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This paper focuses on researching the various factors that influence the material melting rate during the hot air melting process. To achieve this purpose, the paper proposes a melting model for Acrylonitrile-Butadiene-Styrene (ABS) plastic under hot air heating based on Computational Fluid Dynamics (CFD). Orthogonal experiments were conducted based on the parameter range of each factor obtained in the pre-experiment. The results showed that the outlet distance, hot air velocity, hot air temperature, and their interaction items are important factors that affect the melting rate of ABS materials. Based on the simulation results, a multiple nonlinear regression model was constructed to predict the melting rate under different parameters. Comparing the simulation values with the predicted values of the multiple nonlinear regression model, the error between the two was no >10%, indicating the effectiveness of the prediction model. The research results can help guide the hot air welding melting process for different materials and characteristics, and provide a certain reference value for the development of hot air welding technology. • Welding of airbag labels was performed using hot air welding technology; • Realizes real-time monitoring of melt quality during the material melting process • Using CFD modeling to study the effects of outlet distance, hot air velocity, and hot air temperature on the melting rate. [ABSTRACT FROM AUTHOR]

Flow control is essential in high-pressure CO 2 systems. Flow regulators are widely used for flow adjustment in piping systems. In this paper, a novel combinational flow regulator is proposed, which contains four parallel branch channels, and each channel is arranged with a solenoid valve and an orifice plate. In order to analyze the internal flow characteristics of high-pressure CO 2 and flow adjustment performance of the proposed flow regulator, a numerical model of the regulator is established, and the validation of numerical model is verified by experimental results. Then, the pressure and velocity characteristics are studied numerically. Finally, the flow adjustment performance is investigated numerically and experimentally from three aspects: variation of flow rate with differential pressure, variation of the product of flow coefficient and throttling area, and dynamic variations of pressure, temperature and flow rate of the flow regulator. This paper serves as a valuable reference for researchers utilizing flow regulators to adjust the flow rate of CO 2 or other fluids. • Numerical model of a novel flow regulator is established, verified by experiments. • Pressure and velocity characteristics are discussed, CO 2 as working medium. • Variation of flow rate with differential pressure and flow area is analyzed. • Dynamic working situation of the regulator is investigated by experiments. [ABSTRACT FROM AUTHOR]

Liquid metals have excellent thermal properties such as low vapor pressure, high thermal conductivity, low dynamic viscosity, and a wide range of temperatures in which they maintain liquid state. Some scholars have investigated the application of liquid metal heat exchangers. However, there is still potential for further exploration of the applicable temperature range of a liquid metal heat exchanger. In this paper, a liquid lithium-air shell-and-tube heat exchanger with a liquid lithium inlet temperature of 1473 K was designed. The heat transfer performance characteristics were studied via numerical and experimental methods. Furthermore, the numerical results were compared with the theoretical calculation results. The maximum relative differences were determined to be acceptable for the outlet temperatures, the tube and total heat transfer coefficient. The experimental temperatures for different monitoring points were compared with the steady state simulation results of the basic case. The relative errors were in the range of 0.1 % to 7.5 % for most of the temperature monitoring points. The findings of this study could offer crucial insights into the design of thermal management systems for many areas, such as the aerospace, nuclear engineering and shipbuilding industries. [ABSTRACT FROM AUTHOR]

Numerical simulation, also known as computer simulation, uses an electronic computer to investigate and solve engineering problems, physical problems, and a wide range of other problems through numerical calculations and image visualization methods. Numerical simulation is often employed to support machine design, parameter selection, and size optimization, enabling the comparison of various schemes and processes. In recent years, numerical simulation has emerged as a powerful and promising tool for studying drum drying processes. Its applications include understanding complex gas–solid fluidization properties, exploring potential mechanisms of gas–solid flow, and optimizing drum drying design and scaling. This paper comprehensively reviews the numerical modeling of gas–solid flow, focusing on the numerical simulation of the flow characteristics in the drum drying process. Moreover, it identifies current challenges and outlines future development trends in the numerical simulation of this drying process, providing valuable insights for the optimization and application of this simulation technique in the broader field of drying technology. [ABSTRACT FROM AUTHOR]

This paper employs a computational fluid dynamics numerical framework integrating the Euler-Euler two-fluid model with the particle dynamics method to analyze the heat and mass transfer characteristics of water-based graphene nanofluid slurries in helical corrugated tubes. The results indicate that, with ice crystal content ranging from 10% to 30% at the inlet, the heat transfer performance is positively correlated with the slurry concentration, and the increase in nanofluid concentration has minimal impact on the pressure drop inside the tube. The helical structure results in the maximum flow velocity occurring in the groove area. Compared to straight tubes, the increase in heat transfer area does not only promote the generation of vortices but also enhances turbulent intensity, reduces the thickness of the thermal boundary layer, and improves heat transfer efficiency. Graphene nanofluid slurries exhibit superior heat transfer capability compared to pure water slurries, with surface heat transfer coefficient increasing with graphene concentration. The maximum HTC of helical corrugated tubes is 1.4 times that of straight tubes, with an average Nusselt number (Nu) 1.44 times higher than that of straight tubes. Lastly, an empirical correlation for Nu is established to predict the thermal performance of water-based graphene nanofluid slurries flowing through helical corrugated tubes. • Pressure drop, ice crystal concentration distribution, flow velocity, temperature distribution, and heat transfer performance are discussed. • Aqueous graphene nanofluid ice slurry demonstrates outstanding flow and heat transfer performance. • Helical structure significantly influences the flow and heat transfer of the ice slurry. • The average Nu of spiral bellows is 1.44 times that of straight pipe. [ABSTRACT FROM AUTHOR]

A novel double-wall-hole honeycomb seal (D-WHHCS) is proposed in this paper. D-WHHCS is designed based on a traditional honeycomb seal (HCS) by drilling double holes in the honeycomb sidewalls. The leakage characteristics of D-WHHCS are investigated via the computational fluid dynamics (CFD) method. The sealing performance of D-WHHCS under different seal clearances, wall hole positions, operating pressures and rotating speeds is studied. The sealing mechanism of D-WHHCS is revealed. The results show that D-WHHCS has better sealing performance than HCS under all the considered operating conditions, with a maximum leakage reduction of 3.95%. A fluid concentration effect when the axial cavity number (N) = 14 is observed in D-WHHCS, which causes a 9.16% improvement in the maximum turbulent kinetic energy compared with HCS at the outlet extension. A large vortex in the cavities of D-WHHCS with N = 14 is guided by the jets at the centerlines of the drilling hoes. The average turbulent dissipation in the cavities of D-WHHCS is a maximum increase of 95.30%, even though the vortexes in the cavities with N = 13 are weakened by the counteractive effect of two jets. The leakage reduction performance of D-WHHCS decreases with increasing clearance. An abnormal low-pressure region is produced in the first cavity because the intensive jet covers the first two cavities and suppresses the throttling effect of the first-stage honeycomb cavity. The leakage of D-WHHCS further decreases along with holes closing to rotor surface. • The leakage of double-wall-hole honeycomb seal (D-WHHCS) decreases 3.95%. • A fluid concentration effect is observed in the sealing gap of D-WHHCS. • A huge turbulent dissipation in unit cavities is observed in the D-WHHCS. • The sealing performance of D-WHHCS is weakened with seal gap increasing. • The smaller the distance between holes and rotor is, the larger the vortexes is. [ABSTRACT FROM AUTHOR]

In this paper, we present a comprehensive study on the heat transfer in the spiral coiled tubes, employing both numerical simulations and experimental analysis. The investigation includes an exploration of water flow at different mass flow rates, ranging from 0.025 to 0.11 kg / s , to capture a wide range of operating conditions. The numerical simulations were conducted using advanced computational fluid dynamics (CFD) techniques, providing detailed insights into the heat transfer behavior within the spiral tube. Concurrently, experimental tests were performed to validate the numerical results and compare them with existing findings from previous studies. The primary aim of our study is to establish correlations for calculating the Nusselt number and friction coefficient in the spiral coiled tubes. These correlations serve as essential tools for engineers and researchers in predicting heat transfer characteristics and pressure drop, thus facilitating the design and optimization of heat exchangers and heat recovery systems that incorporate spiral coiled tubes. Overall, the results obtained from this investigation enhance our understanding of heat transfer in spiral tubes and contribute to the development of reliable predictive models. The proposed correlations offer practical and efficient means of assessing heat transfer performance, making significant strides towards achieving more energy-efficient and sustainable industrial processes. • Fluid flow and heat transfer in a spiral coiled tube were studied. • Effects of mass flow rate of water on heat transfer in a spiral coiled tube were investigated. • Correlations for calculation of Nusselt number and friction coefficient for water flow in a spiral coiled tube were developed. [ABSTRACT FROM AUTHOR]

This paper reports a study on the effect of orifice thickness-to-diameter ratio (τ / d) on the turbulent flow through an orifice plate. Details of the flow characteristics downstream of the orifice are investigated both experimentally and numerically for a Reynolds number of 25,000. For this purpose, seven orifice plates are manufactured with τ / d ranging between 0.27 and 1.37. Particle Image Velocimetry (PIV) is used to experimentally study the flow patterns downstream of the orifices, with particular focus on instantaneous and time-averaged velocity distributions, streamline patterns, turbulent kinetic energy, Reynolds shear stress, and out-of-plane vorticity. Results show that, with increasing τ / d , the location of the vena contracta moves closer to the orifice plate, and eventually inside for τ / d > 0.55. Increasing τ / d also results in decreasing turbulent kinetic energy and Reynolds shear stress. For the selected τ / d range, experimental and numerical results are in good agreement with the thick and thin orifice classification available in the literature. • Effect of orifice thickness-to-diameter ratio, τ/ d on flow structures is studied. • Quantitative visualization of details of the orifice flow characteristics of hydrodynamics is reported. • As orifice thickness-to-diameter ratioincreases, decreasing velocity gradients and turbulence intensity are observed. • The minimum pressure downstream of the orifice is increased with increasing τ/ d , reached a peak value at τ/ d = 0.55 [ABSTRACT FROM AUTHOR]

Several challenges exist in the analysis of the sodium-cooled fast reactor (SFR) core using computational fluid dynamics (CFD)codes. These include the intricate task of geometric modeling and mesh partitioning and the substantial computational resources required by CFD calculations. These challenges have been shown to create significant impediments to the practical analysis of the SFR core. This paper proposes a CFD scheme called the Parameterized Modeling and Automated Distributed Computing Approach (PM-ADC) to address the challenges. This approach includes a fuel assembly model tailored for the fast reactor core and incorporates parameterized geometric modeling coupled with a system to automate the distribution of parallel computing. The PM-ADC scheme is divided into two critical components: rapid preprocessing design and the generation of geometric models and meshes for core assemblies, enabled by Parameterized Modeling (PM). In contrast, the Automatic Distributed Computing (ADC) component is responsible for the enhancement of computing efficiency and resource utilization. This is achieved by the automatic allocation and distribution of CFD computing resources within a partitioned domain, resulting in the completion of CFD analyses for all fuel assemblies at full height in a significantly reduced timeframe. The performance of the PM-ADC scheme is analyzed on CFD calculations on representative areas of 81 fuel assemblies within the core of the Chinese Experimental Fast Reactor (CEFR). The results show that the PM-ADC scheme can accurately and efficiently simulate the flow and heat transfer characteristics of the CEFR fuel assembly, demonstrating its potential for high-fidelity analysis of large engineering systems. The study's findings also provide new insights and tools for the ongoing development and analysis of SFRs, contributing to the evolution of nuclear reactor design and safety. [ABSTRACT FROM AUTHOR]