Based on the TDLAS Technique

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Bin Li ◽  
Liang Xue ◽  
Nan Ji ◽  
Da Hui Wei
Keyword(s):  
Diode Laser ◽  
Light Source ◽  
Absorption Spectroscopy ◽  
Laser Diode ◽  
Power Supply ◽  
Distributed Feedback ◽  
Distributed Feedback Laser ◽  
Laser Absorption ◽  
Tuneable Diode Laser ◽  
Diode Laser Absorption

Laser current and temperature control circuits have been developed for a distributed feedback laser diode, which is applied as the light source of a tuneable diode laser absorption spectroscopy system. The laser’s temperature fluctuation can be limited within the range of −0.02 to 0.02°C, and good operation stability was observed through 15 hours of monitoring on the emitting wavelength of the laser. Response time of temperature modulation was tested which is suitable for the tuning requirements of gas detection systems. Laser current can be injected within the range from 40 to 80 mA. In addition, a linear power supply circuit has been developed to provide stable and low-noise power supply for the system. The physical principles of laser modulation theory are discussed before experiments. Experiments show that the output wavelength of the laser can be tuned accurately through changing the working current and temperature. The wavelength can be linearly controlled by temperature at 0.115 nm/°C (I = 70 mA) and be controlled by current at 0.0140 nm/mA (T = 25°C). This is essential for the tuneable diode laser absorption spectroscopy systems. The proposed cost-effective circuits can replace commercial instruments to drive the laser to meet the requirements of methane detection experiments. It can also be applied to detect other gases by changing the light source lasers and parameters of the circuits.

A Measurement Based on Tunable Diode Laser Absorption Spectroscopy for Pressure in Gas Flow

2014 ◽  
Vol 1051 ◽  
pp. 910-914
Author(s):  
Song Ji Peng ◽  
Yan Ji Hong ◽  
Guang Yu Wang ◽  
Hu Pan
Keyword(s):  
Diode Laser ◽  
Absorption Spectroscopy ◽  
Gas Flow ◽  
Gas Pressure ◽  
Tunable Diode Laser ◽  
Measuring System ◽  
Gas Temperature ◽  
Laser Absorption Spectroscopy ◽  
Laser Absorption ◽  
Diode Laser Absorption

Pressure is a very important parameter for combustion diagnostics since pressure is a good indicator of combustion efficiency .As combustion technologies mature, more accurate and less response time pressure diagnosis are needed. Line of sight (LOS) tunable diode laser absorption spectroscopy (TDLAS) provides a fast, nonintrusive, sensitive and reliable solution for quantitative sensing of multiple flow field parameters including gas temperature, components concentration, and mass flux. So far, there is no mature method to measure gas pressure using TDLAS, and it is very important to perfect TDLAS measuring system with the gain of pressure.This paper intends to found a method based on TDLAS for gas pressure measurement. At first, a gas pressure measuring method is presented. Then, an experiment is conducted in a heated static cell to verify this method. A Direct-Absorption-Based Senor which scans H2O transitions near 1.4 μm was used, and this made the measuring system compact, low cost, simple to operate and quick to response. The experiment successfully measured the pressure in several pressure points, and the results agreed well with the data measured by pressure sensor, average difference is 3.1%.

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