Search Results (55)

To prevent marine biofouling in seawater lift pumps, electrolyzed seawater containing Cu²⁺ needs to be injected into the pumps. This study employs Computational Fluid Dynamics (CFD) to simulate the variation in Cu²⁺ injection concentration required to achieve a Cu²⁺ concentration of 3 ppb within a 10 cm range around the pump under different operating conditions, including the installation of baffles and varying seawater flow rates. The simulation results demonstrate that CFD can accurately predict the distribution of Cu2+ concentration in electrolyzed seawater, with the distribution significantly influenced by seawater flow direction, necessitating reference to upstream data. When the lift pumps are idle, the required Cu²⁺ injection concentration increases with rising seawater flow rates, reaching 41.9 μg/L at the maximum flow rate of 1.9 m/s. During alternating pump operation, the required Cu²⁺ injection concentration also increases with the flow rate, significantly affected by the pump’s operational position: lower concentrations are required when the upstream pump is active compared to the downstream pump. Additionally, installing baffles around the pumps effectively mitigates the impact of seawater flow on Cu²⁺ distribution, significantly reducing the required injection concentration. This study provides theoretical and data-driven insights for optimising marine biofouling prevention in seawater lift pumps. Full article

The upstream pumping effect of mechanical face seals has a significant influence on their sealing performance. In order to reveal the effect of deep grooves on upstream pumping effects, an experimental and theoretical analysis is carried out in this study. The main novelty of this paper is to analyze the feasibility of deep grooves in a mechanical seal design from the perspective of cavitation and leakage rate. Firstly, an upstream pumping spiral groove is designed and fabricated, with different groove depths from 2 μm to 90 μm. Then, testing is performed with water as the sealing medium. Finally, the cavitation phenomena are captured, and leakage rates are measured during the experiment. The obtained results show that the groove with a depth of tens of microns can be designed according to the laminar flow hypothesis, and Reynolds equation is still valid to predict the cavitation and leakage rate theoretically. The spiral groove with a depth of tens of microns shows a significant upstream pumping effect. Both the theoretical and experimental analyses show that under certain working conditions, deep grooves can realize the zero-leakage sealing design of liquid, which might provide significant guidance for the sealing design of mechanical face seals to enhance sealing performance. Full article

This paper proposes a supercapacitor-battery hybrid energy storage scheme based on a series-parallel hybrid compensation structure and model predictive control to address the increasingly severe power quality issues in oilfield microgrids. By adopting the series-parallel hybrid structure, the voltage compensation depth can be properly improved. The model predictive control with a current inner loop is employed for current tracking, which enhances the response speed and control performance. Applying the proposed hybrid energy storage system in an oilfield DC microgrid, the fault-ride-through ability of renewable energy generators and the reliable power supply ability for oil pumping unit loads can be improved, the dynamic response characteristics of the system can be enhanced, and the service life of energy storage devices can be extended. This paper elaborates on the series-parallel compensation topology, operational principles, and control methodology of the supercapacitor-battery hybrid energy storage. A MATLAB/Simulink model of the oilfield DC microgrid employing the proposed scheme was established for verification. The results demonstrate that the proposed scheme can effectively isolate voltage sags/swells caused by upstream grid faults, maintaining DC bus voltage fluctuations within ±5%. It achieves peak shaving of oil pumping unit load demand, recovery of reverse power generation, stabilization of photovoltaic output, and reduction of power backflow. This study presents an advanced technical solution for enhancing power supply quality in high-penetration renewable energy microgrids with numerous sensitive and critical loads. Full article

Pluvial flooding in South Jakarta poses significant economic disruptions, requiring efficient mitigation strategies. This study focuses on optimizing mobile pump deployment as a non-structural flood control measure. Despite the use of mobile pumps in flood response, there is limited research on their systematic optimization for pluvial flood mitigation. This study presents a transferable framework for deploying mobile pumps to mitigate pluvial flood risks in urban areas, demonstrated through a case study in South Jakarta, Indonesia. The findings indicate that flood depths of 75 cm have a 20–50% probability of occurrence, and rainfall in South Jakarta follows a distinct hourly distribution, with 56.6% of the rainfall occurring in the first hour and 43.4% in the second. Radar imagery from the BMKG is used here as the main tool for real-time rainfall detection. The optimization framework considers channel capacity, flood frequency, impact severity, accessibility, and operational protocols. Among 29 flood-prone locations analyzed, 8 of them require mobile pump intervention. Seven locations benefit from integration with weather prediction tools and SCADA systems, while three require dedicated operational procedures (SOPs). Simulation results indicate that placing mobile pumps near the upstream section of the flooded area yields the most effective flood reduction. A minimum pump capacity of 0.5 m³/s is recommended for optimal performance. This study demonstrates that strategic mobile pump deployment, coupled with predictive tools, significantly reduces pluvial flood risks in South Jakarta and offers a transferable framework for other urban areas. Full article

In recent years, microphysiological systems (MPS) using microfluidic technology as a new in vitro experimental system have shown promise as an alternative to animal experiments in the development of drugs, especially in the field of drug discovery, and some reports have indicated that MPS experiments have the potential to be a valuable tool to obtain outcomes comparable to those of animal experiments. We have commercialized the Fluid3D-X^®, a double-layer microfluidic chip made of polyethylene terephthalate (PET), under the Japan Agency for Medical Research and Development (AMED) MPS development research project and have applied it to various organ models. When intestinal epithelial cells, Caco-2, were cultured using Fluid3D-X^® and a peristaltic pump, villi-like structures were formed in the microchannels. Still, the degree of formation differed between the upstream and downstream sides. To examine the consideration points regarding the effects of the nutrient and oxygen supply by the chip material and the medium perfusion rate and direction on cells in the widely used double-layer microfluidic chip and to demonstrate the usefulness of a new imaging evaluation method using artificial intelligence technology as an assistive tool for the morphological evaluation of cells, the cell morphology in the channels was quantified and evaluated using the Nikon NIS.ai and microscopic observation. Villi-like structures were predominant upstream of the top channel, independent of the medium perfusion on the bottom channel, and those structures downstream developed with an increased flow rate. Additionally, compared to the Fluid3D-X^®, the chip made of PDMS showed almost uniform villi-like sterilization in the channel. The result indicates that the environment within the microchannels differs because the amount of nutrients and oxygen supply varies depending on the medium’s perfusion and the material of the chips. As the amount of oxygen and nutrients required by different cell types differs, it is necessary to study the optimization of culture conditions according to the characteristics of the cells handled. It was also demonstrated that the AI-based image analysis method is helpful as a quantification method for the differences in cell morphology in the microchannel observed under a microscope. Full article

The energy consumption of data center cooling systems is rapidly increasing, necessitating urgent improvements in cooling system performance. This study investigates a pump-driven two-phase cooling system (PTCS) utilizing a parallel-flow heat exchanger (PFHE) as an evaporator, positioned at the rear of server cabinets. The findings indicate that enhancing the vapor quality at the PFHE outlet improves the overall cooling performance. However, airflow non-uniformity induces premature localized overheating, restricting further increases in vapor quality. For PFHEs operating with a two-phase outlet condition, inlet air temperature non-uniformity has a relatively minor impact on the cooling capacity but significantly affects the drop in pressure. Specifically, higher upstream air temperatures increase the pressure drop by 7%, whereas higher downstream air temperatures reduce it by 7.7%. The implementation of multi-pass configurations effectively mitigates localized overheating caused by airflow non-uniformity, suppresses the decline in cooling capacity, and enhances the operational vapor quality of the cooling system. Full article

Under the dual carbon mission, more and more coal mines will face shutting down in the future and stop treating mine water drainage, which, if it escapes, may cause severe secondary damage to the local groundwater quality. Wudong Coal Mine is a currently active subsurface coal mine in Xinjiang, China, that shows high-salinity characteristics. To forecast and discuss future possible groundwater quality damages and potential solutions, we here introduce a model prediction study on the effects of water pollution by coal mine drainage. The study protocol first involves creating a calibrated 2D groundwater flow model by use of FEFLOW software, then designing several flow and solute transport prediction analyses under changing mine water drainage conditions, different pollution source areas and water treatment pumping wells to discuss future prominent flow and transport behavior, as well as water treatment-affecting factors. It has been shown that mine water drainage plays a critical role in maintaining the mine water solute distribution, as without mine draining, local flow and solute distribution change dramatically, altering the groundwater capture zone, and may change the plume-migrating direction from upstream to downstream. A larger pollution source could produce a higher concentration of pollutants and a larger pollution-coverage area. To reduce pollutant concentrations, mine water treatment pumping wells with higher pumping rates can be applied as a useful remedial measure to effectively prevent the pollutant plume front from reaching the important drinking and irrigation water source of the region, Urumqi River. The results of this study can give important suggestions and decision-making support for authorities focused on water treatment and environmental protection decision-making in the region. Full article

The application of blasting in modern engineering construction is prized for its speed, efficiency, and cost-effectiveness. However, the resultant vibrations can have significant adverse effects on surrounding buildings and residents. The challenge of optimizing blasting procedures to satisfy excavation needs while minimizing vibration impacts is a critical concern in blasting excavation. This research addresses this challenge through the development of a 3D simulation and analysis model for an underground pumped storage power plant in East China, utilizing the LS-DYNA finite element analysis software. To explore the influence of charging structures on rock fragmentation and vibration propagation, three distinct blasting programs were formulated, each featuring varied configurations within the machinery room. The analysis revealed that the adoption of an optimized charging structure can significantly decrease damage to the protective layer by approximately 40%, while also reducing the impact on the upstream and downstream side walls by 27.25% and 12.03%, respectively, without compromising the efficacy of the main blast zone. Moreover, the vibration velocities at the remote measurement point were found to be reduced across multiple directions, indicating effective control of the vibration effects. The post-implementation of the optimized blasting strategy at the site, the assessment of the retained surrounding rock integrity, and the impact on protected structures demonstrated that the proposed solution met satisfactory outcomes. This study underscores the potential of simulation-based optimization in managing vibration risks during blasting operations, offering a valuable tool for engineers and practitioners in the field of underground construction. Full article

The significance of groundwater is largely shaped by the quality of wastewater from industrial, agricultural, and municipal sources. Understanding the controlling factors is essential to prevent the spread of contamination in groundwater. These factors could be divided into physical defenses, such as grouting and slurry walls, and hydrodynamic factors, such as injection and pumping wells. In this study, the groundwater transport model (MT3D) and the flow model (MODFLOW) were used to simulate four scenarios for groundwater protection. The first and second scenarios involve grouting and constructing slurry walls to change their depth, permeability, and thickness. The third and fourth scenarios involve injection and pumping wells changing the rate of flow, screen length, and the number of wells. The results show that increasing the thickness of the grouted soil and increasing the grouting depth help to control the level of contamination. Furthermore, multi-slurry walls upstream or downstream of the contamination source are sufficient for preventing the spread of contaminants. The results also reveal that rising rates of injection or pumping wells allow for minimal contamination propagation. The growing number of wells provided greater control over the injection rather than pumping wells. The variation in the screen length of pumping wells is effective for preventing the propagation of contamination. Full article

Anning Refinery, a large-scale joint venture in southern China, possesses significant potential in regard to polluting local groundwater environments due to its extensive petroleum raw materials. This study aims to mitigate the substantial risks associated with oil spills and prevent consequential groundwater pollution by developing a robust groundwater flow model using the MODFLOW module in GMS software that aligns closely with natural and pumping test conditions. Furthermore, by integrating the MT3DMS model, a groundwater solute transport model is constructed and calibrated using sodium chloride tracer dispersion data. Notably, the wax hydrocracking unit and aviation coal finished product tank area are identified as key pollution sources warranting attention. By considering local constraints such as karst collapse, ground subsidence, and single-well water output capacity, the study introduces a tailored groundwater pollution management model. The research simulates various scenarios of petroleum pollutant migration in groundwater and proposes multi-objective emergency response optimization plans. In Scenario 1, simulations show that petroleum pollutants migrate within the unconfined aquifer and enter the karst aquifer as low-concentration plumes over an extended period. Detection of these plumes in karst water monitoring wells indicates upstream unconfined aquifer contamination at higher concentrations, necessitating immediate activation of the nearest monitoring or emergency wells in both layers. Conversely, in Scenario 2, pollutants reside briefly in the unconfined aquifer before entering the karst aquifer at relatively higher concentrations. Here, low-efficiency pollutant discharge through unconfined aquifer monitoring wells prompts the activation of nearby karst aquifer monitoring or emergency wells for effective pollution control. This model underscores the necessity for proactive monitoring and validates the efficacy of coupled numerical modeling in understanding pollutant behavior, offering valuable insights into pollution control scenario assessments. In summary, the study emphasizes the importance of targeted monitoring and emergency protocols, demonstrating the benefits of integrated modeling approaches in industrial areas prone to pollution risks, and provides critical theoretical and practical guidance for groundwater protection and pollution management, offering transferable insights for similar industrial settings worldwide. Full article

To investigate the hydraulic characteristics during the start-up process of a full-flow pumped storage unit under low-head conditions, numerical simulations were conducted to study the dynamic characteristics during the process, providing a detailed analysis of the dynamic behavior of the internal flow field during the transition period as well as the associated variation in external performance parameters. Study results revealed a vortex-shedding phenomenon during the initial phase of the start-up process. These vortices restrict the flow, initiating a water hammer effect that abruptly elevates the upstream pressure within the runner. As the high-pressure water hammer dissipated, the flow rate rapidly increased, leading to a secondary but relatively weaker water hammer effect, which caused a momentary drop in pressure. This series of events ultimately resulted in significant oscillations in the unit’s head. After the guide vanes stop opening, the vortex structures at the runner inlet and outlet gradually weaken. As the runner torque continues to decline, the unit gradually approaches a no-load condition and enters the S-shaped region. Concurrently, pressure pulsations intensify, and unstable vortex formations reemerge along the leading and trailing edges of the runner blades. The escalated flow velocity at the runner’s exit contributes to the elongation of the vortex band within the draft tube, ultimately configuring a double-layer vortex structure around the central region and the pipe walls. This configuration of vortices precipitates the no-load instability phenomenon experienced by the unit. Full article

An inducer is a key component in a cryogenic pump to improve its cavitation performance. The thermodynamic effects of the cryogenic medium make the cryogenic cavitation flow extremely complicated. For this reason, it is crucial to investigate the cryogenic cavitation flow of the inducer which is equipped upstream of the cryogenic pump. In this paper, the isothermal cavitation model is modified based on the law of heat conduction, and the cryogenic cavitation model of the inducer is developed by considering thermodynamic effects. The turbulence model is also modified to account for the compressibility of cryogenic cavitation flow. The methods of numerical calculations are performed to investigate the influence of thermodynamic effects on cryogenic cavitation of the inducer. The law of the spatio-temporal evolution of cryogen cavitation in the inducer is clarified. The initial position, development and collapse phenomenon of cavitation are obtained. The relationship between the generation and collapse of the cavitation and the work capacity of the inducer’s blade, the relationship between thermodynamic effects and the influence of the inducer’s blade tip leakage vortex and thermodynamic on cryogenic cavitation of the inducer are revealed. Full article

The prediction of water plant flow should establish relationships between upstream and downstream hydrological stations, which is crucial for the early detection of flow anomalies. Long Short-Term Memory Networks (LSTMs) have been widely applied in hydrological time series forecasting. However, due to the highly nonlinear and dynamic nature of hydrological time series, as well as the intertwined coupling of data between multiple hydrological stations, the original LSTM models fail to simultaneously consider the spatiotemporal correlations among input sequences for flow prediction. To address this issue, we propose a novel flow prediction method based on the Spatiotemporal Attention LSTM (STA-LSTM) model. This model, based on an encoder–decoder architecture, integrates spatial attention mechanisms in the encoder to adaptively capture hydrological variables relevant to prediction. The decoder combines temporal attention mechanisms to better propagate gradient information and dynamically discover key encoder hidden states from all time steps within a window. Additionally, we construct an extended dataset, which preprocesses meteorological data with forward filling and rainfall encoding, and combines hydrological data from multiple neighboring pumping stations with external meteorological data to enhance the modeling capability of spatiotemporal relationships. In this paper, the actual production data of pumping stations and water plants along the East-to-West Water Diversion Project are taken as examples to verify the effectiveness of the model. Experimental results demonstrate that our STA-LSTM model can better capture spatiotemporal relationships, yielding improved prediction performance with a mean absolute error (MAE) of 3.57, a root mean square error (RMSE) of 4.61, and a mean absolute percentage error (MAPE) of 0.001. Additionally, our model achieved a 3.96% increase in R² compared to the baseline model. Full article

Artificial lift systems, such as electrical submersible pumps and sucker rod pumps, frequently encounter operational challenges due to high gas–oil ratios, leading to premature tool failure and increased downtime. Effective upstream gas separation is critical to maintain continuous operation. This study aims to predict the efficiency of downhole gas separator using machine learning models trained on data from a centrifugal separator and tested on data from a gravity separator (blind test). A comprehensive experimental setup included a multiphase flow system with horizontal (31 ft. (9.4 m)) and vertical (27 ft. (8.2 m)) sections to facilitate the tests. Seven regression models—multilinear regression, random forest, support vector machine, ridge, lasso, k-nearest neighbor, and XGBoost—were evaluated using performance metrics like RMSE, MAPE, and R-squared. In-depth exploratory data analysis and data preprocessing identified inlet liquid and gas volume flows as key predictors for gas volume flow per minute at the outlet (GVFO). Among the models, random forest was most effective, exhibiting an R-squared of 96% and an RMSE of 112. This model, followed by KNN, showed great promise in accurately predicting gas separation efficiency, aided by rigorous hyperparameter tuning and cross-validation to prevent overfitting. This research offers a robust machine learning workflow for predicting gas separation efficiency across different types of downhole gas separators, providing valuable insights for optimizing the performance of artificial lift systems. Full article

Climate change has resulted in an increase in extreme rainstorm events, posing the challenges of urban waterlogging and runoff pollution. Low Impact Development (LID) is widely used to address the issues above, but its effectiveness is unknown in mountainous areas. Due to a flash flood and high flood peak, storage pumping stations are also needed to drain. Thus, a framework composed of storage pumping stations and Low Impact Developments (LIDs) was proposed based on the topography and the regional upstream and downstream relationships. The water quantity in this framework is applied to YI County in Hebei Province, China. The results showed that individual LIDs effectively reduced runoff volume, with the implementation area being more crucial than the location. Combining storage pumping stations with LIDs significantly reduces peak outflow and delays it by 5 to 51 min. The combined downstream implementation of storage pumping stations and LIDs yielded the most effective results. These findings offer important insights and management strategies for controlling waterlogging in mountainous cities of developing countries. Full article