## 5 Conclusions  
The discussed numerical analysis consists of a preliminary investigation into the adoption of an innovative POCS as a pre-catalyst for the ATS of a gasoline engine. The effects related to the induced pressure drop on the engine performances were investigated. The designed structure has been further integrated with an electrical circuit to exploit the  
Figure 21: Cold start assessment: HC percentage abatement comparison. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Pollutant** & CO & NO & HC \\ \hline
**\% Reduction** & 26.9 & 25.5 & 14.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Tail-pipe pollutants cumulative emissions. joule heating effects and to achieve an EHC behavior. The main findings of the work are discussed hereafter. * A dedicated simulation campaign was carried out to characterize the fluid-dynamic performances of the designed POCS. A combination of the 3D and 1D CFD analysis provided a clear assessment of the influence of the POCS-induced pressure drop on the engine performances. Despite the achieved results showing a non-negligible impact, one consisting of a maximum reduction in the brake power and an efficiency of 14.8 and 8.3%, respectively, the beneficial aspects of the EHC-POCS equipment could make up for the observed limitations. * The application of the Joule heating on the designed POCS was studied. A parametric analysis was performed, as a function of the applied potential difference. The obtained results show that the POCS material limit temperature can be achieved if the heating strategy relies on high potential differences and long heating time. Exploiting the parametric analysis, a dedicated heating strategy has been formulated and the assessment of the equipment of EHC-POCS in a realistic exhaust line was performed. The transient response of the ATS and the pollutants' conversion efficiencies were monitored when the overall system is subjected to simplified cold start conditions. As a consequence of the fluid-POCS interaction, the electrical heating application is such that higher exhaust gas temperatures were registered in the first phases of the thermal transient. The achieved energy levels are such that the catalytic reaction of the pre-catalyst can be activated. As a result, significant improvements in the pollutant abatement in the early phases of the cold start were obtained. However, with respect to a traditional EHC application, no significant improvements were obtained in terms of the light-off time of the standard catalyst. Furthermore, once the heating strategy was switched off, the POCS thermal inertia was responsible for a reduction in the exhaust gas temperatures and a lower catalytic activity (for the slow HC) was registered. * Overall, the designed EHC-POCS showed a promising behavior as a pre-catalyst to be equipped for advanced emission controls. Further improvements could be achieved with the definition of an ad hoc heating strategy, which could be dynamically activated as a function of temperature measurements, or through different POCS design principles, in order to reach an optimal trade-off between the required electrical power and the achieved temperatures. In addition, the exhaust line location in which the POCS structures are equipped could be significant. Moving the EHC-POCS near the standard ATS catalyst could reduce the exchanged heat power with the exhaust manifolds and significantly improve the beneficial effects associated with an early catalyst light-off. Finally, further studies are required to investigate the application of the EHC-POCS as a function of realistic cold start conditions and dedicated heating strategies. Conceptualization, L.B., A.D.T., G.M. and A.O. ; Methodology, L.B., A.D.T., G.M. and A.O. ; Software, L.B., A.D.T. and G.M. ; Validation, L.B., A.D.T. and G.M. ; Writing--original draft, L.B. ; Writing--review & editing, A.D.T., G.M. and A.O. ; Supervision, A.D.T., G.M. and A.O. All authors have read and agreed to the published version of the manuscript. This research received no external funding.