This document is the final report for a project constructing a bifurcation tube to simulate non-spherical particulate deposition in the human respiratory system. It describes the experimental setup including the bifurcation tube, microfeeder, ejector, and logic controller box used to introduce particles into the tube at controlled intervals. Characterization of the particle samples using SEM and BET analysis is also summarized. Results are presented on deposition fractions of particles in different regions of the tube under flow rates and intervals simulating human breathing at rest, working while lying down, and working while upright.

1. Department of Chemical & Biomolecular Engineering
THE NATIONAL UNIVERSITY
OF SINGAPORE
CN4118R Final Report
Constructionof bifurcation tube for simulation of non-spherical particulate
deposition in the human respiratory system
Name: Fu Ruiqi (A0111590R)
Date of submission: 13th Jan 2017

2. i
Acknowledgements
I would like to express my sincere gratitude towards the following individuals without them
this Final Year Project will not come to fruition.
Professor Wang Chi-Hwa for providing the lab space, equipment and expertise in this field.
Associate Professor Yang Kun-Lin for sharing his lab equipment.
Dr. You Siming for his guidance and direction during the project.
Mr. Zhan Guowu for his help on the BET and SEM machines.
Mr. Noel for running through the general experimental concepts.
Mr. Qin Zhen for his help in troubleshooting the rotameter and gas regulators.
Mr. Kinnosuke Watanabe (Sankyo Pio-Tech Co., Ltd.) for the support on the microfeeder.
Mr. Chua Chin Tian (Dong Sheng Hardware PTE. Ltd.) for the mechanical supports.
Ms. Lim Kwee Mei for the general and administrative assistance.
And all who had helped me in one way or another throughout this past 6 months.

3. ii
Contents
Acknowledgements .......................................................................................................................i
List of tables................................................................................................................................iii
List of figures............................................................................................................................... iv
List of abbreviations...................................................................................................................... v
Abstract......................................................................................................................................vi
1. Introduction ............................................................................................................................. 1
2. Literature Review...................................................................................................................... 3
2.1 The human respiratory system............................................................................................. 3
2.2 Transport Principles and Fluid Dynamics............................................................................... 4
2.3 Total vs local depositions.....................................................................................................5
2.4 Flow rates, orientation and other considerations ..................................................................6
3. Apparatus, Equipment and Methods.......................................................................................... 7
3.1 Overview of Experimental Set-up......................................................................................... 7
3.2 Bifurcation Tube.................................................................................................................. 8
3.3 Microfeeder........................................................................................................................ 9
3.4 Ejector.............................................................................................................................. 11
3.5 Logic Controller Box (LCB).................................................................................................. 12
3.6 Usage of Laser for Measurement........................................................................................ 13
3.7 Definition of Co-ordinates.................................................................................................. 15
4. Characterisation of Particle Samples ........................................................................................ 16
4.1 Scanning Electron Microscope (SEM).................................................................................. 16
4.2 Brunauer–Emmett–Teller (BET) Machine............................................................................ 20
5. Results and Discussion ............................................................................................................ 21
5.1 Human at rest (Flow Rate: 10 L/min, Interval: 4 seconds)..................................................... 21
5.2 Working laying down (Flow Rate: 25 L/min, Interval: 2 seconds) .......................................... 24
5.3 Working upright (Flow Rate: 25 L/min, Interval: 2 seconds).................................................. 26
6. Current Problems and Future Directions................................................................................... 29
7. Conclusion.............................................................................................................................. 30
8. References ............................................................................................................................. 31
9. Appendices............................................................................................................................. 34
9.1 Appendix A SEMmicrographs ............................................................................................ 34
9.2 Appendix B Histograms of Particle Size Distributions ........................................................... 37
9.3 Appendix C Deposition Patterns......................................................................................... 39
9.4 Appendix D Deposition Measurements............................................................................... 42
9.5 Appendix E Particles Pixel Area........................................................................................... 42

4. iii
List of tables
Table 1. Summary of various analytical methods .....................................................................5
Table 2. Summary of Vernier Calliper Measurements .............................................................9
Table 3. Particle Characteristics..............................................................................................20
Table 4. Summary of weighing measurement and total percentage deposition......................24

5. iv
List of figures
Figure 1. Schematics of the human respiratory system. ...........................................................3
Figure 2. Illustration of Experimental Set-Up. .........................................................................7
Figure 3. Actual Experimental Set-Up......................................................................................8
Figure 4. Bifurcation glass tube ................................................................................................8
Figure 5. Microfeeder..............................................................................................................10
Figure 6. Graph of Discharge Rate against Turn Table RPM.................................................11
Figure 7. Ejector and its principle...........................................................................................11
Figure 8. PLC interior view with all wires connected ............................................................12
Figure 9. Extended Function Block Program..........................................................................13
Figure 10. The 5 mediums affecting the laser intensity..........................................................14
Figure 11. Two directions of measurements. ..........................................................................16
Figure 12. Particle samples under various SEM magnifications ............................................17
Figure 13. Outlines of samples ii and iii. ................................................................................18
Figure 14. Particles’ size distribution for samples i, iii, iv and v............................................19
Figure 15. Deposition Fraction in Region A (V-direction).....................................................21
Figure 16. Deposition Fraction in Region A (P-direction) .....................................................22
Figure 17. Deposition Fraction in Region C (V-direction).....................................................23
Figure 18. Deposition Fraction in Region C (P-direction)......................................................23
Figure 19. Deposition Fraction in Region A (P-direction). ....................................................25
Figure 20. General particle deposition pattern for horizontal set-up ......................................26
Figure 21. Bifurcation tube vertical orientation set-up with enlarged deposition images ......26
Figure 22. Deposition Fraction in Region A...........................................................................27
Figure 23. Deposition Fraction in Region C (P-direction)......................................................28
Figure 24. General particle deposition pattern for vertical set-up ..........................................28

6. v
List of abbreviations
Abbreviation/Symbol Meaning
d - diameter of the dust particle
D - diameter of the pipeline
g - the gravitational constant
kp - transmission loss caused by deposited particle layer
ks - transmission loss caused by particles suspended in the air
kw - transmission loss caused by glass walls
Mp - mass of particle
P - equilibrium pressure of nitrogen under s.t.p.
P0 - saturated pressure of nitrogen
p(t) - particle deposition fraction at a given time
𝜌f - density of particle
r̂ - average radius of a single particle
rarea - equivalent particle radii based on area
req - Averaged equivalent particle radii
ri - distance between the center of the particle to its edge
Stk - stokes number defined as ρDg
2/9μD
V - total volume of nitrogen adsorbed
Vm - volume of nitrogen adsorbed by a single layer

7. vi
Abstract
Particle deposition in the human respiratory tract is a crucial study to quantify the impacts of
inhalable dust particles and access the effectiveness of drug aerosols delivery. Various studies
had been conducted on the deposition patterns of spherical and non-interactive micro- and
nanoparticles. This study focuses on industrial-generated particles, from incineration and
gasification, which are irregular in shape and may fracture into smaller particles upon
impaction. The deposition patterns of the 5 fly ash samples provided by Sembcorp Industries
Ltd. are investigated in a single bifurcation tube under oscillatory flow at 3 different sets of
simulation conditions. A Class II laser paired with a photodiode is used to evaluate the particles
deposition fraction in the various regions of the bifurcation tube at two different orientations.
Although no analytical correlation is derived from this experiment, the results show that
gravitational settling is the major factor in deposition due to the size of the samples (2 to 9 μm).
The presence of hot spots caused by inertial impaction are identified at the branching edges
and the end of daughter.
It is also found that non-spherical (fibre-like) particles respond minimally to the effect of
increasing flow rate and the breathing interval has little effect on the deposition fractions for
the 5 samples.

8. 1
1. Introduction
Deposition patterns of aerosol particles are of special interests for application in assessing
health impacts of the inhaled particles (Martonen and Schroeter, 2003) and targeted drug
delivery for respiratory diseases (D.A. Edwards, 2002). Various theoretical studies had been
conducted by simulating the particle flow within a straight tube under typical length-to-
diameter ratios for both inhalation and exhalation flows (Balấshấzy et al., 1993a,b). Recent
numerical studies with highly accurate airways’ geometry produced with the aid of computed
tomography (CT) images by Choi et al. (2007) and Van Ertbruggen et al. (2005) had further
advanced the computational simulations.
Although experimental studies have evolved from using smoke tracers and hot-wire probes for
flow visualization (Schroter et al., 1969) to Laser Doppler Velocimetry (Tanaka et al., 1999)
and the number of branching (generations) had also increased drastically by Yeh and Schum
(1980) from a single bifurcation tube, researches on non-spherical particle depositions are rare.
It is established by Heyder et al. (1986) that deposition correlates strongly to the particle
diameter (for range from 0.005μm to 15μm), irregular shaped particles are often simply
characterised by their aerodynamic diameter to predict their deposition patterns. Most of the
current researches (Timsina et al., 1994 and Kleinstreuer et al., 2008) are focused on targeted
drug delivery in the respiratory system due to the high potential commercial values. Since
particles from both dry-powder and mist inhalers are spherical, formed either mechanically or
naturally, there is a void in experimental studies for non-ideal non-spherical particles which
are commonly found in industrial areas.
Kulkarni, Baron and Willeke (2011) defines dust as solid particles formed by crushing or other
mechanical action resulting in physical disintegration of a parent material. These particles have
irregular shapes and are generally larger than 0.5 µm. Smoke is defined as a solid or liquid
aerosol, produced by incomplete combustion or condensation of supersaturated vapor. Both
smoke and dust particles are the main cause of issues such as smog, ozone depletion and bad
air quality. These particles not only cause detrimental harm to the environment but can also
deposit in the human airways and cause serious health problems. As Singapore is a heavily-
industrialized countries with oil refineries and chemical plants near her shores coupled with
the frequent haze caused by slash-and-burn, this study aims to help quantify the damages due
to particle pollution.

9. 2
The main objective of this study is to fill the gap of imbalance between the advancement of
computational methods and experimental study on less ideal non-spherical dust particles. It has
the potential for further research to determine the impact of changing particle shape at high
humidity (as the condition of a human airway), deposition of fibrous particles and investigation
of the enhanced deposition by interception theory proposed by Stum and Hofmann (2009).
Since the particles are collected from industrial plants, the deposition results can also serve as
a basis for setting health guidelines and recommending personal respiratory protective
equipment for the on-site employees.
The project is divided into 3 main phases: (i) construction, (ii) particle characterization and (iii)
experimental simulation with their findings reported under the respective sections in the report.
The construction phase was conducted from September to October where the experimental set-
up was suggested and refined and the essential equipment (microfeeder, vacuum pump,
rotameter, laser, filters, pipe connections etc.) were purchased, serviced and constructed for the
proposed set-up. To ensure the applicability and reality of this research, 5 different particle
samples were obtained from process plants in Sembcorp Industries Ltd. with unknown
characteristics. Therefore particle characterization was done in early November to aid in an
attempt to correlate the deposition pattern with the particles’ properties. Finally, the last phase,
experimental simulation runs under various sets of conditions were performed from November
till December.

10. 3
2. Literature Review
2.1 The human respiratory system
It is crucial to develop realistic and accurate models for both numerical and experimental
studies. A human respiratory system is often divided into 3 major regions (ICRP, 1994): (i) the
extrathoracic (ET) region, from the nose to the trachea, (ii) the tracheobronchial region (TB),
from the trachea to the bronchi, and (iii) the alveolar region where gas exchange in the blood
stream occurs as shown in Figure 1.
Figure 1. Schematics of the human respiratory system. (ICRP, 1994)
The first general approach in modeling the TB and alveolar regions is based on the tidal volume
(the total volume inhaled for a single breath). Burrowes et al. (2008) has developed a
comprehensive algorithm relating the air volumes in the main and branching daughter tubes. It
is limited as it cannot provide the exact dimensions of the airways and serve to only verify the
models constructed with approach 2.

11. 4
With development of computer tomography (CT) and magnetic resonance imaging (MRI) (the
2nd approach), more human-specific models are made. However, these digitally measured
dimensions vary considerably from person to person (Breatnach et al., 1984). Therefore, it is
generally accepted to simplify the airways of the TB and alveolar regions as a system of
symmetrically branching tubes with decreasing diameter. Some identifies these branchings
using generation numbers with 0 starting at the trachea and increases at every split as proposed
by Raabe et al. (1976).
2.2 Transport Principles and Fluid Dynamics
The deposition and transport of particles in the airway can be attributed to 4 governing
principles: sedimentation, diffusion, impaction and interception.
The deposition of large inhaled particulates are mainly characterised by the pneumatic transport
principle where particles will travel at the same velocity as the air velocity profile in the
airways. The minimum velocity for the particles to be airborne is calculated by
𝑈 𝑚𝑖𝑛 = [
4𝑀 𝑝 ∙ 101440𝑑+1.96 ∙ 𝑔550𝑑+1.25 ∙ 𝐷550𝑑−0.75
𝜋𝜌𝑓
]
1
1100𝑑+3.5
Where,
Umin is the minimum air velocity for convective transport
Mp is the mass of inhaled particles
d is the particle diameter
g is the gravitational constant
D is the diameter of transport pipe
𝜌f is the diameter of turn table
Sedimentation mechanism states that as the air velocity decreases down the generations due to
pressure drop and branching, larger particles with higher Umin will start depositing in the
airways due to gravity. Since the experimental fly ashes are large (in the range of micrometers),
this is postulated to be the major factor in producing the deposition patterns observed.
Diffusion mechanism is mainly attributed to the random Brownian motion of suspended
particles via convective transport and is most effective for sub-micrometer (<0.5 μm) particles.
The particles used in this study are much larger with low diffusivity constant of less than 10-11
m2 s-1 which is proven to have little impact on the deposition patterns (Heyder et al., 1986).

12. 5
Deposition by impaction occurs frequently at branching edges and constrictions in the TB
region when particles with high momentum deviate from the curved or narrowed air pathways.
This is expected to be another dominating mechanism due to the size of the particles involved
in this study.
The major mechanisms and the researches that contributed to their findings are summarised
in Table 1 for reference.
Table 1. Summary of variousanalyticalmethods’mechanisms
Deposition Mechanisms ResearchReferences
Sedimentation Martonen (1982)
Wang (1975)
Diffusion Cohen and Asgharuan (1990)
Ingham (1984)
Martonen (1982)
Yu and Cohen (1994)
Impaction Cai and Yu (1988)
Kim et al. (1994)
Zhang et al. (1997)
Interception Stum and Hofmann (2009)
2.3 Total vs local depositions
Total deposition is defined as the difference in particle concentration between inhalation and
exhalation in a single breath. Local scale particle deposition refers to study on particle
deposition patterns by simulating the flow of a small specific region of the respiratory tract.
Many researches based on total deposition, such as the studies done by Kim and Jaques (2004),
Brand et al. (2000), Heyder et all. (1986), had been completed at different sets of conditions.
An accurate numerical model with high agreement to the experimental data had also been
developed. However, these results are unable to identify the exact locations of particle
deposition which is crucial for analysing the health impacts. Reactive particles deposited in the
lower alveolar region though minute is fatal to human. Therefore, this study chose to focus on
particle deposition at local scale.to devise the exact deposition location. Furthermore, the fluid
dynamic patterns and mathematical correlations from local scale study can be used to fine-tune
the total deposition models.
For observation of local scale deposition, the respiratory tract is assumed to be straight glass
tube which branches out symmetrically to daughter tubes and granddaughter tubes, commonly

13. 6
known as the symmetric deterministic lung model (Yeh and Schum, 1980 and Weibel, 1963)
Since only total tidal volume and breathing intervals can be measured accurately, in the field
of local scale deposition studies, models are often constructed from the trachea (generation 0)
to the bronchial airways as the flow in the first bifurcation tube (simulating the first split to the
2 main bronchial airways) will influences the subsequent flow patterns and it is impossible to
verify the expected flow rates when starting from lower respiratory region.
Various researches by Yeh and Schum (1980), Comer et al. (2000) and Gemci et al. (2008) had
studied multiple bifurcation tubes extensively and constructed complicated models with up to
28 generations and 3x108 airways. However, it is found by Kim and Fisher (1999) that there
seems to be only slight differences between the depositions of the daughter tubes and the
subsequent generations of granddaughter tubes so this paper decided to simulate the trachea
and the main bronchi using a single bifurcation tube.
2.4 Flow rates, orientation and other considerations
A detailed experimental and simulation study by Xu et al. (2009) using single bifurcation tube
with the novel stabilized laser-photodiode measurement technique adopted by this paper had
explored the effects of oscillatory flow on deposition pattern with varying breathing cycles and
flow rates. Besides the major findings, the result presented shows that there are insufficient
particles covering the entire length of the daughter tubes at most of the arbitrarily set flow rates
and intervals. This study seeks to improve the applicability and realisticity of the previous
research by (i) increasing the air flow rates to ensure sufficient particle coverage, (ii) setting
the air flow rates and breathing intervals to that of an adult per International Commission on
Radiological Protection (1994), (iii) adding vertical orientation of the bifurcation tube to
simulate human standing, and (iv) employing industry-produced non-spherical particles for
simulation runs.

14. 7
3. Apparatus, Equipment and Methods
3.1 Overview of Experimental Set-up
Due to short intervals between inhalations and exhalations (typically 2 to 4 seconds) and
mechanical limitations, two pumps are used in the experimental set-up to simulate a continuous
oscillatory flow in the human respiratory system. During inhalation, valves 1, 2 and 3 are
opened while valve 4 remains closed and the air is taken in via the green path indicated in
Figure 2. Inert air is supplied from a compressed nitrogen cylinder free of moisture while the
particle samples are fed from a microfeeder through the ejector. Valve 3 acts as a relief valve
for the vacuum pump. For exhalation, all valves are closed except valve 4 and the air is drawn
from the fume hood through the bifurcation tube into the atmosphere along the red path.
Figure 2. Illustration of Experimental Set-Up. Green: Inhalation path; Red: Exhalation path.
After reviewing its feasibility, this theoretical framework is constructed as shown in Figure 3.
There are 3 sets of experimental conditions to simulate a person at rest (low inhalation rate and
long breathing interval), working lying down (high inhalation rate and shorter breathing
interval) and working upright (change in orientation of the bifurcation tube). In this study, the
2 independent variables, inhalation rates and breathing intervals, are adjusted using the
rotameter (Figure 3. ⑤) and logic controller box (Figure 3. ⑨) respectively while the
orientation is varied with the aid of the supporting board and various clamps.

15. 8
Figure 3. ActualExperimentalSet-Up. ①~④ correspondsto the4 electronic valves. ⑤:rotameter;
⑥: microfeeder; ⑦: ejector; ⑧: bifurcation tube; ⑨: logic controller box.
3.2 Bifurcation Tube
It is extremely difficult to set up an accurate model of a lung due to complications caused by
various changing conditions within the human body. Therefore, this study only focuses on
observing the particle deposition pattern in the trachea to the 2 main bronchi airway which is
simplified to a single glass bifurcation tube branching out to 2 daughter tubes. The bifurcation
tube is measured to obtain the following dimension as shown in Figure 4 and summarized in
Table 2.
Figure 4. Bifurcation glass tube

16. 9
Table 2. Summary of VernierCalliper Measurements in centimetres
Mouth of
Tube
Parent Tube Tail of Tube Daughter
Tube
Inner Diameter/cm 1.800 3.200 1.000 2.000
Outer Diameter/cm 2.205 3.605 1.430 2.430
A typical human has a 9 cm long trachea with 1.65 cm in diameter and 2 main bronchus of 3.8
cm long with 1.2 cm in diameter (International Commission on Radiological Protection, 1994).
Although these average values are much smaller than that of the model, there has always been
large variations in the measurements reported in different literatures (Breatnach et al., 1984).
3.3 Microfeeder
In order to obtain constant and accurate feeding of particles into the system, a table microfeeder
(from Sankyo Piotech, Japan) is serviced and used. The microfeeder has 4 major components
for particle addition: the hopper gate coarse scraping unit, edge scraping unit and fine scraping
plate as shown in Figure 5. The height/gap of the hopper gate controls the amount of particles
to be released from the hopper onto the round turn table depending on its flowability. The
coarse scraping unit determines the height of the layer of the particles formed on the turn table.
In this experiment of relatively low flow rate, the edge scraping unit serves to remove the
disturbance of the particle at the edge giving more accurate calculation of discharge rate.
Finally, the fine scraping plate unloads the particles into the ejector.
The amount of particles fed can be varied by adjusting the speed of the turn table using the
speed setter panel (ranging from 0.0 to 10.0). Building from the fundaments of a single turn
table feeder, the following correlation is determined,
𝑟𝑎𝑡𝑒 = ( 𝐻𝑐 − 𝐻𝑓) ∙ 𝑛 ∙ 𝜋 ∙ 𝜌 𝑉 ∙ ( 𝑑 ∙ 𝐷 − 𝐷2) (Equation 1)
Where,
Hc is the distance between coarse scraping plate and turn table (arrow in Fig 4. ii)
Hf is the distance between fine scraping plate and turn table (arrow in Fig 4. iii)
n is the speed of turn table
ρv is an unique particle-related property (related to bulk density)
d is the diameter of turn table
D is the feed distance of fine scraping plate

17. 10
i ii
iii
Figure 5. Microfeeder. i) top view; ii) front view; iii) back view & full view in the center
The measurements from Equation 1 are taken and correlated at different RPMs to obtain a
general linear relationship for each sample depicted in Figure 6. These correlations are used to
determine the various ρv which is essential to calculate the total amount discharged in one cycle
in the later sections.
Speed
Knob
Power
Switch
0.5A
Fuse
Hopper
Gate
Fine Scraping
Plate
Coarse
Scraping
Unit
To Ejector

18. 11
Figure 6. Graph of Discharge Rate against Turn Table RPM
3.4 Ejector
In order to maintain a desired flow rate, a constant pressure gradient is created across the entire
system. The microfeeder however operates at atmospheric pressure and an additional particle
ejector (VRL series, Nihon Pisco) has to be installed to introduce particles from a low pressure
(LP) to a high pressure (HP). The ejector functions on the basis of Bernoulli’s Principle and
employs the HP motive to compress the LP suction and discharges the particle at an
intermediate pressure. The basic principle is illustrated in Figure 7.
Figure 7. i) Particle Ejector used for construction. ii) Schematic drawing of ejector principle.
0
20
40
60
80
100
0 2 4 6 8 10
DischargeRatecm3/min
Turn Table Speed
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5
i ii

19. 12
3.5 Logic Controller Box (LCB)
A logic controller box (Mitsubishi Al-10MR-A) is used to automate the whole process of
swinging between inhalation and exhalation at pre-set intervals to improve the accuracy and
reproducibility of the experiment. The LCB runs on 240V AC and is able to simultaneously
process 6 electrical input signals while producing 4 response output signals. The 4 outputs are
directly linked to the 4 electronic valves and numbered according to the illustration of
experimental set-up in Figure 2.
Figure 8. PLC interior view withall wires connected.Blackbox:AC PowerSourceInput;Red box:Input
Terminals; Blue box: Output Terminals
In order to fully automate the entire simulation and reduce the number of electrical inputs (from
4 for controlling each of the valves to just 1), a program using different built-in function blocks
is written.

20. 13
Figure 9. Extended Function Block Program
A single digital signal is introduced (through the red wire into the input terminal in Figure 8)
as the first function block. The signal enters the second function block (the flicker block) which
acts as a pulse train generating a rectangular wave function giving 3 outputs (001, 002, and
003). One of the independent variables, the breathing interval, is simulated by adjusting the
duration/period and number of repetitions in this function block. Since either valve 3 or 4 has
to remain open at any given time to prevent pressure built-up in the vacuum pump line, the
output signal from valve 3 (003) is fed into the 04 NT (NOT) function block. The NT function
block serves to invert all incoming signals, changing an “OFF” to “ON” and vice versa.
3.6 Usage of Laser for Measurement
Since the particles’ deposition pattern is easily unsettled due to the thinness of the film layer
formed, a stabilised laser (Class II, 530 ± 10nm) with a receiving sensor is used. The intensity
of laser through the bifurcation tube at different sampling points are measured by the power
meter. The extent of particle deposition/coverage on the bifurcation tube is reflected by the
transmission loss (reduction in intensity) of the laser beam through the bifurcation tubes.
Two major assumptions are made to simplify the particle deposition into the 2-dimensional
transmission loss model illustrated in Figure 10.
1. Since the aim of the measurement is to determine the density of particles, the particle
sizes are assumed to be negligible compared to the approach of the laser beam. In other

21. 14
words, the characteristic length of the particle should be much smaller than that of the
diameter of the incoming laser beam. This is to ensure that no single particle is able to
entirely absorb/deflect the incoming beam resulting in a recorded 100% deposition
when only 1 particle is deposited. Although the particles used are of non-uniform
distribution with some having sizes of up to 0.8 cm2, all samples are passed through a
0.5 mm mesh sieve to ensure the validity of this assumption.
2. The 2-dimensional planar simplification is sufficient to describe deposition in the 3-
dimensioanl bifurcation tube. For this assumption to hold true, the diameter of the
incoming laser beam has to be much smaller than that of the dimeter of the bifurcation
tube.
Figure 10. The 5 mediums affecting the laser intensity.
The transmission loss model suggested by Xu et al. (2009) works on the principle of intensity
losses of the laser after passing through various intervening mediums. The power intensity
losses are due to the two bifurcation tube glass walls (kW1 & kW2), the deposited particles on
the tube walls (kP1 & kP2) and particles suspended in the air within the bifurcated tube (kS) as
shown in Figure 10. Based on this model, the transmission loss is calculated by
𝐼 𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑 = (1 − 𝑘 𝑊1)(1− 𝑘 𝑊2)(1− 𝑘 𝑃1)(1 − 𝑘 𝑃2)(1− 𝑘 𝑆)∙ 𝐼𝑠𝑜𝑢𝑟𝑐𝑒 (Equation 2)
where Imeasured is the laser intensity recorded by the intensity sensor (Figure 10) and Isource is the
intensity of the laser beam source. 3 major assumptions are made to further simplify Equation
2 to 3:

22. 15
1. The ambient air outside the tube contains negligible amount of dust particles and is
unlikely to cause significant intensity loss. Both the laser and sensor are also placed as
close to the tube as possible during measurements to reduce the impact of such
disturbance.
2. Intensity loss due to the suspension of particles in the air within the tube (kS) is constant
and minor. After each run, pure nitrogen gas at very low flow rate (1L/min) is passed
through the tube to flush out excess suspended particles in the air stream to eliminate
the suspended particles.
3. Transmission losses by the glass walls (kW1 & kW2) are equal for a constant thickness,
material and cleanliness.
𝐼 𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑 ≈ (1 − 𝑘 𝑊)2(1 − 𝑘 𝑃1)(1− 𝑘 𝑃2) ∙ 𝐼𝑠𝑜𝑢𝑟𝑐𝑒 (Equation 3)
𝐼 𝑤𝑎𝑙𝑙 = (1 − 𝑘 𝑊)2 ∙ 𝐼𝑠𝑜𝑢𝑟𝑐𝑒 (Equation 4)
where Iwall is the intensity of the laser beam recorded by the power meter before the start of the
experiment when only the bifurcation tube glass walls’ (kW1 & kW2) mediums are present with
suspension layer (kS) negligible. Combining Equations 3 and 4, surface deposition fraction can
be correlated as follow
𝐷𝑒𝑝𝑜𝑠𝑖𝑡𝑖𝑜𝑛 𝐹𝑟𝑎𝑐𝑡𝑖𝑜𝑛 = 1 −
𝐼 𝑚 𝑒𝑎𝑠𝑢𝑟𝑒𝑑
𝐼 𝑤 𝑎𝑙𝑙
(Equation 5)
This equation is true for asymmetrical deposition coverage where significantly more particles
are deposited on one surface than the other (kP1 »kP2 or kP1 «kP2). For a symmetrical deposition
pattern (kP1 = kP2) as in the case of the last of the 3 sets of experimental conditions, Equation 5
is modified to
𝐷𝑒𝑝𝑜𝑠𝑖𝑡𝑖𝑜𝑛 𝐹𝑟𝑎𝑐𝑡𝑖𝑜𝑛 = 1 − √
𝐼 𝑚 𝑒𝑎𝑠𝑢𝑟𝑒𝑑
𝐼 𝑤 𝑎𝑙𝑙
(Equation 6)
3.7 Definition of Co-ordinates
Since the orientation of the bifurcation tube will be varied in this study (2 in horizontal position,
1 in vertical) to simulate lying down and working standing up, the usual 3 dimensional (x-y-z)
plane is inadequate to describe the measurement. Two new directions, V and P are defined for
ease of comparison for different run conditions. V direction is defined as the vertical position
measurement when the laser passes perpendicular to the plane of the Y-shaped bifurcation tube
while the P direction is when laser passes parallel to the plane of the bifurcation tube as
illustrated in Figure 11.

23. 16
Figure 11. Two directions of measurements. Light Green: V-direction; Dark Green: P-direction
4. Characterisation of Particle Samples
Since this study aims to advise practical respiratory health tips and analyse the effect of
common industrial fly ash particles on the human respiratory system, all of the 5 samples are
collected on site with unknown characteristics such as their sizes, distribution spread, surface
area and chemical compositions. Therefore, Scanning Electron Microscopy and Brunauer–
Emmett–Teller analysis are done to obtain raw data of these basic characteristics.
4.1 Scanning Electron Microscope (SEM)
Scanning Electron Microscope will strike the surface of the sample with a focused beam of
electrons and an additional sensor will pick up the secondary electrons produced by the
interaction between the beam and the sample. These signals will produce a grey-scale SEM
micrograph with particles shown as bright spots.
Each sample is first evenly spread on a conductive (carbon) double-sided tape and mounted on
their respective specimen stubs. Since imaging relies on the release of secondary electrons and
dust particles are electrical insulators, the particles are sputtered with a thin-layer of metal (Pd
& Pt) under low vacuum condition before analysis. All micrographs for the 5 samples at
different magnifications (x300, x600, x1500, x3500) are included in Appendix A.

24. 17
Figure 12. Particle samples under various SEM magnifications
From the selected images in Figure 12, the circularity of samples I, II, IV and V are determined
to be in the range of 1.000 – 0.874 and their equivalent radii (req) are averaged between
Equations 7 and 8.
rarea = √ 𝐴𝑟𝑒𝑎 ÷ 𝜋 (Equation 7)
I II
III IV
V

25. 18
r̂ =
1
n
∑ 𝑟𝑖
𝑛
𝑖=1
(Equation 8)
Where,
r̂ is the average radius of a single particle
n is the number of measurements taken at equally spaced angles from the line of
symmetry
ri is the distance between the center of particle and the edge at each angle
Each pixel in Figure 12 is matched to their corresponding scales and every particle is manually
outlined as illustrated in Figure 13. An image processing program (ImageJ) is used to count the
total number of pixels in each enclosed outline for calculation of equivalent radii using
Equations 7 & 8. Since sample III has a general low circularity, its characteristic length (longest
distance from edge to edge) is measured instead of req.
Figure 13. Outlines of sample ii with each outline numbered in red and sample iii outlined in cyan.

26. 19
Figure 14. Particles’ size distribution for samples i, iii, iv and v
The results are plotted in a histogram to determine each samples dominating radii shown in
Figure 14. Sample II is omitted from Figure 14 as it is measured on a different scale. The full
measurement data and respective histograms for all 5 particles are included in Appendices B
and D.
0
5
10
15
20
25
30
35
40
1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 7 8 9 10 11 12 13 14 15 16 >16
Numberofparticels
Diameter / μm
Sample i
Sample iii
Sample iv
Sample v

27. 20
4.2 Brunauer–Emmett–Teller (BET) Machine
Particle size contributes significantly to the flow patterns developed in the airways and
determines how deep a particle is transported into the airway but its surface area is postulated
to have an impact on how much is deposited in the airway as larger surface area may result in
formation of more van der Waals bonds (DelRio et al., 2005).
The BET Machine (based on the BET theory) assumes that inert gas molecules will adsorb
onto particle surfaces forming infinite layers. The Langmuir Theory is applied to each layer for
the following BET correlation (S. Brunauer et al., 1938):
𝑝
𝑣(𝑝0 − 𝑝)
=
𝑐 − 1
𝑣 𝑚 𝑐
𝑝
𝑝0
+
1
𝑣 𝑚 𝑐
(Equation 9)
Where,
p is the equilibrium pressure of nitrogen
p0 is the saturated pressure of nitrogen
v is the total volume of nitrogen adsorbed
vm is the volume of nitrogen adsorbed by a single layer
c is the BET constant related to the enthalpy of adsorption
The data are plotted to determine vm which is used to calculate the specific surface area.
The results from SEM and BET machine are summarised in Table 3.
Table 3. Particle Characteristics
Sample
Surface Area
(m2/g)
Pore Diameter
(Å)
Characteristic Length
(μm)
Type
I 11.904 - 3.5 Mixed
II 0.001 - 0.5 Spherical
III 84.861 12.016 3.0 Fibres
IV 0.225 - 4.0 and 9.0 Isometric
V 13.956 9.407 2.0 Isometric

28. 21
5. Results and Discussion
In this study, the 5 samples were run for 5 minutes at 3 different conditions with the flow rates
varying from 10 to 25 L/min and breathing interval from 4 to 2 seconds. These conditions
correspond to a person at rest and doing light activities (ICRP, 1994). The orientation of the
bifurcation tube corresponds to the posture the human is taking.
Since the flow might not be fully developed in Region B (Figure 4) due to the split to the
daughter tubes, laser measurements were only made in Regions A (the main tube) and C
(branching daughter tubes) in Figure 4. An intensity measurement was taken every 0.3 cm (52
data points in Region A & 46 in Region C) to ensure a good coverage to develop an accurate
deposition pattern.
5.1 Human at rest (Flow Rate: 10 L/min, Interval: 4 seconds)
Gravitational settling and initial impaction might be the dominating factors for deposition as it
was observed that a significant amount of particles are deposited on the bottom surfaces in both
Regions A and C. Since asymmetrical deposition coverages were observed, Equation 5 was
used to normalise the laser intensity giving the deposition fraction Figures 14 to 17. The raw
experimental data was recorded and attached as Appendix D Deposition Measurements.
Figure 15. Deposition Fraction in Region A (V-direction)
Two general particle deposition trends were observed in Region A (the main tube): a gradually
increasing particle coverage for Samples 3 and 5; an U-shaped trend with a decreasing
deposition which flattens in the middle before increasing to maximum coverage nearing the
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
90.0%
100.0%
1 3 5 7 9 11 13 15 17 19 21 23 25
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5

29. 22
end of Region A as reflected by Samples 1, 2 and 4. The U-shape trend is supported by the
theory of Laryngeal jet (Zhang et al., 1997) and the effect of inertial impaction as presented by
Martonen (1993). The particles flowed into the bifurcation tube in the form of a Laryngeal jet
where the center velocity could be up to 3 times of the mean velocity. This velocity difference
caused a flow recirculation resulting in backflow and deposition at the entrance of the airway
model thus a higher coverage observed in Figure 15. The effect of Laryngeal jet seemed to be
more significant with spherical particles (Samples 1, 2 and 4) while Samples 3 and 5 were
carried in the central main flow.
Results of inertial impaction were observed in all the simulations evident in the peaks (hot
spots) at the end of Region A. The particle trajectory deviated from the curved air pathway in
Region B and made significant deposition at the split with its effects overflowing to end of
Region A and start of Region C. It is suggested by Chan et al. (1980) that the deposition pattern
could be calculated empirically using Equation 10.
𝑝( 𝑡) = 2.536 ∙ 𝑆𝑡𝑘1.231
(Equation 10)
where Stk is defined as ρDg
2/9μD. Due to limitations of measurements and lack of accurate
particle characteristics, the mathematical model was unable to be verified. However, the
impacts of these 2 theories were clearly evident in Figure 16 where measurements were taken
in the P-direction which eliminated particles deposition by gravitational settling.
Figure 16. Deposition Fraction in Region A (P-direction)
0.0%
5.0%
10.0%
15.0%
20.0%
25.0%
30.0%
35.0%
40.0%
45.0%
50.0%
1 3 5 7 9 11 13 15 17 19 21 23 25
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5

30. 23
Figure 17. Deposition Fraction in Region C (V-direction)
The general pattern for deposition in Region C (the daughter tubes) was a downward trend with
end peaks for samples 1 and 5. The peaks observed at the start and occasionally end of Region
C were attributed to the inertial impaction theory. The first peaks were due to overflow from
unstable Region B as observed in the study by Balấshấzy et al. (1999) while the end peaks were
caused by a gradual reduction in the radii of the airways. Two hypotheses were proposed to
explain the general downward trends: 1. reduction in the flow rates and 2. decreased quantity
of particles in the airstream. Due to branching which resulted in reduction of flow rate, the
heavy and large particle samples were not transported deeper into the bifurcation tube. The
amount of particles that could deposit might be minute in the beginning and minimum while
reaching the end of Region C. The 2nd hypothesis was supported by Figure 18 while measuring
particle coverage in the P-direction when all samples showed extremely low deposition.
Figure 18. Deposition Fraction in Region C (P-direction)
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
90.0%
100.0%
1 3 5 7 9 11 13 15 17 19 21 23
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5
0.0%
1.0%
2.0%
3.0%
4.0%
5.0%
1 3 5 7 9 11 13 15 17 19 21 23
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5

31. 24
5.2 Working laying down (Flow Rate: 25 L/min, Interval: 2 seconds)
In order to determine the major contributor of the 2 hypotheses, the bifurcation tube was kept
in the same horizontal orientation while increasing the flow rate of air to simulate a technician
at work lying down below the electrostatic precipitator.
It is postulated in hypothesis 1 that the flow rates were insufficient to form developed laminar
flow and majority of the particles were trapped in the bifurcation tube instead of being carried
by the oscillatory flow. Therefore the weight of the bifurcation tube was measured and recorded
in Table 4 before and after each run to validate this hypothesis. The tare weight of the
bifurcation tube was measured to be 89.9351g. Total weight of ejected particles in a run was
calculated using Equation 1 and the correlation in Figure 6. Total weight of particle deposited
is the difference between the gross and tare weight of the tube. The high range of percentage
deposition (>90%) calculated in Table 4 supports hypothesis 1 that the low flow rates were
insufficient to transport the majority of the particles.
Table 4. Summary of weighing measurementand totalpercentagedeposition
Gross Weight (g) Particle Ejected (g) Particle Deposited (g)
Percentage
Trapped
Sample 1 93.9027 4.3829 3.9676 90.52%
Sample 2 92.8671 3.1518 2.9320 93.03%
Sample 3 94.3390 4.5642 4.4039 96.49%
Sample 4 93.7392 4.0270 3.8041 94.46%
Sample 5 93.6632 3.8434 3.7281 97.00%
The normalised laser intensities for the 2nd set of conditions in Region A (the main parent tube)
were plotted as dashed lines with deposition fraction observed for the 1st set of conditions as
solid lines on Figure 19. It was observed that the 2nd set of data followed similar trends as that
of the 1st with the exception of Sample 4. The deposition fractions of the 2nd set of runs were
lower than the previous runs for measurement points 1 to 21 (which corresponds to the position
at the beginning and middle portion of the main tube) and the pattern reverses near the end
where more particles were deposited for runs done with the 2nd condition. At higher flow rates,
particles were carried further into the respiratory tract giving lesser deposition at the beginning.
The inertial of airborne particles were greater at higher flow rates and more were expected to
deviate and deposit at the branching hot spots in Region B. These observations are consistent

32. 25
with the 3 major deposition principles identified earlier, namely gravitational settling,
Laryngeal jet and inertial impaction.
Figure 19. Deposition Fraction in Region A (P-direction). Solid lines: Run 1 (at rest condition); Dashed
lines: Run 2 (at working condition).
The deviation in deposition coverage trend for Sample 4 might be due to a longer effect of the
initial Laryngeal jet resulting in a “lag” in reflecting the low deposition region in 1st condition.
Before the Laryngeal jet effects wore off, particles started depositing by inertial impaction and
the low deposition region was overlapped by both effects. It is also interesting to note that at
an increased flow rate, deposition pattern for Sample 3 remained relatively constant unlike the
other more spherical samples.
Despite the minor differences, runs at both conditions resulted in a similar deposition pattern
as illustrated in Figure 20 with hot spots at the branching edge and triangular deposition at the
end of Region C (the daughter tubes). All deposition images are attached as Appendix C
Deposition Pictures.
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
90.0%
100.0%
1 3 5 7 9 11 13 15 17 19 21 23 25
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5

33. 26
Figure 20. General particle deposition pattern for horizontal set-up
5.3 Working upright (Flow Rate: 25 L/min, Interval: 2 seconds)
Under conditions 1 and 2, the gravitational settling is the dominating effect on particle
deposition as seen in the asymmetrical coverage of top and bottom surfaces of main and
daughter tubes and an overall deposition reduction after increasing the flow rate. Technicians
working in the plant however are most likely to breath in fly ashes suspended in the air.
Furthermore, large particles governed by gravitational settling can be filtered by nostrils and
masks. Therefore, in this last set of conditions, flow rate and breathing interval are kept constant
while the bifurcation tube is fixed upright to reduce the particles deposited by gravitational
settling and simulate a person standing upright.
Figure 21. Bifurcation tube vertical orientation set-up with enlarged deposition images

34. 27
It was observed that the deposition fraction reduced significantly (down to 11% from 90%) and
the density of particles in Figure 21 was minute compared to Figure 10 and the other images
taken for horizontal set-up in Appendix C. The depositions were more balanced and
symmetrical (kP1 = kP2) around the walls of the tube for the vertical set-up and Equation 6 was
used to obtain the deposition fraction graph in Figure 22.
Figure 22. Deposition Fraction in Region A. Thick lines: P-direction; Thin lines: V-direction
There is a decreasing deposition trend for all samples with Samples 1, 2, 3 and 5 reaching 0%
deposition fraction before the end of region A. This observation supports hypothesis 2 which
postulates that there is insufficient deposit-able particles in the air stream and a majority of the
particles in all samples are gravitational settling controlled.
0.0%
2.0%
4.0%
6.0%
8.0%
10.0%
12.0%
1 3 5 7 9 11 13 15 17 19 21 23 25
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5

35. 28
Figure 23. Deposition Fraction in Region C (P-direction)
Figure 23, the plot for deposition fraction in Region C (the daughter tube) further confirms the
hypothesis and eliminates the possibility of particles not carried to the end of the bifurcation
tube. The sudden peaks observed indicates that the particles had been spread throughout the
tube and the heavy density of deposition (up to 100%) is due to gravitational settling of the
large particles within each sample. Similar to the horizontal runs, hot spots are detected at the
branching edge and the end of Region C.
Figure 24. General particle deposition pattern for vertical set-up
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
90.0%
100.0%
1 3 5 7 9 11 13 15 17 19 21 23
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5

36. 29
Plot for deposition fraction in Region C (V-direction) is omitted here as the deposition fractions
are near 0 and no useful conclusion can be drawn. All raw experimental measurements and
graphs are recorded in Appendix D Deposition Measurements.
6. Current Problems and Future Directions
The 3 major problems that limits the application of the experimental model in this study are (i)
the reality of unpredictability of the physiological factors in the human respiratory system to
construct the tube, (ii) the profile of inhalable particles suspended in the atmosphere and (iii)
practicality of application of analytical equations for the unstable oscillatory flow pattern.
The bronchial airways are simplified to straight, rigid and symmetrical glass tubes for
experimentation. The actual human airways are more complicated with unknown humidity,
uneven inner wall surfaces, asymmetrical branching and changing airways’ radii during
inhalation and exhalation. The breathing interval, single breath intake and lung capacity are
made realistic as determined by various pulmonary tests and correlation to the human’s height
and age (ICRP, 1994). These parameters however also vary drastically from person to person
resulting in large deviations in the observed deposition patterns (Hofmann et al., 2006).
Furthermore, the dimensions of the bifurcation tube are scaled up based on the functional
residual capacity but it can only accurately account for volumetric flow rather than providing
an exact structural model. Despite the simplifications, this experimental study is still useful as
a basis for understanding complex airways with multiple generations.
In this study, particles were ejected directly into the airstream feeding into the bifurcation tube
ending in the fume hood after passing through the filters as shown in Figure 1. Most particles
will pass through the bifurcation tube once before being trapped by the filters. In reality, only
light particles suspended in the air will be inhaled after being filtered by the nostrils and non-
deposited particles entering into the lower respiratory zone could be exhaled. Although a mesh
sieve was used to simulate filtering by the nose, a considerable amount of large particles still
entered into the airstream. A suspension chamber can be added before the bifurcation tube to
allow natural settling and suspension of particles before being inhaled into the bifurcation tube.
Another chamber can be added after the bifurcation tube to allow particles to be exhaled and
“re-deposited”.
Current depositions are predicted by simplified numerical simulations of spherical particle flow
in straight tubes and no complete analytical equations for bronchial airways for non-spherical
particles are available. Partial correlations such as inertial impaction for oscillatory flow

37. 30
suggested by Vinchurkar et al. (2009) and inhalation deposition for nanoparticles by Weibel
(1963) are insufficient to describe the entire airway depositions. With more sets of conditions
at different orientations of the bifurcation tube, there is potential for this set-up to formulate an
analytical correlation for deposition with the particles sphericity, surface area and aerodynamic
diameter.
Finally, after obtaining the analytical equations and the locations of deposition area, the
chemical compositions of the 5 samples should be analysed to access the health impact of these
chemicals at the specific areas.
7. Conclusion
Deposition fractions of industrial fly ashes has been determined experimentally in a single
bifurcation tube under oscillatory flow at 3 different sets of conditions. All 3 results have shown
that (i) gravitational settling is the major factor in deposition due to the size of the samples (2
μm to 9 μm), (ii) hot spots caused by inertial impaction are observed at the branching edges
and the end of daughter tubes (where there is a sudden decrease in flow diameter) and (iii) the
turbulent jet-like flow resulted in high deposition at the mouth of main tube.
Non-spherical particles deviates from the proposed equations and respond minimally to the
effect of increasing flow rate while the deposition fraction for more circular particles decreased
with increasing inhalation rate. The breathing interval appears to have no effect on the
deposition fractions.

38. 31
8. References
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Inspiratory flow. Journal of Aerosol Science, 24(6), 745-772.
Balásházy, I., & Hofmann, W. (1993). Particle deposition in airway bifurcations–II.
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Balấshấzy, I., Hofmann, W., & Heistracher, T. (1999). Computation of local enhancement
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Aerosol Science, 30, 185–203.
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the Royal Society of London A: Mathematical, Physical and Engineering
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Brunauer, Stephen; Emmett, P. H.; Teller, Edward (1938). "Adsorption of Gases in
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Choi, L. T., Tu, J. Y., Li, H. F., & Thien, F. (2007). Flow and particle deposition patterns in a
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Xu, Q., Leong, F. Y., & Wang, C. H. (2009). Transport and deposition of inertial aerosols in
bifurcated tubes under oscillatory flow. Chemical Engineering Science, 64(5), 830-846.
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41. 34
9. Appendices
9.1 Appendix A SEM micrographs
Figure A1 Particle I at different magnification
Figure A2 Particle II at different magnification

42. 35
Figure A3 Particle III at different magnification
Figure A4 Particle IV at different magnification

43. 36
Figure A5 Particle V at different magnification

44. 37
9.2 Appendix B Histograms of Particle Size Distributions
0
5
10
15
20
25
30
1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 10 11 12 13 14 >14
Numberofparticels
Diameter/ μm
Sample I
0
50
100
150
200
250
0.3
0.4
0.5
0.7
0.9
1.1
1.3
1.5
1.7
1.9
2.1
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
8
8.5
>9
Numberofparticels
Diameter/ μm
Sample II

45. 38
0
5
10
15
20
25
30
35
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
Numberofparticels
Length/ μm
Sample III
0
5
10
15
20
25
30
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 >23
Numberofparticels
Diameter/ μm
Sample IV
0
5
10
15
20
25
30
35
40
1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 7 8 9 10 11 12 13 14 15 16 >16
Numberofparticels
Diameter/ μm
Sample V

46. 39
9.3 Appendix C Deposition Patterns
Figure C1 Particle I Deposition
Figure C2 Particle II Deposition

47. 40
Figure C3 Particle III Deposition
Figure C4 Particle IV Deposition

48. 41
Figure C5 Particle V Deposition

49. 42
9.4 Appendix D Deposition Measurements
For all raw data, please refertoattachedfile orvisit https://goo.gl/xj0MGN.
9.5 Appendix E Particles Pixel Area
For all raw data, please refertoattachedfilesorvisit https://goo.gl/xj0MGN.
9.6 Appendix F PLC User Manual
Please refertohttps://goo.gl/xj0MGN.
0.0%
0.1%
0.2%
0.3%
0.4%
0.5%
0.6%
0.7%
0.8%
0.9%
1 3 5 7 9 11 13 15 17 19 21 23
Particle Coverage(Daughter TubeV-direction)
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5