基于热化学反应的硅胶非等温动力学计算及储热性能分析  

Non-isothermal kinetics calculation and heat storage performance analysis of silica gel based on thermochemical reaction

作　　者：杨娜 王成成 杨慧 胡志昊 童莉葛 李仲博[2] 王立 丁玉龙[3] 李娜 YANG Na;WANG Chengcheng;YANG Hui;HU Zhihao;TONG Lige;LI Zhongbo;WANG Li;DING Yulong;LI Na(School of Energy and Environmental Engineering,University of Science and Technology Beijing,Beijing 100083,China;Beijing District Heating Group,Beijing 100028,China;School of Chemical Engineering,University of Birmingham,Birmingham B152TT,UK;State Grid Integrated Energy Service Group Co.,Ltd.,Beijing 100052,China)

机构地区：[1]北京科技大学能源与环境工程学院,北京100083 [2]北京市热力集团有限责任公司,北京100028 [3]英国伯明翰大学化工学院,英国伯明翰B152TT [4]国网综合能源服务集团有限公司,北京100052

出　　处：《储能科学与技术》2022年第5期1331-1338,共8页Energy Storage Science and Technology

摘　　要：热化学储热具有储能密度大、循环性能好、储存时间长且热损失小等优点,在提高能源利用率、减少碳排放方面具有广阔的前景。在大规模系统流程应用前,通过实验检测、动力学计算、数值模拟仿真等手段对储热材料进行适用性判断具有重要意义。本文以硅胶为例,使用核磁共振仪检测其储热前后内部水结合形式及其含量的变化,进而计算确定了硅胶储热过程中的热化学反应方程式。根据热重分析仪(TGA)实验数据,对硅胶热分解反应进行了非等温动力学计算,得到其反应活化能为66.75 kJ/mol,且随着反应进程的推进,硅胶脱水反应整体呈活化能减小态势,其最概然机理函数为三维扩散模型,水蒸气在气固反应界面的三维扩散速率是影响总反应速率的关键。由差示扫描量热仪(DSC)实验得出,硅胶在100℃左右吸热速率达到顶峰,约为0.87 kW/kg,储热密度为1030.89 k J/kg。使用计算所得动力学参数在Fluent软件中对反应器内储热过程进行了模拟,采用Pearson相关系数作为实验与数值模拟结果的相关性评价指标,结果表明数值模拟预测值与实验值具有良好的一致性。Thermochemical heat storage has the advantages of high energy storage density,good cycling performance,long storage time and small heat loss,and has a broad prospect in improving energy efficiency and reducing carbon emissions.Before the application of largescale system process,it is of great significance to judge the applicability of heat storage materials by means of experimental detection,dynamic calculation and numerical simulation.In this paper,taking silica gel as an example,nuclear magnetic resonance instrument was used to detect the change of the internal water binding form and its content before and after heat storage,and then the thermochemical reaction equation in the process of silica gel heat storage was calculated and determined.According to the experimental data of thermogravimetric analyzer(TGA),the non-isothermal kinetic calculation of the thermal decomposition reaction of silica gel was carried out,and the activation energy of the reaction was obtained to be66.75 kJ·mol-1.With the advance of the reaction process,the activation energy of silica gel dehydration reaction decreased as a whole,and the most probable mechanism function was the three-dimensional diffusion model.The three-dimensional diffusion rate of water vapor at the gas-solid interface is a key step affecting the total reaction rate.According to differential scanning calorimeter(DSC)experiment,the heat absorption rate of silica gel reaches its peak at about 100℃,about 0.87 kW·kg-1,and the heat storage density is 1030.89 kJ·kg-1.The calculated kinetic parameters were used to simulate the heat storage process in the reactor in Fluent,and Pearson correlation coefficient was used as the evaluation index of the correlation between the experimental and numerical simulation results.The results show that the numerical simulation predicted value is in good agreement with the experimental value.

关 键 词：热化学储热 非等温动力学 核磁共振检测 储热密度 

分 类 号：TK02[动力工程及工程热物理]