Continuous Oil Consumption Measurement Using Laser Induced Breakdown Spectroscopy

This paper describes a new method for measuring oil consumption using laser induced breakdown spectroscopy (LIBS). LIBS focuses a high energy laser pulse on a sample to form a transient plasma. As the plasma cools, each element produces atomic emission lines which can be used to identify and quantify the elements present in the original sample. In this work, a LIBS system was used on simulated engine exhaust with a focus on quantifying the inorganic components (termed ash) of the particulate emissions. Because some of the metallic elements in the ash almost exclusively result from lube oil consumption, their concentrations can also be correlated to an oil consumption rate. Initial testing was performed using SwRI’s Exhaust Composition Transient Operation Laboratory®(ECTO-Lab®) burner system so that oil consumption and ash mass could be precisely controlled. Several spectral regions were identified where absorptions attributable to calcium exhibited a response in proportion to the amount of lube oil introduced into the burner. This allowed for quantitative calibration of the LIBS instrument and suggests that unknown oil consumption amounts could be determined in future applications of this technology.