Svetlana M. Zemskova

Sensors for Environmental Compliance of Diesel Engines

The environmental impact of pollutants such as “acid rain” gases (NO, NO2, SO2, etc.) and “green house” components (CO, CO2, non-methane hydrocarbons NMHC) from diesel-powered machines are of great importance for sustainable growth. Significant efforts have been made by industry, government and universities regarding the design and implementation of advanced engine concepts as well as the associated aftertreatment systems to reduce emissions. However, the development of sensor technologies in these areas has not been addressed accordingly. Robust sensor technologies capable of detecting various gas species simultaneously are of great value for the diesel engine’s feedback control and subsequent optimization of the entire engineaftertreatment system. On-board monitoring sensors are also required by Environmental Protecting Agency. Our study examined various chemical gas sensors technologies through laboratory bench tests utilizing simulated diesel engine exhaust conditions. High temperature solid-state electrochemical sensors as well as heated metal oxide semiconductor sensors were tested and the results are presented. It was observed that the major issue for either technology was cross-sensitivity of the sensors when exposed to a very complex gas mixture such as diesel engine exhaust gas. The working principle of the current electrochemical NOx sensors (1) involves the electrochemical decomposition of NOx into nitrogen and oxy-anions: