NH₃ Sensor Measurements in Different Engine Applications

In this study the exhaust gas ammonia (NH₃) concentrations from different exhaust sources were measured with an ammonia sensor. The aim of the study was to verify whether an NH₃ sensor has the potential to be used for monitoring and control purposes for SCR systems. Measurements were performed in laboratory and field conditions and comparison was made between Fourier Transform Infrared (FTIR) and Laser Diode Spectrometer (LDS) measurement techniques. With heavy-duty vehicles, a comparison between an LDS, FTIR and NH₃ sensor was performed on a heavy-duty chassis dynamometer. Measurements were performed at steady speeds using a World Harmonized Vehicle Cycle (WHVC) and Braunschweig test cycles. The urea injection rate for the SCR system was varied to generate different ammonia levels in the exhaust gas. NH₃ measurements with FTIR and NH₃ sensor were performed on large cruise ships using heavy fuel oil (HFO) and marine gas oil (MGO) as fuels. Also, long-term trials on two cruise ships were conducted using heavy fuel oil and low sulphur (S < 0.1%) residual fuel. The results indicate that the NH₃ sensor has the potential for being used in different applications for monitoring and controlling the SCR system. Measurement results with the sensor were in good correlation with LDS and FTIR techniques and, in dynamic measurements, the sensor response was very fast.