Numerical simulation study on the coupling mechanism of composite-source airflow–dust field in a fully mechanized caving face

Advances in Civil Engineering

et al. 2019

Polyethylene terephthalate (PET) fiber from waste plastic bottles is an environmentally friendly fiber that can improve the mechanical properties of wet-mix shotcrete. The main objective of this paper is to investigate the effects of PET fiber parameters on pumpability, shootability, and mechanical properties of wet-mix shotcrete. For this purpose, the orthogonal test based on three factors and three levels was conducted. The width, length, and content of PET fiber were selected as the experimental variables. The tests of wet-mix shotcrete reinforced by PET fibers were carried out, along with properties tests such as slump, pressure drop, build-up thickness, compressive strength, and splitting strength. The results showed the change trend of shotcrete performances with increasing PET fiber parameters (width, length, and content). According to the orthogonal test, PET fiber parameters were determined (1 mm width, 20 mm length, and 5 kg/m3 content). Furthermore, relationships between slump and pumpability and shootability were explored, as well as the relationships between pumpability, shootability, and mechanical properties. It was found that pressure drop and compressive strength had the strongest negative linear relationship among all fitting relationships. We hoped that this study could contribute the useful information for the application of wet-mix shotcrete mixed with PET fibers.

Section: Introductionmentioning

confidence: 99%

Effects of PET Fibers on Pumpability, Shootability, and Mechanical Properties of Wet‐Mix Shotcrete

Cui

Liu

Advances in Civil Engineering

et al. 2019

“…Currently, the main dust prevention methods in underground coal mine include preinjection of water into coal, ventilation, exhausting of dust, purification of air by dust remover, spraying, and dust isolation via enclosing [19][20][21][22][23][24][25]. Spraying has been extensively applied in underground mines for dedusting due to the low cost, convenient operation, and practicability [26][27][28][29][30][31]. e results in previous studies also revealed that the dust-suppression efficiency via spraying was closely related to the wettability of the coal dust.…”

Section: Introductionmentioning

confidence: 97%

Effects of Metamorphic Degree of Coal on Coal Dust Wettability and Dust‐Suppression Efficiency via Spraying

Advances in Materials Science and Engineering

Han

Liu

et al. 2020

Currently, spraying is a main means for dust prevention and control in underground coal mines. The dust-suppression efficiency via spraying is highly correlated with the wettability of coal dusts. There are many factors affecting the wettability of coal dust, among which coal’s metamorphic degree has great influence. In order to gain in-depth knowledge of the effects of coal metamorphic degree on coal dust wettability and the dust-suppression efficiency via spraying, 6 coal dust samples with different metamorphic degrees were collected and used in the study. In the experiments, the microproperties, wetting performance, and dust-suppression efficiency via spraying were measured. According to the experimental results of coal’s microproperties, with the improvement of metamorphic degree, the content of hydrophilic oxygen-containing functional groups on the surface, the surface roughness, the specific surface area, and the interpore diameter all decreased. In addition, as coal’s metamorphic degree was enhanced from lignite to meager-lean coal, the wettability of the coal dust dropped. On the other hand, as the metamorphic degree of coal quality continued to be improved to anthracite, the wettability of the coal dust increased instead. The measured results revealed that the dust-suppression efficiency via spraying was highly correlated with the wettability of coal dust. The coal dust with better wettability exhibited higher dust-suppression efficiency via spraying. With the increase of water-supply pressure, the effect of coal dust wettability on the dust-suppression efficiency via spraying was weakened, and the difference of dust-suppression efficiency among different coal dust samples was narrowed.

“…According to the regulation from the National Health Committee of China, at production sites, the 8-hour weighted average concentrations of total dust and respirable dust should be lower than 4.0 mg/m 3 and 2.5 mg/m 3 , respectively. Meeting this regulation is a challenge for most production companies (Han et al, 2020b;Liu et al, 2020;Wang et al, 2019a;Xiu et al, 2019;Cheng et al, 2016). Nowadays, various production enterprises have adopted a large number of effective dust protection measures; however, the situation of occupational disease in China is still severe, and pneumoconiosis is still the most serious occupational disease in China.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Model of SMD of Hydrodynamic Ultrasonic Atomizing Nozzle Based on Orthogonal Design

Tian

et al. 2021

Preprint

The hydrodynamic ultrasonic atomization nozzle has excellent atomization performance and has a wide range of applications in the field of spray dust reduction. A mathematical model the SMD of the nozzle was established to evaluate the SMD of such nozzles using the custom-designed spraying experiment platform and orthogonal design methods. The interaction between the SMD of the nozzle and the three influencing factors, i.e., air pressure, water pressure and outlet diameter were obtained. Through range analysis, the primary and secondary order of the three parameters affecting SMD of the nozzle is: air pressure > water pressure > outlet diameter. On this basis, a mathematical model was constructed using a multivariate nonlinear regression method to estimate the SMD of the nozzle. The predicted values of the SMD of the nozzle by the multivariate nonlinear regression mathematical model were basically consistent with the experimental results, with an average relative error of only about 5%. Thus the established mathematical model in this paper can be used to predict and calculate the droplet size for hydrodynamic ultrasonic atomizing nozzles.