Lisheng Tang,Xing Zhao,Changping Feng,Lu Bai,Jie Yang,Ruiying Bao,Zhengying Liu,Mingbo Yang,Wei Yang
The development of solar thermal energy storage technologies associated with phase change materials (PCMs) can greatly improve the utilization efficiency of solar energy, which is of significance to alleviate the global energy shortage. A large number of photodriven shape-stabilized composite PCMs has been exploited in recent decades, while the majorities of studies have demonstrated that the properties of composite PCMs are improved at the expense of energy storage density owing to that the introduced functional materials are substituted for a considerable portion of phase change matrix. Here, three-dimensional (3D) porous skeletons composed of bacterial cellulose (BC) as the supporting material and MXene as the photothermal material are introduced into polyethylene glycol (PEG) to fabricate composite PCMs with excellent comprehensive properties. The obtained composite PCMs show excellent shape stability, efficient photothermal conversion ability and extremely high energy storage capacity , which sheds substantial light on the efficient utilization of solar energy.
Qingyang Luo,Xianglei Liu,Qiao Xu,Yang Tian,Haichen Yao,Jianguo Wang,Shushan Lv,Chunzhuo Dang,Yimin Xuan
Focusing on the development of the next generation latent heat thermal energy storage (TES), molten salt is one of the most promising candidates, while it suffers from small thermal charging rate and low energy storage density. Adding ceramic nanoparticles (NPs) with high thermal conductivity and high chemical stabilities has been proposed to alleviate above problems. However, it’s very challenging to enhance both thermal conductivity and specific heat capacity ( C p ) simultaneously. Besides, induced viscosity increment by NPs will instead reduce the thermal charging rate of TES system, due to suppressed natural convection of molten salts. Herein, concurrent enhancement in solidus thermal conductivity and C p is demonstrated by doping MgO NPs into LiNO 3 /NaCl, which are improved by 63.5 % and 32.3 % at 4 wt%, respectively. The underlying mechanism is attributed to very low interfacial thermal resistance ( R b = 2.424 × 10 −9 K·m 2 ·W −1 ) between MgO and LiNO 3 /NaCl. Benefiting from enhanced C p , the total energy storage density increases from 662.9 J·g −1 to 671.7 J·g −1 for temperature range of 50–300 °C despite decreased phase change enthalpy. The viscosity has a sharp increase from 4.2 cP to 22.4 cP when NPs concentration rises from 0 wt% to 10 wt% at 360 °C. When being applied in TES system, the optimal concentration of MgO NPs is found to be 4 wt%. The thermal charging rate of TES system is suppressed when NPs concentration is too low or too high due to limited thermal conduction and inhibited natural convection, respectively. Viscosity is verified as important as thermal conductivity in system level evaluation. This work helps to guide the design of high-performance molten salts in TES system, so as to achieve both faster thermal charging rate and higher energy storage density.
Although methane-dense storage is anticipated in wet nanoporous materials using the synergy of adsorption and hydration (the so-called adsorption–hydration natural gas, AHNG), the understanding of this technology is still insufficient, which limits its large-scale application. Here, new insights into the AHNG technology are presented, including new findings, phenomena, problems, and solutions, which are helpful to improve the understanding of this technology, enhance methane storage density, and pave the way for its application. Both synergy and antagonism between adsorption and hydration were observed; the synergy increases methane storage capacity, while the antagonism weakens the adsorption and hydration efficiency. In addition, two special phenomena were discussed, which have never been noticed by the hydrate community, and artificial intelligence was thought to provide an effective method for material design, while a storage cell was suggested to improve inner mass transfer of AHNG storage tanks.
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