Abstract Microwave heating is a promising technology in coal processing and coal seam permeability enhancement. It is vital to investigate the influencing factors for microwave heating of coal to ensure the optimal heating effect and the best energy efficiency. To address this, different types of coal samples with various water saturation were treated with various microwave powers and irradiation times. Thermocouple and infrared thermal image system were used to measure the temperature of coal samples during and after microwave treatment. Through analysing the temperature, the effects of dielectric property and water saturation of coal, microwave power and treatment time on microwave heating were investigated. It was found the heating rate of coal samples increases with the loss factor at the initial heating period, which then changes as the composition changes under microwave irradiation. It was also found that coal samples with low water saturation have much better microwave heating effects. Moisture not only impedes microwave heating but also facilitates uniformed heating, which impedes the formation of thermal fractures. Additionally, the experiment results suggest the average temperature increases with microwave power and irradiation time. However, extending the microwave irradiation time is more effective when the microwave power increases to a certain extent.

中文翻译：

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不同介电特性和含水饱和度煤的有效微波加热/压裂试验研究

摘要 微波加热是煤炭加工和提高煤层渗透率的一种很有前景的技术。研究煤炭微波加热的影响因素对于确保最佳的加热效果和最佳的能源效率至关重要。为了解决这个问题，用不同的微波功率和辐照时间处理具有不同含水饱和度的不同类型的煤样。采用热电偶和红外热像系统测量微波处理过程中和微波处理后的煤样温度。通过对温度的分析，考察了煤的介电特性和含水饱和度、微波功率和处理时间对微波加热的影响。发现煤样的加热速率随着初始加热期的损失因子而增加，然后在微波辐射下随着成分的变化而变化。还发现含水饱和度低的煤样具有更好的微波加热效果。水分不仅阻碍微波加热，而且有利于均匀加热，从而阻碍热断裂的形成。此外，实验结果表明平均温度随微波功率和辐照时间而增加。但是，当微波功率增加到一定程度时，延长微波照射时间更为有效。实验结果表明，平均温度随微波功率和辐照时间而增加。但是，当微波功率增加到一定程度时，延长微波照射时间更为有效。实验结果表明，平均温度随微波功率和辐照时间而增加。但是，当微波功率增加到一定程度时，延长微波照射时间更为有效。