摘要
针对管壳式相变储热单元换热效率低的问题,设计一种带有径向矩形翅片的复合盐管壳式相变储热单元,进行数值模拟并与实验研究对比验证,然后选择适当的性能指标分析模拟结果.采用ANSYS FLUENT进行三维瞬态仿真,改变换热流体入口温度及储热单元翅片间距进行储热过程的数值计算,对相变材料温度变化、传热过程及熔化情况进行对比分析.结果表明:提高换热流体温度和缩小翅片间距是有效强化换热的手段.在本工作中,换热流体与相变材料复合盐CH3COONa·3H2O-KCl相变温差每增加5℃,相变材料熔化速率分别提升 54.98%、34.67%、23.92%、18.13%、14.45%,潜热储热速率分别提升 61.56%、45.79%、35.15%、27.04%、22.31%,速率提升效果均逐渐减弱.翅片间距每缩短10 mm,相变材料熔化速率分别提升32.37%、41.26%、38.66%,储热量随之减少6.40%、11.95%、6.55%,储能密度降低0.53%、10.97%、1.57%,实际应用中需综合换热能力、成本等方面问题选择合适的翅片间距.本工作可为实际工程中储热单元的设计优化提供理论支持.
Abstract
To address the low heat transfer efficiency in shell-and-tube phase change thermal storage units,a new design featuring radial rectangular fins within a composite salt shell-and-tube structure was proposed.Numerical simulations were carried out and verified against experimental data,followed by an analysis using appropriate performance metrics.Three-dimensional transient simulations were conducted using ANSYS FLUENT,where the inlet temperature of the heat transfer fluid and the spacing between fins were varied to model the thermal storage process.The study focused on comparing and analyzing temperature variations of the phase change material,heat transfer processes,and melting conditions.The results indicate that increasing the temperature of the heat transfer fluid and reducing the spacing between the fins are effective methods for enhancing heat transfer.Specifically,for every 5℃ increase in the temperature difference between the heat transfer fluid(water)and the phase change material composite salt(CH3COONa·3H2O-KCl),the melting rates of the phase change material increased by 54.98%,34.67%,23.92%,18.13%,and 14.45%,respectively,while the latent heat storage rates increased by 61.56%,45.79%,35.15%,27.04%,and 22.31%,respectively,with diminishing returns as the temperature difference grew.Additionally,reducing the fin spacing by 10 mm led to increases in the melting rates of the phase change material by 32.37%,41.26%,and 38.66%,though it also leads to corresponding reductions in thermal storage capacity of 6.40%,11.95%,and 6.55%,and in energy storage density of 0.53%,10.97%,and 1.57%,respectively.In practical applications,the fin spacing should be optimized by considering both heat transfer efficiency and cost.The research provides theoretical support for the design and optimization of thermal storage units in engineering applications.
基金项目
国家重点研发计划项目(2021YFB1507200)
国家重点研发计划项目(2021YFB1507203)
国家科技期刊平台
NSTL
万方数据