Temperature and multi-species measurements by supercontinuum absorption spectroscopy for IC engine applications

Abstract

Abstract:The first supercontinuum (SC) absorption spectroscopy measurements showing the feasibility of quantitative temperature evaluation are presented to the best of the authors' knowledge. Temperature and multi-species measurements were carried out at a detection rate of ∼2 MHz in a high-temperature flow cell within a temperature range from 450 K to 750 K at 0.22 MPa, representing conditions during the suction and compression stroke in an internal combustion (IC) engine. The broadband SC pulses were temporally dispersed into fast wavelength sweeps, covering the overtone absorption bands 2ν 1 , 2ν 3 , ν 1 + ν 3 of H 2 O and 3ν 3 of CO 2 in the near-infrared region from 1330 nm to 1500 nm. The temperature information is inferred from the peak ratio of a temperature sensitive (1362.42 nm) and insensitive (1418.91 nm) absorption feature in the ν 1 + ν 3 overtone bands of water. The experimental results are in very good agreement with theoretical intensity ratios calculated from absorption spectra based on HiTran data. 521-532 (2012). 9. S. T. Sanders, "Wavelength-agile fiber laser using group-velocity dispersion of pulsed super-continua and application to broadband absorption spectroscopy," Appl. Phys. B 75, 799-802 (2002). 10. A. R. Alfano (ed.), The Supercontinuum Laser Source (Springer, 2006). 11. J. C. Knight, T. A. Birks, P. St. J. Russell, and D. M. Atkin, "All-silica single-mode optical fiber with photonic crystal cladding," Opt. Lett. 21, 1547Lett. 21, -1549Lett. 21, (1996. 12. S. Roy and P. R. Chaudhuri, "Supercontinuum generation in visible to mid-infrared region in square-lattice photonic crystal fiber made from highly nonlinear glasses," Opt.

Towards simultaneous calibration-free and ultra-fast sensing of temperature and species in the intrapulse mode

“…Although studies have shown promise, the restriction to the near-infrared wavelength region, as well as the inherent shot-to-shot fluctuations, reduces the SNR. This demands considerable bin-averages in excess of 1000 pulses, as seen in the work of Sanders [18] and Werblinski et al [19], consequently compromising effective time resolutions of such sensors to well below 50 kHz. The typical chirp rates in these supercontinuum lasers are four orders of magnitude larger than that of chirped semiconductor lasers.…”

Recent Advances in the Characterization of Gaseous and Liquid Fuels by Vibrational Spectroscopy

“…An overview of the generation of SC radiation and its use in chemical sensing including the detection of typical fuel molecules was given by Kaminski et al [135]. So far, most work using SC absorption spectroscopy focused on sensing selected species such as water, carbon dioxide and small hydrocarbons in the gas phase, see for example [135][136][137][138][139]. However, future developments in this area may lead to methods for comprehensive fuel characterization.…”

Laser absorption spectroscopy for combustion diagnosis in reactive flows: A review

“…Furthermore, a significant improvement on the temperature sensitivity can be realized by scanning the wavelength over multiple absorption transitions. The broad spectral coverage facilitates the optimization of the sensitivity in different temperature ranges and used to be fitted against spectral databases for determination of combustion parameters (48,81,82).…”

“…The laser sources could perform better with customized designs for specific applications. Nowadays, the tunable laser sources are compact, reliable and relatively cheap, and thus make LAS widely applied to combustion diagnosis in various areas, such as engines monitoring and design (43,(48)(49)(50)(51), gas phase analysis in shock tubes (52)(53)(54)(55) and power plant exhaust monitoring (56)(57)(58).…”