Application of Acoustic Agglomeration Technology to Improve the Removal of Submicron Particles from Vehicle Exhaust

Abstract

The natural processes of interactions between aerosol particles in the ambient air through which they agglomerate is a vast area of chamber research and are inherent to many industries and are often inter-connected with transport engineering. Further improvement of symmetric methods for aerosol particle number and mass concentration reduction made it possible to create various synergic techniques. The study used a 1.9 TDI diesel internal combustion engine, which was supplied with diesel (D100) and second-generation biofuels (NExBTL100) with the EGR exhaust system on and off. Measurements were performed using a Bruel and Kjær “Type 9727” system for measurement of vibrations, a scanning mobility particle sizer (SMPS) and an original agglomeration chamber. The three modes of particle size distributions were observed in the size range from 10 to 470 nm for both D100 and NExBTL100 fuels with and without the use of the EGR system. The application of 21.3 kHz frequency sound with SPL 144.1 dB changed the NExBTL100 generated aerosol particle number concentration but did not sufficiently affect the concentration of D100 emitted particles. The greatest agglomeration effect (21.7 ± 10.0%) was observed in the range of extremely small NExBTL100 derived particles (10–70 nm) when used in combination with an EGR system.

Agglomeration of particulate matter in chimneys using acoustic flow

“…In recent decades extensive experimental studies have been carried out on the acoustic agglomeration of various aerosols. Studies analyzing coal-fired exhaust gases [ 22 ], variants of diesel fuel exhaust gas [ [23] , [24] , [25] ], flue gas [ [26] , [27] , [28] ] and liquid aerosols [ 23 ] have demonstrated sufficiently high agglomeration efficiency. The acoustic frequencies used in the literature vary widely, ranging from 46 Hz to 21 kHz.…”

“…Frequencies between 1 and 3 kHz are favorable for micron and submicron-sized aerosol particles, such as coal-fired fly ash. However, ultrasound with a frequency greater than 10 kHz is more effective for exhaust gas from internal combustion engines containing nanometer and submicrometer-sized particles [ [23] , [24] , [25] ].…”

“…However, progress in understanding the agglomeration mechanisms necessary for optimizing acoustic agglomeration processes has been slow compared to experimental research. Many researchers have devoted significant attention to the study of acoustic agglomeration methods [ [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] ]. The important principles of acoustic agglomeration can be illustrated as follows: sound waves propagate through the aerosol, causing relative movement of particles and increasing the probability of collisions.…”

Improving Inhalation Performance with Particle Agglomeration via Combining Mechanical Dry Coating and Ultrasonic Vibration

“…the vibration of fine particles to generate interparticle collisions, resulting in particle agglomeration [18]. This is advantageous for producing agglomerates with loose microstructures that are ready for dispersion, because the spherical agglomerates are subject to continuous rotation during spheroidization, during which the agglomerates slide from the bottom of the coating pan (as shown in Figure 1A,B).…”

“…To solve the problems that occur during the conventional production of agglomerate formulations, achieving particle agglomeration under ultrasonic vibration is an alternative for the continuous production of agglomerate formulations with efficient deagglomeration and fine particle dispersion, which was originally reported for the collection of particulate matter of 2.5 μm or less in diameter [ 17 ]. Strong aerial ultrasonic waves induce the vibration of fine particles to generate interparticle collisions, resulting in particle agglomeration [ 18 ]. This is advantageous for producing agglomerates with loose microstructures that are ready for dispersion, because the spherical agglomerates are subject to continuous rotation during spheroidization, during which the agglomerates slide from the bottom of the coating pan (as shown in Figure 1 A,B).…”