Curved bladelets on wind turbine blades play an important role in improving the performance and efficiency of wind turbines. Implementing such features on the tip of wind turbine blades can improve their overall aerodynamic characteristics by reducing turbulence and loading without hindering lift generation and overall efficiency, thus leading to increased energy capture and reduced costs over the life of the turbine. Subjecting the integrated blade tip to optimization procedures can maximize its beneficial contribution to the assembly in general. Within this context, a systemic workflow is proposed for the optimization of a curved bladelet implemented on a wind turbine blade. The approach receives input in the form of an initial tip geometry and performs improvements in two distinct stages. Firstly, shape optimization is performed directly on the outer shape to enhance its aerodynamic properties. Subsequently, the topology of its interior structure is refined to decrease its mass whil... [more]

Accurate stress field calculation of the casing-cement-stratum system is crucial for evaluating wellbore integrity. Previous models treated in-situ stress as boundary pressure loads, leading to unrealistic infinite displacements at infinity. This study presents a three-dimensional (3D) analytical solution for the stress field within the casing-cement-stratum system in inclined wells, considering in-situ stress and hydrostatic stress in cement as the initial stress state and taking into account stress components related to the axial direction. Assuming a plane strain condition and superimposing the in-plane plane strain problem, elastic uni-axial stress problem and anti-plane shear problem, a 3D analytical solution is obtained. Comparisons with previous models indicate that the existing model overestimates the absolute values of stress components and failure potential of casing and cement in both 2D and 3D scenarios. The presence of initial stress in cement greatly increases the absolut... [more]

In many process engineering fields, gas-particle fluidized beds are widely used. In fluidized bed research, the discrete element method, or DEM, has been a powerful tool for design and operation purposes. However, with the use of Type-A powders, fluid catalytic cracking or FCC particles being classical cases, they have hardly been reported in DEM simulations of fast fluidization. This study paid close attention to the suitable selection of a stiffness constant and a DEM time step. To reflect their respective effects and complicated interactions, a so-called relative DEM time step was defined. The drag coefficient was correlated using the energy-minimization multi-scale (EMMS) approach to reasonably calculate the gas−solid interaction. Six representative cases with different relative time step values were chosen to simulate a micro-fluidized bed of Type-A FCC powders. The results showed that DEM employing EMMS-based drag force was able to greatly enlarge the suitable range of relative t... [more]

Accurate prediction of the remaining useful life (RUL) of rolling bearings can effectively ensure the safety of complicated machinery and equipment in service. However, the diversity of rolling bearing degradation processes makes it difficult for deep learning-based RUL prediction methods to improve prediction accuracy further and provide generalizability for engineering applications. This study proposed a novelty RUL prediction model for rolling bearings based on a bi-channel hierarchical vision transformer to reduce the impact of the above problems on prediction accuracy improvement. Firstly, hierarchical vision transformer network structures based on different-sized patches were employed to extract depth features containing more degradation processes information from input samples. Second, the dual channel fusion method is implemented into classic RUL prediction networks based on a multi-layer fully connected network to improve prediction accuracy. With two distinct validation exper... [more]

In an axial granular bed filter (GBF), a new mesoscale simulation approach is obtained by combining the macroscopic calculation models, i.e., the equations of the total pressure drop and dust-removal efficiency into the porous media model and the source term of the conservation equations. After grid-dependent tests and experimental validation, the effects of different conditions, i.e., granular bed height L, superficial gas velocity ug, dust diameter dp, dust concentration cp, granular diameter dg, initial bed voidage ε0, and filtration time t, on the pressure drop and dust-removal efficiency are investigated. The results show that the pressure drop is related to the inertial and viscous resistance terms, which increase with increasing L, ug, cp and t and decreasing ε and dg. The dust-removal efficiency is related to the Reynolds number, effective Stokes number, and equivalent granular diameter ratio. It increases with increasing L, ug, dp and t (small values), and decreasing cp, ε, an... [more]

In order to handle the corrosion of underwater production pipe sinks in deepwater oil fields, a non-solid phase silicone plugging agent, an external clamp, and an underwater injection tool are combined in this paper’s innovative pipeline repair technique proposal. The optimal main agent to curing the agent ratio for non-solid phase silicone plugging agents was found to be 100:25, which was achieved through an experimental examination of the curing process. The compressive and cementing strength changes in the curd plugging agent were disclosed by testing and evaluating the mechanical behavior of the plugging agent. In addition, the limits of the compressive and cementing strength were found to be 143 MPa and 11.6 MPa, respectively. Based on this, a computational-fluid-dynamics(CFD)-based analytical approach of the complicated flow field in a deep sea environment on the eroding impact of a plugging agent was developed. Through numerical simulation testing, the mathematical relationship... [more]

An extension of the equilibrium stage model to improve its applicability to reactive distillation is presented. The significant aeration of the liquid holdup on trays leads to the amount of clear liquid present being significantly less than the volume available. Tray hydraulic correlations are incorporated by leveraging the existing inside-out algorithm to rigorously calculate the liquid holdup on distillation trays, turning this parameter into an additional model output and eliminating the need to estimate this parameter beforehand. Application of this extended model shows that the aeration of the liquid holdup cannot be neglected for systems where the reaction kinetics limit the reactive productivity, and leads to column designs where additional reactive trays are needed to provide adequate reactive capacity. The workflow of this model provides a more robust path to obtaining reactive distillation column and tray designs that comply with liquid holdup requirements and tray hydraulic... [more]

Micro-cogeneration with locally produced biogas from waste is a proven technique for supporting the decarbonization process. However, the strongly variable composition of biogas can make its use in internal combustion engines quite challenging. Dual-fuel engines offer advantages over conventional SI and diesel engines, but there are still issues to be addressed, such as the low-load thermodynamic efficiency and nitrogen oxide emissions. In particular, it is highly desirable to reduce NOx directly in the combustion chamber in order to avoid expensive after-treatment systems. This study analyzed the influence of the combustion system, especially the piston bowl geometry and the injector nozzle, on the performance and emissions of a dual-fuel diesel−biogas engine designed for micro-cogeneration (maximum electric power: 50 kW). In detail, four different cylindrical piston bowls characterized by radii of 23, 28, 33 and 38 mm were compared with a conventional omega-shaped diesel bowl. Moreov... [more]

To achieve a balance between supply and demand during cogeneration system operation, it is necessary to improve the peak regulation capacity and regulatory flexibility of the unit. Considering the excellent performance of energy storage systems, a heat-coupled storage system with high- and low-pressure bypass is proposed to increase peak regulation capacity. Employing a 300 MW heating unit as the research object, thermal system models of a traditional-pumping steam-heating system, a high- and low-pressure bypass heating system, and a coupled system were built using Aspen Plus software. The electric heating characteristics of the three systems, as well as the peak regulation capacity and peak regulation depth of the coupled system, were analysed under different storage and heat release loads. Results indicate that the high- and low-voltage bypass system and the coupled system both improve the peak capacity and control flexibility of the unit. Moreover, the coupled system has a greater i... [more]

The recovery of low-temperature steam is of great significance to the effective utilization of energy. Direct contact condensation (DCC) technology is an effective heat recovery method with a low initial investment. An evaluation of the direct contact condensation heat transfer technology of water droplets and low-temperature saturated steam (at an absolute pressure of 7.3−19.9 kPa) was performed using both experimental and computational approaches. In the experiment, an experimental device based on the weighing method was set up, and the direct contact heat transfer process between droplets with a normalized diameter of less than 21.7 and saturated pure steam at 40−60 °C was experimentally investigated. The transient condensation efficiency and heat transfer coefficient were calculated by the real-time mass variation. The rapid condensation stage was classified to discuss the effects of initial droplet diameter, pressure, temperature, and mass flow rate on the heat transfer process. A... [more]

The gas−solid flow of mixed seeds of oat and vetch in the air-blowing venturi tube was simulated numerically by means of a coupling approach of the discrete element method (DEM) and computational fluid dynamics (CFD). In the gas−solid coupling model, EDEM software was used to depict the discrete particle phase, and ANSYS Fluent software was used to describe the continuous gas phase. The effects of the seed entry angle and inlet air velocity on the uniformity of mixed seed supply were studied and analyzed from the angle of airflow field variation and mixed seeds movement characteristics. The simulation results showed that the seeding angle has a great influence on the seed movement in the tube and affects the pressure and velocity gradient of the airflow field. If the seed insertion angle is too large, the number of collisions between the seed and the tube wall will increase, and the phenomenon of seeds retention and disordered jumping will occur. The inlet air velocity mainly affects t... [more]

The conventional fed-batch process characterized by a low titer currently challenges pharmaceutical development. Process optimization by applying a perfusion process in the pre-stage and subsequent production phase at a high seeding density (HSD) can meet this challenge. In this study, we employed a simplified approach based on measured experiments, namely segmented modeling, to systematically analyze an HSD fed-batch process compared to a standard process. A comparison indicated that the metabolic phases of HSD processes are not only shifted in time, but metabolite trends show an altered metabolism. In an extended study, we integrated the intracellular fluxes determined by a metabolic flux analysis into the segmented modeling approach. Compared to using only extracellular rates, similar phases are identified, and this highlights the reliability of phase identification modeling using extracellular rates only. Furthermore, the segmented linear regression approach is used to create a mod... [more]

Industry 4.0 has considerably advanced multiple manufacturing fields through digitalization and intelligentization. Many technologies, such as supervisory control, data acquisition, and data analytics, have been used widely in manufacturing sites to enhance production efficiency. Therefore, this created a cloud-based anomaly detection module for epidemic prevention at the manufacturing site. Image process technologies, deep learning algorithms, and cloud computing were employed in the proposed module to automatically identify labor anomaly behavior in the manufacturing site and prevent the epidemic. This study used image processing technologies and deep learning to recognize and train the manufacturing site image. Accordingly, the analyzed result could be incorporated into the cloud system using the Message Queuing Telemetry Transport (MQTT) protocol. Therefore, the administrators and laborers can be notified regarding the anomaly behavior. The author used the image data obtained from... [more]

To achieve efficient mixing in a Venturi tube mixer (VTM), an optimization with a two-step method for this mixing device based on a Venturi tube (VT) was carried out using numerical simulation. Firstly, the effects of the structural parameters on the flow in VT were revealed, and the optimized configuration was determined for the following VTM. Subsequently, by introducing a jetting tube, the suction capacity, energy consumption and mixing quality were used to evaluate the performance of VTM under various configurations and operating conditions. According to the effects of the structural parameters on the mixing quality of VTM, an empirical formula for mixing quality with structural parameters was proposed. Finally, an optimized VTM was proposed. This work can provide a valid suggestion for the design and optimization of such a mixing device.

Supercritical CO2 (scCO2) is utilized in the supercritical fluid extraction of emulsions (SFEE) to swiftly extract the organic phase (O) from an O/W emulsion. The dissolved substances in the organic phase precipitate into small particles and remain suspended in the water (W) with the aid of a surfactant. The process can be continuously conducted using a packed column in a counter-current flow of the emulsion and scCO2, at moderate pressure (8−10 MPa) and temperature (37−40 °C). To ensure the commercial viability of this technique, the organic solvent must be separated from the CO2 to facilitate the recirculation of both streams within the process while minimizing environmental impact. Thus, the aim of this work was to design a plant to produce submicron materials using SFEE, integrating the recovery of both solvents. First, experimental equilibrium data of the ternary system involved (CO2/ethyl acetate/water) were fitted with a proper thermodynamic model. Then, simulations of the whole... [more]

The global coronavirus pandemic (COVID-19) started in 2020 and is still ongoing today. Among the numerous insights the community has learned from the COVID-19 pandemic is the value of robust healthcare inventory management. The main cause of many casualties around the world is the lack of medical resources for those who need them. To inhibit the spread of COVID-19, it is therefore imperative to simulate the demand for desirable medical goods at the proper time. The estimation of the incidence of infections using the right epidemiological criteria has a significant impact on the number of medical supplies required. Modeling susceptibility, exposure, infection, hospitalization, isolation, and recovery in relation to the COVID-19 pandemic is indeed crucial for the management of healthcare inventories. The goal of this research is to examine the various inventory policies such as reorder point, periodic order, and just-in-time in order to minimize the inventory management cost for medical... [more]

Al−Ni−Er is an essential system in heat-resistant Al alloys. However, the aluminum-rich corner of this system, which has the most practical application significance, has not been fully studied. In this work, the phase equilibria of the Al−Ni−Er system are investigated via experiments and thermodynamic modeling. The isothermal sections of the Al-rich corner of this ternary system at 600 and 700 °C were determined through equilibrated alloys combined with scanning electron microscopy (SEM), electron probe microanalysis (EPMA) and X-ray diffractometry (XRD). In addition, the vertical sections of the Al−Ni−Er system at Al0.7Ni0.3−Al0.7Er0.3 and Al0.8Ni0.2−Al0.8Er0.2 were measured via differential scanning calorimetry (DSC) analysis. A new ternary compound, τ14-Al12Ni2Er3, was discovered. On the basis of the experimental results of this and previous studies, the ternary Al−Ni−Er system was optimized with the calculation of phase diagrams (CALPHAD) method. The calculated isothermal and verti... [more]

The frequency of roof-caving accidents ranks first among all coal mine accidents. However, the scattered knowledge system in this field and the lack of standardization exacerbate the difficulty of analyzing roof fall accidents. This study proposes an ontology-based semantic modeling method for roof fall accidents to share and reuse roof fall knowledge for intelligent decision-making. The crucial concepts of roof fall accidents and the correlations between concepts are summarized by analyzing the roof fall knowledge, providing a standard framework to represent the prior knowledge in this field. Besides, the ontology modeling tool Protégé is used to construct the ontology. As for ontology-based deep information mining and semantic reasoning, semantic rules based on expert experience and data fusion technology are proposed to evaluate mines’ potential risks comprehensively. In addition, the roof-falling rules are formalized based on the Jena syntax to make the ontology uniformly expressed... [more]

Improving the separation efficiency of the layer melt crystallization process is a key but difficult task. Herein, a comprehensive model involving both crystallization and sweating was proposed and used to optimize the operating time of crystallization and sweating processes. The crystallization process was modeled based on the relationship between differential and integral distribution coefficients under a constant layer growth rate. For the sweating process, an empirical sweating equation was employed to govern the sweating model, the parameters of which were determined experimentally using P-xylene as the model substance. The separation efficiency was then optimized by minimizing the operating time at a given product purity and yield. A sensitivity analysis showed that the crystallization and sweating times nonlinearly increase with increasing yield. After the yield exceeds 0.65, an increasing crystallization time is the dominant factor in improving the separation efficiency, while... [more]

Utilization of nuclear research reactors is of high importance for education and training, research and development, and many other applications. However, less effective utilization encountered in research reactors is mainly due to limitations in power levels and related experimental facilities. Such limitations, however, have led different global owners of research reactors to consider upgrading the power levels of their reactors to accommodate the increase in utilization demands. To consider upgrading the power levels of research reactors without replacing major components, a pair of essential analyses must be performed, namely the neutronic evaluation of nuclear fission and thermal-hydraulic evaluation for heat removal from the reactor core. In this work, a conceptual upgrade to the core design and configuration of MSTR, or Missouri University of Science and Technology Reactor (200 kilowatts (kW)), is demonstrated. The conceptual design of the MSTR high-power configuration (MSTR-HPC... [more]

Machine learning has increasingly become the bridge between theoretical knowledge and practical applications, transforming countless aspects of modern life [...]

Semi-empirical fouling models have proven more effective in predicting the fouling behavior of crude oils in heat exchangers. These models have aided refineries in optimizing operating conditions to minimize or eliminate fouling in preheat exchangers. Despite their complexity, the models continue to improve in approximating real behavior by taking into account previously neglected aspects. This paper summarizes these findings from various studies along with highlighting different factors which were considered to enhance the predictability of the models. A critical analysis is presented to emphasize that activation energy in the deposition term varies depending on the physical processes involved and may not conform to the precise definition of activation energy. Two primary modeling approaches for crude oil fouling have emerged, i.e., deterministic and threshold models. Threshold models have gained more attention due to their fewer adjustable parameters. The stability or compatibility o... [more]

The state of interface adhesion, as measured by the void ratio, is a critical factor affecting the adhesion strength and heat dissipation efficiency of a system. However, non-destructive and rapid detection of the adhesion process remains a challenge. In this study, we used all-atom molecular dynamics simulations to investigate the interfacial thermal conductance of silicon and polymer at various adhesion void ratios, with the aim of achieving non-destructive and rapid detection of the adhesion process. Our results demonstrate a linear relationship between the interfacial thermal conductance and effective contact area at different temperatures, enabling the numerical value of interfacial thermal conductance to serve as an indicator of interfacial adhesion state. Furthermore, we also output the surface temperature of the adhesive interface. The non-uniformity of the surface temperature evolution can be used to identify the location of bubbles on the adhesive surface, which further refle... [more]

In order to analyze the inner flow in a multi-stage double-suction centrifugal pump, which is regarded as a common way of knowing the current characteristics of the pump and as the basis of optimization for better performance, a numerical simulation considering the velocity field distribution characteristics and pressure fluctuation propagation law using the detached eddy simulation method was conducted. Additionally, the principle of entropy generation was put to use to quantify and compare the energy loss of different components. The results reveal that the existence of unstable flow structures in the first-stage impeller and a large number of vortical structures in the back-channel result in reduced operational efficiency of the pump. Furthermore, the pressure fluctuation intensity reaches its maximum with 0.15 at the blade trailing edge, which propagates to the tongue region of the forward flow channel and the double-volute under the low rates condition. Additionally, the main freq... [more]

Most bubble breakage models have been developed for multiphase simulations using Euler-Euler (EE) approaches. Commonly, they are linked with population balance models (PBM) and are validated by making use of Reynolds-averaged Navier-Stokes (RANS) turbulence models. The latter, however, may be replaced by alternate approaches such as Large Eddy simulations (LES) that play a pivotal role in current developments based on lattice Boltzmann (LBM) technologies. Consequently, this study investigates the possibility of transferring promising bubble breakage models from the EE framework into Euler-Lagrange (EL) settings aiming to perform LES. Using our own model, it was possible to reproduce similar bubble size distributions (BSDs) for EL and EE simulations. Therefore, the critical Weber (Wecrit) number served as a threshold value for the occurrence of bubble breakage events. Wecrit depended on the bubble daughter size distribution (DSD) and a set minimum time between two consecutive bubble bre... [more]