Reproducing Internal Injector Deposits Found in Heavy-Duty Vehicles with a Novel Injector Rig

<div class="section abstract"><div class="htmlview paragraph">In recent years, deposit formation in fuel systems for heavy-duty engines, using drop-in fuels, have become increasingly common. Drop-in fuels are particularly appealing because they are compatible with existing engines, allowing for higher proportions of alternative fuels to be blended with conventional fuels. However, the precipitation of insoluble substances from drop-in fuels can result in fuel filter clogging and the formation of internal injector deposits, leading to higher fuel consumption and issues with engine drivability. The precise reasons behind the formation of these deposits in the fuel system remain unclear, with factors such as operating conditions, fuel quality, and fuel contamination all suggested as potential contributors.</div><div class="htmlview paragraph">In order to reproduce and study the formation of internal injector deposits, for heavy-duty engines under controlled conditions and to facilitate a more precise comparison to field trials, a novel injector test rig has been developed. This newly constructed, non-firing rig includes the main components of heavy-duty vehicle engines and uses an electric motor to simulate the revolutions per minute of an engine. A tailored run cycle has been developed to enable the continuous monitoring of injector performance during the deposit formation process, as well as to meticulously mimic the actual operations of a real engine.</div><div class="htmlview paragraph">The deposits formed on injectors during the rig tests were analyzed using scanning electron microscopy with energy dispersive X-ray (SEM-EDX), Fourier-transform infrared spectroscopy (FTIR), and pyrolysis connected to gas chromatography-mass spectroscopy (Py GC-MS).</div><div class="htmlview paragraph">This work presents the outcome of the analysis of injector deposits using the test rig, and compares these findings with deposits gathered from field operations. The deposits obtained from the injector test rig were found to be similar in terms of deposit location, composition, and microstructure, with both sets of deposits containing metal carboxylates and derivatives of engine oil additives. These similarities demonstrate that the test rig effectively reproduces the formation of injector deposits observed in real-world conditions.</div></div>