This work presents a cost-effective and environment-friendly form-stabilized phase change material(PCM)and corresponding solar thermal application in the tankless solar water heater(TSWH).Coconut shell charcoal(CSC)as...This work presents a cost-effective and environment-friendly form-stabilized phase change material(PCM)and corresponding solar thermal application in the tankless solar water heater(TSWH).Coconut shell charcoal(CSC)as supporting material was modified by moderate oxidant of H_(2)O_(2)with different concentrations,and then sta-bilized stearic acid(SA)to prepare composite PCMs through vacuum impregnation.It found that CSC support causes a 15.70%improvement of SA loadage after treated by 15%H_(2)O_(2)due to coefficient enhancement by phys-ical interaction and surface modification.The modified CSC 15 support appears more super macropores which contribute to the impregnation of SA than non-modified CSC 0 support verifying from SEM and BET results.And the content of oxygen functional groups was increased after oxidation modification,also motivating SA stabiliza-tion by hydrogen bond interaction in XPS analysis.FTIR results proved there is no chemical reaction happened between SA and CSC.Moreover,the latent heat and phase transition temperature of the as-prepared SA/CSC 15 composite are 76.69 J g^(−1)and 52.52℃,respectively.All composites exhibit excellent thermal stability under a working temperature of 180℃and form stability during phase change.Thermal energy storage-release test within 70℃presents the composite has fast heat transfer efficiency than pure SA.The composite filled in TSWH system has 0.75 W m^(−1)K^(−1)thermal conductivity which is 2.88 times higher than that of pure SA(0.26 W m^(−1)K−1).Besides,the TSWH system with a flow rate of 0.004 kg s^(−1)could heat water effectively after sunset and the energy obtained from the thermal storage system within 1830 s testing times is about 0.15 kW h.In all,SA/CSC composite with good physical-thermo properties has potential in thermal energy storage application,especially in solar energy storage.展开更多
MXene具有与金属材料相似的能带结构,并表现出良好的导电性能。但是MXene极易发生层状堆积,影响MXene材料的电化学性能。本研究拟采用MXene和椰壳碳在去离子水中混合制备MXene复合材料,研究其结构和形态对其电化学性质的影响。研究结果...MXene具有与金属材料相似的能带结构,并表现出良好的导电性能。但是MXene极易发生层状堆积,影响MXene材料的电化学性能。本研究拟采用MXene和椰壳碳在去离子水中混合制备MXene复合材料,研究其结构和形态对其电化学性质的影响。研究结果表明,加入到MXene薄膜中的可溶性椰壳炭,通过粒子之间的相互渗透对锂离子的迁移起到促进作用。对该材料进行了充放电实验结果表明,采用质量配比1∶2的材料,在电流密度0.1 A/g条件下,其首次充放电比容量可以达到1951.7 m Ah/g,经过200次循环后,其充放电比容量为800.8 m Ah/g。展开更多
基金This work was supported by the National Natural Science Founda-tion of China(51874047,51504041)the Training Program for Excel-lent Young Innovators of Changsha(kq1802007)+2 种基金the Fund for Univer-sity Young Core Instructors of Hunan Provincethe Outstanding Youth Project of Hunan Provincial Department of Education(18B148)and the Hunan Province 2011 Collaborative Innovation Center of Clean Energy and Smart Grid.
文摘This work presents a cost-effective and environment-friendly form-stabilized phase change material(PCM)and corresponding solar thermal application in the tankless solar water heater(TSWH).Coconut shell charcoal(CSC)as supporting material was modified by moderate oxidant of H_(2)O_(2)with different concentrations,and then sta-bilized stearic acid(SA)to prepare composite PCMs through vacuum impregnation.It found that CSC support causes a 15.70%improvement of SA loadage after treated by 15%H_(2)O_(2)due to coefficient enhancement by phys-ical interaction and surface modification.The modified CSC 15 support appears more super macropores which contribute to the impregnation of SA than non-modified CSC 0 support verifying from SEM and BET results.And the content of oxygen functional groups was increased after oxidation modification,also motivating SA stabiliza-tion by hydrogen bond interaction in XPS analysis.FTIR results proved there is no chemical reaction happened between SA and CSC.Moreover,the latent heat and phase transition temperature of the as-prepared SA/CSC 15 composite are 76.69 J g^(−1)and 52.52℃,respectively.All composites exhibit excellent thermal stability under a working temperature of 180℃and form stability during phase change.Thermal energy storage-release test within 70℃presents the composite has fast heat transfer efficiency than pure SA.The composite filled in TSWH system has 0.75 W m^(−1)K^(−1)thermal conductivity which is 2.88 times higher than that of pure SA(0.26 W m^(−1)K−1).Besides,the TSWH system with a flow rate of 0.004 kg s^(−1)could heat water effectively after sunset and the energy obtained from the thermal storage system within 1830 s testing times is about 0.15 kW h.In all,SA/CSC composite with good physical-thermo properties has potential in thermal energy storage application,especially in solar energy storage.
文摘MXene具有与金属材料相似的能带结构,并表现出良好的导电性能。但是MXene极易发生层状堆积,影响MXene材料的电化学性能。本研究拟采用MXene和椰壳碳在去离子水中混合制备MXene复合材料,研究其结构和形态对其电化学性质的影响。研究结果表明,加入到MXene薄膜中的可溶性椰壳炭,通过粒子之间的相互渗透对锂离子的迁移起到促进作用。对该材料进行了充放电实验结果表明,采用质量配比1∶2的材料,在电流密度0.1 A/g条件下,其首次充放电比容量可以达到1951.7 m Ah/g,经过200次循环后,其充放电比容量为800.8 m Ah/g。
