Constructing Of Composite Phase Change Materials From Vanadium-bearing Stone Coal

Phase change thermal storage technology is widely used in solar thermal utilization,building energy conservation,and industrial waste heat recovery.This actively promotes the efficient and clean use of energy.However,the phase change materials have problems such as easy leakage,low thermal conductivity,and poor thermal stability,which limit the wide range of use of phase change thermal storage technology.China has rich reserves of vanadium-bearing stone coal,which has certain thermal storage characteristics and key elements.In this paper,vanadium-containing stone coal(SC)is used as the main raw material,and its mineral structure and vanadium are fully utilized to construct a variety of composite phase change materials.Also,preliminary research on its application is carried out.(1)It analyzed the mineralogical characteristics and thermal storage characteristics of two vanadium-bearing stone coals.The mineralogical characteristics of these two kinds of stone coals are analyzed by XRD,XRF,FTIR,and other methods.These two different stone coals(SCwt and SChc)were used as the matrix and stearic acid(SA)was used as the phase change thermal storage medium to construct composite phase change materials(SA/SCwt and SA/SChc)by the vacuum impregnation method.By comparing the microscopic morphology,crystal structure,and chemical composition of the materials before and after the composite,it was proved that SA was successfully loaded into SC and the composite had good chemical stability.The result of research provides basic data for the extraction of vanadium from stone coal and confirms the feasibility of using stone coal as a raw material to prepare composite phase change materials.(2)It revealed the regulation mechanism of the thermal storage behavior of stone coal-based composite materials.By using stearic acid(SA)as the phase change thermal storage medium,the performance-enhanced stone coal-based composite phase change materials(PCMs)were prepared by the vacuum impregnation method.After roasting and acid leaching,stone coal was used as the support matrix of the composite phase change material(the best sample SC1L was screened through the single factor experiment).Compared with the raw ore,the stone coal after roasting and acid leaching have a higher loading capacity.To improve the thermal conductivity of the material,a certain proportion of expanded graphite(EG)was added to stone coal to obtain composite phase change materials(SA/SC1L/EG).The analysis of the results showed the thermal conductivity of SA/SC1L/EG0.1 is 2.6 times that of SA/SC1L.The thermal infrared image shows that after adding EG,the transient temperature response of composite was enhanced.(3)It constructed different crystalline VO2 phase change materials and explored their infrared adaptive stealth capabilities.Three crystal forms of VO2 were prepared by the hydrothermal reduction method.XRD,FTIR,and SEM were used to compare the crystal characteristics,chemical structure,and surface morphology of the three crystal forms of VO2.The thermal behavior of the three crystal forms of VO2 was analyzed by TG and DSC.The thermal infrared reaction properties of three crystal forms of VO2 under constant temperature were studied by using an infrared thermal imager.The prepared VO2/stone coal-based composites were compared with VO2 to evaluate their self-adaptive thermal infrared stealth ability.This paper analyzed the mineralogical characteristics and thermal storage characteristics of vanadium-bearing stone coals and constructed a series of composite phase change materials by using interdisciplinary knowledge of energy science,materials science,mineral processing,and military technology.Also,its application in infrared adaptive stealth was explored.It provided a new idea for the preparation and application of thermal storage mineral materials.