Cold storage condensation heat recovery system with a novel composite phase change material
Cold storage condensation heat recovery system with a novel composite phase change material
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DOI：
10.1016/j.apenergy.2016.05.001
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发表时间：
2016-08
期刊：
影响因子：
11.2
通讯作者：
Mingzhu Xia;Yanping Yuan;Xudong Zhao;Xiaoling Cao;Zhonghua Tang
中科院分区：
文献类型：
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作者：
Mingzhu Xia;Yanping Yuan;Xudong Zhao;Xiaoling Cao;Zhonghua Tang
利用冷藏制冷系统的冷凝热量为生活热水制备和工业热水供应提供热量，促进了节能。然而，利用相变材料(PCM)进行冷藏冷凝热回收的研究很少。在本研究中，设计并分析了一种使用相变材料的冷库冷凝热回收系统。根据能量梯级回收的原理，可以有效地切换不同的运行方式来回收冷凝热。此外，还开发了一种新型的适用于冷藏冷凝热回收的相变复合材料，该材料具有较大的潜热、较高的导热系数和合适的相变温度(即80℃)。以巴西棕榈蜡(CW)为相变材料，以膨胀石墨(EG)为添加剂，制得了最佳质量比为CW：Eg=10：1的复合材料。用扫描电子显微镜(SEM)、热常数分析仪(热盘)、差示扫描量热仪(DSC)和傅立叶红外光谱仪(FT-IR)研究了复合材料的热性能、物理性能和内部结构。此外，还进行了熔化和凝固过程以及加速热循环的实验。结果表明，当最佳质量比为10：1时，CW/EG复合材料的熔融和凝固温度分别为81.98℃和80.43℃，相对应的潜热分别为150.9和142.6℃。在这两个过程中，CW被EG完全吸附后仍能保持其原有的蠕虫状结构。与纯CW相比，CW/EG复合材料的熔融时间和凝固时间分别缩短了81.7%和55.3%，导热系数提高了16.4倍。1000次加速热循环后，CW和CW/EG复合材料的吸放热相变温度分别提高了0.42%/0.42%和0.23%/0.27%，吸放热潜热分别降低了4.96%/4.78%和2.05%/3.44%。这些结果表明，CW和CW/EG复合材料都具有良好的热可靠性，而CW/EG复合材料的性能略好。实验结果表明，CW/EG复合材料具有较高的导热系数和可靠性等良好的热物性，是一种很有潜力的冷藏制冷系统冷凝热回收材料。
Using condensation heat from cold storage refrigeration systems to provide heat for domestic hot water preparation and industrial hot water supply promotes energy conservation. However, few studies have investigated cold storage condensation heat recovery using phase change materials (PCMs). In this study, a cold storage condensation heat recovery system that uses PCMs has been designed and analysed. According to the principle of energy cascade recycling, different operation modes could be effectively switched to recycle condensation heat. Furthermore, a novel and suitable phase change composite material is developed for cold storage condensation heat recovery, which has a relatively large latent heat, high thermal conductivity, and an appropriate phase change temperature (i.e. 80 °C). With carnauba wax (CW) as the PCM and expanded graphite (EG) as the additive, a composite was developed with an optimal mass ratio of CW:EG = 10:1. The thermal and physical properties and the interior structure of the composite were then investigated using a scanning electron microscope (SEM), thermal constants analyser (Hot Disk), differential scanning calorimeter (DSC), and Fourier transform infrared spectrometer (FT-IR). Furthermore, experiments on the melting and solidification processes and accelerated thermal cycling were also conducted. It was found that at the optimal mass ratio of 10:1, the temperatures of the CW/EG composite in the melting and solidification processes were 81.98 °C and 80.43 °C, respectively, while the corresponding latent heats were 150.9 J/g and 142.6 J/g, respectively. During both processes, CW could retain its original worm-like structure after being completely adsorbed by EG. Compared to only CW, the melting and solidification time of the CW/EG composite were reduced by 81.7% and 55.3%, respectively, while its thermal conductivity was 16.4 times higher. After 1000 runs of accelerated thermal cycling, the endothermic/exothermic phase change temperatures of CW and the CW/EG composite increased by only 0.42%/0.42% and 0.23%/0.27%, respectively, while their endothermic/exothermic latent heats decreased by 4.96%/4.78% and 2.05%/3.44%, respectively. These results indicate that both CW and the CW/EG composite have excellent thermal reliability, while the CW/EG composite exhibits a slightly better performance. Finally, the experiments show that the CW/EG composite has desirable thermal and physical properties such as high thermal conductivity and reliability; Hence, it has good potential as a material for facilitating condensation heat recovery from cold storage refrigeration systems.