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In situ regulating intimately connected heterostructure by decomposition of solid solution oxides toward high-efficient water oxidation

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Rare Metals 2024年第4期43卷 1557-1569页

作者： Shao-Fei Zhang Xiao-Lu Yin Jin Wang Jian-Li Kang Tian-Tian Li Jin-Feng Sun Yong-Qiang Meng Jian-Jiang Wang Dian-Long Wang Kai-Qiang Qin Hebei Key Laboratory of Flexible Functional Materials/Hebei Key Laboratory of Material Near-Net Forming Technology School of Materials Science and EngineeringHebei University of Science and TechnologyShijiazhuang050018China Key Laboratory of Advanced Ceramics and Machining Technology/Ministry of Education School of Materials Science and EngineeringTianjin UniversityTianjin300072China Electrochemical engine Center Department of Mechanical EngineeringPennsylvania State UniversityUniversity ParkPA16802USA

Heterogeneous interfaces produced by interdomain interactions on a nanoscale performs a crucial role in boosting the properties of an electrocatalyst toward oxygen evolution reaction(OER)***,a series of dual-phase electrodes with intimately connected heterointerfaces are prepared by in situ decomposing solid solution oxide of Ni_(x)Co_(y)Fe_(100-x-y)O,which grew on Ni foam massively via an ultrafast combustion ***,with high-reaction kinetics caused by the reduction treatment at 450℃,the less electronegative Fe and Co are more oxyphilic than Ni,which facilitated their co-exsolution and formation of CoFe_2O_4/NiO oxide with enriched oxygen *** from the nanoporous framework,heterojunction structure,and oxygen defects,the self-supporting electrodes present rapid charge/mass transmission and provide abundant active sites for *** optimized sample(R-SNCF4.5)shows low overpotentials of 226 and 324 mV at 10 and100 mA·cm^(-2),a small Tafel slope(46.7 mV·dec^(-1)),and excellent *** assembled R-SNCF4.5//Pt/C/NF electrolyzer demonstrates continuous electrolysis over 50 h at a current density of 10 mA·cm^(-2),under 1.51 *** functional theory(DFT)calculations verify that the strong electronic modulation plays a critical part in the CoFe_2O_4/NiO hybrid by lowering the energy barriers for the ratedetermining steps,and Fe sites are the most active OER sites.

关键词： Rapid combustion Decomposition of solid solution oxide Dual-phase heterostructure Oxygen evolution reaction Theoretical calculation

Emission Performance of Motorcycles in Real-Road Conditions

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Transactions of Tianjin University 2007年第5期13卷 322-327页

作者：杜青刘欣尹君尹涛赵杰郭津 internal combustion engine Research Institute Tianjin University

WMTC,which means a worldwide motorcycle testing cycle,is now regarded as the most possible choice for the global motorcycle emission testing cycle,but whether or not it can be used in China is still *** this study,a large number of data on the speed-time trace of motorcycles were sampled from various kinds of roads in 5 cities in *** on a series of criterion numbers defined,the driving character of motorcycles in the real-road conditions of China was *** the aid of a specially designed program,an emission testing cycle that can indicate the driving characteristics of motorcycle in the real-road conditions was synthesized,and the exhaust emission tests of 20 motorcycles under the synchronized cycle and WMTC were carried out based on a CVS system and a motorcycle chassis *** results show that although there do exist differences in some criterion numbers between the real-road condition and WMTC,such as proportion of idling mode,mean speed,mean running speed and the average acceleration and deceleration rates,the driving behaviors are *** results of exhaust emission tests indicate that the emission values of motorcycles under the synchronized cycle and WMTC have a relatively strong *** means that WMTC can be introduced as a standard motorcycle emission test regulation into China.

关键词：发射性能摩托车驾驶性能实验周期

Study the ethanol SI/HCCI combustion mode transition by using the fast thermal management system

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Chinese Science Bulletin 2007年第19期52卷 2731-2736页

作者： PENG YaPing TAN ManZhi GUO Liang LIU FaFa LI Hua GUO YingNan department of internal combustion engine Campus Nanling Jilin University Changchun 130022 China

In this paper the ethanol homogeneous charge compression ignition (HCCI) is achieved in a modified single cylinder engine by means of a self-developed fast thermal management system (FTMS), and the ethanol SI/HCCI operation regions are defined. It can be concluded that the thermal efficiency is higher and the NOx emission is lower in the HCCI operation region. In addition, the maximum NOx emission drops by 98%. The ethanol SI/HCCI combustion mode transition is conducted in different conditions near the SI/HCCI operation boundaries. It is likely to realize the transition by the utilization of FTMS. However, it is impossible to complete the transition within one operating cycle under current operation conditions. There are fluctuations in engine speed and brake mean effective pressure during the transition process. In order to reduce the fluctuations during the transition, the initial work concerning the effects of the spark ignition on the transition smoothness is carried out and the investigation indicates that the engine speed and brake mean effective pressure fluctuations cannot be eradicated only through spark ignition. Therefore, the control strategies combined with other factors should be further optimized.

关键词：电荷压缩点火乙醇燃烧模型火花

Explore artificial neural networks for solving complex hydrocarbon chemistry in turbulent reactive flows

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Fundamental Research 2022年第4期2卷 595-603页

作者： Jian An Fei Qin Jian Zhang Zhuyin Ren Institte for Aero engine Tsinghua UniversitBejing 100084China Seience and Technology on combustion Internal Flow and Thermal-structure LaboratoryNorthwesterm Polytechnical UniversityXi'an 710072China

Global warming caused by the use of fossil fuels is a common concern of the world *** is of practical importance to conduct in-depth fundamental research and optimal design for modern engine combustors through However,complex hydrocarbon chemistry,an indispensable component for predictive modeling,is computahigh-fidelity computational fluid dynamics(CFD),so as to achieve energy conservation and emission *** demanding,Its application in simulation-based design optimization,although desirable,is quite *** address this challenge,we propose a methodology for representing complex chemistry with artificial neural networks(ANNs),which are trained with a comprehensive sample dataset generated by the Latin hypercube sampling(LHS)*** a given chemical kinetic mechanism,the thermochemical sample data is able to cover the whole accessible pressure/temperature/species space in various turbulent *** ANN-based model consists of two different layers:the self-organizing map(SOM)and the back-propagation neural network(BPNN).The methodology is demonstrated to represent a 30-species methane chemical *** obtained ANN model is applied to simulate both a non-premixed turbulent flame(DLR_A)and a partially premixed turbulent flame(Flame D)to validate its applicability for different *** show that the ANN-based chemical kinetics can reduce the computational cost by about two orders of magnitude without loss of accuracy,The proposed methodology can successfully construct an ANN-based chemical mechanism with significant ffciency gain and a broad scope of applicability,and thus holds a great potential for complex hydrocarbon fuels.

关键词： Chemical kinetics Turbulent combustion Artificial neural network Machine learning Numerical simulation

Characteristics of the Main Journal Bearings of an engine Based on Non-linear Dynamics

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Chinese Journal of Mechanical engineering 2009年第5期22卷 755-759页

作者： NI Guangjian ZHANG Junhong CHENG Xiaoming State Key Laboratory of engine Tianjin University Tianjin 300072 China Tianjin internal combustion engine Research Institute Tianjin 300072 China

Many simple nonlinear main journal bearing models have been studied theoretically, but the connection to existing engineering system has not been equally investigated. The consideration of the characteristics of engine main journal bearings may provide a prediction of the bearing load and lubrication. Due to the strong non-linear features in bearing lubrication procedure, it is difficult to predict those characteristics. A non-linear dynamic model is described for analyzing the characteristics of engine main journal bearings. Components such as crankshaft, main journals and con rods are found by applying the finite element method. Non-linear spring/dampers are introduced to imitate the constraint and supporting functions provided by the main bearing and oil film. The engine gas pressure is imposed as excitation on the model via the engine piston, con rod, etc. The bearing reaction force is calculated over one engine cycle, and meanwhile, the oil film thickness and pressure distribution are obtained based on Reynolds differential equation. It can be found that the maximum bearing reaction force always occurs when the maximum cylinder pressure arises in the cylinder adjacent to that bearing. The simulated minimum oil film thickness, which is 3 μm, demonstrates the reliability of the main journal bearings. This non-linear dynamic analysis may save computing efforts of engine main bearing design and also is of good precision and close connection to actual engine main journal bearing conditions.

关键词： non-linear dynamics engine main journal bearings

Piston-ring and Cylinder-liner Lubrication in internal combustion engines Based on Thermo-hydrodynamic

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Chinese Journal of Mechanical engineering 2011年第6期24卷 971-975页

作者： ZHANG Junhong GAO Hongge NI Guangjian State Key Laboratory of engine Tianjin UniversityTianjin 300072China Tianjin internal combustion engine Research Institute Tianjin 300072China

Currently the extruded effect,roughness to the lubricant shear thinning,temperature changes and other factors or some combination of a single factor mainly considered in the lubrication study of piston *** the study of the energy equation,the oil viscosity-temperature properties,adsorption layer characteristics are usually not *** the theoretical research is different from the actual situation of *** lubrication of piston ring-cylinder liner system in internal combustion(IC) engines is studied here based on the theory of thermal *** unsteady and compressible hydrodynamic lubrication model with an equivalent viscosity based on shear and extruded flow factor is derived by employing the viscosity-temperature relationship,meanwhile,characteristics such as lubricating oil’s density varying with pressure and temperature,thickness of adsorbent layer and oil film’s geometry are also considered in this *** setting up the energy equation,the effect of lubricating oil’s volume expansion and viscous dissipation on temperature,the heat conduction along oil film’s thickness direction are *** difference equation is formed by using a first-order difference scheme in time scale and second-order difference scheme in space scale.A common diesel engine is introduced as an instance to predict the distribution of the minimum oil film thickness in the piston ring-cylinder liner *** results of simulation calculation show that the minimum oil film thickness will decrease especially around the top dead center when the oil’s volume expansion,viscous dissipation and heat conduction are considered,which implies that:it is essential to take the thermal flow idea into account during investigating piston ring-cylinder liner system’s lubrication.A more complete piston ring-cylinder liner lubrication theory was established according to thermal fluids from the perspective of *** is more helpful to guide the practical applicat

关键词： thermal flow piston ring-cylinder liner adsorbent layer viscosity-temperature revision

Experimental Investigation of the Influence of Fuel Viscosity on the Spray Characteristics of Diesel Nozzle

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Journal of Shanghai Jiaotong university(Science) 2007年第1期12卷 61-65页

作者：吕兴才乔信起陈剑黄震 Inst.of internal combustion engine Shanghai Jiaotong Univ.

This paper presented an investigation of atomization characteristics including the velocity vector field and the mean droplet sizes for different percentages of DMM-diesel blended fuels using a phase doppler anemometry (PDA) analyzer system. Based on the fuel design concept, an oxygenated fuel named dimethoxy methane (DMM), which has lower viscosity, surface tension, and boiling point, was used to blend with diesel. The experiments were carried out under atmospheric conditions on a single-hole type diesel nozzle, liquid conditions comprise a temperature of 298 K under the needle valve opening pressure of 6 MPa. The results show that the sauter mean diameter (SMD) and spray cone angle of blended fuels decrease with the increase of DMM content; the axial mean velocity in the centerline increases with the increase of DMM. However, the spray behavior of blended fuel in which DMM exceeds 75% is virtually identical to that of neat DMM. The measurement also reveals the existence of an "S" shape in the radial mean velocity variations with radial distance.

关键词：喷雾性状多普勒相位测试法燃料设计概念动力粘质

Fuel design real-time to control HCCI combustion

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Chinese Science Bulletin 2006年第21期51卷 2673-2680页

作者： HOU Yuchun HUANG Zhen LU Xingcai FANG Junhuan ZU Linlin Institute of internal combustion engine Shanghai Jiao Tong UniversityShanghai 200030 China

In order to achieve lower emissions and extensive load in the homogeneous charge com- pression ignition (HCCI) engine system, a novel fuel design concept that high-octane number fuel and high-cetane number fuel are mixed real-time to con- trol HCCI combustion is proposed in this study. HCCI combustion fueled with iso-octane/n-heptane mix- tures controlled real-time on a single-cylinder HCCI combustion engine is studied. The test results show that the equivalence ratio of n-heptane in mixtures decides ignition and controls the combustion phase of HCCI combustion. The addition of iso-octane ex- tends knocking limit in equivalence ratio somewhat, but knocking occurrence mainly depends on the total concentration of mixture. Although operating range in equivalence ratio becomes narrow with the increas- ing proportion of iso-octane, the maximum load of HCCI combustion fueled with iso-octane/n-heptane mixtures controlled real-time is increased about 80% more than that of pure n-heptane. When iso-octane/ n-heptane mixtures are controlled in optimized method, it is proved that the load of HCCI combustion can be fully extended and emissions can be de- creased remarkably, while at the same time the higher indicated thermal efficiencies are obtained over the extensive operation range.

关键词： HCCI 燃料设计实时控制正庚烷异辛烷

Degradation prediction of proton exchange membrane fuel cell stack using semi-empirical and data-driven methods

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能源与人工智能(英文) 2023年第1期11卷 1-11页

作者： Yupeng Wang Kangcheng Wu Honghui Zhao Jincheng Li Xia Sheng Yan Yin Qing Du Bingfeng Zu Linghai Han Kui Jiao State Key Laboratory of engines Tianjin University135 Yaguan RoadTianjin300350China Powertrain department General R&D InstituteFAWNo.1 Xinhongqi StreetChangchunJilin 130013China internal combustion engine Research Institute Tianjin University92 Weijin RoadTianjin300072China

Degradation prediction of proton exchange membrane fuel cell(PEMFC)stack is of great significance for improving the rest useful *** this study,a PEMFC system including a stack of 300 cells and subsystems has been tested under semi-steady operations for about 931 ***,two different models are respectively established based on semi-empirical method and data-driven method to investigate the degradation of stack *** is found that the root mean square error(RMSE)of the semi-empirical model in predicting the stack voltage is around 1.0 V,while the predicted voltage has no local dynamic characteristics,which can only reflect the overall degradation trend of stack *** RMSE of short-term voltage degradation predicted by the DDM can be less than 1.0 V,and the predicted voltage has accurate local variation ***,for the long-term prediction,the error will accumulate with the iterations and the deviation of the predicted voltage begins to fluctuate gradually,and the RMSE for the long-term predictions can increase to 1.63 *** on the above characteristics of the two models,a hybrid prediction model is further *** prediction results of the semi-empirical model are used to modify the input of the data-driven model,which can effectively improve the oscillation of prediction results of the data-driven model during the long-term *** is found that the hybrid model has good error distribution(RSEM=0.8144 V,R2=0.8258)and local performance dynamic characteristics which can be used to predict the process of long-term stack performance degradation.

关键词： Proton exchange membrane fuel cell system Data-driven method Semi-empirical equation Degradation experiments