ANALYSIS OF THE THERMAL MECHANISM AND TEMPORAL AND SPATIAL EVOLUTION OF THE THERMAL FIELD OF DEEP SANDSTONE UNDER MICROWAVES.

In the practice of the deep engineering, it is expected to improve engineering ef- ficiency by introducing the microwave energy. Therefore, based on 1050 m deep sandstone, the heating characteristics of sandstone and its constituent minerals in the microwave field are comprehensively explored through experiments and numerical simulations. In the paper, the asynchronism of the temperature rise in different areas of the sandstone depends on the local characteristics of dielectric loss and maximum heat storage capacity. With increase of the temperature, the evaporation of the water leads to the decrease of the dielectric properties, the increase in the constant-pressure heat capacity and the increase in the heat dissipation coeffi- cient, which suppresses the temperature growth trend. The temperature rise of the amplitude of the material is lower than that expected from the microwave power. The maximum temperature of dolomite, feldspar and quartz under the power of 2000 W is 1.86, 1.71, and 1.63 times that of the power of 1000 W, respectively. It is necessary to select the reasonable microwave power to maximize the engineering efficiency. The results are expected to provide the theoretical and technical supports for the electromagnetic heat generation in deep engineering. [ABSTRACT FROM AUTHOR]