American Superconductor has designed, built, tested and delivered to the U.S. Navy's Office of Naval Research (ONR) a 5MW, 230‐RPM, 6‐pole high temperature superconductor (HTS) ship propulsion motor. The motor uses an air core armature winding and first generation HTS wire (BSCCO‐2223) field winding. The goal of the motor development project was to validate the technologies required to design and build larger HTS ship propulsion motors, as well as to develop a motor production process that streamlines development time and minimizes cost. A commercial variable frequency drive is used to power the motor. The HTS field winding is cooled with G‐M coolers with gaseous helium as the cooling medium in a closed cycle. The armature is cooled by Midel®. The motor was delivered to the U.S. Navy in July 2003 and met or exceeded requirements in operation (up to the facility's testing limit of 2.5MW). The motor demonstrated both full torque and full speed operation in separate tests.

The transverse velocity of the condensing phase during dehumidification is analogous to the transverse velocity at the wall when exercising boundary layer control by fluid extraction through a permeable wall. Wet and dry pressure drop and heat transfer rates are analyzed for correlation using boundary layer suction theory. Data are presented for flat-plate finned-tube heat exchangers during air heating and dehumidification operations and the data show a significant effect of transverse velocity correlated by the boundary layer suction formulation. The condensate film is considered isothermal in this analysis and the results indicate that an improved modeling of the condensate film is required. We find that the transverse velocity of the condensing phase has an important effect on transport phenomena during dehumidification and that the validity of the Chilton–Colburn heat and mass transfer analogy in describing dehumidification is supported by these results. It should be noted that the dry data form the beginning of a plate fin heat exchanger data base. The present data show the effect of tube diameter and, independently, fin density variation on the Colburn and friction factors with all other geometric parameters held invariant.

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The heat transfer and pressure drop performance of two types of finned tubes used in the air-conditioning industry are reported for 14 different bundle configurations. Twelve of these configurations contained a new type of finned tube called K-Y and two contained a more conventional pin fin. A unique characteristic of all these configurations is zero or negative fin-tip clearances. A comparison of the performance of these air-conditioning type finned tubes with negative fin-tip clearance is then made with the performance of typical air-cooled heat exchanger tubes used in the process and power industries. Both the heat transferred and the pressure drop are substantially higher with the air-conditioning configurations; the heat transfer coefficient is superior even to plain tubes. The very high heat transfer performance is more the result of the negative fin-tip clearance than the fin shape or type.

The high critical temperature and low thermal conductivity of the ceramic superconductor Y-Ba-Cu-0 were utilized to reduce the Joule heating and the heat leak in a vaporcooled current lead design of nominally 1-kA capacity. The lead consists of a lower superconducting part and an upper normal metal (copper) part. The superconducting part is an assembly of twenty rectangular bars fabricated from a composite of Y-Ba-Cu-0 and Ag (15% vol.) This part is designed to operate below the critical temperature of the ceramic superconductor. The copper part, consisting of twenty copper wires, extends outside of the cryostat and interfaces to the room temperature power supply. The lead was successfully tested in a liquid helium cryostat for currents up to 2 kA. At the optimum operating currents of 1.7 -1.8 kA, the helium boil-off measurements show a heat leak reduction of approximately 40% from the conventional designs. Details of the design, fabrication issues, and the testing are presented.