Analysis of Internal Common Rail Injector Deposits via Thermodesorption Photon Ionization Time of Flight Mass Spectrometry

Increasing reports about malfunctions in common rail injector (CRI) systems lead to a more intensive research on diesel fuel injection systems, which are working under higher pressures and temperatures. Under these conditions, deposits were formed and deteriorated the injector performance. Therefore, it is necessary to investigate the formed deposits to avoid injector sticking. Previous studies have identified different substance classes, such as alkanes, carboxylic salts, and aromatic hydrocarbons in the deposits. In particular, aromatics and polycyclic aromatic hydrocarbons (PAHs) are suspected to produce insoluble solid precipitates. In this study, thermodesorption resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI–ToF–MS) as a novel analytical technique for direct measurements of aromatic-containing deposits on injector parts was performed. Experiments were carried out in a self-made test bench, where the CRI were installed. The influence of the temperature, injection pr...