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

1)研制了可应用于工业生产的实验室规模太阳能反应器，并对其锌/铁氧体两固相陶瓷两步水裂解太阳能制氢的性能进行了评价。两步水裂解包括：1)ZnFe_2O_4=Zn+2/ 3fe_3o_4 +2/ 3o_2的o_2释放步骤和2)Zn+2/ 3fe_3o_4 +4/3H_2O=ZnFe_2O_4+4/3H_2的H_2生成步骤。o_2的释放温度在1500℃左右，比Zn/ZnO体系低200 ~ 300℃。2)在Zn/铁氧体体系的基础上，我们找到了更可行的ZnO/ mn -铁氧体体系的两固相陶瓷，该陶瓷可以在1000℃左右的温度下进行0_2的释放。该温度（1000℃）是金属氧化物两步水裂解中释放o2的最低温度。该ZnO/ mn -铁氧体体系的太阳能反应器设计为重复两步操作，利用单相和两相之间的相变来生产更多的氢。在2001年11月于澳大利亚阿德莱德举行的国际太阳能大会上，介绍了ZnO/ mn -铁氧体体系的实验结果。在本次大会上，我们与本研究的国际合作成员在澳大利亚大学就太阳能反应堆进行了会议讨论。3)对日本东京工业大学（TIT）实验室规模的下射太阳能聚光系统进行了改进，通过将反射镜面积扩大两倍来提高聚光性能，并研究了聚焦像分布与聚光系统的关系。为开发一种具有日本特色的定日镜技术，对已生产的用于下射太阳能聚光系统的定日镜进行了重新设计，并提取了改进点。在此基础上，研究了ZnO/ mn -铁氧体系统的太阳能/化学能转换效率。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