Mg基相变储热材料设计与热循环中的传热传质行为研究

The high temperature thermal energy storage method, as a technique in solving the matching of energy supply and demand, plays an important role from the points of view of thermal efficience.The thermal energy storage material is the key factor in the thermal energy storage system. One of the main purpose of this investigation is to design series Mg based latent heat storage alloys. The structure and thermal properity of the designed alloys are investigated by corresponding characterization technique. The relationship between the struction and the thermal property such as the heat capacity, thermal conductivity, phase change latent and temperature of the designed materials are investigated to research the influence mechanism of the thermal property.Secondly, the physical and chemical compatibility of the Mg based alloys and container material are also investigated to detemine the high temperature thermal stability and heat corrosion of the designed Mg based phase change thermal storage alloys. Lastly, the evolution of the atomic struction, phase composition and heat storage property during the heating and cooling process is studied to explore the heat and mass transfer hehavior during the thermal cycling. The above investitation is of great importance for the application of the high temperature thermal storage materials in the solar power system.

高温储热技术是太阳能热发电中的重要技术，而高温储热材料的性能是高温储热技术中的关键，直接关系到太阳能热发电的效率和成本。本项目通过研究Mg基高温相变储热材料的结构与相变温度、相变潜热、比热容和热导率等热物理性能的影响机制，建立Mg基相变储热材料结构与热物理性能的对应关系，探索新型金属基高温相变储热材料的构建体系；通过研究Mg基相变储热材料在高温静态下与容器材料的物理化学相容性，探索Mg基相变储热材料的高温热稳定性和热腐蚀性；通过研究Mg基高温相变储热材料在高温热循环过程中原子结构、相组成与储热性能的演变规律，探索金属基高温相变储热材料在高温热循环过程中的传热传质规律，为太阳能热发电技术中金属基高温相变储热材料的应用提供理论依据。

高温储热技术是太阳能热发电中的重要技术，而高温储热材料的性能是高温储热技术中的关键，直接关系到太阳能热发电的效率和成本。金属Mg具有适中的熔点(922K)，较大的熔化焓(368.4J/g)和较高的热导率(156W/(m•K))，是一种潜在的高温相变储热材料。本研究从满足高温储热系统用相变储热材料的性能要求出发，设计了不同成分比的相变温度在450℃～550℃的以Mg为基的Mg-Cu-Zn合金和Mg-Bi高温相变储热材料，通过差式扫描量热法(DSC)及激光脉冲法等方法测试合金的相变温度、相变潜热、比热容、热导率等热物性能。研究结果表明，Mg-Cu-Zn合金的相变温度范围在450℃~500℃之间，满足高温储热系统的工作温度要求。其中Mg-Cu-Zn共晶合金的相变潜热值最大，为238.6J/g。Mg-Cu-Zn合金材料的热导率较高，在95W/(m•K)～145W/(m•K)范围内，并随温度升高呈增大趋势，用于储热材料可以提高换热传热效率。Mg-Bi合金的相变温度范围在545℃~550℃之间, 其中Mg-54%Bi合金的相变潜热值最大，为180.5J/g。通过研究发现，Mg-Bi合金的相变潜热值与其共晶组织的含量存在一定的关系。此外，本研究还对Mg基相变储热材料的热循环稳定性、高温氧化性及与容器材料的相容性进行了研究。研究结果表明， Mg基合金相变储热材料相变温度适宜，相变潜热值高，导热性好，经历多次热循环后热物性依然稳定，加入Be后高温抗氧化性较强，熔融态时与容器材料的相容性良好。