In situ detection of potassium atoms in high-temperature coal-combustion systems using near-infrared-diode lasers

Schlosser, E.; Fernholz, T.; Teichert, H.; Ebert, Volker

doi:10.1016/s1386-1425(02)00049-5

Cited by 91 publications

(55 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(2) the dynamic tuning coefficient of the laser dν dt (which is a constant property of the individual laser) and fundamental physical constants such as the Boltzmann constant k B are needed to solve this equation. The first is derived experimentally using the airy signal of the laser light passing through a planar, air-spaced etalon (Ebert and Wolfrum, 2000;Schlosser et al, 2002). From long-term dν dt measurements over several years, we could verify, for the laser type used, a long-term stability of this basic laser property to better than 1 %, which is within the current uncertainties of the tuning characterisation.…”

Section: Discussionmentioning

confidence: 65%

Rapid, optical measurement of the atmospheric pressure on a fast research aircraft using open-path TDLAS

2014

View full text Add to dashboard Cite

Abstract. Because of the high travel speed, the complex flow dynamics around an aircraft, and the complex dependency of the fluid dynamics on numerous airborne parameters, it is quite difficult to obtain accurate pressure values at a specific instrument location of an aircraft's fuselage. Complex simulations using computational fluid dynamics (CFD) models can in theory computationally "transfer" pressure values from one location to another. However, for long flight patterns, this process is inconvenient and cumbersome. Furthermore, these CFD transfer models require a local experimental validation, which is rarely available.In this paper, we describe an integrated approach for a spectroscopic, calibration-free, in-flight pressure determination in an open-path White cell on an aircraft fuselage using ambient, atmospheric water vapour as the "sensor species". The presented measurements are realised with the HAI (Hygrometer for Atmospheric Investigations) instrument, built for multiphase water detection via calibration-free TDLAS (tunable diode laser absorption spectroscopy). The pressure determination is based on raw data used for H 2 O concentration measurement, but with a different post-flight evaluation method, and can therefore be conducted at deferred time intervals on any desired flight track.The spectroscopic pressure is compared in-flight with the static ambient pressure of the aircraft avionic system and a micro-mechanical pressure sensor, located next to the openpath cell, over a pressure range from 150 to 800 hPa, and a water vapour concentration range of more than 3 orders of magnitude. The correlation between the micro-mechanical pressure sensor measurements and the spectroscopic pressure measurements shows an average deviation from linearity of only 0.14 % and a small offset of 9.5 hPa. For the spectroscopic pressure evaluation we derive measurement uncertainties under laboratory conditions of 3.2 and 5.1 % during inflight operation on the HALO airplane. Under certain flight conditions we quantified, for the first time, stalling-induced, dynamic pressure deviations of up to 30 % (at 200 hPa) between the avionic sensor and the optical and mechanical pressure sensors integrated in HAI. Such severe local pressure deviations from the typically used avionic pressure are important to take into account for other airborne sensors employed on such fast flying platforms as the HALO aircraft.

show abstract

Section: Discussionmentioning

confidence: 65%

Rapid, optical measurement of the atmospheric pressure on a fast research aircraft using open-path TDLAS

2014

View full text Add to dashboard Cite

show abstract

“…Many wavelength-agile sources have recently emerged, including vertical-cavity emitting lasers [1][2][3][4], thermally cycled diodes [5], chirped white pulses [6][7][8], variable Raman shifters [9], and scanning-grating systems [10]. The source presented in this paper is of the scanning-grating type.…”

Section: Introductionmentioning

confidence: 99%

Wavelength-agile sensor applied for HCCI engine measurements

Kranendonk

Walewski

Kim

et al. 2005

Proceedings of the Combustion Institute

View full text Add to dashboard Cite

“…) carried by the gas to be analyzed. These capabilities were, for example, extensively demonstrated via measurements inside of combustion processes in industrial power plants (Ebert et al, 2000a;Schlosser et al, 2002;Sun et al, 2013;Teichert et al, 2003). TDLAS, especially in the near infrared spectral range, is a powerful as well as versatile diagnostic technique and has led to numerous applications in atmospheric hygrometry (Diskin et al, 2002;Fahey and Gao, 2009;Gurlit et al, 2005;May, 1998;Schiff et al, 1994;Thornberry et al, 2015).…”

Section: Direct Tunable Diode Laser Absorption Spectroscopymentioning

confidence: 99%

“…The term dν dt is called the dynamic tuning coefficient of the used laser. It can be determined experimentally and is directly linked to the SI units (length) by using the Airy signal of the laser light passing through a planar, air-spaced etalon (Ebert and Wolfrum, 2000;Schlosser et al, 2002). However, unpublished, on-going, and long-term dν dt measurements for the 1.37 µm distributed feedback (DFB) laser type used over several years indicate a long-term stability of its tuning characteristics better than 1 %, which is within the current uncertainties of the tuning characterization.…”

Section: Non-calibrated Dtdlasmentioning

confidence: 99%

HAI, a new airborne, absolute, twin dual-channel, multi-phase TDLAS-hygrometer: background, design, setup, and first flight data

et al. 2017

View full text Add to dashboard Cite

Abstract. The novel Hygrometer for Atmospheric Investigation (HAI) realizes a unique concept for simultaneous gas-phase and total (gas-phase + evaporated cloud particles) water measurements. It has been developed and successfully deployed for the first time on the German HALO research aircraft. This new instrument combines direct tunable diode laser absorption spectroscopy (dTDLAS) with a firstprinciple evaluation method to allow absolute water vapor measurements without any initial or repetitive sensor calibration using a reference gas or a reference humidity generator. HAI contains two completely independent dual-channel (closed-path, open-path) spectrometers, one at 1.4 and one at 2.6 µm, which together allow us to cover the entire atmospheric H 2 O range from 1 to 40 000 ppmv with a single instrument. Both spectrometers each comprise a separate, wavelength-individual extractive, closed-path cell for total water (ice and gas-phase) measurements. Additionally, both spectrometers couple light into a common open-path cell outside of the aircraft fuselage for a direct, sampling-free, and contactless determination of the gas-phase water content. This novel twin dual-channel setup allows for the first time multiple self-validation functions, in particular a reliable, direct, in-flight validation of the open-path channels. During the first field campaigns, the in-flight deviations between the independent and calibration-free channels (i.e., closed-path to closed-path and open-path to closed-path) were on average in the 2 % range. Further, the fully autonomous HAI hygrometer allows measurements up to 240 Hz with a minimal integration time of 1.4 ms. The best precision is achieved by the 1.4 µm closed-path cell at 3.8 Hz (0.18 ppmv) and by the 2.6 µm closed-path cell at 13 Hz (0.055 ppmv). The requirements, design, operation principle, and first in-flight performance of the hygrometer are described and discussed in this work.

show abstract

In situ detection of potassium atoms in high-temperature coal-combustion systems using near-infrared-diode lasers

Cited by 91 publications

References 10 publications

Rapid, optical measurement of the atmospheric pressure on a fast research aircraft using open-path TDLAS

Rapid, optical measurement of the atmospheric pressure on a fast research aircraft using open-path TDLAS

Wavelength-agile sensor applied for HCCI engine measurements

HAI, a new airborne, absolute, twin dual-channel, multi-phase TDLAS-hygrometer: background, design, setup, and first flight data

Contact Info

Product

Resources

About