Adiabatic Efficiency and Joule Dissipation in Supersonic Faraday MHD Generator

Abstract

Adiabatic efficiency of aa supersonic Faraday MHD (magnetohydrodynamic) generator and its relation to Joule dissipation in the MHD channel were studied in a shock tube experiment. The adiabatic efficiency of 39.7% was obtained at the enthalpy extraction of 8.3%. A dissipation process, which reduces the adiabatic efficiency, is examined by evaluating loading parameters and entropy productions caused by the Joule dissipation. At low load resistances, large Faraday currents in the channel upstream cause extremely large Joule dissipation in both the main flow and the region near the electrodes. It is confirmed experimentally that a high loading parameter yields a high adiabatic efficiency because Joule dissipation is small throughout the MHD channel.