**8. Concluding remarks**

This chapter compiles and analyzes the main numerical approaches that have been proposed to predict and reproduce the fouling phenomenon that takes place inside the EGR system. Features of each option, its range of applicability, as well as their main strengths and weaknesses have been highlighted. The fouling prediction capabilities of each numerical approach have been analyzed in detail with the aim of reviewing the most relevant numerical approaches used in the study of the fouling process that occurs in the EGR system.

The stringent construction requirements of new EGR technologies and the development of new numerical techniques, and more particularly the use of computational fluid dynamics codes, have contributed to the creation of more sophisticated models that allow the simulation of the fouling phenomenon considering a large number of parameters and mechanisms. Nevertheless, the simulation of the deposit formation and evolution involves intricate matters, such as the particlefluid interaction, agglomerate formation, or the physicochemical reactions that take place inside the deposit, which make the fouling process a complex phenomenon that needs to be addressed coherently across all its parameters.

The information and knowledge about the numerical modeling of the fouling process in the EGR system collected in this study may help EGR designers and manufactures to improve and develop new vehicle emissions control techniques, which contribute to meet the Sustainable Development Goals.

#### **Acknowledgements**

The authors are grateful for the financial support from the Spanish Ministry of Economy, Industry, and Competitiveness through the ENE2017-87855-R project.

#### **Nomenclature**


models, and, although they provide detailed information about the fouling phe-

This chapter compiles and analyzes the main numerical approaches that have been proposed to predict and reproduce the fouling phenomenon that takes place inside the EGR system. Features of each option, its range of applicability, as well as their main strengths and weaknesses have been highlighted. The fouling prediction capabilities of each numerical approach have been analyzed in detail with the aim of reviewing the most relevant numerical approaches used in the study of the fouling

The stringent construction requirements of new EGR technologies and the development of new numerical techniques, and more particularly the use of computational fluid dynamics codes, have contributed to the creation of more sophisticated models that allow the simulation of the fouling phenomenon considering a large number of parameters and mechanisms. Nevertheless, the simulation of the deposit formation and evolution involves intricate matters, such as the particlefluid interaction, agglomerate formation, or the physicochemical reactions that take place inside the deposit, which make the fouling process a complex phenomenon

The information and knowledge about the numerical modeling of the fouling process in the EGR system collected in this study may help EGR designers and manufactures to improve and develop new vehicle emissions control techniques,

The authors are grateful for the financial support from the Spanish Ministry of Economy, Industry, and Competitiveness through the ENE2017-87855-R project.

that needs to be addressed coherently across all its parameters.

which contribute to meet the Sustainable Development Goals.

nomenon, they demand more computational resources.

*Environmental Issues and Sustainable Development*

**8. Concluding remarks**

**Acknowledgements**

**Nomenclature**

0-D zero-dimensional 1-D one-dimensional 2-D two-dimensional 3-D three-dimensional *A* surface area *AA* Antoine coefficient *BB* Antoine coefficient *CC* Antoine coefficient *C* soot concentration *c*<sup>0</sup><sup>5</sup> constant coefficients

*CD* drag coefficient

**346**

CFD computational fluid dynamics

*Cm* thermophoretic constant *Cs* thermophoretic constant *Ct* thermophoretic constant *DB* molecular diffusivity

*Cc* Stokes-Cunningham slip correction factor

process that occurs in the EGR system.



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