检索结果-南通市图书馆

Experimental investigation into the oxidation reactivity,morphology and graphitization of soot particles from diesel/n-octanol mixtures

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2022年第2期34卷 218-230页

作者： Qiongyang Zhou Ying Wang Xiaochen Wang Yuanqi Bai School of Energy and Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Aiming to investigate the impacts of n-octanol addition on the oxidation reactivity,morphology and graphitization of diesel exhaust particles,soot samples were collected from a four-cylinder turbocharged diesel engine fueled with D100(neat diesel fuel),DO15(85%diesel and 15%n-octanol,V/V)and DO30(70%diesel and 30%n-octanol,V/V).All tests were conducted at two engine speeds of 1370 and 2150 r/min under a fixed torque of 125 N·m.The soot properties were characterized by thermogravimetric analyzer(TGA),transmission electron microscopy(TEM)and Raman spectroscopy(RS).The higher volatile organic fraction content,lower soot oxidation temperatures and lower activation energy from TGA results indicated that both the increasing n-octanol concentration and engine speed enhanced the soot oxidation reactivity.Additionally,quantitative analysis of TEM images showed that the soot derived from DO30 had the smallest primary particle diameters and fractal dimension,followed by those of soot produced by DO15 and D100.The RS results demonstrated that the n-octanol addition and higher engine speed led to a larger D1-FWHM(D1-full width at half maximum),A_(D1)/A_(T)(area ratio of D1 band and the total spectral)and A_(D3)/A_(T)(area ratio of D3 band and the total spectral)as well as a smaller L_(a)(crystallite width),revealing a lower degree of graphitization.Furthermore,the correlations between characterization parameters of soot properties and reactivity were nonlinear.

关键词： Oxidation reactivity Morphology Graphitization Diesel exhaust particles n-Octanol

槽道湍流中动量和被动标量输运特性及其相关性研究

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2022年第10期38卷 92-106页

作者：田阿慧刘锋周毅 School of Energy and Power Engineering Nanjing University of Science and TechnologyNanjing210094China School of Energy and Power Engineering North University of ChinaTaiyuan030051China

对雷诺数Re_(τ)=u_(τ)δ/ν=180(u_(τ)为摩擦速度,δ为槽道半宽,ν为运动黏度)及普朗特数Pr=0.71的槽道湍流开展直接数值以研究槽道湍流中动量和被动标量的输运特性及两者间的相关性.研究结果表明单点能量和标量输运之间存在明显的... 详细信息

对雷诺数Re_(τ)=u_(τ)δ/ν=180(u_(τ)为摩擦速度,δ为槽道半宽,ν为运动黏度)及普朗特数Pr=0.71的槽道湍流开展直接数值以研究槽道湍流中动量和被动标量的输运特性及两者间的相关性.研究结果表明单点能量和标量输运之间存在明显的正相关性,并且生产项之间的相关性总是大于其他项之间的相关性.通过计算Karman-Howarth-Monin-Hill方程和尺度间标量输运方程,研究了法向方向两个距离壁面不同位置处两点间能量和标量输运特性(靠近壁面的位置y^(+)=10,另一个远离壁面的位置y^(+)=60).在y^(+)=10处,在展向方向观察到由动量条带及标量条带拉伸引起的能量和标量的反向传递现象,而在流向和垂直方向观察到尺度间正向能量和标量传递现象.两点间能量输运的物理机制(例如,能量产生、耗散和黏性扩散)与两点间标量输运的物理机制非常相似.能量及标量输运机制的相关性与动量条带和标量条带之间的相似性密不可分.This is a preview of subscription content,access via your institution.

关键词：传递现象输运特性 Hill方程摩擦速度普朗特数能量产生运动黏度能量输运

Visualization on electrified micro-jet instability from Taylor cone in electrohydrodynamic atomization

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical engineering 2022年第4期35卷 456-465页

作者： Shiqi Yang Zhentao Wang Qian Kong Bin Li Junfeng Wang School of Energy and Power Engineering Jiangsu UniversityZhenjiang 212013China

The cone-jet in electrohydrodynamic atomization has been widely applied into numerous industrial fields owing to micro-sized drops with narrow distribution and high charge.The electrified jet emits from a single capillary sheathed with quartz tube is visualized versus operating parameters and physical properties,and breakup instabilities are also discussed.The range of operating parameters for a steady conejet broadens,as well as the minimum flow rate.Taylor cone angle decreases with an increase in flow rate,while increases as electric potential increasing.The jet breakup length decreases with an increase in flow rate and conductivity,while increases as electric potential increasing.The diffusion angle increases as flow rate increasing,while decrease as electric potential and conductivity increasing.Much clearer whipping instabilities are observed with an increase in“electro-Weber”number and conductivity.The completion in disturbance or/and suppression from axial and radial stresses,drag force dominates the variation.Meanwhile,for a large flow rate,the transition from varicose instabilities to whipping instabilities is found.The whipping instabilities are clearly observed for high conductivity due to much more free ions in liquid.For much higher conductivity,an intermittent electrified jet appears and shows an umbrella plume,and breakup length sharply shortens.

关键词： EHDA Cone-jet regime Electrified jet Conductivity instability

Conductivity and tribological properties of IL-PANI/WS_(2) composite material in lithium complex grease

在线全文

学校读者我要写书评

暂无评论

Friction 2023年第6期11卷 977-991页

作者： Yanqiu XIA Yuanhui WANG Chenglong HU Xin FENG school of energy power and Mechanical engineering North China Electric Power UniversityBeijing102206China

An ionic liquid-polyaniline/tungsten disulfide(IL-PANI/WS_(2))composite was synthesized in 1-butyl-3-methylimidazole tetrafluoroborate(LB104)aqueous solution by in-situ polymerization and characterized by Fourier transform infrared spectroscopy.A current-carrying friction and wear tester was used to study the tribological properties of steel-steel and copper-copper friction pairs lubricated by an IL-PANI/WS_(2) lithium complex grease(LCG).After the experiment,scanning electron microscope was used to observe the surface morphology of the wear scar on the steel and copper plates,and X-ray photoelectron spectrometer was used to analyze the elemental composition of the wear scar surface.The results show that compared with greases containing IL-PANI and WS_(2),greases containing IL-PANI/WS_(2) exhibit better antiwear performance when lubricating steel-steel friction pairs and better tribological performance and electrical conductivity when lubricating copper-copper friction pairs.Therefore,it can be concluded that WS_(2) and IL-PANI have a synergistic effect.

关键词： lithium complex grease(LCG) current-carrying friction additive ionic liquid-polyaniline/tungsten disulfide(IL-PANI/WS_(2))

energy-Saving Optimization Study on 700°C Double Reheat Advanced Ultra-Supercritical Coal-Fired power Generation System

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2023年第1期32卷 30-43页

作者： WANG Jing DUAN Liqiang YANG Jinfu YANG Ming JING Yutian TIAN Liguo school of energy power and Mechanical engineering North China Electric Power University Institute of engineering Thermophysics Chinese Academy of Sciences

700°C double reheat advanced ultra-supercritical power generation technology is one of the most important development directions for the efficient and clean utilization of coal. To solve the great exergy loss problem caused by the high superheat degrees of regenerative steam extractions in 700°C double reheat advanced ultra-supercritical power generation system, two optimization systems are proposed in this paper. System 1 is integrated with the back pressure extraction steam turbine, and system 2 is simultaneously integrated with both the outside steam cooler and back pressure extraction steam turbine. The system performance models are built by the Ebsilon Professional software. The performances of optimized systems are analyzed by the unit consumption method. The off-design performances of optimization systems are analyzed. The results show that: the standard power generation coal consumption rates of optimization systems 1 and 2 are decreased by 1.88 g·(kW·h)–1, 2.97 g·(kW ·h)–1compared with that of the 700°C reference system; the average superheat degrees of regenerative steam extractions of optimized systems 1 and 2 are decreased by 122.2°C, 140.7°C(100% turbine heat acceptance condition), respectively. The comparison results also show that the performance of the optimized system 2 is better than those of the optimized system 1 and the 700°C reference system. The power generation standard coal consumption rate and the power generation efficiency of the optimized system 2 are about 232.08 g·(kW ·h)–1and 52.96%(100% turbine heat acceptance condition), respectively.

关键词： 700 °C advanced ultra-supercritical (A-USC) double reheat cycle extraction steam superheat degree unit consumption method system optimization

Comparison of Thermal Performance between Annular Fins and Longitudinal Fins in Latent Heat Storage Unit

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2023年第3期32卷 1227-1238页

作者： ZHU Yuxi QIU Yan School of Energy and Power Engineering Shandong UniversityJi'nan 250061China

As a simple and effective method of heat transfer enhancement,fins are widely used in latent heat storage systems.However,the choice of annular fins and longitudinal fins has always been controversial.In this paper,the melting process of phase change material(PCM)in annular fins and longitudinal fins latent heat storage units with the same volume is numerically simulated.To ensure the same thermal penetration,three-dimensional spaces occupied with fins are specially controlled to be the same.Combined with finned structures,the effects of natural convection(NC),placement mode and heat transfer fluid(HTF)inlet direction on the melting process are studied.The results show that the melting time in annular finned structure is always 10%less than that in longitudinal finned structure,which demonstrates the superior of the annular fins in the latent heat storage unit.The melting time is the shortest in vertical unit with annular fins and HTF inlet at the bottom.Additionally,the correlation formulas of the liquid fraction are proposed in the vertical unit with HTF inlet at the bottom.

关键词： latent heat storage annular fins longitudinal fins natural convection

Performance-Driven Multi-Objective Optimization Method for DLR Transonic Tandem Cascade Shape Design

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2023年第1期32卷 297-309页

作者： LI Kunhang MENG Fanjie WANG Kaibin GUO Penghua LI Jingyin School of Energy and Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Transonic tandem cascades can effectively increase the working load,and this feature conforms with the requirement of the large loads and pressure ratios of modern axial compressors.This paper presents an optimization strategy for a German Aerospace Center(DLR)transonic tandem cascade,with one front blade and two rear blades,at the inlet Mach number of 1.051.The tandem cascade profile was parameterized using 19 control parameters.Non-dominated sorting Genetic algorithm(NSGA-II)was used to drive the optimization evolution,with the computational fluid dynamics(CFD)-based cascade performances correction added for each generation.Inside the automatic optimization system,a pressure boundary condition iterative algorithm was developed for simulating the cascade performance with a constant supersonic inlet Mach number.The optimization results of the cascade showed that the deflection of the subsonic blade changed evidently.The shock wave intensity of the first blade row was weakened because of the reduced curvatures of the optimized pressure and suction sides of the front blade part and the downstream moved maximum thickness position.The total pressure losses decreased by 15.6%,20.9%and 19.9%with a corresponding increase in cascade static pressure ratio by 1.3%,1.8%and 1.7%,for the three cascade shapes in the Pareto solution sets under the near choke,the design and near stall conditions,respectively.

关键词： transonic tandem cascade cascade parameterization strategy aerodynamic design performance-driven multi-objective optimization methodology

CFD-Based Optimization of a Diesel Engine Waste Heat Recycle System

在线全文

学校读者我要写书评

暂无评论

Fluid Dynamics & Materials Processing 2023年第6期19卷 1479-1493页

作者： Da Li Guodong Zhang Ke Sun Shuzhan Bai Guoxiang Li School of Energy and Power Engineering Shandong UniversityJinan250061China

A dedicated heat exchanger model is introduced for the optimization of heavy-duty diesel engines.The model is a prerequisite for the execution of CFD simulations,which are used to improve waste heat recovery in these systems.Several optimization methods coupled with different types of working fluids are compared in terms of exergy efficiency and heat exchanger complicity.The three considered optimization methods all lead to significant improvements in the R245fa and R1233zd systems with a comparatively low evaporation temperature.The optimal R245fa system has the highest efficiency increase(77.49%).The cyclopentane system displays the highest efficiency among the optimized ORC(Organic Rankine Cycle)systems,yet achieved by using a much heavier evaporator HEC(Heat Exchanging Core).In contrast,the 96.84%efficiency increase for the optimized R1233zd is achieved with only 68.96%evaporator weight.

关键词： Tube-fin heat exchanger heat exchanging core organic rankine cycle working fluid

A review on 3d transition metal dilute magnetic REIn_(3) intermetallic compounds

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2022年第3期31卷 76-83页

作者：郭新鹏郭永权殷林瀚何强 school of energy power and Mechanical engineering North China Electric Power UniversityBeijing 102206China

The dilute magnetic intermetallic compound(DMIC) is an extended study of the dilute magnetic semiconductor. The giant magnetic effect and room temperature ferromagnetism are induced by doping minor 3d transition metal into REIn_(3) intermetallic compound. Owing to the metallic processability, the REIn_(3)-based DMIC might have the potential application as magnetoelectric device. In this review, the structural stability, magnetic and electric transport properties of REIn_(3-x)T_(x)(RE = rare earth;T = Co, Mn, Fe;x = 0–0.3) have been systematically summarized and analyzed.

关键词： dilute magnetic intermetallic compounds phase transition magnetic properties magnetic transport