Dynamic Oil Consumption Measurement of Internal Combustion Engines using Laser Spectroscopy

Abstract

A new approach has been developed to measure dynamic consumption of lubricant oil in an internal combustion engine. It is based on the already known technique where sulfur is used as a natural tracer of the engine oil. Since ejection of motor oil in gaseous form into the exhaust is by far the main source of engine oil consumption, detection of sulfur in the exhaust emission is a valuable way to measure engine oil consumption in a dynamic way. In earlier approaches, this is done by converting all sulfur containing chemical components into SO2 by thermal pyrolysis in a high temperature furnace at atmospheric pressure. The so-formed SO2 then is detected by broadband-UV-induced fluorescence or mass spectrometric methods. The challenge is to reach the necessary detection limit of 50 ppb. The new approach presented here includes sulfur conversion in a low-pressure discharge cell and laser-induced fluorescence with wavelength and fluorescence lifetime selection. A limit of detection down to 10 ppb at a temporal resolution in the time scale of few seconds is reached. Extensive, promising studies have been performed at a real engine test bench. Future developments of a compact, mobile device based on these improvements are discussed.

Lubricating Oil Consumption Measurement on Large Gas Engines

“…This method is based on marking synthetic base oil with a non-radioactive isotope of hydrogen: deuterium by a two-step hydrogen/deuterium exchange process. Present in oil/additives by nature Not detectable online [9] Zinc (Zn) Present in oil/additives by nature Adsorption/memory effects [10] Sulfur (S or SO 2 ) Precisely detectable Insufficient lower detection limit and selectivity [11] Pyrene (C 16 H 10 ) Oil-like physicochemical properties Decomposes during combustion [10] Deuterated polyaromatic hydrocarbons Detectable online Cost, low accuracy [12] The product of this reaction will be called "tracer" throughout this publication. This tracer is then blended into the lubricating oil of the engine.…”