Low Temperature Active Regeneration of Soot Using Hydrogen in a Multi-Channel Catalyzed DPF 2010-01-0562
Diesel particulate filter (DPF) systems are being used to reduce
the particulate matter emissions of diesel vehicles. The DPF should
be regenerated after certain driving hours or distance to eliminate
soot in the filter. The most widely used method is active
regeneration with oxygen at 550~650°C. Fuel penalty occurs when the
exhaust gas temperature is increased. The low temperature oxidation
technique is needed to reduce fuel consumption.
In this study, we found that hydrogen could be used to decrease
the PM oxidation temperature significantly on a catalyzed DPF
(CDPF). The oxidation characteristics of PM with hydrogen supplied
to CDPF were studied using a partial flow system. The partial flow
system was used to control temperature and a flow rate
independently. The CDPF was coated with Pt/Al₂O₃ 25g/ft₃, and a
multi-channel CDPF (MC CDPF) with a square cross section of 1.65 cm
width and length of 10 cm was used.
Firstly, a hydrogen oxidation was tested for DPFs with and
without a catalyst. The oxygen concentration was fixed at 10%, and
hydrogen concentration was changed from 2% to 8%. For the DPF
without a catalyst, there was no significant hydrogen oxidation
below 300°C. However for the CDPF, the hydrogen oxidation started
actively over 120°C.
Secondly, soot regeneration experiments were performed to
investigate hydrogen exothermic reaction effects on soot oxidation
in a CDPF. Prior to perform oxidation experiments, PM was collected
about 8 g/L at the CDPF with a engine speed of 1500 rpm and BMEP of
8 bar. Also, partial flow temperature of 200°C was used to minimize
the NO₂ passive regeneration effect. The test was carried out with
a wide range of temperatures and hydrogen concentrations. Soot
oxidation in the CDPF started when H₂ concentration was 3% and the
temperature was as low as 180°C. Regeneration became faster when H₂
concentration was higher.