Study on Solar Hydrogen Production using Concentrated-Solar-Heat Reactive Ceramics

1)研制了一种可实际应用于工业技术的实验室规模的太阳能反应堆，并对其用于锌/铁氧体系双固相陶瓷二步分水制氢的性能进行了评价。两步析水包括：1)锌铁氧体体系的析氧步骤和2)锌+2/3Fe_3O_4+4/3H_2O=锌铁氧体体系的制氢步骤。析氧温度在1500℃左右，比锌/锌体系低200-300℃。它可以在1000℃左右的温度下进行O2释放步骤。这一温度(1000℃)是金属氧化物两步分水的O2释放步骤的最低温度。这种锌锰铁氧体系统的太阳能电抗器设计为重复太阳能HY-…的两步操作。利用单相和两相之间的相变来生产更多的液氮。本文介绍了2001年11月在澳大利亚阿德莱德举行的国际太阳能大会上有关氧化锌/锰铁氧体系统的实验结果。在这次大会上，我们与澳大利亚大学这项研究的国际合作成员举行了一次会议，讨论了太阳能反应堆。3)对在东京工业大学制造的实验室规模的束下式太阳能聚光系统进行了改造，通过将反射镜面积扩大一倍来提高聚光性能，并研究了聚焦像分布与聚光系统的关系。为了开发日本独创的定日镜技术，对原用于聚束式太阳能集热系统的定日镜进行了重新设计，并提出了改进之处。利用改进后的束下式太阳能聚光系统，对ZnO/Mn铁氧体系统的太阳能/化学能转换效率进行了测试。较少

1)A laboratory-scale solar reactor which could be practically applicable for industrial technology was fabricated and its performance for solar hydrogen production by two-step water splitting using the two-solid-phase ceramics with the Zn/ferrite system was evaluated. The two-step water splitting consists of 1) the O_2-releasing step of ZnFe_2O_4=Zn+2/3Fe_3O_4+2/3O_2 and 2) the H_2 production step of Zn+2/3Fe_3O_4+4/3H_2O=ZnFe_2O_4+4/3H_2. The temperature for the O_2-releasing step is around 1500℃, which is lower by about 200-300℃ than for the Zn/ZnO system.2)Based on the Zn/ferrite system, we have found out more feasible two-solid-phase ceramics with ZnO/Mn-ferrite system, which can be operated at temperatures around 1000℃ for the 0_2-releasing step. This temperature (1000℃) is the lowest for the 0_2-releasing step of the two-step water splitting using metal oxides. The solar reactor for this ZnO/Mn-ferrite system was designed to be operated by repetition of the two-steps for solar hy … More drogen production using the phase transition between mono phase and two phases. The paper on the experimental results concerning the ZnO/Mn-ferrite system was presented at the International Solar Energy Congress, which was held at Adelaide (Australia) in Nov.2001. At this congress, we had a meeting to discuss on the solar reactor with the international collaboration members of this study at the Australia University.3)The beam-down solar concentrating system, which had been fabricated at TIT (Tokyo Institute of Technology) in laboratory scale, was modified to improve the concentrating performance by expanding reflection mirror area by two-times, and the relationship between the focus image distribution and concentrating system was examined. To develop an original technology belonging to Japan for heliostat, the heliostat which had been made to be used for the beam-down solar concentrating system was redesigned, and the improvement points were extracted. With those improved beam-down solar concentrating system, ZnO/Mn-ferrite system was examined for the solar/chemical energy conversion efficiency. Less