Effect of Flow Distribution on Emissions Performance of Catalytic Converters

1998 ◽  
Author(s):  
A. P. Martin ◽  
N. S. Will ◽  
A. Bordet ◽  
P. Cornet ◽  
C. Gondoin ◽  
...  
Keyword(s):  
Flow Distribution ◽  
Catalytic Converters

A Study of Inlet Flow Distortion Effects on Automotive Catalytic Converters

1991 ◽  
Vol 113 (3) ◽  
pp. 419-426 ◽  
Author(s):  
G. Bella ◽  
V. Rocco ◽  
M. Maggiore
Keyword(s):  
Flow Field ◽  
Flow Rate ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Catalytic Converters ◽  
Flow Distortion ◽  
Local Flow ◽  
Positive Effects ◽  
Local Boundary Condition

This paper will focus on the influence exerted by a nonuniform flow distribution at the inlet of oxidizers to catalytic converters on conversion efficiency evaluated channel by channel. To this aim the flow inside the whole domain, constituted by the exhaust manifold and an elliptic-cross-sectional pipe connecting it with the converter shell, is simulated by means of a three-dimensional fluid-dynamic viscous model. In this way, after assigning typical converter size and geometry (i.e., elliptic) the gas flow rate distribution can be described at its inlet surface, also varying the total mass flow rate. After calculating the flow field at converter inlet by means of a three-dimensional model, evaluation is possible of local flow distortion in comparison with the ideal conditions of constant velocity of the gas entering the honeycomb converter channels. The abovementioned distorted flow field is then assigned as a local boundary condition for another model, developed by the authors, able to describe, through a one-dimensional fluid-dynamic approach, the reacting flow into the converter channels. It was also shown that, due to this flow distortion, honeycomb converters are not uniformly exploited in terms of pollutants of different quantities to be converted in each channel (i.e., a nonuniform exploitation of all the metals coating the ceramic monolith). Finally, the positive effects determined by a diffuser upstream of the converter on flow distribution are analyzed.

Flow Distribution and Pressure Drop in Diffuser-Monolith Flows

1995 ◽  
Vol 117 (3) ◽  
pp. 362-368 ◽  
Author(s):  
J. Y. Kim ◽  
M.-C. Lai ◽  
P. Li ◽  
G. K. Chui
Keyword(s):  
Pressure Drop ◽  
Flow Distribution ◽  
Catalytic Converters ◽  
Duct Flow ◽  
Flow Uniformity ◽  
Trade Off ◽  
Diffuser Flow ◽  
Distribution Index ◽  
And Performance ◽  
Automotive Catalytic Converters

Most current automotive catalytic converters use diffusers to distribute the flow field inside the monolithic bricks where catalysis takes place. While the characteristics and performance of a simple diffuser flow are well documented, the influence of downstream brick resistance is not clear. In this paper, the trade-off between flow-uniformity and pressure drop of an axisymmetric automotive catalytic converters is studied numerically and experimentally for selected cases. The monolithic brick resistance is formulated from the pressure gradient of fully developed laminar duct-flow and corrected for the entrance effect. The monolithic brick downstream stabilizes the diffuser flows both physically and computationally. A distribution index was formulated to quantify the degree of nonuniformity in selected test cases. The test matrix covers a range of different diffuser angles and flow resistance (brick types). For simplicity, an axisymmetric geometry is chosen. Flow distribution within the monolith was found to depend strongly on diffuser performance, which is modified strongly by brick resistance. Pressure drop due to the headers and brick resistance and their relative roles is also identified. The implications of these data for converter design are discussed in terms of the trade-off between flow-uniformity and pressure drop.

Pressure-loss reduction and velocity-profile improvement in a catalytic converter by a flow deflector

2008 ◽  
Vol 222 (3) ◽  
pp. 455-467
Author(s):  
K Hirata ◽  
R Oda ◽  
S Tanaka ◽  
H Tanigawa ◽  
J Funaki
Keyword(s):  
Velocity Profile ◽  
Pressure Loss ◽  
Catalytic Converter ◽  
Flow Distribution ◽  
Catalytic Converters ◽  
Particle Image Velocimetry Technique ◽  
Pressure Drops ◽  
Flow Features ◽  
Flow Deflector ◽  
Exhaust Systems

In automobile exhaust systems, catalytic converters have become essential in reducing environmental pollution. However, the main components of catalytic converters produce large pressure drops in exhaust systems, which decrease engine power and increase fuel consumption. In addition to the need to reduce pressure loss, the flow passing through the catalytic substrate strate should be as uniform as possible, which provides a uniform thermal distribution and high catalytic conversion efficiency. The goal of the present study is simultaneously to reduce the pressure loss and to improve the flow distribution under spatial constraints. The authors herein propose new types of device and investigate their performances experimentally. Specifically, the possibilities of two types of flow deflector with a shell structure, which are placed inside the diffuser part of the catalytic converter in order to reduce flow separation, were investigated. In addition, using the particle image velocimetry technique and Pitot tube velocimetry, flow features such as the velocity profiles were elucidated. The tested converter has a standard cylindrical ceramic monolith substrate with channels of square cross-section. As a result, the two flow deflectors can reduce the pressure loss by 17 per cent and 22 per cent, compared with a no-deflector converter and can effectively improve the velocity profile.

scholarly journals Transient modelling of flow distribution in automotive catalytic converters

2004 ◽  
Vol 28 (9) ◽  
pp. 775-794 ◽  
Author(s):  
D.N. Tsinoglou ◽  
G.C. Koltsakis ◽  
D.K. Missirlis ◽  
K.J. Yakinthos
Keyword(s):  
Flow Distribution ◽  
Catalytic Converters ◽  
Automotive Catalytic Converters
Sign in / Sign up

Export Citation Format

Share Document