Semi-empirical study based on numerical analysis for analyzing LP-EGR condensation phenomenon in the gasoline engine of a hybrid electric vehicle

This study focuses on condensation phenomena within a critical component, the low-pressure exhaust gas recirculation (LP-EGR) cooler. By combining experimental and computational techniques, we aimed to understand and predict condensation behavior under various operating conditions. A dynamometer test was conducted to identify the condensation issue and its location. Computational Fluid Dynamics (CFD) analysis was employed to visualize flow patterns and temperature distributions within the cooler. Coolant temperature was selected as the primary variable influencing condensation. Our findings revealed an inverse relationship between the LP-EGR rate and the amount of condensation. A lower LP-EGR rate led to increased condensation. At 2000 rpm and an EGR rate of 4.7 %, approximately 16.4 g of condensation was observed. Furthermore, CFD simulations predicted that at a coolant temperature of −17 °C, condensation could reach up to 55 g. Tube 4 in the cooler was identified as the most susceptible area due to prolonged residence time of low-temperature flow. Based on these results, we recommend implementing a flexible LP-EGR rate strategy to mitigate condensation issues, especially under cold operating conditions. This approach can help optimize engine performance and reduce emissions while minimizing the negative impacts of condensation.