An optimization model for a multistage latent heat storage (LHS) unit with unsteady heat transfer fluid (HTF) inlet temperature was proposed. Thermodynamic analysis and optimization were performed based on the entransy theory. The expressions of the optimum phase change material (PCM) melting temperatures (T_m,opt) were derived. The effects of geometric parameters and unsteady HTF inlet temperature on the optimum phase change temperatures were investigated. The results indicate that with the increase of stage number (n), T_m1,opt increases and T_mn,opt decreases, which is beneficial to extend the selection range of PCM. For fixed entransy dissipation condition, increasing n will not change the fluctuation of the HTF outlet temperature; however a nearly uniform HTF outlet temperature can be obtained by increasing unit length (L). The unsteady HTF inlet temperature has great effects on the optimum phase change temperature. For a 3-stage LHS unit, the optimum phase change temperature of each stage increases by 14.9 K, 26.4 K and 38.0 K respectively with respect to the values obtained by steady method, which causes the heat storage capacity decreases by 6.1% and entransy dissipation decreases by 10.6%. The present work can provide guidance for the design of the multistage LHS unit with unsteady HTF inlet temperature.

提出了具有非稳态传热流体（HTF）入口温度的多级潜热存储（LHS）单元的优化模型。基于熵理论进行热力学分析和优化。推导了最佳相变材料（PCM）熔化温度（T _m，opt）的表达式。研究了几何参数和非稳态HTF入口温度对最佳相变温度的影响。结果表明，随着级数（n）的增加，T _m1，opt增大，T _mn，opt减小，这有利于扩展PCM的选择范围。对于固定的传输耗散条件，增加n不会改变HTF出口温度的波动；但是，通过增加单位长度（L）可以获得接近均匀的HTF出口温度。HTF入口温度不稳定会对最佳相变温度产生很大影响。对于三段式LHS装置，每段的最佳相变温度相对于通过稳定方法获得的值分别增加14.9 K，26.4 K和38.0 K，这将导致储热能力下降6.1％并散失热量下降了10.6％。本工作可为HTF入口温度不稳定的多级LHS单元的设计提供指导。