钙镁水合盐多孔复合储热材料的热质传输与水合反应耦合机理研究

As a kind of seasonal heat storage material, composite salt hydrate thermochemical heat storage material has attracted more and more attention in recent years. Because of the complicated heat and mass transfer process, which is coupled with hydration reaction at the same time, the heat storage density is unstable and the heat power is low. Therefore, in this research, the composite material composes the high heat storage property material MgCl₂+2CaCl₂ would be taken as the research object. This research will focus on the following topics: (1) The equilibrium hydration performance of the composite material will be studied experimentally, and its equilibrium hydration theoretical model will be established. (2) The reaction kinetics of the composite material will be studied by conducting experiments, and the reaction kinetics model of the composite material will be build. Then the effects of pore size distribution, pore volume and specific surface area on the hydration mechanism and reaction control mechanism of the composite material will be analyzed and clarified. (3) Composite material pellet containing multiple grains will be prepared based on the composite thermochemical material after pore properties optimization. The permeability, effective thermal conductivity and comprehensive reaction dynamic performance of composite material pellet will be studied experimentally. On the basis of the above research, a numerical model of coupled hydration reaction and heat and mass transfer will be established, and the processes of gas flow, mass transfer and energy transfer will be described. The coupling mechanism of the heat and mass transfer and hydration reaction of composite thermochemical heat storage material based on calcium magnesium salt hydrate will be revealed, and the composite thermochemical heat storage material can be optimized. Thus the research project is conducive to promoting the large-scale application of thermochemical heat storage technology.

水合盐复合材料作为一种跨季节储热材料，近年来受到越来越多的关注。然而水合反应耦合的非稳态传热传质过程极为复杂，易导致复合材料蓄热密度不稳定、放热效率较低。本项目拟以具有高蓄热性能的MgCl₂+2CaCl₂为活性组分制备成的复合多孔材料为研究对象。具体研究内容包括：（1）实验研究复合材料的平衡态水合性能，构建其平衡态水合性能理论模型；（2）实验研究复合材料的反应动力特性，搭建其反应动力学理论模型，阐明多孔材料的孔结构对复合材料的水合性能和反应动力特性的协同强化机制；（3）制备多粒子构成的复合材料成型颗粒，实验研究其传热传质特性和综合反应动力特性。在上述研究基础上，建立成型颗粒的热质传输与水合反应耦合的多物理场模型，描述成型颗粒内气体流动、物质交换和能量传输过程，揭示复合材料成型颗粒的水合反应与热质传输耦合机理，优化制备水合盐复合材料。本项目研究及其成果有利于推动热化学蓄热技术的规模化应用。

水合盐复合材料作为一种跨季节储热材料，近年来受到越来越多的关注。然而水合反应耦合的非稳态传热传质过程极为复杂，易导致复合材料蓄热密度不稳定、放热效率较低。本项目以具有高蓄热性能的MgCl₂+2CaCl₂为活性组分，以分子筛、硅藻土和活性氧化铝为基底分别制备成复合多孔材料。具体研究内容包括：（1）实验研究复合材料的平衡态水合性能，构建其平衡态水合性能理论模型；（2）实验研究复合材料的反应动力特性，搭建其反应动力学理论模型，阐明多孔材料的孔结构对复合材料的水合性能和反应动力特性的协同强化机制；（3）复合材料多粒子构成的储热系统的实验和数值模拟研究。其中以介孔硅藻土为基底的二元水合盐复合储热材料的平衡特性和吸附动力特性较好，且经过多次储热/放热循环其储热性能并未出现明显的下降。采用粒径为2mm的WSS20颗粒，填充高度为10cm的填充床反应器的储能密度达到0.985 GJ/m3，几乎是水的4倍。本项目研究及其成果有利于推动热化学蓄热技术的规模化应用。