On-Board Ultrasonic Water-in-Diesel Emulsion (WiDE) Fuel System for Low-Emission Diesel Engine Combustion

Kotaro Kojima, Jun Kojima


Water-in-diesel emulsion (WiDE) fuel is a promising alternative fuel capable of reducing nitrogen oxides (NOX) and particulate matter (PM) in diesel engine exhaust while simultaneously preserving combustion efficiency of the engine. However, the instability of WiDE fuel—and the high costs of production and transportation—hinder its commercialization and widespread use. An on-board ultrasonic WiDE fuel supply system is proposed as a solution to this challenge. This system allows diesel fuel and water to be continuously emulsified on-board a diesel vehicle. Diesel fuel and water, stored in individual reservoirs, are conveyed in specific ratios to an in-line mixing chamber and are rapidly homogenized by ultrasonic cavitation before entering the fuel injectors. The produced emulsion fuel is then supplied to the engine. A proof-of-concept study was conducted to compare exhaust emissions between emulsion fuels and conventional fuels. Open-flame combustion experiments were conducted using a lab-scale burner to test the system with both diesel and biodiesel fuels. Unique optical diagnostics and image-processing techniques were used to estimate PM emission levels. Results showed a reduction of PM with the use of the on-board WiDE system compared to traditional diesel fuels. PM emissions from biodiesel fuel were reduced by 58% when water-in-biodiesel emulsion was combusted with 2% water. Additionally, a PM emission reduction of 35% was achieved through emulsification of diesel fuel with 2% water. This prototype demonstrates the potential for the on-board WiDE fuel supply concept to both overcome the traditional barriers hindering the commercialization of WiDE fuel and preserve its low-emission and superior combustion efficiency characteristics.


diesel engine; combustion; exhaust emissions; water-fuel emulsion; ultrasonic cavitation; optical diagnostics

Full Text:


DOI: http://dx.doi.org/10.18061/ojs.v118i2.6443


  • There are currently no refbacks.

Copyright (c) 2018 Kotaro Kojima, Jun Kojima

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.



Visit The Ohio Academy of Science's webpage

Visit our Knowledge Bank site for articles published from 1900 through 2013.

The Ohio Journal of Science is published by The Ohio State University Libraries in partnership with The Ohio Academy of Science.

If you encounter problems with the site or have comments to offer, including any access difficulty due to incompatibility with adaptive technology, please contact libkbhelp@lists.osu.edu.

ISSN: 2471-9390 (Online); 0030-0950 (Print)