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排序方式： 共有3107条查询结果，搜索用时 27 毫秒
101.
Kai Wang;Chuanwen Sun; 《Greenhouse Gases: Science and Technology》2024,14(3):456-469
For shallow buried mines, the cracks generated due to the mining activities will connect the surface ground and the working face through the gob, which may result in the gas exchange between the surface and underground. In this study, we proposed the gob gas flow model and verified its applicability based on the measured data on site in our previous research and discussed the effect of delay time of pressure variation between working face and surface ground on the airflow direction according to the simulation. The results suggest that the delay time of pressure variation is the main factor affecting the pressure difference between surface and working face and airflow direction. Due to the characteristics of the surface pressure changes, the effect of delay time on airflow in gob is small in a short time, but this effect gradually increases with time. According to the airflow law in a cycle of pressure variation, the airflow direction in the gob is predictable when the delay time reaches a certain value, which can be interpreted clearly on the surface pressure variation diagram. This research may provide references for the measures taken against mine disasters caused by different airflow directions. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd. 相似文献
102.
Michel Deitermann Yannik Haver Bastian Timo Mei Martin Muhler 《Advanced Sustainable Systems》2024,8(2):2300329
Continuous methanol photooxidation in the gas phase is a promising method to produce valuable chemicals like formaldehyde or methyl formate in addition to hydrogen under mild conditions. The influence of the reaction conditions on the selectivity of methanol oxidation to formaldehyde is studied using a heated flat-plate flow photoreactor illuminated by an LED array (λmax = 368 nm) and Pt-modified SrTiO3. A combination of online analytical methods allowed to quantify all gaseous products during extended time-on-stream (> 48 h TOS). The selectivity to formaldehyde is found to be primarily determined by the residence time and the process temperature. At a low methanol to water ratio, methanol conversion and evolution of CO2 are favored, whereas the light intensity primarily influenced the apparent quantum yield from 5.1 to 1.8% at 9.36 to 52.93 mW cm−2, respectively, and the methanol conversion thus determining the economic efficiency of the process. Operation temperatures higher than 110 °C resulted in a strong deactivation of the catalyst while simultaneously the formation of CO at the expense of formaldehyde selectivity is favored. This study demonstrates the importance of understanding the influence of relevant reaction conditions and the potential of selective photocatalytic gas-phase oxidation of small molecules. 相似文献
103.
为了探究养猪废水中抗生素和重金属对潜流人工湿地土壤微生物和植物生长的影响,构建了水平潜流人工湿地和垂直潜流人工湿地,用“根袋”法区分芦苇根际和非根际土壤。每种潜流人工湿地根据进水差异设置4个处理组：进水为模拟养猪废水(CK组)、模拟养猪废水中添加抗生素(抗生素组)、模拟养猪废水中添加铜(Cu组)、模拟养猪废水中同时添加抗生素和Cu(抗生素+Cu组),对2种潜流人工湿地土壤呼吸和芦苇光合作用指标进行为期1年的监测。结果表明：养猪废水中添加18.3~39.1 µg·L−1抗生素或0.8~1.2 mg·L−1铜均可抑制潜流人工湿地的芦苇根际、非根际土壤呼吸和芦苇的光合作用。与CK组相比,在抗生素和Cu复合胁迫下,水平和垂直潜流人工湿地芦苇根际土壤呼吸分别下降了20.4%~66.3%和20.8%~77.5%,非根际土壤呼吸分别下降了30.4%~71.0%、23.2%~60.7%,垂直潜流人工湿地的芦苇根际、非根际土壤呼吸在春、夏、秋季均显著高于水平潜流人工湿地。在抗生素和Cu复合胁迫下,水平潜流人工湿地和垂直潜流人工湿地芦苇的株高在运行后期与CK组相比均显著降低。与CK组相比,水平潜流人工湿地和垂直潜流人工湿地芦苇净光合速率分别下降了11.0%~73.8%和15.2%~45.3%,气孔导度和蒸腾速率也受到了抑制,胞间CO2浓度则呈增加趋势。垂直潜流人工湿地比水平潜流人工湿地对养猪废水具有更好的深度处理能力。 相似文献
104.
《Advanced Sustainable Systems》2017,1(9)
A systematic approach is presented for increasing the concentration of redox‐active species in electrolytes for nonaqueous redox flow batteries (RFBs). Starting with an ionic liquid consisting of a metal coordination cation (MetIL), ferrocene‐containing ligands and iodide anions are substituted incrementally into the structure. While chemical structures can be drawn for molecules with 10 m redox‐active electrons (RAE), practical limitations such as melting point and phase stability constrain the structures to 4.2 m RAE, a 2.3× improvement over the original MetIL. Dubbed “MetILs3,” these ionic liquids possess redox activity in the cation core, ligands, and anions. Throughout all compositions, infrared spectroscopy shows the ethanolamine‐based ligands primarily coordinate to the Fe2+ core via hydroxyl groups. Calorimetry conveys a profound change in thermophysical properties, not only in melting temperature but also in suppression of a cold crystallization only observed in the original MetIL. Square wave voltammetry reveals redox processes characteristic of each molecular location. Testing a laboratory‐scale RFB demonstrates Coulombic efficiencies >95% and increased voltage efficiencies due to more facile redox kinetics, effectively increasing capacity 4×. Application of this strategy to other chemistries, optimizing melting point and conductivity, can yield >10 m RAE, making nonaqueous RFB a viable technology for grid scale storage. 相似文献
105.
106.
A detailed nitrogen (N) budget has been developed for an urban ecosystem based on the method of material flow analysis. How increased human activity and urbanisation influences N cycling have also been analysed. Total N input and output in the urban ecosystem of Zhengzhou City (ZUE) was calculated at 304.8?Gg was 275.3?Gg year?1, resulting in an N accumulation of 29.5?Gg year?1. Industry and human life activities, which respectively accounted for 43.8% and 34.2% of total N inputs and 52.6% and 29.1% of total N outputs, were the core of N flow in the urban ecosystem. Humans activities mediated more than 98% N inputs into the ZUE, 73.2% of N was released into the atmosphere and 11.7% into hydrosphere. This very large volume of released N could contribute to regional problems. High energy consumption, insufficient wastewater treatment facility practices, and low N use efficiency are the primary causes of pollution. The major challenge ahead for the urban ecosystem is how to manage high-intensity N pollutant inputs to the urban ecosystems coupled with incomplete N cycling and removal. Based on the analysis of the N budget and loading, this study also proposes an N management strategy for the ZUE. 相似文献
107.
《Advanced Sustainable Systems》2018,2(3)
Nonaqueous redox flow batteries based on redox‐active organic materials (ROMs) are attractive for stationary energy storage applications, but inferior energy densities are demonstrated in reported systems. To address this limitation, a nonaqueous organic flow battery using two‐electron anthraquinone anolyte and phenothiazine catholyte materials is developed. Structural tailoring leads to greatly improved solubilities with the cell potentials of 1.63 and 2.80 V for the first and second electron transfer reactions, respectively, of optimized ROMs. Doubled charge storage capacities indicative of 2e− reactions are achieved in proof‐of‐concept bulk electrolyte and flow cell demonstrations, albeit with only modest cyclability due to the limited stability of the second redox event. Although further improvement is still needed to attract practical interest, this study opens a promising pathway to increase the energy density for organic flow batteries and is expected to inspire more in‐depth studies of energy dense, stable ROMs. 相似文献
108.
Samin Raziperchikolaee Ola Babarinde Joel Sminchak Neeraj Gupta 《Greenhouse Gases: Science and Technology》2019,9(6):1247-1265
Understanding the distribution and orientation of natural fractures within Knox Groups is of significance in seeking potential CO2 storage zones with high practical storage capacity. Over 700 observations of natural fractures were interpreted on acquired resistivity and acoustic image logs collected at multiple well locations ranging in depth from 730 to 3900 m in the Knox Group interval on the western flank of Appalachian Basin. We evaluated the structural parameters of the fractures using statistical analysis. Natural fracture intensity was observed to increase up‐dip within the studied area. The present day maximum horizontal stress direction was derived using the interpretation of wellbore breakouts and drilling‐induced tensile fractures in image logs. Overall, a high percentage of fractures with varying dip directions were observed to strike subparallel to the contemporary maximum horizontal stress direction. Multiphase flow–geomechanics coupled numerical simulations and poromechanics analytical solutions were then used to study pressure and stress response of CO2 injection into the fractured Knox reservoirs. In addition, we applied a dual permeability model combined with a fracture activation model to study the permeability enhancement and its effect on injection mass increase. We also showed the line source injection solution can reasonably predict stress changes of CO2 injection into the deep saline formations. Results were analyzed to understand the potential effect of natural fractures in sandstone formations and fractured layers in thick carbonate formations on CO2‐injected mass, time‐dependent stress evolution, and the ratio of stress to pore pressure changes. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd. 相似文献
109.
Weiqiang Song Junming Zhang Chunguang Wang Shaojie Chen Zhongwei Chen 《Greenhouse Gases: Science and Technology》2019,9(5):999-1009
To investigate the flow field near fracture entrance and promote the development of sand fracturing with carbon dioxide as the working fluid, numerical simulation of multiphase flow was conducted with a 3D geological model considering the compressibility of carbon dioxide. The flow field of carbon dioxide alone was firstly investigated to lay the foundation for the analysis of multiphase flow, and then comparative analysis was conducted on the flow field of both the injecting sand from the pipe and the annulus. The results show that jet fracture with carbon dioxide can achieve a 4.46 MPa pressure boost at the fracture tip compared to the annulus pressure, which theoretically validates the feasibility of the mentioned technology. Sand fracturing can achieve a higher pressure boost in the cavity, while it needs greater pump pressure at the surface. Injecting sand from the annulus could decrease the need for pump pressure by 6.62 MPa at the condition of injecting 25% carbon dioxide from the annulus simultaneously, while the pressure difference between the cavity tip and the annulus decreases as a result. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd. 相似文献
110.
利用AA3流动注射分析仪,同时对地表水中的挥发酚和氰化物进行测定,分析流程中使用了在线恒温蒸馏器。同传统的分析方法相比,本法分析测定数据准确、可靠、高效,大大缩短了测定时间,只需将两种标准配制成混合标样,一次取样完成两个项目的测定。回收率为90％～110％,相关系数达到0．9992以上。 相似文献