Exhaust Gas Regeneration System Design in Diesel Particulate Filter
No Thumbnail Available
Date
2015-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
In this study the diesel vehicle engine exhausts emissions, particularly Diesel Particulate Matter
and its impact on health and environment is discussed briefly. The filtration method used to
removes this particulate matter from diesel exhaust gases is using wall flow diesel particulate
filter through physical filtration. The filter designed for this application has a honeycomb
structure with long parallel flow channels and the opposite ends of adjacent channels are
alternatively capped, forcing gas to flow through porous side walls leaving soot behind on the
surface of the walls that would result in an adverse impact on engine performance.
Therefore the Diesel particulate filter regeneration system strategy (passive type), which
promotes the oxidation of carbon soot trapped in diesel particulate filter under normal engine
operation condition is applied in this study. This is achieved by catalyst coating on the filter cell
membrane to facilitate the soot trap combustion. in addition, Filter design parameters like filter
size and filter cell configuration which is responsible for the save regeneration are identified.
The mass flow rate of Diesel Particulate Matter Emission from diesel vehicle engine under
different operation condition (speed and loading) is considered by using weighting factor for
each operation point. Mass based particulate matter emission from diesel engine obtained in this
study is 36.01 (g/hr). for filter with 80% ,85% ,90% filtration efficiency of DPF: the Mass of
PM released to atmosphere in (g/bkw.hr) are 0.082, 0.062, 0.041 respectively, where the Europe
PM emission limit standards is achieved above 85% of filtration efficiency . The pressure drop
across Diesel Particulate Filter is predicted (2.81kpa) using soot layer thickness model.
Finally, regeneration behavior of diesel particulate filter using comsol multi physics by coupling
the exhaust gas flow(maximum flow velocity 4.2m/s),Particulate matter concentration
distribution in DPF model [maximum 12.5 mil (mol/m3) and 5mil(mol/m3) ]and the filter wall
temperature distribution(500 and 705 in K) due to soot trap oxidation reaction in DPF. From
the passive regeneration system applied the catalyst coated on the filter porous membrane
initiates the burning-off particulate matter in filter channel , reduces the oxidation temperature of
soot trap and keeps clean the diesel particulate filters under normal engine operation condition.
Description
Keywords
Mechanical design Stream