碘硫循环是很有前景的核能制氢技术，可实现高效、清洁、大规模制氢，并可有效拓展核能非电应用领域。Bunsen反应及产物分相是循环稳定运行的核心环节，目前仍存在相态调控困难、双水相组成难以保持稳定等难题。本课题拟从相平衡角度研究并阐明H2SO4/HI/I2/H2O四组分体系在多种条件下的相平衡规律，用四面体相图表达相态并建立相态预测方法；在双水相平衡条件下，综合实验结果和混合电解质溶液活度计算理论，发展可靠的组成计算模型；用微量热法研究硫酸和氢碘酸水合热，获得非计量比条件下Bunsen反应热力学数据；研究模拟循环条件下Bunsen反应工艺，并将产物相态和组成实验结果与模型预测结果对比，优化工艺并完善模型。研究结果可提供相关体系热力学和相平衡的关键基础数据，阐明非稳态输入条件下Bunsen反应条件优化、产物相态调控、扰动与干预的科学原理与与机制，为碘硫循环连续稳定运行、提高制氢效率提供理论依据。

Iodine sulfur (IS) process, which can achieve the efficient, CO2 free and massive hydrogen production, is a prospective nuclear hydrogen production approach. The Bunsen reaction and spontaneous separation of its products are crucial issues for the continuous and stable operation of IS cycle, however, the adjustment and control of the phase states, as well as maintaining the stable compositions of the products, are still remain difficult. In this proposal, some novel views and approaches are proposed and to be conducted. Firstly, the phase equilibrium of the H2SO4/HI/I2/H2O quaternary system is to be extensively studied, a tetrahedron diagram is proposed to express the phase states, and the prediction model for phase states will be built. Secondly, a reliable calculation method and model, which are for the calculation of the compositions of the two liquid-liquid equilibrated solutions, are to be developed based on the experiments results and the mixed electrolyte activity calculation theory. Thirdly, the hydration heat of HI acid and H2SO4 under various conditions will be measured by micro calorimetry, and the thermodynamics data of Bunsen reaction under non-stoichiometric conditions will be obtained. Fourthly, the reaction process will be studied under the simulated cycling conditions of IS process, the results on phase states and compositions will be obtained and compared with those obtained by the built models, so that the parameters could be optimized, and the models could be improved based on the results. Overall, the results of this project will supplement crucial data of the thermodynamics and phase equilibrium of H2SO4/HI/I2/H2O quaternary system, clarify the scientific principle and mechanism for the optimization of Bunsen reaction parameters, adjustment, control, disturbance and intervention of phase states, and provide theoretic basis for the stable operation and efficiency improvement of IS process.