Numerical Simulation of a 2D Subsonic Constant Cross-Section MHD Generator and Investigating It’s Influence on Performance of Triple Combined Cycles

In this research, Magneto-Hydro-Dynamic subsonic flow in a MHD generator has been simulated and its effect on efficiency and power generation of a triple cycle has been investigated. A 2D constant cross-section Faraday channel with segmented electrodes was used as MHD generator. MHD flow was assumed steady and compressible with ideal five-wave model MHD equations. Navier-Stokes equations were solved with an implicit density based method and the Poisson equation was solved by electric potential method. The suggested triple cycle consists of an open-cycle MHD as a topping cycle, gas turbine as the middle generator and steam turbine as bottoming cycle. A MATLAB code consists of the thermodynamic relations, governing the triple cycle behavior has been developed to analyze the performance of the combined cycle base on the MHD generator. Results showed that for a constant cross-section subsonic MHD generator, the maximum enthalpy extraction can be achieved for Mach numbers between 0.3 and 0.4 and the magnetic field between 4 and 6 Tesla. The enthalpy extraction of the MHD generator at Mach number of 0.3 and magnetic field of 6 Tesla increases up to 12.27%. Besides the optimum efficiency of 63.59% is achieved compared to the combined cycle without MHD generator, which was estimated almost 40.89%.