Eng Pub Date : 2023-12-11 DOI: 10.3390/eng4040168

Yuki Nakagawa, Kano Yoshida, Daisaku Kaneko, Shin-ichi Ikeda

引用次数: 0

Visualization of Movement and Expansion of Coal Reaction Zone by Acoustic Emission Monitoring in Underground Coal Gasification System 通过声发射监测可视化地下煤气化系统中煤炭反应区的移动和扩展

Eng Pub Date : 2023-11-30 DOI: 10.3390/eng4040166

Rika Iriguchi, Yuma Ishii, A. Hamanaka, Faqiang Su, Ken-ichi Itakura, Jun-ichi Kodama, T. Sasaoka, H. Shimada, G. Deguchi

{"title":"Visualization of Movement and Expansion of Coal Reaction Zone by Acoustic Emission Monitoring in Underground Coal Gasification System","authors":"Rika Iriguchi, Yuma Ishii, A. Hamanaka, Faqiang Su, Ken-ichi Itakura, Jun-ichi Kodama, T. Sasaoka, H. Shimada, G. Deguchi","doi":"10.3390/eng4040166","DOIUrl":"https://doi.org/10.3390/eng4040166","url":null,"abstract":"Underground coal gasification (UCG) is the process of directly recovering energy as combustible gases such as hydrogen and carbon monoxide by combusting unmined coal resources in situ. The UCG process is an invisible phenomenon, in which fracturing activity at high temperature (>1000 °C) in coal seams expands the gasification zone and increases the combustible components of the product gas. However, excessive expansion of the gasification zone may cause environmental problems such as gas leakage, deformation of the surrounding ground, and groundwater pollution. Therefore, visualization of the gasification zone of UCG is required for both improving gasification efficiency and developing UCG systems with low environmental impact. In this study, the large-scale model UCG experiments conducted on a laboratory scale (size: 625 mm × 650 mm × 2792 mm (H × W × L)) were carried out to discuss the visualization of the gasification reaction zone of coal in UCG by Acoustic Emission (AE) technique with uniaxial and triaxial acceleration transducers. As the results of temperature monitoring and AE source location analysis show, AE sources are located near the high-temperature zone (>1000 °C). In addition, the located AE sources move and expand with the movement and expansion of the high-temperature zone. AE measurement can be a useful technique for monitoring the progress of the UCG reaction zone. AE measurement with triaxial sensors is also useful to predict a high-temperature zone though the measurable range, which has to be considered.","PeriodicalId":502660,"journal":{"name":"Eng","volume":"118 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139199195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Activity Concentration Index Values for Concrete Multistory Residences in Greece Due to Fly Ash Addition in Cement 由于在水泥中添加粉煤灰，希腊混凝土多层住宅的活性浓度指数值

Eng Pub Date : 2023-11-20 DOI: 10.3390/eng4040164

Stamatia Gavela, Georgios Papadakos

{"title":"Activity Concentration Index Values for Concrete Multistory Residences in Greece Due to Fly Ash Addition in Cement","authors":"Stamatia Gavela, Georgios Papadakos","doi":"10.3390/eng4040164","DOIUrl":"https://doi.org/10.3390/eng4040164","url":null,"abstract":"According to 2013/59/Euratom Directive, the activity concentration index (ACI) is required to be estimated for each building material that is of concern from a radiation protection point of view. This index applies to building materials and not to constituents that cannot be used as building materials themselves. Fly ash is a byproduct of coal-fired power plants and is one of the main constituents of cement. The radioactivity in fly ash that is produced by Greek lignite power plants cannot be considered insignificant. For example, in the case of the Megalopolis power plant, the concentration for radioisotopes of the 226Ra chain is found to be about 1 kBq/kg. Since natural radionuclide concentrations, which are harmful to human health in terms of radiation exposure, exist in fly ash, ACI should be assessed for building materials containing fly ash. The present study evaluates the ACI of concrete containing fly ash cement when used in multistory residential buildings. Results showed that cement produced in Greece by the three main Greek cement production plants, containing lignite fly ash, and used as a material for concrete multistory constructions, should not be considered as “of concern from a radiation protection point of view”. Each country that wishes to evaluate the use of fly ash into constructions should repeat the method for the ACI uncertainty budget proposed in this study, to assess whether it significantly exceeds the reference value (whether it is of concern from a radiation protection point of view).","PeriodicalId":502660,"journal":{"name":"Eng","volume":"51 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139255101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Snap-Off during Imbibition in Porous Media: Mechanisms, Influencing Factors, and Impacts 多孔介质浸润过程中的断裂：机理、影响因素和影响

Eng Pub Date : 2023-11-17 DOI: 10.3390/eng4040163

Guiheng Li, Jia Yao

{"title":"Snap-Off during Imbibition in Porous Media: Mechanisms, Influencing Factors, and Impacts","authors":"Guiheng Li, Jia Yao","doi":"10.3390/eng4040163","DOIUrl":"https://doi.org/10.3390/eng4040163","url":null,"abstract":"The phenomenon of snap-off during imbibition in porous media, a fundamental two-phase fluid flow phenomenon, plays a crucial role in both crude oil production and carbon dioxide (CO2) utilization and storage. In porous media where two phases coexist, the instability of the phase interface may give rise to various displacement phenomena, including pore–body filling, piston-like displacement, and snap-off. Snap-off, characterized by the generation of discrete liquid droplets or gas bubbles, assumes paramount significance. This study provides a comprehensive overview of snap-off mechanisms, influencing factors, and impacts. Snap-off initiation arises from variations in the curvature radius at the interface between two phases within narrow regions, primarily influenced by capillary pressure. It can be influenced by factors such as the characteristics of multiphase fluids, the wettability of porous media, as well as the pore–throat geometry and topology within porous media. In turn, snap-off exerts a discernible influence on the fluid dynamics within the porous medium, resulting in impacts that encompass unrecoverable oil droplet formation, the oil bridging effect, drainage–imbibition hysteresis, strong foam generation and transient/dynamic effects. Although the snap-off phenomenon exerts detrimental effects during the conventional waterflooding in oil production, its potential is harnessed for beneficial outcomes in CO2-EOR and CO2 storage. This study significantly advances our understanding of snap-off and its multifaceted roles in multiphase fluid dynamics, offering vital insights for the precise prediction of fluid flow behavior and strategic control. These valuable insights can serve as a theoretical foundation to guide our deliberate modulation of snap-off phenomena, aiming at optimizing oil-recovery processes and enhancing the safety and stability of CO2 storage.","PeriodicalId":502660,"journal":{"name":"Eng","volume":"38 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139265454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Perceptions of Construction Risks Due to Fast-Track Activity Overlapping 对 "快车道 "活动造成的施工风险的看法重叠

Eng Pub Date : 2023-11-17 DOI: 10.3390/eng4040162

Claudia Garrido Martins, S. Bogus, Vanessa Valentin

引用次数: 0

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