Investigating the effect of channel angle of a subsonic MHD (Magneto-Hydro-Dynamic) generator on optimum efficiency of a triple combined cycle

• Subsonic flow in a Magneto-Hydro-Dynamic generator has been simulated.
• A code was developed to analyze the performance of a combined cycle based on MHD.
• The effect of the MHD on efficiency of a triple cycle has been investigated.
• By increasing the MHD channel angle to 2.85°, the power of the MHD has tripled.
• The efficiency of the combined cycle increased significantly using the MHD generator.

In this research, subsonic flow in a MHD (Magneto-Hydro-Dynamic) generator has been simulated and its influence on efficiency and power generation of a triple combined cycle has been investigated. A 2D variable cross-section Faraday channel with segmented electrodes was utilized as a MHD generator model. MHD flow assumed to be ideal with low magnetic Reynolds number. The proposed triple cycle consists of an open MHD channel as a topping cycle, a gas turbine as a middle generator and a steam turbine as a bottoming cycle. A code including the equations, governing the triple cycle behavior, has been developed to analyze the performance of the combined cycle based on MHD generator. The optimum efficiency of 71.32% was attained for the triple cycle that is obviously greater than the efficiency of a combined cycle without MHD generator which was estimated to be 40.89%. Also the maximum net power output of 42.9 MW was obtained by the triple cycle based on a diverging MHD generator with 5.7° diverging angle.