Two-Group Drift-Flux Model for Dispersed Gas-Liquid Flow in Large-Diameter Pipes

Interfacial Heat and Mass Transfer Are Prevalent in Industrial Processes. the Interfacial Transfer Rate Can Be Obtained by the Product of their Fluxes and Interfacial Area Concentration (IAC) Calculated by the Interfacial Area Transport Equation (IATE). Bubbles Show Different Behavior According to their Sizes. Hence, Bubbles Are Classified into Two Groups. Consequently, Two-Group IATE is Required Causing to Use of Two Gas Momentum Equations Leading to More Complexity. the Present Study Suggests a New Reliable Two-Group Drift-Flux Modeling to Reduce the Two Gas Momentum Equations to One Gas Mixture Momentum Equation for Gas-Liquid Flow in Large-Diameter Pipes. the Model is Developed based on the Drift-Flux Model Concept and Experimental Data. Group-One and Group-Two Distribution Parameters and Drift Velocities Are Validated through Experimental Data. the Results Show that the Proposed Two-Group Drift-Flux Model Can Support the Concept of Drift Velocity from the Bubbly to Beyond the Bubbly Flow and Consistency between the One-Group and Two-Group Drift-Flux Models. Moreover, Steam-Water Data Are Used to Validate the Applicability of the Model in Steam-Water Flows Condition. the Developed Two-Group Drift-Flux Model is Indispensable for Reducing the Two Gas Momentum Equations to One Gas Mixture Momentum Equation When Two-Group IATE is Implemented into Thermal-Hydraulic Codes to Improve the Prediction Accuracy of IAC

A Vehicle-bridge Interaction Model Considering Contact Patch Size And Vehicle Self-generated Excitation – A Theoretical Study

This paper presents an improved theoretical damped single-axle vehicle-bridge dynamic interaction model to consider the effect of the contact patch size and motor-induced vehicle excitation. The contact patch issue is critical as it determines the minimum time step for simulation and maximum identifiable frequency, while the inclusion of the motor-induced vehicle excitation benefits the design of autonomous self-driven rather than towed vehicles. Estimations of the contact patch size for both the pneumatic tire and solid wheel scenarios are discussed. The contact patch responses, which degenerate into contact point responses when the contact patch size is assumed to be infinitely small, were derived for the first time both from the vehicle and bridge responses to confirm their equivalence. The minimum time step, which determines maximum identifiable frequency but is arbitrarily chosen in literature, is proposed to be determined by the vehicle speed and contact patch length. The procedures to extract multiple bridge triad information including natural frequencies, mode shapes, and damping ratios from the vehicle responses are also presented. Based on extensive parametric analyses, the sinusoidal vehicle excitation becomes more prominent as its amplitude and/or frequency increase and may overshadow the analysis of bridge frequencies of interest. The vehicle acceleration leads to a more accurate extraction of bridge mode shapes and damping ratios than the vehicle displacement since the displacement is dominated by the fundamental mode of bridge vibration. The damping ratio extraction shows an average error of 0.28% from the instantaneous amplitude of the vehicle acceleration signal

Optimal Power Flow Using A Hybridization Algorithm Of Arithmetic Optimization And Aquila Optimizer

In this paper, a hybridization method based on Arithmetic optimization algorithm (AOA) and Aquila optimizer (AO) solver namely, the AO-AOA is applied to solve the Optimal Power Flow (OPF) problem to independently optimize generation fuel cost, power loss, emission, voltage deviation, and L index. The proposed AO-AOA algorithm follows two strategies to find a better optimal solution. The first strategy is to introduce an energy parameter (E) to balance the transition between the individuals\u27 procedure of exploration and exploitation in AO-AOA swarms. Next, a piecewise linear map is employed to reduce the energy parameter\u27s (E) randomness. To evaluate the performance of the proposed AO-AOA algorithm, it is tested on two well-known power systems i.e., IEEE 30-bus test network, and IEEE 118-bus test system. Moreover, to validate the effectiveness of the proposed (AO-AOA), it is compared with a famous optimization technique as a competitor i.e., Teaching-learning-based optimization (TLBO), and recently published works on solving OPF problems. Furthermore, a robustness analysis was executed to determine the reliability of the AO-AOA solver. The obtained result confirms that not only the AO-AOA is efficient in optimization with significant convergence speed, but also denotes the dominance and potential of the AO-AOA in comparison with other works

Introduction

For more than a century, concrete research has focused on improving the mechanical properties and durability of concrete, focusing on the effects of mix design parameters and exposure conditions on the responses to different mechanical, physical and chemical solicitations

Empirical Test Methods To Evaluate Rheological Properties Of Concrete And Mortar

Several empirical test methods used to measure the workability of cement-based materials under field conditions can be employed to evaluate the fundamental rheological properties of these materials. This chapter summarized some of the analytical solutions of different workability test methods for concrete and mortar from the rheological basis. Many of the relationships between the various workability parameters of concrete and mortar determined using empirical tests and their corresponding rheological properties, namely yield stress, plastic viscosity, and thixotropy are evaluated. Limitations of the applicability of the various empirical methods are highlighted to avoid erroneous estimates of rheological characteristics. Established relations between flow properties of 3D printing mortar measured by empirical squeeze and penetration tests and the rheological characteristics are also presented. Other test methods for monitoring the output of concrete mixing trucks, including the imposed load and hydraulic pressure, and the correlations between the rheological performance are discussed for the application of in-drum measurement systems

Challenges Encountered During Measuring Rheological Properties Of Mortar And Concrete

Performing rheological measurements of mortar and concrete is not a straightforward task as many challenges can alter or invalidate the outcome of a rheological experiment. This chapter summarizes the most common challenges for flow curve measurements, which are the type of flow behavior, achieving the reference state, plug flow, shear and gravity-induced particle migration, hydrodynamic pressure, heat of vaporization, correct choice of rheological transformation equations and model, air, and wall effects. Some of these challenges are also detailed separately for static yield stress measurements. For each challenge, the physical background, consequence on the measurement outcome and any detection or prevention strategy are described. To adequately perform rheological measurements, all challenges need to be addressed, which can be a daunting task as some prevention strategies can increase the risk for a different challenge to affect the measurement. Developing a suitable measuring and analysis procedure is a critical task to the success of rheological measurements of mortar and concrete

Metal-Organic Frameworks-Membranes for Energy Intensive Liquid Separation

Metal-Organic Frameworks (MOFs) Materials with Tunable Structures and Functionalities Have Demonstrated Great Potential as Promising Membrane Materials,and Play a Crucial Role in Various Industrially Important Chemical, Energy, and Environmental Processes. Due to their Well-Defined Pore Systems, Unique Chemicalversatility, and Abundant Chemical Functionalities, MOFs Have Garnered Interest for Various Energy Intensive Separation Applications. Formulating Them into Structured Configurations is a Key Step toward their Scale Up and Successful Implementation at the Industrial Level. This Review Focuses on the Latest Development on MOF-Based Membranes for Liquid Separations and Highlights Recent Progress on Design Strategies, Criteria for Screening MOFs, Fabrication Methods, the Most Recent Breakthrough in the Areas of Pervaporation, Water Treatment, and Organic Solvent Nanofiltration. Additionally, This Study Also Discusses the Possible Applications of MOF-Based Membranes in the Removal of Micropollutants, in Decay Processes and Exhibiting Antibiotic Properties. the Remaining Challenges, Prospects and Guidance on the Rational Design and Fabrication of High-Performance MOF-Based Membranes and Transferring Technology from Laboratory Scale towards Practical Applications Are Discussed

Revisiting The Divergent Multipole Expansion Of Atom-surface Interactions: Hydrogen And Positronium, Α -quartz, And Physisorption

We revisit the derivation of multipole contributions to the atom-wall interaction previously presented in Łach et al. [G. Łach, M. DeKieviet, and U. D. Jentschura, Phys. Rev. A 81, 052507 (2010)10.1103/PhysRevA.81.052507]. A careful reconsideration of the angular momentum decomposition of the second-, third-, and fourth-rank tensors composed of the derivatives of the electric-field modes leads to a modification for the results for the quadrupole, octupole, and hexadecupole contributions to the atom-wall interaction. Asymptotic results are given for the asymptotic long-range forms of the multipole terms, in both the short-range and long-range limits. Calculations are carried out for hydrogen and positronium in contact with α-quartz; a reanalysis of analytic models of the dielectric function of α-quartz is performed. Analytic results are provided for the multipole polarizabilities of hydrogen and positronium. The quadrupole correction is shown to be numerically significant for atom-surface interactions. The expansion into multipoles is shown to constitute a divergent, asymptotic series. Connections to van der Waals corrected density-functional theory and applications to physisorption are described

Sustainable Pathways For Solar Desalination Using Nanofluids: A Critical Review

Water is a fundamental requirement for the survival of human beings. Although water is abundantly available across the globe, access to freshwater still remains a major concern. Most of the water available is saline or brackish, which is not fit for human consumption. Desalination is the optimum solution for production of potable water from saline water. A major shortcoming of conventional desalination technologies is their dependence on fossil fuel that results in environmental degradation, global warming, etc. Therefore, sustainable desalination technology has evolved as a need of hour. Among all renewable energy resources, solar energy is abundantly available and can be potentially harvested. Therefore, solar energy can be used to drive sustainable desalination technologies. A solar still converts saline water into freshwater in a single step using solar energy. But the major drawbacks of solar still are relatively lower efficiency and lower yield. Nanofluids are widely used to overcome these limitations due to their extraordinary and unique properties. This paper critically reviews the recent research performed on the application of nanofluids in solar desalination systems. Methods of nanofluid preparation, their types and properties are also discussed in detail. Application of nanofluids in solar desalination systems is discussed with special attention on performance enhancement of solar stills. Combinations of nanofluids with various other performance enhancement techniques are also considered. The effectiveness of nanofluids in solar stills is found to be dependent majorly on the nature and concentration of the nanofluid used

A Review Of Dielectric Barrier Discharge Cold Atmospheric Plasma For Surface Sterilization And Decontamination

Numerous investigations have shown that non-equilibrium discharges at atmospheric pressure, also known as cold atmospheric plasma (CAP) are efficient to remove biological contaminants from surfaces of a variety of materials. Recently, CAP has quickly advanced as a technique for microbial cleaning, wound healing, and cancer therapy due to the chemical and biologically active radicals it produces, known collectively as reactive oxygen and nitrogen species (RONS). This article reviews studies pertaining to one of the atmospheric plasma sources known as Dielectric Barrier Discharge (DBD) which has been widely used to treat materials with microbes for sterilization, disinfection, and decontamination purposes. To advance research in cold atmospheric plasma applications, this review discusses various types and configurations of barrier discharge, the role played by reactive species and other DBD-CAP agents leading to its antimicrobial efficacy, a few collection of DBD-CAP past studies specifically on surface, and emerging applications of DBD-CAP technology. Our review showed that non-thermal/equilibrium plasma generated from DBD could sterilize or disinfect surface of materials without causing any thermal damage or environmental contamination