Study of the stability of water-fuel emulsion for diesel engine

It is known that water-fuel emulsions used in diesel engines have a number of advantages over traditional diesel fuels, which significantly affects the efficiency and environmental performance of the engines. The use of water-fuel emulsions can be associated with several problems related to their stability, such as phase separation, coalescence, and sedimentation, as well as the quality of the components and others. These issues encourage researchers to thoroughly study the properties of water-fuel emulsions and improve methods for their production. This paper presents the results of a study of the stability of water-fuel emulsions using photon correlation spectroscopy and the kinetics of changes in T₂ NMR relaxation times during the sedimentation of emulsion water droplets using the example of a Euro C diesel fuel + water system. It is shown that over time, a transition from a unimodal distribution of water droplet hydrodynamic radii to a bimodal distribution can be observed. This is explained by a sharp increase in droplet aggregation and the weakening of this process by the emulsifier, the concentration of which decreases in the beam scattering region. NMR T₂ relaxation times measured using Niumag NMR Data Analysis Software V1.1 (Pore Size Distribution) made it possible to determine the size distribution of water droplets in the emulsion using an alternative method. A longer emulsion separation process was found in samples with a longer emulsification time. An emulsion obtained without an emulsifier is very unstable due to strong coalescence and quickly separates. Prolonged whisking is essential for obtaining a stable, finely dispersed emulsion. The optimal emulsifier amount is no more than 1%. The results obtained in this study can be useful for dispersion analysis of any organic emulsions containing microscopic droplets of immiscible liquid.

1. Rheological properties of water-fuel emulsions prepared by injecting water into diesel fuel / L. S. Keruchenko, E. I. Maltseva, S. P. Prokopov, A. S. Soyunov. – DOI: 10.48136/2222-0364_2022_1_129 // Bulletin of Omsk State Agrarian University. – 2022. – № 1 (45). – P. 129–138.

2. Patrov, F. V. Use of water-fuel emulsion in the operation of marine internal combustion engines / F. V. Patrov, O. S. Vakhromeev // Bulletin of the Astrakhan State Technical University. Series: Marine Engineering and Technology. – 2009. – № 1. – P. 223–225.

3. Attia, A. M. A. Features of the preparation of water-fuel emulsions based on light fuels / A. M. A. Attia // Fundamental research. – 2011. – № 8. – P. 706–709.

4. Dorokhov, A. F. Control of flammability of water-fuel emulsion by regulation of moisture content / A. F. Dorokhov, F. V. Patrov, V. V. Kabylbekova // Bulletin of Astrakhan State Technical University. Series: Marine Engineering and Technology. – 2014. – № 2. – P. 67–73.

5. Gopidesi, R. K. A review on emulsified fuels and their application in diesel engine / R. K. Gopidesi, P. S. Rajaram. – DOI: 10.1080/01430750.2019.1667435 // International Journal of Ambient Energy. – 2019. – P. 9.

6. Biplab, K. Debnath. A comprehensive review on the application of emulsions as an alternative fuel for diesel engines / K. Debnath Biplab, K. Saha Ujjwal, Sahoo Niranjan // Renewable and Sustainable Energy Reviews. – 2015. – № 42. – P. 196 – 211.

7. Fuel properties of water emulsion fuel prepared using porous membrane method for low pollutant engine at various temperatures / W. Seungchul, K. Woongil, L. Jungkoo, L. Kihyung // Energy Reports. – 2021. – № 7. – P. 6638–6650.

8. The characteristic of spray using diesel water emulsified fuel in a diesel engine / P. Sangki, W. Seungchul, K. Hyungik, L. Kihyung // Applied Energy. – 2016. – № 176. – P. 209–220.

9. Osama, A. E. Experimental Investigation on a Diesel Engine Fueled by DieselBiodiesel Blends and their Emulsions at Various Engine Operating Conditions / A. E. Osama, M. R. Murari, S. S. Manpreet // Applied Energy. – 2017. – № 203. – P. 582–593.

10. Investigation into the influence of droplet size on the stability of diesel emulsions based on multiple light scattering / Liu Jincheng, Dai Shiqi, Bao Xicheng [et al.] // Journal of Molecular Liquids. – 2023. – Vol. 390 B. – Art. 123182.

11. Current trends in water-in-diesel emulsion as a fuel. / M. Y. Khan, Z. A. A. Karim, F. Y. Hagos [et al.]. – DOI: 10.1155/2014/527472 // ScientificWorld Journal. – 2014. – № 1. – P. 1–15. – URL: https://pmc.ncbi.nlm.nih.gov/articles/PMC3916022 (date of treatment: 25.03.2026)

12. Diesel engine fuel consumption and emission analysis using steam generated non-surfactant water-in-diesel emulsion fuel / D. A. Sugeng, M. F. H. M. Zahari, A. M. Ithnin [et al.]. – DOI: 10.1088/1757-899X/257/1/012036 // Conference Series Materials Science and Engineering. – 2017. – Vol. 257, № 1. – P. 012036.

13. Water-in-diesel fuel nanoemulsions: Preparation, stability and physical properties / M. R. Noor El-Din, S. H. El-Hamouly, H. M. Mohamed [et al.]. – DOI: 10.1088/1757-899X/257/1/012036 // Egyptian Journal of Petroleum. – 2013. – Vol. 22, № 4. – P. 517–530.

14. Kirichenko, M. N. Appearance of an artifact peak in the particle size distribution measured by the DLS method at low concentrations / M. N. Kirichenko, A. T. Sanoeva, L. L. Chaikov // Brief communications on physics of the Lebedev Physical Institute. – 2016. – № 8. – P. 32–38.

15. Study of marine motor oils by dynamic light scattering method / N. Ya. Sinyavsky, I. P. Korneva, A. M. Ivanov, N. A. Kostrikova. – DOI: 10.37220/MIT.2020.50.4.014 // Marine intelligent technologies. – 2020. – № 4 (50), part 1. – P. 103–108.

16. Sinyavsky, N. NMR relaxometry study of demulsification of diesel fuel / N. Sinyavsky, O. Synashenko, N. Kostrikova . – DOI: 10.1007/s00723-025-01820-w // Applied Magnetic Resonance. – 2026. – № 57.