The energy-saving electrohydraulic flow matching （EFM） system opens up an opportunity to minimize valve losses by fully opening the control valves, but the controllability is lost under overrunning load conditions. ...The energy-saving electrohydraulic flow matching （EFM） system opens up an opportunity to minimize valve losses by fully opening the control valves, but the controllability is lost under overrunning load conditions. To address this issue, this paper proposes a valve-based compensator to improve the controllability of the energy-saving EFM system. The valve-based compensator consists of a static compensator and a differential dynamic compensator based on load conditions. The energy effi- ciency, the stability performance, and the damping characteristic are analyzed under different control parameters. A parameter selection method is used to improve the efficiency, ensure the stability performance, and obtain good dynamic behavior. A test rig with a 2-t hydraulic excavator is built, and experimental tests are carried out to validate the proposed valve-based compensator. The experimental results indicate that the controllability of the EFM system is improved, and the characteristic of high energy efficiency is obtained by the proposed compensator.展开更多
A heavy-duty gas turbine,designed for natural gas,was used to bum the syngas with two different calorific values.This study was mainly to optimize the flow matching scheme for the gas turbine.Two models of gas turbine...A heavy-duty gas turbine,designed for natural gas,was used to bum the syngas with two different calorific values.This study was mainly to optimize the flow matching scheme for the gas turbine.Two models of gas turbine burning syngas with different calorific values were established and the calculation models of different flow matching schemes were provided.The optimum scheme was obtained by evaluating thermal efficiency and work output under different operating conditions.The results showed that the highest unit efficiency was achieved by,without significant drop in work output,increasing the throat area of the turbine nozzle and reducing the initial temperature of the gas.On the premise of ensuring the safety of the gas turbine unit,increasing the pressure ratio of the compressor could further improve the unit efficiency and the work output.Simply adjusting the angle of the inlet guide vane fails to match the flow of compressor and turbine.The measures such as reducing inlet temperature of turbine or air bleed still need to be adopted,but the thermal efficiency dropped significantly in this process.展开更多
The BZ19-6 gas field is characterized by high temperature and high pressure (HTHP), high condensate content, little difference between the formation pressure and dew point pressure, and large amount of reverse condens...The BZ19-6 gas field is characterized by high temperature and high pressure (HTHP), high condensate content, little difference between the formation pressure and dew point pressure, and large amount of reverse condensate liquid. During the early stage of depletion development, the production gas-oil ratio (GOR) and production capacity remain relatively stable, which is inconsistent with the conventional reverse condensate seepage law. In view of the static and dynamic conflict in development and production, indoor high-temperature and high-pressure PVT experiment was carried out to reveal the mist-like condensation phenomenon of fluids in the BZ19-6 formation. And the seepage characteristics of condensate gas reservoirs with various degrees of depletion under the condition of HTHP were analyzed based on production performance. The change rule of fluid phase state was analyzed in response to the characterization difficulties of the seepage mechanism. The fluid state was described using the miscible mechanism. And the interphase permeability interpolation coefficient was introduced based on interfacial tension. By doing so, the accurate characterization of the “single-phase flow of condensate gas-near-miscible mist-like quasi single-phase flow-oil-gas two-phase flow” during the development process was achieved. Then the accurate fitting of key indicators for oilfield development was completed, and the distribution law of formation pressure and the law of condensate oil precipitation under different reservoir conditions are obtained. Based on research results, the regulation strategy of variable flow rate production was developed. Currently, the work system has been optimized for 11 wells, achieving a “zero increase” in the GOS of the gas field and an annual oil increase of 22,000 cubic meters.展开更多
激发创新主体活力,是知识经济时代提升国家创新体系整体效能和建设世界科技强国的重要内容。学术人才流动作为高校间人才竞争的表现形式,能否带来基础研究创新产出的提升以及相应的作用机制尚待明确。基于Web of Science数据库2008—201...激发创新主体活力,是知识经济时代提升国家创新体系整体效能和建设世界科技强国的重要内容。学术人才流动作为高校间人才竞争的表现形式,能否带来基础研究创新产出的提升以及相应的作用机制尚待明确。基于Web of Science数据库2008—2018年中国高校发表的论文数据,使用固定效应模型和工具变量方法从学术人才流动的视角回答如何提升基础研究科研效率这一问题。研究发现,高校人才流动能够促进知识溢出,从而提升高校基础研究产出效率。机制分析表明,高校之间的人才流动通过研究人员合作论文数量的增加以及流入学者与高校之间更好的匹配来实现高校科研效率的提升。异质性分析表明,高校人才流入对基础研究创新产出的影响在社会科学领域以及人才流向东部高校中更为显著。研究结论为现阶段如何提升基础研究产出效率、释放学术人才红利提供参考。展开更多
基金Project supported by the National Natural Science Foundation of China （No. 51375431）, the Open Fund of the State Key Laboratory of Fluid Power and Mechatronic Systems （No. GZKF-201503）, and the Research Fund of the State Key Laboratory of Mechanical Transmission （No. SKLMT-ZZKT-2015Z10）, China
文摘The energy-saving electrohydraulic flow matching （EFM） system opens up an opportunity to minimize valve losses by fully opening the control valves, but the controllability is lost under overrunning load conditions. To address this issue, this paper proposes a valve-based compensator to improve the controllability of the energy-saving EFM system. The valve-based compensator consists of a static compensator and a differential dynamic compensator based on load conditions. The energy effi- ciency, the stability performance, and the damping characteristic are analyzed under different control parameters. A parameter selection method is used to improve the efficiency, ensure the stability performance, and obtain good dynamic behavior. A test rig with a 2-t hydraulic excavator is built, and experimental tests are carried out to validate the proposed valve-based compensator. The experimental results indicate that the controllability of the EFM system is improved, and the characteristic of high energy efficiency is obtained by the proposed compensator.
基金This work was support by the National Natural Science Foundation of China(Grant No.51976214 and No.51576193)National Science and Technology Major Project(2017-V-0010-0001 and 2017-IV-0100-0047).
文摘A heavy-duty gas turbine,designed for natural gas,was used to bum the syngas with two different calorific values.This study was mainly to optimize the flow matching scheme for the gas turbine.Two models of gas turbine burning syngas with different calorific values were established and the calculation models of different flow matching schemes were provided.The optimum scheme was obtained by evaluating thermal efficiency and work output under different operating conditions.The results showed that the highest unit efficiency was achieved by,without significant drop in work output,increasing the throat area of the turbine nozzle and reducing the initial temperature of the gas.On the premise of ensuring the safety of the gas turbine unit,increasing the pressure ratio of the compressor could further improve the unit efficiency and the work output.Simply adjusting the angle of the inlet guide vane fails to match the flow of compressor and turbine.The measures such as reducing inlet temperature of turbine or air bleed still need to be adopted,but the thermal efficiency dropped significantly in this process.
文摘The BZ19-6 gas field is characterized by high temperature and high pressure (HTHP), high condensate content, little difference between the formation pressure and dew point pressure, and large amount of reverse condensate liquid. During the early stage of depletion development, the production gas-oil ratio (GOR) and production capacity remain relatively stable, which is inconsistent with the conventional reverse condensate seepage law. In view of the static and dynamic conflict in development and production, indoor high-temperature and high-pressure PVT experiment was carried out to reveal the mist-like condensation phenomenon of fluids in the BZ19-6 formation. And the seepage characteristics of condensate gas reservoirs with various degrees of depletion under the condition of HTHP were analyzed based on production performance. The change rule of fluid phase state was analyzed in response to the characterization difficulties of the seepage mechanism. The fluid state was described using the miscible mechanism. And the interphase permeability interpolation coefficient was introduced based on interfacial tension. By doing so, the accurate characterization of the “single-phase flow of condensate gas-near-miscible mist-like quasi single-phase flow-oil-gas two-phase flow” during the development process was achieved. Then the accurate fitting of key indicators for oilfield development was completed, and the distribution law of formation pressure and the law of condensate oil precipitation under different reservoir conditions are obtained. Based on research results, the regulation strategy of variable flow rate production was developed. Currently, the work system has been optimized for 11 wells, achieving a “zero increase” in the GOS of the gas field and an annual oil increase of 22,000 cubic meters.
文摘激发创新主体活力,是知识经济时代提升国家创新体系整体效能和建设世界科技强国的重要内容。学术人才流动作为高校间人才竞争的表现形式,能否带来基础研究创新产出的提升以及相应的作用机制尚待明确。基于Web of Science数据库2008—2018年中国高校发表的论文数据,使用固定效应模型和工具变量方法从学术人才流动的视角回答如何提升基础研究科研效率这一问题。研究发现,高校人才流动能够促进知识溢出,从而提升高校基础研究产出效率。机制分析表明,高校之间的人才流动通过研究人员合作论文数量的增加以及流入学者与高校之间更好的匹配来实现高校科研效率的提升。异质性分析表明,高校人才流入对基础研究创新产出的影响在社会科学领域以及人才流向东部高校中更为显著。研究结论为现阶段如何提升基础研究产出效率、释放学术人才红利提供参考。
