Homogenization of Dimpled Tube and Its Application to Structural Integrity Evaluation for a Dimple-type EGR Cooler using FEM

摘要

Conventional EGR (exhaust gas recirculation) cooling systems have been used in automobile diesel engine to reduce environmental pollutants such as nitrous oxide (NOx), carbon oxide (COx) and particulate matter (PM). However, an EGR cooler has low heat-exchange efficiency. In this study, to improve the heat-exchange efficiency, a dimple-type EGR cooler was considered. A heat-exchange tube inside the dimple-type EGR cooler has numerous dimples on its surface for enlarging net heat transfer area. Numerical approach using the three dimensional finite element method was carried out to evaluate the structural integrity of the dimple-type EGR cooler that is subjected to thermal, pressure-related. In particular, the equivalent elastic and shear moduli and the equivalent thermal conductivity were calculated via the homogenization method to simplify finite element modeling and reduce computational costs. The dimpled tube was modeled as a flat tube without dimples. Finally, a prototype of the dimple type EGR cooler was developed and its high heat-exchange efficiency was evaluated by an experimental approaches. This finite element scheme can be used efficiently for developing a prototype of automobile EGR coolers.