Mathematical modelon a three way catalytic converter: a comparative study of gas phase concentration and temperature

Project Abstract

<p> </p><p>We comparatively studied gas phase concentration and gas temperature of three way catalytic<br>converter models. We considered channel level models and provided concise solutions for them.<br>Solutions to the models were graphically represented and we found that gas phase temperature<br>increases with time and gas phase concentration of gaseous species attain light-off at temperature<br>above 600K.</p><p>&nbsp;</p><p><strong>&nbsp;</strong></p> <br><p></p>

Project Overview

<p> INTRODUCTION<br>The Combustion of fuel in the engine always releases some harmful by-products which<br>are majorly hydrocarbon, carbon monoxides and oxides of nitrogen. These dangerous gases<br>emitted by the exhaust engine have been a major source of air pollution. The alarming increase<br>in the number of automobiles due to economic growth in some developing countries has also<br>aided the increase of these pollutants which have been causing so much damage to nature and<br>human life. Efforts to combat this menace has been on for more than three decades.<br>In the early 1950’s when the reality of pollution began to dun on the world. The federal<br>government carried out a research to determine its course and found that automobiles are one of<br>the biggest sources of emissions. This led to the enactment of different laws to enforce pollution<br>control from automobiles according to Agency, (1994). For instance, the clean Air Act of 1970<br>gave the environmental protection agency(EPA) authority to regulate vehicles pollution.<br>Consequently, EPA dictated allowed quantity of each species emitted which is presented in<br>Agency,(1994) and Chorkendorff and Niemantsverdriet,(2007).The first federal legislation<br>regarding emission limits in the United States also came in 1975. These laws have necessitated<br>the use of a three- way catalytic converter by the automobile companies. This device located in<br>line with the exhaust system has been used to cause a desirable chemical reaction in the exhaust<br>flow by completing the oxidation process for hydrocarbon (HC) and carbon monoxides (CO) to<br>carbon dioxide and water; and Oxides of Nitrogen (NOx) back to Simple Nitrogen.<br>Due to the ever increasing stringent safety measures, there has been need for the<br>improvement of the existing three-way catalytic converters. Efforts are being made to optimize<br>2<br>the converter geometry, substrates selection andwashcoat materials and the converter location in<br>the exhaust system and a great understanding of the gaseous flow through the thin channels of<br>the monolith while the gases are reacting which largely depends on the concentration of the<br>gaseous species and the exhaust gas temperature as they flow will help in designing monolith<br>that can function efficiently at any temperature. In other to minimize the cost and time that will<br>be wasted in design, mathematical modelling is best suited for this optimization.<br>1.2 MOTIVATION FOR THE STUDY<br>There has been a growing interest in using mathematical models for the improvements of<br>the existing three-way catalytic converters. Several approaches exist for the modelling of mass<br>transport which completely neglects the washcoat diffusion for simplicity although evidence of<br>diffusion is important according to Massing et al(2000) and Hayes and Kolaczkowski(1994). We<br>want to look into channel level modeling which accounts for the gas-phase concentration and the<br>exhaust gas temperature to provide simple solution to the model and compare the effect of<br>concentration and temperature to the light-off ofa catalytic converter.<br>1.3 OBJECTIVES OF THE STUDY<br>The aims/objectives of the study are:<br>a) To provide a concise solution to the channel level models.<br>b) To use the solution we obtained to investigate the effect of gas-phase concentration and<br>exhaust gas temperature on the conversion efficiency of catalytic converter.<br>3<br>1.4 SCOPE OF THE STUDY<br>This study will focus on formulating a model for the expression of gas-phase concentration<br>and exhaust gas temperature using channel level modeling. We shall not consider other levels of<br>modeling of catalytic converter and there complexities. <br></p>