The PURItech product development team celebrated a big success just before Christmas:

The system DPFN++, which is equipped with an additional diesel fuel injection used for applications with low exhaust gas temperatures, has been successfully tested at the Technische Universitaet Graz. The system has been tested on a metro bus Mercedes Benz Citaro model with the emission class EURO III and exhaust gas emissions compared with and without PURItech DPFN++. What was not possible with a conventional particle filter with the PURItech DPFN it’s achievable: the reduction of carbon oxide (CO), Hydrocarbons (HC) and particulate matter (PM) is nowadays standard with closed particulate filters.

The Problem: Conventional particle filter increase emissions of NO2 and the NOx emissions remain constant

The tested PURItech system is able to do more. Nitrogen dioxide (NO2) and even Nitrogen oxides (NOx) are reduced significantly. With that, the filter retrofit problem is solved. The low NO2 limit in the ambient air, regulated in the EU since January 1, 2010, is not achievable in many cities along main street. In particular, vehicles with conventional filters are even increasing the NO2 emissions compared to vehicles without filters. With particulate filters, a reduction of particulate matter is achievable very efficiently. Also the NOx emissions are lower during the last years but the toxic NO2 emissions are significantly higher.

The solution is a combination with passive-active regeneration by PURItech

Due to the unique filter catalyst and the additional injection of diesel fuel to the pre-converter, not only the applicable range of the filter for low-temperature applications are possible, NOx and NO2 emissions are also reduced significantly. Reduction results for NOx are at 23% and NO2 at even 61% compared to engine baseline. Those results are even achieved without diesel fuel injection. If the injection is active, the emission reduction results are significantly higher. In mining and tunnel applications, the system is used very successfully because of the NO2 emissions, which are critical in this industry.

Until now NOx reductions have been achievable only with expensive SCR systems. With the PURItech system, the same results are possible with a system which is just a little higher than a passive system. Also the space requirements are not much more than with conventional systems.

Additionally, a SCR system requires exhaust gas temperatures at minimum 210 C – 220 C to work properly. At the tested low-temperature application, no ADBlue would be injected so that no NOx/NO2 reductions are measured. Customers who trust PURItech filter systems are on the safer side in order to comply with future requirements on NO2 decreasing exhaust gas after-treatment systems. PURItech systems reduce NO2 and, of course, particulate matter up to 99,9%.

The PURItech team is proud about its achievement, which reflects the excellent order situation.

DPFN+NC - Diesel Particle Filter System Brochure