Exciplex Fluorescence Thermometry of Liquid Fuel

Abstract

An experimental program is described that investigates the application of exciplex fluorescence to the internal thermometry of flowing liquid decane in the temperature range 24–91°C. Decane is doped with pyrene and excited by laser radiation at 354.7 nm. A library of temperature-dependent, exciplex fluorescence spectra is obtained from a static, isothermal solution, and the spectral features are analyzed to produce a temperature-prediction algorithm. The solution then flows through a temperature gradient region, and the laser-induced fluorescence spectra that are recorded are used to determine the local temperature in the solution by application of the algorithm. Excellent agreement between the predicted temperatures and those measured by thermocouples in contact with the solution is realized. The experiment demonstrates the high accuracy and spatial resolution obtainable with this laser-based thermometry technique.