Preparation of Palygorskite-based Phase Change Composites for Thermal Energy Storage and Their Applications in Trombe Walls

Palygorskite/paraffin phase-change composites were prepared by the combination of purified palygorskite clay and sliced paraffin. Then, this composite was used in the Trombe wall to improve its energy storage ability. Further, its energy storage ability was compared to that of ordinary concrete wall through contrastive test. The experiments show that palygorskite clay is a type of clay mineral with strong adsorption ability, and the purity of natural palygorskite clay can reach up to 97.1% after certain purification processes. Paraffin is well adsorbed by palygorskite, and the test results show that the optimal adsorption ratio is palygorskite： paraffin = 2：1（mass ratio）. Palygorskite/paraffin phase change composites can be obtained by using palygorskite as the adsorbing medium to adsorb paraffin. The composite materials exhibit good heat storage（release） performance, which can store heat with increasing environment temperature and release heat with decreasing temperature. This property not only increases the inertia to environment temperature change, but also promotes the energy migration in different time and space, thus achieving a certain energy-saving effect. The application of palygorskite/paraffin phase change composite materials to the Trombe wall can significantly reduce the fluctuation of indoor temperature and enhance the thermal inertia of indoor environment. From the aspect of energy storage effect, the Trombe wall fabricated using PCMs is significantly superior to the concrete wall with the same thickness.

Preparation of Paraffin/γ-Al2O3 Composites as Phase Change Energy Storage Materials

Paraffin/γ-Al2O3 composites as phase change energy storage materials were prepared by absorbing paraffin in porous network of γ-Al2O3.In the composite materials,paraffin was used as a phase change material(PCM)for thermal energy storage,and γ-Al2O3 acted as supporting materials.Characterizations were conducted to evaluate the energy storage performance of the composites,and differential scanning calorimeter results showed that the PCM-3 composite has melting latent heat of 112.9 kJ/kg with a melting temperature of 62.9 ℃.Due to strong capillary force and surface tension between paraffin and γ-Al2O3,the leakage of melted paraffin from the composites can be effectively prevented.Therefore,the paraffin/γ-Al2O3 composites have a good thermal stability and can be used repeatedly.

Structure,Characterization and Thermal Properties of the Form-Stable Paraffin/High-Density Polyethylene/Expanded Graphite/Epoxy Resin Composite PCMs for Thermal Energy Storage

The form-stable paraffin/high-density polyethylene/expanded graphite/epoxy resin composite phase change materials(CPCMs),exhibiting suitable thermal properties,including low melting temperature,high conductivity and high phase change enthalpy,was developed in this work.Herein,paraffin(PA)was utilized as a core PCM.High-density polyethylene(HDPE)was utilized for the shape stabilization and preventing the PCMs leakage.Expanded graphite(EG)was used to increase its thermal conductivity and act also in the porous supporting material.Epoxy resin(ER)was used to provide flexible encapsulated scaffold morphology and keep a highly tight network structure of the PCMs.However,the physical architecture,the chemical architecture and thermal behavior properties of specimens were investigated by using the spectroscopy and calorimetry techniques.The scanning electron microscope(SEM),X-ray diffraction(XRD)and fourier transform infrared spectrometer FTIR tests have shown good uniformity structure and good compatibility of components.In addition,the thermal conductivity tests revealed that the thermal conductivity of PA,initially 0.31 W/(m·K)improved up to 1.9 times by adding the 6 wt%mass fraction of EG in composite PCMs.Furthermore,the differential scanning calorimeter(DSC)measurements indicated that PA melting enthalpy,initially 231 J/g decreased up to 125 J/g with the increase of the amount of HDPE which was due to the limitation caused by the atomic network constructed by the base material.The thermogravimetric analyzer(TGA)and leakage-proof revealed the enhancement of the degradation of PA with the raise of amount of the HDPE into the CPCMs.Therefore,the proposed form-stable CPCMs are a great candidate for the thermal regulation and thermal energy storage employment.

Experimental study and assessment of thermal energy storage mortar with paraffin/recycled brick powder composite phase change materials

Thermal energy storage recycled powder mortar(TESRM)was developed in this study by incorporating paraffin/recycled brick powder(paraffin/BP)composite phase change materials(PCM).Fourier transform infrared and thermogravimetric analysis results showed that paraffin/BP composite PCM had good chemical and thermal stability.The onset melting temperature and latent heat of the composite PCM were 46.49°C and 30.1 J·g−1.The fresh mortar properties and hardened properties were also investigated in this study.Paraffin/BP composite PCM with replacement ratio of 0%,10%,20%,and 30%by weight of cement were studied.The results showed that the static and dynamic yield stresses of TESRM were 699.4%and 172.9%higher than those of normal mortar,respectively.The addition of paraffin/BP composite PCM had a positive impact on the mechanical properties of mortar at later ages,and could also reduce the dry shrinkage of mortar.The dry shrinkage of TESRM had a maximum reduction about 26.15%at 120 d.The thermal properties of TESRM were better than those of normal mortar.The thermal conductivity of TESRM was 36.3%less than that of normal mortar and the heating test results showed that TESRM had good thermal energy storage performance.

Preparation of Microcapsules Containing Phase Change Material and Silicon Carbide Powder with Interfacial Polycondensation Reaction Method

The fundamental experiments were performed to establish the operational conditions required to prepare the microcapsules containing paraffin wax as a phase change material (PCM) and SiC powder with the interfacial polycondensation reaction. It was investigated how SiC powder affected a few characteristics of microcapsules such as the diameters of microcapsules, latent heat storage density, thermal responsibility and supercooling. In the experiment, the concentration of oil soluble surfactant, the revolution speed of impeller for preparing the (O/W) emulsion and the added weight of SiC powder were changed stepwise. The microcapsules containing PCM in which SiC powder was dispersed could be prepared well and characterized. The diameters of microcapsules increased by containing SiC powder and the content of SiC powder could be increased by performing surface modification of SiC powder. Latent heat storage density decreased with the content of SiC powder. Supercooling of PCM and thermal responsibility could be improved to some degree by containing SiC powder.

新型复合相变储能材料Na/Paraffin的制备与性能分析

为提升广泛应用于相变储能领域的石蜡的导热系数,在手套箱内将导热系数高、熔点低、密度小的金属Na与石蜡复合为Na/paraffin新型相变储能材料,并对其导热系数、相变潜热及储/放热特性进行研究。结果表明:5%Na/95%paraffin复合相变储能材料导热系数较纯石蜡提高了17.6倍,储/放热速率均较纯石蜡提升了1倍;经过200次循环实验后,3%Na/97%paraffin复合相变储能材料相变温度由60.58℃下降到59.65℃,相变潜热由166.7520J·g^(-1)下降到160.5632J·g^(-1),热导率由2.33W·m^(-1)·K^(-1)减少到1.98W·m^(-1)·K^(-1)。

石蜡基复合相变储能砂浆的制备及性能研究

以石蜡和膨胀石墨为原材料,通过熔融吸附法制备石蜡/膨胀石墨复合相变材料,将相变材料掺入水泥中制备了石蜡基复合相变储能砂浆。通过FT-IR、水化放热测试、SEM、力学和热性能分析,研究了试样的物相结构、微观形貌、力学性能和导热性能。结果表明,石蜡和膨胀石墨是通过物理作用形成了石蜡/膨胀石墨复合相变材料,复合相变材料添加到砂浆中会以颗粒状的形式分散在水泥浆体中,使砂浆表面变得粗糙。相变材料的添加降低了砂浆水化放热速率和水化累积放热量。相变储能砂浆的抗压强度随相变材料的添加不断降低,相变材料添加量20%的储能砂浆的抗压强度为最低值10.63 MPa,较纯砂浆降低了34.18%,密度和导热系数降低至最小值,分别为1730.2 kg/m^(3)和0.372 W/(m·K);蓄热系数和比热容达到最大值,分别为16.24 W/(m^(2)·K)和1.592 J/(kg·℃)。箱体模型动态热性能分析表明,相变材料添加后延缓了最高温度到来的时间,降低了箱体的最高温度,相变材料添加量20%的储能砂浆的最高温度为28.0℃,最高温度到来的时间为8385 s。

膨胀石墨基相变储能材料的制备及性能研究

以膨胀石墨作为主导热材料,石蜡作为相变储热材料,通过真空浸渍法制备了膨胀石墨-石蜡复合相变储能材料,研究了石蜡质量分数对复合相变储能材料微观形貌、物相结构及热性能的影响。结果表明,膨胀石墨和石蜡反应后生成的复合相变储能材料主要依靠物理吸附结合,石蜡均匀覆盖在膨胀石墨的表面以及孔隙中,当石蜡质量分数为91%时,复合相变储能材料的密封性和结构致密性最佳,几乎不发生泄露。随着石蜡质量分数的增加,复合相变储能材料的熔点逐渐增大,热分解温度逐渐提高,石蜡质量分数91%的复合相变储能材料相比石蜡质量分数85%的相变材料热分解温度提高了约15℃。随着石蜡质量分数的增大,复合相变储能材料的导热系数和热扩散系数持续降低,密度先降低后增加,比热持续增大。当石蜡质量分数为94%时,复合相变储能材料的导热系数和热扩散系数均为最低值,分别为2.492 W/(m·K)和0.605 mm^(2)/s;当石蜡质量分数为91%时,复合相变储能材料的密度为最小值0.794 g/cm^(3),对应比热为5.462 J/(g·K)。分析可得,石蜡质量分数为91%的复合相变储能材料的综合性能最佳。

Microencapsulation of n-Eicosane as Energy Storage Material

For heat energy storage application, polyurea microcapsules containing phase change material, n-eicosane, were synthesized by using interfacial polymerization method with toluene-2,4-diisocyanate (TDI) and diethylenetriamine (DETA) as monomers in an emulsion system. Poly(ethylene glycol)octyl-phenyl ether (OP), a nonionic surfactant, was the emulsifier for the system. The experimental result indicates that TDI was reacted with DETA in a mass ratio of 3 to 1. FT-IR spectra confirm the formation of wall material, polyurea, from the two monomers, TDI and DETA. Encapsulation efficiency of n-eicosane is about 75%. Microcapsule of n-eicosane melts at a temperature close to that of n-eicosane, while its stored heat energy varies with core material n-eicosane when wall material fixed. Thermo-gravimetric analysis shows that core material n-eicosane, micro-n-eicosane and wall material polyurea can withstand temperatures up to 130, 170 and 250 ℃, respectively.

相变微胶囊的制备及其在热储能中的应用进展

相变材料因高能量存储密度、高潜热和良好的热稳定性被广泛应用于潜热储能,但是泄漏、热导率低等问题限制了相变材料在热储能中的应用。微囊化能够防止相变材料的泄漏,降低与外界环境的反应并提高热导率,因此相变微胶囊是提高相变材料导热性和解决泄漏等问题的有效方法。介绍了相变微胶囊常见的制备方法及其在建筑材料、太阳能储能及热管理系统中的应用,并展望了该材料未来的发展趋势。

高储能性石蜡相变微胶囊的微流控制备与性能研究

高储能性相变微胶囊的可控制备对于相变潜热的高效利用具有重要意义。基于此,利用微流控技术,分别以石蜡和碳纳米管(CNT)复合海藻酸钠为芯材和壳材,通过乳化固化法制备得到了石蜡相变微胶囊,并研究了CNT含量对相变微胶囊性能的影响规律。结果表明:随着壳层中CNT含量的不断增加,微胶囊对石蜡的包封能力显著提高,当其含量为3%时,石蜡相变微胶囊的包封率接近96%,热焓值达206.8J/g。同时,石蜡相变微胶囊的光热转换能力也随CNT含量的增加而增强,并在光照11min后,其温度可达47℃。相关研究结果可为可控制备具有高储能性和光热转换性能的相变微胶囊提供科学指导。

离子交联型石蜡基导热增强定型相变材料的制备及其性能

对石蜡(PA)进行接枝改性、自乳化得到PA乳液。在乳液颗粒形态下将接枝产物分散在乳化层,常温条件下通过乳液颗粒间的空间分布及离子交联,对导热材料形成内锁、铆结,并加Cu粉增强导热制备了PA基导热增强定型相变材料(记作PA@Cu),与定量PA于80℃浸渍吸附20 min,得到吸附PA的PA@Cu(记作PA@Cu-PA),并研究了其元素结构、表观形貌、相变焓、导热性能、热稳定性。结果表明:当Cu粉用量为16 g时,PA@Cu-PA导热系数0.468 W/(m·K),结晶焓-133.27 J/g,在85℃时无明显泄漏,热分解温度384.5℃,储能性能与热稳定性能良好。

n-C_(20)@TiO_(2-x)相变微胶囊及其调温羽绒的制备与性能

通过溶胶-凝胶法制备了以二氧化钛(TiO_(2))为壳材、正二十烷(n-C_(20))为芯材的相变微胶囊n-C_(20)@TiO_(2),利用水合肼(N_(2)H_4·H_(2)O)溶液对其外壳TiO_(2)进行还原反应得到了微胶囊n-C_(20)@TiO_(2-x),随后以水性聚氨酯(WPU)为介质,将羽绒(DF)与n-C_(20)@TiO_(2-x)结合制得蓄热调温羽绒n-C_(20)@TiO_(2-x)/DF.采用傅里叶变换红外光谱(FTIR)、场发射扫描电子显微镜(FESEM)、X射线衍射仪(XRD)、X射线光电子能谱(XPS)和差示扫描量热仪(DSC)等对相变微胶囊及n-C_(20)@TiO_(2-x)/DF的形貌结构和热性能进行表征.结果表明,n-C_(20)@TiO_(2-x)粒径约为309 nm,热焓值由改性前的80.2 J/g(n-C_(20)@TiO_(2))提升至106.1 J/g,并呈现出优异的热稳定性.当n-C_(20)@TiO_(2-x)添加量为30%时制备的调温羽绒热焓值为18.7 J/g,且经过5次水洗后仍可达到10.6 J/g.本实验为微胶囊的改性与功能性羽绒材料的研究提供了一种策略,有利于相变材料在传统纺织领域的拓展应用.

碳基纳米石蜡复合相变储能材料制备与性能研究

相变材料的低导热系数限制了相变储能系统的传热效率。本工作针对石蜡导热系数低的问题,以石蜡为基底材料,选取羧基化多壁碳纳米管(MWCNT)与纳米洋葱碳(CNOs)作为高导热介质,采用两步法分别制备了系列不同质量浓度的碳基纳米石蜡复合相变材料(CPCM),探究了两种纳米材料的添加量对CPCM的相变温度、相变潜热、导热系数和运动黏度的影响。研究结果发现,碳纳米材料的加入对石蜡的相变温度的影响较小,最大温度偏差仅为1.811℃;相变潜热随着纳米颗粒质量浓度变化呈现非线性变化趋势,CNOs质量分数为4%时,CPCM潜热减少最多,达到16.4%;CPCM的导热系数和液相材料的运动黏度均随着纳米添加剂浓度的增加而增加,4%CNOs-PCMs材料液态和固态导热系数分别为0.3167 W/(m·K)和0.8322 W/(m·K),导热系数增幅最大,达到80.7%和195.9%,与MWCNT相比,使用CNOs作为石蜡的高导热介质,更有利于增强复合相变材料的导热性能。本研究为开发具有高导热系数的石蜡复合相变材料提供了实验依据,为不同需求下纳米石蜡复合相变材料的选择提供了参考。

生物基多孔炭复合相变材料的制备及性能研究

以野生雏菊茎秆为原料,通过高温碳化和化学改性得到层次化多孔骨架材料,在多孔骨架材料中真空浸渍石蜡制备了形状稳定的生物基复合相变材料。利用乙醇进行化学改性后,孔隙结构更丰富,复合相变材料的焓值增加。制备的生物基多孔炭复合相变材料相变焓为213.6J/g,相变温度为40.1℃,具有良好的热稳定性、化学稳定性和循环稳定性。将生物基多孔炭复合相变材料集成到模拟建筑中,研究了其热管理性能。结果表明,在模拟光照下,相变房屋具有明显的热缓冲作用,该复合相变材料在热管理方面具有巨大的应用潜力。

SiO_(2)基复合相变微胶囊的制备及其在电池热管理中的应用研究

研究了3种沉淀剂对合成SiO_(2)基复合相变微胶囊的形貌特征和相变储热性能的影响。通过红外光谱仪(FT-IR)、X射线衍射仪、导热系数测定仪等对SiO_(2)基复合相变微胶囊的组成、结构和导热性能进行分析。结果表明,正十八烷与SiO_(2)壳材仅是物理结合,两者并未发生化学反应;当沉淀剂为盐酸时所制备的SiO_(2)基复合相变微胶囊分散性良好,包覆率和储能效率可达69%,导热系数提高近50%。SiO_(2)基复合相变微胶囊对锂离子电池组热管理测试结果表明,微胶囊能有效控制电池组的表面温度,且温度波动范围小。

正十六烷聚脲微胶囊化相变材料(英文)

用界面聚合法,合成了直径大约2.5μm可用于热能储存含相变材料的聚脲包覆微胶囊.在含乳化剂的水溶液中,将溶有芯材正十六烷的有机相乳化成微米级油性液滴,随后加入的水溶性单体二胺与甲苯2,4-二异氰酸酯在胶束界面相互反应形成囊壁.分别用乙烯二胺,1,6-己二胺和它们的混合物作为水溶性单体进行了研究.并用红外光谱和热分析分别考察了不同胺类对微胶囊化学结构和热性质的影响.红外谱图显示合成了聚脲微胶囊,热重曲线表明含正十六烷的聚脲微胶囊能够耐受大约300℃高温,差示扫描量热测试表明所有样品均具有合适的相转变热,冷热循环实验揭示微胶囊能够维持储热容量不衰减.研究表明微胶囊化的正十六烷作为相变储热材料具有良好的应用前景.

UF/石蜡储能微胶囊的制备与表征

以石蜡为囊芯,尿素-甲醛树脂为囊壁,运用原位聚合法合成相变储能微胶囊材料.采用光学显微镜观察微胶囊形成过程,扫描电子显微镜观察微胶囊的表面形貌和壁厚,用红外光谱仪表征微胶囊的化学成分,用差示扫描量热仪研究微胶束相变储能性能.研究表明,脲醛树脂可有效包覆石蜡,形成粒径分布均匀的相变储能微胶囊,该材料具有储能效果,可用于设计储能建筑材料.

相变储热微胶囊的研制

采用原位聚合法用三聚氰胺甲醛树脂包覆一种相变点为24℃相变材料A,制得相变储热微胶囊。利用激光粒径分布仪、SEM、DSC和TG分别研究了微胶囊的粒径分布、表面形态及热性能的影响因素。实验结果表明,所得微胶囊粒径分布均匀,表面光洁,具有很好的致密性和一定的强度。其中当乳化速度大于3500r/min、乳化时间为5min、壁材滴加速度小于0.5mL/min且系统调节剂为芯材的30%～40%时,微胶囊的粒径分布集中;DSC显示微胶囊包覆相变材料不影响其相变点,相变储热明显。此种微胶囊中由于含有相变材料,而相变材料在发生相变时具有调温功能,应用于室内墙体材料中,可使墙体材料具有自调温作用。

石蜡／膨胀石墨复合相变储热材料的研究

以膨胀石墨为基体,石蜡为相变储热介质,利用膨胀石墨对石蜡良好的吸附性能,制备出了石蜡／膨胀 石墨复合相变储热材料。由于毛细作用力和表面张力的作用,石蜡在固-液相变时,很难从膨胀石墨的微孔中渗 透出来。实验结果表明,石蜡/膨胀石墨复合相变储热材料没有改变膨胀石墨的结构和石蜡的固-液相变温度, 且其结合了石墨高的导热系数和石蜡大的相变潜热,因而储热密度较高,导热性能好。其相变潜热与对应质量 分率下的石蜡相当,储/放热时间比石蜡明显减少。