BMW have been working on hydrogen-powered vehicle for over 20 years. The BMW Hydrogen 7 is the result of long-term research activities that have continued for six generations. The BMW Hydrogen 7 is dual-fuel concept internal combustion engine, which runs on both hydrogen and gasoline. The engine is a V12, with a 6-liter displacement and output of 260hp. Hydrogen is stored in the liquefied phase using ultrahigh-insulation cryogenic storage.
The present status of the development of Bi2223 HTS wires and their applications is summarized. Bi2223 wire performance has been greatly improved by adopting the so-called “Controlled Over Pressure” technique. Not only the critical current, but also long wire availability is improved due to the 100 % density of the HTS portion. Further to progress in the area of applications, prototypes such as high-field magnets, ship propulsion motors and power cables are introduced. Also, future directions towards material and application development are proposed.
Part VI, the final part of this study, covers the multi-stage expansion cycle. The thermodynamic mechanism of the minimum attainable temperature is described by means of a single-stage expansion method. A simplified computer simulation model has been developed for the multi-stage expansion cycle. An example calculation for a two-stage Stirling cooler and GM-type pulse-tube cooler is performed. The effect of real gas properties and specific heat of the regenerator material are discussed, as well as operating conditions such as pressure ratio and frequency. The final section of this study discusses the Vuilleumier cycle, which is not widely utilized in the application field of cryocoolers. In the future, however, this method, in conjunction with a thermo-acoustic resonating system, might have some potential from the viewpoint of long life or low-cost coolers because of its simplicity.