Automotive Experiences

Articles

Real-Time Surfactant-Free Emulsification of Plastic-Derived Diesel Oil: Combustion and Emission Characteristics

Wargiantoro Prabowo , Wira Jazair Yahya , Ahmad Muhsin Ithnin , Dhani Avianto Sugeng , Trisno Anggoro , Frendy Rian Saputro , Erlan Rosyadi

Published
March 31, 2026

Vol. 9 No. 1 (2026)
Pages 140-159

DOI

Open Access
Share

Abstract

Plastic waste pyrolysis has emerged as a promising strategy for converting non-recyclable plastics into plastic-derived diesel oil (PDDO), providing a pathway for both waste valorization and alternative fuel production. However, the direct utilization of PDDO in diesel engines remains constrained by suboptimal combustion behavior and elevated exhaust emissions. While real-time non-surfactant emulsion fuel supply systems (RTES) have been widely investigated for conventional diesel fuels, their application to PDDO has not yet been systematically evaluated in engine operation. This study presents the first implementation of a real-time non-surfactant emulsification system to generate surfactant-free water-in-PDDO emulsions containing 5–15% water by volume. Engine performance and exhaust emissions were experimentally assessed using a 4.5 kW single-cylinder compression-ignition generator at low and high loads. The results indicate that controlled water addition modifies combustion behavior by improving spray atomization and secondary droplet breakup associated with micro-explosion phenomena. Among the tested blends, the 15% water emulsion (EPO15) provided the most balanced performance, improving brake thermal efficiency by 6.48% while reducing NOx emissions by up to 47.06% compared with the baseline fuel. Exhaust gas temperature was consistently reduced, without substantial deterioration in fuel consumption. These findings demonstrate that RTES can enhance the combustion and emission characteristics of PDDO, supporting its potential application in small-scale compression ignition engine systems.

Keywords

Plastic-derived diesel oil; Surfactant-free emulsion; Engine performance; Emissions; Waste-to-energy

References

  1. [1] Global Waste Management Outlook 2024 - Beyond an age of waste: Turning rubbish into a resource. United Nations Environment Programme, 2024. doi: 10.59117/20.500.11822/44939.
  2. [2] K. Houssini, J. Li, and Q. Tan, “Complexities of the global plastics supply chain revealed in a trade-linked material flow analysis,” Communications Earth & Environment, vol. 6, no. 1, p. 257, Apr. 2025, doi: 10.1038/s43247-025-02169-5.
  3. [3] P. M. Forster et al., “Indicators of Global Climate Change 2023: annual update of key indicators of the state of the climate system and human influence,” Earth System Science Data, vol. 16, no. 6, pp. 2625–2658, Jun. 2024, doi: 10.5194/essd-16-2625-2024.
  4. [4] I. U. Eze, O. O. Okwonna, G. W. Komi, A. I. Hart, and I. Vincent-Akpu, “Comparative Analysis of Kerosene Grade Fuel from Pyrolysis of HDPE and LDPE Waste Plastics,” Journal of Engineering Research and Reports, vol. 26, no. 2, pp. 1–13, Jan. 2024, doi: 10.9734/jerr/2024/v26i21068.
  5. [5] M. H. Rahman, P. R. Bhoi, and P. L. Menezes, “Pyrolysis of waste plastics into fuels and chemicals: A review,” Renewable and Sustainable Energy Reviews, vol. 188, p. 113799, Dec. 2023, doi: 10.1016/j.rser.2023.113799.
  6. [6] S. Pal et al., “Experimental evaluation of diesel blends mixed with municipal plastic waste pyrolysis oil on performance and emission characteristics of CI engine,” Case Studies in Thermal Engineering, vol. 47, p. 103074, Jul. 2023, doi: 10.1016/j.csite.2023.103074.
  7. [7] A. Pumpuang, N. Klinkaew, K. Wathakit, A. Sukhom, and E. Sukjit, “The influence of plastic pyrolysis oil on fuel lubricity and diesel engine performance,” RSC Advances, vol. 14, no. 14, pp. 10070–10087, 2024, doi: 10.1039/D3RA08150H.
  8. [8] B. Alawa and S. Chakma, “Experimental Investigation in Compression Ratio on Performance, Combustion and Emission of VCR Engine using Pyrolysis-oil Produced from Waste Plastic Materials,” Materials Today: Proceedings, vol. 72, pp. 2593–2609, 2023, doi: 10.1016/j.matpr.2022.07.228.
  9. [9] P. Singh Gautam, A. Partap Singh, S. Chand, and A. Sehgal, “Combustion knocking intensity behavior analysis using wavelet approach and optimizing water-emulsified diesel fuel: Engine combustion, performance and emission analysis with novel surfactants,” Fuel, vol. 391, no. February, p. 134656, 2025, doi: 10.1016/j.fuel.2025.134656.
  10. [10] A. K. Hasannuddin et al., “Effect of emulsion fuel on engine emissions–A review,” Clean Technologies and Environmental Policy, vol. 18, no. 1, pp. 17–32, Jan. 2016, doi: 10.1007/s10098-015-0986-x.
  11. [11] P. Murugesan et al., “Exploration of low heat rejection engine characteristics powered with carbon nanotubes-added waste plastic pyrolysis oil,” Process Safety and Environmental Protection, vol. 176, pp. 1101–1119, Aug. 2023, doi: 10.1016/j.psep.2023.06.051.
  12. [12] R. Vigneswaran, D. Balasubramanian, and B. D. S. Sastha, “Performance, emission and combustion characteristics of unmodified diesel engine with titanium dioxide (TiO2) nano particle along with water-in-diesel emulsion fuel,” Fuel, vol. 285, p. 119115, Feb. 2021, doi: 10.1016/j.fuel.2020.119115.
  13. [13] M. R. Seifi et al., “Statistical evaluation of the effect of water percentage in water-diesel emulsion on the engine performance and exhaust emission parameters,” Energy, vol. 180, pp. 797–806, Aug. 2019, doi: 10.1016/j.energy.2019.04.093.
  14. [14] S. Gowrishankar and A. Krishnasamy, “Emulsification – A promising approach to improve performance and reduce exhaust emissions of a biodiesel fuelled light-duty diesel engine,” Energy, vol. 263, p. 125782, Jan. 2023, doi: 10.1016/j.energy.2022.125782.
  15. [15] R. P. Singh and P. S. Gautam, “Predictive modeling and multi-objective optimization of CI engine performance, combustion and emissions parameters with water-emulsified diesel using SVR and SHO,” Biomass and Bioenergy, vol. 208, p. 108818, May 2026, doi: 10.1016/j.biombioe.2025.108818.
  16. [16] S. A. A. Kashinath, H. Hashim, N. A. Yunus, and A. A. Mustaffa, “Design of surfactant for water in diesel emulsion fuel for designing eco-friendly fuel,” Chemical Engineering Transactions, vol. 63, pp. 433–438, 2018, doi: 10.3303/CET1863073.
  17. [17] Md Mujibur Rahman, Wira Jazair Yahya, Hasannuddin Abd Kadir, Ahmad Muhsin Ithnin, Qayyum Mohd Tamam, and Hasbullah Abdul Rahman, “Comparison of Diesel Engine Performance between a Mechanical Pump and a Common Rail Fuel Injection System Equipped with Real-Time Non-Surfactant Emulsion Fuel Supply System,” Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, vol. 91, no. 2, pp. 41–50, Feb. 2022, doi: 10.37934/arfmts.91.2.4150.
  18. [18] W. N. I. Wan Mahdi et al., “Effect of Electrical Load On the Emulsification Methods of Inline Mixing System RTES Produced by The Static Mixer and Ultrasonic on Fuel Consumption and Emission Characteristics,” Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, vol. 78, no. 1, pp. 88–99, Dec. 2020, doi: 10.37934/arfmts.78.1.8899.
  19. [19] M. A. Ahmad et al., “Combustion performance and exhaust emissions fuelled with non-surfactant water-in-diesel emulsion fuel made from different water sources,” Environmental Science and Pollution Research, vol. 25, no. 24, pp. 24266–24280, Aug. 2018, doi: 10.1007/s11356-018-2492-2.
  20. [20] A. M. Ithnin et al., “Emulsifier-free Water-in-Diesel emulsion fuel: Its stability behaviour, engine performance and exhaust emission,” Fuel, vol. 215, pp. 454–462, Mar. 2018, doi: 10.1016/j.fuel.2017.11.061.
  21. [21] D. A. Sugeng, A. M. Ithnin, W. J. Yahya, and H. Abd Kadir, “Emulsifier-Free Water-in-Biodiesel Emulsion Fuel via Steam Emulsification: Its Physical Properties, Combustion Performance, and Exhaust Emission,” Energies, vol. 13, no. 20, p. 5406, Oct. 2020, doi: 10.3390/en13205406.
  22. [22] R. T. Omi et al., “Performance and Emissions of Diesel Engine with Circulation Non-Surfactant Emulsion Fuel System,” Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, vol. 82, no. 2, pp. 96–105, May 2021, doi: 10.37934/arfmts.82.2.96105.
  23. [23] W. N. I. W. Mahdi et al., “The effect of different in-line mixers producing emulsifier-free bio-diesel emulsion on the diesel engine combustion performance and exhaust emission,” Fuel, vol. 337, p. 126886, Apr. 2023, doi: 10.1016/j.fuel.2022.126886.
  24. [24] M. Q. Mohd Tamam et al., “Performance and emission studies of a common rail turbocharged diesel electric generator fueled with emulsifier free water/diesel emulsion,” Energy, vol. 268, p. 126704, Apr. 2023, doi: 10.1016/j.energy.2023.126704.
  25. [25] H. Wu, F. Xie, and Y. Han, “Effect of cetane coupled with various engine conditions on diesel engine combustion and emission,” Fuel, vol. 322, p. 124164, Aug. 2022, doi: 10.1016/j.fuel.2022.124164.
  26. [26] R. Kizza, N. Banadda, and J. Seay, “Qualitative and energy recovery potential analysis: plastic-derived fuel oil versus conventional diesel oil,” Clean Technologies and Environmental Policy, vol. 24, no. 3, pp. 789–800, Apr. 2022, doi: 10.1007/s10098-021-02028-9.
  27. [27] F. Faisal, M. G. Rasul, M. I. Jahirul, and A. A. Chowdhury, “Waste plastics pyrolytic oil is a source of diesel fuel: A recent review on diesel engine performance, emissions, and combustion characteristics,” Science of The Total Environment, vol. 886, p. 163756, Aug. 2023, doi: 10.1016/j.scitotenv.2023.163756.
  28. [28] M. Sekar, T. R. Praveenkumar, V. Dhinakaran, P. Gunasekar, and A. Pugazhendhi, “Combustion and emission characteristics of diesel engine fueled with nanocatalyst and pyrolysis oil produced from the solid plastic waste using screw reactor,” Journal of Cleaner Production, vol. 318, p. 128551, 2021, doi: 10.1016/j.jclepro.2021.128551.
  29. [29] F. Faisal, M. G. Rasul, A. A. Chowdhury, M. I. Jahirul, and M. A. Hazrat, “Performance and emission characteristics of a CI engine with post-treated plastic pyrolysis oil and diesel blend,” Energy Reports, vol. 9, pp. 87–92, Nov. 2023, doi: 10.1016/j.egyr.2023.09.142.
  30. [30] A. G. M. B. Mustayen, M. G. Rasul, X. Wang, M. A. Hazrat, M. Negnevitsky, and M. I. Jahirul, “Impact of waste-plastic-derived diesel on the performance and emission characteristics of a diesel engine under low load conditions,” Energy Conversion and Management, vol. 283, p. 116936, May 2023, doi: 10.1016/j.enconman.2023.116936.
  31. [31] C. P. Onuoha, I. N. Etim, and E. E. Oguzie, “Impact of water‐in‐diesel emulsion on compression ignition engine’s emissions and its challenges—A detailed review,” Vietnam Journal of Chemistry, vol. 62, no. 4, pp. 421–436, Aug. 2024, doi: 10.1002/vjch.202300368.
  32. [32] M. Q. Mohd Tamam et al., “Engine performance and emissions evaluation of surfactant-free B30 biodiesel–diesel/water emulsion as alternative fuel,” Scientific Reports, vol. 13, no. 1, p. 10599, Jun. 2023, doi: 10.1038/s41598-023-37662-4.
  33. [33] P. K. Mondal and B. K. Mandal, “A comprehensive review on the feasibility of using water emulsified diesel as a CI engine fuel,” Fuel, vol. 237, pp. 937–960, Feb. 2019, doi: 10.1016/j.fuel.2018.10.076.
  34. [34] A. Wiangkham, N. Klinkaew, P. Aengchuan, P. Liplap, A. Ariyarit, and E. Sukjit, “Experimental and optimization study on the effects of diethyl ether addition to waste plastic oil on diesel engine characteristics,” RSC Advances, vol. 13, no. 36, pp. 25464–25482, 2023, doi: 10.1039/D3RA04489K.
  35. [35] D. Saha and B. Roy, “Influence of areca nut husk nano-additive on combustion, performance, and emission characteristics of compression ignition engine fuelled with plastic-grocery-bag derived oil-water-diesel emulsion,” Energy, vol. 268, p. 126682, Apr. 2023, doi: 10.1016/j.energy.2023.126682.
  36. [36] B. K. Debnath, U. K. Saha, and N. Sahoo, “A comprehensive review on the application of emulsions as an alternative fuel for diesel engines,” Renewable and Sustainable Energy Reviews, vol. 42, pp. 196–211, Feb. 2015, doi: 10.1016/j.rser.2014.10.023.
  37. [37] M. D. Anil, V. B. Hemadri, and M. Swamy, “Experimental investigation on impact of water in diesel emulsion in a single-cylinder research diesel engine,” International Journal of Ambient Energy, vol. 44, no. 1, pp. 399–412, Dec. 2023, doi: 10.1080/01430750.2022.2128411.
  38. [38] Y. M. Oo, J. Thawornprasert, N. Intaprom, K. Rodniem, and K. Somnuk, “Diesel–Biodiesel–Water Fuel Nanoemulsions for Direct Injection and Indirect Injection Diesel Engines: Performance and Emission Characteristics,” ACS Omega, vol. 7, no. 39, pp. 34951–34965, Oct. 2022, doi: 10.1021/acsomega.2c03553.
  39. [39] A. Ali, A. R. A. Aziz, M. A. Ismael, and S. Alqaed, “Biosurfactants as an alternative eco-friendly solution for water-in-diesel emulsions-A review paper,” Heliyon, vol. 10, no. 17, p. e37485, Sep. 2024, doi: 10.1016/j.heliyon.2024.e37485.
  40. [40] S. Vellaiyan and K. S. Amirthagadeswaran, “The role of water-in-diesel emulsion and its additives on diesel engine performance and emission levels: A retrospective review,” Alexandria Engineering Journal, vol. 55, no. 3, pp. 2463–2472, Sep. 2016, doi: 10.1016/j.aej.2016.07.021.
  41. [41] V. L. Mangesh, S. Padmanabhan, P. Tamizhdurai, and A. Ramesh, “Experimental investigation to identify the type of waste plastic pyrolysis oil suitable for conversion to diesel engine fuel,” Journal of Cleaner Production, vol. 246, p. 119066, 2020, doi: 10.1016/j.jclepro.2019.119066.
  42. [42] G. Soundararajan, B. Chidambaranathan, A. K. Rajendran, D. Venugopal, and Y. Devarajan, “Plastic pyrolytic oils as renewable fuel: improving its physical properties and ignition patterns by waste renewable source—an experimental analysis,” Environmental Science and Pollution Research, vol. 31, no. 18, pp. 26497–26509, Mar. 2024, doi: 10.1007/s11356-024-32668-5.
  43. [43] Z. Yang et al., “Characterization of renewable diesel, petroleum diesel and renewable diesel/biodiesel/petroleum diesel blends,” Renewable Energy, vol. 224, p. 120151, Apr. 2024, doi: 10.1016/j.renene.2024.120151.
  44. [44] D. S. Devi, R. Kumar, and U. Rajak, “Experimental investigation of performance, emission and combustion characteristics of a CI engine fuelled by blends of waste plastic oil with diesel,” Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, vol. 44, no. 3, pp. 7693–7708, Sep. 2022, doi: 10.1080/15567036.2022.2115582.
  45. [45] N. Karisathan Sundararajan and A. R. B. Ammal, “Improvement studies on emission and combustion characteristics of DICI engine fuelled with colloidal emulsion of diesel distillate of plastic oil, TiO2 nanoparticles and water,” Environmental Science and Pollution Research, vol. 25, no. 12, pp. 11595–11613, Apr. 2018, doi: 10.1007/s11356-018-1380-0.
  46. [46] F. R. Saputro et al., “Effects of oxyhydrogen enrichment on diesel engine performance and emissions using B35 and its water-in-biodiesel emulsion,” International Journal of Hydrogen Energy, vol. 142, pp. 109–121, Jun. 2025, doi: 10.1016/j.ijhydene.2025.05.359.
  47. [47] J. Park and J. Oh, “Study on the characteristics of performance, combustion, and emissions for a diesel water emulsion fuel on a combustion visualization engine and a commercial diesel engine,” Fuel, vol. 311, p. 122520, Mar. 2022, doi: 10.1016/j.fuel.2021.122520.
  48. [48] C. Liu et al., “A model for evaluating the micro-explosion of a single droplet of water-in-oil emulsions and the effect of hydrophilic surfactants on the phenomenon,” Chemical Engineering Science, vol. 262, p. 118047, Nov. 2022, doi: 10.1016/j.ces.2022.118047.
  49. [49] S. Ren, Z. Wang, B. Li, H. Liu, and J. Wang, “Development of a reduced polyoxymethylene dimethyl ethers (PODEn) mechanism for engine applications,” Fuel, vol. 238, pp. 208–224, Feb. 2019, doi: 10.1016/j.fuel.2018.10.111.
  50. [50] N. Kumar, H. S. Pali, and S. Bansal, “Some Studies on NOX Reduction From a Diesel Engine Using Stabilized Emulsion,” in ASME 2018 International Mechanical Engineering Congress and Exposition, American Society of Mechanical Engineers, Nov. 2018. doi: 10.1115/IMECE2018-87374.
  51. [51] H. Yang, S. R. Krishnan, K. K. Srinivasan, and K. C. Midkiff, “Modeling of NOx Emissions Using a Super-Extended Zel’dovich Mechanism,” in Design and Control of Diesel and Natural Gas Engines for Industrial and Rail Transportation Applications, ASMEDC, Jan. 2003, pp. 121–128. doi: 10.1115/ICEF2003-0713.
  52. [52] M. Q. M. Tamam et al., “Application of an Inline Mixer to Produce Surfactant-Free Biodiesel-diesel/Water Emulsion Fuel: An Analysis of Water Droplets Characteristics and Drive Cycle Emissions,” Arabian Journal for Science and Engineering, vol. 50, no. 12, pp. 9261–9274, Jun. 2025, doi: 10.1007/s13369-024-09408-5.
  53. [53] I. Kalargaris, G. Tian, and S. Gu, “Experimental evaluation of a diesel engine fuelled by pyrolysis oils produced from low-density polyethylene and ethylene–vinyl acetate plastics,” Fuel Processing Technology, vol. 161, pp. 125–131, Jun. 2017, doi: 10.1016/j.fuproc.2017.03.014.
  54. [54] Y. Yan, T. Shang, L. Li, R. Yang, Z. Liu, and J. Liu, “Numerical Investigation of In-Cylinder Combustion Behaviors in a Medium-Speed Diesel Engine,” Journal of Energy Resources Technology, vol. 146, no. 8, Aug. 2024, doi: 10.1115/1.4065289.
  55. [55] A. N. Dibofori-Orji, “Critical processes involved in formulation of water-in-oil fuel emulsions, combustion efficiency of the emulsified fuels and their possible environmental impacts,” Research Journal of Applied Sciences, Engineering and Technology, vol. 3, no. 8, pp. 701–706, 2011.
  56. [56] K. Kusmiyati and A. Fudholi, “A systematic literature review on the pyrolysis of plastic waste and waste oil for fuel production: Targeted waste management solution for central Java, Indonesia,” Cleaner Waste Systems, vol. 11, p. 100308, Jun. 2025, doi: 10.1016/j.clwas.2025.100308.
  57. [57] G. A. Bin Mukhtar, T. Nagata, J. Hayashi, N. Horibe, H. Kawanabe, and M. Fuchihata, “Analysis of emission and combustion behaviors of water-emulsified diesel with various water contents and droplet diameters,” Journal of Thermal Science and Technology, vol. 20, no. 1, pp. 24–00385, 2025, doi: 10.1299/jtst.24-00385.
  58. [58] H. Watanabe, Y. Suzuki, T. Harada, Y. Matsushita, H. Aoki, and T. Miura, “An experimental investigation of the breakup characteristics of secondary atomization of emulsified fuel droplet,” Energy, vol. 35, no. 2, pp. 806–813, Feb. 2010, doi: 10.1016/j.energy.2009.08.021.
  59. [59] Y. Han, Z. Tian, J. Xu, Q. Liang, Z. Dai, and F. Wang, “A new experimental method for studying the single droplet breakup mode of diesel-water composite droplet fuel,” Petroleum Science and Technology, vol. 43, no. 12, pp. 1275–1292, Jun. 2025, doi: 10.1080/10916466.2024.2325602.
  60. [60] M. Yahaya Khan, Z. A. Abdul Karim, F. Y. Hagos, A. R. A. Aziz, and I. M. Tan, “Current Trends in Water-in-Diesel Emulsion as a Fuel,” The Scientific World Journal, vol. 2014, pp. 1–15, 2014, doi: 10.1155/2014/527472.
  61. [61] P. S. Kumar and G. Sankaranarayanan, “Investigation on environmental factors of waste plastics into oil and its emulsion to control the emission in DI diesel engine,” Ecotoxicology and Environmental Safety, vol. 134, pp. 440–444, Dec. 2016, doi: 10.1016/j.ecoenv.2016.01.021.
  62. [62] N. C. Belay, B. A. Fentaw, R. B. Nallamothu, and M. S. Kebede, “Performance evaluation of liquid fuel derived from waste plastics for diesel engine applications and emissions characteristics,” Energy, vol. 318, p. 134911, Mar. 2025, doi: 10.1016/j.energy.2025.134911.
  63. [63] P. B. Senthilkumar, M. Parthasarathy, R. Nagarajan, N. Murgunachiappan, P. V. Elumalai, and B. H. Varaprasad, “The effect of thermal degradation and thermogravimetric analysis on pyrolysis oil production from waste milk packet for CI engine application,” Journal of Thermal Analysis and Calorimetry, vol. 147, no. 17, pp. 9677–9691, Sep. 2022, doi: 10.1007/s10973-022-11226-6.
Article Metrics
51
Views
40
Downloads

SCITE

DIMENSIONS

Publication Information
Published March 31, 2026
Section Articles
Copyright Copyright (c) 2026 Wargiantoro Prabowo, Wira Jazair Yahya, Ahmad Muhsin Ithnin, Dhani Avianto Sugeng, Trisno Anggoro, Frendy Rian Saputro, Erlan Rosyadi
Keywords
  • Plastic-derived diesel oil
  • Surfactant-free emulsion
  • Engine performance
  • Emissions
  • Waste-to-energy