On the Mechanism of High-Voltage Pulsed Fragmentation from Electrical Breakdown Process

Zhu, Xiaohua; Luo, Yunxu; Liu, Weiji; He, Ling; Gao, Rui; Jia, Yudan

doi:10.1007/s00603-021-02537-5

Cited by 50 publications

(24 citation statements)

References 37 publications

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“…Plasma Pulse Geo Drilling (PPGD) is a novel contactless drilling technology, which uses high-voltage electric pulses to break away the rock, without relying on mechanical abrasion (e.g., [5,[8][9][10][11][12][13][14][15][16][17][18][19]). Thus, PPGD is part of a class of new "contactless" drilling technologies, which also includes thermal spallation (e.g., [6,[20][21][22][23][24][25][26][27][28][29][30][31][32]) and water jet drilling (e.g., [33][34][35][36][37]) and laser drilling (e.g., [38][39][40][41][42][43]) to name only some.…”

Section: Introductionmentioning

confidence: 99%

“…In PPGD, an electric pulse between about 200 and 500 kV is applied across a rock sample to cause the rock to fracture. Typically, when such a high voltage discharge occurs on a rock surface, the electric breakdown occurs in the fluid connecting the two electrodes (i.e., the drilling fluid), because the fluid has a higher electrical conductivity than the rock [8,10,11,16,19]. This higher electrical conductivity is caused by conductingimpurities in non-synthetic fluids (e.g., water).…”

Section: Introductionmentioning

confidence: 99%

“…Several experimental studies have investigated the mechanisms underlying the electric breakdown of solid materials and specifically the electric breakdown of rock using PPGD-type methods. These studies have observed three different mechanisms, which are the "partial discharge breakdown", the "electrical treeing breakdown", and the "thermal breakdown", which are different as we discuss briefly next [10,11,16,17,19,46,[48][49][50].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Numerically, Zhu et al [19] used the dielectric breakdown condition to investigate whether the partial discharge occurs at the pore scale. Zhu et al [19] assumed that the partial discharge breakdown induces local damage at the microscale without calculating the induced local stresses. In contrast, in this paper, we study the "Partial Discharge Breakdown" mechanism by modeling the plasma formation in rock pores to determine whether the resulting pore pressure is sufficient to fracture granite.…”

Section: Introductionmentioning

confidence: 99%

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Simulating Plasma Formation in Pores under Short Electric Pulses for Plasma Pulse Geo Drilling (PPGD)

et al. 2021

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Plasma Pulse Geo Drilling (PPGD) is a contact-less drilling technique, where an electric discharge across a rock sample causes the rock to fracture. Experimental results have shown PPGD drilling operations are successful if certain electrode spacings, pulse voltages, and pulse rise times are given. However, the underlying physics of the electric breakdown within the rock, which cause damage in the process, are still poorly understood. This study presents a novel methodology to numerically study plasma generation for electric pulses between 200 and 500 kV in rock pores with a width between 10 and 100 μm. We further investigate whether the pressure increase, induced by the plasma generation, is sufficient to cause rock fracturing, which is indicative of the onset of drilling success. We find that rock fracturing occurs in simulations with a 100 μm pore size and an imposed pulse voltage of approximately 400 kV. Furthermore, pulses with voltages lower than 400 kV induce damage near the electrodes, which expands from pulse to pulse, and eventually, rock fracturing occurs. Additionally, we find that the likelihood for fracturing increases with increasing pore voltage drop, which increases with pore size, electric pulse voltage, and rock effective relative permittivity while being inversely proportional to the rock porosity and pulse rise time.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Simulating Plasma Formation in Pores under Short Electric Pulses for Plasma Pulse Geo Drilling (PPGD)

et al. 2021

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Recycling of Thermoplastic Glass Fiber‐Reinforced Composites Using High‐Voltage Fragmentation

Schmidt,

Auer,

Grammel

et al. 2024

Chemie Ingenieur Technik

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A rectangular polymer profile made of glass fiber‐reinforced thermoplastic sheathing material and a polyethylene terephthalate foam core were to be separated for recycling. For this purpose, a mechanical recycling process utilizing a cutting mill and the high‐voltage fragmentation (HVF) process were used and their achievements in composite separation were compared. For both separation methods, parameter variations resulted in a total of two test series each consisting of drying, screening, optional density separation, ashing, weighing, microscopic analyses, and glass fiber length measurements. Using HVF, a better separation of the core and sheath materials was achieved and longer glass fibers could be recovered.

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The effect of magnetic field on the electric breakdown trajectory of high‐voltage electric pulse rock breaking

Liu,

Zhou,

Zhu

2023

Contributions to Plasma Physics

Self Cite

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High‐voltage electric pulse drilling technology has the advantages of high rock‐breaking efficiency, low energy consumption for rock breaking, and good quality of well wall, which is a new and efficient potential rock‐breaking method. In this paper, we constructed a numerical simulation model of rock electric breakdown and realized the whole process of rock breaking and plasma channel generation by high‐voltage electric pulse. The results of the study showed that the change of magnetic field has a large influence on the formation of plasma channels inside the rock, and under the self‐magnetic field environment, the plasma channels inside the rock show branching, and the maximum penetration depth and maximum damage depth are higher than those under the non‐magnetic field environment. In the external magnetic field environment, the plasma channels gradually tend to develop “downward” (inside the rock), and the temperature distribution of the plasma channels inside the rock is more concentrated. In the presence of a magnetic field, the speed and degree of freedom of charged particles are limited. In an external magnetic field environment, the charged particles cause fewer particles to deviate, and the particles show a “downward” accumulation phenomenon. The research in this paper can provide certain theoretical and technical guidance for the development of electric pulse rock‐breaking technology and provide reference for the development and parameter optimization of electric pulse rock‐breaking tools.

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On the Mechanism of High-Voltage Pulsed Fragmentation from Electrical Breakdown Process

Cited by 50 publications

References 37 publications

Simulating Plasma Formation in Pores under Short Electric Pulses for Plasma Pulse Geo Drilling (PPGD)

Simulating Plasma Formation in Pores under Short Electric Pulses for Plasma Pulse Geo Drilling (PPGD)

Recycling of Thermoplastic Glass Fiber‐Reinforced Composites Using High‐Voltage Fragmentation

The effect of magnetic field on the electric breakdown trajectory of high‐voltage electric pulse rock breaking

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