In this research study, a synthetic exhaust gas system is employed to simulate various exhaust conditions similar to those from conventional diesel and Dual Fuel-Premixed Charge Compression Ignition (DF-PCCI) combustion. OEM DOC is tested to compare the effectiveness of reducing CO from both exhaust characteristics. Variations of the temperature and the concentration of CO, THC, and O2 are done to investigate DOC performance on CO reductions according to Design of Experiment (DOE) concept. The results showed that in DF-PCCI exhaust conditions, DOC requires higher exhaust gas temperature as well as O2 concentration to reduce CO emissions.

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Abstract.A Diesel Dual Fuel (DDF) engine is an adapted diesel engine that uses natural gas and diesel fuel as the energy source at the same time. Natural gas is mixed with air at the intake manifold while diesel fuel is injected into the combustion chamber directly to initiate the combustion process. Based on the past DDF literatures, they are indicated that Carbon Monoxide (CO) emissions were more substantial at low load conditions than those when running in diesel engine modes. The Diesel Oxidation Catalyst (DOC) that is installed to this diesel engine is, therefore, not capable to reduce CO emissions abide by to the emission regulation. Literatures also indicate that the exhaust temperature, mass flow rate, Oxygen (O2) concentration, CO concentration, as well as Propane (C3H8) concentration may affect CO conversion efficiency of the catalytic converter. In the present work, Design of Experiments (DOE) is employed to explore the behavior of various factors that affect CO reductions in the catalytic converter. Once the knowledge is founded, the optimization of CO reductions in the catalytic converter at 90% is studied extensively.Using Fractional Factorial Design for screening factors on CO conversions, it is found that the exhaust temperature, mass flow rate, O2 concentration, and CO concentration affect CO conversions of the catalytic converter significantly. Optimization of these factors, by using Box-Behnken Design, for reducing CO concentration of 6200 ppm which is the maximum CO amount emitted from the tested engine shows that 90% of CO conversion can be reached at the exhaust temperature of 200 0 C, the mass flow rate of 25 kg/h, and the oxygen concentration of 16%.

This current research work has been focused on Methane (CH4) reduction in a Diesel Oxidation Catalyst (DOC) emitted from a Dual Fuel-Premixed Charged Compression Ignition (DF-PCCI) engine. This new alternative combustion technology is implemented on a Diesel Engine powered by both diesel fuel and natural gas in order to reduce diesel fuel usage and maintain the same thermal efficiency. However, the drawback lies in higher amount of CH4 in the exhaust that might effects Original Equipment Manufacturer (OEM)'s DOC performance. In this work, thermophysical and chemical properties of DF-PCCI exhaust such as temperature, flow rate, and specie concentrations are varied to investigate their effects on CH4 conversion efficiency in DOC. Design of Experiment (DOE) is built and tested in a Synthetic Exhaust Gas Generating System that can simulate the DF-PCCI exhaust-like conditions and all tested parameters are fully controlled. The experimental matrix is selected to cover DF-PCCI exhaust condition ranges to optimizing CH4 treatment. A kinetic model with water concentration is also investigated and compared to DOE model and experimental data. It is shown that the major factors that influence methane oxidation are exhaust flow rate, H2O concentration, and exhaust temperature (at P-value < 0.05 or at confidence level of 95%). The DOE model for predicting CH4 reductions is also generated.