共查询到18条相似文献,搜索用时 531 毫秒
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本文基于石蜡和泡沫金属铜制备了复合相变蓄热材料,设计并搭建了可视化蓄热实验装置,分析了泡沫金属铜填充率对石蜡蓄热过程的强化传热机理。实验结果表明:当泡沫金属铜的填充率从0增至2.13%时,复合相变蓄热材料的融化时间从901 s缩短至791 s,缩短了12.21%;当泡沫金属铜的填充率为2.13%时,石蜡内部的温度梯度最小,为22.52 K。此外,随着泡沫金属铜填充率的增加,复合相变蓄热材料的蓄热量从15 932 J减小至13 296 J,减少了16.55%,蓄热速率先减小后增大,分别为18.41、18.33、18.64、19.13 J/s,当泡沫金属铜的填充率为0.99%时,蓄热装置中石蜡的蓄热量为14 539 J,蓄热速率为18.52 J/s,蓄热装置的蓄热性能较好。 相似文献
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《功能材料》2016,(11)
以石蜡类正二十烷相变材料为填充材料,泡沫碳为基体材料,制备了石蜡/泡沫碳相变复合材料。采用差示扫描量热法(DSC)分析了正二十烷相变材料的热物性,通过扫描电子显微镜(SEM)分别获得了泡沫碳和正二十烷/泡沫碳相变复合材料的表面形态图像。搭建了相变蓄热装置实验台,对3种不同材料的相变蓄热装置进行蓄放热对比实验,记录并分析了相变蓄热装置温度测试数据。与正二十烷的结果对比,泡沫材料的填充大幅提高相变材料的传热性能。在蓄热过程中,泡沫复合相变材料的升温速率明显降低;在放热过程中,正二十烷/泡沫碳相变复合材料温度恢复至室温的时间比纯二十烷恢复至室温的时间减少约30%。 相似文献
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采用有限元方法模拟圆柱体潜热蓄热系统中的相变蓄热过程。该模型为:以圆柱体封装装置存储相变物质石蜡,圆柱体中间插入一根热水铜管给相变物质供热,不同数量的铜肋片或者不同质量分数的压缩膨胀石墨用于提高相变传热速率。其中铜肋片沿圆柱体径向方向插入圆柱体内;熔融石蜡经过真空浸渗到压缩膨胀石墨内形成压缩膨胀石墨/石蜡复合材料,然后将复合材料填充到圆柱体内。该模型包括四个物理过程:热传导、流体流动、相变传热和对流传热。模拟结果表明,不同数量的铜肋片以及不同质量分数的压缩膨胀石墨对相变储热速率均有明显提高。添加压缩膨胀石墨比添加铜肋片更经济,传热更均匀。 相似文献
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This study analyzes the reproducibility of solidification and melting tests in a tank containing 181 kg of paraffin for cold storage at around 8 °C. Firstly, an experimental campaign of 10 identical tests was carried out. The performance is practically the same in terms of PCM temperatures and thermal power, with a maximum deviation of 2% in the capacity of all tests. In a second campaign, the impact of the initial conditions was studied. The results indicate that fixing a same mean PCM temperature at the beginning of the tests is insufficient to ensure an accurate reproducibility. Depending on the heat transfer rate during the preparation tests, the capacity differed in up to 33%. In tanks with such quantities of PCM, fixing a uniform initial PCM temperature is hardly possible, thus it is important to prepare the tank with same operation conditions. 相似文献
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相变装置中填充泡沫金属的传热强化分析 总被引:9,自引:1,他引:8
通过对泡沫金属结构的分析,将泡沫金属结构简化为二维的循环扩展六边形网格形式,且传热单元被分为九个导热层。在此基础上以热阻分析推导出了在泡沫金属作为填充材料时其整体有效导热系数Koff与泡沫金属空隙率ε之间的数学关系式。分别以泡沫铜、泡沫铝填充石蜡为例与用铜、铝翅片并联和串联两种方式填充石蜡时的有效导热系数进行了计算对比,从计算结果可以明显看出采用泡沫金属作为填充材料,其整体效果要优于翅片,可显著改善相变储能装置的传热性能及储能效率。 相似文献
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石蜡相变材料强化传热技术进展 总被引:1,自引:0,他引:1
介绍了相变材料(PCM)的分类及应用,石蜡类有机相变材料具有较高的相变潜热,无过冷及析出现象,性能稳定、无毒、价格便宜,但也存在导热系数小、密度小的缺点;阐述了国内外为强化石蜡相变材料传热对其所作的大量研究;示出了常用相变传热的传热模型和相变传热问题的求解方法。 相似文献
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Yu ZhuHaitao Hu Guoliang Ding Hao PengXiangchao Huang Dawei ZhuangJun Yu 《International Journal of Refrigeration》2011,34(2):509-517
Nucleate pool boiling heat transfer characteristics of refrigerant/oil mixture on metal foam covers were experimentally investigated. The refrigerant is R113, and the oil is VG68. The copper foams, having ppi (pores per inch) of 10 and 20, porosity from 90% to 98%, and thickness of 5 mm, are selected in this study. Experimental conditions include a saturation pressure of 101 kPa, oil concentrations from 0 to 5%, and heat fluxes from 0 to 80 kW m−2. The experimental results indicate that the nucleate pool boiling heat transfer coefficient on copper foam covers is larger than that on flat heated surface by a maximum of 160% under the present experimental conditions; the presence of oil deteriorates the nucleate pool boiling heat transfer on copper foam covers by a maximum of 15% under the present experimental conditions, and the deterioration of oil on nucleate pool boiling heat transfer on copper foam covers is lower than that on a flat heated surface. A correlation for predicting the nucleate pool boiling heat transfer coefficient of refrigerant/oil mixture on copper foam cover is developed, and it agrees with 95% of the experimental data within a deviation of ±20%. 相似文献
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Guoqiang Qi Jie Yang Ruiying Bao Dongyun Xia Min Cao Wei Yang Mingbo Yang Dacheng Wei 《Nano Research》2017,10(3):802-813
Recently,graphene foam (GF) with a three-dimensional (3D) interconnected network produced by template-directed chemical vapor deposition (CVD) has been used to prepare composite phase-change materials (PCMs) with enhanced thermal conductivity.However,the pore size of GF is as large as hundreds of micrometers,resulting in a remarkable thermal resistance for heat transfer from the PCM inside the large pores to the GF strut walls.In this study,a novel 3D hierarchical GF (HGF) is obtained by filling the pores of GF with hollow graphene networks.The HGF is then used to prepare a paraffin wax (PW)-based composite PCM.The thermal conductivity of the PW/HGF composite PCM is 87% and 744% higher than that of the PW/GF composite PCM and pure PW,respectively.The PW/HGF composite PCM also exhibits better shape stability than the PW/GF composite PCM,negligible change in the phase-change temperature,a high thermal energy storage density that is 95% of pure PW,good thermal reliability,and chemical stability with cycling for 100 times.More importantly,PW/HGF composite PCM allows light-driven thermal energy storage with a high light-to-thermal energy conversion and storage efficiency,indicating its great potential for applications in solar-energy utilization and storage. 相似文献
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导热系数低是影响相变储热材料应用的主要难题之一,而泡沫金属具有高热导率、高孔隙率以及高比表面积等特性,在相变材料中添加泡沫金属可实现强化传热。该文基于泡沫金属基3D微观结构W-P模型,重点分析了泡沫金属基复合相变材料有效导热系数与泡沫金属孔隙率以及孔径的关系,采用数值模拟方法利用该模型预测并验证了泡沫铝6101添加空气与水的有效导热系数,研究结果表明该模型能够精确预测泡沫金属材料有效导热系数,在此基础上预测了石蜡中添加泡沫铜的有效导热系数,结果表明,泡沫金属可以显著提高相变材料的导热系数,当泡沫铜的孔隙率为97.57%时,复合相变材料的导热系数与纯石蜡相比提高了13倍。研究结果对于相变储热材料的热物性强化研究具有一定参考价值。 相似文献