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International Heat Transfer Conference 13

ISBN Druckformat: 1-56700-226-9 (CD)
ISBN Online: 1-56700-225-0

TEMPERATURE MEASUREMENTS OF BINARY EVAPORATING DROPLETS USING THREE COLOR LASER-INDUCED FLUORESCENCE

DOI: 10.1615/IHTC13.p21.20
page 12

C. Maqua
LEMTA-CNRS UMR, Vandoeuvre-lés-Nancy, France

Guillaume Castanet
UMR 7563, LEMTA, Universite de Lorraine, ENSEM, Vandoeuvre-les-Nancy, TSA 60604-54518 Vandoeuvre CEDEX, France

Fabrice Lemoine
Laboratoire d'Energetique et de Mecanique Theorique et Appliquee Institut National Polytechnique de Lorraine, Universite Henri Poincare - Nancy I 2, Avenue de la Foret de Haye BP 160, F-54504 Vandoeuvre-les-Nancy Cedex France

Abstrakt

The optimization of the combustion process of liquid commercial petroleum requires the fine understanding of multi-component droplet vaporization, especially when each component evaporates at different boiling temperature.
This paper presents the application of a novel technique to the study of the temperature of bi-component droplets along a monodisperse stream. Based on the three-color extension of the two-color laser-induced fluorescence (LIF) technique, mean droplet temperatures can be measured regardless of the composition. The method requires adding a fluorescent organic dye at low concentration to a fuel composed with a mixture of ethyl-alcohol and acetone. The ratio between the fluorescence signals collected on two spectral bands (having different temperature sensitivities) is then a function of the temperature, regardless of laser intensity, time-dependant tracer concentration, and measurement volume. In the case of binary droplets, the fluorescence signal depends on both temperature and composition. To overcome this problem, a third spectral band is used to calculate a second fluorescence signal ratio and separate the influence of composition and temperature, after proper calibration. The approximate overall accuracy is then of ± 1.3 °C. The technique is demonstrated on two experimental arrangements:

  • overheated droplets injected at ambient temperature: study of the influence of droplet diameter and spacing for different initial compositions on droplet temperature is performed.
  • droplets injected in a hot air plume: the study of the influence of the initial composition and droplet diameter is achieved.
In both experiments, the influence of the droplet initial composition on the thermal exchanges by forced convection and evaporation is highlighted.

IHTC-13 Digital Library

Measurement of fluid temperature with an arrangement of three thermocouples FLOW BOILING OF A HIGHLY VISCOUS POLYMER SOLUTION