STUDY OF THE COAGULATION OF AEROSOL PARTICLES IN THE SCRUBBER ULTRASOUND CHAMBER

В данной работе представлены результаты исследования процесса коагуляции частиц аэрозоля моноаммонийфосфата в модельной ультразвуковой (УЗ) камере скруббера. Изучено поведение аэрозольных частиц внутри камеры на расстоянии 100 мм и 400 мм от ультразвукового излучателя с частотой излучения 22 кГц. Представленные результаты показывают практически отсутствие коагуляции частиц при интенсивности звукового давления 140 dB и процесс активной коагуляции при интенсивности звукового давления 150 dB для выбранного образца. Начальная массовая концентрация фосфата аммония в камере составляла 1 г/м3. Измерения дисперсного состава аэрозоля внутри камеры показали, что более интенсивно коагуляция проходила в области 400 мм. Через 30 минут воздействия значение среднего объемно-поверхностного диаметра частиц аэрозоля в камере изменилось на 238,4 %. This paper presents the results of the study of the coagulation of the monoammonium phosphate aerosol particles in the model ultrasonic scrubber chamber. The behavior of aerosol particles inside the chamber is studied at the distance of 100 mm and 400 mm from the ultrasonic emitter with 22 kHz of the radiation frequency. The presented results show almost complete absence of particle coagulation at the sound pressure intensity of 140 DB and the active coagulation process at the intensity of 150 dB for the selected sample. The initial mass concentration of ammonium phosphate in the chamber was 1 g / m3. Measuring the dispersed composition of the aerosol showed that coagulation proceeds more intensively in the region of 400 mm. After 30 minutes of exposure the value of the average surfactant diameter of the aerosol particles in the chamber has changed by 238.4%.

The Limits of Fine Particle Ultrasonic Coagulation

This paper describes the studies conducted in order to identify the limits of ultrasonic exposure’s effect on the fine particle coagulation process. It has been established as a result of the studies that ultrasonic exposure with a sound pressure level of 160 dB is capable of ensuring coagulation of particles sized 2.5 µm with efficiency δ = 83%. An increase of the coagulation up to 13% is induced with generation of swirling flows. The suggested approach to increasing the coagulation efficiency owing to vortex-type flows between the radiating and reflecting surfaces ensures efficiency of coagulation δ = 96 %. The implementation of this approach has shown that with generation of vortex-type acoustic flows, it makes the most sense for a concentration of particles of 18×10−3 g/m3. Incremental efficiency at such concentrations amounts to 50%.

On the spatially inhomogeneous particle coagulation-condensation model with singularity

The spatially inhomogeneous coagulation-condensation process is an interesting topic of study as the phenomenon’s mathematical aspects mostly undiscovered and has multitudinous empirical applications. In this present exposition, we exhibit the existence of a continuous solution for the corresponding model with the following \emph{singular} type coagulation kernel: \[K(x,y)~\le~\frac{\left( x + y\right)^\theta}{\left(xy\right)^\mu}, ~~\text{for} ~x, y \in (0,\infty), \text{where}~ \mu \in \left[0,\tfrac{1}{2}\right] \text{ and } ~\theta \in [0, 1].\] The above-mentioned form of the coagulation kernel includes several practical-oriented kernels. Finally, uniqueness of the solution is also investigated.

A new weighted fraction Monte Carlo method for particle coagulation

Purpose The purpose of this study is to investigate the aerosol dynamics of the particle coagulation process using a newly developed weighted fraction Monte Carlo (WFMC) method. Design/methodology/approach The weighted numerical particles are adopted in a similar manner to the multi-Monte Carlo (MMC) method, with the addition of a new fraction function (α). Probabilistic removal is also introduced to maintain a constant number scheme. Findings Three typical cases with constant kernel, free-molecular coagulation kernel and different initial distributions for particle coagulation are simulated and validated. The results show an excellent agreement between the Monte Carlo (MC) method and the corresponding analytical solutions or sectional method results. Further numerical results show that the critical stochastic error in the newly proposed WFMC method is significantly reduced when compared with the traditional MMC method for higher-order moments with only a slight increase in computational cost. The particle size distribution is also found to extend for the larger size regime with the WFMC method, which is traditionally insufficient in the classical direct simulation MC and MMC methods. The effects of different fraction functions on the weight function are also investigated. Originality Value Stochastic error is inevitable in MC simulations of aerosol dynamics. To minimize this critical stochastic error, many algorithms, such as MMC method, have been proposed. However, the weight of the numerical particles is not adjustable. This newly developed algorithm with an adjustable weight of the numerical particles can provide improved stochastic error reduction.

Влияние осаждения и коагуляции частиц на параметры текущих в трубе наноаэрозолей

The influence of the processes of deposition and coagulation of particles, caused by Brownian diffusion, on the parameters of aerosols flowing in the tube is studied. The problem is considered in a two-dimensional formulation taking into account the inhomogeneous velocity profile of the medium across the tube. At different Knudsen numbers, the distributions of the concentration and radius of clusters (formed due to particle coagulation) along the longitudinal and transverse directions were obtained by the numerical finite difference method. It was found that moving along the channel, the clusters reach the final (limiting) size. The influence of the governing parameters on the distribution of dispersed characteristics of the mixture inside the tube and on the limiting size of clusters is discussed.