Turbulence induced structures in Exhaust Gas Recirculation coolers to enhance thermal performance

•Structured surfaces strongly affected the thermal performance of EGR coolers.•Rib orientation profoundly affected the scale of turbulence with respect to inlet flow direction.•Lager grooves dimensions would result in improved thermal performance of EGR coolers.

While the utilization of Exhaust Gas Recirculation (EGR) coolers in diesel driven cars gathers pace, the degradation of the thermal performance of EGR coolers due to soot deposition becomes a matter of much concern. In-situ change of surface structure would potentially be a promising approach to stem the deposition process by changing local shear stresses for the same inlet exhaust gas velocity. The present study focuses on the deposition of soot particles as primary precursors in four structurally different EGR coolers. The investigated surfaces included grooved and straight/inclined ribbed plates as well as smooth flat plate for the sake of comparison. The experimental results showed that the ribbed plates particularly the straight ribbed plate improved the thermal performance of the EGR cooler by approximately 10% while the deposition rate reduced by 9% compared to the smooth flat plate. More importantly, the orientation of ribs with respect to the direction of gas inlet flow had a profound impact on the thermal performance due to the variation in the flow stream structure and its turbulence level. Similar results were not obtained for the grooved surface, due to rapid soot deposition of grooves.