Mahmoud Mustafa Z, Mohammed Hayder I, Mahdi Jasim M, Bokov Dmitry Olegovich, Ben Khedher Nidhal, Alshammari Naif Khalaf, Talebizadehsardari Pouyan, Yaïci Wahiba
Radiology and Medical Imaging Department, College of Applied Medical Sciences, Prince Sattam Bin Abdulaziz University, Al-Kharj 16244, Saudi Arabia.
Faculty of Health, University of Canberra, Canberra 2601, Australia.
Nanomaterials (Basel). 2021 Nov 22;11(11):3153. doi: 10.3390/nano11113153.
Due to the potential cost saving and minimal temperature stratification, the energy storage based on phase-change materials (PCMs) can be a reliable approach for decoupling energy demand from immediate supply availability. However, due to their high heat resistance, these materials necessitate the introduction of enhancing additives, such as expanded surfaces and fins, to enable their deployment in more widespread thermal and energy storage applications. This study reports on how circular fins with staggered distribution and variable orientations can be employed for addressing the low thermal response rates in a PCM (Paraffin RT-35) triple-tube heat exchanger consisting of two heat-transfer fluids flow in opposites directions through the inner and the outer tubes. Various configurations, dimensions, and orientations of the circular fins at different flow conditions of the heat-transfer fluid were numerically examined and optimized using an experimentally validated computational fluid-dynamic model. The results show that the melting rate, compared with the base case of finless, can be improved by 88% and the heat charging rate by 34%, when the fin orientation is downward-upward along the left side and the right side of the PCM shell. The results also show that there is a benefit if longer fins with smaller thicknesses are adopted in the vertical direction of the storage unit. This benefit helps natural convection to play a greater role, resulting in higher melting rates. Changing the fins' dimensions from (thickness × length) 2 × 7.071 mm to 0.55 × 25.76 mm decreases the melting time by 22% and increases the heat charging rate by 9.6%. This study has also confirmed the importance of selecting the suitable values of Reynolds numbers and the inlet temperatures of the heat-transfer fluid for optimizing the melting enhancement potential of circular fins with downward-upward fin orientations.
由于具有潜在的成本节约优势且温度分层最小，基于相变材料（PCM）的储能可成为一种可靠的方法，使能源需求与即时供应可用性脱钩。然而，由于这些材料具有高耐热性，需要引入增强添加剂，如扩展表面和翅片，以便能够将其应用于更广泛的热储能和能量存储应用中。本研究报告了如何采用交错分布和可变取向的圆形翅片来解决PCM（石蜡RT - 35）三管热交换器中热响应速率低的问题，该热交换器由两种传热流体在内管和外管中反向流动组成。使用经过实验验证的计算流体动力学模型，对传热流体在不同流动条件下圆形翅片的各种配置、尺寸和取向进行了数值研究和优化。结果表明，当翅片沿PCM壳的左侧和右侧向下 - 向上取向时，与无翅片的基础情况相比，熔化速率可提高88%，热充电速率可提高34%。结果还表明，在存储单元的垂直方向上采用厚度较小的较长翅片是有益的。这种益处有助于自然对流发挥更大作用，从而导致更高的熔化速率。将翅片尺寸从（厚度×长度）2×7.071毫米更改为0.55×25.76毫米可使熔化时间减少22%，并使热充电速率提高9.6%。本研究还证实了选择合适的雷诺数和传热流体入口温度对于优化具有向下 - 向上翅片取向的圆形翅片的熔化增强潜力的重要性。
