Views: 0 Author: Site Editor Publish Time: 2026-07-16 Origin: Site
Application of Ultrasonic Technology in Diesel EmulsificationDiesel EmulsificationEmulsification
Faced with the dual pressures of global energy shortage and environmental pollution, finding efficient and clean fuel alternatives has become the focus of attention in various countries. Diesel is an important fuel widely used in transportation, industrial boilers, power generation and other fields. Its combustion efficiency and emission levels are directly related to energy consumption and air quality.
Diesel emulsification technology came into being - mixing water into diesel to form emulsified fuel, using the "micro-explosion" effect during combustion to promote fuel atomization, improve combustion efficiency and reduce pollutant emissions. However, oil and water are immiscible, so how to obtain a stable and fine emulsification system has always been the key technology. The introduction of ultrasonic technology provides an efficient and green physical solution for diesel emulsification.
Technical principles
The core mechanism of ultrasonic diesel emulsification is cavitation effect. When high-frequency ultrasonic waves (usually 20kHz~100kHz) propagate in liquids, periodic alternations of compression (positive pressure) and rarefaction (negative pressure) will occur. During the negative pressure stage, a large number of tiny cavitation bubbles are formed inside the liquid; during the positive pressure stage, these bubbles collapse rapidly, releasing huge amounts of energy in a very short time of nanoseconds.
The instant the bubble collapses, it can generate local high temperatures (over 5000K) and high pressures (hundreds of MPa), accompanied by strong shock waves, micro-jet flows, and shear forces. This extreme physical environment can effectively destroy the oil-water interfacial tension, break the water phase into micron or even nanometer-sized droplets, and evenly disperse in the diesel to form a stable emulsification system.
In addition to the cavitation effect, the high-frequency vibration generated by the mechanical effect of ultrasonic waves can enhance medium mixing and improve processing uniformity; the thermal effect is partially converted into heat energy by ultrasonic energy, slightly increasing the system temperature, helping to optimize processing efficiency. The three of them work synergistically to achieve efficient oil-water emulsification.
Core advantages
Compared with traditional mechanical emulsification methods (such as high-speed stirring, colloid mill, etc.), ultrasonic emulsification has significant advantages:
(1) Excellent emulsification quality. Ultrasonic waves can prepare emulsions with droplet sizes less than 1 μm and uniform particle size distribution. The particle size of microemulsified diesel prepared under optimal ultrasonic conditions can even reach 45.3nm. More than 90% of the water droplets in emulsified oil have a diameter of less than 5 microns.
(2) Stability is greatly improved. Emulsions prepared by ultrasound remain non-separated for weeks. Research shows that the stability time of emulsified diesel under the action of ultrasound can be increased from 24 hours to 72 hours.
(3) The amount of emulsifier is small. Ultrasonic emulsification can reduce the amount of emulsifier and even achieve emulsification without adding emulsifier. When using a compound emulsifier solution, the amount of emulsifier accounts for only about 2% of the micro-emulsion diesel.
(4) Significant energy saving and emission reduction effects. Emulsified diesel burns more fully and can increase thermal efficiency by 5% to 15%; reduce particulate matter emissions by 30% to 50% and nitrogen oxide emissions by 10% to 20%. In the application of forging heating furnaces, when the water content is 15%, it can save 8% of fuel and significantly reduce environmental pollution.
(5) Good operating economy. The energy consumption of ultrasonic emulsification is 40% to 60% lower than that of mechanical emulsification. The equipment is small, easy to maintain, and has a high degree of automation.
Key process parameters
The effect of ultrasonic emulsification is comprehensively affected by multiple process parameters. The following parameters need to be systematically optimized based on specific equipment and raw materials:
(1) Ultrasonic frequency. Research shows that 40kHz is an ideal operating frequency for diesel emulsification.
(2) Ultrasonic power and sound intensity. The optimal sound intensity is about 0.15~0.266W/cm². There are also studies that use voltage to express the optimal parameter as 150V. When expressed in terms of power, 220W~300W can achieve good results.
(3) Ultrasound action time. The optimal action time is usually between 10 and 25 minutes. It is worth noting that there is an optimal value for ultrasonic time—longer is not necessarily better. Excessive processing time may affect the stability of the emulsion.
(4) Water mixing rate. The water content of emulsified diesel is usually 5% to 25%. Research shows that as the water content increases, the calorific value of emulsified diesel gradually decreases, and the viscosity, flash point, fire point and freezing point increase. The maximum water content should be less than 18%.
(6) Emulsifier selection and proportioning. Commonly used emulsifiers include Span80, Tween80, sodium dodecylbenzene sulfonate, etc. The cationic surfactant cetyltrimethylammonium bromide (CTAB) has also been shown to have good emulsifying capabilities. The HLB value and dosage of emulsifier have a significant impact on emulsion stability
Main application areas
Ultrasonic emulsified diesel has shown broad application prospects in many fields:
Industrial boilers and heating furnaces. Emulsified diesel can be used as fuel for industrial furnaces such as forging heating furnaces to achieve energy saving and consumption reduction while ensuring the quality of workpieces.
Ship power. Meet the increasingly stringent emission standards of the International Maritime Organization (IMO) and reduce operating costs.
Diesel generator set. The bench test on the 75GF diesel generator shows that the maximum fuel saving rate can reach 8.24% under optimal emulsification conditions.
Mine flotation. The oil-in-water emulsified diesel produced by ultrasonic method can significantly improve the dispersion of diesel in the slurry and enhance the flotation effect of molybdenite.
Biofuel blending. Ultrasonic technology can effectively emulsify biomass oil and diesel to prepare bio-oil-diesel emulsion that can be directly used as diesel engine fuel. In recent years, the use of ultrasound-assisted preparation of stable emulsions of diesel and bio-oil has become a research hotspot.
Conclusion
Ultrasonic diesel emulsification technology uses the extreme physical environment generated by the cavitation effect to break the water phase into micron or even nanometer droplets and evenly disperse them in the diesel, achieving efficient and stable oil-water emulsification. This technology has significant advantages such as excellent emulsification quality, good stability, low emulsifier consumption, energy saving and environmental protection. It shows broad application prospects in the fields of industrial boilers, ship power, diesel power generation, mine flotation and biofuel blending. As a green physical treatment technology, ultrasonic diesel emulsification is expected to play an increasingly important role in efficient energy utilization and environmental protection.
