Characterization of the fluorescence properties of selected organic compounds for measuring the thickness of evaporating liquid fuel films

Geiler, Jan N.; Mirschinka, Florian; Kaiser, Sebastian

doi:10.1007/s00340-021-07651-4

Cited by 2 publications

(1 citation statement)

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“…Common tracers for studying the mixture formation and temperature in the gas phase are acetone, 3-pentanone, anisole, toluene, 1-methylnaphthalene, and triethylamine [35][36][37][38]. However, in the liquid phase, these tracers show only a low temperature sensitivity so that they are probably not applicable for thermometry (see, e.g., Geiler et al) [39]. Furthermore, these tracers are excited in the UV range, which may overlap with the absorption spectrum of the solvents (e.g., of heat transfer oils; see Appendix A, Figure A1).…”

Section: Introductionmentioning

confidence: 99%

Characterization of Fluorescence Tracers for Thermometry and Film Thickness Measurements in Liquid Coolants Relevant for Thermal Management of Electric and Electronic Components

Koegl

Delwig

Zigan

2022

Sensors

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This study investigated a novel two-color LIF (laser-induced fluorescence) technique for thermometry in coolants relevant for electric components. In principle, this diagnostic enables thermometry in liquid flows but also a simultaneous determination of film thickness and film temperature, which is relevant, e.g., for jet impingement cooled electric components. Temperature measurements are based on a temperature-sensitive intensity ratio of special tracers realized by suitable band pass filters within the respective emission spectra. For this purpose, the heat transfer fluids Fragoltherm F12, Marlotherm LH, and a water–glycol mixture WG20 (80 vol.% water, 20 vol.% glycol) and its individual components were doped with suitable tracers. The tracer Eosin-Y was utilized for polar coolants (water, WG20, and glycol) and Nile red was utilized for non-polar solvents (Fragoltherm F12 and Marlotherm LH). The spectral LIF intensities were recorded for a wide range of temperatures (253–393 K), which are relevant for cooling of electric motors, batteries, and power electronics. Furthermore, absorption spectra were analyzed as well. The temperature-dependent fluorescence measurements revealed different behavior for the polar and non-polar solvents. A temperature increase in the polar solvents (water, WG20, glycol) led to a spectral shift of the emission peaks of Eosin-Y towards longer wavelengths (red-shifted), while the peaks of Nile red in the non-polar solvents (Fragoltherm F12 and Marlotherm LH) showed an opposite behavior and were blue-shifted. The highest average temperature sensitivity was achieved for Marlotherm LH (4.22%/K), followed by glycol (1.99%/K), WG20 (1.80%/K), water (1.62%/K), and Fragoltherm F12 (1.12%/K). These sensitivities are similar to or even much higher than the literature data of other LIF tracers, which were, however, not determined in those coolants. Consequently, the two novel proposed dyes for the studied heat transfer liquids enable a reliable temperature determination.

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