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Modern energy batteries are mainly used in pure electric vehicles. The stability of battery operation relies heavily on thermal management systems for which phase-change batteries have become an effective solution. In this study, we designed a battery thermal management system divided into two parts: a shaped phase-change material (PCM) module and a battery module. In the qualitative PCM module, polyethylene glycol was used to absorb heat, expanded graphite (EG) was used as the thermally conductive agent, and copper foam formed the support skeleton. The battery module comprised an 18650 lithium-ion battery with an enthalpy of 155 J/g. In our experiments, we applied PCMs to the battery modules and demonstrated the effectiveness of composite PCM (CPCM) in effectively lowering the temperature of both battery packs and minimizing the temperature discrepancies among individual batteries. At a gradually increasing discharge rate (1C/2C/3C), the battery's Tmax could be lowered and the temperature could be de creased at various positions. It was evident that the battery temperature could be effectively preserved using CPCM. The findings of this study lay a foundation for future research on battery thermal management. Finally, the copper foam and EG contributed significantly to the prevention of leakage. [ABSTRACT FROM AUTHOR]

For a phase-change material (PCM) confined in a porous structure, the interfacial interactions between the PCM and the porous skeleton are the decisive factors in latent heat storage performance. In this work, a novel composite PCM based on hierarchically porous TiO 2 and n-octadecane was successfully synthesized. The porous TiO 2 was prepared by a soft-template method, and the composite PCM was fabricated by introducing n-octadecane under vacuum. Transmission electron microscope and X-ray diffraction (XRD) results revealed that the as-prepared supporting matrix was crystalline TiO 2 , and N 2 adsorption/desorption isotherms indicated that TiO 2 has a hierarchically porous structure. For composite PCMs, Fourier transform infrared spectroscopy and XRD spectra revealed that no chemical bonds were formed between n-octadecane and TiO 2. Scanning electron microscopy results showed abundant n-octadecane enclosed within the nanopores and closely bound on the surfaces of the hierarchically porous TiO 2 , as a result of capillary forces and interfacial tension. Porous TiO 2 exhibited high adsorption for n-octadecane (50 wt%), and the relative enthalpy of the composite PCM was as high as 85.8 J/g. Compared with pure n-octadecane, the thermal conductivity of the as-prepared composite PCMs (e.g., 50 wt% n-octadecane sample) was improved by 138% with the addition of porous TiO 2. After 800 melting/solidifying cycles, the composite PCMs exhibited excellent thermal reliability and high enthalpy. The influence of the TiO 2 pore structure on n-octadecane crystallization behavior is shown in the results. • Hierarchically porous TiO 2 nanomaterial provided an ideal skeleton. • A novel n-octadecane/hierarchically porous TiO 2 composite PCMs was synthesized. • The effect of the nanoporous structure on crystallization is demonstrated. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A 3-layer phase change material configuration was proposed. • A method for temperature selection of phase change material was proposed. • Novel hybrid phase change material wallboards were fabricated and characterized. Abstract Phase change materials are smart, feasible latent heat storage materials and have been incorporated into building materials to reduce energy demand and improve the thermal comfort of buildings. This study proposes a method for improving energy efficiency and thermal comfort in buildings (during both summers and winters) by developing a novel hybrid phase change material wallboard and a method to select the temperature of phase change material for different seasons (29 °C for summer, 18 °C for midseason, and 12 °C for winter). This type of hybrid phase change materials wallboard consists of three types of phase change materials with different phase-change temperatures that can be utilized efficiently in different seasons. The thermal performances of the hybrid phase change material wallboards (two combination modes: Mode1 and Mode2) were evaluated by a guarded hot plate method. The effective thermal conductivity (λ) and apparent specific heat (C p) of these wallboards were investigated. The interior temperature variations of the two types of phase change materials wallboards were compared during heating and cooling, and it could be concluded that the Mode2 hybrid phase change materials wallboard (where phase change material was incorporated into different gypsum wallboard layers) was more suitable for real applications. The goal of this study is to investigate an appropriate method to fabricate a new hybrid phase change materials wallboard for building energy savings over different seasons. [ABSTRACT FROM AUTHOR]

Highlights • A home-made apparatus was developed to measure the thermal characteristics of the PCM-contained wallboard. • The "analogous step method" was proposed to determine the enthalpy of the bulk PCM in gypsum. • Three methods of obtaining H(t) curves were compared and analyzed. Abstract Phase change materials (PCM) as a smart, feasible latent heat storage material has been utilized to reduce the energy demand and improve the thermal comfort of the buildings when incorporated into the building materials. Conventionally, the thermal behavior of the PCM mixed with the solid matrix (mortar or gypsum) is different with the bulk PCM. In this study, we designed an experimental apparatus to characterize the thermal performance of PCMs when they were utilized in their implementation state. Firstly, we investigated the effective thermal conductivity (λ) and the apparent specific heat (C p) of the PCM-contained wallboard and the common gypsum wallboard, which were dependent on the temperature variation. Dynamic method was used to determine the phase change temperature, and the phase change process of the PCMs-wallboard was studied. Then, an "analogous step method" was proposed to determine the H(t) curves of the PCMs-wallboard, and the results were compared with the dynamic method. Finally, three methods of obtaining H(t) curves were compared and analyzed. From the obtained results, it can be concluded that when adopting the dynamic method appropriate heating rate (according to real application scenario) is necessary. When selecting the analogous step method, reducing the temperature interval can increase the accuracy of the H(t) even though it takes a lot of time. Anyway, both ways are more suitable for real wallboard test, comparing with the theoretical calculation method. The goal of our work is to investigate an appropriate method to evaluate the conductivities, apparent heat capacities, H(t) curves, and the phase change temperature of PCM-contained wallboards in their real application. [ABSTRACT FROM AUTHOR]

A novel poly (ethylene glycol)/ZSM-5 composite was fabricated by a simple way, and it was characterized and evaluated for heat energy storage. The composite PCMs was fabricated through introducing PEG to mesoporous pores of ZSM-5 assisted with a vacuum impregnation system. XRD and FTIR analysis results showed that there was no chemical reaction happened between PEG4000 and ZSM-5. DSC and TGA analysis results indicated that the as-prepared PCMs has outstanding latent heats and superb thermal stability. The latent heat of the as-prepared PCMs achieves to 76.37 J/g without any leakiness. Compare with pure PEG, the thermal conductivity of as-prepared PCMs was improved 200%, which means selecting ZSM-5 serve as the supporting material was an effective way to enhance the thermal conductivity. Exudation stability tests results showed that the doping of PEG can reach up 50 wt% without any leakage when the composite undergoing the melting process. According to the above analysis, the prepared composite with good thermal stability, high latent heats and excellent thermal conductivity is very suitable for heat energy storage. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel composition of PCMW was proposed for complex climates. • Energy-saving potential of PCM-based wallboard was investigated for different locations. • The thermal response of PCM-based wallboard in different climates was analyzed. The incorporation of phase-change material (PCM) into construction materials has been proposed to indirectly accomplish indoor thermal comfort and energy saving. To adapt to seasonal changes (e.g., hot summer and cold winter), a novel type of hybrid PCM-containing wallboard (including three different PCMs) was proposed with a wide phase-change temperature range and that can work in various climates. In this study, a small building equipped with a hybrid PCM wallboard was established to evaluate energy-saving performance using EnergyPlus. To compare different hybrid PCM wallboards, four building models were considered, including Mode 1, Mode 2, Mode 3, and gypsum wallboard (BASE). The building performance in terms of heating and cooling energy consumption over one year was investigated at seven locations in China to represent different climate zones. The results show that less heating and cooling energy was required for Mode 2 than for the other models. Further investigation of the Mode 2 PCM wallboard revealed that the location of the PCM layer also influenced the energy savings. The total energy requirements for Mode 2 were lower than those for BASE by 2.15%, 4.33 %, 1.77 %, 5.56 %, 7.65 %, 5.84 %, and 0.2% for Shanghai, Beijing, Kunming, Lanzhou, Xining, Harbin, and Hong Kong, respectively. We conclude that the hybrid PCM wallboard can effectively reduce the heat gain through the building envelope throughout the year, presenting a considerable advantage of using it in buildings located in Shanghai, which experiences a hot summer and cold winter. [ABSTRACT FROM AUTHOR]