Performance of an Annular Linear Induction Pump with Applications to Space Nuclear Power Systems

Results of performance testing of an annular linear induction pump are presented. The pump electromagneticallypumpsliquidmetal througha circuitspecially designedto allow for quantificationof the performance. Testing was conducted over a range of conditions, including frequencies of 33, 36, 39, and 60 Hz, liquid metal temperatures from 125 to 525 ◦ C, and input voltages from 5 to 120 V. Pump performance spanned a range of flow rates from roughly 0.16 to 5.7 L/s (2.5 to 90 gpm), and pressure head < 1t o 90 kPa (<0.145 to 13 psi). The maximum efficiency measured duringtestingwas slightlygreater than6%. Theefficiency was fairly insensitive to input frequency from 33 to 39 Hz, and was markedly lower at 60 Hz. In addition, the efficiency decreased as the NaK temperature was raised. The performance of the pump operating on a variable frequency drive providing 60 Hz power compared favorably with the same pump operating on 60 Hz power drawn directly from the electrical grid.