Mitigation of the Diesel Soot Deposition Effect on the Exhaust Gas Recirculation (EGR) Cooling Devices for Diesel Engines

An investigation was performed to characterize the effect of the short twisted-tape inserts on the performance of EGR cooling devices for diesel engine applications. The results showed that the addition of the twisted-tape insert reduced the soot deposition and the blockage of the entrance region observed in the cooling devices tested without inserts. The addition of the inserts improved the thermal performance of the cooling devices for lower mass flow rates per tube with a relatively intermediate penalty of the long-time pressure drop build-up. At high flow rates, there was only smaller improvement of the heat transfer and a larger pressure drop penalty was observed. The results suggested that the addition of short twisted-tape inserts could be used to improve some current under performing designs of cooling devices. Optimization in terms of the tape-to-tube length ratio, tube diameter, and number of tubes is required in future studies for higher potential EGR rates.