Vol.9 (2019) No. 1 ISSN: 2088-5334 Experimental Analysis on the Ultrasound-based Mixing Technique Applied to Ultra-low Sulphur Diesel and Bio-oils Anh Tuan Hoang #,* , Viet Dung Tran + # Ho Chi Minh City University of Transport, Ho Chi Minh City, Vietnam Email:: anhtuanhoang1980@gmail.com * Ho Chi Minh City University of Technology (HUTECH), Ho Chi Minh City, Vietnam + The Maritime College I, Haiphong, Vietnam Abstract— Pollution in the maritime field is considered as such a serious problem that scientists, policymakers, and managers are always urged with a desire to find solutions and strategies one way or another to minimize its negative impacts on the environment and the life. Among the effective solutions, the use of fuels with limited-sulfur content or bio-based fuels has been paid much attention to due to their advantages in the use of marine diesel engines. In the current study, a type of fossil diesel fuel with ultra-low sulfur content (ULSD) was mixed with coconut oil (CO) through the ultrasonic treatment under the changes in volume fraction of as-used fuels, the correlation on viscosity selected the rate mixing between ULSD and coconut oil. After 12 minutes of ultrasound treatment, the highest stability of the ULSD-CO emulsion was achieved correspondingly to 97.8% for a mixing rate of 76%(ULSD):24%(CO) along with the distance of 85mm from the containing-vessel bottom to the ultrasound horn tip. Moreover, the spray characteristics including penetration length and a cone angle of ULSD, CO, and ULSD-CO emulsion were also examined and compared to diesel fuel. The similarity of spray characteristics to diesel fuel, containing ultra-low sulfur content and oxygen content, renewability are considered as some advantages of ULSD-CO emulsion as used for diesel engines aiming to meet the stricter requirements of IMO regulations about the strategies of environmental protection. Keywords—ULSD; coconut oil; ultrasonic treatment; spray characteristics; physical properties. I. INTRODUCTION The environment is being seriously polluted due to several various sources, but the main cause resulting in the pollution mentioned above is due to transportation sectors. Facts have shown that the numbers of transportation sectors were increased sharply in contrast to the depletion of fossil fuels [1], [2]. Because of these reasons, two strategies such as finding the renewable energy sources [3] and technical solutions for emission management for the improvement of the effectiveness in the use of energy and the environmental protection are essential [4]. Among emissions emitted into the air from the fossil fuel combustion of diesel engines, sulfur emission (SOx) is a dangerous pollutant and it is complicated to control [5], [6]. In the exhaust line of engines, SOx reacts to water under the appropriate conditions to form sulphuric acid, resulting in negative impacts on materials (corrosion) and environment (acid rain). Therefore, by this way or another, the minimization and limitation of sulfur emissions are compulsory for engine manufacturers, policy- makers, and managers responding to the strict requirements concerning emission management. International shipping is being criticized for contributing 5-10% of global SOx emissions. The reduction of SOx emissions from ships is a hot topic debated in the meeting of the Environmental Protection Committee (MEPC) of the World Maritime Organization (IMO). The MARPOL 73/78 was adopted by the Protocol to control air pollution from ships, the Annex VI of the International Convention for the Prevention of Pollution from Ships, including article 14 of MARPOL Annex VI regulations on reducing emissions of SOx and PM, gases harmful to the environment and human health. The regulation on sulfur content in fuel drops to 0.0015% when the vessel operates in the SOx emission control area (SECA) effective January 1, 2015 [7]. Most notably, the regulation on maximum sulfur content in fuel is 0.05% applied worldwide from January 1, 2020. There are many suggested solution to reduce SOx emissions in maritime such as the injection process management, improvement of the fuel supply system, using low sulfur fuels [8], [9]. However, low sulfur fuel use may be appropriate to existing diesel engines. 307