聚光太阳能与甲烷热化学互补的机理研究

This project breaks through the general thinking that efficient high-temperature thermal cycle must require for high-temperature collected solar heat, takes solar thermochemical power generation system as its research topic, from an interdisciplinary perspective of concentrated solar energy, chemical reactions and thermodynamic cycles, explores the core scientific questions including solar thermochemical hybridization mechanism, system active control method with reduced solar radiation and mid-temperature chemical looping cycle method. Focusing on the entire energy conversion process of “solar radiation-heat-chemical energy-power”, the relationship of maximum available work among concentrated solar energy, fossil fuel chemical energy, Gibbs free energy and thermal cycle was built, the maximum available work variation rules of concentrated solar energy was revealed, and the energy-level improvement mechanism of mid-temperature solar energy and the net solar-to-electricity efficiency enhancement mechanism by solar thermochemical hybridization were explored. Studying on the effects of chemical reaction parameters and oxygen carrier materials on the chemical looping cycle irreversibilities, the oxygen carrier system with low activation energy barrier was developed. The irreversibility distribution under the cooperative control of system parameters was revealed, and the solar energy cascade utilization by the method of solar thermochemical hybridization coupling with solar thermal hybridization under low solar radiation was proposed. The solar-to-electricity efficiency is expected to improve by 15-20% comparing with the conventional solar-only thermal power system. The research outcomes shall form new methodologies for high-efficiency solar thermochemical cycling, address the low-efficiency problem of solar thermal power system.

本项目突破高温高效发电必然要求高倍聚光、高温集热的常规思路，以太阳能热化学互补发电系统为研究对象，在聚光太阳能、化学反应、热力循环的交叉层面，探索核心科学问题：中温太阳能热化学互补机理、变辐照主动调控方法、中温化学链反应循环方法；针对光-热-化学能-功的能量转化过程，建立聚光太阳能、燃料化学能、燃料转化Gibbs自由能、热力循环热能最大作功能力的相互作用关系，揭示太阳能最大作功能力的演变规律，探索中温太阳能品位提升机理和太阳能净热发电效率增效机制；研究反应参数、氧载体材料对化学链循环不可逆性的影响规律，实验研发中温低活化能垒的氧载体体系；揭示系统各参数协同控制的不可逆性分布规律，提出变辐照工况太阳能热化学互补与热互补耦合的太阳能综合梯级利用新方法；预计太阳能净发电效率可比现有单纯太阳能热发电技术高15-20个百分点。研究成果将形成高效太阳能热化学发电新方法，破解太阳能热发电效率低下的难题。

本项目以太阳能中温热化学互补发电系统为研究对象，开展了太阳能热化学互补发电过程中的理论和实验研究。建立了多能源能势、反应品位之间的基本关系，阐述了多能源热化学互补品位耦合机理，揭示了太阳能净发电效率的变化规律。中低温热化学互补反应具有品位耦合效果较好和互补过程不可逆性小的优点，为中低聚光比太阳能驱动甲烷通过化学链燃烧的热化学互补提供了理论基础。研制了掺杂铜的镧镍基钙钛矿氧载体材料，具有良好的循环再生性和稳定性，与甲烷反应热力学和动力学性能良好。提出了热化学互补化学链循环新方法，将太阳能甲烷重整与钙钛矿化学链循环相耦合的新思路，在450°C下，甲烷转化率达到99%以上。优化了热化学互补和热互补耦合的变辐照主动调控方法。改进了中温太阳能与甲烷热化学互补与源头蓄能关键技术，建立了太阳能与化石能源互补的源头蓄能发电系统模型。模型计算结果表明太阳能净发电效率比现有单纯太阳能热发电技术高约18个百分点，为破解同类太阳能热化学净发电效率低的难题提供了有力支撑。