Moisture Content Assessment of Commercially Available Diesel Fuel Using Impedance Spectroscopy

Diesel is consistently a very popular fuel for internal combustion engines. Its consumption in the European Union has been rising over recent years, as has the number of engines increasingly sensitive to fuel contamination. One of the most important parameters affecting diesel quality is water content. Its exceedance of the standard’s permissible amount carries the risk of serious damage to expensive, modern fuel injection systems. Current methods of measuring water content require both specialised personnel and equipment, as well as transporting the sample to a suitable laboratory. Analysing the properties of diesel is challenging, mainly because many types of the fuel are sold, the chemical composition of which is always a well-guarded manufacturer’s secret. The research presented in this paper is aimed at verifying whether it is possible to test the moisture content of diesel using impedance spectroscopy. To date, it is the first such attempt with commercially available diesel using this method, which, once refined, could be used in situ. The authors propose and apply a novel technique that is able to be used when the electrical properties of tested oils are unknown. The experimental results obtained show that it is possible to use impedance spectroscopy to estimate the water content of different types of diesel fuel. The measurement accuracy achieved makes it possible to detect approaching or exceeding the permissible water content.