Study of Phase-Transition Characteristics of New Composite Phase Change Materials of Capric Acid–Palmitic Acid/Expanded Graphite

Abstract

A new composite phase change material of capric acid–palmitic acid/expanded graphite (CA–PA/EG) with the optimum mass ratio of EG equated to 8:1 was prepared by the physical adsorption method. It was observed that the eutectic point of CA–PA binary system was reached at 22.1 °C, and CA–PA was uniformly distributed into the pores of EG by physical interaction. The melting and freezing temperatures of CA–PA/EG obtained by differential scanning calorimeter (DSC) were 23.05 and 20.82 °C, respectively, while the corresponding latent heats were 139.7 and 131.8 J/g, respectively. It had good thermal and chemical stability, and there was almost no leakage of liquid binary phase change materials after 1000 melting–freezing cycles. According to the experimental results of the thermogravimetry (TG) analyzer as well as heat storage and release, CA–PA/EG has excellent thermal reliability and heat resistance and the high thermal conductivity of EG promotes the thermal energy storage and release rate of CA–PA. Thus, CA–PA/EG is suitable as a phase change energy storage material for building energy conservation.

Preparation and Thermal Performance of Fatty Acid Binary Eutectic Mixture/Expanded Graphite Composites as Form-Stable Phase Change Materials for Thermal Energy Storage

“…Fei et al prepared capric–palmitic acid/expanded graphite (CA–PA/EG) with the EG optimum mass content of 11.1%; the results confirmed that the addition of EG may enhance the heat conductivity together with boosting the heat storage/release speed of CA–PA, and the CA–PA/EG CPCM with the optimum mass ratio provides superior heat stableness and chemical stability . Huang et al prepared the pahnitic acid–stearic acid/bentonite/expanded graphite CPCMs with bentonite used as the supporting material and expanded graphite used to prevent eutectic mixtures from leaking while also improving the thermal conductivity of the CPCMs, and the experimental results of heat storage/release show that the heat transfer of the CPCMs with EG is enhanced .…”

“…27−30 Fei et al prepared capric−palmitic acid/expanded graphite (CA−PA/EG) with the EG optimum mass content of 11.1%; the results confirmed that the addition of EG may enhance the heat conductivity together with boosting the heat storage/ release speed of CA−PA, and the CA−PA/EG CPCM with the optimum mass ratio provides superior heat stableness and chemical stability. 31 graphite used to prevent eutectic mixtures from leaking while also improving the thermal conductivity of the CPCMs, and the experimental results of heat storage/release show that the heat transfer of the CPCMs with EG is enhanced. 32 Sari prepared bentonite-based form-stable composite PCMs (Bb-FSPCMs) with an EG mass content of 5 wt % and found that the addition of EG enhanced the heat transfer performance.…”

Shape-stable composite phase change materials encapsulated by lignin-based ordered porous carbon for thermal energy storage

“…Compared to inorganic PCMs, organic PCMs have many advantages such as low supercooling, no phase separation, chemical stability, weak corrosiveness and recyclability [7,8] . However, the risk of leakage during solid-liquid transformation is the main drawback of organic phase change materials, which limits their application in practice [9,10] . Microcapsule coating techniques, polymer moulding techniques and adsorption of porous carrier materials were used to prepare shapestable composite phase change materials in order to overcome the leakage problems of organic phase change materials [11,12] .…”

Preparation and Thermal Properties of a New Low Eutectic Mixture of Myristic Acid–Palmitic Acid–Tetradecanol

“…With the increasing demand for energy and the depletion of traditional fossil energy, the energy crisis is becoming more and more serious. − When the ambient temperature changes in the field of construction, the phase-change materials (PCMs) can store and release heat by changing the phase state. The combination of phase-change materials and common building materials could increase the indoor heat transfer, reduce the inflow or outflow of outdoor heat, and maintain the stability of the indoor environment temperature. − Fatty acids as phase-change materials have the advantages of nontoxic and rich resources, − but the melting point of most single fatty acid alcohols is above 40 °C, which cannot be directly used in building structures. − The combination of fatty acids and fatty alcohols can overcome respective shortcomings, produce synergistic effect, obtain phase-change materials suitable for low-temperature energy storage, and broaden the application range of fatty acids and fatty alcohols.…”