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Performance of a bi-layer solar steam generation system working at a high-temperature of top surface

Jinxin ZHONG, Congliang HUANG

《能源前沿(英文)》 2023年 第17卷 第1期   页码 141-148 doi: 10.1007/s11708-021-0725-4

摘要: Many efforts have been focused on enhancing the vapor generation in bi-layer solar steam generation systems for obtaining as much pure water as possible. However, the methods to enhance the vapor temperature is seldom studied although the high-temperature vapor has a wide use in medical sterilization and electricity generation. In this work, to probe the high-temperature vapor system, an improved macroscopic heat and mass transfer model was proposed. Then, using the finite element method to solve the model, the influences of some main factors on the evaporation efficiency and vapor temperature were discussed, including effects of the vapor transport conditions and the heat dissipation conditions. The results show that the high-temperature vapor could not be obtained by enhancing the heat-insulating property of the bi-layer systems but by applying the optimal porosity and proper absorbers. This paper is expected to provide some information for designing a bi-layered system to produce high-temperature vapor.

关键词: solar steam generation     solar energy     numerical method     porous material    

Characteristics Analysis of Integrated CAES and CFPP Trigeneration System Considering Working Conditions

Jiajia Li,Peigang Yan,Guowen Zhou,Xingshuo Li,Qiang Li,Jinfu Liu,Daren Yu,

《工程(英文)》 doi: 10.1016/j.eng.2023.06.015

摘要: To meet the goal of worldwide decarbonization, the transformation process toward clean and green energy structures has accelerated. In this context, coal-fired power plant (CFPPs) and large-scale energy storage represented by compressed air energy storage (CAES) technology, are tasked with increasing renewable resource accommodation and maintaining the power system security. To achieve this, this paper proposes the concept of a CFPP–CAES combined cycle and a trigenerative system based on that. Considering the working conditions of the CFPP, thermal characteristics of three typical operation modes were studied and some general regularities were identified. The results of various potential integration schemes discussion indicated that extracting water from low-temperature points in the feedwater system to cool pressurized air and simultaneously increase the backwater temperature is beneficial for improving performance. In addition, preheating the pressurized air before the air expanders via low-grade water in the feedwater system as much as possible and reducing extracted steam contribute to increasing the efficiency. With the optimal integration scheme, 2.85 tonnes of coal can be saved per cycle and the round-trip efficiency can be increased by 2.24%. Through the cogeneration of heat and power, the system efficiency can reach 77.5%. In addition, the contribution degree of the three compression heat utilization methods to the performance improvement ranked from high to low, is preheating the feedwater before the boiler, supplying heat, and flowing into the CFPP feedwater system. In the cooling energy generation mode, the system efficiency can be increased to over 69%. Regardless of the operation mode, the benefit produced by integration is further enhanced when the CFPP operates at higher operating conditions because the coupling points parameters are changed. In addition, the dynamic payback period can be shortened by 11.33 years and the internal rate of return increases by 5.20% under a typical application scenario. Regarding the effect of different application scenarios in terms of economics, investing in the proposed system is more appropriate in regions with multiple energy demands, especially heating demand. These results demonstrate the technical advantages of the proposed system and provide guiding principles for its design, operation, and project investment.

关键词: Compressed air energy storage     CFPP–CAES combined cycle     Thermodynamic performance     Technical economics    

Effects of thermocline on performance of underwater glider’s power system propelled by ocean thermal

Hai YANG, Jie MA,

《能源前沿(英文)》 2009年 第3卷 第4期   页码 472-479 doi: 10.1007/s11708-009-0052-7

摘要: The thermal glider’s changeable volume produces propelling force to power the glider’s descending and ascending through the thermocline. The different depth, thickness, and intensity of the thermocline at different seasons and locations affect the working processes of the glider’s power system. Based on the enthalpy method, a mathematical model of the underwater glider’s power system was established and the time efficiency of operation was introduced, so that the effects of different thermoclines on the underwater glider’s power system were analyzed theoretically. The simulation result shows that the thermocline affects the transition time of the phase change processes of working fluids within the thermal engine tubes. There exist the threshold values of the thermocline’s depth and upper thickness for the power system’s operation. A depth or upper thickness of the thermocline less than the corresponding threshold leads the power system to work abnormally. To keep the power system working efficiently, a glider must be kept in warm surface water for a certain period before it moves through cold water, so that the time efficiency of operation is reduced. A less time efficiency of operation is unfavorable to the thermal glider to penetrate through the ocean currents.

关键词: mathematical     underwater glider     system working     certain     corresponding threshold    

Performance design of a cryogenic air separation unit for variable working conditions using the lumped

Jinghua XU, Tiantian WANG, Qianyong CHEN, Shuyou ZHANG, Jianrong TAN

《机械工程前沿(英文)》 2020年 第15卷 第1期   页码 24-42 doi: 10.1007/s11465-019-0558-6

摘要: Large-scale cryogenic air separation units (ASUs), which are widely used in global petrochemical and semiconductor industries, are being developed with high operating elasticity under variable working conditions. Different from discrete processes in traditional machinery manufacturing, the ASU process is continuous and involves the compression, adsorption, cooling, condensation, liquefaction, evaporation, and distillation of multiple streams. This feature indicates that thousands of technical parameters in adsorption, heat transfer, and distillation processes are correlated and merged into a large-scale complex system. A lumped parameter model (LPM) of ASU is proposed by lumping the main factors together and simplifying the secondary ones to achieve accurate and fast performance design. On the basis of material and energy conservation laws, the piecewise-lumped parameters are extracted under variable working conditions by using LPM. Takagi–Sugeno (T–S) fuzzy interval detection is recursively utilized to determine whether the critical point is detected or not by using different thresholds. Compared with the traditional method, LPM is particularly suitable for “rough first then precise” modeling by expanding the feasible domain using fuzzy intervals. With LPM, the performance of the air compressor, molecular sieve adsorber, turbo expander, main plate-fin heat exchangers, and packing column of a 100000 Nm O /h large-scale ASU is enhanced to adapt to variable working conditions. The designed value of net power consumption per unit of oxygen production (kW/(Nm O )) is reduced by 6.45%.

关键词: performance design     air separation unit (ASU)     lumped parameter model (LPM)     variable working conditions     T–S fuzzy interval detection    

液压冲击机构工作参数调节机理与控制策略S

刘忠,,褚福磊,龙国键,廖永忠

《中国工程科学》 2005年 第7卷 第10期   页码 73-77

摘要:

针对目前国内外液压冲击机械工作参数调节方法的局限性,提出了行程无级调节原理,设计了一种新型的行程无级调节装置,并对该装置进行了数字仿真研究;在此基础上设计了一种基于微机控制的无级调节工作参数的液压冲击机构,论述了其设计原理、结构特点、技术性能和控制策略。

关键词: 液压冲击机构     无级调节     工作参数     控制系统    

Two-level uncapacitated lot-sizing problem considering the financing cost of working capital requirement

Yuan BIAN, David LEMOINE, Thomas G. YEUNG, Nathalie BOSTEL

《工程管理前沿(英文)》 2020年 第7卷 第2期   页码 248-258 doi: 10.1007/s42524-019-0069-5

摘要: During financial crisis, companies constantly need free cash flows to efficiently react to any uncertainty, thus ensuring solvency. Working capital requirement (WCR) has been recognized as a key factor for releasing tied up cash in companies. However, in literatures related to lot-sizing problem, WCR has only been studied in the single-level supply chain context. In this paper, we initially adopt WCR model for a multi-level case. A two-level (supplier–customer) model is established on the basis of the classic multi-level lot-sizing model integrated with WCR financing cost. To tackle this problem, we propose sequential and centralized approaches to solve the two-level case with a serial chain structure. The ZIO (Zero Inventory Ordering) property is further confirmed valid in both cases. This property allows us to establish a dynamic programming-based algorithm, which solves the problem in O(T ). Finally, numerical tests show differences in optimal plans obtained by both approaches and the influence of varying delays in payment on the WCR of both actors.

关键词: two-level ULS problem     lot-sizing     working capital requirement     ZIO property     infinite production capacity    

A method to calculate working capacity space of multi-DOF manipulator and the application in excavating

Baochen WEI, Feng GAO

《机械工程前沿(英文)》 2012年 第7卷 第2期   页码 109-119 doi: 10.1007/s11465-012-0323-6

摘要:

Working capacity refers to the velocity output and force output of a manipulator. It is usually be represented by output capacity space. In this paper, the method of Linear Programming and a geometric method are proposed to calculate working capacity spaces in different situations. With the consideration of gravity effect of every component, the output force capacity space of heavy duty manipulators is calculated. The results show that the effect of the gravity is a translation of the capacity space. This paper gives a method for the output capacity express especially for heavy duty manipulators. The output capacity space can be helpful to the driving parameters selection. With the consideration of the gravity effect of every component and the friction at the joints, the excavating force capacity space of the heavy-load excavating mechanism is calculated and is represented as a multi-dimensional polytope. The results show that the effect of the gravity and friction is to translational act on the capacity space.

关键词: working capacity     multi-DOF manipulator     capacity polytope     excavating mechanism    

Unit commitment using dynamic programming–an exhaustive working of both classical and stochastic approach

Balasubramaniyan SARAVANAN, Surbhi SIKRI, K. S. SWARUP, D. P. KOTHARI

《能源前沿(英文)》 2013年 第7卷 第3期   页码 333-341 doi: 10.1007/s11708-013-0259-5

摘要: In the present electricity market, where renewable energy power plants have been included in the power systems, there is a lot of unpredictability in the demand and generation. There are many conventional and evolutionary programming techniques used for solving the unit commitment (UC) problem. Dynamic programming (DP) is a conventional algorithm used to solve the deterministic problem. In this paper DP is used to solve the stochastic model of UC problem. The stochastic modeling for load and generation side has been formulated using an approximate state decision approach. The programs were developed in a MATLAB environment and were extensively tested for a four-unit eight-hour system. The results obtained from these techniques were validated with the available literature and outcome was good. The commitment is in such a way that the total cost is minimal. The novelty of this paper lies in the fact that DP is used for solving the stochastic UC problem.

关键词: unit commitment (UC)     deterministic     stochastic     dynamic programming (DP)     optimization     state diagram    

Exergy analysis of R1234ze(Z) as high temperature heat pump working fluid with multi-stage compression

Bin HU, Di WU, L.W. WANG, R.Z. WANG

《能源前沿(英文)》 2017年 第11卷 第4期   页码 493-502 doi: 10.1007/s11708-017-0510-6

摘要: In this paper, the simulation approach and exergy analysis of multi-stage compression high temperature heat pump (HTHP) systems with R1234ze(Z) working fluid are conducted. Both the single-stage and multi-stage compression cycles are analyzed to compare the system performance with 120°C pressurized hot water supply based upon waste heat recovery. The exergy destruction ratios of each component for different stage compression systems are compared. The results show that the exergy loss ratios of the compressor are bigger than that of the evaporator and the condenser for the single-stage compression system. The multi-stage compression system has better energy and exergy efficiencies with the increase of compression stage number. Compared with the single-stage compression system, the coefficient of performance (COP) improvements of the two-stage and three-stage compression system are 9.1% and 14.6%, respectively. When the waste heat source temperature is 60°C, the exergy efficiencies increase about 6.9% and 11.8% for the two-stage and three-stage compression system respectively.

关键词: multi-stage compression     high temperature heat pump     heat recovery     exergy destruction     R1234ze(Z) working fluid    

Working Up Green, and Living Up Green

Ji-shan He

《工程管理前沿(英文)》 2014年 第1卷 第1期   页码 2-2 doi: 10.15302/J-FEM-2014002

Experimental study on working parameters of earth pressure balance shield machine tunneling in soft ground

ZHU Hehua, LIAO Shaoming, XU Qianwei, ZHENG Qizhen

《结构与土木工程前沿(英文)》 2008年 第2卷 第4期   页码 350-358 doi: 10.1007/s11709-008-0051-5

摘要: Deep sedimentary deposits of soft clays are widely distributed in coastal areas as well as many interior major cities in China. In order to study the stratum adaptability of earth pressure balance (EPB) shield machine tunneling in such types of soft ground, model tests of tunneling excavation, using the running tunnel of the Shanghai Metro Line M8 as a background, are carried out with different over burden ratios, opening rates of cutter head, driving speeds and rotation speeds of screw conveyor. Based on the test results, the interrelationships between chamber pressure and mucking efficiency, mucking rate and driving speed, thrust force and torque are obtained. The influences of tunnel depth, opening rate of cutter head and driving speed on thrust force and torque are revealed. Such findings can not only facilitate establishing relationships between shield working parameters and soil properties, but also serve as a guide for the design and construction of shield tunnel in soft ground.

关键词: construction     different     coastal     conveyor     excavation    

新建有岩爆倾向硬岩矿床采矿技术研究工作程序

郭然,于润沧

《中国工程科学》 2002年 第4卷 第7期   页码 51-55

摘要:

目前矿山的岩爆研究工作大都是围绕着如何预报和防治岩爆展开的,针对如何开展新建或尚未发生过岩爆矿山的岩爆研究工作不多。文章重点探讨了新建有岩爆倾向硬岩矿床开采技术研究工作程序,为建立有岩爆倾向深赋硬岩矿床采矿理论体系奠定了基础。

关键词: 岩爆     采矿技术     工作程序    

Performance analysis of cogeneration systems based on micro gas turbine (MGT), organic Rankine cycle and ejector refrigeration cycle

Zemin BO, Kai ZHANG, Peijie SUN, Xiaojing LV, Yiwu WENG

《能源前沿(英文)》 2019年 第13卷 第1期   页码 54-63 doi: 10.1007/s11708-018-0606-7

摘要: In this paper, the operation performance of three novel kinds of cogeneration systems under design and off-design condition was investigated. The systems are MGT (micro gas turbine) + ORC (organic Rankine cycle) for electricity demand, MGT+ ERC (ejector refrigeration cycle) for electricity and cooling demand, and MGT+ ORC+ ERC for electricity and cooling demand. The effect of 5 different working fluids on cogeneration systems was studied. The results show that under the design condition, when using R600 in the bottoming cycle, the MGT+ ORC system has the lowest total output of 117.1 kW with a thermal efficiency of 0.334, and the MGT+ ERC system has the largest total output of 142.6 kW with a thermal efficiency of 0.408. For the MGT+ ORC+ ERC system, the total output is between the other two systems, which is 129.3 kW with a thermal efficiency of 0.370. For the effect of different working fluids, R123 is the most suitable working fluid for MGT+ ORC with the maximum electricity output power and R600 is the most suitable working fluid for MGT+ ERC with the maximum cooling capacity, while both R600 and R123 can make MGT+ ORC+ ERC achieve a good comprehensive performance of refrigeration and electricity. The thermal efficiency of three cogeneration systems can be effectively improved under off-design condition because the bottoming cycle can compensate for the power decrease of MGT. The results obtained in this paper can provide a reference for the design and operation of the cogeneration system for distributed energy systems (DES).

关键词: cogeneration system     different working fluids     micro gas turbine (MGT)     organic Rankine cycle (ORC)     ejector refrigeration cycle (ERC)    

工作经验对空中交通管制员眼动行为的影响 Article

王艳军, 王丽伟, 林思远, 丛玮, 薛建飞, Washington Ochieng

《工程(英文)》 2021年 第7卷 第4期   页码 488-494 doi: 10.1016/j.eng.2020.11.006

摘要:

眼动是信息搜索行为的一个重要指标,它提供了对决策至关重要的认知策略的洞察力。学者们提出了各种基于眼动的方法来捕捉人类在复杂环境中处理信息的能力。这些方法的有效性在空中交通管理领域尚未得到充分探讨。本文对不同工作经验水平的空中交通管制员的眼动测量指标进行了比较研究。研究了两种通常研究的眼动行为:注视和扫视,以及注视熵。通过比较相关指标的统计特性,发现工作经验对眼动模式有显著影响。在合格和新手管制员之间,注视和扫视都不同,前者能够采用更有效的搜索策略。这些发现不仅有助于提高管制员培训的质量,而且有助于理解人类在执行复杂任务时使用的信息搜索机制。
 

关键词: 空中交通管制     人为因素     眼动     工作经验    

Recent advances in electrochemical decontamination of perfluorinated compounds from water: a review

《环境科学与工程前沿(英文)》 2023年 第17卷 第2期 doi: 10.1007/s11783-023-1618-z

摘要:

● Recent advances in the electrochemical decontamination of PFAS are reviewed.

关键词: Perfluorinated compounds     Electrochemical approach     Working mechanisms     Impacting factor     Coupled process    

标题 作者 时间 类型 操作

Performance of a bi-layer solar steam generation system working at a high-temperature of top surface

Jinxin ZHONG, Congliang HUANG

期刊论文

Characteristics Analysis of Integrated CAES and CFPP Trigeneration System Considering Working Conditions

Jiajia Li,Peigang Yan,Guowen Zhou,Xingshuo Li,Qiang Li,Jinfu Liu,Daren Yu,

期刊论文

Effects of thermocline on performance of underwater glider’s power system propelled by ocean thermal

Hai YANG, Jie MA,

期刊论文

Performance design of a cryogenic air separation unit for variable working conditions using the lumped

Jinghua XU, Tiantian WANG, Qianyong CHEN, Shuyou ZHANG, Jianrong TAN

期刊论文

液压冲击机构工作参数调节机理与控制策略S

刘忠,,褚福磊,龙国键,廖永忠

期刊论文

Two-level uncapacitated lot-sizing problem considering the financing cost of working capital requirement

Yuan BIAN, David LEMOINE, Thomas G. YEUNG, Nathalie BOSTEL

期刊论文

A method to calculate working capacity space of multi-DOF manipulator and the application in excavating

Baochen WEI, Feng GAO

期刊论文

Unit commitment using dynamic programming–an exhaustive working of both classical and stochastic approach

Balasubramaniyan SARAVANAN, Surbhi SIKRI, K. S. SWARUP, D. P. KOTHARI

期刊论文

Exergy analysis of R1234ze(Z) as high temperature heat pump working fluid with multi-stage compression

Bin HU, Di WU, L.W. WANG, R.Z. WANG

期刊论文

Working Up Green, and Living Up Green

Ji-shan He

期刊论文

Experimental study on working parameters of earth pressure balance shield machine tunneling in soft ground

ZHU Hehua, LIAO Shaoming, XU Qianwei, ZHENG Qizhen

期刊论文

新建有岩爆倾向硬岩矿床采矿技术研究工作程序

郭然,于润沧

期刊论文

Performance analysis of cogeneration systems based on micro gas turbine (MGT), organic Rankine cycle and ejector refrigeration cycle

Zemin BO, Kai ZHANG, Peijie SUN, Xiaojing LV, Yiwu WENG

期刊论文

工作经验对空中交通管制员眼动行为的影响

王艳军, 王丽伟, 林思远, 丛玮, 薛建飞, Washington Ochieng

期刊论文

Recent advances in electrochemical decontamination of perfluorinated compounds from water: a review

期刊论文