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Effect of variable heat capacities on performance of an irreversible Miller heat engine

Xingmei YE

《能源前沿（英文）》 2012年 第6卷 第3期   页码 280-284 doi: 10.1007/s11708-012-0203-0

摘要： Based on the variable heat capacities of the working fluid, the irreversibility coming from the compression and expansion processes, and the heat leak losses through the cylinder wall, an irreversible cycle model of the Miller heat engine was established, from which expressions for the efficiency and work output of the cycle were derived. The performance characteristic curves of the Miller heat engine were generated through numerical calculation, from which the optimal regions of some main parameters such as the work output, efficiency and pressure ratio were determined. Moreover, the influence of the compression and expansion efficiencies, the variable heat capacities and the heat leak losses on the performance of the cycle was discussed in detail, and consequently, some significant results were obtained.

关键词： Miller cycle     variable heat capacity     irreversibility     parametric optimization    

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Improvement of engine performance with high compression ratio based on knock suppression using Millercycle with boost pressure and split injection

Haiqiao WEI, Jie YU, Lei ZHOU

《能源前沿（英文）》 2019年 第13卷 第4期   页码 691-706 doi: 10.1007/s11708-019-0621-3

摘要： In theory, high compression ratio has the potential to improve the thermal efficiency and promote the power output of the SI engine. However, the application of high compression ratio is substantially limited by the knock in practical working process. The objective of this work is to comprehensively investigate the application of high compression ratio on a gasoline engine based on the Miller cycle with boost pressure and split injection. In this work, the specific optimum strategies for CR10 and CR12 were experimentally investigated respectively on a single cylinder DISI engine. It was found that a high level of Miller cycle with a higher boost pressure could be used in CR12 to achieve an effective compression ratio similar to CR10, which could eliminate the knock limits at a high compression ratio and high load. To verify the advantages of the high compression ratio, the fuel economy and power performance of CR10 and CR12 were compared at full and partial loads. The result revealed that, compared with CR10, a similar power performance and a reduced fuel consumption of CR12 at full load could be achieved by using the strong Miller cycle and split injection. At partial load, the conditions of CR12 had very superior fuel economy and power performance compared to those of CR10.

关键词： high compression ratio     knock     Miller cycle     split injection     engine performance    

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Optimization of the power, efficiency and ecological function for an air-standard irreversible Dual-Millercycle

Zhixiang WU, Lingen CHEN, Yanlin GE, Fengrui SUN

《能源前沿（英文）》 2019年 第13卷 第3期   页码 579-589 doi: 10.1007/s11708-018-0557-z

摘要： This paper establishes an irreversible Dual-Miller cycle (DMC) model with the heat transfer (HT) loss, friction loss (FL) and other internal irreversible losses. To analyze the effects of the cut-off ratio ( ) and Miller cycle ratio ( ) on the power output ( ), thermal efficiency ( ) and ecological function ( ), obtain the optimal and optimal , and compare the performance characteristics of DMC with its simplified cycles and with different optimization objective functions, the , and of irreversible DMC are analyzed and optimized by applying the finite time thermodynamic (FTT) theory. Expressions of , and are derived. The relationships among , , and compression ratio ( ) are obtained by numerical examples. The effects of and on , , , maximum power output ( ), maximum efficiency ( ) and maximum ecological function ( ) are analyzed. Performance differences among the DMC, the Otto cycle (OC), the Dual cycle (DDC), and the Otto-Miller cycle (OMC) are compared for fixed design parameters. Performance characteristics of irreversible DMC with the choice of , and as optimization objective functions are analyzed and compared. The results show that the irreversible DMC engine can reach a twice-maximum power, a twice-maximum efficiency, and a twice-maximum ecological function, respectively. Moreover, when choosing as the optimization objective, there is a 5.2% of improvement in while there is a drop of only 2.7% in compared to choosing as the optimization objective. However, there is a 5.6% of improvement in while there is a drop of only 1.3% in compared to choosing as the optimization objective.

关键词： finite-time thermodynamics     Dual-Miller cycle     power output     thermal efficiency     ecological function    

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High production of butyric acid by

Chao Ma,Jianfa Ou,Matthew Miller,Sarah McFann,Xiaoguang (Margaret) Liu

《化学科学与工程前沿（英文）》 2015年 第9卷 第3期   页码 369-375 doi: 10.1007/s11705-015-1525-3

摘要： The objective of this study was to improve the production of butyric acid by process optimization using the metabolically engineered mutant of (PAK-Em). First, the free-cell fermentation at pH 6.0 produced butyric acid with concentration of 38.44 g/L and yield of 0.42 g/g. Second, the immobilized-cell fermentations using fibrous-bed bioreactor (FBB) were run at pHs of 5.0, 5.5, 6.0, 6.5 and 7.0 to optimize fermentation process and improve the butyric acid production. It was found that the highest titer of butyric acid, 63.02 g/L, was achieved at pH 6.5. Finally, the metabolic flux balance analysis was performed to investigate the carbon rebalance in . The results show both gene manipulation and fermentation pH change redistribute carbon between biomass, acetic acid and butyric acid. This study demonstrated that high butyric acid production could be obtained by integrating metabolic engineering and fermentation process optimization.

关键词： Clostridium tyrobutyricum     butyric acid production     fermentation     mutant     pH     flux balance analysis    

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Mercury source zone identification using soil vapor sampling and analysis

David WATSON,Carrie MILLER,Brian LESTER,Kenneth LOWE,George SOUTHWORTH,Mary Anna BOGLE,Liyuan LIANG,Eric

《环境科学与工程前沿（英文）》 2015年 第9卷 第4期   页码 596-604 doi: 10.1007/s11783-014-0709-2

摘要： Development and demonstration of reliable measurement techniques that can detect and help quantify the nature and extent of elemental mercury (Hg(0)) in the subsurface are needed to reduce uncertainties in the decision-making process and increase the effectiveness of remedial actions. We conducted field tests at the Y-12 National Security Complex in Oak Ridge, Tennessee, USA, to determine if sampling and analysis of Hg(0) vapors in the shallow subsurface (<0.3 m depth) can be used to as an indicator of the location and extent of Hg(0) releases in the subsurface. We constructed a rigid polyvinyl chloride push probe assembly, which was driven into the ground. Soil gas samples were collected through a sealed inner tube of the assembly and were analyzed immediately in the field with a Lumex and/or Jerome Hg(0) analyzer. Time-series sampling showed that Hg vapor concentrations were fairly stable over time, suggesting that the vapor phase Hg(0) was not being depleted and that sampling results were not sensitive to the soil gas purge volume. Hg(0) vapor data collected at over 200 push probe locations at 3 different release sites correlated very well to areas of known Hg(0) contamination. Vertical profiling of Hg(0) vapor concentrations conducted at two locations provided information on the vertical distribution of Hg(0) contamination in the subsurface. We conclude from our studies that soil gas sampling and analysis can be conducted rapidly and inexpensively at large scales to help identify areas contaminated with Hg(0).

关键词： push probe     spill     characterization     mapping     gas    

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A comparison of production system life cycle models

Rajesh ATTRI, Sandeep GROVER

《机械工程前沿（英文）》 2012年 第7卷 第3期   页码 305-311 doi: 10.1007/s11465-012-0332-5

摘要：

Companies today need to keep up with the rapidly changing market conditions to stay competitive. The main issues in this paper are related to a company’s market and its competitors. The prediction of market behavior is helpful for a manufacturing enterprise to build efficient production systems. However, these predictions are usually not reliable. A production system is required to adapt to changing markets, but such requirement entails higher cost. Hence, analyzing different life cycle models of the production system is necessary. In this paper, different life cycle models of the production system are compared to evaluate the distinctive features and the limitations of each model. Furthermore, the difference between product life cycle and production life cycle is summarized, and the effect of product life cycle on production life cycle is explained. Finally, a production system life cycle model, along with key activities to be performed in each stage, is proposed specifically for the manufacturing sector.

关键词： production system     life cycle     model     product    

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Theory analysis and system identification methods on thermal dynamics characteristics of ballscrews

XIA Junyong, HU Youmin, WU Bo, SHI Tielin

《机械工程前沿（英文）》 2008年 第3卷 第4期   页码 408-415 doi: 10.1007/s11465-008-0061-y

摘要： Empirical model of machine tools on thermal error has been widely researched, which can compensate for thermal error to some extent but not suitable for thermal dynamic errors produced by dynamic heat sources. The thermoelastic phenomenon of unidimensional heat transfer of ballscrews influenced by changeable heat sources is analyzed based on the theory of heat transfer. Two methods for system identification (the least square system identification and BP artificial neural network (ANN) system identification) are put forward to establish a dynamic characteristic model of thermal deformation of ballscrews. The model of thermal error of the axis in a feed system of DM4600 vertical miller is established with a fine identification effect. Comparing the results of the two identification methods, the BP ANN system identification is more precise than the least square system identification.

关键词： square system     network     vertical miller     transfer     ANN    

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Analysis on carbon emission reduction intensity of fuel cell vehicles from a life-cycle perspective

《能源前沿（英文）》 doi: 10.1007/s11708-023-0909-1

摘要： The hydrogen fuel cell vehicle is rapidly developing in China for carbon reduction and neutrality. This paper evaluated the life-cycle cost and carbon emission of hydrogen energy via lots of field surveys, including hydrogen production and packing in chlor-alkali plants, transport by tube trailers, storage and refueling in hydrogen refueling stations (HRSs), and application for use in two different cities. It also conducted a comparative study for battery electric vehicles (BEVs) and internal combustion engine vehicles (ICEVs). The result indicates that hydrogen fuel cell vehicle (FCV) has the best environmental performance but the highest energy cost. However, a sufficient hydrogen supply can significantly reduce the carbon intensity and FCV energy cost of the current system. The carbon emission for FCV application has the potential to decrease by 73.1% in City A and 43.8% in City B. It only takes 11.0%–20.1% of the BEV emission and 8.2%–9.8% of the ICEV emission. The cost of FCV driving can be reduced by 39.1% in City A. Further improvement can be obtained with an economical and “greener” hydrogen production pathway.

关键词： hydrogen energy     life-cycle assessment (LCA)     fuel cell vehicle     carbon emission     energy cost    

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Improvement of the cascading closed loop cycle system

ZHANG Guoqiang, CAI Ruixian

《能源前沿（英文）》 2007年 第1卷 第3期   页码 341-346 doi: 10.1007/s11708-007-0051-5

摘要： Aspen Plus was used to simulate and get more information about the cascading closed loop cycle (CCLC) system [1–3]. Following evaluation of the variable temperature heat source (e.g. gas turbine flue gas) utilized by the CCLC, both qualitative and quantitive comparisons between the system and simple steam Rankine cycle, were made. The results indicate that CCLC has the advantage in recuperating exergy from flue gas, but it cannot sufficiently convert the recuperated exergy to useful work. To improve the utilization of low temperature flue gas heat, the properties and parameters of the working substance must match conditions of the low temperature heat source. A better cycle scheme and pressure distribution was proposed to raise the efficiency of the CCLC. In addition, the multifunction system concept was introduced to improve the performance of CCLC with solar energy.
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State-of-the-art applications of machine learning in the life cycle of solid waste management

《环境科学与工程前沿（英文）》 2023年 第17卷 第4期 doi: 10.1007/s11783-023-1644-x

摘要：

● State-of-the-art applications of machine learning (ML) in solid waste (SW) is presented.

关键词： Machine learning (ML)     Solid waste (SW)     Bibliometrics     SW management     Energy utilization     Life cycle    

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Sulfur cycle as an electron mediator between carbon and nitrate in a constructed wetland microcosm

Wenrui Guo, Yue Wen, Yi Chen, Qi Zhou

《环境科学与工程前沿（英文）》 2020年 第14卷 第4期 doi: 10.1007/s11783-020-1236-y

摘要： • Fe(III) accepted the most electrons from organics, followed by NO3‒, SO42‒, and O2. • The electrons accepted by SO42‒ could be stored in the solid AVS, FeS2-S, and S0. • The autotrophic denitrification driven by solid S had two-phase characteristics. • A conceptual model involving electron acceptance, storage, and donation was built. • S cycle transferred electrons between organics and NO3‒ with an efficiency of 15%. A constructed wetland microcosm was employed to investigate the sulfur cycle-mediated electron transfer between carbon and nitrate. Sulfate accepted electrons from organics at the average rate of 0.84 mol/(m3·d) through sulfate reduction, which accounted for 20.0% of the electron input rate. The remainder of the electrons derived from organics were accepted by dissolved oxygen (2.6%), nitrate (26.8%), and iron(III) (39.9%). The sulfide produced from sulfate reduction was transformed into acid-volatile sulfide, pyrite, and elemental sulfur, which were deposited in the substratum, storing electrons in the microcosm at the average rate of 0.52 mol/(m3·d). In the presence of nitrate, the acid-volatile and elemental sulfur were oxidized to sulfate, donating electrons at the average rate of 0.14 mol/(m3·d) and driving autotrophic denitrification at the average rate of 0.30 g N/(m3·d). The overall electron transfer efficiency of the sulfur cycle for autotrophic denitrification was 15.3%. A mass balance assessment indicated that approximately 50% of the input sulfur was discharged from the microcosm, and the remainder was removed through deposition (49%) and plant uptake (1%). Dominant sulfate-reducing (i.e., Desulfovirga, Desulforhopalus, Desulfatitalea, and Desulfatirhabdium) and sulfur-oxidizing bacteria (i.e., Thiohalobacter, Thiobacillus, Sulfuritalea, and Sulfurisoma), which jointly fulfilled a sustainable sulfur cycle, were identified. These results improved understanding of electron transfers among carbon, nitrogen, and sulfur cycles in constructed wetlands, and are of engineering significance.

关键词： Constructed wetland     Sulfur cycle     Electron transfer     Denitrification    

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Life-cycle cost analysis of optimal timing of pavement preservation

Zilong WANG,Hao WANG

《结构与土木工程前沿（英文）》 2017年 第11卷 第1期   页码 17-26 doi: 10.1007/s11709-016-0369-3

摘要： Optimal application of pavement preservation or preventive maintenance is critical for highway agencies to allocate the limited budget for different treatments. This study developed an integrated life-cycle cost analysis (LCCA) model to quantify the impact of pavement preservation on agency cost and vehicle operation cost (VOC) and analyzed the optimal timing of preservation treatments. The international roughness index (IRI) data were extracted from the long-term pavement performance (LTPP) program specific pavement studies 3 (SPS-3) to determine the long-term effectiveness of preservation treatments on IRI deterioration. The traffic loading and the initial IRI value significantly affects life extension and the benefit of agency cost caused by pavement preservation. The benefit in VOC is one to two orders greater in magnitude as compared to the benefit in agency cost. The optimal timing calculated based on VOC is always earlier than the optimal timing calculated based on agency cost. There are considerable differences among the optimal timing of three preservation treatments.

关键词： pavement preservation     life-cycle cost analysis     agency cost     vehicle operation cost    

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Performance analysis of cogeneration systems based on micro gas turbine (MGT), organic Rankine cycleand 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)    

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Co-hydrotreating light cycle oil-canola oil blends

Huali WANG, Hena FAROOQI, Jinwen CHEN

《化学科学与工程前沿（英文）》 2015年 第9卷 第1期   页码 64-76 doi: 10.1007/s11705-015-1504-8

摘要： Canola oil and light cycle oil (LCO) blends were co-hydrotreated over a commercial hydrotreating catalyst (NiMo/Al O ) to produce diesel fuel with a green diesel component. High hydrodeoxygenation, hydrodesulphurization and hydrodenitrogenation catalytic activities were achieved for all three feedstocks tested in the temperature range of 350–380 °C with a hydrogen pressure of 7 MPa and a gas/oil ratio of 800 nL/L. The hydrocracking conversion of the 360 °C+ materials in the feedstocks increased by 5% and 15% when 5 and 7.5 wt-% canola oil was added to the LCO, respectively. Compared to the pure LCO, the cetane index of the diesel product formed from hydrotreating the two canola oil-LCO blends increased by 2.5 and 4, respectively. Due to the higher hydrogen requirement to crack and deoxygenate the triglycerides contained in the canola oil, a higher hydrogen consumption was needed to hydrotreat the canola oil-LCO blends.

关键词： hydrotreating     co-hydrotreating     co-processing     canola oil     light cycle oil (LCO)    

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Life cycle cost savings analysis on traditional drainage systems from low impact development strategies

Pengfei ZHANG, Samuel T. ARIARATNAM

《工程管理前沿（英文）》 2021年 第8卷 第1期   页码 88-97 doi: 10.1007/s42524-020-0063-y

摘要： Areas that are covered with natural vegetation have been converted into asphalt, concrete, or roofed structures and have increased surface impermeability and decreased natural drainage capability. Conventional drainage systems were built to mimic natural drainage patterns to prevent the occurrence of waterlogging in developed sites. These drainage systems consist of two major components: 1) a stormwater conduit system, and 2) a runoff storage system. Runoff storage systems contain retention basins and drywells that are used to store and percolate runoff, whereas conduit systems are combination of catch basins and conduit pipes used to collect and transport runoff. The construction of these drainage systems is costly and may cause significant environmental disturbance. In this study, low impact development (LID) methods that consist of extensive green roofs (GRs) and permeable interlocking concrete pavements (PICPs) are applied in real-world construction projects. Construction project documents were reviewed, and related cost information was gathered through the accepted bidding proposals and interviews of specialty contractors in the metropolitan area of Phoenix, Arizona. Results indicate that the application of both LID methods to existing projects can save an average of 27.2% in life cycle costs (LCC) for a 50-year service life and 18.7% in LCC for a 25-year service life on the proposed drainage system, respectively.

关键词： low impact development     traditional drainage system     hydraulic benefits     life-cycle cost    

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标题 作者 时间 类型 操作

Effect of variable heat capacities on performance of an irreversible Miller heat engine

Xingmei YE

期刊论文

Improvement of engine performance with high compression ratio based on knock suppression using Millercycle with boost pressure and split injection

Haiqiao WEI, Jie YU, Lei ZHOU

期刊论文

Optimization of the power, efficiency and ecological function for an air-standard irreversible Dual-Millercycle

Zhixiang WU, Lingen CHEN, Yanlin GE, Fengrui SUN

期刊论文

High production of butyric acid by

Chao Ma,Jianfa Ou,Matthew Miller,Sarah McFann,Xiaoguang (Margaret) Liu

期刊论文

Mercury source zone identification using soil vapor sampling and analysis

David WATSON,Carrie MILLER,Brian LESTER,Kenneth LOWE,George SOUTHWORTH,Mary Anna BOGLE,Liyuan LIANG,Eric

期刊论文

A comparison of production system life cycle models

Rajesh ATTRI, Sandeep GROVER

期刊论文

Theory analysis and system identification methods on thermal dynamics characteristics of ballscrews

XIA Junyong, HU Youmin, WU Bo, SHI Tielin

期刊论文

Analysis on carbon emission reduction intensity of fuel cell vehicles from a life-cycle perspective

期刊论文

Improvement of the cascading closed loop cycle system

ZHANG Guoqiang, CAI Ruixian

期刊论文

State-of-the-art applications of machine learning in the life cycle of solid waste management

期刊论文

Sulfur cycle as an electron mediator between carbon and nitrate in a constructed wetland microcosm

Wenrui Guo, Yue Wen, Yi Chen, Qi Zhou

期刊论文

Life-cycle cost analysis of optimal timing of pavement preservation

Zilong WANG,Hao WANG

期刊论文

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

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

期刊论文

Co-hydrotreating light cycle oil-canola oil blends

Huali WANG, Hena FAROOQI, Jinwen CHEN

期刊论文

Life cycle cost savings analysis on traditional drainage systems from low impact development strategies

Pengfei ZHANG, Samuel T. ARIARATNAM

期刊论文