碱土金属卤化物吸附过程热力学亚稳态机制、动态特性优化及衰减抑制研究

To solve the problems, system performance fluctuating and low efficiency, which are caused by the unstable dynamic adsorption character and unclear-cut mechanisms of pseudo-equilibrium area and performance attenuation during alkaline earth metal halide (AEMH) adsorption process, the thermodynamic equilibrium equations of pseudo-equilibrium area are built with considering the metastable character of AEMH and its clathrate, and then the discipline of pseudo equilibrium area's occurrence, development and evolution process are studied, the measures to control pseudo-equilibrium area are acquired. Secondly, effects of operation conditions on dynamic adsorption characteristic are studied, and the influencing rules of pseudo-equilibrium area on heat conduction, mass transfer and reaction kinetics are revealed, furthermore dynamic model of heat conduction and mass transfer is constructed, at the same time, the reaction kinetic model is developed by introducing a microstructure factor of adsorbent. Through verification and correction of the model with experiments of adsorption bed, a more practical mathematic model is eventually developed, and the theoretic foundation that can be used for adsorption bed design optimization and system performance prediction & improvement is provided. At last, the metastable state of AEMH is quantified by free energy, and the relationship between its performance attenuation and molecular degree of order is defined. The inner mechanisms of metastable state and attenuation performance are also revealed. After that, the mathematical relationship between preparation factors and metastable state is built, and then the mechanism of adsorbent attenuation and the theory of composite adsorbent inhibiting attenuation are acquired. All in all, important theory and technical support can be established for developing high performance AEMH composite adsorbents and improving system operation performance.

针对碱土金属卤化物(AEMH)吸附过程中伪平衡区、性能衰减机制不明及动态吸附特性不稳定，致使系统性能波动、效率低的难题。本项目拟从AEMH及其络合物的亚稳态特性切入，构建伪平衡区热力学平衡态方程，研究伪平衡区发生、发展及其演变的规律，获得有效调控伪平衡区的措施；研究运行工况对动态吸附特性的影响，揭示伪平衡区对导热、传质及反应动力学的影响规律，构建导热及传质动态模型，引入吸附剂微观形貌因子，发展反应动力学模型，通过吸附床实验对模型验证和修正，形成符合实际的动态特性数学模型，为吸附床设计优化和系统性能预测及改善提供理论支撑；以自由能量化表现AEMH亚稳态的状态，明确其性能衰减与分子有序度的关系，揭示亚稳态与性能衰减的内在机制，以此建立制备因素对亚稳态影响的数学表达，获得吸附剂衰减机制及复合吸附剂抑制衰减原理，为高性能AEMH复合吸附剂开发及系统运行性能改善提供重要的理论和技术支撑。

针对碱土金属卤化物(AEMH)吸附过程中伪平衡区产生机制不明确，衰减原因不清，动态吸附特性不稳，引入亚稳态机制，基于严格的数学推导，发展完善了平衡态方程，解释了亚稳态及传热传质导致的伪平衡区现象，拟合了常用工况的平衡态方程；基于容积法设计了具备测试吸附剂动力学、平衡态及长期循环性能的综合测试平台，构建了单位质量制冷量快速量化表征方法，实现了吸附剂综合性能的快速量化表征，总体测试精度小于2.3%；研发微量样品渗透率测试平台，可用于不同吸附量的渗透率测试，采用实际气体模型拟合渗透率，提高了渗透率测试精度，小于4%；研发了一类廉价高精度的探头，实现了高压腔体内吸附材料导热系数随着吸附量变化的动态测试，测试精度小于2%。针对微量吸附剂样品综合性能快速定量表征方法缺乏问题，基于理想吸附循环过程，构建了定容法吸附剂单位质量功率密度(SCPv)快速表征方法，提出吸附剂长期循环性能测试方案，在吸附剂实际测试过程，SCPv值能够良好的表现吸附剂当前吸附总体性能，结合长期循环性能测试结果，可以准确全面的反应吸附剂样品的真实性能，形成了系统的吸附剂性能表征方法；针对膨胀石墨基质比表面积偏低，高度分散时AEMH负载量小的问题，提出了一种提出可溶性糖为炭质前驱物的复合吸附剂制备新方法，获得了一种石墨-碳膜-盐复合吸附剂，性能提升21.8%以上，同时抗衰减能力有效增强；新型复合吸附剂传热传质能力基本与石墨氯化钙样品相近，实现了吸附剂传热、传质、动力学和抗衰减能力的协同优化。考虑吸附剂实际结构，基于收缩未反应核模型引入形状因子，完善了吸附剂动力学模型，实际预测误差小于5%。