Abstract Latent heat thermal energy storage (LHTES) using phase change material (PCM) has many application potentials, in view of the fact that it has higher thermal energy storage capacity than the sensible heat thermal energy storage such as stratified water storage (SWS). However, the stored thermal energy in an LHTES system is not all effective in discharging due to the additional heat transfer resistance between PCM and heat transfer fluid (HTF). An LHTES system could have a higher effective storage capacity than an SWS system only if it is well designed. The optimal design of an LHTES system could be realized only after the effective energy storage ratio, Est, is analyzed in the design stage. In comparison to the laborious computational analysis method, in this work, we developed an analytical technique from the effectiveness-NTU theory to calculate the required heat transfer length and predict Est of the basic unit in any tube-in-tank LHTES system. The technique was first compared with the numerical simulation method we reported earlier, and then used to find the optimal design under various constraints. It was shown that heat transfer enhancement in PCM could effectively improve the effective storage capacity of an optimal design. However, the maximum Est was limited by the thermal resistance in HTF when the enhancement in PCM was over a certain threshold. It was demonstrated that the use of HTF in a low-Re turbulent region could enhance heat transfer in HTF and achieve an Est as high as that in a laminar region while obtaining a higher discharging rate if heat transfer in PCM was well enhanced. This analysis provided quantitative guidelines on designing optimal tube-in-tank LHTES systems.

中文翻译：

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一种使用 PCM 优化设计罐中管热能存储系统的分析技术

摘要 相变材料（PCM）的潜热蓄热（LHTES）具有比分层水存储（SWS）等显热蓄热更高的蓄热能力，具有许多应用潜力。然而，由于 PCM 和传热流体 (HTF) 之间的额外传热阻力，LHTES 系统中存储的热能在排放方面并不完全有效。只有设计得当，LHTES 系统才能比 SWS 系统具有更高的有效存储容量。只有在设计阶段分析了有效储能比 Est 后，才能实现 LHTES 系统的优化设计。与费力的计算分析方法相比，在这项工作中，我们根据有效性-NTU 理论开发了一种分析技术，用于计算所需的传热长度并预测任何罐中管 LHTES 系统中基本单元的 Est。该技术首先与我们之前报道的数值模拟方法进行比较，然后用于寻找各种约束条件下的最佳设计。结果表明，PCM 中的传热增强可以有效提高优化设计的有效存储容量。然而，当 PCM 中的增强超过某个阈值时，最大 Est 受到 HTF 中热阻的限制。结果表明，在低 Re 湍流区域使用 HTF 可以增强 HTF 中的传热并实现与层流区域一样高的 Est，同时如果 PCM 中的传热得到很好的增强，则可以获得更高的放电率。