Development of Closed Loop Emissions Control for Use in Dispatchable, Distributed Generation Systems using a Low Cost, State-of-the-Art, Solid-State Nitric Oxide Sensor

Two commercially-available solid-state sensors, both capable of measuring nitric oxide and oxygen content in the exhaust of diesel automotive systems, were utilized in the present study to determine their potential as an inexpensive alternative to traditional continuous emission monitoring systems for distributed generation (DG) deployments. In order to assess their performance and real-time measurement capabilities, an extensive data acquisition network was developed to compare signals against an established reference instrument (Horiba PG-350) over an extended period of six to eight months. An existing experimental testbed, a 60 kW Capstone Gas Turbine engine, was utilized as the representative DG system in this study, and an exhaust test section was designed and fabricated. Three sensors of the two commercial brands were selected to measure the deviation among individual signals. After the measurement period was conducted, it was found within a 99% confidence interval or greater, the NTK sensor performed better in three of five measured sensor characteristics, specifically with respect to LDL, Accuracy, and Lag-Time and Rise-Time. An emissions map was then generated using a statistically-designed study in order to find the operating parameters of the engine that produce the lowest nitric oxide and carbon monoxide emissions. Using these results, a control algorithm was developed and demonstrated, capable of incorporating the NTK sensor signals, to allow the engine to adjust its performance to reduce nitric oxide emissions in real-time and at all operating conditions