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Kitano Seiki Co., Tokyo University of Marine Science and Technology | Date: 2010-06-02

Problem to be Solved To provide a small, lightweight, cryo-rotary joint. Solution A joint includes a housing


Felder B.,Tokyo University of Marine Science and Technology | Miki M.,Tokyo University of Marine Science and Technology | Deng Z.,Tokyo University of Marine Science and Technology | Tsuzuki K.,Tokyo University of Marine Science and Technology | And 3 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2011

Temperature Superconductors (HTS) applied to rotating machines require an efficient cooling system. It is necessary to increase the maximum trapped flux density in the bulk HTS magnets and decrease the overall cooling time. In this paper, we added a gaseous helium phase to a condensed-neon closed-cycle thermosyphon. The latent heat of neon-film cooling is combined with helium's high thermal conductivity. Different mixture proportions were evaluated in terms of resistance to variable heat loads. More helium decreased the temperature variation of the evaporator. The mixture was then used to cool down a 30 kW-grade gadolinium-bulk HTS synchronous motor. The eight bulk HTS conductors of the rotor were cooled to 40 K in less than six hours. The application of this thermosyphon is envisioned for larger rotating machines. © 2011 IEEE.


Felder B.,Tokyo University of Marine Science and Technology | Miki M.,Tokyo University of Marine Science and Technology | Tsuzuki K.,Tokyo University of Marine Science and Technology | Izumi M.,Tokyo University of Marine Science and Technology | Hayakawa H.,Kitano Seiki Co.
Journal of Physics: Conference Series | Year: 2010

The axial-gap synchronous machine developed in our laboratory is based on Gd-bulk HTS field-pole magnets, able to trap a part of the magnetic flux they are submitted to when cooled down below T c. At the liquid nitrogen temperature, by the Pulsed-Field Magnetization (PFM), 1.04 T was trapped in 60 mm-diameter and 20 mm-thickness magnets, leading to an output power of the motor of 10 kW at 720 rpm. To enhance this performance, we have to increase the total amount of trapped flux in the bulk, the shortest way being to decrease the temperature of the bulk HTS. Thus, we focused on the improvement of the condensed-neon cooling system, a closed-cycle thermosyphon, so that it provided enough cooling power to lead the rotor plate enclosing the magnets to a low temperature. The present study implied coming out with a new fin-oriented design of the condensation chamber; hence, the numeric calculations and FEM software (ANSYS) heat transfer simulations were conducted for various shapes and positions of the fins. The trapezoidal design offering the best efficiency was then manufactured for testing in a heat-load test configuration, leading to cooling times divided by three and a maximum heat load endured of 55 W. © 2010 IOP Publishing Ltd.


Miki M.,Tokyo University of Marine Science and Technology | Felder B.,Tokyo University of Marine Science and Technology | Tsuzuki K.,Tokyo University of Marine Science and Technology | Deng Z.,Tokyo University of Marine Science and Technology | And 4 more authors.
IEEE Transactions on Applied Superconductivity | Year: 2011

A synchronous rotation study with eight field rotor pole of Gd123 bulks was performed with the axial-type motor. The field pole of Gd123 packs with and without doped amorphous magnetic particles Fe-B-Si-Nb-Cr-Cu (MP) were employed. Before and after the synchronous operation, the change of the trapped magnetic flux on the bulk was investigated at the operating temperature of 40 K. The observed decay of the trapped integrated flux on the surface of Gd123 packs after 5 hours synchronous rotation were 7.2% for the Gd123 pack without MP doping and 4.1% for the Gd123 bulk doped with MP. The present result indicates that the lowering operation temperature may be beneficial to avoid the AC loss. This also leads to another complementally conclusion that the employment of the condensed neon gas cooling system is a suitable choice from the viewpoint of practical applications of the HTS bulks in contrast to liquid nitrogen cooling. In addition, the Gd123 doped with MP alloy particles provide a practical magnetic flux trapping function at 40 K. © 2010 IEEE.


Zhou D.,Tokyo University of Marine Science and Technology | Izumi M.,Tokyo University of Marine Science and Technology | Miki M.,Tokyo University of Marine Science and Technology | Felder B.,Tokyo University of Marine Science and Technology | And 2 more authors.
Superconductor Science and Technology | Year: 2012

The paper contains a review of recent advancements in rotating machines with bulk high-temperature superconductors (HTS). The high critical current density of bulk HTS enables us to design rotating machines with a compact configuration in a practical scheme. The development of an axial-gap-type trapped flux synchronous rotating machine together with the systematic research works at the Tokyo University of Marine Science and Technology since 2001 are briefly introduced. Developments in bulk HTS rotating machines in other research groups are also summarized. The key issues of bulk HTS machines, including material progress of bulk HTS, insitu magnetization, and cooling together with AC loss at low-temperature operation are discussed. © 2012 IOP Publishing Ltd.

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