摘要
基于Ca(OH)_(2)/CaO的热化学储能体系在实验中均表现出孔隙结构的显著变化,而该现象在已有的大多数数值模拟研究中并未被考虑。本文针对该现象建立了变孔隙率反应动力学模型及非稳态“流动–传热–化学反应”耦合模型,并基于此对直接、间接传热式固定床反应器中Ca(OH)_(2)/CaO的定/变孔隙率脱水反应过程特征参数(反应渗透率、压力、温度、反应速率及转化率等)变化进行了对比模拟研究。结果表明:定孔隙率模型与变孔隙率模型之间有明显的差异,且变孔隙率模型更能体现实际反应过程的特征。以初始孔隙率为0.8的工况为例,定孔隙率假设在直接传热式反应器中的转化速率比变孔隙率模型快19.8%,而在间接传热式反应器中转化速率比变孔隙率慢6.1%。说明以往研究中使用的定孔隙率假设高估了直接传热式反应器的性能,而低估了间接传热式反应器的性能。
The thermochemical energy storage systems based on Ca(OH)_(2)/CaO system show significant changes in the pore structure in experiments, which has not been considered in most of the existing numerical simulation studies. In this paper, a reaction kinetic model with variable porosity and an unsteady coupling model of ”flow-heat-transfer-chemical reaction” are established for this phenomenon. Based on these results, the characteristics of Ca(OH)_(2)/CaO dehydration reaction process(permeability, pressure, temperature, reaction rate and conversion, etc.) in direct and indirect heat transfer fixed-bed reactors were compared and simulated. The results show that there are obvious differences between the constant porosity model and the variable porosity model, and the variable porosity model can better reflect the characteristics of the actual reaction process. Taking the initial porosity of 0.8 as an example, the conversion rate of the constant porosity model in the direct heat transfer reactor is nearly 19.8% faster than that of the variable porosity model, while the conversion rate of the indirect heat transfer reactor is about 6.1% slower than that of the variable porosity model. The results show that the constant porosity assumption used in previous studies overestimates the performance of direct heat transfer reactors and underestimates the performance of indirect heat transfer reactors.
作者
徐其利
孙杰
魏进家
XU Qili;SUN Jie;WEI Jinjia(School of Chemical Engineering and Technology,Xi'an Jiaotong University,Xi'an 100190,China)
出处
《工程热物理学报》
EI
CAS
CSCD
北大核心
2023年第2期289-296,共8页
Journal of Engineering Thermophysics
基金
国家重点研发计划项目(No.2021YFF0500404)。
