Measurements of Flow Loss in Helical-Type Seawater MHD Power Generator

Abstract

Synopsis:To construct a calculation model of flow loss in a helical-type seawater magnetohydrodynamics (MHD) power generator, it is important to elucidate the effects of the rotation number, the pitch length and the inner diameter of the helical wall on the pressure distribution and flow loss. The pressure distribution and flow loss in experimental devices constructed to model generators with a helical wall made of polyvinyl chloride with an outer diameter of 100 mm, inner diameters of 10, 20 and 30 mm, pitch lengths of 30, 37.5 and 45 mm and rotation numbers of 3, 5 and 7 were measured systematically. The effect of the rotation number on flow loss was small at flow rates of 20 m 3 /h or less and relatively large at flow rates of 30 and 40 m 3 /h. The effect of the pitch length was small at flow rates of 20 m 3 /h or less and relatively large at flow rate of 28 m 3 /h. The effect of the inner diameter was small at flow rates of 20 m 3 /h or less and relatively large at flow rates of 30 and 34 m 3 /h. The pressure drops in the vicinity of the entrance and / or the exit were the main causes of the disagreement in the flow loss between the experimental and computed values. The equations for the coefficient of entrance flow loss and exit flow loss were modified on the basis of the experimental data.

Fundamental Study of Helical-Type Seawater MHD Power Generation with Partitioned Electrodes

“…In addition, the seawater MHD generator has the advantages of no mechanical parts and being maintenance-free as well as low loss and high efficiency in comparison with a conventional seawater turbine [1]. In seawater MHD generation, a new helical-type seawater MHD power generator using a solenoid superconducting magnet is an attractive renewable energy source that can be installed offshore [2][3][4][5][6][7]. So far, the experimental values of the electromotive force and output of the generator have been smaller than the calculated values [2,4,6].…”