ArticlePDF Available

An Investigation Into The Comparisons Of Exhaust Emissions Through Catalytic Converters Installed On A Kia Sportage Lx (Exhaust System)

Authors:
  • Tamale Technical University (Faculty of Engineering)

Abstract and Figures

This paper presents a study on the comparisons of the HC and CO emission levels on exhaust gases that expels through an existing home used (imported) car converter, a refurbished catalytic converter with a new honeycomb. The performance of a home used catalytic converter, refurb damaged catalytic converters by replacing the worn-out catalyst elements with imported ceramic honeycomb catalysts and compare the performance of the used catalytic converter to that of refurbished and two other locally developed converter of a Kia Sportage LX exhaust system were studied. The experimental results indicated that the refurbished catalytic converter with welded test and eco-liquid wash, produced lower emission than the home used, locally developed converter 1 (Suame Magazine) and locally developed converter 2 (Abossey Okai). For the locally made ones, the welded part of the case was not uniform therefore creating space for the exhaust gas to escape without proper filtration. The result also indicated that HC emission of 60.0 was recorded for the refurbished converter at an initial speed of 10.0 km/hr which is relatively lower than the HC emission recorded for the home used (65.8 ppm) catalytic converter. In addition, the refurbished type achieves a significant emission reduction of 5.8 when compared with the other types. The CO emission, the refurbished type had a reduction of 0.01% when compare with the home-used converter at varying speeds. Furthermore, the maximum test speed of 60 km/hr both the home-used and refurbished converters recorded the highest amount of (70.9 ppm, 63 ppm) and (2.52 % Vol, 2.42 %Vol) from the engine exhaust respectively. The refurbished converter yielded about 3.41% reduction in HC emission and 7.92 % CO emission which is better as compared to the Locally Developed converter 1 (Magazine). Again, the refurbished converter attained 4.39% reduction in HC emission when compared to the Locally Developed converter 2 (Abossey Okai) at idling speed.
Content may be subject to copyright.
International Journal of Scientific and Research Publications, Volume 10, Issue 3, March 2020 96
ISSN 2250-3153
http://dx.doi.org/10.29322/IJSRP.10.03.2020.p9908 www.ijsrp.org
An Investigation Into The Comparisons Of Exhaust
Emissions Through Catalytic Converters Installed On A
Kia Sportage Lx (Exhaust System)
Isaac Tekper1, Joseph Kwame Lewballah1, James Kwasi Quaisie3, Fred Joseph Komla Adzabe1, Emmanuel
Yeboah Osei1, Emmanuel Asamoah3, Philip Baidoo2, Andrews Danquah1
1Dept. of Mechanical Engineering, Kumasi Technical University, Kumasi, 00233, Ghana
2Faculty of Technology, University of Education Winneba, Kumasi, 00233, Ghana
3School of Mechanical Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China
DOI: 10.29322/IJSRP.10.03.2020.p9908
http://dx.doi.org/10.29322/IJSRP.10.03.2020.p9908
Abstract- This paper presents a study on the comparisons of the
HC and CO emission levels on exhaust gases that expels through
an existing home used (imported) car converter, a refurbished
catalytic converter with a new honeycomb. The performance of a
home used catalytic converter, refurb damaged catalytic
converters by replacing the worn-out catalyst elements with
imported ceramic honeycomb catalysts and compare the
performance of the used catalytic converter to that of refurbished
and two other locally developed converter of a Kia Sportage LX
exhaust system were studied. The experimental results indicated
that the refurbished catalytic converter with welded test and eco-
liquid wash, produced lower emission than the home used, locally
developed converter 1 (Suame Magazine) and locally developed
converter 2 (Abossey Okai). For the locally made ones, the welded
part of the case was not uniform therefore creating space for the
exhaust gas to escape without proper filtration. The result also
indicated that HC emission of 60.0 𝑝𝑝𝑚 was recorded for the
refurbished converter at an initial speed of 10.0 km/hr which is
relatively lower than the HC emission recorded for the home used
(65.8 ppm) catalytic converter. In addition, the refurbished type
achieves a significant 𝐻𝐶 emission reduction of 5.8 𝑝𝑝𝑚 when
compared with the other types. The CO emission, the refurbished
type had a reduction of 0.01% 𝑉𝑜𝑙 when compare with the home-
used converter at varying speeds. Furthermore, the maximum test
speed of 60 km/hr both the home-used and refurbished converters
recorded the highest amount of 𝐻𝐶 (70.9 ppm, 63 ppm) and 𝐶𝑂
(2.52 % Vol, 2.42 %Vol) from the engine exhaust respectively.
The refurbished converter yielded about 3.41% reduction in HC
emission and 7.92 % CO emission which is better as compared to
the Locally Developed converter 1 (Magazine). Again, the
refurbished converter attained 4.39% reduction in HC emission
when compared to the Locally Developed converter 2 (Abossey
Okai) at idling speed.
Index Terms- hydrocarbon, carbon monoxide, refurbished,
converters, catalyst.
I. INTRODUCTION
n a diesel engine, the engine condition is different from spark-
ignition engines, because power is directly controlled by the
fuel supply, not by controlling the air supply [1]. So when running
at low power, there is enough oxygen present to burn the fuel, and
diesel engines only create a large amount of carbon monoxide
when running under load. Diesel exhaust has been found to
contain many toxic air contaminants [2]. Lean-burning properties
of diesel engine combined with a high temperature and pressure of
the combustion process result in significant production of nitrogen
oxides and provide a unique challenge in the reduction of these
compounds [3, 4].
1.1 Catalytic converter
A catalytic converter (colloquially, '' cat ' or ''catcon ") is a
device used to reduce the toxicity of emissions from an internal
combustion engine. A catalytic converter provides an environment
for a chemical reaction wherein toxic combustion by-products are
converted to less toxic substances (Fig. 1).
Fig. 1. Three-way Catalytic convertor.
Since their inception, the car has been largely supported by
the internal combustion engine. Related to the engine combustion
process is responsible for releasing hazardous emissions including
carbon monoxide (CO), unburned hydrocarbons (HC) and
nitrogen oxides (NOx), which has a severe negative effect on
humans and the environment. This has led to the development of
I
International Journal of Scientific and Research Publications, Volume 10, Issue 3, March 2020 97
ISSN 2250-3153
http://dx.doi.org/10.29322/IJSRP.10.03.2020.p9908 www.ijsrp.org
exhaust emission control systems to treat and convert them into
less harmful products called catalytic converter [5, 6]. In three
decades, automobile manufacturers recognize the need to treat the
product of the combustion process that occurs in the internal
combustion engine [7]. The initial solution to this challenge is the
use of catalytic converter pellets. Pellets are spherical particles
with a diameter ranging from 2.5 mm to 5 mm and are made of
gamma-alumina. Pellets enclosed in a steel shell to form a
catalytic converter and laden with precious metals and stabilizers
for the treatment of exhaust emissions. The catalytic converter
technology has many drawbacks. Due to the design of catalytic
converter pellets of this, a large pressure drop occurs across a
converter that directly affects the performance of the engine. In
addition, a higher risk of losing catalyst for wear particles [8, 9].
Losses encourage scientists and engineers to develop a monolithic
catalytic converter found in today's vehicles. Monolith substrates
are the main components of the discharge line after the processing
systems found in today's cars. They provide superior performance
compared with other types of support pellets. monolith substrate
typically characterized by cell density and wall thickness channel
them. Because the total surface area of the channels and a small
thermal mass of the substrate, the heat transfer is greatly improved,
which increases the conversion efficiency indicates improved
thermal performance [10]. The thermal performance of the
catalytic converter is usually measured in terms of the time
required for the catalytic converter to reach the light-off
temperature. The '' temperature 'light-off was calculated as the
temperature at which the conversion efficiency of the pollutant
reaches 50% [11]. Cheng and coauthors suggested many
techniques for the mathematical model of the flow field in the
substrate ranging from a 1D model of unidirectional to a full and
comprehensive 3D model [12-14]. In their study, CFD
(Computational Fluid Dynamics) analysis was used to predict the
behavior of the flow, and thermal characteristics of the monolith
substrate conversion efficiency. In addition, Young and co-
researchers [15-17] developed a mathematical model of the
earliest to study the physical and chemical processes in catalytic
converters. Their model included the effects of heat and mass
transfer in laminar flow in the monolith and the monolith channels.
Many researchers investigate and steady state flow simulation
under conditions of reacting flows [18-20] and other researchers
investigating the flow steady-state non-reacted in a catalytic
converter [21, 22]. Transient flow simulation is also used by some
researchers to investigate the performance of catalytic converter
during the cold-start period including [23-25]. In addition, other
researchers studied only flow in the hydraulic behavior of the
monolithic substrate under cold flow conditions stable state [26,
27]. According to Shelef and co-authors [28, 29] reviewed the
catalytic converter system to control automobile emissions. Their
study covered the main principles and the performance of catalytic
converters. They discussed the catalytic converter durability and
performance of catalytic converters influence on the thermal
management of the engine. A more uniform flow distribution
increases conversion efficiency and durability of the catalytic
converter [11, 30-32]. This leads to less greenhouse gas emissions
(Green House Gas) [33, 34]. On the other hand, the study included,
Shuai and Wang [35], Chen and Schirmer [36] and Cho et al. [37]
focused on the effect of the monolith exhaust manifold design and
distribution properties on the flow and hydraulic performance of
the catalytic converter. Lai et al. [38] studied the effect of the
geometry of the exhaust manifold inflow distribution pipe bending
tends to distort the flow and increase the flow misdistribution.
They used 3D simulation incorporating robustness brick into the
simulation to obtain an accurate prediction. They concluded that
streams are becoming more evenly when the inlet pipe shorter in
length and smaller bending angle. In addition, they examined the
effects of nature brick concluded that the higher the flow
distribution more uniform brick resistance observed flow
distribution [23, 30, 33, 39]. Liu et al. [40] conducted an
experimental and numerical study on reverse flow catalytic
converters for natural gas / diesel dual engine. They concluded that
the CO and HC conversion efficiency improved for reverse flow
catalytic converters for low inlet temperature and light engine load
only when the initial temperature of the catalytic converter is quite
high. Many researchers have studied the effect of pressure drop in
the hydraulic performance of the catalytic converter [26, 27, 41,
42]. They examined the effects of inlet flow conditions, properties
and catalytic converter substrate geometry on the pressure
reduction utilizing a variety of modelling strategies. In addition,
the thermal behavior of the catalytic converter has been studied by
many researchers [11, 25, 43, 44]. The limits lowered the
feasibility study and the more feasible approach is required [45].
It can be concluded that the need for a new catalytic converter
technology has continued to grow in order to meet the more
stringent standards of global emissions of the vehicle and the
increasing demand for environmental protection and rising fuel
prices. In view of these, most Ghanaians vehicles are for both
commercial and private purpose as a means of transporting goods
and providing services. Apart from walking (65.6%), trotro
(16.0%) is the most popular means of transport to the market [46].
The percentage of used cars being patronized in Ghana is
significantly high because of relatively cheaper duty and
importation charges. Used vehicles imported into Ghana come
with old catalytic converters that might have exhausted their
lifespan. The life span of these catalytic converters cannot be
determined because of how they have been used on a particular
vehicle. Almost all the malfunction catalytic converters are
replaced with home used ones which are cut open and are usually
sold in the local market (spare parts dealers) such as Abossey
Okai, Accra [47, 48] or Suame Magazine, Kumasi [49, 50]. The
extent of damage of the ceramic honeycomb catalyst which is
widely used as catalyst support and as particulate, filters for
vehicular emission control in a used converter cannot be detected.
Most People with faulty catalytic converters on their vehicles are
forced to use home-made type converters of different brands
whose qualities cannot be guaranteed. They cut open and later
weld these parts without considering the design parameters such
as the accuracy of the angles formed within the converter and the
space between the catalyst and the inner housing.
The purpose of this work is to compare the HC and CO
emission levels on exhaust gases expelling through an existing
home used (imported) car converter, a refurbished catalytic
converter with a new honeycomb and two other locally developed
(purchased in local market) converters installed on a Kia Sportage
LX (2009 model) exhaust system. This study further goes on to
study the performance of a home used catalytic converter, refurb
damaged catalytic converters by replacing the worn-out catalyst
elements with imported (brand new) ceramic honeycomb catalysts
International Journal of Scientific and Research Publications, Volume 10, Issue 3, March 2020 98
ISSN 2250-3153
http://dx.doi.org/10.29322/IJSRP.10.03.2020.p9908 www.ijsrp.org
and also to compare the performance characteristics of the home
used catalytic converter of refurbished and two other locally
developed converter on Kia Sportage LX exhaust system.
II. MATERIALS AND METHODS
2.1 Design of catalytic converter
2.1.1 Fabrication
Assembly of all sub-components together with a catalyst
wash coat filled will make a new catalytic converter that is ready
for testing as shown in Fig. 2 and 3.
Fig. 2. Assembled Drawing of Catalytic Converter
Fig. 3. Detailed Drawing of Catalytic Converter
2.1.2 Assessment of the Selected Converter
The starting point of the conversion process is the selection
of an old catalytic converter to be converted (refurbished). In this
study, four (4) identical old catalytic converters of Kia Sportage
(performance characteristics) were obtained from the open market
(Abossey Okai and Suame Magazine). Out of these four (4), one
was selected for the refurbishment. Figure 4 shows various
Catalytic converters of Kia Sportage available in the local market.
Fig. 4. Four Old Catalytic Converters
The various converters were assessed and converter ‘A’ was
selected to enable the selection of appropriate honeycomb for this
work. The selection of converter “A” was based on the fact that its
exhaust manifold has the same dimensions as the control type.
Table 1 Physical Properties of All Four Catalytic Converters
No
Types
Cell density
(cells/in2)
Hydraulic
diameter(mm)
Washcoat
thickness
A
Home used
Car’ converter unit
400
1.14
25
B
Refurbished
400
1.14
25
C
Locally developed 1
(Suame)
400
1.14
25
D
Locally developed 2
(Abossey Okai)
400
1.14
25
Source: Kia Sportage LX Manual Book
The physical properties obtained in the analysis were used to
determine other parameters that cannot be obtained
experimentally such as geometric surface area, open frontal area
and cell pitch.
2.1.3 Cleaning of residuals in the converter
A flash cleaning is carried out to remove the residuals in the
converter with eco liquid. Eco-Liquid is water-based cleaning and
degreases liquid with excellent anti-corrosion properties for parts.
The converter was washed thoroughly with a high-pressure water
hose. Figure 5 shows the cleaning of the catalytic converter.
Fig. 5. Cleaning of residuals in the converter
2.1.4 Conversion of Selected Home Used Converter
International Journal of Scientific and Research Publications, Volume 10, Issue 3, March 2020 99
ISSN 2250-3153
http://dx.doi.org/10.29322/IJSRP.10.03.2020.p9908 www.ijsrp.org
To convert the selected home used converter to a refurbished
converter, the steel shell is cut open from the top using gas torch
of an electric arc welding machine and the honeycomb was
removed. The angles and length were all checked to avoid
distortion. The brand new imported honeycomb was placed inside
the seats. Both the inlet and outlet were also inspected to suit the
design of the converter. The system was then put together after
thorough checks on the converter to avoid any air space on the
walls before fabrication. Figure 3-5 shows the cutting of the
catalytic Converter (Refurbished) with an electrical Grinding
Machine.
2.1.5 Gas Welding Process Overview
Oxygen and acetylene together in a flame provided the heat
necessary to melt the metals. This combined with a neutral
welding atmosphere and suitable filler material is suitable for
heating and cutting purposes. Figure 6 shows a diagram of the Gas
welding process of the refurbished converter.
Fig. 6. Oxy-Acetylene Gas Welding of the Converter
2.2 Installation of the refurbished Catalytic Converter to Exhaust
Systems
The last stage of the preparatory process was to join the
various catalytic converters to the exhaust system of the Kia
Sportage Lx. This was done by directly bolting the refurbished
converter to the heads and lead down in the exhaust system with a
basic set of hand tools. These processes were repeated for all other
converters for the experimental studies. The diameters of the pipes
of all the converters were the same for conformity. Figure 3-7
shows the Installation of the Catalytic Converters bolted to the
Exhaust Systems of the Kia Sportage LX in the at DVLA-PVTS
at Dodowa.
Fig. 1. Installation of the refurbished Catalytic
Converters to Exhaust Systems
2.3 Exhaust Gas Analyzer
There are various types of gas analyzers with various
guidelines. They are equipped to evaluate various types of gas.
The gas analyzer is the ideal tool to investigate the types of
substances present in the sample gas. He acknowledged the
species and has the ability to give a good estimate of the number
of structures show a numerical or graphical. Depending on the
type of examination guidelines opt for gas, can be named both gas
chromatography, IR gas analyzer, thermal conductivity gas
analyzer, gas analyzer paramagnetic and electrochemical analysis,
orsat devices, gravimetric or methanometer gas analyzer. Figure
2-8 shows the smoke gas analyzer. Exhaust emission from the
engine was measured with an AVL five gas 444 gas analyzer (Fig.
8).
Fig. 8. AVL Gas Analyzer.
2.4 Experimental and Theoretical Formulation (Conceptual
framework)
To achieve the specific objectives of this study, a series of
experiments carried out at Kia Sportage LX. These can be grouped
into four main sections. The first part consists of experiments were
conducted to determine the HC and CO of the house used Kia
Sportage Catalytic Converter. The second part includes the
experiments carried out to study the general performance of the
type of refurbished with a new honeycomb and finally, the two
purchased locally (updated) converter from Suame Magazines and
Abossey Okai respectively. The experimental data would be based
on the HC and CO values of each converter. Figure 9 illustrated
the conceptual framework of the study.
Fig. 9. Conceptual framework of the study
2.5 Specifications of the Kia Sportage
The 2009 Kia Sportage is the ranking is based on its score in
2009 Affordable Compact Sports utility vehicle (SUV) category
and it is front-wheel drive. Sportage has a long list of standard
interior features. Sportage list of standard features is quite
impressive and includes a six-speaker audio system with USB
port, air conditioning and satellite radio. features available include
a navigation system, leather-wrapped steering wheel and remote
International Journal of Scientific and Research Publications, Volume 10, Issue 3, March 2020 100
ISSN 2250-3153
http://dx.doi.org/10.29322/IJSRP.10.03.2020.p9908 www.ijsrp.org
engine start. Table 3-2 shows some of the specs of the house used
2009 Kia Sportage LX model.
Table 2 Specifications of the Kia Sportage LX
Specifications of Kia spot age Lx
Car type
Sport utility vehicle
Transmission
Automatic
Engine type
Petrol
Number of Cylinders
Inline 4
Drive Train
Front-wheel Drive
III. RESULTS AND DISCUSSION
Tests were conducted to determine the effectiveness of
catalytic converters used Kia Sportage Lx house, refurbished with
brand new honeycomb and two other types of renewable locally
installed on a Kia Sportage-house exhaust system is used. The test
results of control tests (home-ex converter) compared with the
performance of three identical conversational converters and
discussion was made on the performance characteristics of the
type of converter tested. This section is divided into four main
parts as follows:
3.1 Performance Kia Sportage LX Converter Local Converter
Compared with three refurbished
This section presents results of experiments conducted to
study the performance characteristics of the catalytic converter
that already exist on the Kia Sportage, the converter refurbished
with brand new honeycomb and two converters purchased locally
in relation to the content of the emissions of hydrocarbons and
carbon monoxide them through the exhaust system of the Kia
Sportage LX, Table 4-1 presents the results of the test. Four major
tests performed on four types of converters. Of emission values,
the percentage reduction achieved in each case calculated and
presented as shown in Table 4-1.
Table 3 Readings of HC’s and CO’s values of the four converters and their percentage reductions
Result at idling speed
No
Converters type
Emissions
Hydrocarbons
(ppm)
HC Reduction
(%)
Carbon Monoxide
(% Vol)
CO Reduction
(%)
1
Home used
65.8
0
2.37
0
2
Refurbished
61.1
7.69
1.68
41.07
3
Locally made 1 (Suame
Magazine)
63.1
4.28
1.79
33.15
4
Locally made 2 (Abaosokai)
63.7
3.3
1.85
28.11
3.1.1 Emissions (idling)
Figure 10 shows emission values in the idling case for the
test involving the four converter types used for study as presented
in table 3. In Figure 10 it can be seen that the level of hydrocarbon
released by the refurbished converter is 61.1 ppm, which is
relatively lower compared with the other converters. The home
used converter registered the highest levels of HC emission with a
value of 65.8 ppm. Per the results depicted in figure 10, it can be
said that the refurbished converter performs much better than the
other samples tested. In comparison, the refurbished converter
released about 7.69 % of HC emissions less than the home-used
type. However, it can be observed that the emissions recorded for
all samples tested are much lower than the standard value of 200
ppm.
Fig. 10. Comparison of HC Values for types of
Converters
International Journal of Scientific and Research Publications, Volume 10, Issue 3, March 2020 101
ISSN 2250-3153
http://dx.doi.org/10.29322/IJSRP.10.03.2020.p9908 www.ijsrp.org
Figure 11 shows emission values in the idling case for the
test involving the four converter types used for study as presented
in table 3. According to figure 11, it can be observed that the
refurbished converter recorded the lowest CO emission levels of
1.68 % Vol followed by the locally developed type 1. The home
home-used type recorded the highest value of 2.37% Vol. in
comparison with the standard recommended value, however, it can
be seen that the CO emission values for all samples tested fall far
above the mark of 0.2 % Vol. CO.
Fig. 11. Comparison between of CO of Various
Converters
3.1.2 Emission Reduction
The refurbished converter achieved the highest emission
reduction of about 7.69% HC and 41.07 % CO in comparison with
the other samples tested. Thus, the refurbished converter can be
said to be the most effective sample in this regard.
3.2 HC and CO emissions with the Engine Speed
HC and CO emission measurements were also done at
varying speeds in order to determine the effect of speed on
emissions. For safety reasons, the speed of the vehicle for the test
was run from 10.0 𝑘𝑚/ℎ𝑟 to 60.0 𝑘𝑚/ℎ𝑟 at 5.0 𝑠𝑒𝑐𝑜𝑛𝑑𝑠
intervals for the entire period of 30 minutes. Table 4 shows
emission values of the converters types from four sets of tests
when the vehicle was run from an initial speed of 10.0 km/hr to 60
km/hr on rollers at DVLA - Ghana.
Table 4 Emissions recorded at varying speeds
Converter Types
Selected
converters
EMISSIONS
Home used
Refurbished
Locally made 1
(Suame Magazine)
Locally made 2
(Abaosokai)
Emission
Types
HC
(ppm)
Home
Used
CO (%
Vol)
Home
Used
HC (ppm)
Refurbish
ed
CO (%
Vol)
Refurbish
ed
HC
(ppm)
Locally
Develop
ed 1
CO (%
Vol)
Develop
ed 1
HC
(ppm)
Develop
ed 2
CO (%
Vol)
Develop
ed 2
Speed km/hr.
10
65.8
2.37
60
2.36
60
2.38
61
2.37
20
65.9
2.38
60.2
2.36
60.21
2.37
61.2
2.27
30
70.1
2.38
60.2
2.37
61.1
2.38
61.9
2.38
40
70.2
2.4
61
2.38
61.2
2.39
62.2
2.39
50
70.6
2.5
62
2.41
62.3
2.41
62.3
2.42
60
70.9
2.52
63
2.41
63.2
2.42
63.1
2.42
Av
Emissio
ns
35
68.91
6667
2.425
61.06667
2.3816667
61.335
2.391666
667
61.95
2.391833
333
3.2.1 Variations of HC Emissions versus Engine Speeds
Figure 12 shows a graph of 𝐻𝐶 emissions with respect to
engine speed. It can be observed that (see table 4-2) the HC
emissions increase with increasing speed. Results show that the
HC emission rises from 65.8 ppm at a speed of 10.0 km/hr to a
value of 70.9 ppm at a speed of 60.0 km/hr. The average speed
was 35.0 km/hr with a recorded average emission value of 70.8
ppm.
International Journal of Scientific and Research Publications, Volume 10, Issue 3, March 2020 102
ISSN 2250-3153
http://dx.doi.org/10.29322/IJSRP.10.03.2020.p9908 www.ijsrp.org
Fig. 12. Graph of HC emission vs Engine Speed
3.2.2 Variation of CO emissions with Engine Speed
Figure 13 shows that CO emission of the home-used
converter varies linearly with engine speed. As indicated in figure
13, it is observed that the CO emissions increase with increasing
engine speed. The results show that the CO emission rises from
2.37 %Vol at a speed of 10.0 km/hr to a value of 2.52 %Vol at a
speed of 60.0 km/hr. At an average speed of 35.0 km/hr the CO
emission recorded was 2.39 % Vol.
Fig.13. CO (% Vol) vs Speed (km/hr)
3.3 Emissions results of Home-used converter and Refurbished
converter
Figure 14 shows that the HC emitted from the refurbished
converter exhaust system at a speed of 10.0 km/hr was 60.0 𝑝𝑝𝑚
which is relatively lower than that of the home used (65.8 ppm)
catalytic converter. This implies that there is a significant
improvement in reduction (5.8 𝑝𝑝𝑚) of 𝐻𝐶 emission present in
the exhaust gas. Figure 4-5 indicates that, at the highest speed of
60 km/hr, HC emissions of the Home-used and refurbished
converters were 70.9 ppm and 63.0 ppm respectively. Figure 14
shows a graph of HC versus speed for home used and refurbished
converters.
Fig. 14. HC Emissions of Home Used Converter
versus Refurbished Converter
At the same time, there is a significant reduction of
0.01 % 𝑉𝑜𝑙 in the 𝐶𝑂 emission between the home-used converter
and the refurbished. Over the speed range of 10-60 km/hr, the CO
emission recorded for refurbished and home-used converters were
2.52% Vol and 2.41 %Vol respectively. In other words, the
refurbished catalytic converter was able to reduce the HC
emissions by 12.54% and CO emissions by 4.56%. Figure 15
shows a graph of CO versus speed for home used and refurbished
converters. It can be observed that as speed increases % Vol of CO
emission for refurbished converter increases from 2.36 to 2.41 %
Vol. whereas the CO emissions for the home-used type remains
fairly constant. It can also be observed that HC emission level of
the refurbished type remains constant with increasing speed
whereas that of the home-used converter varies between 60 and 63
ppm.
Fig. 15. CO Emissions of Home Used Converter
versus Refurbished Converter
3.4 Comparison of 𝑯𝑪 and 𝑪𝑶 Emissions of Refurbished and
Locally Developed Converters
3.4.1 Comparison of 𝑯𝑪 Emissions of refurbished and locally
developed Converters
International Journal of Scientific and Research Publications, Volume 10, Issue 3, March 2020 103
ISSN 2250-3153
http://dx.doi.org/10.29322/IJSRP.10.03.2020.p9908 www.ijsrp.org
By comparing the 𝐻𝐶emissions of the refurbished and
locally developed converters, it can be stated that the difference in
HC values are significantly high. The differences in HC emission
values were obtained from table 4. The refurbished converter had
an average HC emission of 61.067 ppm as compared to the
converters from Suame magazine (Locally Developed 1) and
Abossey Okai (Locally Developed 2) which had average HC
emission values of 61.335 ppm and 61.950 ppm at an average
speed of 35 km/hr respectively. According to figure 16, it can be
observed that the refurbished converter had the lowest HC
emissions making it the most effective among the three converters.
It can also be seen that the developed converter from Abossey
Okai had the highest HC emission. Considering idling condition
from table 4-1, the percentage reduction of the HC emissions of
the refurbished and the two locally developed converters were also
calculated. This gives the percentage emission reduction value of
the refurbished converter as 7.69 % whilst the Suame Magazine
and Abossey Okai converters recorded 4.28% and 3.3%
respectively. Again, there was a significant improvement in the
percentage reduction of HC emission when compared to the
Locally Developed converter bought from Abossey Okai. From
the percentage reductions, it can be observed that there was an
improvement in the HC emissions for the refurbished converter as
compared to the other converters when the vehicle was idling.
Fig. 16. Comparison of 𝑯𝑪 Emissions of refurbished
and locally developed Converters
3.4.2 Comparison of 𝑪𝑶 Emissions, refurbished and locally
developed Converters
Similarly, the CO emissions of the three converters were also
considered during the experiment. It was also observed that the
refurbished converter had a lower average CO emission of 2.381
%Vol as compared to the locally developed converter 1 (2.391
%Vol) and locally developed converter 2 (2.391 %Vol)
respectively. In figure 17, it can be observed that the refurbished
converter achieves a better performance with respect to CO
emissions since it recorded to the lowest value of 1.68 %Vol. for
the scenario involving idling speed. However, the values of CO
recorded for all samples were far higher than the recommended
value of 0.2 %Vol. Hence it is advised that a brand new
honeycomb should be considered since that works better with CO
emission and also have a longer lifespan.
Fig. 17. Comparison of 𝑪𝑶 Emissions of refurbished
and locally developed Converters
IV. CONCLUSIONS AND RECOMMENDATIONS
5.1 Conclusion
This study examined the catalytic converter performance of
HC and CO emission for home used Kia Sportage LX’s catalytic
converter, a refurbished type and the performance of two locally
developed types from the local market installed on the home used
Kia Sportage exhaust system.
From the results of the study, the following conclusions are made:
1. The refurbished catalytic converter with welded test and
eco-liquid wash, produced lower emission than the home
used, locally developed converter 1 (Suame Magazine)
and locally developed converter 2 (Abossey Okai). For
the locally made ones, the welded part of the case was not
uniform therefore creating space for the exhaust gas to
escape without proper filtration.
2. An HC emission of 60.0 𝑝𝑝𝑚 was recorded for the
refurbished converter at an initial speed of 10.0 km/hr
which is relatively lower than the HC emission recorded
for the home used (65.8 ppm) catalytic converter. Results
further show that the refurbished type achieves a
significant 𝐻𝐶 emission reduction of 5.8 𝑝𝑝𝑚 when
compared with the other types. For CO emission, the
refurbished type had a reduction of 0.01% 𝑉𝑜𝑙 when
compare with the home-used converter at varying speeds.
3. At the upper speed of 60.0 km/hr, both the home-used
and refurbished converter recorded the maximum HC
emission values of 70.9 ppm and 63.0 ppm respectively,
whereas the corresponding maximum CO emission
values recorded were 2.52 % Vol for the home used type
and 2.42 % Vol. for the refurbished type.
4. At the upper speed of 60.0 km/hr, the refurbished
converter reduces its HC emission by 12.54% and CO
emissions by 4.56 % compared with the home-used
converter. On the other hand, at the upper speed of 60.0
km/hr, local type 1 and local type 2 reduce HC emission
by 12.18 % and 12.36 % respectively whereas the
corresponding reduction values for CO emission was
4.13 % for both local types
International Journal of Scientific and Research Publications, Volume 10, Issue 3, March 2020 104
ISSN 2250-3153
http://dx.doi.org/10.29322/IJSRP.10.03.2020.p9908 www.ijsrp.org
5. At the maximum test speed of 60 km/hr both the home-
used and refurbished converters recorded the highest
amount of 𝐻𝐶 (70.9 ppm, 63 ppm) and 𝐶𝑂 (2.52 % Vol,
2.42 %Vol) from the engine exhaust respectively.
6. The refurbished converter yielded about 3.41% reduction
in HC emission and 7.92 % CO emission which is better
as compared to the Locally Developed converter 1
(Magazine). Again, the refurbished converter attained
4.39% reduction in HC emission when compared to the
Locally Developed converter 2 (Abossey Okai) at idling
speed.
5.2 Recommendations
In respect to the results obtained, the following recommendations
are made:
further work should be carried out to compare the
performance of the four converters for the recommended
maximum speed limit on the high way in Ghana (being
100km/hr)
In terms of HC performance, the refurbished type is
recommended since it produced the lowest HC
emissions, which falls far below the international
standard. However, all samples tested could not meet
international standards for CO emissions. Hence, it is
recommended that the DVLA should enforce existing
regulations by ensuring that all converters used on
registered vehicles should be brand new.
REFERENCES
[1] [1] S. Koutros, M. Kogevinas, M. C. Friesen, P. A. Stewart, D. Baris, M.
R. Karagas, et al., "Diesel exhaust and bladder cancer risk by pathologic stage
and grade subtypes," Environment International, vol. 135, p. 105346,
2020/02/01/ 2020.
[2] [2] J. M. Ferguson, S. Costello, H. Elser, A. M. Neophytou, S. Picciotto,
D. T. Silverman, et al., "Chronic obstructive pulmonary disease mortality:
The Diesel Exhaust in Miners Study (DEMS)," Environmental Research, vol.
180, p. 108876, 2020/01/01/ 2020.
[3] [3] A. Vembathu Rajesh, C. Mathalai Sundaram, V. Sivaganesan, B.
Nagarajan, and S. Harikishore, "Emission reduction techniques in CI engine
with catalytic converter," Materials Today: Proceedings, 2019/08/21/ 2019.
[4] [4] X. Wang, Y. Wang, Y. Bai, P. Wang, D. Wang, and F. Guo, "Effects of
2,5-dimethylfuran addition on morphology, nanostructure and oxidation
reactivity of diesel exhaust particles," Fuel, vol. 253, pp. 731-740,
2019/10/01/ 2019.
[5] [5] S. Chan and D. Hoang, "Heat transfer and chemical reactions in exhaust
system of a cold-start engine," International journal of heat and mass transfer,
vol. 42, pp. 4165-4183, 1999.
[6] [6] C. Bruno, P. Walsh, D. Santavicca, and F. Bracco, "High temperature
catalytic combustion of CO− O2− N2, Ar, He, CO2− H2O mixtures of
platinum," International Journal of Heat and Mass Transfer, vol. 26, pp.
1109-1120, 1983.
[7] [7] R. J. Farrauto and R. M. Heck, "Catalytic converters: state of the art and
perspectives," Catalysis Today, vol. 51, pp. 351-360, 1999.
[8] [8] C. Wassermayr, W. Brandstätter, and P. Prenninger, "An integrated
approach for the design of diesel engine exhaust systems to meet Euro 4 and
beyond emissions legislations," in Thermo-and Fluid Dynamic Processes in
Diesel Engines 2, ed: Springer, 2004, pp. 235-254.
[9] [9] M. L. Sattler, "Technologies for reducing NOx emissions from nonroad
diesel vehicles: An Overview," White paper, published in EM a publication
of the Air & Waste Management Association for Environmental Managers,
pp. 20-29, 2002.
[10] [10] Y.-D. Kim, W.-S. Kim, and Y. Lee, "Influences of exhaust gas
temperature and flow rate on optimal catalyst activity profiles," International
Journal of Heat and Mass Transfer, vol. 85, pp. 841-851, 2015.
[11] [11] S.-J. Jeong and W.-S. Kim, "Three-dimensional numerical study on the
use of warm-up catalyst to improve light-off performance," SAE Technical
Paper 0148-7191, 2000.
[12] [12] J. Chen, H. Yang, N. Wang, Z. Ring, and T. Dabros, "Mathematical
modeling of monolith catalysts and reactors for gas phase reactions," Applied
Catalysis A: General, vol. 345, pp. 1-11, 2008.
[13] [13] C. Ozhan, D. Fuster, and P. Da Costa, "Multi-scale flow simulation of
automotive catalytic converters," Chemical Engineering Science, vol. 116,
pp. 161-171, 2014.
[14] [14] A. Kumar and S. Mazumder, "Toward simulation of full-scale
monolithic catalytic converters with complex heterogeneous chemistry,"
Computers & chemical engineering, vol. 34, pp. 135-145, 2010.
[15] [15] L. C. YOUNG and B. A. FINLAYSON, "Mathematical modeling of
the monolith converter," ed: ACS Publications, 1974.
[16] [16] N. B. Ferguson and B. A. Finlayson, "Transient modeling of a catalytic
converter to reduce nitric oxide in automobile exhaust," AIChE Journal, vol.
20, pp. 539-550, 1974.
[17] [17] R. H. Heck, J. Wei, and J. R. Katzer, "Mathematical modeling of
monolithic catalysts," AIChE Journal, vol. 22, pp. 477-484, 1976.
[18] [18] W. Taylor, "CFD prediction and experimental validation of high-
temperature thermal behavior in catalytic converters," SAE Technical Paper
0148-7191, 1999.
[19] [19] H. Santos and M. Costa, "Analysis of the mass transfer controlled
regime in automotive catalytic converters," International journal of heat and
mass transfer, vol. 51, pp. 41-51, 2008.
[20] [20] G. Groppi and E. Tronconi, "Theoretical analysis of mass and heat
transfer in monolith catalysts with triangular channels," Chemical
engineering science, vol. 52, pp. 3521-3526, 1997.
[21] [21] A. Holmgren, T. Grönstedt, and B. Andersson, "Improved flow
distribution in automotive monolithic converters," Reaction Kinetics and
Catalysis Letters, vol. 60, pp. 363-371, 1997.
[22] [22] M.-C. Lai, J.-Y. Kim, C.-Y. Cheng, P. Li, G. Chui, and J. Pakko,
"Three-dimensional simulations of automotive catalytic converter internal
flow," SAE transactions, pp. 241-250, 1991.
[23] [23] K. Ramanathan, V. Balakotaiah, and D. H. West, "Light-off criterion
and transient analysis of catalytic monoliths," Chemical Engineering Science,
vol. 58, pp. 1381-1405, 2003.
[24] [24] J. Braun, T. Hauber, H. Többen, J. Windmann, P. Zacke, D. Chatterjee,
et al., "Three-dimensional simulation of the transient behavior of a three-way
catalytic converter," SAE Technical Paper 0148-7191, 2002.
[25] [25] V. Chakravarthy, J. Conklin, C. Daw, and E. D’Azevedo, "Multi-
dimensional simulations of cold-start transients in a catalytic converter under
steady inflow conditions," Applied Catalysis A: General, vol. 241, pp. 289-
306, 2003.
[26] [26] R. Hayes, A. Fadic, J. Mmbaga, and A. Najafi, "CFD modelling of the
automotive catalytic converter," Catalysis today, vol. 188, pp. 94-105, 2012.
[27] [27] S. F. Benjamin, Z. Liu, and C. A. Roberts, "Automotive catalyst design
for uniform conversion efficiency," Applied Mathematical Modelling, vol.
28, pp. 559-572, 2004.
[28] [28] M. Shelef and R. W. McCabe, "Twenty-five years after introduction of
automotive catalysts: what next?," Catalysis today, vol. 62, pp. 35-50, 2000.
[29] [29] G. C. Koltsakis and A. M. Stamatelos, "Catalytic automotive exhaust
aftertreatment," Progress in Energy and Combustion Science, vol. 23, pp. 1-
39, 1997.
[30] [30] E. Karvounis and D. N. Assanis, "The effect of inlet flow distribution
on catalytic conversion efficiency," International journal of heat and mass
transfer, vol. 36, pp. 1495-1504, 1993.
[31] [31] A. Martin, N. Will, A. Bordet, P. Cornet, C. Gondoin, and X. Mouton,
"Effect of flow distribution on emissions performance of catalytic
converters," SAE transactions, pp. 384-390, 1998.
[32] [32] G. Bella, V. Rocco, and M. Maggiore, "A study of inlet flow distortion
effects on automotive catalytic converters," 1991.
[33] [33] S. H. Amirnordin, S. M. Seri, W. Salim, H. A. Rahman, and K. Hasnan,
"Pressure drop analysis of square and hexagonal cells and its effects on the
performance of catalytic converters," International Journal of Environmental
Science and Development, vol. 2, pp. 239-247, 2011.
[34] [34] F. Ekström and B. Andersson, "Pressure drop of monolithic catalytic
converters experiments and modeling," SAE Transactions, pp. 425-433,
2002.
International Journal of Scientific and Research Publications, Volume 10, Issue 3, March 2020 105
ISSN 2250-3153
http://dx.doi.org/10.29322/IJSRP.10.03.2020.p9908 www.ijsrp.org
[35] [35] S.-J. Shuai and J.-X. Wang, "Unsteady temperature fields of monoliths
in catalytic converters," Chemical Engineering Journal, vol. 100, pp. 95-107,
2004.
[36] [36] M. Chen and K. Schirmer, "A modelling approach to the design
optimization of catalytic converters of IC engines," in ASME 2003 Internal
Combustion Engine and Rail Transportation Divisions Fall Technical
Conference, 2003, pp. 201-207.
[37] [37] Y.-S. Cho, D.-S. Kim, M. Han, Y. Joo, J.-H. Lee, and K.-D. Min, "Flow
distribution in a close-coupled catalytic converter," SAE transactions, pp.
1343-1349, 1998.
[38] [38] M.-C. Lai, T. Lee, J.-Y. Kim, C.-Y. Cheng, P. Li, and G. Chui,
"Numerical and experimental characterizations of automotive catalytic
converter internal flows," Journal of Fluids and Structures, vol. 6, pp. 451-
470, 1992.
[39] [39] H. Weltens, H. Bressler, F. Terres, H. Neumaier, and D. Rammoser,
"Optimisation of catalytic converter gas flow distribution by CFD
prediction," SAE Technical Paper 0148-7191, 1993.
[40] [40] B. Liu, R. Hayes, Y. Yi, J. Mmbaga, M. Checkel, and M. Zheng, "Three
dimensional modelling of methane ignition in a reverse flow catalytic
converter," Computers & chemical engineering, vol. 31, pp. 292-306, 2007.
[41] [41] G. Agrawal, N. S. Kaisare, S. Pushpavanam, and K. Ramanathan,
"Modeling the effect of flow mal-distribution on the performance of a
catalytic converter," Chemical engineering science, vol. 71, pp. 310-320,
2012.
[42] [42] H. Bressler, D. Rammoser, H. Neumaier, and F. Terres, "Experimental
and predictive Investigation of a close coupled catalyst converter with
pulsating flow," SAE transactions, pp. 255-267, 1996.
[43] [43] T. Shamim, H. Shen, S. Sengupta, S. Son, and A. Adamczyk, "A
comprehensive model to predict three-way catalytic converter performance,"
J. Eng. Gas Turbines Power, vol. 124, pp. 421-428, 2002.
[44] [44] C.-M. Chung, C.-C. Chen, W.-P. Shih, T.-E. Lin, R.-J. Yeh, and I.
Wang, "Automated machine learning for Internet of Things," in 2017 IEEE
International Conference on Consumer Electronics-Taiwan (ICCE-TW),
2017, pp. 295-296.
[45] [45] J. von Rickenbach, F. Lucci, C. Narayanan, P. D. Eggenschwiler, and
D. Poulikakos, "Multi-scale modelling of mass transfer limited
heterogeneous reactions in open cell foams," International Journal of Heat
and Mass Transfer, vol. 75, pp. 337-346, 2014.
[46] [46] K. A. McNitt, K. Parimal, A. I. Share, A. C. Fahrenbach, E. H. Witlicki,
M. Pink, et al., "Reduction of a redox-active ligand drives switching in a Cu
(I) pseudorotaxane by a bimolecular mechanism," Journal of the American
Chemical Society, vol. 131, pp. 1305-1313, 2009.
[47] [47] V. Okoye, J. Sands, and C. A. Debrah, "The Accra pilot Bus-Rapid
Transit project: Transport-land use research study," Millennium Cities
Initiative and Accra Metropolitan Assembly, The Earth Institute at Columbia
University, New York. URI: http://mci. ei. columbia.
edu/files/2013/03/Transport-Land-Use-Research-Study. pdf, 2010.
[48] [48] P. Y. G. Owusu, "Youth Entrepreneurship in Auto Spare Parts Sales
and Repair Service in Accra, Ghana."
[49] [49] S. Amedorme and K. Agbezudor, "Investigation of vehicle alterations
and modifications at Suame Magazine in Kumasi, Ghana," Int. J. Mech. Eng.
Res. Appl, vol. 1, pp. 48-53, 2013.
[50] [50] T. Jaarsma, H. Maat, P. Richards, and A. Wals, "The role of materiality
in apprenticeships: the case of the Suame Magazine, Kumasi, Ghana,"
Journal of Vocational Education & Training, vol. 63, pp. 439-449, 2011.
AUTHORS
First Author Isaac Tekper, Dept. of Mechanical Engineering,
Kumasi Technical University, Kumasi, 00233, Ghana
Second Author Joseph Kwame Lewballah, Dept. of
Mechanical Engineering, Kumasi Technical University, Kumasi,
00233, Ghana
Third Author James Kwasi Quaisie, School of Mechanical
Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013,
China
Fourth Author Fred Joseph Komla Adzabe, Dept. of
Mechanical Engineering, Kumasi Technical University, Kumasi,
00233, Ghana
Fifth Author Emmanuel Yeboah Osei, Dept. of Mechanical
Engineering, Kumasi Technical University, Kumasi, 00233,
Ghana
Sixth Author Emmanuel Asamoah, School of Mechanical
Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013,
China
Seventh Author Philip Baidoo, Faculty of Technology,
University of Education Winneba, Kumasi, 00233, Ghana
Eight Author Andrews Danquah, Dept. of Mechanical
Engineering, Kumasi Technical University, Kumasi, 00233,
Ghana
Chapter
Platinum group metals (PGM) are used as a catalyst in the automotive catalytic converters to curb engine emissions. The modern catalytic converter (three-way) executes oxidation of CO and unburnt HC, and reduction of NO using its large active surfaces containing PGM, which are precious metals with high cost all over the world. Due to the high cost of the PGM, researchers are working on efficient methods for extracting and reusing these valuable metals from catalytic converters. Pyrometallurgy and hydrometallurgy are the most common ways for the extraction of the PGMs among other methods. Alternative to platinum, materials like titanium dioxide and other metal-based oxides can be used for carrying out redox reactions of toxic vehicular emissions. The use of such alternative catalysts can help in reducing the increasing demands and cost of PGMs. This chapter focuses on the possibilities of recycling the PGMs from catalytic converters and also of reducing the ever-increasing requirement of PGMs in the manufacturing of autocatalysts in the catalytic converters. The chapter reports the recent global trends of PGM recycling and its demand for use as autocatalysts, alternative materials of to PGMs in catalytic converters and alternative methods for emission reduction. Further, the engine-related challenges and research on future directions of replacing PGM’s as autocatalysts has been performed; it includes some experimental results of direct decomposition of NOx using non-noble metal catalysts such as Cu-COK12, Cu-Nb2O5, Cu-YZeolite, and Cu-ZSM5. The article should also provide a quicker understanding of research on development of low-cost non-noble metal-based alternative autocatalysts.KeywordsAlternative catalystsAutocatalystsDemandPGMRecyclingSupply
Article
Full-text available
Background: The International Agency for Research on Cancer (IARC) classifies diesel engine exhaust as carcinogenic to humans based on sufficient evidence for lung cancer. IARC noted, however, an increased risk of bladder cancer (based on limited evidence). Objective: To evaluate the association between quantitative, lifetime occupational diesel exhaust exposure and risk of urothelial cell carcinoma of the bladder (UBC) overall and according to pathological subtypes. Methods: Data from personal interviews with 1944 UBC cases, as well as formalin-fixed paraffin-embedded tumor tissue blocks, and 2135 controls were pooled from two case-control studies conducted in the U.S. and Spain. Lifetime occupational histories combined with exposure-oriented questions were used to estimate cumulative exposure to respirable elemental carbon (REC), a primary surrogate for diesel exhaust. Unconditional logistic regression and two-stage polytomous logistic regression were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for smoking and other risk factors. Results: Exposure to cumulative REC was associated with an increased risk of UBC; workers with cumulative REC >396 μg/m3-years had an OR of 1.61 (95% CI, 1.08-2.40). At this level of cumulative exposure, similar results were observed in the U.S. and Spain, OR = 1.75 (95% CI, 0.97-3.15) and OR = 1.54 (95% CI, 0.89-2.68), respectively. In lagged analysis, we also observed a consistent increased risk among workers with cumulative REC >396 μg/m3-years (range of ORs = 1.52-1.93) for all lag intervals evaluated (5-40 years). When we accounted for tumor subtypes defined by stage and grade, a significant association between diesel exhaust exposure and UBC was apparent (global test for association p = 0.0019). Conclusions: Combining data from two large epidemiologic studies, our results provide further evidence that diesel exhaust exposure increases the risk of UBC.
Article
Full-text available
Stringent emission regulations around the world necessitate the use of high-efficiency catalytic converters in vehicle exhaust systems. Therefore, determining the optimum geometry of the honeycomb monolith structure is necessary. This structure requires a high surface area for treating gases while maintaining a low pressure drop in the engine. In the present paper, an adapted sub-grid scale modeling is used to predict the pressure loss of square-and hexagonal-cell-shaped honeycomb monoliths. This sub-grid scale modeling represents the actual variations in the pressure drop between the inlet and outlet for various combinations of wall thickness and cell density. A comparison is made between the experimental and numerical results established in literature. The present approach is found to provide better and more comprehensive results than the single channel technique.
Article
Full-text available
Mathematical models for the monolith converter are developed and applied to the oxidation of carbon monoxide in automobile exhausts. The converter consists of an array of ducts with catalyst coating the walls. The exhaust gas flows axially through the ducts in laminar flow. Two models for this type of converter are proposed and solved numerically. The simpler model uses heat and mass transfer coefficients for fully developed flow in ducts to account for the resistance to transfer between the fluid and the catalytic wall. The more complicated model accounts for the distribution of mass and energy in the duct cross-section, which is assumed to be circular. Both transient and steady-state calculations are performed for conditions which would be expected during vehicle operation.
Article
Background: Miners are highly exposed to diesel exhaust emissions from powered equipment. Although biologically plausible, there is little evidence based on quantitative exposure assessment, that long-term diesel exposure increases risk of chronic obstructive pulmonary disease (COPD). To fill this gap, we examined COPD mortality and diesel exhaust exposure in the Diesel Exhaust in Miners Study (DEMS). Methods: We fit Cox models to estimate hazard ratios (HRs) for COPD mortality and cumulative exposure (μg/m3-years) to respirable elemental carbon (REC), a key metric for diesel exhaust exposure. Separate models were fit for ever-underground and surface-only miners to allow for effect modification. Exposure was lagged by 0, 10 and 15 years. In a secondary analysis, we addressed the healthy worker survivor effect by applying the parametric g-formula to handle time-varying confounding affected by prior exposure among ever-underground workers. Results: Based on 140 cases, the HRs for COPD mortality increased as categories of lagged REC exposure increased for all workers. Among surface-only workers, those in the middle exposure category (0 lag) had a significantly elevated hazard ratio of 2.34 (95% CI: 1.11-4.61) relative to those in the lowest category. Among the ever-underground, that ratio was 1.35, with wide confidence intervals. Using the g-formula, we estimated that the lifetime cumulative risk of COPD mortality would have been reduced from the observed 5.0%-3.1% under a hypothetical intervention where all ever-underground workers were always unexposed. Conclusions: Our results suggest long term exposure to diesel exhaust may increase risk of COPD in miners, though power was limited.
Conference Paper
Performance improvements, of catalytic converters, and longer service life can be achieved by improving the flow distribution of exhaust gases. Computational Fluid Dynamics (CFD) is an excellent and relatively inexpensive technique for rapid and efficient optimization of the flow. Studies indicate that a 3D representation is necessary because 2D is insufficient. The computations are confirmed by measurements of steady flow. A number of design parameters are systematically investigated and their effects on an index of flow uniformity established. The parameters include the geometry of the inlet tube and inlet cone, the geometry and placement of the monoliths, and the shape of the exit cone. The difficult flow conditions in close coupled converters are examined. The flow path is improved and the best location of the HEGO-sensor found. (A) For the covering abstract see IRRD 858138.
Article
HC and CO emissions during the cold start contribute the majority of the total emissions in the legislated driving cycles. Therefore, in order to minimize the cold-start emissions, the fast light-off techniques have been developed and presented in the literature. One of the most encouraging strategies for reducing start-up emissions is to place the warm-up catalyst, in addition to the main under-body catalyst, near the engine exhaust manifold. This study numerically considers three-dimensional, unsteady compressible reacting flow in the warm-up and main catalysts to examine the impact of a warm-up catalyst on thermal response of the main catalyst and tail pipe emission. The effects of flow distribution and loading condition on the temperature distribution and emission performance have also been investigated. The present results show that flow distribution has a great influence on the temperature distribution in the monolith at the early stage of warm-up process and optimal catalyst distribution of high loading at the entrance has no effect on conversion improvement when the space velocity is too fast for reaction to complete within high loading region (above SV=100,000 hr-1).