A Measurement of Fuel Filters’ Ability to Remove Soft Particles, with a Custom-Built Fuel Filter Rig

Biofuel can enable a sustainable transport solution and lower greenhouse gas emissions compared to standard fuels. This study focuses on biodiesel, implemented in the easiest way as drop in fuel. When mixing biodiesel into diesel one can run into problems with solubility causing contaminants precipitating out as insolubilities. These insolubilities, also called soft particles, can cause problems such as internal injector deposits and nozzle fouling. One way to overcome the problem of soft particles is by filtration. It is thus of great interest to be able to quantify fuel filters’ ability to intercept soft particles. The aim of this study is to test different fuel filters for heavy-duty engines and their ability to filter out synthetic soft particles. A custom-built fuel filter rig is presented, together with some of its general design requirements. For evaluation of the efficiency of the filters, fuel samples were taken before and after the filters. The fuel samples were analyzed with gas chromatography-mass spectrometry (GC-MS) and x-ray fluorescence spectroscopy (XRF) to estimate the soft particle removal efficiency of each fuel filter. Furthermore, the pressure drop across the filters was measured, to provide an indication about their plugging potential. Results are presented about the concentration dependency of synthetic soft particles, both regarding pressure drop and efficiency of removal. Finally, different fuel filter materials were compared regarding their efficiency to remove soft particles. The results of this paper show the basic concepts of how soft particles can be examined in a laboratory scale fuel filter rig, and show a first estimate about the capabilities of soft particle removal by currently available fuel filters.