The concept of the carbon cycle in the old goaf of a coal mine based on CO_(2)utilization and storage was put forward adhering to the principle of low-carbon development,utilization of space resources in old goafs,and...The concept of the carbon cycle in the old goaf of a coal mine based on CO_(2)utilization and storage was put forward adhering to the principle of low-carbon development,utilization of space resources in old goafs,and associated gas resources development.Firstly,the evolution characteristics of overburden fissures in the goaf of the case was studied using a two-dimensional physical similarity simulation test,the sealing performance of the caprocks after stabilization was analyzed,and the fissures were counted and classi-fied.Then,the process of gaseous CO_(2)injection in the connected fissure was simulated by Ansys Fluent software,and the migration law and distribution characteristics of CO_(2)under the condition of gaseous CO_(2)injection were analyzed.Finally,the estimation models of free CO_(2)storage capacity in the old goaf were constructed considering the proportion of connected fissure and the effectiveness of CO_(2)injection.The CO_(2)storage capacity in the old goaf of the case coal mine was estimated.The results showed that a caprock group of“hard-thickness low-permeability hard-thickness”was formed after the caprock-fissures system in the goaf of the case tended to be stable vertically.The connected fissure,occlude cracks,and micro-fractures in the goaf accounted for 85.5%,8.5%,and 6%of the total fissures,respectively.Gaseous CO_(2)first migrated to the bottom of the connected fissure after CO_(2)was injected into the goaf,then spread horizontally along the bottom of the connected fissure after reaching the bottom,and finally spread longitudinally after filling the bottom of the entire connected fissure.The theoretical and effective storage capacities of free CO_(2)at normal temperature and pressure in the old goaf of the case were 9757 and 7477 t,respectively.The effective storage capacity of free CO_(2)at normal temperature and pressure in the old goaf after all minefield mined was 193404 t.The research can provide some reference for the coal mining industry to help the goal of“carbon peaking and carbon neutrality”.展开更多
The energy industry faces a significant challenge in extracting natural gas from offshore natural gas hydrate(NGH)reservoirs,primarily due to the low productivity of wells and the high operational costs involved.The p...The energy industry faces a significant challenge in extracting natural gas from offshore natural gas hydrate(NGH)reservoirs,primarily due to the low productivity of wells and the high operational costs involved.The present study offers an assessment of the feasibility of utilizing geothermal energy to augment the production of natural gas from offshore gas hydrate reservoirs through the implementation of the methane-CO_(2)swapping technique.The present study expands the research scope of the authors beyond their previous publication,which exclusively examined the generation of methane from marine gas hydrates.Specifically,the current investigation explores the feasibility of utilizing the void spaces created by the extracted methane in the hydrate reservoir for carbon dioxide storage.Analytical models were employed to forecast the heat transfer from a geothermal zone to an NGH reservoir.A study was conducted utilizing data obtained from a reservoir situated in the Shenhu region of the Northern South China Sea.The findings of the model indicate that the implementation of geothermal heating can lead to a substantial enhancement in the productivity of wells located in heated reservoirs during CO_(2)swapping procedures.The non-linear relationship between the temperature of the heated reservoir and the rate of fold increase has been observed.It is anticipated that the fold of increase will surpass 5 when the gas hydrate reservoir undergoes a temperature rise from 6℃ to 16℃.The mathematical models utilized in this study did not incorporate the impact of heat convection resulting from CO_(2)flow into the gas reservoir.This factor has the potential to enhance well productivity.The mathematical models’deviation assumptions may cause over-prediction of well productivity in geothermal-stimulated reservoirs.Additional research is required to examine the impacts of temperature drawdown,heat convection resulting from depressurization,heat-induced gas pressure increment,and the presence of free gas in the formation containing hydrates.The process of CH4-CO_(2)swapping,which has been investigated,involves the utilization of geothermal stimulation.This method is highly encouraging as it enables the efficient injection of CO_(2)into gas hydrate reservoirs,resulting in the permanent sequestration of CO_(2)in a solid state.Additional research is warranted to examine the rate of mass transfer of CO_(2)within reservoirs of gas hydrates.展开更多
相较于传统车载充电系统,集成型车载充电系统(integrated onboard charger system,IOCS)在成本、功率密度等方面具备显著优势。文中基于六相永磁电驱系统设计了一台IOCS,并研究了模型预测电流控制(model predictive current control,MP...相较于传统车载充电系统,集成型车载充电系统(integrated onboard charger system,IOCS)在成本、功率密度等方面具备显著优势。文中基于六相永磁电驱系统设计了一台IOCS,并研究了模型预测电流控制(model predictive current control,MPCC)算法在该系统并网模式下的应用。首先,分析所提IOCS的电路拓扑并建立数学模型,同时介绍传统MPCC的实施流程。然后,针对传统MPCC计算量大、稳态性能差等不足,提出一种基于占空比优化的MPCC(MPCC based on duty cycle optimization,DCO-MPCC)策略。一方面,减少备选电压矢量数量,降低电流预测环节带来的计算负担;另一方面,提出一种占空比优化技术,改善系统稳态性能。最后,通过实验验证了所提算法的有效性与优越性。实验结果表明,DCO-MPCC策略能够显著提升系统稳态性能并减少算法计算量。充电与车网互动(vehicle to grid,V2G)工况下,网侧电流总谐波畸变(total harmonic distortion,THD)分别降低6.18%与5.92%,算法运行时间减少17.54μs。展开更多
Sponsored by college of chemistry and molecular engineering, Peking University and Thermo Fisher Scientific, The Asian Regional Conference on 2DCOS （2DCOS-2014） was held （19, April, 2014 - 20, April, 2014） at the ...Sponsored by college of chemistry and molecular engineering, Peking University and Thermo Fisher Scientific, The Asian Regional Conference on 2DCOS （2DCOS-2014） was held （19, April, 2014 - 20, April, 2014） at the beautiful campus of Peking University. Prof. lsao Noda,展开更多
Permeability of coal reservoirs in China is in general low. Injection of CO2 into coal seams is one of the potential ap-proaches for enhancing coalbed methane (CBM) production. The feasibility of this technology has b...Permeability of coal reservoirs in China is in general low. Injection of CO2 into coal seams is one of the potential ap-proaches for enhancing coalbed methane (CBM) production. The feasibility of this technology has been investigated in China since the 1990s. Advances in mechanism of CO2 enhanced CBM recovery (CO2-ECBM) in China are reviewed in light of certain aspects, such as the competitive multi-component gas adsorption, sorption-induced coal swelling/shrinkage and its potential effect on CBM production and numerical simulation for CO2-ECBM recovery. Newer investigations for improving the technology are discussed. It is suggested that a comprehensive feasibility demonstration in terms of geology, technology, economics and environment-carrying capacity is necessary for a successful application of the technology for CBM recovery in China. The demonstration should be car-ried out after more investigations into such facets as the control of coal components and structure to a competitive multi-component-gas adsorption, the behavior and essence of super-critical adsorption by coal of gas, environmental and safe feasi-bility of coal mining after CO2 injection and more extensive pilot tests for CO2-ECBM recovery.展开更多
Since September 2011,A 2/O-MBR wastewater treatment plant in Xi'an Siyuan University has been successfully running without replacing any of membrane modules.A total of 6.661 million m^3 of campus wastewater has be...Since September 2011,A 2/O-MBR wastewater treatment plant in Xi'an Siyuan University has been successfully running without replacing any of membrane modules.A total of 6.661 million m^3 of campus wastewater has been treated,and 4.405 million m^3 of water reaching the national urban miscellaneous water standard has been reclaimed and reused.A total of 25 km pipeline,5 pits,scenery fountains,lakes,and 12 pump stations have been constructed for flushing toilets,irrigating green grass lawn and afforest,and cleaning hardened pavement.The design and construction of 5 pits,scenery fountains,and lakes are important to meet the national urban miscellaneous water standard under occasional phosphorus and/or nitrogen exceed concentration.The unit water cost is 4.19 yuan/m^3,including membrane modules depreciation and amortization.After the A 2/O-MBR system passes the membrane modules depreciation and amortization period,the unit water cost is 2.82 yuan/m^3.The water productivity of the membrane stack rises first at the beginning of operation,reaches the maximum value,and then decreases.The average annual transmembrane pressure difference increases by 1.12 kPa.The average VMD of industrial permeability decreases annually by 0.45 m^3.展开更多
A number of useful techniques associated with two-dimensional correlation spectroscopy(2DCOS)to improve its performance and utility have been developed in the last 30years.Evolution of these 2DCOS techniques,including...A number of useful techniques associated with two-dimensional correlation spectroscopy(2DCOS)to improve its performance and utility have been developed in the last 30years.Evolution of these 2DCOS techniques,including some of the very recent developments,is reviewed with examples.Topics include merged or modified asynchronous 2Dcorrelation spectrum,two-dimensional codistribution spectroscopy(2DCDS),Pareto scaling,and null-space projection treatment of spectral dataset.展开更多
基金the financial support from the National Natural Science Foundation of China(No.52074217)the Natural Science Basic Research Program of Shaanxi Province(No.2021JLM-26).
文摘The concept of the carbon cycle in the old goaf of a coal mine based on CO_(2)utilization and storage was put forward adhering to the principle of low-carbon development,utilization of space resources in old goafs,and associated gas resources development.Firstly,the evolution characteristics of overburden fissures in the goaf of the case was studied using a two-dimensional physical similarity simulation test,the sealing performance of the caprocks after stabilization was analyzed,and the fissures were counted and classi-fied.Then,the process of gaseous CO_(2)injection in the connected fissure was simulated by Ansys Fluent software,and the migration law and distribution characteristics of CO_(2)under the condition of gaseous CO_(2)injection were analyzed.Finally,the estimation models of free CO_(2)storage capacity in the old goaf were constructed considering the proportion of connected fissure and the effectiveness of CO_(2)injection.The CO_(2)storage capacity in the old goaf of the case coal mine was estimated.The results showed that a caprock group of“hard-thickness low-permeability hard-thickness”was formed after the caprock-fissures system in the goaf of the case tended to be stable vertically.The connected fissure,occlude cracks,and micro-fractures in the goaf accounted for 85.5%,8.5%,and 6%of the total fissures,respectively.Gaseous CO_(2)first migrated to the bottom of the connected fissure after CO_(2)was injected into the goaf,then spread horizontally along the bottom of the connected fissure after reaching the bottom,and finally spread longitudinally after filling the bottom of the entire connected fissure.The theoretical and effective storage capacities of free CO_(2)at normal temperature and pressure in the old goaf of the case were 9757 and 7477 t,respectively.The effective storage capacity of free CO_(2)at normal temperature and pressure in the old goaf after all minefield mined was 193404 t.The research can provide some reference for the coal mining industry to help the goal of“carbon peaking and carbon neutrality”.
基金funding the project“Safe,Sustainable,and Resilient Development of Offshore Reservoirs and Natural Gas Upgrading through Innovative Science and Technology:Gulf of Mexico–Mediterranean,”through Contract No.EC-19 Fossil Energy。
文摘The energy industry faces a significant challenge in extracting natural gas from offshore natural gas hydrate(NGH)reservoirs,primarily due to the low productivity of wells and the high operational costs involved.The present study offers an assessment of the feasibility of utilizing geothermal energy to augment the production of natural gas from offshore gas hydrate reservoirs through the implementation of the methane-CO_(2)swapping technique.The present study expands the research scope of the authors beyond their previous publication,which exclusively examined the generation of methane from marine gas hydrates.Specifically,the current investigation explores the feasibility of utilizing the void spaces created by the extracted methane in the hydrate reservoir for carbon dioxide storage.Analytical models were employed to forecast the heat transfer from a geothermal zone to an NGH reservoir.A study was conducted utilizing data obtained from a reservoir situated in the Shenhu region of the Northern South China Sea.The findings of the model indicate that the implementation of geothermal heating can lead to a substantial enhancement in the productivity of wells located in heated reservoirs during CO_(2)swapping procedures.The non-linear relationship between the temperature of the heated reservoir and the rate of fold increase has been observed.It is anticipated that the fold of increase will surpass 5 when the gas hydrate reservoir undergoes a temperature rise from 6℃ to 16℃.The mathematical models utilized in this study did not incorporate the impact of heat convection resulting from CO_(2)flow into the gas reservoir.This factor has the potential to enhance well productivity.The mathematical models’deviation assumptions may cause over-prediction of well productivity in geothermal-stimulated reservoirs.Additional research is required to examine the impacts of temperature drawdown,heat convection resulting from depressurization,heat-induced gas pressure increment,and the presence of free gas in the formation containing hydrates.The process of CH4-CO_(2)swapping,which has been investigated,involves the utilization of geothermal stimulation.This method is highly encouraging as it enables the efficient injection of CO_(2)into gas hydrate reservoirs,resulting in the permanent sequestration of CO_(2)in a solid state.Additional research is warranted to examine the rate of mass transfer of CO_(2)within reservoirs of gas hydrates.
文摘相较于传统车载充电系统,集成型车载充电系统(integrated onboard charger system,IOCS)在成本、功率密度等方面具备显著优势。文中基于六相永磁电驱系统设计了一台IOCS,并研究了模型预测电流控制(model predictive current control,MPCC)算法在该系统并网模式下的应用。首先,分析所提IOCS的电路拓扑并建立数学模型,同时介绍传统MPCC的实施流程。然后,针对传统MPCC计算量大、稳态性能差等不足,提出一种基于占空比优化的MPCC(MPCC based on duty cycle optimization,DCO-MPCC)策略。一方面,减少备选电压矢量数量,降低电流预测环节带来的计算负担;另一方面,提出一种占空比优化技术,改善系统稳态性能。最后,通过实验验证了所提算法的有效性与优越性。实验结果表明,DCO-MPCC策略能够显著提升系统稳态性能并减少算法计算量。充电与车网互动(vehicle to grid,V2G)工况下,网侧电流总谐波畸变(total harmonic distortion,THD)分别降低6.18%与5.92%,算法运行时间减少17.54μs。
文摘Sponsored by college of chemistry and molecular engineering, Peking University and Thermo Fisher Scientific, The Asian Regional Conference on 2DCOS （2DCOS-2014） was held （19, April, 2014 - 20, April, 2014） at the beautiful campus of Peking University. Prof. lsao Noda,
基金Projects 40730422 supported by the National Natural Science Foundation of China2006AA06Z231 by the Hi-tech Research and Development Program of Chinapart of a Sino-Aus-tralian special joint project of science and technology(407112365)
文摘Permeability of coal reservoirs in China is in general low. Injection of CO2 into coal seams is one of the potential ap-proaches for enhancing coalbed methane (CBM) production. The feasibility of this technology has been investigated in China since the 1990s. Advances in mechanism of CO2 enhanced CBM recovery (CO2-ECBM) in China are reviewed in light of certain aspects, such as the competitive multi-component gas adsorption, sorption-induced coal swelling/shrinkage and its potential effect on CBM production and numerical simulation for CO2-ECBM recovery. Newer investigations for improving the technology are discussed. It is suggested that a comprehensive feasibility demonstration in terms of geology, technology, economics and environment-carrying capacity is necessary for a successful application of the technology for CBM recovery in China. The demonstration should be car-ried out after more investigations into such facets as the control of coal components and structure to a competitive multi-component-gas adsorption, the behavior and essence of super-critical adsorption by coal of gas, environmental and safe feasi-bility of coal mining after CO2 injection and more extensive pilot tests for CO2-ECBM recovery.
文摘Since September 2011,A 2/O-MBR wastewater treatment plant in Xi'an Siyuan University has been successfully running without replacing any of membrane modules.A total of 6.661 million m^3 of campus wastewater has been treated,and 4.405 million m^3 of water reaching the national urban miscellaneous water standard has been reclaimed and reused.A total of 25 km pipeline,5 pits,scenery fountains,lakes,and 12 pump stations have been constructed for flushing toilets,irrigating green grass lawn and afforest,and cleaning hardened pavement.The design and construction of 5 pits,scenery fountains,and lakes are important to meet the national urban miscellaneous water standard under occasional phosphorus and/or nitrogen exceed concentration.The unit water cost is 4.19 yuan/m^3,including membrane modules depreciation and amortization.After the A 2/O-MBR system passes the membrane modules depreciation and amortization period,the unit water cost is 2.82 yuan/m^3.The water productivity of the membrane stack rises first at the beginning of operation,reaches the maximum value,and then decreases.The average annual transmembrane pressure difference increases by 1.12 kPa.The average VMD of industrial permeability decreases annually by 0.45 m^3.
文摘A number of useful techniques associated with two-dimensional correlation spectroscopy(2DCOS)to improve its performance and utility have been developed in the last 30years.Evolution of these 2DCOS techniques,including some of the very recent developments,is reviewed with examples.Topics include merged or modified asynchronous 2Dcorrelation spectrum,two-dimensional codistribution spectroscopy(2DCDS),Pareto scaling,and null-space projection treatment of spectral dataset.
