Tube Diameter Research Articles

Detailed 3D URANS analysis of two-phase flow in an airlift pump

An airlift pump is a vertical tube that utilizes the buoyant effects of a gas to lift a liquid. Unlike a standard mechanical pump, the liquid flow rate through the airlift pump is not directly controlled; rather, it depends on the supplied gas flow rate, the tube length and diameter, and the relative height of the liquid supply free surface (submergence ratio). The present study uses the commercial CFD code ANSYS CFX to model the isothermal, 3D, transient flow in an airlift pump using water and air. The model applies pressure boundary conditions at both ends of the tube and specifies the mass flow rate of air through multiple openings in the side of the tube. The bottom of the tube is an inlet of water only and the outlet is a two-phase flow opening. A time-dependent, homogeneous, VOF two-phase RANS CFD modelling approach is used with the air treated as an ideal gas. This work found that a complete 3D domain was necessary for consistent prediction of the airlift performance and physically realistic two-phase flow structures. Statistical analysis of the two-phase flow structures was applied to characterize airlift pump instability and better understand the physics of the airlift pump.

Optimal design of parabolic through solar collector networks: A design approach for year-round operation

In this article, area optimization in parabolic trough solar collector (PTC) networks used in industrial processes is explored. The Particle Swarm Optimization (PSO) technique to maximise economic benefits while minimising total operating costs is employed. The objective also considers flexibility across wide temperature ranges and process heat loads. To achieve this the relationship between solar collection area and associated costs, including initial investment, maintenance, and energy efficiency is meticulously analysed. This work proposes strategies for the optimal adjustment of PTC collector area, accounting for thermal variations and specific demands of industrial processes. The results indicate that the optimised geometry of a PTC, which maximizes the present value of annual energy savings, has the following dimensions: length: 12.5 m; aperture: 5.8 m; tube diameter: 0.014 m; focal distance: 1.449 m; glass envelope inner diameter: 0.111 m. For a process thermal load ranging from 0.4 MW to 4 MW, the optimal network structure that maximizes energy capture in both summer and winter consists of 12 collectors in series (125 m long), with the number of parallel lines proportional to the heat duty. In this article, area optimization in parabolic trough solar collector (PTC) networks used in industrial processes is explored. The Particle Swarm Optimization (PSO) technique to maximise economic benefits while minimising total operating costs is employed. The objective also considers flexibility across wide temperature ranges and process heat loads. To achieve this the relationship between solar collection area and associated costs, including initial investment, maintenance, and energy efficiency is meticulously analysed. This work proposes strategies for the optimal adjustment of PTC collector area, accounting for thermal variations and specific demands of industrial processes. The results indicate that the optimised geometry of a PTC, which maximizes the present value of annual energy savings, has the following dimensions: length: 12.5 m; aperture: 5.8 m; tube diameter: 0.014 m; focal distance: 1.449 m; glass envelope inner diameter: 0.111 m. For a process thermal load ranging from 0.4 MW to 4 MW, the optimal network structure that maximizes energy capture in both summer and winter consists of 12 collectors in series (125 m long), with the number of parallel lines proportional to the heat duty. The network size is determined by the required heat load more than the inlet and required process temperature.

Study on the characteristics and predictive model of autoignition induced by shock wave from high-pressure hydrogen leakage

Faced with climate change and increasing environmental pollution, countries around the world are actively exploring strategies for clean, renewable energy. However, under high-pressure conditions, hydrogen leaks can lead to spontaneous combustion, which significantly raises the safety risk of hydrogen applications. This study employs fluid dynamic simulation methods to investigate the development process of shock waves within tubes. It analyzes the effect of release conditions on the propagation speed and shock wave intensity, revealing the impact of shock wave intensity on the temperature distribution and gas composition variation within the hydrogen-air mixture boundary layer. The results show that the tube length and bends have relatively little impact on the shock waves, while discharge pressure and tube diameter significantly affect the propagation speed and intensity of shock waves. Combined with dimensional analysis and data fitting, a predictive model for autoignition of high-pressure hydrogen leakage is established: (Pr/Pa)((DXrx(H₂)rO₂))/Vs2) = 1505(X/D)−1.329.

Experimental investigation on the development characteristics of high-pressure hydrogen jet flame under different ignition conditions

With the rapid development and application of hydrogen in the chemical and energy industry, the safety of hydrogen industrial facilities has been widely concerned. In this study, the safety of hydrogen accidently released from a high-pressure tube storage system (tube diameter:10 mm, storage tank volume:4 L) was explored experimentally. The combustion behavior of the transient hydrogen jet and explosion overpressure under self-ignition and electric spark induction were investigated. Besides, the explosion overpressure and jet flame evolution laws of the hydrogen cloud induced by the release of unsteady turbulent hydrogen jets into the open environment were analyzed. The results revealed that the peak value of hydrogen self-ignition explosion overpressure was higher than that of electric spark ignition overpressure. Compared with spark ignition, hydrogen self-ignition flame structures can be maintained for longer time. However, spark ignition at low release pressures was more likely to cause hydrogen ignition and explosion compared to self-ignition. Finally, the combustion behavior and potential hazards of the ignited free transient hydrogen jet under different ignition modes were analyzed. This study can provide a reference for the prevention and control of hydrogen explosion accidents in practice.

Investigation of Laminar Forced and Mixed Convection in Horizontal Mini Tubes with Uniform Wall Heat Flux Boundary Condition

In this study, a numerical model is established to study the forced and mixed convection heat transfer in the laminar region for horizontal mini tube with different diameters (1.2 mm to 3.0 mm) under the uniform wall heat flux boundary condition. The Reynolds number is set from 100 to 2,000 and the uniform wall heat flux boundary condition is set at 10 and 20 kW/m2. The model is verified with well-established correlation to guarantee good accuracy. The existence of mixed convection is examined by (1) the ratio between the heat transfer coefficients at the top and the bottom of the tube, and (2) the temperature contour plot. Based on the simulation results, the existence of buoyancy superimposed on the main flow is strongly related to the tube diameter, the dimensionless location, the Reynolds number, and the heat flux applied. Under the same heating condition, for small diameter tube with insufficient length, buoyancy effect can never establish. The existing flow regime maps for macro tube were used to predict the forced and mixed convection regimes from the simulated mini tube results and discrepancy was found. A new flow regime map is hence developed for mini tubes, and it classified the simulation results with good accuracy.

Entanglement Kinetics in Polymer Melts Are Chemically Specific.

We investigate the universality of entanglement kinetics in polymer melts. We compare predictions of a recently developed constitutive equation for disentanglement to molecular dynamics simulations of both united-atom polyethylene and Kremer-Grest models for polymers in shear and extensional flow. We confirm that entanglements recover on the retraction time scale, rather than the reptation time scale. We find that the convective constraint release parameter β is independent of molecular weight, but that it increases with the ratio of Kuhn length bK to packing length p as β ∼ (bK/p)α, with an exponent α = 1.9, which may suggest that disentanglement rate correlates with an increase in the tube diameter. These results may help shed light on which polymers are more likely to undergo shear banding.

Detectability of intracranial vessel wall atherosclerosis using black-blood spectral CT: a phantom and clinical study

BackgroundComputed tomography (CT) is the usual modality for diagnosing stroke, but conventional CT angiography reconstructions have limitations.MethodsA phantom with tubes of known diameters and wall thickness was scanned for wall detectability, wall thickness, and contrast-to-noise ratio (CNR) on conventional and spectral black-blood (SBB) images. The clinical study included 34 stroke patients. Diagnostic certainty and conspicuity of normal/abnormal intracranial vessels using SBB were compared to conventional. Sensitivity/specificity/accuracy of SBB and conventional were compared for plaque detectability. CNR of the wall/lumen and quantitative comparison of remodeling index, plaque burden, and eccentricity were obtained for SBB imaging and high-resolution magnetic resonance imaging (hrMRI).ResultsThe phantom study showed improved detectability of tube walls using SBB (108/108, 100% versus conventional 81/108, 75%, p < 0.001). CNRs were 75.9 ± 62.6 (mean ± standard deviation) for wall/lumen and 22.0 ± 17.1 for wall/water using SBB and 26.4 ± 15.3 and 101.6 ± 62.5 using conventional. Clinical study demonstrated (i) improved certainty and conspicuity of the vessels using SBB versus conventional (certainty, median score 3 versus 0; conspicuity, median score 3 versus 1 (p < 0.001)), (ii) improved sensitivity/specificity/accuracy of plaque (≥ 1.0 mm) detectability (0.944/0.981/0.962 versus 0.239/0.743/0.495) (p < 0.001), (iii) higher wall/lumen CNR of SBB of (78.3 ± 50.4/79.3 ± 96.7) versus hrMRI (18.9 ± 8.4/24.1 ± 14.1) (p < 0.001), and (iv) excellent reproducibility of remodeling index, plaque burden, and eccentricity using SBB versus hrMRI (intraclass correlation coefficient 0.85–0.94).ConclusionsSBB can enhance the detectability of intracranial plaques with an accuracy similar to that of hrMRI.Relevance statementThis new spectral black-blood technique for the detection and characterization of intracranial vessel atherosclerotic disease could be a time-saving and cost-effective diagnostic step for clinical stroke patients. It may also facilitate prevention strategies for atherosclerosis.Key points• Blooming artifacts can blur vessel wall morphology on conventional CT angiography.• Spectral black-blood (SBB) images are generated from material decomposition from spectral CT.• SBB images reduce blooming artifacts and noise and accurately detect small plaques.Graphical

Detailed visualization experiments on the start-up process and stable operation of double-layered pulsating heat pipes under vertical and horizontal orientations

The thermal characteristics in a double-layered 3D-CLPHP are investigated by visualization experiments. The results are compared with those of a single-layered CLPHP under the vertical and horizontal orientations and a filling ratio (FR) of 35%, 50%, or 65%. The tube's inner diameter (ID) is 6 mm, slightly over the limiting value for water. The orientation is found highly determinative to the flow pattern of liquid slug trains in each tube layer. The flow behavior appears similar for the two layers under the vertical orientation but apparently different under the horizontal orientation. When horizontally placed, the liquid slug trains tend to drain down to the lower layer, thereby not only triggered but sustained continuous pulsation motion. Intense cross-layered flow motion, attributed to the interaction between the downward gravity and upward gaseous expansion or buoyancy effect, is recorded during the operation. Sufficient working fluid distribution inside each layer for the overall FR of 65% is recommended. Instead, the single-layered CLPHP fails to maintain a stable oscillation motion without the assistance of gravity. The double-layered CLPHP outperformed the single-layered CLPHP by 12.8−15.1% in thermal resistance even under the vertical orientation.

TiO2 nanotubes with customized diameters for local drug delivery systems

AbstractIn this study, we evaluated the drug release behavior of diameter customized TiO2 nanotube layers fabricated by anodization with various applied voltage sequences: conventional constant applied potentials of 20 V (45 nm) and 60 V (80 nm), a 20/60 V stepped potential (50 nm [two‐diameter]), and a 20–60 V swept potential (49 nm [full‐tapered]) (values in parentheses indicate the inner tube diameter at the top part of nanotube layers). The structures of the 50 nm (two‐diameter) and 49 nm (full‐tapered) samples had smaller inner diameters at the top part of nanotube layers than that of the 80 nm sample, while the outer diameters at the bottom part of nanotube layers were almost the same size as the 80 nm sample. The 80 nm sample, which had the largest nanotube diameter and length, exhibited the greatest burst release, followed by the 50 nm (two‐diameter), 49 nm (full‐tapered), and 45 nm samples. The initial burst released drug amounts and release rates from the 50 nm (two‐diameter) and 49 nm (full‐tapered) samples were significantly suppressed by the smaller tube top. On the other hand, the largest proportion of the slow released drug amount to the total released drug amount was observed for the 50 nm (two‐diameter) sample. Thus, 50 nm (two‐diameter) achieved suppressed initial burst release and large storage capacity. Therefore, this study has, for the first time, applied TiO2 nanotube layers with modulated diameters (two‐diameter and full‐tapered) to the realization of a localized drug delivery system (LDDS) with customized drug release properties.

Exploring the impact of parameters on flow boiling heat transfer in microchannels and coated microtubes: A comprehensive review

Abstract The aim of this study is to present a comprehensive review of the impact of various parameters on flow boiling heat transfer in microchannels and coated microtubes. The objectives of this study are to analyze the existing literature, identify the research methods employed, summarize the findings, and highlight the novelty and potential improvements in the field of microscale heat transfer. The review encompasses a wide range of parameters including fluid flow rate, wall heat flux, surface roughness, tube diameter, and tube coating. By examining these parameters, the study investigates their effects on the heat transfer performance in microchannels and coated microtubes. A systematic analysis is conducted to understand the relationships between these parameters and the heat transfer characteristics. The findings of this review contribute to the current state of knowledge in microscale heat transfer. The analysis reveals significant insights into the impact of various parameters on flow boiling heat transfer, providing valuable information for researchers and engineers in fields such as microelectronics cooling, energy conversion, and biomedical engineering. Moreover, this review identifies areas for further investigation and highlights the challenges and opportunities that lie ahead in this research domain. The novelty and improvement of this work lie in its comprehensive analysis of the interplay between different parameters and their effects on flow boiling heat transfer. By synthesizing the existing literature, this review serves as a valuable resource for researchers and engineers working on microscale heat transfer. It offers a deeper understanding of the subject matter and paves the way for future advancements in the design and optimization of microchannels and coated microtubes for enhanced heat transfer performance.

Study Conducts Mechanical Evaluation of Nonmetallic Tubulars

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 214488, “Mechanical Evaluation and Intervention in Nonmetallic Tubulars Using Current Technologies,” by Mohamed Larbi Zeghlache, SPE, and Khaled Al-Muhammadi, Saudi Aramco, and Iqbal Pervaiz, SPE, Baker Hughes, et al. The paper has not been peer reviewed. _ With increasing interest in nonmetallic products, such as fiberglass tubing, for downhole applications, ensuring well integrity in a similar way as is achieved for standard carbon steel completions is essential. One important aspect of well integrity is the ability to routinely access the downhole condition of the tubing and perform basic interventions. The complete paper demonstrates testing and validation of different mechanical evaluations of the integrity of fiberglass tubing using logging and intervention tools. Introduction Fiber-reinforced polymer composites have been used efficiently for various structural applications, including primary structures for which safety is a major design requirement. Fiber-reinforced laminate is very sensitive to out-of-plane loading, however, because it exhibits relatively low transverse properties. The resulting impact damage in fiber-reinforced polymer composite usually reduces its postimpact mechanical properties. The damage phenomenology in fiber-reinforced polymer composites involves many different mechanisms of degradation. Contrary to metallic materials, fiber-reinforced polymer composites can experience damage evolution followed by a catastrophic failure without prior notice. The inspection and monitoring of such damage during a structure’s lifetime are very challenging. Moreover, classical nondestructive testing techniques are difficult to implement for real-time structural health monitoring (SHM). It is, therefore, important to develop a reliable SHM technique that can both increase safety and reduce operational costs by optimizing inspection and repair. Well-Integrity Evaluation Of common barrier-inspection technologies, cement evaluation using sonic and ultrasonic measurements is very challenging across coated or nonmetallic casing. In the case of nonmetallic pipes such as fiberglass and composite pipes, this measurement is yet to be investigated for proper transducer design and signal processing. Magnetic and electromagnetic technologies cannot be used for casing inspection because the pipe material is an insulator and prevents any current flow. The simplest and most straightforward technologies remaining are mechanical tools for inner wall inspection. For this reason, testing was conducted to evaluate the effectiveness of multifinger caliper (MFC) logging in fiberglass casing and to simulate intervention operation through puncher and cutter services. MFC Log in Steel Casing An MFC is a mechanical tool that provides, through its fingers, high-resolution accurate radial measurements of internal diameter of tubing or casing string. MFCs are used to detect very small changes to the internal surface condition of the tubing or casing with a high degree of accuracy. The tool may be run with extended fingers to increase the measurement range. An MFC tool works in any type of fluid present within the wellbore. MFC detects the scale, wax, or solid buildup on the inner surface of the pipe and any deformation or ovality in the pipe.

Optimization of the gas system for gas–water combined atomization technique in FeSiBC amorphous powder production

The gas–water combined atomization is an advanced technology for Fe-based amorphous powder preparation, and its gas/water system parameters have significant impacts on powder properties. In this study, numerical simulations and industrial trials were combined to optimize the gas atomization parameters. The results showed that increasing the atomization pressure promotes the transition of the flow field to the closed wake. Moreover, the median particle size was significantly refined and the cooling rate was improved. Extending the extrusion length facilitated the decrease in suction pressure, while excessively long extrusion lengths led to instability in the atomization process. The decrease in delivery tube diameter enhances droplet breakup and cooling, but increases the risk of clogging. Industrial trials at different atomization pressures showed that low atomization pressure led to the formation of needle-shaped powder, and the FeSiBC amorphous powder prepared at 3.0 MPa exhibited optimal comprehensive properties, with saturation magnetization of 166.1 emu·g−1 and coercivity of 4.5 Oe.

Pressure drop prediction by a polynomial model for two-phase flow in vertical oil wells

In this paper, a polynomial model is developed to predict the pressure drop in oil wells with two-phase flow. The variables used in the model are gas-oil ratio production, oil production, tubing diameter, solution gas-oil ratio, oil formation volume factor, and oil viscosity. A polynomial model is presented to predict the pressure drop with a coefficient of determination of 0.9901. The residual analysis and level surfaces of the pressure drop against the polynomial model's input variables are presented to validate the model. A regression of the experimental and predicted pressure drops values using the polynomial model is presented. This model contributes to a simpler methodology for the calculation of pressure drops and the consequent application in the modeling of production curves in oil wells for NODAL analysis.

Bending of bimetallic steel sheet on three-roll mills in the production of large diameter tubes

Bending of bimetallic steel sheet on three-roll mills in the production of large diameter tubes

A comparative study between curcumin and curcumin nanoparticles on reproductive performance and antioxidant system of aged roosters

Increased lipid peroxidation and decreased antioxidant status can result in reduced reproductive activity and fertility in aged male broiler breeders. This study was conducted to evaluate the effects of curcumin supplements (natural or nanoparticles) on the sperm characteristics, antioxidant system, fertility, and hatchability of aged roosters (54-64 wk), and to estimate the relative bioavailability value (RBV) of nano-curcumin on the measured parameters including the hypo-osmotic swelling test (HOST), motility, viability, sperm count, volume, the concentration of testosterone, glutathione peroxidase (GPx), and superoxide dismutase (SOD), diameter of the spermatogenic tube (DST), epithelium thickness (EpiTh), spermatogonia count (SPcount), fertility, hatchability, and relative weight of testis (RW-testis). A total of 30 roosters were individually caged and randomly assigned to 5 treatments comprising control (without curcumin as the basal diet), basal diet + 15 mg/kg curcumin (CUR15), basal diet + 30 mg/kg curcumin (CUR30), basal diet + 15 mg/kg nano-curcumin (Nano15), and basal diet + 30 mg/kg nano-curcumin (Nano30) for 10 wk. The slope ratio method was used to estimate the bioavailability of nano-curcumin by regressing each response on supplemental curcumin intake. Increasing dietary curcumin (P < 0.001) elicited a linear response to all studied traits. The RBV for volume, viability, motility, HOST, RW-testis, and GPx were estimated as 135 (CI: 115-156%), 143 (CI: 114-173%), 159 (CI: 122-196%), 132 (CI: 107-157%), 195 (CI: 126-264%), 176 (CI: 103-249%), and 178% (28-328%), respectively. Our findings revealed that curcumin nanoparticles enhance the reproductive efficiency of aged breeder roosters. In addition, the curcumin nanoparticles RBV exceeded that of natural curcumin, suggesting that lower concentrations of curcumin nanoparticles could have a significant effect on reproductive characteristics.

Experimental study of light transmitting concrete with ultra-high content of polymethyl methacrylate

Light Transmitting Concrete (LTC) is an innovative material for crafting unique and sustainable architectural and civil structures. Previous studies primarily utilized optical fibers with diameters below 1.5 mm, which did not exceed 10 % of the volumetric content in concrete. This study aims to develop LTC with ultra-high light transmission capabilities while preserving its mechanical strength. An important innovation is the use of polymethyl methacrylate (PMMA) with larger diameters than normal optical fibers. Specifically, PMMA fibers of 2.0 mm diameter and PMMA tubes of 10–20 mm diameter were employed to increase the spacing between these materials when arranged in an ultra-high volumetric content within the concrete, facilitating easier compaction of the fresh concrete. Experiments of the material's mechanical properties, microstructure, and optical performance were conducted. The findings suggest that although the increased PMMA content might reduce the concrete’s mechanical strength due to a smaller effective cross-sectional area, the LTC still achieves compressive strength exceeding 40 MPa. This underscores the viability of LTC with a substantially higher content of light transmitting functional materials compared to previous studies, while still maintaining a mechanical strength greater than normal concrete. The light transmission efficiency of LTC is nearly directly proportional to its PMMA content, and able to reach up to 30 % of the light source's intensity. Additionally, LTC with PMMA fibers provides uniform light distribution across its surface because of scattering, while LTC with larger-diameter PMMA tubes focuses light around the core areas due to direct lighting.

Comparison of heat transfer characteristics of a heat exchanger with straight helical tube and a heat exchanger with coiled flow reverser

Vertical shell and coiled tube heat exchangers are an important aspect of numerous industrial processes and are renowned for their high heat transfer efficiency, versatility, compact design, easy manufacturability and maintenance. As a novel technique, a coiled flow reverser was used to enhance the thermal performance of shell and coiled tube heat exchangers. Therefore, the impact of employing a coiled flow reverser on the heat transfer characteristics and pressure drop in a counter-current shell and tube heat exchanger is investigated using both numerical and experimental approaches. The results are compared to a straight helical coiled tube heat exchanger. The numerical simulations were carried out by employing computational fluid dynamics (CFD) techniques, and the SIMPLE scheme was implemented through the second-order upwind discretization method. The laboratory device used for experimentation features a shell with an inner diameter of 15 cm, and the coil pitch and coil diameter of both coiled tubes are set at 3 cm and 12.1 cm, respectively. Results reveal that the overall heat transfer coefficient of the heat exchanger with a coiled flow reverser is 39.5 % to 49.9 % higher than that of the heat exchanger with a straight helical tube. The effectiveness ratio of the heat exchanger with coiled flow reverser to the straight helical tube heat exchanger ranges from 1.254 to 1.379. Optimal results are observed at a cold flow rate of 6 LPM and a hot flow rate of 1 LPM for both heat exchangers. Additionally, the coiled flow reverser enhances heat transfer performance at the cost of increased pressure drop. Numerical results are in good agreement with experimental findings, establishing the reliability of the study.

A parametric optimization framework for fin-and-tube heat exchangers based on response surface methodology and artificial intelligence

This study presents a numerical investigation and provides a novel framework for the rapid parametric optimization of attack angles (α) and aspect ratios (e) in plate fin-and-tube heat exchangers (PFTHEs) featuring elliptical tubes. The methodology incorporates three-dimensional numerical simulations, response surface methodology (RSM), backpropagation neural network (BPNN), and Entropy-VIKOR. The study focuses on a PFTHE with a single elliptical tube, varying the attack angles (α) from −30° to 0° in 5° increments and the aspect ratios (e) from 0.4 to 1.0 in a step of 0.1. Air velocities (u) range from 0.4 to 3.2 m/s with an interval of 0.2 m/s, corresponding Reynolds number from 200 to 2200. The results indicate that using elliptical tubes reduces Δp and enhances heat transfer capacity, with the most significant improvements at an e of 0.4. Exponential relationships between dimensionless parameters Nu or f and Re are established for different range of α at specific e values. The synergistic effect of e, α, and Re or u on PFTHE performance is confirmed through RSM and BPNN analysis. Their R2 values are no less than 0.896 and reach a maximum of 0.998, indicating excellent predictive accuracy. Utilizing Entropy-VIKOR method, the framework identifies a suitable design solution with e = 0.6, α = -20°, and u = 3.2 m/s. This solution exhibits a 5 % increase in h and a 58 % reduction in Δp relative to the corresponding circular tube. The study provides specific expressions relating design variables to thermal–hydraulic behavior and indicates carefully selecting the α and e can improve the overall performance. In summary, these findings have significant implications for reducing optimization design period for PFTHEs with small tube diameters.

Experimental study on the leakage behavior of aerosol particles in capillary tubes

The leakage rate of aerosol particles is one of the most important parameters for source term evaluation of containment in severe accidents. In this study, gas leakage characteristics experiments were conducted on capillaries with different inner diameters and tube lengths under different pressure differential conditions. The effects of upstream and downstream pressure differential, capillary tube diameter, tube length, aerosol particle size, whether condensation or not, and release time on aerosol leakage rate were studied. The results show that when the pressure difference between the two ends of the capillary is greater than 0.2 MPa, the leakage rate of the capillary shows a pattern of first increasing and then decreasing with the increase of the pipe diameter; The influence of aerosol particle size on leakage rate mainly affects the inertial deposition effect, which increases with the increase of particle size, leading to a decrease in leakage rate; The condensation effect of steam in capillaries can lead to enhanced effects such as condensate capture, thermophoresis, and diffusion electrophoresis, which have a positive strengthening effect on the retention of aerosol particles.

An assessment of the performance of heat transfer enhancement for optimizing high-temperature thermal energy storage

Background: High-temperature phase change materials (PCMs) are increasingly recognized for their potential in applications such as solar energy utilization, industrial waste heat recovery, and power load regulation. These materials can store and release significant amounts of latent heat, making them highly efficient for thermal energy storage. Purpose: This study aims to propose and analyze a novel structure to enhance latent heat energy storage using a graphite sheet combined with a PCM (KNO3-NaNO3) with a melting point of 220 K. The focus is on improving heat transfer efficiency and understanding the parameters affecting the exothermic process. Research Design: A numerical simulation approach was employed, using Fluent 7.1 software to analyze the exothermic process. The simulation method was validated with two examples before being applied to study the energy storage system incorporating graphite sheets. Study Sample: The study analyzed the performance of a high-temperature thermtotal energy storage (HTTES) system using graphite sheets of varying thicknesses, tube spacing, tube temperatures, and PCM thermal conductivities. Data Collection and/or Analysis: The study utilized numerical simulations to examine how different parameters i.e. thickness of graphite sheets, spacing between tubes, tube temperatures, and the thermal conductivity of PCM—affect heat transfer efficiency and exothermic time. Results: The integration of graphite sheets with a thickness of 2 mm was found to significantly improve heat transfer efficiency. The results indicated that increasing the spacing between graphite sheets and tube diameter influenced the total exothermic time. A logarithmic relationship was observed between the thermal conductivity coefficient and exothermic time, suggesting diminishing returns beyond 3.5 W/(m·K). Additionally, increasing the quantity of graphite sheets enhanced heat transmission and overall system efficiency. Conclusions: The study provides valuable insights into the performance of HTTES systems, demonstrating that incorporating graphite sheets can significantly enhance heat transfer and system efficiency. These findings guide the design of more effective thermal energy storage systems, supporting the broader adoption of HTTES technologies and contributing to the transition toward sustainable energy solutions. Further research and development in this field are essential to drive advancements and promote the widespread implementation of high-temperature thermal energy storage systems. Practical applications The enhanced heat transfer techniques developed in this research offer practical applications across various sectors. These techniques, utilizing PCMs and innovative graphite structures, enhance the efficiency and reliability of high-temperature thermal energy storage systems. This advancement enables continuous power generation in concentrated solar power (CSP) plants, optimizes energy utilization in district heating and cooling systems, and improves industrial waste heat recovery. By implementing these techniques, energy costs can be reduced, system performance can be optimized, and greenhouse gas emissions can be lowered, contributing to a more sustainable energy future.