Nitrogen species measurement investigation using two different FTIR

Current diesel engine after-treatment systems, such as Selective Catalyst Reduction (SCR), use ammonia (NH3) to reduce the Oxides of Nitrogen (NOx) into Nitrogen (N2) and water; however, if the reaction between ammonia and NOx unbalance this can lead either ammonia or NOx being released into the environment. Ammonia is classified as dangerous compound for the environment; therefore, accurate measurement of ammonia is essential. Fourier Transform Infrared (FTIR) is one of the most common method used to measure raw emissions from engine exhaust pipes, due to its capability to measure multi-type emissions at the same time. However, not many FTIRs that can measure gas from engine exhaust, and most of them has different characteristics and specifications. These can affect the emission measurement from exhaust pipes and lead to uncertainties in meeting compliance demands. The work of this paper compares two FTIR that have different specifications. These FTIRs, have been compared under well controlled laboratory conditions. The concentration of ammonia and NOx from diesel engines has been measured under different engine load and speed. The ammonia readings from each FTIR are plotted into a graph and analysed, the results show that one of the FTIR produces a lower reading compare to the other FTIR. A Chemical Luminance Detector (CLD) was used to measure the NOx and then compared with both FTIRs. After analysed those dataset, the results clearly show the FTIR specification can affect the emission measurement from diesel engines exhaust.