A Coupled Electromagnetic Irradiation, Heat and Mass Transfer Model for Microwave Heating and its Numerical Simulation on Coal


As hydraulic fracturing as a means to enhance coal bed methane was banned in some countries due to possible negative environmental impacts, the microwave heating was proposed as an alternative approach to enhance coal permeability and thus gas productivity. One of the mechanisms on improving coal permeability using microwave irradiation is that thermal stress caused by microwave heating generates fractures. To study the influence of microwave settings to the heating effect of coal samples, a coupled mathematical model for electromagnetic, heat and mass transfer in the process of microwave heating is proposed and is numerically implemented using a finite element method. This coupled model for microwave heating have considered heat and mass transfer, and is validated by comparison with experimental results. Then it is used to simulate the influence of frequency, power and moisture capacity on microwave heating. The simulation results show that microwave heating of coal is highly sensitive to excitation frequency. Frequencies around 3.45 GHz contribute to significant thermal heterogeneity. With the same energy input, different powers do not influence the overall heating effect, but higher powers cause greater thermal heterogeneity. Moisture capacity also has great effect on microwave heating and thermal distribution pattern. Under 2.45 GHz and 1.0 kW, the coal sample with moisture capacity of 5% has the best microwave heating effect.


Mining Engineering


This project is supported by the National Natural Science Foundation of China (Grant No. 51774279 ), the Petrochemical Joint Funds of National Natural Science Foundation of China and China National Petroleum Corporation (Grant No. U1762105 ), the Independent Research Projects of State Key Laboratory of Coal Resources and Safe Mining , CUMT (SKLCRSM15KF01), and the Mining Education Australia Collaborative Research Grant Scheme (2017). The research stipend support from China Scholarship Council (No. 201606430006) is acknowledged.

Keywords and Phrases

Coal; Coal bed methane; Coal deposits; Computer simulation; Environmental impact; Finite element method; Gas permeability; Irradiation; Mass transfer; Methane; Microwave irradiation; Moisture; Numerical models; Coal permeabilities; Coupled mathematical modeling; Electromagnetic irradiation; Excitation frequency; Heat and mass transfer; Heat and mass transfer models; Thermal distributions; Thermal heterogeneity; Microwave heating; Coal permeability enhancement; Numerical simulation

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Article - Journal

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© 2018 Elsevier, All rights reserved.

Publication Date

01 Aug 2018