Preparation And Performance Optimization Of Coal Gangue/Steel Slag Composite Heat Storage Materials

Composite phase change heat storage materials can be widely used in the field of the high,medium,and low-temperature heat storage,with the advantages of high energy storage density and low preparation cost,so they are currently the focus of research.Composite phase change heat storage materials are composed of porous matrix and phase change material.The preparation cost and porosity of porous matrix directly affect the comprehensive utilization value of composite materials.To further promote the application of porous ceramics in composite materials,the preparation technology of porous ceramic matrix was preliminarily studied in this paper.In this paper,the solid phase reaction method was used to synthesize ceramic matrix with coal gangue and steel slag as raw materials at different temperatures.On this basis,the microstructure and phase evolution of samples with different raw material mass ratios during the preparation process were studied.The results show that when steel slag is added to raw material for sintering,compared with the pure coal gangue samples without steel slag,the number of pores in the ceramics increases.At the same time,at the higher sintering temperature,some samples with steel slag will melt and deform,which is caused by the presence of anorthite/diopside eutectic.Based on the effects of different mass ratios of gangue/steel slag and different sintering temperatures on the sintered products,the researchers suggest that the best sintering process is:a mass ratio of gangue/steel slag as 1:9 or 9:1,and the sintering temperature is between 1100 ℃ and 1150℃.In order to improve the porosity of porous ceramics of coal gangue/steel slag,the method of adding a pore-forming agent based on the solid phase reaction method was selected.Considering that porous ceramics used in the field of high-temperature fusion need to have interconnected pores,waste cigarette butts were selected as the pore-forming agent to further improve the porosity and pore connectivity of ceramics.The results show that:The raw material powder with the mass ratio of coal gangue/steel slag is 9:1,and the waste cigarette butts with a mass fraction of 50%are added as the pore agent.The porous ceramics sintered at 1100℃ have interconnected tubular pores,the apparent porosity is as high as 72.86%,and the volume density is as low as 0.74 g/cm3.The porous ceramics are composed of quartz,cristobalite,mullite,hematite,anorthite,diopside,etc.,and is composed of good thermophysical properties at room temperature to 800℃,with a maximum specific heat capacity of 1.38 J/(g·K),thermal conductivity and compressive strength also meet the applicable standards of the porous matrix.The composite phase change heat storage material was prepared using the melt infiltration method to combine the porous ceramic of coal gangue/steel slag with solar salt at 300℃.The research results show that:The coal gangue/steel slag porous ceramic matrix has good compatibility with solar salt.The heat storage density of composite phase change heat storage material is up to 1202 kJ/kg,which has good thermal stability at room temperature to 475℃ and can be recycled more than 100 times.