Three-Way Catalyst (TWC) physico-chemical model development in GT-SUITE

Nowadays, the Three-Way Catalyst (TWC) is the standard solution employed in the spark ignition (SI) internal combustion engines (ICEs) to reduce CO, HC, and NOx tailpipe emissions from vehicles, particularly those powered by gasoline. As regulations become more stringent and testing procedures more rigorous, the design of modern propulsion and after-treatment systems is evolving into complexity and as a consequence, the relevance of simulating the future behavior of a device is turning crucial. Therefore, it is necessary to develop numerical models embedding properly defined kinetic schemes, that can predict, robustly and accurately, the catalyst performances under various operating conditions. Compared to extensive experimental campaigns, these models are essential for reducing time and costs associated with the entire development process, from the concept phase to the calibration of the control system. Within this framework, this Master Thesis project aims to build and calibrate a 1-D simulation model of a TWC currently adopted by General Motors, utilizing GT-SUITE, a commercial multi-physics fluid-dynamic software from Gamma Technologies, LLC. This master thesis project begins with a comprehensive literature review to explore the operation of Three-Way Catalysts (TWC) and identify the best methods for calibration procedures. The review involves analyzing various studies to gain insights into TWC functionality and effective calibration techniques. Following the literature review, the next step is to analyze data provided by General Motors. This data includes results from tests conducted with the TWC installed directly on the emission pipeline. By examining these results, including the concentrations of various pollutants detected, we aim to better understand the parameters that need to be calibrated for accurate model adjustment. Given that the data originates from an engine-dyno test bench, it is crucial to carefully analyze each data channel. This detailed investigation helps to understand the working conditions of the internal combustion engine (ICE), as the pollutants produced are closely linked to ICE performance. Experimental data from emission test benches account for numerous factors influencing the results; therefore, a thorough examination of every detail is essential for accurate model calibration. Next, the thesis examines the preliminary GT-SUITE model provided by General Motors. The objective is to understand the construction of the model and determine which modifications are needed to better align it with the experimental data. This involves making adjustments to achieve the best possible fit between the model and the available data. Once these modifications are implemented, the calibration process will commence, incorporating all previous considerations. This final step will ensure that the model is accurately tuned based on the insights gained from the literature review, data analysis, and preliminary model adjustments. The future work in the calibration process will involve validating the 1-D model using real driving tests, including NEDC, WLTC, FTP, and RDE cycles. Among these, the RDE cycle is particularly valuable as it provides real-world tailpipe emissions data across a range of operating conditions, from idle to full load. This validation will ensure that the model reflects real-world emissions performance and can be used effectively for further analysis and optimization.