INFLUENCE OF HARMFUL IMPURITIES IN FUEL ON THE EFFICIENCY OF INTERNAL COMBUSTION ENGINE OPERATION

Abstract

The paper analyses how harmful impurities in motor fuels affect the efficiency, durability and emission performance of modern gasoline and diesel internal combustion engines, with emphasis on high-pressure injection systems such as Common Rail and gasoline direct injection (GDI). Fuel-quality constraints aligned with Euro-5/6 and the Ukrainian standards DSTU 7687:2015 (gasoline) and DSTU 7688:2015 (diesel fuel) are considered. The most relevant contaminants arising during fuel production, transportation, storage and on-vehicle operation are systematized: sulfur-containing compounds, water, mechanical particles/ash, resinous substances and unstable fractions, polycyclic aromatic hydrocarbons, heavy hydrocarbon fractions and biological contamination. It is shown that impurities act in a coupled and cumulative way, altering physicochemical properties of the fuel and disturbing key in-cylinder processes (mixture formation, combustion stability, heat transfer and gas exchange). As a result, injector spray quality deteriorates, deposits and carbon build-up intensify, corrosion and abrasive wear of fuel-system components and the cylinder–piston group accelerate, and aftertreatment efficiency decreases. Typical operational outcomes are illustrated by fuel-filter clogging, injector deposit formation, intensive deposits in the combustion chamber and catalyst fouling, which collectively lead to power loss, higher specific fuel consumption and increased toxic emissions. The need for rapid on-site fuel quality assessment and further development of express monitoring methods suitable for operational conditions is substantiated. Regulatory limit values for sulfur and water, mechanical impurities, aromatics and stability are summarized to support interpretation of mechanisms.