Energy is the greatest challenge facing the environment. Energy efficiency can be improved by energy storage by management of distribution networks, thereby reducing cost and improving energy usage efficiency. This research investigated the energy efficiency achieved by adding various types of graphite (e.g., flake and amorphous) to organic-based ternary eutectic mixtures like capric acid (CA)–myristic acid (MA)–palmitic acid (PA)-based composite phase change materials (PCMs) under the assistance of ultrasonication to improve thermal properties for thermal energy storage. The graphite was surface modified under a Fresnel lens by using concentration of solar rays, then exfoliation of flake graphite by solar irradiation (xG-F) and exfoliation of amorphous graphite by microwave irradiation (xG-A). For each type of graphite exfoliation, ternary eutectic mixtures with mass concentrations of 5 wt% were prepared. The structure, thermal energy storage properties, and thermal stability of the composite PCM were investigated. Thermal conductivity of the samples in the liquid phase was measured using the transient line source method (KD2Pro). The thermal conductivity was increased by loading xG while energy storage properties were slightly decreased. Furthermore, CA–MA–PA + 5 % xG-F has a slightly modified phase change temperature and enthalpy of melting (T m = 17.5 °C; ΔH m = 143.7 J/g) and freezing (T f = 6.7 °C; ΔH f = 125.5 J/g); this PCM showed higher thermal conductivity of 0.170 W/(m K), representing an increase of up to 114 % relative to the parent material. On the basis of the above results, xG-A was cheaper than xG-F, but they decrease the energy storage capacity according to DSC results obtained at 2 °C/min. CA–MA–PA/xG-F has more potential for use in low temperature energy storage applications.

中文翻译：

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各种石墨对相变材料三元共晶脂肪酸基复合材料导热系数和储能性能的影响

能源是环境面临的最大挑战。通过分配网络的管理，可以通过储能来提高能源效率，从而降低成本并提高能源利用效率。这项研究调查了通过在基于有机的三元共晶混合物（如癸酸（CA）-肉豆蔻酸（MA）-棕榈酸（PA）复合相变）中添加各种类型的石墨（例如片状和无定形）所获得的能效材料（PCM）在超声辅助下改善热能存储的热性能。石墨在菲涅耳透镜下通过使用太阳光线集中进行表面改性，然后通过太阳辐射（xG-F）剥落片状石墨，并通过微波辐射（xG-A）剥落无定形石墨。对于每种类型的石墨剥落，制备了质量浓度为5 wt％的三元共晶混合物。研究了复合PCM的结构，储热性能和热稳定性。使用瞬态线源法（KD2Pro）测量液相中样品的热导率。通过加载xG可以提高热导率，而能量存储性能则略有下降。此外，CA–MA–PA + 5％xG-F的相变温度和熔融焓（T m = 17.5°C；ΔHm = 143.7 J / g）和冻结（T f = 6.7°C； ΔHf = 125.5 J / g）；该PCM显示出更高的导热系数，为0.170 W /（m K），相对于母材而言，增加了高达114％。根据以上结果，xG-A比xG-F便宜，但它们会根据2°C / min的DSC结果降低储能能力。CA–MA–PA / xG-F在低温储能应用中具有更大的潜力。