UiO-66 is a potential material for adsorption heat transformation(AHT)with high specific surface area,and excellent thermal and chemical stability.However,the low water adsorption capacity of UiO-66 in the low relativ...UiO-66 is a potential material for adsorption heat transformation(AHT)with high specific surface area,and excellent thermal and chemical stability.However,the low water adsorption capacity of UiO-66 in the low relative pressure range(0<P/P_(0)<0.3)limits its application in AHT.We prepare the UiO-66 modified by MgCl_(2)through using the solvothermal method and impregnation method,and study their water vapor adsorption performances and heat storage capacities.Attributed to the extremely high saturated water uptake and excellent hydrophilicity of MgCl_(2),the water adsorption performance of UiO-66 is improved,although the introduction of MgCl_(2)reduces its specific surface area and pore volume.The water adsorption capacity at P/P_(0)=0.3 and the saturated water adsorption capacity of the UiO-66(with MgCl_(2)content of 0.57 wt%)modified by the solvothermal method are 0.27 g/g and 0.57 g/g at 298 K,respectively,which are 68.8%and 32.6%higher than the counterparts of pure UiO-66,respectively.Comparing with pure UiO-66,the water adsorption capacity of the UiO-66(with MgCl_(2)content of 1.02 wt%)modified by the impregnation method is increased by 56.3%and 14.0%at the same pressure,respectively.During 20 water adsorption/desorption cycles,the above two materials show high heat storage densities(~1293 J/g and 1378 J/g).Therein,the UiO-66 modified by the solvothermal method exhibits the excellent cyclic stability.These results suggest that the introduction of an appropriate amount of MgCl_(2)makes UiO-66more suitable for AHT applications.展开更多
选用13X型沸石和水作为工质对,采用直接接触换热法,研究操作参数对利用低品位余热直接生成高温蒸汽系统性能的影响。当进水温度从65℃升至85℃时,制热系数COP_h(coefficient of performance for heating)提高24.45%;当干燥气温度由110...选用13X型沸石和水作为工质对,采用直接接触换热法,研究操作参数对利用低品位余热直接生成高温蒸汽系统性能的影响。当进水温度从65℃升至85℃时,制热系数COP_h(coefficient of performance for heating)提高24.45%;当干燥气温度由110℃升至150℃时,蒸汽最高温度提高45℃,系统温升提高21℃,生成蒸汽质量提高89.25%。结果表明:降低干燥气湿度、提高沸石初始温度、进水温度、干燥气温度,均能够提高生成蒸汽最高温度和质量。提高进水速率,适当减少干燥时间可以增大循环过程的制热效率SHP(specific heating power)。展开更多
This paper reports that OH^- absorption bands of lithium niobate crystal have been measured at room temperature, and the band shape depending on the crystal composition has been observed. The OH^- absorption bands are...This paper reports that OH^- absorption bands of lithium niobate crystal have been measured at room temperature, and the band shape depending on the crystal composition has been observed. The OH^- absorption bands are fitted with three Lorentzian peaks by varying position, halfwidth, and height. Nearly constant peak positions （3468, 3481 and 3490 cm^-1） are obtained for all samples. It shows that the height and area of the decomposed peaks vary with the Li composition in a complex way. However, the combinations of these fitting parameters show a linear dependence on the composition up to nearly 50 mol%, which is very useful for the composition determination in a wide range. The linear relationships between the parameter combinations and Li composition are also presented quantitatively. In addition, the explanations were given for the excellent composition linearity of parameter combinations.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51836009)。
文摘UiO-66 is a potential material for adsorption heat transformation(AHT)with high specific surface area,and excellent thermal and chemical stability.However,the low water adsorption capacity of UiO-66 in the low relative pressure range(0<P/P_(0)<0.3)limits its application in AHT.We prepare the UiO-66 modified by MgCl_(2)through using the solvothermal method and impregnation method,and study their water vapor adsorption performances and heat storage capacities.Attributed to the extremely high saturated water uptake and excellent hydrophilicity of MgCl_(2),the water adsorption performance of UiO-66 is improved,although the introduction of MgCl_(2)reduces its specific surface area and pore volume.The water adsorption capacity at P/P_(0)=0.3 and the saturated water adsorption capacity of the UiO-66(with MgCl_(2)content of 0.57 wt%)modified by the solvothermal method are 0.27 g/g and 0.57 g/g at 298 K,respectively,which are 68.8%and 32.6%higher than the counterparts of pure UiO-66,respectively.Comparing with pure UiO-66,the water adsorption capacity of the UiO-66(with MgCl_(2)content of 1.02 wt%)modified by the impregnation method is increased by 56.3%and 14.0%at the same pressure,respectively.During 20 water adsorption/desorption cycles,the above two materials show high heat storage densities(~1293 J/g and 1378 J/g).Therein,the UiO-66 modified by the solvothermal method exhibits the excellent cyclic stability.These results suggest that the introduction of an appropriate amount of MgCl_(2)makes UiO-66more suitable for AHT applications.
文摘选用13X型沸石和水作为工质对,采用直接接触换热法,研究操作参数对利用低品位余热直接生成高温蒸汽系统性能的影响。当进水温度从65℃升至85℃时,制热系数COP_h(coefficient of performance for heating)提高24.45%;当干燥气温度由110℃升至150℃时,蒸汽最高温度提高45℃,系统温升提高21℃,生成蒸汽质量提高89.25%。结果表明:降低干燥气湿度、提高沸石初始温度、进水温度、干燥气温度,均能够提高生成蒸汽最高温度和质量。提高进水速率,适当减少干燥时间可以增大循环过程的制热效率SHP(specific heating power)。
基金Project supported by Natural Science Foundation of Hebei Province of China (Grant No F2007000119)Scientific Research Foundation of Education Bureau of Hebei Province of China (Grant No 2008113)+1 种基金Technology Development Foundation of Higher Educational Institutions of Tianjin of China (Grant No 20070502)the Natural Science Foundation of Tianjin in 2009
文摘This paper reports that OH^- absorption bands of lithium niobate crystal have been measured at room temperature, and the band shape depending on the crystal composition has been observed. The OH^- absorption bands are fitted with three Lorentzian peaks by varying position, halfwidth, and height. Nearly constant peak positions （3468, 3481 and 3490 cm^-1） are obtained for all samples. It shows that the height and area of the decomposed peaks vary with the Li composition in a complex way. However, the combinations of these fitting parameters show a linear dependence on the composition up to nearly 50 mol%, which is very useful for the composition determination in a wide range. The linear relationships between the parameter combinations and Li composition are also presented quantitatively. In addition, the explanations were given for the excellent composition linearity of parameter combinations.
