非均匀热流下细小通道内相变微胶囊悬浮液传热特性

相变微胶囊悬浮液(MEPCMS)作为一种新型功能性热流体,在热管理、储能等诸多领域极具发展潜力。本文采用离散相模型(DPM)研究非均匀热流下细小水平矩形通道内MEPCMS的传热特性。结果表明：悬浮液中颗粒相变能够强化传热,在热流密度分布为9-5-5 W/cm²、进口流速为0.40 m/s、质量分数为10%时,悬浮液最高能够使壁面和流体温升分别降低8.79%和15.14%。热泳作用使颗粒在流动过程中会向低温区域迁移。与均匀热流条件相比,局部热流的分布会影响该区域及后边区域的传热特性。随着进口流速和质量分数提高,流体对壁面的冷却效果增强,同时进出口压降增加。     

相变微胶囊悬浮液的对流换热特性研究进展

相变微胶囊悬浮液是既具有流动性又兼具蓄热能力的功能性流体。相变微胶囊悬浮液在工作过程中涉及复杂的流体流动与传热以及储热过程,近年来成为国内外学者研究的热点。对相变微胶囊悬浮液在圆管、小(微)通道内的对流换热特性进行了综述,重点阐述了国内外学者对于相变微胶囊悬浮液是否能强化对流换热存在的分歧,并提出了自己的分析与看法。分析了圆管与小(微)通道对流换热机理的区别,最后概述了强化相变微胶囊悬浮液对流换热的方法。     

相变微胶囊悬浮液的研究进展

相变微胶囊悬浮液是集储热与强化传热功能于一体的新型工质,在建筑与空调节能、太阳能利用以及航空等领域有广阔的应用前景。对相变微胶囊的制备方法、相变微胶囊乳化剂、相变微胶囊悬浮液稳定性以及流变特性的研究进展进行了综述。总结了相变微胶囊悬浮液的应用研究进展,通过分析相变微胶囊悬浮液的应用实例,提出了今后的研究方向。     

微胶囊相变材料研究进展

首先介绍了微胶囊相变材料及其组成,并就微胶囊相变材料的制备方法、性能改进、性能表征以及在能量利用和热交换领域、温度控制领域和军事领域上的应用进行了综述.     

微胶囊相变乳状液在液冷服中的应用前景

介绍了一种能替代传统蓄冷介质的潜热型功能性热流体——微胶囊相变乳状液，它具有蓄冷密度大、传热性强、无过冷现象、价格低廉等优点。在传热量一定的条件下，微胶囊相变乳状液作为传热介质比水所需流量少，流动时摩擦阻力小，若用它作液冷服的冷却液可以大大减小换热管路的尺寸，降低循环泵的功耗。更重要的是，材料在发生相变前后其自身温度基本保持不变，解决了目前大多数液冷服穿着不舒适的问题。     

相变材料微胶囊研究进展

相变材料微胶囊有许多优点,如增加了热传导的面积,降低了相变材料与外界环境的反应活性并在相变发生时可以控制蓄能材料体积的变化.介绍了可作为芯材的相变材料及其主要性质,重点总结了2002年以来相变材料微胶囊的制备方法、表征与材料特点,同时讨论了国内外相变材料微胶囊在建筑节能、纺织及其他领域中的应用现状、存在的问题以及发展前景.     

乙烯基微胶囊相变材料的研究进展

综述了微胶囊相变材料及其特性,介绍了几种常用制备方法和其目前的应用领域,并重点总结归纳了乙烯基系微胶囊相变材料的研究进展,同时指出了目前存在的问题及今后的发展趋势。     

石蜡相变微胶囊及石蜡相变复合材料研究进展

介绍了石蜡相变微胶囊及石蜡相变复合材料的性能特点,阐述了原位聚合、界面聚合等主要的石蜡相变微胶囊制备方法,综述了石蜡相变微胶囊及石蜡相变复合材料在各领域内,特别是相关军事领域中的应用。     

石蜡相变微胶囊的热学性能与红外隐身性能

本研究以石蜡（PW）为芯材、三聚氰胺脲醛树脂（MUF）为壁材,采用原位聚合法制备石蜡相变微胶囊（PM）。通过ESEM、FTIR、DSC、红外热成像仪、热循环实验和破碎率测试与分析微胶囊的微观形貌、化学结构、储热性能、红外隐身性能和热稳定性。结果表明,PM1（芯壁比3∶2）和PM2（芯壁比2∶1）具有良好的储热性能,包封率分别为74.82%和75.12%,相变潜热分别为140.54 J/g和141.10 J/g。PM2具有良好的热稳定性,质量损失率为8.8%,破碎率为2.5%。掺PM2的环氧树脂具有良好的红外隐身性能,在80℃水浴加热12 min,PMER-40%(m微胶囊∶m环氧树脂=4∶6)的表面温度比环氧树脂降低了12.9℃。     

微胶囊相变材料及其应用

微胶囊相变材料是将微胶囊技术应用于相变材料而形成的新型复合相变材料。文中介绍了微胶囊相变材料及其特性,并就微胶囊相变材料的结构组成、制备方法和应用领域分别进行了综述。     

Design of microencapsulated phase change material by one-step swelling polymerization in Pickering emulsion

Microencapsulated phase change materials (MePCMs) based on swelling polymerization in Pickering emulsion were demonstrated. Monodisperse poly(glycidyl methacrylate-co-2-hydroxyethyl methacrylate) P(GMA-co-HEMA) particles were prepared by dispersion polymerization. The introduction of hydrophilic monomer HEMA endowed the obtained particles with suitable surface hydrophilicity for stabilizing Pickering emulsion. MePCMs with PGMA–polystyrene interpenetrating composite shell were formed when non-crosslinked particles were employed as stabilizer, while MePCMs with particles-embedded shell were prepared with crosslinked particles as Pickering stabilizer. Phase change property, thermal stability and thermal reliability of two kinds of MePCMs were investigated by TGA, FT-IR, DSC and cycling test. The temperature of 10% weight loss of MePCMs with interpenetrating shell was 11 °C higher than that of MePCMs with particles-embedded shell. After cycling test, the percentage of leached core materials from MePCMs with interpenetrating shell was approximately one-third of that from MePCMs with particles-embedded shell. The results showed that MePCMs with an integral shell presented better thermal stability, tightness and thermal reliability than MePCMs with particles-embedded shell. The research developed a simple process for MePCMs with excellent performance.     

泡沫金属相变材料熔化传热过程的数值分析

以泡沫金属为基体,孔隙中填充相变材料制成的蓄热材料为研究对象,利用FLUENT凝固/熔化模型对填充和未填充泡沫金属的两种相变材料制成的蓄热球的相变传热过程进行数值模拟研究,得到了蓄热球传热过程的温度场分布、相界面移动规律。研究表明与未填充泡沫金属相变材料的蓄热球相比,填充泡沫金属相变材料的蓄热球能显著缩短其熔化时间并提高相变材料内部温度均匀性,从而能提高蓄热装置的蓄热速率,对相变问题的数值模拟以及相变蓄能装置的设计具有重要的参考价值。     

Effect of microencapsulated phase change materials on the thermo-mechanical properties of poly(methyl-methacrylate) based biomaterials

Microencapsulated paraffin based phase change material (PCM) have been incorporated into Poly(methyl-methacrylate) (PMMA) matrix in order to enhance the thermo-mechanical properties. Calorimetric and mechanical analyses are carried out and the thermo regulating potential of PMMA/PCM composites is investigated. Results indicate that the PCM phase has a negligible effect on the glass transition temperature of the PMMA matrix, and the thermal regulating capability spans around body temperature absorbing or releasing a thermal energy up to 30 J/g. One of the effect of the PCM phase into the cement is the reduction of the peak temperature developed during the exothermal reaction.     

多联机空气源热泵相变蓄能除霜特性试验研究

为了解决多联机空气源热泵常规除霜时间长、室内环境恶化等问题,提出多联机热泵相变蓄能除霜方法。针对提出的新方法,设计系统流程和试验方案,并在模拟室内外环境条件下完成试验研究。相对于常规除霜,新的除霜方法可以有效缩短33.7%的除霜时间,显著改善机组的除霜性能和室内供热环境。     

NaCl和分散剂对相变储能蜡微胶囊制备的影响

以常低温相变储能蜡RT31为芯材,脲醛树脂为壁材,采用原位聚合法制备了相变储能蜡微胶囊.利用傅立叶红外光谱仪、扫描电子显微镜、差示扫描量热仪等对样品进行分析和表征,讨论了助剂NaCl及两种不同类型的分散剂对微胶囊性能和形貌的影响.实验结果表明,加入一定量的NaCl能显著提高微胶囊的相变潜热,使得微胶囊的包封率由75.8%升高到92.5%,在微胶囊成型后期加入一定量的分散剂能明显改善微胶囊的表面形貌和粒径均匀度.     

The durability of cementitious composites containing microencapsulated phase change materials

This study investigates the durability of cementitious composites containing microencapsulated phase change materials (PCMs). First, the stability of the PCM's enthalpy of phase change was examined. A reduction of around 25% in the phase change enthalpy was observed, irrespective of PCM dosage and aging. Significantly, this reduction in enthalpy was not caused by mechanical damage that was induced during mixing, but rather by chemical interactions with dissolved SO₄^2- ions. Second, the influence of PCM additions on water absorption and drying shrinkage of PCM-mortar composites were examined. PCM microcapsules reduced the rate and extent of water sorption; the former was due to their non-sorptive nature which induces hindrances in moisture movement, and the latter was due to dilution, i.e., a reduction in the volume of sorptive cement paste. On the other hand, PCM inclusions did not influence the drying shrinkage of cementitious composites, due to their inability to restrain the shrinkage of the cement paste. The results suggest that PCMs exert no detrimental influences on, and, in specific cases, may even slightly improve the durability of cementitious composites.     

复合相变材料储热水泥板的热性能研究

以十八烷(OC)为相变材料、膨胀石墨(EG)为支撑结构制备出OC质量含量为90％的十八烷/膨胀石墨复合相变储热材料( OC/EG-PCM).将OC/EG-PCM掺入到普通硅酸盐水泥中,制备出了相变材料质量含量分别为2％、5％、7％、10％的标准储热水泥立方体(70.7×70.7×70.7 mm3)和储热水泥板(10×100×l00 mm3),测量了储热水泥立方体的表观密度和抗压强度,以及储热水泥板的导热系数和储热性能.结果表明,随着OC/EG-PCM质量含量的增加,储热水泥立方体的表现密度和抗压强度逐渐下降,储热水泥板的导热系数也近似于线性减小,储热水泥板的上下表面温差则逐渐增大.当OC/EG-PCM的质量含量为10％时,储热水泥立方体的抗压强度大于10MPa,储热水泥板的上下表面温差大于4.0℃.     

Experimental design of paraffin/methylated melamine-formaldehyde microencapsulated composite phase change material and the application in battery thermal management system

In order to maintain the optimal operating temperature of the battery surface and meet the demand for thermal storage technology,battery thermal management system based on phase change materials has attracted increasing interest.In this work,a kind of core-shell structured microcapsule was synthesized by an in-situ polymerization,where paraffin was used as the core,while methanol was applied to mod-ify the melamine-formaldehyde shell to reduce toxicity and improve thermal stability.Moreover,three different types of heat conductive fillers with the same content of 10 wt.％,i.e.,nano-Al2O3,nano-ZnO and carbon nanotubes were added,generating composites.The microcapsules were uniform,and were not affected by the thermal fillers,which were evenly dispersed around.The composite sample with carbon nanotubes(10 wt.％)showed the highest thermal conductivity of 0.50 W/(m K)and latent heat of 139.64 J/g.Furthermore,according to the leakage testing and battery charge/discharge experiments,compared with Al2O3 and ZnO,the addition of carbon nanotubes remarkably enhances the heat storage ability as latent heat from 126.98 J/g for the prepared sample with Al2O3 and 125.86 J/g for the one with ZnO,then to 139.64 J/g,as well as dissipation performance as a cooling effect by decreasing the sur-face temperature of battery from 2％to 12％of microcapsule,composite sample with carbon nanotubes presents a broad application prospect in battery thermal management system and energy storage field.