Experimental Study On The Dielectric Constant Of Tectonic Coal

In order to study on the influence factors on the dielectric constant of tectonic coal, design and make a test system of electrical parameters of coal samples, which can be able to conduct different frequency measuring for electrical parameters of coal samples under circumstances of different temperature, water content and test frequency. It is found that: 1 the dielectric constant of the anthracite increases as the temperature increases under the temperatures of 20 similar to 120 degrees C in Lab, while that of tectonic coal of other metamorphic grade slightly decreases with the temperature increasing; 2 with the soaking time increasing, the dielectric constants of all the rank coal samples measured tremendously increase, especially for gas-fat coal; 3 the higher the test frequency, the lower the value of dielectric constants tested; 4 there is a maximum value corresponding to the cracking stress of coal samples for dielectric constant in all the dielectric constant strain curves and the dielectric constant strain curves of the tectonic coal are better fitting to the corresponding stress strain curves, which is independent on the metamorphic grade of coal. It can be concluded that the temperature and test frequency have little effect on the dielectric constants of meager lean coal and gas-fat coal in the testing range in this paper and moisture content and stress are the main influencing factors on the dielectric constant of meager lean coal and gas-fat coal.