Abstract:

Micro-size iron powder is a new type of carbon-free energy with great potential. In order to realize large-scale and efficient clean combustion and utilization of metal fuel, it is necessary to master its basic combustion characteristics and chemical reaction kinetics principle. This requires a great deal of research on the chemical kinetics parameters, especially the activation energy. Thermogravimetric analysis (TGA) is the most commonly used tool to obtain kinetic data in experiments, and isotransform kinetic analysis is the most effective method to process the calculation of TGA data. In this paper, six micro-size iron powders of 6, 25, 30, 40, 55, and 120 μm were used to conduct experiments on the thermogravimetric analyzer, and the TGA data are processed and analyzed by Friedman isoconversional method, including the analysis of original TGA data, obtaining conversion data, interpolation of conversion and derivative conversion data, calculating activation energy and conversion function of six kinds of iron powder fitting by Friedman isoconversional method, and comparative analysis of iron powder data with different particle sizes. The results show that in most cases, the smaller the particle size of micro-size iron powder, the more sufficient the reaction is at the same temperature. Before the reaction speed reaches its peak value, the smaller the particle size of iron powder, the faster the reaction speed can get. When the reaction speed reaches its peak value, the smaller the particle size of iron powder, the slower the reaction speed can get. When the conversion is greater than 0.300, for 30, 40, 55, and 120 μm samples, the smaller the particle size of iron powder, the higher the activation energy can get.

Key words: thermogravimetric analysis, micro-size iron powder, oxidation, thermodynamics process, renewable energy, activation energy

摘要：

微米级铁粉是极具潜力的新型无碳固体燃料，为实现金属燃料规模化高效清洁燃烧利用，需要掌握其基础燃烧特性及其化学反应动力学机理。这需要大量关于动力学参数的研究，特别是活化能。热重分析（TGA）是实验获得动力学数据最常用的工具，而等转换动力学分析是处理TGA数据计算的最有效方法。本文利用热重分析仪对6、25、30、40、55及120 μm 6种微米级铁粉进行实验，采用Friedman等转化率对TGA数据进行处理与分析，主要包括TGA数据原始数据分析，获得转化率数据，定转化率数据插值选点，根据Friedman等转化率拟合，计算六种铁粉活化能与转换函数，不同粒径铁粉数据联合对比分析。结果表明大部分情况下，微米级铁粉粒径越小，同温度下反应越充分；在反应速率达到峰值前，铁粉粒径越小，反应速率越快；在反应速率达到峰值后，铁粉粒径越小，反应速率越慢；在转化率大于0.300时，对于30、40、55及120 μm的铁粉，粒径越小，活化能越小。研究成果基于氧浓度、粒径大小、加热速率多变量取得，研究了微米级铁粉的中低温全过程氧化特性，计算了多种微米级铁粉的活化能数据，为金属燃料应用提供理论基础，为建立铁粉燃烧反应动力学机理提供实验参数，为金属燃烧仿真实验提供理论参考，为金属燃料应用提供基础。

关键词: 热重分析, 微米级铁粉, 氧化, 热力学过程, 再生能源, 活化能