Performance of coal-fired MHD generators with large leakage current

Abstract

The objective of the present paper is, through numerical analyses, to study the performance of coal-fired MHD generators which suffer from large leakage current. Three channels are examined, of which the scale varies from experimental to pilot-plant size. The MHD channel and external circuits are simultaneously analysed, where a 2-D equivalent circuit method is applied for the electrodynamics and the gasdynamical behaviour is treated with a time-dependent 1-D approximation. The following results are obtained: (1) the overall channel performance predicted with the present model shows excellent agreement with the experimental data for medium and large experimental channels; (2) the leakage current becomes about 70 A for a channel with about 500 kW output, about 150 A for a channel with about 1.5 MW output, and about 200 A for a channel with about 10 MW output; (3) the loss due to slag leakage becomes about 30% of generated power for the CDIF channel and 20% for the generator of 10 MWe.