Design of two-stage thermoacoustic stirling engine coupled with push-pull linear alternator for waste heat recovery

Thermoacoustics is suitable technology for recovering waste heat and generating electricity. In this paper, a novel thermoacoustic electricity generator using a push-pull linear alternator is proposed. It is aimed to recover part of the internal combustion engine exhaust waste heat and produce useful electricity. It consists of two half wave length identical stages and a linear alternator connected in between them. The physically identical stages produce identical wave halves with acoustic pressure out of phase. The availability of two points having the same pressure amplitude out of phase provides the opportunity to connect the linear alternator to two points in each stage to run the alternator in a "push and pull" mode. The proposed engine is able to produce more than 138.4W of electricity at thermal-to-electrical efficiency of 25.1% equivalent to a fraction of Carnot efficiency of 45.1% while using helium pressurized at 40 bar.