In situ Raman imaging combined with computational fluid dynamics for measuring concentration profiles during mixing processes

Rinke, Günter; Wenka, A.; Roetmann, Karsten; Wackerbarth, Hainer

doi:10.1016/j.cej.2011.11.016

Cited by 9 publications

(4 citation statements)

References 21 publications

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“…Various kinds of two-dimensional measurements have been reported based on this imaging technique; e.g. visualization of mole-fraction distribution in a combustion chamber [38], thermometry of burner flame [39], dropsizing in a spray [40] and mixing analysis in a micro-mixer [41,42]. In our previous article [43], the Raman imaging technique was applied to micro-scale channel water flow for temperature measurements by using a single camera and two different optical filters.…”

Section: Two-wavelength Raman Imaging For Non-intrusive Monitoring Of...mentioning

confidence: 99%

Two-wavelength Raman imaging for non-intrusive monitoring of transient temperature in microfluidic devices

Kuriyama

Sato

2014

Meas. Sci. Technol.

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The present study proposes a non-intrusive visualization technique based on two-wavelength Raman imaging for in-situ monitoring of the unsteady temperature field in microfluidic systems. The measurement principle relies on the contrasting temperature dependencies of hydrogen-bonded and non-hydrogen-bonded OH stretching modes of the water Raman band, whose intensities were simultaneously captured by two cameras equipped with corresponding bandpass filters. The temperature distributions were then determined from the intensity ratio of the simultaneously-obtained Raman images, which enables compensation for temporal fluctuation and spatial inhomogeneity of the excitation laser intensity. A calibration experiment exhibited a linear relationship between the temperature and the intensity ratio in the range 293–343 K and least-regression analysis gave an uncertainty of 1.43 K at 95% confidence level. By applying the calibration data, time series temperature distributions were quantitatively visualized in a Y-shaped milli-channel at a spatial resolution of 6.0 × 6.0 µm2 with an acquisition time of 16.5 s. The measurement result clearly exhibited the temporal evolution of the temperature field and was compared with the values obtained by thermocouples. This paper therefore demonstrates the viability of employing the two-wavelength Raman imaging technique for temperature measurements in microfluidic devices.

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Section: Two-wavelength Raman Imaging For Non-intrusive Monitoring Of...mentioning

confidence: 99%

Two-wavelength Raman imaging for non-intrusive monitoring of transient temperature in microfluidic devices

Kuriyama

Sato

2014

Meas. Sci. Technol.

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“…Thus, composition profiles in microfluidic devices have been measured for mixing processes [129,130], diffusion through interfaces [131][132][133], or chemical reactions [134][135][136][137]. Roetmann et al [138] and Rinke et al [139] were able to record 2D density maps (Raman "imaging") of mixing miniflows, with subsecond time resolution, by using pulsed (6 ns) excitation.…”

Section: Applications To Liquid Microflowsmentioning

confidence: 99%

Review of Optical Thermometry Techniques for Flows at the Microscale towards Their Applicability to Gas Microflows

et al. 2022

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Thermometry techniques have been widely developed during the last decades to analyze thermal properties of various fluid flows. Following the increasing interest for microfluidic applications, most of these techniques have been adapted to the microscale and some new experimental approaches have emerged. In the last years, the need for a detailed experimental analysis of gaseous microflows has drastically grown due to a variety of exciting new applications. Unfortunately, thermometry is not yet well developed for analyzing gas flows at the microscale. Thus, the present review aims at analyzing the main currently available thermometry techniques adapted to microflows. Following a rapid presentation and classification of these techniques, the review is focused on optical techniques, which are the most suited for application at microscale. Their presentation is followed by a discussion about their applicability to gas microflows, especially in confined conditions, and the current challenges to be overcome are presented. A special place is dedicated to Raman and molecular tagging thermometry techniques due to their high potential and low intrusiveness.

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“…The microfluidic technology has frequently been used at ambient pressure conditions for optical analyses in various systems intersecting material processing, biological, pharmaceutical, , and reacting systems , and for the investigation into mass transfer. − The small fluid volume however results in weak signals which especially had restricted the applicability of the Raman spectroscopy to a few special systems . Recently, a phase (state of mater) selective Raman technique was introduced by the authors that can measure the composition of alternating phases even in fast segmented (multiphase) flows phase-selectively .…”

mentioning

confidence: 99%

Determination of Vapor–Liquid Equilibrium Data in Microfluidic Segmented Flows at Elevated Pressures Using Raman Spectroscopy

et al. 2015

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A fast, noninvasive, and efficient analytical measurement strategy for the characterization of vapor-liquid equilibria (VLE) is presented, which is based on phase (state of matter) selective Raman spectroscopy in multiphase flows inside microcapillay systems (MCS). Isothermal VLE data were measured in binary and ternary mixtures composed of acetone, water, carbon dioxide or nitrogen at elevated pressures up to 10 MPa and temperatures up to 333 K. For validation, the obtained data were compared with literature data and reference measurements in a high-pressure variable volume cell. Additionally, the mixtures were investigated at temperatures and pressures where no data is available in literature to extend the high-pressure VLE database.

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In situ Raman imaging combined with computational fluid dynamics for measuring concentration profiles during mixing processes

Cited by 9 publications

References 21 publications

Two-wavelength Raman imaging for non-intrusive monitoring of transient temperature in microfluidic devices

Two-wavelength Raman imaging for non-intrusive monitoring of transient temperature in microfluidic devices

Review of Optical Thermometry Techniques for Flows at the Microscale towards Their Applicability to Gas Microflows

Determination of Vapor–Liquid Equilibrium Data in Microfluidic Segmented Flows at Elevated Pressures Using Raman Spectroscopy

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