Accurate measurement of the pore size distribution (PSD) in coals is crucial for guiding subsequent coalbed methane (CBM) engineering practice. Currently, mercury intrusion porosimetry (MIP) measurement has been widely used as a PSD testing method due to its effectiveness and convenience. Nevertheless, it is worth noting that the elevated pressure during the MIP experiments can lead to matrix compressibility, potentially causing inaccurate estimations of PSD in coals. Therefore, correction methods are used to modify the PSD in the high-pressure segment to improve the accuracy of MIP data. This study proposed a novel method with higher accuracy and convenience for calculating the matrix compressibility coefficient compared to the traditional calculation methods. Firstly, the matrix compressibility coefficients of six coal samples were calculated by using low-temperature nitrogen adsorption (LTNA) data. Subsequently, by utilizing the mathematical correlation between Kc (the compressibility coefficient of the coal matrix) and Ro,max (the maximum vitrinite reflectance) from prior research, a novel statistical method was designed to determine the matrix compressibility coefficient of the samples. Finally, the statistical matrix compressibility coefficient determination method was used to examine the fractal characteristics of the actual PSD. The results indicate that when the pressure exceeds 24 MPa, the volume obtained from mercury intrusion exceeds the pore volume measurement. The Kc calculated using the traditional correction method is in the range of 0.876–1.184 × 10−10 m2/N, while the Kc values of our proposed statistical correction method range from 0.898 × 10−10 to 1.233 × 10−10 m2/N, with a comparison error rate of ~0.11–5.25%. The MIP data greater than 24 MPa were effectively corrected using the statistical correction method, thus reducing the mercury intrusion volume error by 91.75–96.40%. Additionally, the corrected pore fractal dimension (D2) values fall within the range of 2.792 to 2.975, which are closer to the actual values than the pore fractal dimension range of 3.186 to 3.339.
{"title":"Re-Calibrating the Mercury-Intrusion-Porosimetry-Measured Pore Size Distribution of Coals: A Novel Method for Calculating the Matrix Compression Coefficient","authors":"Bin Ren, Sijian Zheng, Lihua Ping, Meng Wang, Xuguang Dai, Yanzhi Liu, Shen Xu, Xiuping Wu","doi":"10.3390/pr12091928","DOIUrl":"https://doi.org/10.3390/pr12091928","url":null,"abstract":"Accurate measurement of the pore size distribution (PSD) in coals is crucial for guiding subsequent coalbed methane (CBM) engineering practice. Currently, mercury intrusion porosimetry (MIP) measurement has been widely used as a PSD testing method due to its effectiveness and convenience. Nevertheless, it is worth noting that the elevated pressure during the MIP experiments can lead to matrix compressibility, potentially causing inaccurate estimations of PSD in coals. Therefore, correction methods are used to modify the PSD in the high-pressure segment to improve the accuracy of MIP data. This study proposed a novel method with higher accuracy and convenience for calculating the matrix compressibility coefficient compared to the traditional calculation methods. Firstly, the matrix compressibility coefficients of six coal samples were calculated by using low-temperature nitrogen adsorption (LTNA) data. Subsequently, by utilizing the mathematical correlation between Kc (the compressibility coefficient of the coal matrix) and Ro,max (the maximum vitrinite reflectance) from prior research, a novel statistical method was designed to determine the matrix compressibility coefficient of the samples. Finally, the statistical matrix compressibility coefficient determination method was used to examine the fractal characteristics of the actual PSD. The results indicate that when the pressure exceeds 24 MPa, the volume obtained from mercury intrusion exceeds the pore volume measurement. The Kc calculated using the traditional correction method is in the range of 0.876–1.184 × 10−10 m2/N, while the Kc values of our proposed statistical correction method range from 0.898 × 10−10 to 1.233 × 10−10 m2/N, with a comparison error rate of ~0.11–5.25%. The MIP data greater than 24 MPa were effectively corrected using the statistical correction method, thus reducing the mercury intrusion volume error by 91.75–96.40%. Additionally, the corrected pore fractal dimension (D2) values fall within the range of 2.792 to 2.975, which are closer to the actual values than the pore fractal dimension range of 3.186 to 3.339.","PeriodicalId":20597,"journal":{"name":"Processes","volume":"62 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiangtao Chen, Jinxing Wang, Huawei Jiang, Xiangli Zuo, Xin Yang
To know the sustainable performance of calcium-based adsorbents is one of the important aspects to realize efficient and economical carbon capture, and to systematically study the properties of natural adsorbents is conducive to their industrialization. The cyclic calcination and carbonation characteristics of a typical natural limestone were investigated using a thermal gravimetric analyzer. Two kinds of over-sintering conditions were selected to emphatically study the cyclic separation of CO2 from limestones through prolonging the calcination time and increasing the calcination temperature. The results showed that the untimely end of the chemical reaction control stage caused by excessive sintering is the direct reason for the reduction in cyclic carbonation conversion, and the changes in surface morphology of calcined products due to pore collapse and fusion are the fundamental reasons for the reduction in cyclic carbonation conversion. The excessive sintering caused by extending the calcining time or increasing the calcining temperature has great inhibition on this cycle only; the inhibition decreases rapidly in subsequent cycles. In addition, SEM and BET–BJH tests further confirm the influence of the over-sintering phenomenon. With the further increase in cycle number, the early excessive sintering has certain stimulative effects on the subsequent carbonation reaction. It is expected to provide a reference for the subsequent research and development of natural calcium-based adsorbents.
{"title":"Effects of Over-Sintering on Cyclic Calcination and Carbonization of Natural Limestone for CO2 Capture","authors":"Jiangtao Chen, Jinxing Wang, Huawei Jiang, Xiangli Zuo, Xin Yang","doi":"10.3390/pr12091926","DOIUrl":"https://doi.org/10.3390/pr12091926","url":null,"abstract":"To know the sustainable performance of calcium-based adsorbents is one of the important aspects to realize efficient and economical carbon capture, and to systematically study the properties of natural adsorbents is conducive to their industrialization. The cyclic calcination and carbonation characteristics of a typical natural limestone were investigated using a thermal gravimetric analyzer. Two kinds of over-sintering conditions were selected to emphatically study the cyclic separation of CO2 from limestones through prolonging the calcination time and increasing the calcination temperature. The results showed that the untimely end of the chemical reaction control stage caused by excessive sintering is the direct reason for the reduction in cyclic carbonation conversion, and the changes in surface morphology of calcined products due to pore collapse and fusion are the fundamental reasons for the reduction in cyclic carbonation conversion. The excessive sintering caused by extending the calcining time or increasing the calcining temperature has great inhibition on this cycle only; the inhibition decreases rapidly in subsequent cycles. In addition, SEM and BET–BJH tests further confirm the influence of the over-sintering phenomenon. With the further increase in cycle number, the early excessive sintering has certain stimulative effects on the subsequent carbonation reaction. It is expected to provide a reference for the subsequent research and development of natural calcium-based adsorbents.","PeriodicalId":20597,"journal":{"name":"Processes","volume":"5 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142188074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alkali-activated slag cementitious (AASC) foamed concrete (FC) has presented challenges such as rapid setting time and poor working performance. The use of sodium citrate (Na3Cit) as a retarding agent can improve the workability and microstructure of AASC foamed concrete. The effects of the dosage, modulus of water glass (WG, the main component is Na2O·nSiO2), and retarding agent on the properties and structure of FC were studied in this paper. The results indicated that using a water binder ratio of 0.4, WG with a modulus of 1.2, and an additional amount of 15% and 0.5% of Na3Cit, the prepared FC had a flowability of 190 mm. Its initial and final setting times were 3.7 h and 35.3 h. Its 7 d and 28 d compressive strengths reached 1.1 MPa and 1.5 MPa, respectively. After hardening, the pore walls were dense and consistent in size, with few larger pores and nearly spherical shapes. The addition of Na3Cit resulted in the formation of calcium citrate, which adsorbed onto the slag surface. This hindered the initial dissolution of the slag, reduced the number of hydration products produced, and decreased the early strength. With increasing curing time, the slag in the FC mixture dissolved further. This led to the decomposition of a portion of calcium citrate and the release of Ca2+. The Ca2+ reacted with [Si(OH)4]4− and [Al(OH)4]−, creating more C-(A)-S-H gel. This gel filled the voids in the FC and repaired any defects on the pore walls. Ultimately, this process increased the compressive strength of the FC in the later stages.
{"title":"The Effects of Sodium Silicate and Sodium Citrated on the Properties and Structure of Alkali-Activated Foamed Concrete","authors":"Hao Liu, Gaoke Zhang, Jixin Li, Jiaqi Xuan, Yongsheng Wang, Huiwen Wan, Yun Huang","doi":"10.3390/pr12091927","DOIUrl":"https://doi.org/10.3390/pr12091927","url":null,"abstract":"Alkali-activated slag cementitious (AASC) foamed concrete (FC) has presented challenges such as rapid setting time and poor working performance. The use of sodium citrate (Na3Cit) as a retarding agent can improve the workability and microstructure of AASC foamed concrete. The effects of the dosage, modulus of water glass (WG, the main component is Na2O·nSiO2), and retarding agent on the properties and structure of FC were studied in this paper. The results indicated that using a water binder ratio of 0.4, WG with a modulus of 1.2, and an additional amount of 15% and 0.5% of Na3Cit, the prepared FC had a flowability of 190 mm. Its initial and final setting times were 3.7 h and 35.3 h. Its 7 d and 28 d compressive strengths reached 1.1 MPa and 1.5 MPa, respectively. After hardening, the pore walls were dense and consistent in size, with few larger pores and nearly spherical shapes. The addition of Na3Cit resulted in the formation of calcium citrate, which adsorbed onto the slag surface. This hindered the initial dissolution of the slag, reduced the number of hydration products produced, and decreased the early strength. With increasing curing time, the slag in the FC mixture dissolved further. This led to the decomposition of a portion of calcium citrate and the release of Ca2+. The Ca2+ reacted with [Si(OH)4]4− and [Al(OH)4]−, creating more C-(A)-S-H gel. This gel filled the voids in the FC and repaired any defects on the pore walls. Ultimately, this process increased the compressive strength of the FC in the later stages.","PeriodicalId":20597,"journal":{"name":"Processes","volume":"29 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142188071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Biochar, an eco-friendly, porous carbon-rich material, is widely studied for immobilizing heavy metals in contaminated environments. This study prepared tobacco stalks, a typical agricultural waste, into biochar (TSB) modified by hydroxyapatite (HAP) at co-pyrolysis temperatures of 350 °C and 550 °C to explore its Cd(II) adsorption behavior and relevant mechanisms. XRD, SEM–EDS, FTIR, and BET analyses revealed that HAP successfully incorporated onto TSB, enriching the surface oxygen-containing functional groups (P–O and carboxyl), and contributing to the enhancement of the specific surface area from 2.52 (TSB350) and 3.63 m2/g (TSB550) to 14.07 (HAP–TSB350) and 18.36 m2/g (HAP–TSB550). The kinetics of Cd(II) adsorption onto TSB and HAP–TSB is well described by the pseudo-second-order model. Isotherm results revealed that the maximum adsorption capacities of Cd(II) on HAP–TSB350 and HAP–TSB550 were approximately 13.17 and 14.50 mg/g, 2.67 and 9.24 times those of TSB350 and TSB550, respectively. The Cd(II) adsorption amounts on TSBs and HAP–TSBs increased significantly with increasing pH, especially in HAP–TSB550. Ionic strength effects and XPS analysis showed that Cd(II) adsorption onto HAP–TSBs occurred mainly via electrostatic interaction, cation exchange with Ca2+, complexation with P–O and –COOH, and surface precipitation. These findings will provide a modification strategy for the reutilization of tobacco agricultural waste in the remediation of heavy metal contaminated areas.
{"title":"Nano-Hydroxyapatite Modified Tobacco Stalk-Based Biochar for Immobilizing Cd(II): Interfacial Adsorption Behavior and Mechanisms","authors":"Tianfu Li, Xiaofei Li, Chaoran Shen, Dian Chen, Fuhua Li, Weicheng Xu, Xiaolian Wu, Yanping Bao","doi":"10.3390/pr12091924","DOIUrl":"https://doi.org/10.3390/pr12091924","url":null,"abstract":"Biochar, an eco-friendly, porous carbon-rich material, is widely studied for immobilizing heavy metals in contaminated environments. This study prepared tobacco stalks, a typical agricultural waste, into biochar (TSB) modified by hydroxyapatite (HAP) at co-pyrolysis temperatures of 350 °C and 550 °C to explore its Cd(II) adsorption behavior and relevant mechanisms. XRD, SEM–EDS, FTIR, and BET analyses revealed that HAP successfully incorporated onto TSB, enriching the surface oxygen-containing functional groups (P–O and carboxyl), and contributing to the enhancement of the specific surface area from 2.52 (TSB350) and 3.63 m2/g (TSB550) to 14.07 (HAP–TSB350) and 18.36 m2/g (HAP–TSB550). The kinetics of Cd(II) adsorption onto TSB and HAP–TSB is well described by the pseudo-second-order model. Isotherm results revealed that the maximum adsorption capacities of Cd(II) on HAP–TSB350 and HAP–TSB550 were approximately 13.17 and 14.50 mg/g, 2.67 and 9.24 times those of TSB350 and TSB550, respectively. The Cd(II) adsorption amounts on TSBs and HAP–TSBs increased significantly with increasing pH, especially in HAP–TSB550. Ionic strength effects and XPS analysis showed that Cd(II) adsorption onto HAP–TSBs occurred mainly via electrostatic interaction, cation exchange with Ca2+, complexation with P–O and –COOH, and surface precipitation. These findings will provide a modification strategy for the reutilization of tobacco agricultural waste in the remediation of heavy metal contaminated areas.","PeriodicalId":20597,"journal":{"name":"Processes","volume":"7 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The No. 3 coal seam in the Yuxi Coal Mine has a measured maximum gas content of 25.59 m3/t, along with a maximum gas pressure of 2.9 MPa, indicating its high risk to gas and outbursts. To mitigate outburst risks of the coal seam, the 1301 working face has been implemented with gas pre-drainage measures by grid boreholes from underlying roadways. After one year of extraction, it was confirmed that the gas content at all 33 test sites was below 8 m3/t, meeting the outburst prevention standards. However, during subsequent coal tunnel excavation, the gas desorption index K1 value frequently exceeded the standard, resulting in numerous occurrences of abnormal gas emission or small-scale outbursts. To tackle the challenges associated with safe excavation following the first-round regional outburst prevention measures, a research and industrial trial of CO2 gas fracturing (CO2-Frac) technology for secondary outburst prevention and rapid excavation was completed. The results show that the dual-hole and high-pressure (185 MPa) CO2-Frac considerably contributes to outburst prevention. K1 exceedances per hundred meters of tunnel excavations were from an average of 2.54 without CO2-Frac to an average of 0.28 after the new technology was implemented, leading to an eight-fold reduction. Additionally, the monthly excavation footage increased from an average of 81.64 m without CO2-Frac to an average of 162.42 m with CO2-Frac, resulting in a two-fold improvement. The dual-hole and high-pressure CO2-Frac is an advanced technology for safe and efficient excavation for secondary outburst elimination in highly outburst-prone coal seams in the Yuxi Coal Mine, with potential for widespread application in similar coal seam conditions.
{"title":"Study on Safety Tunneling Technology of Secondary Outburst Elimination by CO2 Gas Fracturing in High-Outburst Coal Seam","authors":"Zongwei Xu, Junsheng Zhang, Yunxing Cao, Zhenzhi Wang, Xinsheng Zhang","doi":"10.3390/pr12091925","DOIUrl":"https://doi.org/10.3390/pr12091925","url":null,"abstract":"The No. 3 coal seam in the Yuxi Coal Mine has a measured maximum gas content of 25.59 m3/t, along with a maximum gas pressure of 2.9 MPa, indicating its high risk to gas and outbursts. To mitigate outburst risks of the coal seam, the 1301 working face has been implemented with gas pre-drainage measures by grid boreholes from underlying roadways. After one year of extraction, it was confirmed that the gas content at all 33 test sites was below 8 m3/t, meeting the outburst prevention standards. However, during subsequent coal tunnel excavation, the gas desorption index K1 value frequently exceeded the standard, resulting in numerous occurrences of abnormal gas emission or small-scale outbursts. To tackle the challenges associated with safe excavation following the first-round regional outburst prevention measures, a research and industrial trial of CO2 gas fracturing (CO2-Frac) technology for secondary outburst prevention and rapid excavation was completed. The results show that the dual-hole and high-pressure (185 MPa) CO2-Frac considerably contributes to outburst prevention. K1 exceedances per hundred meters of tunnel excavations were from an average of 2.54 without CO2-Frac to an average of 0.28 after the new technology was implemented, leading to an eight-fold reduction. Additionally, the monthly excavation footage increased from an average of 81.64 m without CO2-Frac to an average of 162.42 m with CO2-Frac, resulting in a two-fold improvement. The dual-hole and high-pressure CO2-Frac is an advanced technology for safe and efficient excavation for secondary outburst elimination in highly outburst-prone coal seams in the Yuxi Coal Mine, with potential for widespread application in similar coal seam conditions.","PeriodicalId":20597,"journal":{"name":"Processes","volume":"8 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142188072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaoyue Huang, Ya Mo, Wanchao Wu, Miaojia Ye, Chuanqun Hu
With the rapid advancement of the flexible electronics industry, there is an urgent need to enhance the mechanical properties and thermal stability of flexible electronic devices to expand their range of applications. To address this need, flexible conductive composites have been developed using waterborne polyurethane (WPU) as the matrix, carbon nanotubes (CNTs) and graphene (GA) as conductive fillers, and incorporating cellulose nanofibers (CNFs). The carbon fillers create a conductive and thermal conductivity network within the matrix, while the presence of CNFs improves the dispersion of CNTs and GA, thereby enhancing the overall network structure. The resulting WGNF composites exhibit a resistivity of up to 1.05 × 104 Ω·cm, a tensile strength of 26.74 MPa, and a thermal conductivity of 0.494 W/(m·K). This demonstrates that incorporating cellulose offers an effective solution for producing high-performance polymeric conductive and thermally conductive composites, showing promising potential for flexible wearable devices.
{"title":"Preparation and Properties of Waterborne Polyurethane/Carbon Nanotube/Graphene/Cellulose Nanofiber Composites","authors":"Xiaoyue Huang, Ya Mo, Wanchao Wu, Miaojia Ye, Chuanqun Hu","doi":"10.3390/pr12091913","DOIUrl":"https://doi.org/10.3390/pr12091913","url":null,"abstract":"With the rapid advancement of the flexible electronics industry, there is an urgent need to enhance the mechanical properties and thermal stability of flexible electronic devices to expand their range of applications. To address this need, flexible conductive composites have been developed using waterborne polyurethane (WPU) as the matrix, carbon nanotubes (CNTs) and graphene (GA) as conductive fillers, and incorporating cellulose nanofibers (CNFs). The carbon fillers create a conductive and thermal conductivity network within the matrix, while the presence of CNFs improves the dispersion of CNTs and GA, thereby enhancing the overall network structure. The resulting WGNF composites exhibit a resistivity of up to 1.05 × 104 Ω·cm, a tensile strength of 26.74 MPa, and a thermal conductivity of 0.494 W/(m·K). This demonstrates that incorporating cellulose offers an effective solution for producing high-performance polymeric conductive and thermally conductive composites, showing promising potential for flexible wearable devices.","PeriodicalId":20597,"journal":{"name":"Processes","volume":"13 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jasmina Dostanić, Davor Lončarević, Milica Hadnađev-Kostić, Tatjana Vulić
In recent decades, the rising wastewater output from industrial pollution has inflicted severe harm on both surface and groundwater, leading to substantial environmental damage. The elimination of harmful, toxic materials and wastewater remediation are pressing global concerns and pose a formidable challenge for scientists worldwide. Heterogeneous photocatalysis has been recognized as a promising, effective, energy-free, and eco-friendly process capable of completely degrading various organic pollutants. Finding a material that simultaneously satisfies various thermodynamic and kinetic criteria, coupled with good thermal- and photo-stability, is a challenging task necessitating the modification of existing materials or the synthesis of new ones to meet the required standards. This present study comprehensibly elaborates on different approaches to the modification of various photocatalytic systems, both organic and inorganic, in order to obtain more efficient and feasible catalysts for practical applications. In addition, the current status of the application of photocatalysts in dye wastewater treatment is summarized, projecting the future direction for wastewater management by photocatalytic processes.
{"title":"Recent Advances in the Strategies for Developing and Modifying Photocatalytic Materials for Wastewater Treatment","authors":"Jasmina Dostanić, Davor Lončarević, Milica Hadnađev-Kostić, Tatjana Vulić","doi":"10.3390/pr12091914","DOIUrl":"https://doi.org/10.3390/pr12091914","url":null,"abstract":"In recent decades, the rising wastewater output from industrial pollution has inflicted severe harm on both surface and groundwater, leading to substantial environmental damage. The elimination of harmful, toxic materials and wastewater remediation are pressing global concerns and pose a formidable challenge for scientists worldwide. Heterogeneous photocatalysis has been recognized as a promising, effective, energy-free, and eco-friendly process capable of completely degrading various organic pollutants. Finding a material that simultaneously satisfies various thermodynamic and kinetic criteria, coupled with good thermal- and photo-stability, is a challenging task necessitating the modification of existing materials or the synthesis of new ones to meet the required standards. This present study comprehensibly elaborates on different approaches to the modification of various photocatalytic systems, both organic and inorganic, in order to obtain more efficient and feasible catalysts for practical applications. In addition, the current status of the application of photocatalysts in dye wastewater treatment is summarized, projecting the future direction for wastewater management by photocatalytic processes.","PeriodicalId":20597,"journal":{"name":"Processes","volume":"1 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142188099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As a crucial reserve for natural gas, the safe operation of underground gas storage facilities is paramount for seasonal peak shaving and emergency supply security. Focusing on the Lei X gas storage facility in the Liaohe Basin of China, this study delves into the mechanical integrity of gas storage facilities and assesses the upper limit pressure for safe operation. Leveraging seismic logging data, we conducted an analysis and statistical evaluation of boundary faults and top cover characteristics, integrating regional stress fields and rock mechanics to evaluate fault activation pressure and cover failure risk using a fault activation pressure assessment method. This research elucidates the maximum safe operating pressure for underground gas storage facilities. The research findings suggest that the sealing layer of the Lei X gas storage reservoir exhibits a predominant hydro-fracturing pattern. Under the existing stress field conditions, the sealing layer demonstrates favorable sealing properties, and the boundary faults remain relatively stable. Moreover, through data extraction and quantitative analysis, this study clearly determined the critical pressure at which each fault is activated and the pressure at which the sealing layer undergoes hydro-fracturing during cyclic injection and the production of gas storage. Considering the activation pressure and fracturing pressure data for the sealing layer, a secure operating pressure of 15.0 MPa was calculated for gas storage operations. This study offers crucial theoretical support for enhancing injection and production efficiency, as well as ensuring the safe operation of Lei X gas storage and providing technical guidance for future adjustments to injection and production schemes.
{"title":"Investigation of the Upper Safety Operating Pressure Limit for Underground Gas Storage Using the Fault Activation Pressure Evaluation Method","authors":"Xianxue Chen, Tianguang Zhang, Haibo Wen, Yejun Jin, Lingdong Meng","doi":"10.3390/pr12091910","DOIUrl":"https://doi.org/10.3390/pr12091910","url":null,"abstract":"As a crucial reserve for natural gas, the safe operation of underground gas storage facilities is paramount for seasonal peak shaving and emergency supply security. Focusing on the Lei X gas storage facility in the Liaohe Basin of China, this study delves into the mechanical integrity of gas storage facilities and assesses the upper limit pressure for safe operation. Leveraging seismic logging data, we conducted an analysis and statistical evaluation of boundary faults and top cover characteristics, integrating regional stress fields and rock mechanics to evaluate fault activation pressure and cover failure risk using a fault activation pressure assessment method. This research elucidates the maximum safe operating pressure for underground gas storage facilities. The research findings suggest that the sealing layer of the Lei X gas storage reservoir exhibits a predominant hydro-fracturing pattern. Under the existing stress field conditions, the sealing layer demonstrates favorable sealing properties, and the boundary faults remain relatively stable. Moreover, through data extraction and quantitative analysis, this study clearly determined the critical pressure at which each fault is activated and the pressure at which the sealing layer undergoes hydro-fracturing during cyclic injection and the production of gas storage. Considering the activation pressure and fracturing pressure data for the sealing layer, a secure operating pressure of 15.0 MPa was calculated for gas storage operations. This study offers crucial theoretical support for enhancing injection and production efficiency, as well as ensuring the safe operation of Lei X gas storage and providing technical guidance for future adjustments to injection and production schemes.","PeriodicalId":20597,"journal":{"name":"Processes","volume":"8 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142188073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yumeng Zhao, Alexander Russell, Kingsly Ambrose, Carl R. Wassgren
High-efficiency particulate air (HEPA) filter purifiers are a recommended method for eliminating respiratory airborne droplets. In this study, the movement of airborne droplets exhaled by occupants in an unventilated, two-bed dormitory room with an air purifier was simulated using computational fluid dynamics. The air was modeled using an Eulerian scheme while the droplets were modeled using a Lagrangian method. The airborne droplet number, the rate at which droplets are removed, and the rate at which droplets accumulate were calculated. A larger HEPA flow rate increased the droplet removal efficiency, with most of the droplets settling on boundary surfaces. Of particular note, the air purifier location within the room had a significant impact on reducing the droplet exchange between two occupants and improving the droplet elimination efficiency.
{"title":"Prediction of Air Purifier Effectiveness for Eliminating Exhaled Droplets in a Confined Room","authors":"Yumeng Zhao, Alexander Russell, Kingsly Ambrose, Carl R. Wassgren","doi":"10.3390/pr12091917","DOIUrl":"https://doi.org/10.3390/pr12091917","url":null,"abstract":"High-efficiency particulate air (HEPA) filter purifiers are a recommended method for eliminating respiratory airborne droplets. In this study, the movement of airborne droplets exhaled by occupants in an unventilated, two-bed dormitory room with an air purifier was simulated using computational fluid dynamics. The air was modeled using an Eulerian scheme while the droplets were modeled using a Lagrangian method. The airborne droplet number, the rate at which droplets are removed, and the rate at which droplets accumulate were calculated. A larger HEPA flow rate increased the droplet removal efficiency, with most of the droplets settling on boundary surfaces. Of particular note, the air purifier location within the room had a significant impact on reducing the droplet exchange between two occupants and improving the droplet elimination efficiency.","PeriodicalId":20597,"journal":{"name":"Processes","volume":"60 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gas turbine engines have several advantages over piston reciprocating engines, such as higher output per unit volume, reduced vibration, rapid acceleration and deceleration, high power output, and clean exhaust gases. As a result, their use for propulsion in ships has been steadily increasing. However, gas turbine engines exhibit significant parameter variations depending on the rotational speed, making the design of controllers to ensure system stability while achieving satisfactory control performance, a very challenging task. In this paper, a novel CEM-based 2-DOF PID controller design technique is proposed to ensure the stability of a gas turbine engine while improving tracking and disturbance rejection performance. The proposed controller consists of a PID controller focused on enhancing disturbance rejection performance and a set-point filter to improve tracking performance. The set-point filter is composed of gains from the controller and a single weighting factor. When tuning the gains of the controller, the maximum sensitivity is considered to maintain an appropriate balance between system stability and response performance. The key novelty of this study can be summarized in two main points. One is that the controller is designed by matching characteristic equations, and by setting the roots of the desired characteristic equation as multipoles, the gains of the PID controller can be tuned with only one adjusting variable, making the tuning of the 2-DOF controller easier. The other is that the controller parameters are tuned based on maximum sensitivity, thus taking into account the robust stability of the control system. To demonstrate the feasibility of the proposed method, simulations are conducted for four scenarios using various performance indices.
{"title":"A Novel CEM-Based 2-DOF PID Controller for Low-Pressure Turbine Speed Control of Marine Gas Turbine Engines","authors":"Gun-Baek So","doi":"10.3390/pr12091916","DOIUrl":"https://doi.org/10.3390/pr12091916","url":null,"abstract":"Gas turbine engines have several advantages over piston reciprocating engines, such as higher output per unit volume, reduced vibration, rapid acceleration and deceleration, high power output, and clean exhaust gases. As a result, their use for propulsion in ships has been steadily increasing. However, gas turbine engines exhibit significant parameter variations depending on the rotational speed, making the design of controllers to ensure system stability while achieving satisfactory control performance, a very challenging task. In this paper, a novel CEM-based 2-DOF PID controller design technique is proposed to ensure the stability of a gas turbine engine while improving tracking and disturbance rejection performance. The proposed controller consists of a PID controller focused on enhancing disturbance rejection performance and a set-point filter to improve tracking performance. The set-point filter is composed of gains from the controller and a single weighting factor. When tuning the gains of the controller, the maximum sensitivity is considered to maintain an appropriate balance between system stability and response performance. The key novelty of this study can be summarized in two main points. One is that the controller is designed by matching characteristic equations, and by setting the roots of the desired characteristic equation as multipoles, the gains of the PID controller can be tuned with only one adjusting variable, making the tuning of the 2-DOF controller easier. The other is that the controller parameters are tuned based on maximum sensitivity, thus taking into account the robust stability of the control system. To demonstrate the feasibility of the proposed method, simulations are conducted for four scenarios using various performance indices.","PeriodicalId":20597,"journal":{"name":"Processes","volume":"12 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142188076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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