Evaluation of a Novel Quadruple Combined Cycle With the Magnetohydrodynamic Generator Based on 6E Analysis

Abstract

Abstract The generation of the electric power through magnetohydrodynamic (MHD) is one of the most advanced high-temperature energy conversions as it directly turns the heat into electricity. In this study, a quadruple cycle with a MHD generator was considered as the upstream cycle, a Brayton cycle was taken as the middle cycle through heating, and an organic Rankine cycle and steam cycle were regarded as the downstream cycles using the heat loss of the MHD generator and gas turbine, respectively. Energy, exergy, exergoeconomic, exergoenvironmental, emergoeconomic, and emergoenvironmental (6E) analyses were done in the proposed system simultaneously for the first time. In addition, advanced exergy, exergoeconomic, and exergoenvironmental analyses were performed for the proposed system to show the effect of irreversibility accurately and deeply. Despite the slight difference between the results of the emergoeconomic and emergoenvironmental sector with the exergoeconomic and exergoenvironmental sector, the obtained qualitative results were very similar showing that the emergoeconomic and emergoenvironmental analyses can be proper alternatives to the conventional exergoeconomic and exergoenvironmental analyses. The temperature of the heat source is one of the most important criteria for fluid selection in the organic Rankine cycles. Five organic fluids were selected and evaluated according to the desired hot source temperature for the Rankine organic cycle (262 °C). The results showed that the R141b with energy and efficiency of 15.25 and 58.05%, respectively, had the best thermodynamic and exergy performance with the least amount of total costs using this fluid.