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The authors conduct detailed r–z two dimensional time dependent numerical simulations of a closed cycle disk MHD generator for various load conditions. The objective of this study is to compare the results of the newly performed detailed r–z two dimensional time dependent numerical simulations with those of the already performed quasi-one dimensional time dependent numerical simulations. In the calculations, the generator using cesium seeded helium plasma with 100 MW thermal input and 40 MW electrical output is assumed, and the extent from its subsonic nozzle to diffuser is considered as the analytical region. It is made clear that the two dimensional simulation results almost coincide with the quasi-one dimensional ones except for the high load resistance condition. The intermittent discharge phenomenon under high load resistance condition is simulated for the first time in the present study. This means that the quasi-one dimensional simulations are unreliable when the load resistance is high, indicating the necessity of the present simulations. [Copyright &y& Elsevier]

A new fossil fuel utilized high performance combined power generation system with liquefaction recovery of carbon dioxide is proposed. In the system, pure oxygen is used as the oxidant gas to prevent the mixture of nitrogen in the exhaust gas and to make the liquefaction recovery of carbon dioxide possible. A solid oxide fuel cell (SOFC) is selected as the topping cycle. The exhaust fuel gas of the SOFC is afterburned with its exhaust oxidant gas of pure oxygen, and the heat of the combustion gas is utilized in the bottoming cycle. A closed cycle MHD/noble gas turbine cycle is selected as the bottoming cycle because the temperature of the combustion gas reaches about 2300 K. It is made clear through detailed examination of the energy balance that the total thermal efficiency of the system using natural gas (methane) as the fuel reaches 63.66% (HHV) or 70.64% (LHV). This efficiency is very high for the system with carbon dioxide recovery. The proposed system, therefore, has excellent performance and is worth further research and development. [ABSTRACT FROM AUTHOR]

A power inversion and control system for a supersonic closed cycle disk MHD generator, using a current source PWM inverter, is considered, and its performance is confirmed through numerical simulations for a model system in which the MHD generator with 100 MW thermal input and 40 MW electrical output, using cesium seeded helium plasma, is connected to the electric power system, expressed by the infinite bus, via the power inversion and control system and the power transmission line. It is made clear that the system can stably and steadily transmit the nominal electric power from the MHD generator to the electric power system under the nominal operating condition. The system is robust for the change of the a.c. side voltage, and the nominal operation of the MHD generator can be kept, even in the case of voltage fluctuation. It is also made clear that the active and reactive power provided to the electric power system stably and steadily trace the change of their set values, indicating the excellent power control performance of the system. [Copyright &y& Elsevier]