Experimental investigation and CFD modelling analysis of finned-tube PCM heat exchanger for space heating
Experimental investigation and CFD modelling analysis of finned-tube PCM heat exchanger for space heating
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DOI：
10.1016/j.applthermaleng.2024.122731
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发表时间：
2024-05
影响因子：
6.4
通讯作者：
X.Y. Zhang;Y.T. Ge;Burra;P.Y. Lang
中科院分区：
文献类型：
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作者：
X.Y. Zhang;Y.T. Ge;Burra;P.Y. Lang
潜热热能储存系统（LHTES）与相变材料（PCM）热交换器的集成用于空间加热具有显著的降低能耗和节省操作成本的潜力。相应地，一个专门设计的翅片管PCM热交换器制造，利用空气流作为传热流体（HTF），并将有机PCM A27管内。然后将该热交换器集成到具有受控的进入气流参数的空调单元中。通过一系列实验研究了该相变材料换热器在不同工况下充、放热过程中的传热性能。随后，对于每个过程，PCM的温度分布，热传递速率之间的HTF和PCM，以及相变时间，从实验中获得。为了进一步增强这种PCM翅片管换热器的传热和能量存储，并直观地了解能量的充放电过程，开发了经过验证的计算流体动力学（CFD）模型，以研究其在不同操作和设计条件下的性能改进，包括不同的HTF速度，不同的HTF温度，以及增强的PCM导热系数。此外，通过分析PCM熔化/固化时间的减少以及能源效率，对改进进行了量化。从实验和CFD模拟可以得出结论，较高的HTF流速可以大大缩短PCM相变的完成时间。虽然在充电过程中较高的HTF温度和在放电过程中较低的HTF温度有助于较短的相变时间，但它们都导致较低的能量效率。此外，通过改善PCM的导热性，可以分别实现熔化和固化时间的最大减少46%和35%。本研究的结果提供了有价值的操作支持和LHTES系统的优化设计标准，包括一个紧凑的PCM翅片管换热器。
The integration of a Latent Heat Thermal Energy Storage System (LHTES) with a Phase Change Material (PCM) heat exchanger for space heating has significant potential for reducing energy consumption and saving operational costs. Correspondingly, a purpose-designed finned-tube PCM heat exchanger was fabricated, utilizing airflow as the heat transfer fluid (HTF), and incorporating organic PCM A27 within tubes. This heat exchanger was then integrated into an air conditioning unit with controlled parameters of incoming airflow. A series of experiments were carried out to examine the heat transfer performance of this PCM heat exchanger throughout PCM charging and discharging processes at different operating conditions. Subsequently, for each process, PCM temperature distributions, heat transfer rates between HTF and PCM, as well as phase change times, were obtained from experiments. To further enhance the heat transfer and energy storage of this PCM finned-tube heat exchanger and visually understand the processes of energy charging and discharging, a validated computational fluid dynamics (CFD) model was developed to investigate its performance improvements at different operating and design conditions, including different HTF velocities, varied HTF temperatures, and enhanced PCM thermal conductivities. Moreover, the improvements were quantified by analysing the reductions in PCM melting/solidification times and also energy efficiencies. It can be concluded from both experiments and CFD simulations that a higher HTF flow rate can greatly reduce the completion time of PCM phase change. Although higher HTF temperature in the charging process and lower HTF temperature in the discharging process contribute to lower phase change time, they both lead to lower energy efficiencies. Moreover, it is possible to achieve maximum reductions of 46 % and 35 % in the melting and solidification times respectively by improving the thermal conductivity of PCM. The results of the present research provide valuable operation support and optimal design criteria for the LHTES system incorporating a compact PCM finned-tube heat exchanger.