Thermal and acoustic performance of silencing heat exchanger for engine waste heat recovery

The integrated design of gas heat exchanger and after-treatment unit can reduce the size and weight of the engine waste heat recovery system, releasing the back pressure of exhaust gas and enhancing net benefit of the waste heat recovery system. In this study, we propose a silencing heat exchanger that integrates an exhaust heat exchanger with an impedance composite muffler in the post-treatment system, using metal foam material instead of the sound absorbing material in the impedance composite muffler. By adapting ANSYS Fluent and LMS Virtual.Lab, thermal simulation and acoustic simulation of the silencing heat exchanger were realized, and comparative analysis of the modified structure and the basic structure was carried out. The modified silencing heat exchanger was then designed and fabricated, and the thermal and acoustic performance were tested. The results show that the modified silencing heat exchanger can achieve improved heat transfer and flow performance, and more uniform temperature distribution at the hot side, simultaneously resulting in an 8.4% reduction in exhaust pressure drop. Even more, the improvement of silence effect in the middle and high frequency band is fairly obvious, and the overall transmission loss is 44.4% higher than that of the basic structure.

Automated summary

An integrated design of a silencing heat exchanger that merges an exhaust heat exchanger with an impedance composite muffler has been proposed in this study. By utilizing metal foam material instead of sound absorbing material, the modified silencing heat exchanger achieved improved heat transfer and flow performance, as well as enhanced silence effect in the middle and high frequency band. The overall transmission loss was found to be 44.4% higher than the basic structure, with an 8.4% reduction in exhaust pressure drop.