Numerical Simulation Of Nitrous Oxide And Carbon Monoxide Abatement In The Catalytic Converter Of A Compressed Natural Gas Engine
Air pollution in Malaysia is mainly caused by emission from motor vehicles according to the Department of Environment (DOE). The Malaysia Government through DOE has been regulating vehicles emissions with more stringent regulations on nitrogen oxides and carbon monoxide emissions gazetted since 1...
محفوظ في:
| المؤلف الرئيسي: | |
|---|---|
| التنسيق: | أطروحة |
| اللغة: | English English |
| منشور في: |
2008
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| الموضوعات: | |
| الوصول للمادة أونلاين: | http://psasir.upm.edu.my/id/eprint/5339/1/FK_2008_2.pdf |
| الوسوم: |
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| الملخص: | Air pollution in Malaysia is mainly caused by emission from motor vehicles
according to the Department of Environment (DOE). The Malaysia Government
through DOE has been regulating vehicles emissions with more stringent regulations
on nitrogen oxides and carbon monoxide emissions gazetted since 1996. Catalytic
converters are one of the effective devices to reduce air pollution by motor vehicles
by transforming nitrogen oxides and carbon monoxide in the exhaust to relatively
harmless nitrogen and carbon dioxide respectively. A catalytic converter is easy to
fit into any exhaust system, not bulky and does not require much maintenance.
However, due to the presence of precious group metals such as platinum, rhodium
and palladium as catalysts, the cost of the catalytic converter is relatively high.
Furthermore, the catalysts’ activation and deactivation levels is highly dependent on
temperature, hence the design of catalytic converter in the vehicle exhaust system is
not easy.
The objective of this study is to carry out simulation via CFD code FLUENT 6.0, on
catalytic converter design and efficiency in a cold start natural gas engine for
nitrogen monoxide and carbon monoxide emission control. CFD code FLUENT 6.0 was used for prediction of catalytic converter light-off
temperature and efficiency. Cold start and light-off temperatures are the acceptable
worst scenario for compressed natural gas (CNG) engine pollutants abatement in
order to achieve low emission vehicle. The simulation result was then verified via
experimental data published in the literature. Another CFD modelling module was
conducted to predict the exhaust gas temperature at 10cm, 30cm, 50cm, 80cm and
110cm from the engine outlet to determine the best position of catalytic converter in
the exhaust system. A third CFD modelling module was done to simulate the
surface reactions on a single channel of a catalytic converter. This is the contribution
to the knowledge in the pollutants abatement in catalytic converter. The simulation
result was then verified via experimental data published in the literature.
The simulation of catalytic converter light-off temperature for NO and CO were
proved to be satisfactory when compared to presented experimental result.
Simulated NO conversion efficiency was in agreement with presented experimental
result. However, CO conversion simulation result was not well predicted compared
with presented experimental result. This is because FLUENT 6.0 surface reaction
does not take surface coverage into account. Simulation of exhaust gas temperature
showed that it is not advisable to place the catalytic converter below 25cm or above
80cm from the engine outlet. It is found that CFD FLUENT 6.0 can be used to
simulate surface reaction on a single channel by adjusting the Arrhenius constants by
a factor of 10-15 for CO reaction and factor of 10-16 for NO reaction. |
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