Effect of active and passive regeneration techniques for diesel particulate filters on nitrogen oxide and PM emissions

The emissions from diesel engines have been a growing concern in the United States and many other parts of the world. It has been the efforts of the Environmental Protection Agency (EPA) that has made diesel engines produce much lower emissions over the last few decades. The EPA has made regulations increasingly strict to the point after treatment devices are now needed to meet emission standards. After treatment devices are being designed for oxides of nitrogen, particulate matter, hydrocarbons, and carbon monoxide.A study was done at West Virginia University (WVU) in order to evaluate the effect of active and passive regeneration in diesel particulate filters (DPFs) on nitrogen dioxide (NO2) and particulate matter (PM) emissions. Six different test configurations were examined using a diesel particulate filter and diesel oxidation catalyst (DOC) combination. It was found that a diesel particulate filter could in fact reduce PM and NO2 simultaneously. The study also showed the negative effect of a DOC on the NO2 emissions and that the most successful NO2 reductions were produced from configurations only involving a DPF. The best results for NO2 reduction were recorded using an active regeneration DPF but passive regeneration could also be used to decrease NO2 in a less efficient manner.