Comparative Study of Diesel Engine Performance and Emissions Using Emulsifier-Based and Emulsifier-Free Water-in-Plastic Diesel Oil Emulsions
Wargiantoro Prabowo- Wira Jazair Yahya- Ahmad Muhsin Ithnin- Dhani Avianto Sugeng- Trisno Anggoro- Frendy Rian Saputro- Tyas

1) Advanced Vehicle System, Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100 Kuala Lumpur, Malaysia.
2) Research Center for Energy Conversion and Conservation, National Research and Innovation Agency, 625 Building, KST BJ Habibie, South Tangerang, 15314, Indonesia.
3) Institute for Sustainable Transport HICoE, Universiti Teknologi Malaysia, Jalan Lengkok Kuasa, Johor Bahru, Malaysia.

Abstract

The conversion of municipal plastic waste (MWP) into alternative fuels through pyrolysis presents a promising approach to mitigate environmental pollution and reduce fossil fuel dependency. This study examines the performance and emissions of emulsified plastic diesel oil (PDO) produced using two methods: an emulsifier-based PDO (EEPO) formulation containing 2% SPAN-80 and TWEEN-80, and an emulsifier-free PDO (EPO) approach using a Real-Time Non-Surfactant Emulsion Fuel Supply System (RTES) device. Both fuels incorporate 5% water by volume. Engine tests on a single-cylinder diesel engine at loads ranging from 0 to 4 kW were conducted to evaluate thermal efficiency (TE), exhaust gas temperature (EGT), and emissions of CO, CO&#8322-, and NOx. Compared to pure PDO, EPO and EEPO increased TE by 2.11% and 1.78%, reduced EGT by 0.88% and 0.71%, raised CO&#8322- emissions by 4.49% and 6.15%, and lowered NOx by 9.98% and 8.90%, respectively. These improvements are attributed to the micro-explosion phenomenon triggered by water droplets in PDO fuel, which enhances combustion efficiency and emission behavior. The findings suggest that while both emulsified fuels offer comparable performance benefits, the RTES-based EPO presents a simpler, surfactant-free alternative for the sustainable utilization of PDO fuel.

Keywords: Plastic diesel oil, emulsifier-based, emulsifier-free, performance, emission.

Topic: Water, Food, Energy Nexus