Mathematical modelling of YSZ-based potentiometric gas sensors with oxide sensing electrodes: Part II: Complete and numerical models for analysis of sensor characteristics

A variety of the computer-model-based optimal design methodologies have been developed using deterministic approaches. The use of the most of deterministic approaches without a numerically implemented mathematical model of gas sensors can lead to an ineffective optimal design and poorly defined optimization criteria owing to the presence of errors in oversimplified mathematical description. In this article, a complete mathematical model of electrochemical gas sensors, represented as a system of partial differential equations of parabolic and hyperbolic types, as well as the algorithm of transfer from the complete model to models of specific sensors is discussed in details. Further, a mathematical model of yttria-stabilized zirconia (YSZ)-based gas sensors with oxide sensing electrodes (SEs) has been numerically implemented based on the finite difference method. One-dimensional simulations are presented over a range of parameters to investigate the effect of temperature and gas concentrations gradients at the SEs on the sensor performance. Both models together with the proposed algorithm provide a decision-making tool for better optimal design of the solid electrolyte gas sensors.