Reaction of Sulfuric Acid in Lube Oil: Implications for Large Two-Stroke Diesel Engines

Kasper Hartvig Lejre, Søren Kiil, Peter Glarborg, Henrik Christensen, Stefan Mayer

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Slow-steaming operation and an increased pressure in the combustion chamber have contributed to increased sulfuric acid (H2SO4) condensation on the cylinder liners in large two-stroke marine diesel engines, thus causing increased corrosion wear. To cope with this, lube oils are formulated with overbased detergent additives present as CaCO3 reverse micelles to neutralize the condensing H2SO4. In this present work, a mixed flow reactor (MFR) setup aims to investigate the neutralization reaction by varying Ca/S molar ratio, stirrer speed, H2SO4 inlet concentration, and residence time. Lube oil samples from the outlet of the MFR were analysed by use of Fourier Transform Infrared Spectroscopy (FTIR) and a titration method. The MFR results indicate that the CaCO3-H2SO4 reaction is very fast in a real engine, if the cylinder liner is well-wetted, the oil-film is well-mixed, and contains excess of CaCO3 compared to the condensed H2SO4. The observed corrosion wear in large two-stroke marine diesel engines could consequently be attributed to local molar excess of H2SO4 compared to CaCO3 reverse micelles on the cylinder liners.
Original languageEnglish
Title of host publicationProceedings of the ASME 2017 Internal Combustion Engine Division Fall Technical Conference
Number of pages10
VolumeVolume 1: Large Bore Engines; Fuels; Advanced Combustion
PublisherAmerican Society of Mechanical Engineers
Publication date2017
Article numberICEF2017-3580
ISBN (Electronic)978-0-7918-5831-8
Publication statusPublished - 2017
EventInternal Combustion Engine Fall Technical Conference (ICEF 2017) - Seattle, United States
Duration: 15 Oct 201718 Oct 2017


ConferenceInternal Combustion Engine Fall Technical Conference (ICEF 2017)
Country/TerritoryUnited States


  • Corrosion
  • Lubrication
  • Neutralization
  • Mechanism


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