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Study on the Migration Mechanism of Temporary Plugging Agent in Artificial Fractures of Deep Geothermal Reservoirs Based on the Euler-Euler Multiphase Flow Model
Full text linkThe successful use of temporary plugging diverting fracturing technology requires an understanding of the migration and plugging processes of temporary plugging agents into artificial fractures under high temperature settings. In this study, a multiphase flow model for the migration of temporary plugging agents in artificial fractures was developed using the Euler-Euler framework, and numerical simulations were conducted at elevated temperatures. Various factors, including plugging agent injection velocity, concentration, carrying fluid viscosity, wall temperature, and fracture width, were systematically analyzed to assess their impact on the agent’s migration behavior. Detailed analyses, using cloud diagrams of particle volume fraction, velocity, and turbulence intensity, clarified the underlying mechanisms influencing the migration process. The results indicate that as the injection velocity increases, the height of blockages near the wellbore decreases, while the blockage length initially increases before declining. Increasing the concentration of the plugging agent leads to a rise in blockage height and a shift in the front edge toward the injection point. Enhancing the viscosity of the carrying fluid enables the plugging agent to migrate deeper into the fracture, improving deep plugging effectiveness. While changes in wall temperature have limited impact on blockage morphology, temperatures exceeding the critical threshold of 573K significantly intensify particle migration. Moreover, increasing fracture width enhances both the height and length of blockages, with the optimal plugging effect observed when the plugging agent diameter is approximately one-third of the fracture width
Comparative Analysis of Space Efficiency in Contemporary Tall Buildings: Residential, Office, Hotel and Mixed-Use Functions
Full text linkThis paper offers an in-depth comparative analysis of space efficiency in contemporary tall towers, specifically focusing on residential, office, hotel and mixed-use functions (166 cases in total). To the best of current knowledge, no study in the existing literature has focused on this critical and topical subject. The findings underscore the pivotal importance of central core planning and prismatic building forms, which emerge as crucial design elements for optimizing space efficiency across all building types. Central core planning ensures the strategic placement of essential elements like elevators and stairwells, thereby minimizing wasted space and maximizing usable floor area. Meanwhile, prismatic building forms, characterized by their straightforward geometric shapes, facilitate more efficient construction processes and space usage. Average space efficiencies of residential, office, hotel and mixed towers were 76%, 71%, 81%, and 71%, whereas core area to GFA ratio were 19%, 26%, 16% and 26%, respectively. Values fluctuated from the lowest of 55% and 4% to the highest of 94% and 38%. By exploring these dimensions, this research offers valuable insights for the architects and developers, guiding them in the creation of tall buildings that are not only architecturally impressive but also economically viable and highly efficient. This comprehensive analysis serves as a critical resource, emphasizing the need for a balanced approach that considers core planning, structural integrity, and material choice in the design and construction of tall edifices. This holistic perspective is essential for professionals aiming to achieve the highest standards of efficiency and practicality in their architectural endeavors
Evaluation of Thermal Environments in Central Urban Areas (CUAs): Analysis of Existing Focuses and Directions for Future Investigation
Full text linkCentral urban areas (CUAs) are particularly vulnerable to rapid environmental changes and contemporary emerging climatic threats, given their complexity of spatial patterns and intensity of human activities. Typically, CUAs exhibit high-density and heterogeneous morphological characteristics through the combination and interaction of various building blocks constructed across multiple ages, showcasing socio-cultural inheritance and ecological-environmental diversity. The scarcity of open spaces and the dense clustering of buildings in these CUAs impede outdoor thermal comfort and ventilation, reducing residents’ opportunities to conduct outdoor activities during extreme weather conditions. Given these circumstances, it is crucial to conduct systematic evaluations of thermal environmental performance in CUAs. Despite widespread global discussion on this topic, conflicting investigation results persist due to the variations in the observation spatial scales, research techniques, analytical approaches, evaluation indices, and socio-geographical contexts. Focusing on the relationships between urban morphological characteristics and outdoor thermal environmental performance, this paper provides an overview of existing related studies across multiple spatial scales and analyses the advantages and shortcomings of prevalent research techniques. The paper aims to outline a systematic framework for investigating the thermal environments in CUAs facing complex social situations and climatic challenges. The paper suggests that integrating both top-down and bottom-up perspectives is important for evaluating thermal environments in CUAs, while a multi-scale investigation should be conducted to identify the essential issues and the underlying mechanisms across various spatial scales. By adding insights from CUAs, the paper seeks to propose suggestions for future improvements in the domain of urban environmental evaluation
An Investigation of Ag/NaTi2(PO4)3 Seawater Battery Toward Scalable Energy Storage
Full text linkThe seawater battery, consisted of silver (+ve) and carbon-coated NaTi2(PO4)3 (-ve), is an eco-friendly energy storage system due to the low cost and natural abundance of seawater. However, more efforts are still needed to research on the potential issues associated with the ion transport, the breakdown of voltage losses and the attempts for scaling up of such a battery system. Herein, it is found that a nonnegligible shuttle effect of Ag+ ions could pose a serious impact on the reversibility of the battery system. In addition, through the four-electrode measurement, the carbon-coated NaTi2(PO4)3 negative electrode with intercalation/ deintercalation chemistry is identified as the limiting component in the current battery device. Moreover, attempts on applying semi-solid electrolytes to such a battery system are also conducted. It is found that the capacity fading is serious probably due to the hydrogen evolution side reaction at the negative side. Future technical advancements in the key materials and reactor design will make this battery technology more competitive. This work offers important insights to develop safer and scalable seawater batteries
Antisolvent Crystallization (ASC) in Aqueous System: Fundamentals, Sustainability Aspects, and Applications
Full text linkThe present perspective focuses on fundamental and applied attributes of antisolvent crystallization (ASC) in aqueous systems and establishes its potential for various industrial applications. In the ASC method, supersaturation is attained by adding a secondary solvent (antisolvent) to a solution leading to the crystallization of the solute. ASC offers the advantages of increasing yields, and conserving energy over the conventional evaporative or cooling crystallization, and thus appears to be a growing industrially important and sustainable process. The insights on the role of phase equilibrium thermodynamics and kinetics in controlling the crystallization process and crystal properties during ASC are discussed. The choice of solvents is a critical factor in ASC, and the solvent type, properties, and selection are considered briefly. The evaluation of the sustainability aspect of ASC by assessing the environmental benignity of solvents, the impact of their life cycles on the ecology, and associated economic costs are presented. A comprehensive list of solvents used for ASC and their usage pattern is also included. Successively reintegrating ASC into process design and developing different process configurations (stand-alone and hybrid) are reviewed. Finally, the paper highlights the opportunity for more widespread application of ASC in the fields of salt extraction, water treatment, hydrometallurgy, bioprocessing, and the pharmaceutical industry
Seismic Background Noise Level and Station Detectability in the Flores Sea
Full text linkThe Flores back-arc thrust fissure is a significant contributor to earthquake events in the Flores Sea region, as evidenced by seismic investigations. As part of the endeavor to mitigate earthquake risk, seismic data investigations are necessary due to the high potential for earthquakes in the Flores Sea. Background noise in earthquakes is the term used to describe the micro vibrations that are perpetually produced as a result of natural phenomena, such as ocean waves, wind, or human activities. It is crucial to investigate this cacophony in seismology in order to distinguish the primary earthquake signal. Its spectrum analysis can assist in the identification of land changes and the prediction of tectonic activity. This analysis was conducted by employing the Incorporated Research Institutions for Seismology (IRIS) client function as a fetch data tool and the Modular Utility for Statistical Knowledge Gathering Data browser as a data quality monitoring system to verify the health and reliability of seismic data. The three station sites closest to the Flores Sea are the focus of this research data examination. The study's findings indicate that the recorded data at the station is still dominated by cultural noise, as evidenced by the analysis of the probability density function, power spectral density, and noise spectrograms. Additionally, each station exhibits activity with degrees of probability noise that are both high and variable. These results highlight the need for advanced techniques to filter cultural noise and improve the accuracy of seismic signal interpretation in this region. This analysis contributes to understanding tectonic activity in the Flores Sea and underscores the importance of continuous monitoring for earthquake preparedness and risk reduction
An Assessment Tool for Energy Audit of Buildings in Jordan Using Simulation
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In developed nations, there's a growing concern for sustainable energy management, particularly regarding enhancing energy efficiency in both existing and new buildings. The methodology presented considers the energy modelling and simulation of manufacturing buildings through thermal and electrical loads calculations using Dymola/Modelica software. The thermal model is built with the primary components of Dymola along with available models to calculate the heating and cooling loads, whereas the electrical model was calculated using consumption patterns, then the total model was validated against real measurements where the error percentage was 9.96 %. The yearly heating load baseline was 6295 kWh/y and for cooling 46276 kWh/y., the exciting potential for energy- savings and load flexibility, and some suggestions for improving consumption were pointed out and identified. It found that the highest influence on the thermal load reduction was using the double glaze with shading with 61% of the energy-saving options, then replacing the fluorescent with LED with 30%, and finally, the roof insulation was the least influence with 9.5%. For the total consumption, the highest percentage was for replacing the fluorescent with LED with 78% of energy-saving options, then double glaze with shading, and finally the lowest is for the roof insulation
Evaluation and Promotion of Multipurpose Tree Planting in Selected Agroforestry Systems: The Case of Smallholder Farmers in Bore District, Southern Ethiopia
Full text linkThe study was conducted in the Bore district of Guji zone, Southern Ethiopia. The objective of the study was to evaluate and promote multipurpose tree planting under smallholder farmers' of selected agroforestry systems. In this study, four multipurpose trees such as Acacia saligna, Chamaecytisus palmensis, Grevilia robusta, and Pinus patula were evaluated and promoted in home gardens, on farms, and boundary planting agroforestry systems. The growth performance results of the multipurpose trees in selected agroforestry systems showed that the survival rate of the trees was higher in home gardens followed by on-farm and boundary planting agroforestry systems. Moreover, the highest diameter at breast height and tree height growth performances were also recorded in home gardens, on farms, and boundary planting agroforestry systems respectively. Smallholder farmers used different management practices for multipurpose trees planted in selected agroforestry systems. Accordingly, farmers used pruning, hoeing, animal dung, weeding, and fencing management practices for better growth performance of the trees and to minimize the shade effect of the trees on understorey crops. Farmers' preferences for the evaluated and promoted multipurpose trees showed that Pinus patula, Grevilia robusta, Chamaecytisus palmensis, and Acacia saligna were ranked 1st, 2nd, 3rd, and 4th respectively. The feedback from farmers showed that they were willing to plant different multipurpose trees if they could be encouraged and supported with planting materials and technical support. Therefore, government and non-government organizations could be involved in developing agroforestry systems, by providing good planting materials and supporting smallholder farmers' through research and strong extension services
Coastal Erosion Pattern and Rehabilitation of Climate Displaced Communities of 3 Coastal Islands in and Around the South-Eastern Coast of Bangladesh
Full text linkClimate-induced displacement has evolved into a major global issue in recent years. Bangladesh experiences many forms of migration and human movement, which directly and indirectly impact national policies. In this book chapter, the authors explored the trend of coastal erosion and displacement of the communities of 3 coastal islands of the South-Eastern Coast of Bangladesh. Assessing the spatial dynamics of the coastal system requires looking back at the past development and temporal morpho-dynamics of shoreline position and shape. The current study set out to assess the potency of various statistical methods for forecasting shoreline changes and their dynamic nature. In this case, the vulnerability to coastal erosion was quantified using GIS and Remote Sensing. The authors examined how much the land area of Sandwip and Kutubdia islands has shrunk over the last 40 years (1957 to 2018), at rates of 0.822 and 0.242 times respectively. The neighbouring island, Maheskhali, is likewise experiencing coastline erosion, however satellite images show that the island's land area is growing 1.174 times every year. This is taking place as a result of new char land being formed at various points on the Maheskhali island, which has also eroded into the sea at various points. Even when the wind's direction changed and occurred at almost the same maximum values, the erosion scenario at Maheskhali, Sandwip, and Kutubdia remained unchanged. As a result, it may be concluded that Bangladesh's coastal erosion is relatively unaffected by wind speeds, despite fluctuations in wind direction. The authors explored that the rehabilitation of climate-displaced people is very limited compared to the large numbers of people displaced from the coastal islands. Besides, after the displacement, people lose their harmony, identity, and livelihood opportunities after migrating to? New places that are far from the origin. The authors found that if the community-based relocation program is introduced in the living places in the same areas for displaced people around the community living places, that will be most effective
Process Simulation of Wet Flue Gas Desulfurization
Full text linkDuring combustion in power plants, sulfur in coal forms SO2, a key air pollutant causing acid rain. Denitrification of SO2 in exhaust gases is crucial, and simulation is a practical research approach. This article applies Aspen Plus software to simulate and optimize the limestone-gypsum wet flue gas desulfurization process. The results show that the established model can effectively reduce SO2 content, achieving a desulfurization rate of 95.9%, which verifies the feasibility of the process flow. Through sensitivity analysis and orthogonal experiments, it is found that the inlet temperature of flue gas, calcium-sulfur ratio, and water content in limestone slurry are the key factors affecting the desulfurization efficiency. The optimal operating parameter combination is an inlet temperature of flue gas of 80°C, a calcium-sulfur ratio of 1.03, and water content in limestone slurry of 35 kmol/hr, with the calcium-sulfur ratio having the most significant impact on desulfurization efficiency. The study indicates that the combination of this software and the process has good application prospects