The aluminum EGR cooler with pre-cooler integrated has been developed using CFD analysis. Because the temperature of exhaust gas in commercial CNG engines exceeds the temperature limit of EGR valve system, a new cooling strategy is required.
For the concept design of the cooler, efficiency is first evaluated by STAR-CCM+. Moreover, the efficiency of the cooler with external pre-cooler has been studied for the comparison. Conjugate heat transfer among the exhaust gas, engine coolant and EGR cooler is modeled. For considering wave EGR cooler fin effect, the simplified tube fin model is used. In detailed design stage of the cooler, the gas pressure loss across EGR cooler is minimized for increasing EGR flow rate. Also, temperatures of EGR cooler body and sealing cap are calculated. The temperature of EGR cooler body is mapped to Abaqus model and the TMF analysis is conducted. To increase durability of EGR cooler body, the position of sealing cap and the feature of flange connected to EGR pipe are optimized.