Design Procedure for Robust Design of CV EGR Coolers Against Thermal Fatigue 2017-01-0135
Exhaust Gas Recirculation (EGR) is an effective technique for reducing NOx emissions in order to achieve the ever more stringent emissions standards. This system is widely used in commercial vehicle engines in which thermal loads and durability are a critical issue.
In addition, the development deadlines of the new engine generations are being considerably reduced, especially for validation test phase in which customers usually require robust parts for engine validation in the first stages of the project. Some of the most critical issues in this initial phases of program development are heavy boiling and thermal fatigue.
Consequently it has been necessary to develop a procedure for designing EGR coolers that are sufficiently robust against heavy boiling and thermal fatigue in a short period of time, even when the engine calibration is not finished and the working conditions of the EGR system are not completely defined.
This methodology describes how to use CFD and analytical tools for obtaining approximate temperature maps of the EGR cooler in a very short period of time in order to optimize the coolant distribution by ensuring minimum coolant velocities and avoiding heavy boiling. This calculations are focused on a thermal fatigue test definition that is based on experience and the available data of the engine, allowing to reduce drastically the development deadline while guaranteeing robustness and quality.