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A new tool for SCR (selective catalytic reduction) testing is developed. This side stream test bench has an advantage to test smaller catalysts with a proper exhaust. The exhaust mass flow and temperature are adjustable. A control program is developed to adjust and save the needed parameters. NOx sensors are utilized in the test bench to measure the levels upstream and downstream of SCR reactor. In this study one SCR with a volume of 40.5 dm3 is tested with exhaust flows ranging from 400 to 600 kg/h and exhaust temperatures from 280 to 360°C. The tests are conducted using exhaust gas from a medium-speed diesel engine running on heavy fuel oil. A decrease from 75% to 99% (depending on test conditions) was observed in NOx over the catalyst. In addition HC and PM were found to decrease while CO was increased over the catalyst. The controlling of exhaust flow and temperature with the test bench succeeded with only minor errors.

State-of-art light duty diesel vehicles and heavy duty diesel engines are utilized in studying the effect of a novel particle oxidation catalyst (POC®) on particle emission. In addition to the regulated particulate matter (PM) emission measurement, a real time mass emission and particle number size distribution measurements are utilized in testing. The results show that the particle oxidation catalyst can have a significant decreasing effect on the diesel exhaust particle emissions. For example, in light duty applications PM reductions of 55-61% were achieved over the New European Driving Cycle (NEDC) when using a POC of same size as the engine volume. The usage of a DOC in combination with the POC ensures proper regeneration of the POC substrate. The size distribution measurements revealed that the particle number collection efficiency for smaller particles i.e. the nanoparticles was very high, being close to 100 %.

To reach close to zero tailpipe NOx emissions, a double-SCR (selective catalytic reduction) system is proposed. In that, the first SCR unit would be placed upstream of the diesel particulate filter (DPF) and the second SCR unit downstream of DPF. This study focused on the experiments of the first SCR unit. The experiments were conducted utilizing a new, 4.4-liter heavy duty diesel engine that was connected to a research facility for studying after-treatment systems in controlled environment. Three different SCR’s: a vanadium-based SCR (V-SCR), a copper-based SCR (Cu-SCR) and a vanadium-based SCR including an ammonia slip catalyst (V-SCR+ASC) were studied. Studies were done at different exhaust temperatures from 215°C to 350°C. Emissions of NO, NO2, NH3, N2O, CO, CO2 and hydrocarbons were measured by FTIR. Particulate emissions (PM, PN) were studied as a part of the experiments. The results showed that the three SCR units performed differently.