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"Conveying"
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In Situ Formation of MoSsub.2 on the Surface of CF to Improve the Tribological Properties of PUE
The roller is an important part of the belt conveyor used in coal transportation. Due to the harsh environment of coal mines, the rollers are in a state of high load and high friction for a long time, which causes wear failure and has a serious impact on the reliability and safety of the equipment. In order to prepare roller material with excellent bearing performance and friction performance, CF/PUE composites were prepared by pouring method with polyurethane as the matrix and carbon fiber as reinforcement. Due to the low surface activity of unmodified carbon fibers and poor bonding performance with the matrix, MoS[sub.2] was generated on the surface of carbon fiber by the in situ generation method in this paper. It was found that the mechanical properties of MoS[sub.2]/CF/PUE composites were better when the CF content was 0.3 wt%. The Shore hardness reached 92.2 HA, which is 10% higher than pure polyurethane. The tensile strength was 38.44 MPa, which is 53% higher than pure polyurethane. The elongation at break was 850%, which is 16% higher than pure polyurethane. The maximum compressive stress was 2.32 MPa, which is 42% higher than pure polyurethane. The friction coefficient was much lower than that of pure PUE composites, the friction coefficient was 0.284, which is 59% lower than pure polyurethane.
Journal Article
Effects of model grid spacing for warm conveyor belt - Part 1: Lagrangian perspective
Warm conveyor belts (WCBs) in extratropical cyclones transport moisture and hydrometeors into the upper troposphere and lower stratosphere (UTLS), influencing the radiative balance. Earlier research has shown that the horizontal grid spacing of numerical weather prediction (NWP) models has an impact on the modelled WCB properties, such as ascent rates and diabatic heating. This first part of a two-part study examines the impact of model grid spacing on the transport of moisture from a Lagrangian perspective. We analyze two ICON model simulations of one North Atlantic WCB case study: a convection-parameterizing run at â¼ 13 km and a convection-permitting run at â¼ 3.5 km approximate grid spacing. We hypothesize that key differences in the modelled transport of moisture arise from higher vertical velocities in the high-resolution simulation. The convection-permitting simulation produces more rapid ascent and a drier WCB outflow with lower specific and relative humidity. We attribute this to higher ice number concentrations, which deplete supersaturation more efficiently. This high-resolution simulation also exhibits more pronounced frozen-phase microphysics, stronger frozen precipitation, notably different hydrometeor mass mixing ratios, number concentrations, and radii than the lower resolution simulation - indicating that horizontal resolution substantially influences modelled WCB cloud composition. These results demonstrate that weather and climate models using convection-parameterizing resolutions may systematically misrepresent WCB cloud properties and UTLS humidity, with potential consequences for accurately simulating Earth's radiative budget and upper-level flow.
Journal Article
Recent progress on dynamics and control of pipes conveying fluid
Pipeline systems are crucial in fluid-conveying pipes across diverse engineering disciplines, including aerospace, oil transportation, deep-sea exploration, and nuclear energy projects. The engineering application of fluid-conveying pipes in these fields is significantly constrained by the substantial coupling between the fluid and the pipeline, which is attributed to many factors, such as complex structural and functional design, support conditions, internal flow, and the influence of the external environment. Consequently, the complex dynamic behavior of pipes conveying fluids has garnered considerable attention from scholars in engineering and scientific domains. Given the background of engineering application, this article offers a comprehensive and in-depth analysis and discourse on the most recent research and advancements in the field of vibration and control of fluid-conveying pipes, which includes straight and curved fluid-conveying pipes, fluid-conveying pipes with different geometric configurations, fluid-conveying pipes with complex support and constraints, fluid-conveying pipes with extensive motion superposition, fluid-conveying pipes affected by internal and external flows, multiphase fluid-conveying pipes, fluid-conveying pipes made of composite materials, and passive and active control for fluid-conveying pipes. Here we presented some specific examples of the pipelines applied in practical engineering and explored the role of emerging technology, such as machine learning on dynamics and control. This comprehensive analysis will provide with a deep understanding of the subject matter.
Journal Article
Microwave-Only Heating Concepts for Industrial COsub.2 Regeneration System Design
This study presents various microwave reactor designs specifically engineered for continuous microwave CO[sub.2] desorption, marking a significant advancement in microwave-heating systems. This study explored both horizontal and vertical continuous microwave reactor configurations. The horizontal design incorporates a modified conveyor belt system with cleated belts and Teflon sidewalls, rendering it particularly suitable for the regeneration of gas. Conversely, the vertical design utilizes a cascade gate opening mechanism, facilitating precise control over the microwave intensity and exposure duration. The efficiency of microwave power utilization was enhanced through the numerical modeling and optimization of the reactor dimensions. This study assessed the impact of waveguide placement, cavity size, and sorbent material thickness on power absorption and heating. The findings indicate that strategic waveguide positioning and optimal cavity dimensions significantly influence the microwave energy distribution and absorption, leading to reduced hotspots and more uniform heating. This study offers valuable insights into the design and optimization of microwave reactors for CO[sub.2] desorption, contributing to more efficient and effective commercial applications of this technology. These results underscore the potential of microwave technology to revolutionize desorption processes and pave the way for further advancements in this domain. Design 2 exhibited more uniform heating owing to its slower and controlled temperature increase, making it more suitable for applications requiring consistent thermal performance over extended periods.
Journal Article
An Experimental Study on the Elbow Pressure Drop and Conveying Stability of Pneumatic Conveying for Stiff Shotcrete Based on Response Surface Methodology
The pressure drop and conveying stability caused by the bend significantly affect the pneumatic conveying process of stiff shotcrete, which is the key to solving the problem of long-distance transportation. In this paper, the effects of different air velocities (32 m/s, 36 m/s, 40 m/s), water-cement ratios (0.1, 0.2, and 0.3), and bending-diameter ratios (4, 12, and 20) on the pressure drop of the elbow R1 and conveying stability R2 are studied using the response surface method. The conveying stability is characterized by the pressure variation coefficient (C.V). The response surface graph aids in the intuitive analysis of the effects of these variables. The results show that the impact of air velocity on R1 and R2 is exceptionally significant, and the interaction of each factor on the response value is analyzed. The response value and the quadratic polynomial regression equation between the various factors are obtained in addition to the flow characteristics of stiff shotcrete under different working conditions. The relationship established by the statistical processing of the experimental results can provide some reference for specifying the pressure loss model of stiff shotcrete.
Journal Article
Vibration control of fluid-conveying pipes: a state-of-the-art review
Fluid-conveying pipes are widely used to transfer bulk fluids from one point to another in many engineering applications. They are subject to various excitations from the conveying fluids, the supporting structures, and the working environment, and thus are prone to vibrations such as flow-induced vibrations and acoustic-induced vibrations. Vibrations can generate variable dynamic stress and large deformation on fluid-conveying pipes, leading to vibration-induced fatigue and damage on the pipes, or even leading to failure of the entire piping system and catastrophic accidents. Therefore, the vibration control of fluid-conveying pipes is essential to ensure the integrity and safety of pipeline systems, and has attracted considerable attention from both researchers and engineers. The present paper aims to provide an extensive review of the state-of-the-art research on the vibration control of fluid-conveying pipes. The vibration analysis of fluid-conveying pipes is briefly discussed to show some key issues involved in the vibration analysis. Then, the research progress on the vibration control of fluid-conveying pipes is reviewed from four aspects in terms of passive control, active vibration control, semi-active vibration control, and structural optimization design for vibration reduction. Furthermore, the main results of existing research on the vibration control of fluid-conveying pipes are summarized, and future promising research directions are recommended to address the current research gaps. This paper contributes to the understanding of vibration control of fluid-conveying pipes, and will help the research work on the vibration control of fluid-conveying pipes attract more attention.
Journal Article
The Influence of Wind Speed on Pneumatic Conveying Characteristics of Solid Feed in Horizontal Pipe by Simulation and Experiment
Pneumatic conveying technology is an efficient, energy-saving and environmentally friendly means of solid feed conveying. In the process of pneumatic conveying, wind speed has a decisive influence on conveying characteristics. Here, computational fluid dynamics coupled with a discrete element method simulation and experiment were combined, and the conveying wind speed was used as the experimental variable to study the conveying characteristics of the conveying material in the tube, such as particle distribution state, solid phase mass concentration, coupling force on solid feed, average speed and pressure drop of solid feed in the pipe. The results show that when the conveying wind speed increases from 18 m/s to 20.6 m/s, the solid feed changes from sedimentary flow to suspended flow, the particle accumulation gradually decreases and the conveying efficiency is significantly improved. The particle slug greatly reduces the collision and friction between the internal particles and the pipe and reduces the crushing rate to a certain extent. When the conveying wind speed is about 23.2 m/s, there are almost no trapped particles in the pipeline, which can achieve rapid feed delivery, and conveying efficiency is greatly improved. Therefore, this paper provides a good theoretical basis for improving conveying efficiency and reducing crushing rate in the process of pneumatic conveying.
Journal Article