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This paper reports the development of vapor/liquid visualization systems based on an exciplex (excited state complex) formed between dimethyl- or diethyl-substituted aniline and trimethyl-substituted naphthalenes. Quantum yields of individual monomers were measured and the exciplex emission spectra as well as fluorescence quenching mechanisms were analyzed. Among the many systems and formulations investigated in this study, an exciplex consisting of 7% 1,4,6-trimethylnaphthalene (TMN) and 5% N,N-dimethylaniline (DMA) in 88% isooctane was found to be the best system for the laser-induced exciplex fluorescence (LIEF) technique, which is used to observe mixture formation in diesel or spark ignition (SI) engines. Observation of spectrally separated fluorescence from monomer in the gas phase and from exciplex in the gasoline fuel [1] requires that the exciplex forming dopants have boiling points within the distillation range of gasoline (20 to 215°C).

Increasing oil prices and more stringent emission laws require an improved efficiency from future automotive engines. Additionally, the competition of the automotive market demands longer service intervals and engine life-times. A potential to decrease the specific fuel consumption and improve specific volume is offered by means of increasing engine speed and maximum cylinder pressure. Hence, the mechanical stress on the tribological system including the piston, piston rings, cylinder liner, are increased and the reliability decreases. The objective of this research is the development of a mathematical model implemented in software, which can deliver a prediction of piston ring wear in internal combustion engines. The program has been applied to a top compression piston ring of a turbo charged Diesel engine at WOT operation conditions.