The design and fabrication of a small MHD pump for liquid sodium circulation

Abstract

e linear annular magnetohydrodynamic (MHD) pump was designed for the purpose of transporting the electrically conducting liquid sodium that is used as a coolant in a Sodium cooled Fast Reactor (SFR) operating at high temperatures (over 550 °C). The MHD pump was designed by using an equivalent circuit method which is commonly employed to the design of the induction machines. The mathematical equations on the developing pressure and efficiency was found out by using Laithewaite's standard design formula. The main geometrical parameters for the design were the pump core length, the diameter of the pump and the annular gap size. The dominant electromagnetic variables were the input frequency, magnetic pole pitch and number, and coil turns. Especially, it was shown that the developing pressure and efficiency were maximized at the range of frequencies below the commercial value of 60 Hz. Also, the size of an annular gap was suitably selected considering the hydraulic frictional loss at the narrow annular channel. The P-Q characteristic was theoretically predicted according to the change of the input current, voltage and power. The functional and structural components of the pump consisted of the material compatible with the high temperature and chemical reactivity of the liquid sodium. The designed pump was predicted to have the nominal flowrate of 10 L/min and the developing pressure of 4 bar.