PRESSURE DROP AND HEAT TRANSFER OF CATALYZED DIESEL PARTICULATE FILTERS DUE TO CHANGES IN SOOT LOADING AND FLOW RATE

摘要

When soot particles are loaded in a diesel particulate filter, it causes increase in back pressure of the exhausl system. To minimize this pressure drop due to DPF, the filter needs to be regenerated after a certain amount of soot has been accumulated. It is crucial to estimate the correct amount of soot that has been accumulated by measuring the differentia] pressure. It is also important to understand changes in pressure drop due to flow rate variations of the exhaust gas, since the pressure drop would be influenced by the exhaust flow rate as well as the amount of soot. Furthermore, the heat transfei characteristics of the catalyzed diesel particulate filter (CDPF) are another major issue, as the filter is occasionally exposed to high temperature gas. This study presents the characteristics of pressure drop according to the variation of soot loading and the mass flow rate in CDPF. In addition, heat transfer characteristics in the filter was investigated when a high temperature gas flows into the CDPF. Tests were performed in several CDPF samples having varying amounts of catalyst coating. Experimental results indicate that rig-based experiments are useful in understanding the characteristics of pressure drop in the CDPF. In the cake filtration region, a pressure drop has a proportional relationship according to soot loading and mass flow rate. It was found that an increased catalyst coating may lead to enhanced convective heat transfer.