Performance analysis of thermoacoustic plasma MHD generation

We develop a quasi-one-dimensional theoretical model describing the oscillatory plasma MHD conversion in a channel with parallel electrodes. Based on the model, a thermoacoustic plasma MHD generation system with a looped configuration is proposed and the characteristics of the operation of the system are investigated. Our results show that, for efficient oscillatory MHD generation, the channel dimension of the MHD duct should be much larger than the penetration depth (a proper Womersley number is above 100), otherwise the thermoacoustic effect will play a major role and consume considerable energy. Further, the electromagnetic induction parameter should be larger than 100S⋅T2/m, so that a majority of the kinetic energy of the oscillatory plasma can be harnessed for energy conversion. Moreover, a load ratio between 0.6 to 0.8 is suggested for the presented system, with which an efficiency above 20% can be achieved when the electromagnetic induction parameter is 500S⋅T2/m. In the optimal case, an efficiency of 24% can be obtained, with the corresponding output electricity of 1644 W. These results shed light on the feasibility of the closed-cycle MHD generation without any moving part, which endows the system with advantages of high reliability and long lifetime.