Under the background of vigorously promoting clean heating, the introduction of phase-change energy storage technology into heating systems has become a new hot issue. In this study, a novel KAl(SO 4 ) 2 ·12H 2 O/expanded graphite (EG) shape-stabilized composite phase-change material (PCM), with a melting temperature of 91.6 °C, latent heat of 245.7 kJ kg −1 , and high heat conductivity of 2.07 W m −1 K −1 , is prepared to manufacture a PCM-based module for space heating. This phase-change electric heating module is developed, and its heat storage and release characteristics are investigated through experimental and numerical studies. The numerical model is validated by experimental results. In view of the numerical simulation, the structure of the module is optimized and its thermal performance is studied. Based on the optimized module, a peak-valley time-of-use (TOU) electric heating module is finally proposed. It is revealed that the module exhibits good thermal performance and is capable of satisfying the indoor heating demand. The effective heat storage and release duration is 8.12 and 15.34 h, which can perfectly realize the operating mode under the “peak-valley TOU electricity” mechanism. In this study, it is demonstrated that peak–valley electric energy storage heating devices have broad prospects in building space heating and provides reference for future application.
Juan Lei,Yan Zhang,Yujing Wang,Xiaoli Ren,Lijun Cheng,Qinqin He,Shuang Wang
In this work, high valence Mo was introduced to prepare amorphous MNC-LDH (MoNiCo-LDH) for constructing crystalline NCO/amorphous MNC-LDH (crystalline NiCo2O4/amorphous MoNiCo-LDH) composite. The prepared sample exhibited a three-dimensional pompom-like structure composed of ultrathin nanoflakes and a hybrid interface between crystalline and amorphous phase, which benefited good electrochemical performance. The synthesized material showed a specific capacity of 841 C/g at 1 A/g, while retaining 82.3% of its initial capacity at 20 A/g. The assembled NCO/MNC-LDH//AC HSC device exhibited an energy density of 58 Wh/kg when the power density was 850 W/kg. It is noteworthy that even at a power density of 8500 W/kg, an energy density of 37.1 Wh/kg could be sustained. The NCO/MNC-LDH//AC retained 76.3% of its initial specific capacitance and 100% coulombic efficiency after 20000 consecutive charge and discharge cycles, demonstrating excellent cycling stability. Furthermore, the ability of two HSCs connected in series to operate small fans and light up LED lights in various colors indicated the practical applications potential. Therefore, the synthesized NCO/MNC-LDH in this work is a favorable candidate material for supercapacitors, which has guiding significance for designing crystalline/amorphous composite materials for energy storage applications.
Qifeng Yang,Liping Liang,Ning Xu,Yang Li,Zhihui Wang,Dadong Shen,Yiming Mo
Electroorganic synthesis has received significant attention due to its environmentally friendly nature, offering the potential to replace traditional hazardous chemical production routes. However, an in-depth technoeconomic analysis (TEA) of electrosynthesis technology is still necessary to objectively assess the economic viability of this technology as an alternative to the traditional chemical synthesis. In this study, we used the cerium-mediated electrosynthesis of 2-methyl-1,4-naphthoquinone (2-MNQ, also known as vitamin K3) as a case study. The process development was conducted in both small-scale and large-scale electrochemical flow cells with 6.25 cm2 and 208 cm2 electrode sizes, respectively, to investigate the process scalability. Under the optimal conditions, a 66% yield was achieved for 2-MNQ with 90% Faradaic efficiency at 50 mA/cm2 current density. We performed a comprehensive TEA on the key factors influencing electroorganic synthesis, including current density, electrode cost and lifespan, membranes, and electricity price. Furthermore, considering ongoing technological advancements in electrodes, membranes, and renewable electricity generation, we analyzed the trend of future projected cost reductions for electrosynthesis processes.
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