Modeling and analysis of pumping cell of NOx sensor – Part II: NOx pumping cell

To improve the performance of the NOx sensor, a combined model based on the electrochemical model and the diffusion model is developed for the NOx pumping cell of the NOx sensor. Considering that a small amount of oxygen enters the third chamber and part of NO is decomposed in the second chamber, the reactions of both NO and oxygen at cathode are taken into account in the electrochemical model, and the diffusion model additionally takes the diffusion of oxygen and the decomposition of NO into consideration. To validate the model at different gas concentrations, the sensor is mounted on the designed test rig. Then, the simulation results are compared with experimental data from the test rig and good agreement is obtained. In addition, three key parameters in the model of the NOx pumping cell are analyzed. The values and changing trends of these three parameters are given in the paper.