Recent progress in fuel cell technology development for automotive application urges the need of an appropriate fuel for the next generation of cars. There has a basic consensus emerged within the engineering community and the environmentalists that hydrogen as an energy carrier should be the successor of fossil fuel derivates for both the new fuel cell vehicles as well as for the conventional internal combustion engines. On a gravimetric basis, hydrogen is an excellent energy carrier and when used in a fuel cell the only tailpipe emission is water. As the hydrogen gas density is very poor at ambient conditions, liquid hydrogen has become of great interest for automotive application. Consequently, a new infrastructure should provide liquid hydrogen at the pump for refuelling purposes. In regard of economically viable gas transportation and bulk storage at the refuelling station there are significant advantages using liquid hydrogen. A future scenario is likely to be realized by a liquid hydrogen supply system dispensing the gas in liquid and compressed form at the refuelling station.
Pulse-field magnetization (PFM) has been investigated for a bulk Sm-Ba-Cu-O superconductor cryo-cooled at 20 - 40 K using pulse magnetic fields Bex of 3.83 - 6.07 T. The temperature rise ΔT after applying the pulse fields increases as the bulk superconductor's initial temperature Ts decreases and as the applied field Bex increases. The generated heat Q, estimated using ΔT and the specific heat C of the bulk superconductor, decreases with decreasing Ts for lower Bex (=3.83 T), but increases with decreasing Ts for higher Bex (≥5.53 T). There is a slight increase in the pinning loss Qp determined from the magnetization M vs the applied field μ0Ha hysteresis curve at a lower Ts. These results can be explained by the increase in pinning force Fp at lower temperatures. The lowering of Ts is one of the promising approaches for enhancing trapped field BTP using PFM.
We investigated the effect of BaCeO3 addition on the superconducting properties of melt-textured YBa2Cu3O7-δ (Y123) bulk materials. Bulk superconductors with various compositions of Y123 + xBaCeO3 (x = 0.05-0.5) were fabricated by melt-processing in air. BaCeO3 particles of 1-2 μm in diameter were dispersed in the Y123 matrix phase. The addition of a small amount of Pt was effective for improving the Tc and Jc values. The Jc in the low field region increased as the amount of BaCeO3 for the sample was increased with x = 0.05-0.4. This indicates that BaCeO3 can function as effective artificial pinning center like Y2BaCuO5 particles in conventional melt-textured Y-Ba-Cu-O bulk materials.