D.L. Hoang

Heat transfer and chemical reactions in exhaust system of a cold-start engine

Abstract Modelling of cold-start engine exhaust behaviour is a difficult task as it involves complicated heat transfer processes and chemical reactions at both the exhaust manifold/pipe and catalytic converter. This paper presents a model that is capable of predicting the exhaust gas temperatures along the exhaust pipe and across the catalyst monolith, both spatially and temporally. The dew point temperature platform, due to water condensation and subsequent evaporation, at catalysts downstream immediately after engine cold-start is successfully predicted. The conversions of toxic carbon monoxide and unburned hydrocarbons to harmless carbon dioxide and water at the catalytic converter are also validated satisfactorily by the experimental data.

A Thermodynamic View of Partial Oxidation, Steam Reforming, and Autothermal Reforming on Methane

Abstract Thermodynamic analysis on three thermo-chemical reforming processes, i.e., partial oxidation (POX), steam reforming (STR), and autothermal reforming (ATR) with methane as the feedstock fuel are conducted in this study. The focus of this article is to show the effect of air-fuel (AF) ratio, water-fuel (WF) ratio, temperature and pressure on hydrogen (H2) yield, hydrogen/carbon monoxide (H2/CO) ratio, carbon (C), and carbon monoxide (CO) formation. Optimal operating conditions under no solid carbon formation in the reaction are recommended for each thermochemical reforming technique.

Heat transfer and chemical kinetics in the exhaust system of a cold-start engine fitted with a three-way catalytic converter

Abstract Modelling of cold-start engine exhaust behaviour is a difficult task as it involves complicated heat transfer processes associated with water condensation and evaporation at the walls of the exhaust manifold/pipe and monolith cells, and the chemical reactions of CO/HC/NO in the three-way catalytic converter. This paper presents a model that is capable of predicting the exhaust gas temperatures along the exhaust system and across the catalyst monolith, both spatially and temporally, from the moment when the engine is cranked. The conversions of CO/HC/NO to harmless carbon dioxide, water and nitrogen at the catalytic converter downstream have been validated satisfactorily by the experimental data. The distortion of measured NO emission data/signals due to the dynamic behaviour of the chemiluminescence analyser has been reconstructed by means of a signal inference technique before these signals were used to validate the predictive capability of the model developed.

Chemical Reactions in the Exhaust System of a Cold-start Engine

Transient heat transfer and water condensation in the engine exhaust system have a strong influence on the conversion of carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NO x ) in the three-way catalytic converter (TWC) of an engine cold-start. This paper presents the theoretical modeling of heat transfer and chemical reactions of CO, HC, and NO associated with the effects of catalyst surface water vapor condensation, and water evaporation in the entire engine exhaust system fitted with a TWC. The predictive capability of the model is validated successfully with the experimental data.