Avanti Publishers
Not a member yet
711 research outputs found
Sort by
Investigation of Gas-Solid Flows in a Spout Fluidized Bed on Drag and Solid Stress: CFD-DEM, TFM, and Experimental Validation
Get PDFIn this work, experimental and numerical simulation methods are used to study the gas-solid two-phase flow in a three-dimensional rectangular spouted bed. In particular, the TFM and the CFD-DEM simulation results are compared with experimental data of the spouted bed. The influence of different drag models and friction stress models on the applicability of the simulation technology, Gidaspow, BVK, Koch-Hill, and Syamal-O'Brein drag models are investigated, respectively. Besides, the influence of the Syamal (S-R-O) and Srivastava-Sundaresan (S-S) friction stress models considering different transition points on the flow characteristics of particles in a spouted bed is also studied. Experimental verification shows that the Gidaspow drag, and S-S friction stress models are more consistent with experimental results. The fountain height predicted by CFD-DEM is closer to the experiment. It is found that the heterogeneous flow structure resulted in such a phenomenon in that the bubble cap blocked the gas flow pathway and increased the drag coefficient, while the bypass of the gas phase near the walls in the bubble reduced the drag coefficient
Application of Improved Fuzzy-Set Pair Analysis in Mine Water Environmental Quality Evaluation
Get PDFMine water is an important water resource, mine water resource is of great significance to realize the sustainable development of economy and society, and the evaluation of water quality is an important link of mine water resource. This paper will be improved in Nemerow index method is applied to the fuzzy-set pair analysis method of composite algorithm, and the water quality evaluation of Kongzhuang Mine in Xuzhou is carried out. Finally, compared with the evaluation results of set pair analysis method and grey clustering method, it is shown that the evaluation results of this method are reasonable and scientific, which can provide reliable basis for the utilization of mine water resources
Design of Experiment Method – An Application in Improving Quality of Magnesium Hydroxide Produced from Natural Seawater Bittern
Get PDFSeawater bittern is an important resource for production of magnesium hydroxide. It is particularly meaningful for countries of which long beaches and high temperatures are available as natural advantages. This production process bases on the main reaction between solutions containing magnesium and various alkaline agents. Among of precipitants, lime slurry is frequently used as an inexpensive reactant. However, the contamination of calcium in the final magnesium hydroxide is a major problem which limits applicability of this product in many fields required extremely high quality of magnesium hydroxide such as pharmaceuticals, and catalyst, etc. In this work, magnesium hydroxide with more than 99% purity will be recovered from natural seawater bitterns by using the design of experiment (DOE) method. Selected from nine potential factors, a full factorial design considering four main effects was applied to construct a second-order regression model which allows predicting favorable conditions to pursuit high purity of magnesium hydroxide from multi-component seawater bittern and lime milk. On the one hand, the results for a 1.0 L batch investigation proved that factors such as concentration of Ca(OH)2 in lime suspension and residence time have strong negative influences on the product purity, besides positive effects of reaction temperature. On the other hand, magnesium concentration in the bittern was absent in the regression model. At the optimal conditions, the chemical purity of the solid product was obtained at a value of 99.35%. Thus, this product, and therefore its corresponding production conditions, can be recommended for applications required high quality of magnesium hydroxide
Synthesis and Potential Applications of Modified Xanthan Gum
Get PDFDesigning high-performance adsorbents for wastewater treatment and antibacterial materials for food and biomedical applications and excellent drug carrier to prolong time retention of the therapeutic drug based on biodegradable polymers has gained more interest in recent years. Among these materials, xanthan gum, which is a natural polysaccharide and plays a vital role in various applications such as industry, enhanced oil recovery, water-based paints, pharmaceuticals, and personal care products because it has excellent properties such as biodegradability and non-toxicity. On the other hand, it has many affected limitations, including microbially attack, poor thermal and mechanical stability, and low surface area. So, in this review, we focused on the advanced modifications on xanthan gum and their applications in wastewater treatment, protein delivery, and designing antimicrobial materials
Prediction of Road Traffic Noise by CRTN Model in a Sub-Urban Town of India
Get PDFPresent study was undertaken for assessment of spatial characteristics of road traffic noise at varying intervals viz early morning (8-9 am), late morning (11-12 pm), afternoon (2-3 pm) and evening (6-7 pm) time at ten important locations (near school building) of G. T. Road which is passing through the Burdwan town. Digital noise meter was used for recording the traffic noise and noise contour map was constructed by using Geographical Information System (GIS). The recorded data revealed that the highest and lowest average noise 67.1 dB (A) and 86.9 dB (A), respectively. The results revealed that the performance of the CRTN model in both afternoon and evening time for predicting noise level near school building with a coefficient of determination (R2) are 0.536 and 0.544 and a mean difference of - 1.19 dB (A) and - 0.48 dB (A) between the measured and predicted values respectively. Similarly, Pearson statistics also revealed the strong correlation between measured and predicted noise level at afternoon (r = 0.732, p < 0.016) and evening time (r = 0.744, p < 0.014). However, the predicted traffic noise during early morning and late morning hour are less than 0.5. These low values are due to irregular traffic speed, traffic density and irregular building height are the appropriate reasons for low accuracy in predicting model. Finally, it may be suggested that CRTN model can be a decision tool for predicting equivalent noise level in the city like Burdwan
The Influence of Built Environment on Landslides. A Case Study: Converney-Taillepied
Get PDFPermanent deep soil landslides are regular downstream movements over a long period. The soil mass moves along an existing sliding surface, contrary to spontaneous landslides that are quite fast downstream movements, starting after a triggering event.
The present study aims to define the effects and the relevant impact that urbanization can cause on the evolution of an important permanent landslide. It reports existing knowledge and describes the phenomenon and its behavior according to increasing urbanization and geotechnical mechanisms.
The intense urbanization (terraces, building reinforcements due to maintenance needs, surface drainage systems, deep drainage boreholes, infrastructure development) has contributed to stabilizing the landslide as a whole. However, geological and hydrogeological factors and the choice of areas where urban density can become higher are equally crucial for landslide stability.
The Converney-Taillepied landslide upon Belmont-Sur-Lausanne, Paudex, and Lutry (Vaud Canton, Switzerland) has been selected as a case study. Several historical events occurred in those areas when they were only rural, while over the past hundred years, the geography has been deeply modified by urbanization.
Once the overall study of the Converney-Taillepied landslides is finished, this work will focus on the most critical areas resulting from the latter. The project analyzes the present conditions of the phenomenon, its characterizations, and the definition of different scenarios to determinate and analyze the different stability factors. Then it proceeds with the analysis of decisive mechanisms that will be able to affect positively or negatively the landslide condition.
Final results suggest that the presence of the built environment on the landslide after the delicate building phase could have a stabilizing effect
Coexistence and Development Model of Multi-Minerals Dominated by Multilayer Magma Intrusion: A Case Study of Huanghebei Coalfield in North China Basin
Get PDFThe diversity of coal measure determines the occurrence state and spatial distribution complexity of mineral resources. Abundant resources have become an important part of geological resources and have attracted more and more attention. Coal measure and their overlying and underlying strata often coexist with various mineral resource types, and there is a certain relationship between their genesis and occurrence. In order to further enrich the theory of comprehensive exploration and coordinated development of multi-mineral resources, this paper takes the Huanghebei Coalfield as an example to systematically study the genesis mechanism and occurrence law of coal seam, coalbed methane, and coal-measure shale gas in Late Paleozoic and rich iron ore in Ordovician limestone underlie coal measure. The research is that: 1) The Late Paleozoic Carboniferous-Permian Marine facies, terrestrial facies, and transitional facies all developed in the coal-bearing area in the Huanghebei Coalfield, and the coal seams and mud shales developed well in Shanxi Formation and Taiyuan Formation. 2) Yanshanian magmatic intruded into Ordovician limestone. Contact metasomatism occurred between the ore-bearing hydrothermal fluids and the surrounding rocks, which led to skarn formation. The magnetite mineralization occurred in the metasomatism alteration process, and finally, the contact metasomatic iron deposit was formed; 3) Yanshanian magma intrusion has a significant impact on the generation of coal from coalbed methane and shale gas in the coal measures of Late Paleozoic. The magma carries a lot of heat by baking the coal seam and overlying shale, which is reflected explicitly in the increasing metamorphism degree of coal. Under the action of high temperature, the secondary gas of coal seam and coalbed methane increase sharply. The maturity and thermal evolution of organic matter in shale beds increased, and the shale gas entered a favorable range. The intrusion of magma greatly enhances the thermal evolution of organic matter in coal and shale, forming a variety of coals and promoting the generation and accumulation of coalbed methane and shale gas. At the same time, Mesozoic magmatic intrusion also controlled the formation of rich iron ores. According to the characteristics of mineral development and distribution in the study area, a multi-mineral development and distribution model of “coal - coalbed methane - shale gas - rich iron ore” coexists in the Huanghebei Coalfield, which is referred to as the “Huanghebei model”
Evaluation of the Energy Transition in the Process of Renewable Sources Expansion: A Case Study
Get PDFConsidering the risks related to energy security and the challenges posed by climate change, this work presents a methodology to investigate energy alternatives to promote an adequate energy transition. Such methodology was applied to a case study, modelling the energy system of the Brazilian State of Minas Gerais to subsidize an energy transition with a view to expanding renewable energies and promoting energy efficiency at the state and municipal levels, as well as combating climate change. Projections, in the 2030-2050 horizon, were made using the tool Long-range Energy Alternatives Planning System (LEAP) to establish a model of energy transition policy for Minas Gerais State. The modelling considered key assumptions based on historical data of demographic and economic origin, which subsidized the elaboration of three scenarios, being a Reference Scenario (REF), a Moderate Energy Transition Scenario (ETM) that aims to contribute to the energy sector goals of the Brazilian Nationally-Determined Contributions – NDC, and an Advanced Energy Transition Scenario (ETA) that goes beyond of NDC's goals. The analysis has shown that current policies are not sufficient to promote the state transition to sustainable energy systems and that this process will depend on the energy policies initiated and implemented in the near future
Energy, Exergy and Exergo-Economic Analysis of an OTEC Power Plant Utilizing Kalina Cycle
Get PDFThis study aims to analyse an Ocean Thermal Energy Conversion (OTEC) system through the use of a Kalina Cycle (KC), having a water-ammonia mixture as a working fluid. KC represents a technology capable of exploiting the thermal gap of ocean water. This system was then compared with OTEC systems, which exploit ammonia, R134A and butane-pentane mixture as working fluid. The comparison was carried on through energy analysis, exergetic analysis, and exergo-economic analysis using the EES (Engineering Equation Solver) software. For each case study, cost rates and auxiliary equations were evaluated for all components and the mass flow rate and unit exergy cost for each stream. The results showed that the KC with water-ammonia as working fluid achieves the best exergo-economic performance among the examined cycles. The cost of electricity produced through KC using water - ammonia mixture was found to be 26,66 c€/kWh. The thermal efficiency and the exergetic efficiency were calculated and the withdrawal depth of ocean water was considered. The efficiencies resulted to be 3.68% for the thermal efficiency and 95.96% for the exergetic efficiency