9860633 This Small Business Innovation Research Phase I project addresses the fluid dynamics of cryogenic helium gas in the rotating reference frame. The objective is to enable the development of refrigeration equipment which will have application in commercial high efficiency motors. American Superconductor Corporation (ASC) is a participant in a U.S. Department of Energy (DOE) program to develop ultra efficient electric motors using rotating high temperature superconductor (HTS) field windings. In these motors, it is desired to utilize refrigerators in the rotor to simplify the system and reduce the thermal losses associated with the rotating to stationary thermal interface. Rotation of the cryocooler is anticipated to be difficult due to secondary flows which will develop in packed bed regenerators under centrifugal acceleration. These secondary flows tend to thermally short circuit the packed bed and reduce the efficiency of the refrigeration cycle. In Phase I of this program it is proposed to analytically model the transport phenomena and to quantitatively measure the convective heat flux in packed beds as a function of centrifugal acceleration. This measurement would take place in an existing ASC facility. In Phase II we propose to test complete refrigerator subsystems under centrifugal acceleration. This project addresses a key technology for the commercialization of HTS motor technology. The ultra efficient motor should directly compete with induction motors and industry acceptance of this energy efficient technology can only be achieved with a highly reliable and efficient refrigeration system as the proposed rotating cryocooler.
