Search Results (136)

With growing global energy demand, deep and ultra-deep wells have become a focal point in oil and gas development. Wellbore temperature variations significantly impact drilling and completion operations in such wells. To analyze the temperature distribution in ultra-deep wellbores, a numerical model based on the Gauss–Seidel iterative algorithm was developed. This model explicitly accounts for the convective heat transfer coefficient and the distinct thermophysical properties of drilling fluids in both the drill string and the annulus. By employing adaptive meshing, it significantly enhances computational efficiency while ensuring accuracy. This study investigated the influence of key parameters—including drilling fluid density, specific heat capacity, drill pipe thermal conductivity, and formation properties—on bottom-hole temperature. The results show that the average deviation between the actual wellbore temperature and the model-predicted temperature is 0.5%. The heat transfer dynamics model for ultra-deep wells is validated by the close agreement between theoretical predictions and field data. This study offers a valuable theoretical basis for wellbore temperature management and the control of drilling fluid cooling systems, supporting safer and more efficient development of ultra-deep resources. Full article

Effects of forced aeration on sweet potato growth and yield by decreasing CO₂ concentrations in the rooting zone were investigated. The following four experiments were conducted with forced aeration in the rooting zone of sweet potato: (1) with air containing different CO₂ concentrations to clarify the effects of CO₂ in the rooting zone on the net photosynthetic rate and leaf conductance, (2) with atmospheric air into cultivating soil ridges through porous pipes as a feasibility study, (3) with varying forced-aeration rates, and (4) with varying time intervals of forced aeration to find a more efficient aeration method. The results are summarized as follows: (1) During the six-week growing period, the mean values of net photosynthetic rates and leaf conductance for 1% CO₂ and 2% CO₂ were 0.8 and 0.7 times, respectively, those in the Control with 0.04% CO₂. (2) When the aeration rate was 1.5 L min⁻¹ per 1 m of ridge length, the CO₂ concentration reduced to 0.1–0.2% in the rooting zone, whereas the control ridge with non-forced aeration was 0.5–1.4% CO₂. The fresh and dry weight yields of sweet potato tubers were 1.18 and 1.19 times those of the control, respectively. (3) The CO₂ concentrations decreased as the aeration rate increased. The dry weights of tuberous roots in forced-aeration ridges at aeration rates of 1.25 and 2.5 L min⁻¹ were 1.19 and 1.26 times those in the control, respectively. Sweet potato growth was promoted when forced aeration reduced CO₂ in the rooting zone. (4) The yield increased by 24% even when forced aeration was performed for just 15 min per day after irrigation. In conclusion, reducing rooting zone CO₂ concentrations through forced aeration, even for 15 minutes daily, improves sweet potato yield by approximately 20%. Full article

The quality of water supplied to consumers through drinking water distribution networks is a matter of growing concern and is subject to increasingly stringent new regulations. The utilization of simulation models, which encompass the movement of water through pipes and storage tanks, has been demonstrated to provide valuable information with regard to the improvement of the system operation. However, once a calibrated quality model is available, justifying the evolution of the quality provided by the model at any junction in the network is not direct; however, this is sometimes necessary to carry out the appropriate interventions to improve quality parameters. A methodology to help the comprehension of the quality results provided by simulation models has been developed in this paper. This methodology is based on the principles of event-based transport methods, whereby the quality of a particle is tracked as it moves downstream from a starting point or upstream from an arrival point. Upon reaching a junction, an event occurs that determines the subsequent trajectory of the particle. The details of the method and its potential are demonstrated through an illustrative example, reinforced by its application in a more realistic case. Consequently, by monitoring the particles, it becomes feasible to interpret the quality values obtained at any junction in the network and at any designated moment. If the quality value were the result of a measurement, the method would also allow us to track the origin of that value; in this way, it could be used in the future to locate the possible source of a detected contaminant. Full article

This study investigates the performance of unit-element heat exchangers. Particularly, it focuses on the characteristics of the local air temperature profiles and heat transfer performance of serpentine copper pipe heat exchangers with different diameters, aiming to identify an effective configuration for greenhouse crop cultivation. The term local air temperature refers to the air temperature near the cultivational crops. Cooling experiments were carried out using serpentine heat exchangers with outer pipe diameters of 12.7 mm and 15.88 mm under varying inlet fluid temperatures (−5 °C to 10 °C) and fluid flow rates (0.3–3.0 L/min). Measurements included local air temperature, inlet and outlet fluid temperatures, pipe surface temperatures, and pressure drop, while relative humidity was monitored by checking water condensation on pipe surfaces. The results showed that the average reduction in local air temperature in the area below the heat exchangers reached up to 9.0 °C for the 12.7 mm diameter pipe and 10 °C for the 15.88 mm diameter pipe. Moreover, the pressure drop with the 15.88 mm exchanger was about half that of the 12.7 mm exchanger. These findings highlight the advantages and disadvantages of each type of heat exchanger. Furthermore, they will be useful in selecting an appropriate heat exchanger for greenhouse farming. Full article

To meet the growing requirements of agricultural mechanization, a newly designed 9.5 m span frame has been introduced to replace the traditional 8.0 m span frame, which is constrained by limited internal space. However, as the structural dimensions increase, the failure mechanisms of arch frames under wind loads remain insufficiently understood. In particular, the influences of crop loads, initial geometric imperfections, pipe cross-sectional properties, and cable reinforcement on these failure mechanisms have not yet been systematically investigated. This study aims to reveal the mechanical mechanisms governing the wind-bearing capacity of standard 8.0 m span and newly designed 9.5 m span frames through comparative analysis, and to further investigate how crop loads, initial geometric imperfections, pipe cross-sectional properties, and cable reinforcement modify these mechanisms. The load combinations considered included the following: (1) permanent load + wind load and (2) permanent load + crop load + wind load. The crop load was applied to the frames via a 5-point hanging system. Simulation results indicate that the 9.5 m span frame exhibits a lower allowable wind speed (v_a) than the 8.0 m span frame due to strength failure. Further analysis reveals that the failure is governed by decreased stiffness resulting from the dimensional expansion. Notably, crop loads and initial geometric imperfections were found to amplify second-order bending moments, thereby further decreasing v_a. Moreover, a positive linear correlation is observed between the section modulus of pipes and v_a. However, replacing the circular pipe with rectangular, oval, or elliptical pipes of a similar cross-sectional area does not increase the v_a of the 9.5 m span frame. Conversely, reinforcing the 9.5 m span frame with cables provides strong lateral constraints and effectively suppresses the amplification of bending moments arising from crop loads and initial geometric imperfections. Thus, limiting lateral displacement through reinforcement measures can markedly increase the wind-bearing capacity of frames. The reinforced 9.5 m span frame proves to be a viable replacement for the 8.0 m span frame, meeting the modern demands of facility agriculture in Southern China. Full article

To investigate the mechanism of road collapse induced by structural defects in underground drainage/sewerage pipelines in water-rich sands, laboratory physical model tests were conducted to reproduce the macroscopic development of surface subsidence. A computational fluid dynamics-discrete element method (CFD-DEM) model was then established and validated against the tests to assess its reliability. Using the validated model, we examined the effects of defect size and groundwater level on the progression of groundwater-ingress-driven internal erosion and tracked the evolution of vertical stress and intergranular contacts around the pipe. Results show that internal erosion proceeds through three stages—initial erosion, slow settlement, and collapse—culminating in an inverted-cone collapse pit. After leakage onset, the vertical stress in the surrounding soil exhibits a short-lived surge followed by a decline on both sides above the pipe. The number of intergranular contacts decreases markedly; erosion propagates preferentially in the horizontal direction, where the reduction in contacts is most pronounced. Within the explored range, higher groundwater levels and larger defects accelerate surface settlement and yield deeper and wider collapse pits. Meanwhile, soil anisotropy strengthens with increasing groundwater level but peaks and then slightly relaxes as defect size grows. These qualitative findings improve understanding of the leakage-induced failure mechanism of buried pipelines and offer references for discussions on monitoring, early warning, and risk awareness of road collapses. Full article

Industry 5.0 represents the next stage in the industrial evolution, with a growing impact in the shipbuilding sector. In response to its challenges, Navantia, a leading international player in the field, is transforming its shipyards towards the creation of a Shipyard 5.0 through the implementation of digital technologies that enable human-centered, resilient and sustainable processes. This approach gives rise to Cognitive Cyber-Physical Systems (CCPS) in which the system can learn and where the generated data are integrated into a digital platform that supports operators in decision-making. In this scenario, different smart elements (e.g., IoT-based tows, trucks) are used to transport key components of a ship like pipes or steel plates, which are present in a large number, representing a strategic opportunity to enhance traceability in shipbuilding operations. The accurate tracking of these elements, from manufacturing to assembly, helps to improve operational efficiency and enhances safety within the shipyard environment. Considering the previous context, this paper describes a CCPS that enables tracking and real-time data visualization through portable interfaces adapted to the shipyard operator needs. Following the Industry 5.0 foundations, the presented solution is focused in providing human-centric interfaces, tackling issues like information overload, poor visual organization and accessibility of the control panels. Thus, to address such issues, an iterative human-centered redesign process was performed. This approach incorporated hands-on testing with operators at each development stage and implemented specific adjustments to improve interface clarity and reaction speed. Full article

Thermoset composites are a fast-growing waste stream that resists conventional reusing routes. Water is the principal ageing agent for epoxy-based thermoset materials that bind high-pressure piping, wind-turbine blades and aircraft skins, yet its action is deceptively complex: a rapid, reversible plasticisation is often followed by a far slower, irreversible chemical hydrolysis. Here we bridge that gap to access a reliable diagnosis inspection. Gravimetric immersion tests (from 8 to 93 °C, up to more than a year) and in situ FTIR spectroscopy were performed on four industrial DGEBA networks (two amine-cured matrices and two anhydride-cured matrices that hydrolyse). This 2 + 2 design isolates reversible from irreversible changes and exposes the individual signatures of diffusion, specific sorption and bond scission. The data are rationalised with a compact three-contribution model that superposes Fickian diffusion through nano-voids, adsorption site saturation through hydrogen bonds and a power-law hydrolysis term sharing global Arrhenius parameters. Since the parameters retain clear physical meaning, the approach can be extrapolated to service temperatures, providing a fast, transparent tool for lifetime prediction and for separating recoverable plasticisation from permanent chemical degradation in critical epoxy infrastructure. Full article

Urban water utilities in rapidly developing regions face growing challenges in ensuring continuous supply. Intermittent public water supply leads to unreliable and inequitable access, compelling households to adopt energy-intensive coping strategies. This creates a nexus between water and energy demand at the household level. Few econometric analyses of household water demand have explicitly addressed this demand-side nexus in developing regions. Using survey data from the city of Pimpri-Chinchwad, India, where intermittent water supply is prevalent, we analyze household expenditures related to water access and estimate a piped water demand function with a Discrete-Continuous Choice model. We find that electricity expenditures for accessing water exceed water bills for approximately one-third of households. Including these costs in affordability calculations reveals hidden financial burdens, particularly for middle-income households. Water and electricity prices, income, and household size significantly influence water demand, with an income elasticity of 0.177 and water price elasticities ranging from 0 to −0.876. The cross-price elasticity of −0.097 indicates weak complementarity between electricity and piped water, suggesting electricity price changes do affect water use but are insufficient to drive substantial behavioral shifts. Targeted price increases in high-consumption blocks are more effective at curbing overuse, while simultaneous increases in water and electricity prices may heighten household vulnerability. These findings highlight the need for integrated, nexus-aware demand management strategies, particularly in regions with intermittent supply. Full article

Rapid urbanization and frequent extreme events have made urban flooding a growing threat to residents. This issue is acute in old urban districts, where extremely limited land resources, outdated standards and poor infrastructure have led to inadequate drainage and uneven pipe settlement, heightening flood risk. This study applies InfoWorks ICM Ultimate (version 21.0.284) to simulate flooding in a typical old urban district for six return periods. A risk assessment was carried out, flood causes were analyzed, and mitigation strategies were evaluated to reduce inundation and cost. Results show that all combined schemes outperform single-measure solutions. Among them, the green roof combined with pipe optimization scheme eliminated high-risk and medium-risk areas, while reducing low-risk areas by over 78.23%. It also lowered the ponding depth at key waterlogging points by 70%, significantly improving the flood risk profile. The permeable pavement combined with pipe optimization scheme achieved similar results, reducing low-risk areas by 77.42% and completely eliminating ponding at key locations, although at a 50.8% higher cost. This study underscores the unique contribution of cost-considered gray-green infrastructure retrofitting in old urban areas characterized by land scarcity and aging pipeline networks. It provides a quantitative basis and optimization strategies for refined modeling and multi-strategy management of urban waterlogging in such regions, offering valuable references for other cities facing similar challenges. The findings hold significant implications for urban flood control planning and hydrological research, serving as an important resource for urban planners engaged in flood risk management and researchers in urban hydrology and stormwater management. Full article

Mining, mineral processing, and power generation are just a few of the industries that have made extensive use of pneumatic conveying systems in recent years. The market for pneumatic conveying is anticipated to grow to a value of $30 billion by 2025. However, problems with the pneumatic conveying process are common and include coal particle damage, pipe wall wear, and excessive system energy consumption. A new systematic framework for decision-making is created by combining the Theory of Inventive Problem Solving (TRIZ) with the Decision-Making Trial and Evaluation Laboratory (DEMATEL). This methodology employs TRIZ-Ishikawa to determine the underlying causes of issues from six different perspectives. It then suggests remedies based on TRIZ technical contradictions and uses DEMATEL to examine how the solutions interact to determine the best course of action. This study confirms the viability of this approach in recognizing fundamental contradictions, producing workable solutions, and reaching scientific conclusions in challenging issues by using instances such as wear and tear, obstructions, and low conveying efficiency in pneumatic conveying system elbows. It offers particular references for real engineering projects and suggests practical solutions like employing quick-release flanges and installing multiple sets of airflow regulators. Full article

Wellbore stability is a crucial factor affecting the safe exploitation of offshore natural gas hydrates. As a sustainable energy source, natural gas hydrate has significant reserves, high energy density, and low environmental impact, making it an important candidate for alternative energy. Although research on the stability of screen pipes during horizontal-well hydrate production is currently limited, its importance in sustainable energy extraction is growing. This study therefore considers the effects of hydrate phase change, gas–water seepage, energy and mass exchange, reservoir deformation, and screen pipe influence and develops a coupled thermal–fluid–solid–chemical field model for horizontal-well natural gas hydrate production. The model results were validated using experimental data and standard test cases from the literature. The results obtained by applying this model in COMSOL Multiphysics 6.1 showed that the errors in all simulations were less than 2%, with errors of 12% and 6% observed at effective stresses of 0.5 MPa and 3 MPa, respectively. The simulation results indicate that the presence of the screen pipe in the hydrate reservoir exerts little effect on the decomposition of gas hydrates, but it effectively mitigates stress concentration in the near-wellbore region, redistributing the effective stress and significantly reducing the instability risk of the hydrate reservoir. Furthermore, the distribution of mechanical parameters around the screen pipe is uneven, with maximum values of equivalent Mises stress, volumetric strain, and displacement generally occurring on the inner side of the screen pipe in the horizontal crustal stress direction, making plastic instability most likely to occur in this area. With other basic parameters held constant, the maximum equivalent Mises stress and the instability area within the screen increase with the rise in the production pressure drop and wellbore size, and the decrease in screen pipe thickness. The results of this study lay the foundation for wellbore instability control in the production of offshore natural gas hydrates via depressurization. The study provides new insights into sustainable energy extraction, as improving wellbore stability during the extraction process can enhance resource utilization, reduce environmental impact, and promote sustainable development in energy exploitation. Full article

Resource efficiency is essential in today’s approach to horticulture. The global problems of water scarcity, soil pollution, biodiversity loss, and rapid growth of the global population require increased food production with fewer resources. Resource efficiency is an indicator that allows defining how much biomass an agri-food system can produce per unit of the resource used. Closed hydroponic systems, such as vertical hydroponic towers (VHTs), exhibit high resource efficiency. In these systems, the water use efficiency (WUE) and the nutrient use efficiency (NUE) can be calculated in terms of the water loss through transpiration and the ion concentration in the nutrient solution. The research aimed to determine the WUE and NUE for chard crops in VHT under greenhouse conditions and to evaluate its feasibility as an urban and peri-urban system for leafy vegetable production. Trials were carried out with chard in the fall 2024 in a tunnel-type greenhouse at the facilities of the Autonomous University of San Luis Potosi. The VHTs were built with a 20 L square lower deposit on which a cylindrical pipeline of 11.5 cm in diameter and 1.6 m in height was vertically placed. Each pipe had 45 growing containers distributed on 15 levels of three containers spaced vertically 9 cm and a density of 25 plants·m⁻². The experimental design was completely randomized with three treatments (75, 100, and 125% of Steiner’s nutrient solution) and three replications. The transpiration (Tr) of the crop (recording weight loss in the deposit) and the shoot fresh weight (SFW) of the plants were measured daily using a scale. An ANOVA and Tukey’s test for mean differentiation were performed with p < 0.05. Significant differences were found between treatments for SFW, WUE and NUE obtaining the best results at 75% of Steiner’s nutrient solution. Results show that WUE increased between 3 and 6 times, and NUE between 3 and 12 times compared to chard grown in soil. These results were equal and even higher than horizontal hydroponic systems or vertical farms. Vertical hydroponic closed towers installed in greenhouses are an optimal horticultural production system with high resources use efficiency. The implementation of VHT is feasible in areas where there is water scarcity or have a high population density. Full article

Growing concerns about the energy crisis and global warming have driven interest in geothermal energy. This paper presents a numerical thermo-hydraulic comparison of spiral ground heat exchangers (SGHEs) in vertical and horizontal configurations. Numerical models were validated against experimental data using ANSYS Fluent 2023 R2. Five spiral pitch values were tested to analyze their impact on heat transfer rate (HTR), pressure drop, and total pipe length. Results showed that decreasing pitch increases HTR but significantly raises pressure drop and pipe length. Higher inlet fluid velocities also increased HTR but led to greater pressure drops. Under all tested conditions, the vertical configuration consistently outperformed the horizontal one, achieving up to 19.3% higher mean HTR. For both configurations, a 10 cm pitch provided the best balance between HTR, pressure drop, and pipe length. Increasing inlet velocity from 0.05 to 0.15 ms⁻¹ increased mean HTR by approximately 30% for both configurations. These findings offer practical guidance for selecting the most appropriate SGHE configuration for specific geothermal applications. Full article

Pipe exits into cryogenic systems, such as an exit of a venting or sensor tube inside a cryogenic storage tank, can affect spontaneously occurring acoustic oscillations, known as Taconis oscillations. The amplitude which such oscillations will reach is dependent on losses at the pipe exit that prevent resonant oscillations from growing without bound. Consequently, being able to accurately determine minor losses at a pipe exit is important in predicting the behavior of these oscillations. Current thermoacoustic modeling of such transitions typically relies on steady-flow minor loss coefficients, which are usually assumed to be constant for a pipe entrance or exit. In this study, numerical simulations are performed for acoustic flow at a pipe exit, with and without a wall adjacent to the exit. The operating fluid is cryogenic hydrogen gas, while the pipe radius (2 and 4 mm), temperature (40 and 80 K), and acoustic velocity amplitudes (varying in the range of 10 m/s to 70 m/s) are variable parameters. The simulation results are compared with one-dimensional acoustic models to determine the behavior of minor losses. Results are also analyzed to find harmonics behavior and a build-up of mean pressure differences. Minor losses decrease to an asymptotic value with increasing Reynolds number, while higher temperatures also reduce minor losses (10% reduction at 80 K versus 40 K). A baffle sharply increases minor losses as the distance to pipe exit decreases. These findings can be used to improve the accuracy of oscillation predictions by reduced-order thermoacoustic models. Full article