Study of Fluorescence Dye for Tracing Lubrication Oil inside Marine Engines

Sammanfattning: Engine lubrication is very important for engine sustainability and efficiency. It becomes even more important when heavier fuel types who contributes to lubrication are changed to alternative fuel without the same lubrication abilities. Because the performance of lubrication systems sometimes can be very hard to study in real time due to hostile environments inside engines, specialized techniques are required to improve in situ measurements. This thesis aims to evaluate different fluorescence dye use in LIF (Laser induced fluorescence) to trace lubricant oil inside marine engines. The application of the findings could lead to a better understanding of lubrication oil distribution and possible lubrication system improvements. To conduct the tracing, the fluorescence dye must have a strong quantum yield, be compatible with temperatures normal for a marine engine liner and perturb the lubricant oils characteristics as little as possible. Seven different dyes were studied over a temperature range normal to marine engine liners using a Nd-YAG laser to determine the quantum yield and resistivity to temperature while solved in lubricant oil. The most promising dye candidate was then used for 2D-imaging by a ICCD camera to further evaluate the tracing possibilities. The lubricant oil itself was also studied to determine its own fluorescence at wavelengths used. The result showed that three dyes from the Pyrromethene family proved to be feasible candidates, they were soluble in the lubricant oil (Energol CL-DX 405) and had sufficient quantum yield over the specified temperature region. The most promising dye was Pyrromethene 650 due to its red shifted fluorescence spectrum that enabled suppression of the lubricant oil’s fluorescence spectrum through spectral filtering.