Experimental study on the effect of coal thickness and breakdown voltage on energy conversion during electrical disintegration

The high-voltage electrical pulse coal fracturing technology based on the principle of electrical disintegration (ED) has been put forward, but the voltage and current waveform are rarely reported. In this study, effects of coal thickness and breakdown voltage on voltage and current waveforms in during ED in air environment were investigated. Besides, the changes of peak current, electric breakdown delay and instantaneous power with the variations of coal thickness and breakdown voltage were analyzed, and the changes of deposited energy and energy conversion rate with the variations of thickness and breakdown voltage were discussed. The results show that coal thickness and breakdown voltage have notable effects on deposited energy. Under the same breakdown voltage, the deposited energy inside coal samples with different thicknesses differs. In contrast, with the same coal thickness, the deposited energy in coal sample increases with the increase of breakdown voltage. The energy conversion rate increases first and then decreases with the increase of coal thickness, while it decreases first and then increases with the increase of voltage. Therefore, with certain coal thickness, there is an optimum breakdown voltage which enables the energy conversion efficiency to reach the optimal.