Performance of disk generators for open-cycle MHD power generation

Abstract

The performance characteristics of disk MHD generators are analyzed for the combustion products of a Western coal at typical baseload conditions. Three disk generator configurations—radial outflow, radial inflow, and radial inflow-outflow—are considered for both impulse and reaction modes of operation. It is shown for enthalpy extraction, generator isentropic efficiency, and electric fields to be sustained along the generator channel, that the reaction mode radial inflow configuration is preferable for the baseload disk generator. The radial inflow-outflow configuration, which is a combination of the inflow and outflow geometries, could attain higher performance than the radial inflow configuration with substantially reduced generator size. Comparisons of disk generators with linear generators show that the performance of the disk generator is comparable to that of the diagonal generator, while the magnet cost for the disk generator is expected to be less than for linear generators. In view of these results, together with the advantages associated with simple channel construction, it is concluded that the disk generator is a potentially effective alternative to linear generators for baseload power generation.