Journal of Information and Computational Science ISSN: 1548-7741

Effect of Cone Angle on Performance of Ch.Indira Priyadarsini, Dr.T.Ratna Reddy, Mr.N.Chandra Sekhar, R. Hathiram

Assistant Professor, Mechanical Engg. Dept., Chaitanya Bharathi Institute of Technology Hyderabad, [email protected] Associate Professor, Mechanical Engg. Dept., Chaitanya Bharathi Institute of Technology Hyderabad, [email protected]

ABSTRACT Catalytic converter plays a vital role in reducing harmful gases, but the presence of catalytic converter increases the exhaust back pressure. Catalytic converter is the main control device for modern vehicles in order to reach the ever-increasing legislative demands for low emission standards. in this work a flow analysis is carried out by varying four different Cone angles 45o, 60o. The velocity, pressure and temperature flow in converter has been presented for different configurations. It is observed velocity profile is uniform for 450 cone angle compared to 60 and even back pressure also less with 450 angle for pipe diameter of 0.018m.

Keywords— Cone angle, Catalytic converter, CFD, Fluent, Performance

I. INTRODUCTION A catalytic converter is a device used to reduce the emissions from an internal combustion engine (used in most modern day automobiles and vehicles). Not enough oxygen is available to oxidize the carbon fuel in these engines completely into carbon dioxide and water; thus toxic by-products are produced. Catalytic converters are used in exhaust systems to provide a site for the oxidation and reduction of toxic by-products (like nitrogen oxides, carbon monoxide, and hydrocarbons) of fuel into less hazardous substances such as carbon dioxide, water vapour, and nitrogen gas.

Fig.1 Working of Catalytic converter Functions A three-way catalytic converter has three simultaneous functions: 1. Reduction of nitrogen oxides into elemental nitrogen and oxygen: Volume 13 Issue 12 – 2020 www.joics.net 73

Journal of Information and Computational Science ISSN: 1548-7741

NOx→Nx+Ox 2. Oxidation of carbon monoxide to carbon dioxide: CO+O2→CO2 3. Oxidation of hydrocarbons into carbon dioxide and water: CxH4x+2xO2→xCO2+2xH2O There are two types of "systems" running in a catalytic converter, "lean" and "rich." When the system is running "lean," there is more oxygen than required, and the reactions therefore favour the oxidation of carbon monoxide and hydrocarbons. On the contrary, when the system is running "rich," there is more fuel than needed, and the reactions favour the reduction of nitrogen oxides into elemental nitrogen and oxygen. With a constant imbalance of the reactions, the system never achieves 100% efficiency.

Fig.2 Catalytic converter sectional view II. LITERATURE REVIEW In recent years, several proposals were made for the numerical simulation of catalytic converter. In most of these studies, a global model for the was used, which neglected the complex network of chemical reactions on the catalytic surface. An alternate approach is the description of the chemical reactions by a set of elementary-like reaction steps describing the chemical processes on a molecular level by Chatterjee et.al. [1]. Al for 3WCC. On rhodium, surface reactions only between NO, CO, and O2 are considered. The modeling and numerical simulation of steady-state and transient processes in automotive catalytic converters are discussed. A DeNOxcatalyst is investigated. The fundamental understanding of complex processes taking place involving fluid flow, pressure, velocity profiles in the catalytic converter. The study of pressure contours and velocity vectors of fluid flow inside the catalytic converter are explained using numerical model by Indira priyadarsini et.al. [2] In most of the converters, the ceramic is a single honey comb structure with many flow passages. The passages comprises of many shapes, including square, triangular, hexagonal and sinusoidal. Early converters used loose granular ceramic with the gas passing between the packed spheres. Since it is difficult to keep the sphere in place, many converter developers opted for ceramic monolith which offers various advantages. Among these advantages are smaller Volume 13 Issue 12 – 2020 www.joics.net 74

Journal of Information and Computational Science ISSN: 1548-7741

volumes, lower mass and greater ease of packaging Heck et al. [3]. The active catalyst layer is applied on the monolith walls. The coating, called wash coat, is composed of porous, high surface area inorganic oxides such as γ- Al2O3 (gamma alumina), CeO2 (Ceria) and ZrO2 (Zirconia). Noble metal catalyst, such as (Pt), Palladium (Pd) and Rhodium (Rh), are deposited on the surface and within the pores of the wash coat Pontikakis [4]. Exhaust gas flowing in a catalytic converter diffuses through the wash coat pore structure to the catalytic sites where heterogeneous catalytic reactions occur. The specific reactions vary with the type of catalyst installed. Most present17 day vehicles that run on gasoline are fitted with a ―three way‖ converter, so named because it converts the three main pollutants in automobile exhaust: carbon monoxide, unburned hydrocarbon and oxides of nitrogen. The first two undergo catalytic combustion and the last is reduced back to nitrogen. The nature of the exhaust gas flow is very important factor in determining the performance of catalytic converter. The pressure gradient and velocity distribution through the substrate are important in particular. Therefore CFD analysis is used to design efficient catalytic converters by modeling the exhaust gas flow, the pressure drop and the uniformity of flow through the substrate can be determined. In this paper ANSYS FLUENT (ANSYS Work Bench 14.5, Fluid Flow-Fluent) is used to model the flow of exhaust gas through catalytic converter, so that the flow field may be analyzed. Catalyst substrates coated with the active catalyst wash coat are packaged in steel housings to form catalytic converters. Emission performance durability and mechanical durability are the two key aspects of the overall durability of an emission control system. The emission durability depends on the quality of the catalyst coating and on the operating conditions such as temperature or levels of catalyst poisons in the exhaust gas. In CFD, the system consumes less memory space and less response time, if the rectangular cross section is assumed. However, in actual practice, the rectangular corners are suitably rounded off which ensures the smooth flow of exhaust gas with less turbulence near the wall sides. On the other hand, the flow characteristics of the exhaust gas such as flow velocity, temperature, composition of raw emissions and flow distribution play an important role for the conversion Rate and light-off behavior of catalytic converter Michael G. Campbell , Chandler.G.R [5,6]. Francisco et al. studied one-dimensional fluid –dynamic Model for catalytic converter in automotive engines. Th e main aim of this paper was to present a simple approach to the onedimensional modelling of the fluid dynamic behaviour of the catalytic converter. They developed a geometric model that was capable of completely representing the dynamic behaviour of the converter, that is, its reflection and transmission characteristics. Cathy Chung et al.[7] studied the CFD investigation of thermal fluid flow and conversion characteristics of the catalytic converter. Their main objective was to predict the maximum operating temperature for appropriate materials and to develop a numerical model, which can be adjusted to reflect changes in the catalyst/wash coat formulation to accurately predict effects of flow, temperature and light off behaviour. They concluded that by changing the 18 concentrations, the converter characteristics and steady state temperature could be changed. Olaf Deutschmann et.al.[8] studied detailed surface reaction mechanism in a three- way catalytic converter. In this paper, two-dimensional flow field description, including detailed reaction mechanism for the conversion of CO, C3H6, and NO has been used to simulate the exhaust gas treatment in a platinum/rhodium coated single channel of a typical three-way catalytic converter. The simulation is based on the CFD code FLUENT and the chemistry module DETCHEM, which were coupled for the simulations temperature

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Journal of Information and Computational Science ISSN: 1548-7741

field of the monolithic solid structure of the converter. For the numerical simulation of transient behavior of three- way catalytic converter a newly developed CFD code DETCHEM was used. For this study, experiments were carried out on an engine test bench. A 4-cylinder 1.6 Litres SI engine was used. III MATERIALS AND METHODOLOGY Modeling was created using CATIAV5 and fugure is shown below with dimensions from experimental setup. The geometry was imported to ansys fluent where discratization is performed using control volume method. The boundary conditions were applied based on experimental results with real time operating conditions.

Fig.3 Dimensions of Catalytic Convertor

Fig.4 Catalytic Convertor with 45 degree cone angle

Fig.5 Catalytic Convertor with 60 degree cone angle

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Journal of Information and Computational Science ISSN: 1548-7741

Fig.6 Boundary Conditions

IV RESULTS AND DISCUSSION 4.1 Angle of 450

(a) (b) (c) Fig.7 (a)Velocity Magnitude, (b) Static Pressure (c) Static Temperature Fig.7 shows the contours of velocity, is increased from inlet of 1.02m/s to 2.04m/s outlet. Velocity is increased due to diffusion action of increasing area and decrease area of nozzle. Velocity is uniform through the pipes because flow of gas in porous media consider as laminar. The contours of Pressure, is decreased from inlet of 7.74bar to - 1.19bar outlet. Pressure is decrease due to diffusion action of increasing area and decrease area of nozzle. Pressure is uniform at the top and bottom pipes and flow is less in middle pipes. the contours of temperature, is decreased from inlet of 7.73e2K to 3.86k outlet. Temperature is decrease due to diffusion action of increasing area and decrease area of nozzle. Temperature is varying from inlet to outlet.

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Journal of Information and Computational Science ISSN: 1548-7741

4.2 Velocity in 45 degrees with pipe diameters of 0.018m, 0.016m

(a) (b) Fig.8 Velocity variation for different pipe diameters (a) 0.018m and (b) 0.016 From above figure 8. Contours of velocity are increased from inlet of 1.30m/s to 2.6m/s outlet. Velocity is increased due to diffusion action of increasing area and decrease area of nozzle. Velocity is uniform through the pipes because flow of gas in porous media consider as laminar. 4.3 Velocity in 60 degree with pipe diameters 0.02m 0.018m

(a) (b) Fig.8 Velocity variation for different pipe diameters (a) 0.018m and (b) 0.016 Contours of velocity is increased from inlet of 1.69m/s to 2.6m/s outlet. Velocity is increased due to diffusion action of increasing area and decrease area of nozzle. Velocity is uniform through the pipes because flow of gas in porous media consider as laminar. 4.4 Pressure in 45 degree with pipe diameters 0.02m 0.018m

(a) (b) Fig.9 Pressure variation for different pipe diameters (a) 0.018m and (b) 0.016 Volume 13 Issue 12 – 2020 www.joics.net 78

Journal of Information and Computational Science ISSN: 1548-7741

The contours of pressure, is decreased from inlet of 2.80 bar to - 1.12bar outlet. Pressure is decrease due to diffusion action of increasing area and decrease area of nozzle. Pressure is varying from inlet to outlet.

4.4 Pressure in 60 degree with pipe diameters 0.02m 0.018m

Fig.10 Pressure variation for different pipe diameters (a) 0.018m and (b) 0.016 the contours of pressure, is decreased from inlet of 2.53bar to --1.18e3 bar outlet. Pressure is decrease due to diffusion action of increasing area and decrease area of nozzle. Pressure is varying from inlet to outlet.

V CONCLUSIONS The following conclusions are made from the Fluid Flow (Fluent) simulation. • Flow simulation is carried out at constant mass flow rate of 0.305 kg/s exhaust gas with operating conditions 1.1 bar pressure and 833 K temperature • The special shaped catalytic converter with different cone angles and size of porous tubes allow the exhaust gas to flow freely without making any obstruction or blocking. Since the laminar flow technology is used, it helps to limit the back pressure to the minimum level resulting in better engine performance and fuel saving • Velocity, Pressure and Temperature results are compared for different cone angles of 45,60 and of two different diameters of 0.02 to 0.018m, showed velocity 54m/s, pressure 19.7 Pa and temperature 448 K against 0.02m mesh of low velocity 1.6m/s, pressure- 80 Pa and temperature 440 K. • It is observed different models performed in different manner: velocity profile is good in case of o.o18m mesh for 45 degree cone angle compared to 60 degree cone angle for better performance of converter REFERENCES [1] D. Chatterjee, O. Deutschmann, and J. Warnatz. Detailed surface reaction mechanism in a 3-way catalyst. Faraday Discussions, accepted for publication. [2] Ch.Indira Priyadarsini, Dr.P.Ushasri and Dr.M.V.S.Murali Krishna, ―Simulation on Catalytic Converter of Four Stroke Spark Ignition Engine‖, Conference on Recent Innovation in Mechanical Engineering 2014. [3] Ronald M Heck, Robert J Farrauto, ―Catalytic air pollution control : commercial technology‖, ISBN: 0442017820, New York, 1995. G.M. Lilley, W.J. Rainbird, A preliminary report on the design and performance of ducted windmills, Report 102, April 1956, College of Aeronautics, Cranfield, England. (Also available as Technical Report CIT ll9, 1957, Electrical Assoc., Leatherhead, England). Volume 13 Issue 12 – 2020 www.joics.net 79

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[4] G N Pontikakis, A M Stamatelos, ―Identification of catalytic converter kinetic model using a genetic algorithm approach‖, SAGE journals, 2004. [5] Michael G. Campbell., Edward P. Martin., "Substrate Selection for Diesel Catalyst" SAE 950372, 1995. [6] Chandler. G.R, Phillips. P.R, Wikinins. A.J.J, "Diesel Oxidation Catalyst for Light-Duty Vehicles" SAE paper 2000-01-1422. [7] Cathy Chung, Sivanandi Rajadurai and Larry GEE(1999), ―CFD Investigation of Thermal fluid flow and conversion characteristics of the catalytic converter‖ , SAE 1999-01-0462 [8] Olaf Deutschmann, Ju.Rgen Warnatz, ― Catalytic Combustion: State of the art and modeling needs‖, Second International Workshop on CHEMKIN in Combustion, Edinburgh/Scotland, July 30, 2000

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