Tube Shape Research Articles

A Review on Heat Transfer Enhancement in a Heat Exchanger

Compact heat exchanger is commonly used in car radiators which is normally small with low flowrate. To produce a large surface area, thin plates or corrugated fins are attached closely separating the two fluids. Compact heat exchanger is normally used in applications where weight and volume are the significant factors for the enhancement of heat transfer. This paper reviews the research related to the characteristics, advantages and findings on various type of compact heat exchanger. It is found that the geometric parameters such as fin shape, tube shape, fin pitch, tube pitch, tube arrangement, tube angle and vortex generators affect the heat transfer performance in general. The air inlet angle of 45° and common flow upstream gives the optimum heat enhancement in most studies while the most suitable air flow is between 1.8 – 3.8 m/s.

Fullerenes in dentistry: A review on unlocking their therapeutic potential in oral medicine

Fullerenes are a family of carbon allotropes that have demonstrated great potential in oral medicine. They have a distinct cage-like structure and take the shape of hollow spheres, ellipsoids, or tubes with special structural and physicochemical features. When fullerenes are spherical, they are known as buckyballs, and when they are cylindrical, they are known as carbon nanotubes or buckytubes. Due of their flexible construction, they can be used in a variety of settings, including medication delivery, gene therapy, diagnostics, and oral illness treatment. Fullerenes have the ability to conjugate or encapsulate medicinal substances, allowing for the regulated and targeted administration of drugs to tissues afflicted by diseases including mouth cancer and periodontal disease. When treating infections and long-term inflammatory disorders in the oral cavity, their capacity to improve drug stability and bioavailability is very advantageous. Functionalized fullerenes improve biosensing platforms and imaging methods in diagnostics, facilitating the early detection of illnesses and oral malignancies. There are still obstacles to overcome in order to maximize their biocompatibility, toxicity profiles, and delivery methods for clinical application, despite their enormous potential. This review aims in revolutionizing the detection and treatment of numerous oral disorders, and ongoing research endeavours to fully investigate the therapeutic potential of fullerenes in oral healthcare.

Tough Cortical Bone-Inspired Tubular Architected Cement-Based Material with Disorder.

Cortical bone is a tough biological material composed of tube-like osteons embedded in the organic matrix surrounded by weak interfaces known as cement lines. The cement lines provide a microstructurally preferable crack path, hence triggering in-plane crack deflection around osteons due to cement line-crack interaction. Inspired by this toughening mechanism and facilitated by a hybrid (3D-printing/casting) process, the study engineers architected tubular cement-based materials with the stepwise cracking toughening mechanism, that enables a non-brittle fracture. Using experimental and theoretical approaches, the study demonstrates the competition between tube size and shape on stress intensity factor from which engineering stepwise cracking can emerge. Two competing mechanisms, both positively and negatively affected by the growing tube size, arise to significantly enhance the overall fracture toughness by up to 5.6-fold compared to the monolithic brittle counterpart without sacrificing the specific strength. This is enabled by crack-tube interaction and engineering the tube size, shape, and orientation, which promotes rising resistance-curves (R-curve). "Disorder" curves and statistical mechanics parameters are proposed for the first time to quantitatively characterize the degree of disorder for describing the representation of the architected arrangement of materials in lieu of otherwise inadequate "periodicity" classification and misperceiveddisorder parameters (perturbation and Voronoi tessellation methods).

Study on seismic performance of RC columns strengthened with CFRP-steel tube self-compacting concrete

In order to study the seismic performance of Reinforced Concrete columns strengthened with Carbon Fiber Reinforced Polymer-steel tube self-compacting concrete, seven strengthened columns and one unstrengthened column were designed and manufactured with the main parameters of axial compression ratio, self-compact concrete strength, steel tube shape and steel tube thickness. The hysteresis curve, skeleton curve, ductility, energy dissipation capacity, stiffness, steel tube surface and steel bar strain variation of the specimens were analyzed. The test results show that the strengthened part of the specimen has good cooperative working ability with the RC column, and the failure process and failure mode of the specimen are similar to those of the concrete filled steel tube. Under the action of horizontal reciprocating load, the concrete at the bottom of the strengthened column is cracked; with the increase of horizontal displacement, the hysteresis curve becomes full and the energy dissipation capacity increases. The finite element software ABAQUS is used to model and analyze the specimens. The simulation results are in good agreement with the experimental results. It is proved that the simulation is reasonable and effective in unit selection, contact setting, meshing and material constitutive selection. The hysteresis curve, skeleton curve and failure mode of each specimen are obtained.

Self-growing bionic leaf-vein fins for high-power-density and high-efficiency latent heat thermal energy storage

Latent heat storage (LHS) has found extensive applications across various fields. However, large-scale deployment is still restricted due to the worse thermal charging performance of traditional LHS systems. In this research, the self-growing fins of the tube-shell LHS system are designed via the bionic topology optimized method to improve thermal storage performances, inspired by the structures and functions of leaf veins. Notably, the system installed with topology-optimized self-growing fins (T-FIN) demonstrates the shortest melting time, largest specific power density (SPD), and highest efficiency simultaneously. At the inlet conditions of 0.5 L min−1 and 358.15 K, the thermal charging time decreases by 46.4 % and 57.1 % compared with the systems equipped with traditional long-fins (L-FIN) and short-fins (S-FIN), while increasing the SPD by 80.6 % and 125.7 %, respectively. Moreover, the efficiency of exergy and entransy storage is 2.49 and 2.42 times, respectively, as large as those of the S-FIN. The intrinsic mechanism is attributed to enhanced synergy between the liquid-PCM temperature field and the flow field. Furthermore, outer tube shapes are optimized by the Genetic Algorithm for the first time, leading to a further decrease in charging time by 21.57 % compared with its original counterpart. These findings provide a valuable idea for designing efficient bionic LHS systems.

The Application of the Particle Element Method in Tubular Propellant Charge Structure: Lumped Element Method and Multiple-Element Method

Due to the orderly arrangement of tubular propellant, the permeability of combustion gases is improved, which is beneficial for enhancing the safety of the combustion system. However, current internal ballistic gas-solid flow calculation methods adopt a quasi-fluid assumption, which cannot accurately account for the characteristics of long tube shapes. Additionally, tubular propellants exhibit both overall movement and parameter distribution characteristics, necessitating the decoupling of gas and solid phases. These two deficiencies in previous studies have limited the effectiveness of gas-solid flow simulations for tubular propellant. This paper proposes a numerical calculation model suitable for tubular propellant charging based on the particle element method for internal ballistic two-phase flow. Firstly, considering the overall movement characteristics of tubular propellants, the concept of blank particle elements is introduced to represent pure gas phase regions. Then, based on computational requirements, the tubular propellants are divided to form the lumped element method and the multiple-element method. The moving boundary method is used to calculate the movement process of the propellant bed particle group and is compared with experimental results to verify the applicability of the two methods in tubular propellant beds. Analysis results show that the particle element method can effectively capture changes in the flow field inside the chamber and the position of tubular propellants. The lumped element method can quickly obtain the flow field distribution characteristics inside the chamber, while the multiple-element method can capture parameter distribution characteristics at different positions of the tubular propellants while ensuring overall movement.

Comparative analysis of entropy generation in smooth and micro-fin tubes using R513A refrigerant: A parametric study

Currently, although significant advancements have been made in understanding heat transfer coefficients and pressure decreases in different tube shapes, there is still a noticeable lack of detailed studies on the generation of entropy under flow boiling conditions. In this work, the entropy generation in micro-fin tubes (MFT1 and MFT2) and smooth tubes (ST1 and ST2) in flow boiling conditions experimentally investigated with refrigerant R513A. Research focused on evaluating influence of different input parameters on entropy generation, specifically contribution of heat transfer coefficient (HTC) and total pressure drop (TPD) on entropy generation for all testing tubes. As at a heat flux of 6 kW·m−² and a saturation temperature of 12 °C, MFT1 shows HTC contributions to entropy generation ranging from 0.032 to 0.156 W·K−1, while MFT2 ranges from 0.03 to 0.14 W·K−1. TPD contributions for both MFT1 and MFT2 range from 0.001 to 0.04 W·K−1. Hence, MFT2 shows better results than MFT1 as low entropy generation required for a good heat exchanger. Among input parameters, heat flux displays the highest sensitivity, indicating its significant influence on total entropy generation variations, while vapor quality, mass flux, and saturation temperature also demonstrate notable sensitivity. This research helps us design systems that transfer heat more effectively while using less energy. Understanding these factors can lead to more efficient heat exchangers and other thermal systems.

Falling film hydrodynamics of horizontal elliptical tube under column flow

Flow characteristics of falling film around a horizontal elliptical tube under column flow were numerically investigated with the volume of fluid method. The three-dimensional film thickness distributions for elliptical tubes with three ellipticities and two arrangements (the major axis oriented vertically and the major axis oriented horizontally) were captured. This investigation also considered the effects of spray Reynolds number and contact angle on film thickness distribution. A comparison between elliptical tube and circular tube was also performed under typical spray Reynolds number of 258 and tube spacing of 20 mm. The results show that the tube shape has a great influence on the film thickness and flow behaviors: The liquid film formed outside the elliptical tube with the major axis oriented vertically is thinner and more uniform than that of the circular tube. Conversely, the film on the elliptical tube with the major axis oriented horizontally is thicker and more non-uniform than that of the circular tube. The increasing of Reynolds number generally increases film thickness, particularly in the crest region. Under incompletely wetted condition, the increasing of ellipticity decreases the liquid film coverage rate around the tube. In addition, a correlation for predicting the film thickness around elliptical tubes was proposed.

Research on AZ31 magnesium alloy tee joint tube with lateral hole by hot extrusion forming with sand mandrel limited by stainless steel gasket

As one of the lightest metals in the world, magnesium alloy can be used to reduce weight and save energy. Magnesium alloy tubes with different shapes can also further direct the transportation of fluid in this light weight. But the tee joint tube is difficult formed because of the complex shapes. In this paper, magnesium alloy tube is applied to form tee joint tube with sand mandrel. During the deformation, the magnesium alloy tube is driven by the sand mandrel pressed by the push. Different from traditional extruding with full tubes without hole on the sidewall, some tube with holes on the sidewalls are also used in the extrusion. All the key parameters such as extrusion depth, temperature, tube length, hole size, and hole location are discussed in both simulations and experiments. After the extrusion results are obtained, the microhardness and microstructures are observed to explain the promotion of the mechanical properties. Based on the results received from both simulations and experiments, deeper extrusion depth, higher temperature, shorter length of tube, larger size of the hole, and the higher location of the hole influence positively on forming results. No matter there are holes or not on the sidewalls, the errors between the results in simulation and experiment are small. Also the simulation and experiment results can be used to investigate the shape of tee joint tubes. The surface quality can be also measured to prove the surfaces in extrusion with sand mandrel acceptable. A novel strategy to sand mandrel extrusion of magnesium alloy tee joint tube by tube with holes on sidewall is provided.

Design of Pitot-Static Tube Shapes and Their Influence on Airspeed Measurement Accuracy

Design of Pitot-Static Tube Shapes and Their Influence on Airspeed Measurement Accuracy

Multi-objective optimization and thermodynamic assessment of a solar unit with a novel tube shape equipped with a helical tape

The performance of several heat transfer mechanisms, including solar energy sources, is being improved through optimization, which also effectively supports the most efficient feasible design. A numerical study has been done on a turbulator-enhanced flat plate solar collector (FPSC) while also introducing the utilization of a quad-lobed tube as a pioneering innovation in the system’s design. The incorporation of nanoparticles into the working fluid was implemented to enhance performance, with aluminum oxide particles selected for this purpose. Furthermore, assessing the second law and analyzing exergy generation was employed to discern irreversibility within the system. Optimization of both geometric and non-geometric elements has been accomplished through the integration of a multi-objective optimization (MOO) method with machine learning (ML). Random Forest (RF), LASSO Regression (LaR), and Support Vector Regression (SVR) are the machine learning models that were utilized in order to ascertain the correlations that exist between the system’s inputs and outputs. According to the findings, RF was found to be the most appropriate algorithm for capturing the impacts of parameter variations. This was demonstrated by the high coefficient of determination (R2) quantities that RF possessed, which were 0.95, 0.99, and 0.99 for friction factor (f), exergy loss (Xd), and second law effectiveness (ηII), respectively. However, the SVR and LaR algorithms showed significant deviations from the FPSC simulation results. The SVR algorithm achieved R2 values of 0.54 for f, 0.78 for Xd, and 0.84 for ηII, while the LaR algorithm achieved R2 values of 0.65 for f, 0.99 for Xd, and 0.98 for ηII. This research aims to find the optimal input parameters that minimize f and Xd while maximizing ηII. Therefore, to determine the Pareto optimal solutions the non-dominated sorting genetic algorithm (NSGA-II) has been utilized. The result was an illustration of the Pareto set, which stands for a collection of optimal solutions. Every solution in this collection achieved the desiredbalance, obtaining the best outcomes without compromising any objectives.

How Switchbacks Can Maintain a Longer Time in the Interplanetary Space

Parker Solar Probe, the closest spacecraft to the Sun, has renewed our understanding of the solar corona and the interplanetary space. One of its important findings is the prevalence of switchbacks, which display localized magnetic reversals along the otherwise Parker spirals. While some switchbacks might disappear quickly, others can maintain for a long period of time, and there are indications that many switchbacks strengthen from the solar corona to the interplanetary space despite their magnetic tension force, which tends to straighten the magnetic field lines. Therefore, how these switchbacks could be maintained for a long period of time remains a mystery. In this paper, we employed a 3D data-driven global full magnetohydrodynamics numerical model to explore the evolution of switchbacks formed in the dynamic corona. Our simulations indicate that two factors can affect the lifetime of a switchback. One factor is the combination of angle and leg length ensures that the switchback with greater curvature after reconnection can last longer, and the greater the angle, the more magnetic field lines that can be reconnected, and thus the longer the duration. We call this influencing factor flux tube shape factor. The other factor is the velocity shear, i.e., when the solar wind at the convex-outward turning of a switchback is faster than that at the concave-outward turning, the switchback becomes enhanced during propagation, and it weakens when the velocity difference is opposite.

Crashworthiness analysis and optimisation of a multi-level bionic multi-cell tube under axial dynamic impact

In this study, a multi-level bionic multi-cell tube (MBMT-n) is proposed, inspired by the horsetail’s cross-sectional structure, and the multi-cell tube shape and distribution characteristics of bamboo vascular bundles. A systematic crashworthiness analysis of MBMT-n under axial dynamic impact was conducted using LS-DYNA. The findings indicate that MBMT-n can enhance crashworthiness while maintaining the same mass. Additionally, the impact of wall thickness and bionic unit cell’s length–width ratio was investigated. Furthermore, a theoretical prediction model for mean crushing force (MCF) was established using the simplified super-folding unit theory. Lastly, to further enhance the structure’s crashworthiness, multi-objective optimisation of MBMT-3 was performed using the NSGA-II algorithm. The several optimal structures were subsequently identified under various peak crushing force (PCF). This study offers a novel approach to the design of energy-absorbing structures.

An unusual case of ventilation disruption due to an asymmetrical balloon shape of the nasotracheal tube.

An unusual case of ventilation disruption due to an asymmetrical balloon shape of the nasotracheal tube.

Impact of Eccentric Tube Shapes and Heat Pipes on Phase Change Material’s Thermal Charging

The thermal charging performance of phase change material (PCM) in an eccentric tube and shell system is investigated through numerical analysis. Various shapes of eccentric tubes, including circular, semi-circular, triangular, inverted triangular, square, and C-shape, are considered. The PCM mass and shell diameter remain consistent across all tube geometries. Moreover, vertical heat pipes (HPs) are utilized to connect the heat source eccentric tube wall and the PCM stored in the shell. The examination evaluates the consequences of the tube shape and HPs using liquid fraction, temperature time history and contours, enhancement ratio, total energy storage, and mean power as performance indicators. The findings demonstrate that non-circular cases exhibit a shorter melting time than circular tube cases. The C-shape tube has the (Largest) 30.3% less thermal charging time than the circular tube, and the mean power is 39% higher. Moreover, adding HPs increases the mean power by up to 241% more than the circular tube, and reduces thermal charging time by about 72.2%. The inverted triangular tube exhibits the highest energy charge capability within the selected options.

Li/La and Cu modified ZnO semiconductor: Highly boosted of dielectric and sunlight-treatment of thiamethoxam and brilliant green contaminants

Solving the global environmental problem which related to the dissolved organic pollutants into water systems is an essential issue for human-health and aquatic life. This study represents the simple synthesis of new Li/La and Cu modified ZnO compositions as active photocatalysts and proper dielectric materials for electrical energy storage devices. The synthesized powders have one phase nature with hexagonal lattice indexed to ZnO structure. The field emission scanning electron microscopy (FESEM) clearly showed that (Li, La) modified ZnO powder consist of a mixture of particles having open hexagonal tube and spherical shapes. The FESEM picture of (Li, Cu, La) modified ZnO powder revealed lumps like cabbage shape mainly composed of pieces like sheets or papers. The purity and elemental composition were also verified by energy dispersive spectroscopy (EDS) analysis. The addition of (Li, La) and (Li, Cu, La) ions to ZnO semiconductor extremely improved the dielectric constant which is a benefit for application in solid state energy storage systems. (Li, Cu, La) modified ZnO sample is a suitable catalyst for removal of organic waste owing to its high response to visible light spectrum with measured band gap energy of 2.76 eV. The synergistic effect of Li+, Cu2+ and La3+ dopants induced high visible light photodegradation activities against thiamethoxam pesticide and brilliant green dye with measured efficiencies of 92 and 96 % after reaction time of 50 min, respectively. The high stability and mineralization properties of (Li, Cu, La) modified ZnO catalyst leads to the conclusion that this composition has a potential use in wastewater treatment.

Optimization of Elbow Draft Tubes for Variable Speed Propeller Turbine

The design of the elbow draft tubes is challenging due to the complexity of the flow. The whole turbine unit’s power output strongly depends on the draft tube function, especially for the low-head turbines. The article presents a novel approach to optimizing elbow draft tubes for a variable-speed propeller turbine designed for low-head applications. First, the study addresses the specifics of the propeller variable speed turbine by comparing the classical Kaplan turbine. Then, the grid scaling test is conducted to evaluate the uncertainty of the pressure regeneration. Further, a new approach to parameterising the elbow draft tube geometry is introduced. The study employs ANSYS CFX 2021 R1 software for numerical simulation to optimise the elbow draft tube geometry in the CAESES environment. After the sensitivity test and deselecting the non-sensitive parameters, we perform multi-objective genetic algorithm (MOGA) optimization. The optimization process results in a Pareto front of optimised elbow draft tube shapes with the best pressure regeneration for different draft tube construction heights, enabling the selection of suitable candidates for various locations. Minimal difference in the performance of the selected elbow draft tube shapes with the simple straight draft tube confirms a high-quality draft tube optimization achievement.

Response to the design conditions of a tube-bundle thermal energy storage unit with paraffin-copper foam composite as a storage medium

Owing to its potential to limit the issues of intermittency and instability in solar energy by means of phase-change materials (PCMs), latent heat thermal energy storage (LHS) has met increasing attention and been widely employed in thermal-based systems. Most PCMs, however, inherently exhibit poor heat conductance leading to modest rate of charging. To master this drawback, highly conductive metal foams are utilized to upgrade the bulk heat conductance of a PCM resulting in an enhanced rate of heat transport; hence, accelerating the melting process. This enhancement way is employed to promote the response of a tube-bundle thermal energy storage unit configured of staggered tubes filled with high-porosity copper foam embedded in paraffin wax as a storage medium. To charge the thermal energy storage (TES) unit proposed, a relatively hot stream of water is allowed to flow across the bundled tubes through the voids in-between. To check how feasible the proposed design is, the tubes enclosing the TES medium and the water flow in the shell surrounding have been simulated by ANSYS Fluent CFD code. A variety of design factors has been examined to explore their influence on the charging performance attained including structural properties of the metal foam employed along with the configuration of the tube-bundle considered. The foam structural characteristics inspected are the porosity ∅∈(0.89∼0.97) and pore density ω∈(5∼80)PPI, while various tube-bundle configurations have been tested in terms of the packing density N∈(15∼65)TubesLines/meterwidth as well as the shape of PCM tubes used b/a∈(0.25∼1). Results indicate that for a certain tube-bundle configuration, the best response is acquired when denser foam with lower porosity is used, while the best performance can only be achieved with higher porosity due to the better TES capacity offered. For certain foam structural properties of (∅=0.93&ω=80PPI), it has been observed that increasing the packing density can save up to 56 % of the time taken for charging completion with up to 200 % increase in storage capacity leading to up to 48 % improvement in the system overall performance. It has also been found that using paraffin embedded with copper foam as a TES medium accelerates the melting process considerably and saves more than half the time taken to charge the corresponding TES unit based on pure paraffin. It is also worth mentioning that the currently suggested LHS unit is not only of simple configuration, but practically efficient as well, with outstanding gross performance OP∈(104∼105). Through a proper manipulation of design conditions, it has been found that the charging response can be notably improved leading to substantial promotion in the overall performance realized.

The cellular localization and oncogenic or tumor suppressive effects of angiomiotin-like protein 2 in tumor and normal cells.

Angiomiotin (AMOT) family comprises three members: AMOT, AMOT-like protein 1 (AMOTL1), and AMOT-like protein 2 (AMOTL2). AMOTL2 is widely expressed in endothelial cells, epithelial cells, and various cancer cells. Specifically, AMOTL2 predominantly localizes in the cytoplasm and nucleus in human normal cells, whereas associates with cell-cell junctions and actin cytoskeleton in non-human cells, and locates at cell junctions or within the recycling endosomes in cancer cells. AMOTL2 is implicated in regulation of tube formation, cell polarity, and shape, although the specific impact on tumorigenesis remains to be conclusively determined. It has been shown that AMOTL2 enhances tumor growth and metastasis in pancreatic, breast, and colon cancer, however inhibits cell proliferation and migration in lung, hepatocellular cancer, and glioblastoma. In addition to its role in cell shape and cytoskeletal dynamics through co-localization with F-actin, AMOTL2 modulates the transcription of Yes-associated protein (YAP) by binding to it, thereby affecting its phosphorylation and cellular sequestration. Furthermore, the stability and cellular localization of AMOTL2, influenced by its phosphorylation and ubiquitination mediated by specific proteins, affects its cellular function. Additionally, we observe that AMOTL2 is predominantly downregulated in some tumors, but significantly elevated in colorectal adenocarcinoma (COAD). Moreover, overall analysis, GSEA and ROC curve analysis indicate that AMOTL2 exerts as an oncogenic protein in COAD by modulating Wnt pathway, participating in synthesis of collagen formation, and interacting with extracellular matrix receptor. In addition, AMOTL2 potentially regulates the distribution of immune cells infiltration in COAD. In summary, AMOTL2 probably functions as an oncogene in COAD. Consequently, further in-depth mechanistic research is required to elucidate the precise roles of AMOTL2 in various cancers.

Predicting plastic behavior of magnesium alloy tube bending with comprehensive constitutive models

This paper aims to predict defects occurring in magnesium alloy tube bending through finite element simulations. Deformation tests were conducted to identify and characterize plastic anisotropy, tension-compression asymmetry, and anisotropic hardening behaviors of extruded Mg–Al–Zn-RE alloy rectangular tubes. Limited by size, the deformation tests along the wall thickness of specimens were conducted through crystal plasticity analysis. To thoroughly investigate the material constitutive features affecting bending, two constitutive models, Yoon2014 and Hill48, were established and calibrated. The non-associative flow rule was adopted, and anisotropic hardening was depicted using the yield-surface interpolation method. In comparison, the Yoon2014 model accurately predicted the strain distribution and tube shape collapse of the bent tube with negligible deviation from the experimental data, prior to the Hill48 model. This underscores the necessity of considering comprehensive plasticity models in tube bending simulations.