Experimental investigation of acoustic agglomeration of diesel engine exhaust particles using new created acoustic chamber

Journal Pre-proof Experimental investigation of acoustic agglomeration of diesel engine exhaust particles using new created acoustic chamber Kristina Kilikevičienė, Rimantas Kačianauskas, Artūras Kilikevičius, Algirdas Maknickas, Jonas Matijošius, Alfredas Rimkus, Darius Vainorius PII:

S0032-5910(19)30786-7

DOI:

https://doi.org/10.1016/j.powtec.2019.09.057

Reference:

PTEC 14731

To appear in:

Powder Technology

Received Date: 27 February 2019 Revised Date:

13 August 2019

Accepted Date: 18 September 2019

Please cite this article as: K. Kilikevičienė, R. Kačianauskas, Artū. Kilikevičius, A. Maknickas, J. Matijošius, A. Rimkus, D. Vainorius, Experimental investigation of acoustic agglomeration of diesel engine exhaust particles using new created acoustic chamber, Powder Technology (2019), doi: https:// doi.org/10.1016/j.powtec.2019.09.057. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier B.V.

EXPERIMENTAL INVESTIGATION OF ACOUSTIC AGGLOMERATION OF DIESEL ENGINE EXHAUST PARTICLES USING NEW CREATED ACOUSTIC CHAMBER 1)

Kristina Kilikevičienė, 2) Rimantas Kačianauskas, 3) Artūras Kilikevičius, 4) Algirdas Maknickas, 5)

1)

Jonas Matijošius *, 6)Alfredas Rimkus, 7) Darius Vainorius

Department of Mechanical and Material Engineering, Faculty of Mechanical Engineering, Vilnius Gediminas Technical University Basanavičiaus str. 28, LT-03224 Vilnius, Lithuania

2), 3), 4), 5), 7)

Institute of Mechanical science, Faculty of Mechanical Engineering, Vilnius Gediminas Technical University Basanavičiaus str. 28, LT-03224 Vilnius, Lithuania

6)

Department of Automobile Engineering, Faculty of Transport Engineering, Vilnius Gediminas Technical University Basanavičiaus str. 28, LT-03224 Vilnius, Lithuania

1)

[email protected], 2) [email protected], 3) [email protected], 4)

[email protected], 5) [email protected] *, 6) [email protected], 7)

[email protected] * Corresponding author

Abstract. Many researchers have considered air quality degradation due to the emission of fine particles from industrialized and urban areas during recent decades. Recently, the European Parliament has had concerns about ensuring a healthy human environment. Therefore, the experimental and theoretical investigations of the dynamics of fine particulate matter are for determining efficient monitoring and cleaning air from industrially generated air pollutants. These investigations also imply the use of alternate methods that stimulate fine particle agglomeration. One of the methods is the use of acoustics. Many experimental investigations of particles with a diameter between 1 and 10 µm have proven that the use of acoustic agglomeration increases the particle size. Then, conventional air filters can be used to collect the larger particles. This process improves the collection efficiency of the particles. Particulate agglomeration chamber consisting of an acoustic field generator and an inner part was created for the test particles of diesel engines (range from 0.3 to 10 µm). Modeling of its elements was performed using Comsol multifunctional software. This sound pressure level is enough [1] to lead the acoustic agglomeration process of particles in the measurable range from 0.3 to 10 µm. The sound pressure level reach this value (130–140 dB) at the acoustic agglomeration zone. Additionally, the theoretical evaluation of the agglomeration time of two sub-micron particles enabled the estimation of efficient agglomeration of particles with sizes between 0.3 to 10 µm during the measurement period. A starting value of 136 dB of sound pressure level (SPL) was created in the experimental chamber with the turbulence condition, where SPL values were measured by using the Bruel&Kjaer measurement system “Type 9727” with hydrophone 8104. The

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observation concentrations of diesel engine exhaust particles in the experimental chamber with and without acoustic influence were performed using Particle Concentration Analyzer 4 APC ErgoTouch Pro 2. The results of experimental research shows that the acoustic agglomeration effect formed the proper conditions for the agglomeration of particles of all diameters (0.3, 0.5, 1.0, 3.0, 5.0 and 10 µm).

Keywords: CI engine, engine exhaust emission, particles, acoustic agglomeration, piezoelectric acoustic transmitter, experimental measurements.

1. Introduction

As was mentioned in” Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe”, fine particulate matter (PM) is responsible for significant negative impacts on human health [2–5]. According statistics the road traffic emission is the most hazardous sources of atmospheric pollution [6–9]. The main source of this kind of emission is emission of particulate matter (PM) [10]. The recent year shows the huge urban development with a complex of natural-technologicalsocial problems. The solution of it is a complex environmental activities of decreasing PM emission [11–12]. Vehicle emissions are an important source of anthropogenic aerosol particles. Diesel particulates and other sources of fossil fuel combustion are a complex combination of elemental carbon, various hydrocarbons, sulfur compounds, and other types [13–17]. These particles differ in size, composition, solubility and toxicity. Discharges of diesel fuel are considered to be particularly harmful, and various toxicological and epidemiological studies have shown their adverse effects on human health [18]. Typical diesel particles are spherical agglomerates that mainly have a diameter between 30 to 500 nm in diameter [19], the diesel exhaust also contains larger particles up to 10 µm in the exhaust stream. One way to reduce the number of small particles is by acoustic agglomeration. Acoustic agglomeration is the process whereby acoustic waves are used to influence the movement of particles in the air [20–23], thereby promoting particle collisions and the formation of larger agglomerates (particle compounds). The newly formed agglomerates continue to agglomerate with each other and cause cascade particle growth. Acoustic agglomeration is most effective in possible mechanisms for transmitting different particles [24–28]. Acoustic agglomeration technology is used for the treatment of high-density particles of liquid and gaseous media in industries such as chemical processing, oil and gas, food production and environmental pollution control [29], [30–33]. Particular attention is paid to fine particulates because they comprise a significant

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proportion of the emissions of particles that are difficult to remove by using other technologies. For example, the efficiency of cyclones that are used for controlling industrial combustion emissions and collecting fine particles (diameters less than 5 µm) is less than 40% [34–35]. In addition to industrial emissions control, it is also possible to use ACMV (air-conditioning and mechanical ventilation) systems for the removal of particulates and bioaerosols when the typical filter performance is low when the particle size is from 0.01 µm to 2 µm [4, 29]. The hypothesis is that fine PM and bioaerosols can be preconditioned by acoustic agglomeration to produce larger agglomerates that can be more easily removed by filtration [36–39]. In the neighbored area HVAC (Heating, Ventilation and Air Conditioning) electret filters are known. Those provide high filtration efficiency in the mentioned size range [40]. The simple solution of the decreasing pollution of PM is to use acoustic agglomeration. Acoustic agglomeration is the process whereby acoustic waves are used to influence the movement of particles in the fluidized environment, including aerosols [41–45]. The high-intensity sound waves forces particles to vibrate with the surrounding medium under different amplitudes. Relative movement between particles makes them approach each other. The binary interaction of particles under sound waves induced oscillatory flow was research in many studies [45–48]. The solution for binary interaction of two particles via an interstitial substance was applied for numerical direct integration [44, 49–51], and the time-accurate DEM models [30, 42–44]. The general idea of this article is the investigation of particle agglomeration in the acoustic field. The authors in the current topic have performed their theoretical investigations by using the DEM-based theoretical model, which shows good agglomeration results and made assumptions for experimental research of acoustic particle agglomeration. The pilot studies of the newly developed unit are carried out and the aim of the research is to cover as wide a measuring range as possible (considering particle diameters), which is why the diesel exhaust gas flow (as particle flow generator of different diameters) was chosen in this paper. This article investigated a newly designed acoustic agglomeration chamber that consists of an acoustic field generator and internal agglomeration zone for particles ranging between 0.3 and 10 µm. The authors describe the modelling details of the acoustic chamber elements by using Comsol multiphysics software, on which the real layout was developed. As a source of submicron particles, a diesel engine was used, and the experience of previous studies performed at the Mechanics Research Institute and the Department of Automotive Engineering, VGTU, was considered. In addition, the results of the theoretical particle agglomeration model, which was required for pre-model experiment, are presented based on specific environmental conditions.

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In this work, acoustics-based experiments were performed on the agglomeration of particles in the diesel engine discharges, for which the specially designed chamber was created for collecting the emission of diesel engine aerosols and incorporating the acoustic effects. The theoretical investigation determined the adequacy of the acoustic field frequency impact and exposure time selection during the experiment. The effect of acoustic agglomeration on the agglomeration of particles contained in the exhaust gases of the engine has been investigated. The results show that acoustic agglomeration has a significant positive effect on improving the agglomeration efficiency of solid particles and aerosols contained in the engine exhaust. The compressed ignition (diesel) engine is the biggest source of PM from the traffic flow [53]. This is the main reason why was chosen the high frequency of acoustic wave. The benefit of high frequency (from 20 kHz) lies in the analyses of literature where acoustic generators had more than 20 kHz frequency [18, 25]. On the another hand these type of generators were manufactured at serial production and the cost of them are very low. 2. Theoretical background

Various theoretical and experimental works have been performed to demonstrate the efficiency of acoustic agglomeration [19, 36, 54–55]. However, the results are not completely consistent due to complex mechanisms and different experimental conditions. In experimental research on acoustic agglomeration, scientists usually identify optimal acoustic agglomeration conditions and additionally assess the influence of other factors [19, 33, 35]. However, few studies have been performed to demonstrate the positive effects of sound waves on engine exhaust systems that are closely related to large-scale transport and industrial applications. The adequacy of comparison between simulation and experimental results is very important aspect of PM research. The validation of these results has shown the very similar meanings of the data and the difference of results were as a result of experimental conditions, particle properties, application areas and soundwave parameters [24, 56]. There were a lot of research of dust [57] and coal [32, 34] that show the adequate research methodology. From the review of acoustics agglomeration in previous sections, it is determined that at least 140 dB is required with sufficient residence time for any changes in particle size distribution to be observed and standing waves are preferred for particle drift towards nodes. These are parameters considered for the feasibility study. Other influencing parameters such as the addition of seed particles, turbulence, humidity, etc. are not

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explored in this preliminary investigation, but will be considered in future studies [37] standing wave, high frequency, [38, 59]. The translational motion of an arbitrary particle p with mass mp in incompressible media under acoustically induced excitation is described in a Cartesian frame of reference and obeys Newton’s second law. The proposed model assumes that the particle system does not influence fluid motion. Consequently, the conventional DEM approach was modified for simulation purposes. The approach used in our article is based on alternating method , when fluid motion is governing by acoustic excitation and motion of particles is described by analytically obtained fluid forces applied to the each particle. The research results of previous investigations show correctness of usage such kind of approach to the particle motion in fluids too. . The approach is characterised by the position and velocity vectors of the spherical particle centre xp(t) and up(t), respectively, and its motion can be described as follows:




 

=  +  + 

(1)

The contribution of the flow velocities is characterised by the total [59] drag force  . The gravity force  and the buoyancy force  are vertical forces:

 = V  ,

(2)

 = −V  ,

(3)

where Vp is particle volume, g is gravity acceleration of free fall and ρair, ρp denote the density of the gas media and the particle, respectively. The interaction of each particle with the acoustic field (i.e. orthokinetic collisions) is described in Dong et al.

[60]. For a sinusoidal sound wave, the acoustic velocity is as follows:  =   sin −  !",

(4)

where  is the gas media velocity amplitude, while  is the angular frequency  = 2$%, where f is the sound frequency and kx is the wavenumber expressed as  = /( . The sound pressure amplitude is related to the acoustic velocity by ) =  (  , where  is the gas media density, ( is the sound velocity, and  is the

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entrainment factor, where the entrainment factor denotes the particle entrainment factor or the ratio of particle velocity and the amplitude velocity of oscillating air flow [58] and for particles of diameter 0.3 µm in the acoustic field with a frequency of 24 kHz in air that equals 0.998. Oseen [59] proposed the acoustic wake effect for a sphere flowing in vibrating fluid a system of equations that describes two particles in the global coordinate system as follows:

 = 6$+,- .- 1 +

01234 53 67

∣ ,- ∣",

(5)

where .- is the radius of the particle, + is the dynamic viscosity of the medium, and ,- =  - − - denotes the difference between the velocities of the medium and of the particle (slip-flow velocity). There exists the analytical solution of the radial 9 and angular 9: velocities of the flow around the sphere under the Oseen conditions [59]. If the terms of a power ; 0 are ignored, then we obtain new equations for slip-flow velocity around the moving sphere [46]: ?@ BCD4EFGHIJ"

v= =

>?@

vP =

?@ Q-RP >T=UVWXQP" e K=

A

+

KL A

1 + ;1 − cosO"" + - cosO

(6)

− U- cosθ,

(7)

where

A\ =

0]^3 53 _1 K∣∣^3 ∣

+

053 6]

∣- ∣`.

(8)

For calculating the hydrodynamic interaction between aerosol particles in a sound field under Oseen flow conditions, Danilov et al. [55] proposed the expression of gas media velocity as follows:

 - = \ sin + 9-b

(9)

where the quantity 9L accounts for the variation of the vibrational velocity of the medium at the site of the i-th particle due to the influence of the slip-flow field associated with the j-th particle. The slip-flow velocity field was described for the Oseen condition by Equations (6) and (7).

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The dependence between entrainment coefficient and frequency is presented on Fig.1. Fig. 1 Dependence of the entrainment coefficient on the frequency in the Oseen flow

The Figure 1 shows that when there are high frequencies (over 20 kHz) the entrainment factor pushes towards 1 especially in small particles case. The chosen frequency is 24 kHz because currently there are industrially produced frequency generators with an optimal price / quality ratio. Detail description of numeric solution methods can be found in [61]. Fig. 2 presents the numeric solution of the equation of motion for two particles in an acoustic field with a frequency of 24 kHz. Other parameters are as follows: diameter of the particles is 0.3 µm, SPL = 136.6 dB, initial distance D between particles ~300 µm, particles are in air fluid. An average distance between particles was obtained by dividing total measured volume by measured total amount of particles in the chamber and taking one-third root of them c ≈

E/h

ef/g . The result

shows that two particles agglomeration time is approximately 30 s, implying that experiment duration for similar particle densities for above a defined sound pressure level and acoustic excitation time should exceed theoretical agglomeration time. Fig 2. Two particles motion in the acoustic field, coordinate x projection.

3. Equipment and methodology and validation

The experimental stand consists of a diesel engine, acoustic chamber (agglomeration zone) and particle number and acoustic measurement equipment. The design of the acoustic camera allows the sound pressure level to reach 140 dB (at a frequency of 24 kHz). The choice of frequency for an acoustic generator was based on two causes. First, an entrainment factor in the acoustics field with a frequency of 24 kHz is approximately 1. As a consequence, we have maximised orthokinetic agglomeration. The second, the acoustic generators with a highpressure level and frequencies of 24 kHz and 40 kHz are easily accessible in the market. The choice of frequency of 24 kHz is justified as follows. The partition concerts and sound pressure measurements are monitored after the acoustic chamber (agglomeration zone). Experiments are performed to investigate PM concentrations when they are acoustic and non-acoustic. The sound presssure level is monitored during each experiment. For each experiment, the sound pressure, temperature and particle concentration were measured for 30 seconds. The number of particles deposited on the walls is not considered because it is insignificant compared to the total particle concentration [62]. To achieve a stable aerosol flow, a working diesel engine

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condition was achieved, i.e. during the tests, constant conditions were maintained in the engine and measurements were made when the engine was being prepared for testing (i.e. engine warm-up process). Engine testing bench. Experimental research was equipped with tools of the laboratory of the VGTU Mechanics Research Institute and the Department of Automotive Engineering. A detailed description of the engine operating principles used in the experiment is provided [63].

Diesel fuel used for testing. The fuel physical and chemical properties studied in the laboratory and their properties are given in Table 1. Table 1

Basic physical and chemical properties of diesel fuel. Acoustic chamber. An acoustic chamber was designed for investigating acoustic particle agglomeration. The acoustic chamber consists of a piezoelectric excitement source and an T – form pipe. These two elements were designed and optimised using the Comsol multiphysics software. The objective of the design is to achieve a sound pressure level of at least 140 dB in the acoustic chamber, and the results obtained are presented in Fig. 3. Based on these calculations, an acoustic camera was designed and manufactured. For the acoustic effects parameters and particle size measurement, the equipment used is shown in Fig. 4. The block diagram of the test stand is given in Fig. 5. Fig. 3 Results obtained during the design of the Acoustic Camera:

a – Mesh; b – Total displacement (mm); c – Far-Field sound pressure level (dB); d – Far-Field sound pressure level Isosurface (dB).

Fig. 4 Test bench scheme:

1-particle concentration analyzer 4 APC ErgoTouch Pro 2, 2 - Acoustic emission generation and measurement zone, 3 Diesel engine, 4 - Bruel & Kjær data processing system Type 9727.

Fig. 5 Test block diagram

There were used Particle Concentration Analyzer 4 APC ErgoTouch Pro was calibrated with the following equipment Scattered-Light Aerosol Spectrometer System Promo® 3000. % l / min) and the results were within

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5%. In addition to the fact that the article focuses on evaluating the impact of acoustic impact on particle agglomeration, it can be said that the accuracy of the equipment used in the study is sufficient. Product Specification presented in the 2 Table. Table 2

The main parameters of Particle Concentration Analyzer 4 APC ErgoTouch During the research, the emissions from the diesel engine were exposed to a 136-dB sound pressure in the acoustic chamber. Sound pressure and temperature were measured in the acoustic chamber (the temperature in the acoustic chamber was 29.2 ± 0.5 °C during measurement). After the acoustic chamber, the concentration of the particles in the stream was measured when the acoustic chamber had acoustic action and no exposure. The Bruel & Kjær measuring system Type 9727 (Fig. 6, Item 4), which consists of the universal Type 7910 software, the Type PULSE 3560-B multichannel data unit, the Dell personal laptop, was used to estimate the acoustic field parameters. The computer and Bruel & Kjær hydrophone 8104 (sensitivity 211 dB 1 V / µPa ± 2 dB, frequency response from 0.1 Hz to 100 kHz + 1.5 / -6.0 dB, 0.1 Hz to 180 kHz + 3.5 / -12.5 dB; in the horizontal direction (xy plane) ± 2 dB at 100 kHz; in the vertical direction (xz plane) ± 4 dB at 100 kHz) were used. The number of particles with and without acoustic action is measured with a particle concentration analyzer, and four APC ErgoTouch Pro 2 (measured particle diameter - 0.3 µm, 0.5 µm, 1 µm, 3 µm, 5 µm, 10 µm, measuring time - 30 seconds, feed air flow rate at 1.0 ± 5% l / min) devices were used.

4. Results and discussion In the acoustic chamber during the study, the acoustic field sound pressure level was 136.6 dB at a 24 kHz frequency when the piezoelectric generator was operating (Fig. 6). The partitioning of particulates is presented in Figure 7 and Table 2. Analyzing Figure 6 data shows that the piezoelectric sound generator generates a sound pressure level of 135 dB (24 kHz). When evaluating the change in the sound pressure amplitude, the increase is about 6 times (from 40 to 240 Pa). Fig. 6 Acoustic Field Parameters:

(a) Time-based sound pressure level; (b) The spectrum tank schedule

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Fig. 7 Comparison of particles amount without acoustics to particles amount in the acoustic field

Fig. 8 Relative amount of particles without acoustics to particles in the acoustic field Table3

Particulate concentration by diameter The curves in Figure 7 show the distribution of the relative particle amount according to the particle diameter exposed to acoustic excitation. Particle measurements were performed during the study (after six measurements, and the mean experimental values are shown in Fig. 8 and Table 2) when the engine was in working condition (constant parameters: load 45 kNm, turning 2000 rpm, engine oil temperature 98 ℃, intake air flow rate 131.7 kg / hr., fuel consumption 2.75 kg / h). When the particle quantities are evaluated, the acoustic effect has made it suitable for the agglomeration of particles with all diameters. In the studies, the temperature in the acoustic chamber was 29.2 ℃ when the engine was in working condition. The number of particles increased from 1.7 to 5 times. The evaluation of particles amount (Fig 7) shows, that particle amount of diameter 10 µm and uncertainty of experiment measurement has approximately the same values and such small amount of particles (when evaluating particles amount of diameter 10 µm in diesel engine exhaust) reliability of results can be too small. Therefore, concluding evaluation should be done without results of diameter 10 µm particles. The performed studies indicate that the created acoustic chamber is an effective means for the agglomeration of small diameter particles. The phenomenon of agglomeration depends on the frequency, and the agglomeration in the ultrasound domain might have somewhat different results, which is the object of further experimental research with another acoustic system when controlling a higher number of process parameters (e.g. temperature and humidity). The comparison of measurements by the ratio of the number of particles in the acoustic field and without it can be divided into three zones: particles with diameters from 0.3 to 0.5 µm, particles with diameters from 0.5 to 3 µm and particles with diameters from 3 to 10 µm. Particles in the first region demonstrate a decreasing number of particles. The relative amount of particles in the second region is approximately flat. The relative number of particles in the region of biggest diameters increasingly depends on particle diameters. Obviously, an increasing number of particles in the last region can be explained by the inflow of growing diameters during particleacoustic agglomeration. Furthermore, a behaviour of intermediate region can be explained by the equivalence of

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inflow and outflow of particles with according diameters. Finally, particles in the region with the smallest diameters agglomerate and form particles of larger diameters.

4. Conclusions A complex research relationship between engine working parameters, vibration of engine points, sound pressure and particles meter measurements is presented in this research. The paper describes complex investigations, which include: design and characterization of a newly developed acoustic chamber, and acoustic field agglomeration studies of the particles in the diesel engine exhaust stream. An acoustic generator was created for the generation of the sound pressure (130–140 dB) in the acoustic agglomeration zone. The evaluation of the relative amount of particles in the acoustic field shows that the acoustic effect formed the proper conditions for the agglomeration of particles of all diameters (0.3, 0.5, 1.0, 3.0, 5.0 and 10 µm). The data of obtained measurements indicate that the diameters of particles in an acoustic field shift to the larger diameters, and the highest relative increase was observed for the particles of 0.3 and 5 µm where it was reached 3 times. The performed studies indicate that the created acoustic chamber is an effective means for agglomerating small diameter particles.

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Table 1

Basic physical and chemical properties of diesel fuel.

Fuel Properties Density at 15°C, g/ml

0.838

Dynamic viscosity at 15°C, mPa·s

4.441

Kinematic viscosity at 15°C, mm2/s

5.302

Water content acc. CF, %

0.0028

Mass content of hydrogen, %

13.31

Mass content of carbon, %

86.69

Filtration temp., °C

-22

Flowability temp., C

-39

Cetane number

53

Lower heating value, MJ/kg

42.83

Table 2

The main parameters of Particle Concentration Analyzer 4 APC ErgoTouch

The parameters

The meaning of the parameter

Brand

Welas

Size

Dimensions 185 * 450 * 315 mm (19 inch)

Features

Software PDControl, FTControl, PDAnalyze

Spectral Resolution

Time resolution Up to 1 s

Minimum Order Quantity

10 Piece

Measurement range (size)

0.2 µm – 10 µm

Channel Sizes

Standard: 0.3 to 10 µm, user-selectable

Flow Rate

0.1 CFM (2.83 L/min) with ±5% accuracy (meets JIS and ISO 21501-4 requirements)

Counting Efficiency

50% at 0.3 µm; 100% for particles > 0.45 µm (per JIS and ISO 21501-4)

Concentration Limits

2,000,000 particles/ft3 at 5% coincidence loss

20

Light Source

Long life laser diode

Zero Count Level

<1 count/5 minutes (per JIS B9921 and ISO 21501-4)

Calibration

NIST traceable with Millipore calibration system

Battery

Removable/rechargeable Li-Ion

Housing material

High impact injection molded plastic

Sampling Modes

Manual, automatic, beep, cumulative/differential count or concentration

Table 3

Particulate concentration by diameter Total amount of particles in 166.645 (cm3) volume, number Particle Diameter

0.3 µm

0.5 µm

1.0 µm

3 µm

5 µm

10 µm

With acoustic influence

25391

20381

13269

152

16

1

Without acoustic influence

77680

47973

30097

269

48

5

306 %

235 %

227 %

177 %

300 %

500 %

Engine working conditions

Difference (with acoustic influence/ Without acoustic influence)*100 %

21

Fig. 1 Dependence of the entrainment coefficient on the frequency in the Oseen flow

Fig 2. Two particles motion in the acoustic field, coordinate x projection.

22

a)

b)

c)

d)

Fig. 3 Results obtained during the design of the Acoustic Camera: a – Mesh; b – Total displacement (mm); c – Far-Field sound pressure level (dB); d – Far-Field sound pressure level Isosurface (dB).

2 1

23

3 4

Fig. 4 Test bench scheme: 1-particle concentration analyzer 4 APC ErgoTouch Pro 2, 2 - Acoustic emission generation and measurement zone, 3 Diesel engine, 4 - Bruel & Kjær data processing system Type 9727.

Fig. 5 Test block diagram.

24

Fig. 6 Acoustic Field Parameters: (a) Time-based sound pressure level; (b) The spectrum tank schedule (red – without acoustics; blue – with acoustics)

µm

Fig. 7 Comparison of particles amount without acoustics to particles amount in the acoustic field

µm

Fig. 8 Relative amount of particles without acoustics to particles in the acoustic field

25

EXPERIMENTAL INVESTIGATION OF ACOUSTIC AGGLOMERATION OF DIESEL ENGINE EXHAUST PARTICLES USING NEW CREATED ACOUSTIC CHAMBER 1)

Kristina Kilikevičienė, 2) Rimantas Kačianauskas, 3) Artūras Kilikevičius, 4) Algirdas Maknickas, 5)

1)

Jonas Matijošius *, 6)Alfredas Rimkus, 7) Darius Vainorius

Department of Mechanical and material Engineering, Faculty of Mechanical Engineering, Vilnius Gediminas Technical University Basanavičiaus str. 28, LT-03224 Vilnius, Lithuania

2), 3), 4), 5), 7)

Institute of Mechanical science, Faculty of Mechanical Engineering, Vilnius Gediminas Technical University Basanavičiaus str. 28, LT-03224 Vilnius, Lithuania

6)

Department of Automobile Engineering, Faculty of Transport Engineering, Vilnius Gediminas Technical University Basanavičiaus str. 28, LT-03224 Vilnius, Lithuania

1)

[email protected], 2) [email protected], 3) [email protected], 4)

[email protected], 5) [email protected] *, 6) [email protected], 7)

[email protected] * Corresponding author

•

The IC (internal combustion) engine exhaust particle emissions are considered.

•

An acoustic generator for the agglomeration of particles was created and validated.

•

Acoustic agglomeration produces about 140 dB of sound pressure at 24 kHz frequency.

•

The agglomeration of particles (0.3 – 10 µm) approved by experimental studies.