Mapping of hydrocarbon condensation onset temperature and its sensitivity analysis for Exhaust Gas Recirculation (EGR) cooler

Exhaust Gas Recirculation (EGR) cooling technology is one of the key technologies of the engine to meet the Euro 7 emission standard. Nevertheless, the hydrocarbon (HC) condensation in the cooler leads to uncontrolled thermal-hydraulic performance, and the onset temperature of HC condensation is still debated, which is one of the obstacles to implementing the Euro 7 standard. Here, we first established a database of key parameters (carbon number, concentration, and pressure); then theoretically calculated the onset temperatures of various condensation types (wall condensation, heterogeneous nucleation, and homogeneous nucleation), plotted the entire map and verified its veracity; and finally, elucidated the contribution of each parameter through sensitivity analysis. The results show that (i) HC species are C12 to C25, from 25 to 1717 ppm concentrations, and pressures are from 1 to 4 bar. (ii) The map diagrams for the onset temperature of HC condensation have broad applicability and strong practicality. (iii) The temperature ranges of the onset of wall condensation, heterogeneous nucleation, and homogeneous nucleation are from 4 to 218 °C, from 1 to 209 °C, and from −6 to 195 °C, respectively. (iv) Carbon number has the most significant contribution, followed by HC concentration and pressure. The results can provide a valuable reference for more accurate EGR cooler design and management.