Study On Preparation And Thermal Properties Of Aluminum-doped Iron Ore Material For Sensible Heat Storage

The sensible heat storage technology is a mature and effective means for efficiently and rationally arranging energy and resources and balancing the supply and demand of thermal energy.It has great application potential in many fields including building energy conservation,industrial waste heat recovering and utilization of clean and renewable energy.Among the materials used in this technology,iron ore,which is a solid sensible heat storage material,has caused the national interests of researchers.Iron ore has many advantages,which makes it a good high-temperature heat storage material suitable for using in centralized solar power plants.However,in order to further meet the efficiency requirements of concentrated solar power plants,its thermal performance,especially specific heat capacity and thermal conductivity,needs to be improved.In this paper,we first added pure aluminum powder to natural iron ore according to different proportions,and the aluminum-doped iron ore composite heat storage material was obtained by sintering in air atmosphere.By means of X-ray diffraction technique,scanning electron microscopy,X-ray photoelectron spectroscopy,simultaneous thermal analysis and many other means,the mineral composition,microstructure and thermal properties of the samples were characterized and tested,and then,the possible effect of doped aluminum on the thermal properties of natural iron ore was studied.The results suggest that the specific heat capacity and thermal conductivity of natural iron ore can be greatly improved by doping with aluminum.However,the enhancement effect is closely related to the aluminum content.The best enhancement results are obtained when the dopping amount of aluminum is ranging from 3 to 5 wt.%.With respect to natural iron ore,the specific heat capacity and thermal conductivity of aluminum-doped samples can be increased by up to 36%and 176.1%,respectively.In order to further explore the role of aluminum in the improvement of thermal performance,a sample of 3 wt.%of aluminum was prepared by sintering in a vacuum atmosphere,and a sample of 3 wt.%of alumina was prepared by sintering in an air atmosphere.Through testing and characterization,it is found that the doped aluminum powder will undergo complex physical and chemical reactions with various substances in iron ore,including iron oxide and SiO2.The aluminum ions generated during the reaction will improve the thermal properties of this iron ore material,and compared with the doping mode of aluminum ion provided by direct doping aluminum oxide powder,the doping aluminum powder is more beneficial to the improvement of thermal properties of the sample.In terms of thermal stability,the results of the density,specific heat and thermal conductivity of the A3-1000 sample that was tested from 0 to 500 thermal cycles preliminary show that the sample has good thermal stability.