On the origins of lubricity and surface cleanliness in ethanol-diesel fuel blends

Frank T. Hong, Eshan Singh, Mani Sarathy

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Ethanol is the most used bio-derived fuel additive. However, adding ethanol in diesel fuel may negatively impact lubricity or surface cleanliness, which is critical for high-pressure fuel injection systems employed in compression ignition engines. This work investigates surfaces lubricated by ethanol–diesel blends. Adding 5 wt% ethanol in diesel showed negligible changes in fuel lubricity, while blending 10, 20, and 40 wt% ethanol increased wear rates by 46, 81, and 239% respectively. These increases in wear rates (with increases in ethanol by wt%) correlate with the evolution of electrical contact resistance (ECR) values over time. As more ethanol was added, the ECR values signaled thinner fuel films, more metal-to-metal contacts, and a delayed onset of frictional product growth. Raman spectra showed that forming frictional species produced by tribochemical reactions enhanced fuel lubricity. The absence of some frictional species in ethanol lubricated surfaces points to simultaneously improved surface cleanliness and reduced lubricity.
Original languageEnglish (US)
Pages (from-to)121135
StatePublished - Jun 4 2021

Bibliographical note

KAUST Repository Item: Exported on 2021-06-07
Acknowledgements: The authors would like to acknowledge the fund allocated to this research by Saudi Aramco and King Abdullah University of Science and Technology (KAUST).

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Organic Chemistry
  • General Chemical Engineering
  • Fuel Technology


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