A Novel Approach for Measurement of Composition and Temperature of N-Decane/Butanol Blends Using Two-Color Laser-Induced Fluorescence of Nile Red

Abstract

In this work, the possibility of using a two-color LIF (laser-induced fluorescence) approach for fuel composition and temperature measurements using nile red dissolved in n-decane/butanol blends is investigated. The studies were conducted in a specially designed micro cell enabling the detection of the spectral LIF intensities over a wide range of temperatures (283–423 K) and butanol concentrations (0–100 vol.%) in mixtures with n-decane. Furthermore, absorption spectra were analyzed for these fuel mixtures. At constant temperature, the absorption and LIF signals exhibit a large spectral shift toward higher wavelengths with increasing butanol concentration. Based on this fact, a two-color detection approach is proposed that enables the determination of the butanol concentration. This is reasonable when temperature changes and evaporation effects accompanied with dye enrichment can be neglected. For n-decane, no spectral shift and broadening of the spectrum are observed for various temperatures. However, for butanol admixture, two-color thermometry is possible as long as the dye and butanol concentrations are kept constant. For example, the LIF spectrum shows a distinct broadening for B20 (i.e., 80 vol.% n-decane, 20 vol.% butanol) and a shift of the peak toward lower wavelengths of about 40 nm for temperature variations of 140 K.

A novel laser-induced fluorescence concept for thermometry measurements in machining lubricoolants

“…A pressurized tank (2000 ml, pressure: 0.8 MPa) enabled refilling the preheated/precooled cell, since the investigated coolant dye mixtures are highly sensitive to photo bleaching. Further details of the micro cell used are described in [32,52].…”

“…Nile red can be dissolved in non-polar solvents like iso-octane, kerosene, Fragoltherm F12 and Marlotherm LH and can be utilized for the determination of the mixture composition of e.g. butanol/decane and ethanol/isooctane mixtures [32,33]. Nile red fluorescence shows a high temperature sensitivity when dissolved in kerosene and biofuel blends, while it is less temperature sensitive in fuels such as E20 (80 vol.% iso-octane, 20 vol.% ethanol) and E40 [16].…”

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

“…A connected pressurized tank (0.8 MPa) enabled refilling the preheated/precooled cell in the case of photo bleaching sensitive liquid tracer mixtures. Further details of the measurement cell used are described in [57,59,79].…”

“…Nile red (C 20 H 18 N 2 O 2 , Sigma Aldrich: Bellefonte, PA, USA,) is a well-known fluorophore; the applications of Nile red were initially based in microfluidic systems and biology [85][86][87]. Recent studies utilized the tracer for planar droplet sizing of fuel sprays [57,59,88]. Its aromatic ring structure features polar substituents.…”

“…Coumarin is mainly used for two-color LIF thermometry in ethanol [42]. Nile red was proposed as a dye for thermometry in ethanol/iso-octane mixtures; it can be utilized for the determination of the composition of butanol/decane mixtures [57,58]. Nile red is less temperature sensitive in fuels such as E20 (80 vol.% iso-octane, 20 vol.% ethanol) and E40, while it shows a high temperature sensitivity for kerosene and its biofuel blends [59].…”