Influence of working fluid characteristics on the performance of a liquid metal magnetohydrodynamic generator

We compare the electrical performance and fluid phenomena of a liquid metal magnetohydrodynamic (LMMHD) power generator equipping electrodes with a finite electrical conductivity by using four different working fluids: mercury, NaK78, Galinstan and U-alloy47. Three-dimensional unsteady numerical simulations of turbulent duct flows under a non-uniform magnetic field are carried out. The profiles of the Hartmann layer and the wall-jet flows with M-shaped mean streamwise velocity are varied in accordance with the interaction parameter, which diff ers for each working fluid. A large interaction parameter decreases the wall friction loss and improves electrical efficiency. The finite electrical conductivity of electrode causes Joule loss and leads to a deterioration of efficiency. These results lead to the conclusion that a liquid metal with a high interaction parameter and a low electrical conductivity for reducing the electrical conductivity ratio of the fluid to electrodes will yield high electrical efficiency. © 2014 The Institute of Electrical Engineers of Japan.