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Experimental study on premixed combustion of spherically propagating methanol-air-nitrogen flames

中国高等学校学术文摘·能源与动力工程 2010年第2期4卷 223-233页

作者： Xiangang WANG Zhiyuan ZHANG Zuobua HUANG Xibin WANG Haiyan MIAO State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

The outward propagation and development of surface instability of the spark-ignited spherical premixed flames for methanol-air-nitrogen mixtures were experimentally studied by using a constant volume combustion chamber and a high-speed schlieren photography system. The laminar burning velocities, the mass burning fluxes, and the Markstein lengths were obtained at different equivalence ratios, dilution ratios, initial temperatures, and pressures. The laminar burning velocities and the mass burning fluxes give a similar curve versus the equivalence ratios. They increase with the increase of initial temperature and decrease with the increase of dilution ratio. The laminar burning velocity decreases with elevating the initial pressure, while the mass burning flux increases with the increase of the initial pressure. Markstein length decreases slightly with the increase of initial temperature for the rich mixtures. High initial pressure corresponds to low Markstein length. Markstein length increases with the increase of dilution ratio, which is more obvious when the mixture becomes leaner. Equivalence ratio has a slight impact on the development of the diffusive-thermal cellular structure at elevated initial pressures. The initial pressure has a significant influence on the occurrence of the flame front cellular structure. At the elevated pressures, the cracks on the flame surface branch and develop into the cell structure. These cells are bounded by cracks emitting a bright light, which may indicate soot formation. For very lean mixture combustion, the buoyancy effect and cooling effect from the spark electrodes have a significant impact on the flame propagation. The hydrodynamic instability, inhibited with the increase of initial temperature around the stoichiometric equivalence ratio, is enhanced with the increase of initial pressure and suppressed by mixture dilution.

关键词： methanol spherical flame propagation characteristics flame instabilities

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Experimental research on catalysts and their catalytic mechanism for hydrogen production by gasification of peanut shell in supercritical water

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中国高等学校学术文摘·能源与动力工程 2007年第4期1卷 451-456页

作者： PEI Aixia GUO Liejin JIN Hui State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Peanut shell,mixed with sodium carboxymethylcellulose,was gasified at a temperature of 450℃ and a pressure range from 24 to 27 MPa with the presence of different catalysts,including K2CO3,ZnCl2 and *** experimental results show that different catalysts have greatly different effects on the *** efficiency (GE),hydrogen gasification efficiency (GHE),carbon gasification efficiency (GCE),yield of hydrogen production (YH2) and potential yield of hydrogen production (YPH2) are applied to describe the catalytic *** the result of gaseous components,ZnCl2 has the highest hydrogen selectivity,K2CO3 is lower,and Raney-Ni is the lowest,but Raney-Ni is the most favorable to gasify biomass among the three catalysts,and its GE,GHE,GcE reach 126.84%,185.71%,94.24%,*** expected,hydrogen selectivity increased and CH4 reduced rapidly when the mixture of ZnCl2 and Raney-Ni is used under the same *** optimization mixture appeared when 0.2 g of ZnCl2 was added to 1 g of Raney-Ni,43.56 g·kg-1 of hydrogen production was *** addition,the catalytic mechanisms of different catalysts were analyzed,and the possible reaction pathway was brought forward,which helped to explain the experiment phenomena and results correctly.

关键词： biomass supercritical water gasification,hydrogen production

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Influence of cetane number improver on performance and emissions of a common-rail diesel engine fueled with biodiesel-methanol blend

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能源前沿 2011年第4期5卷 412-418页

作者： Wu YU Gen CHEN Zuohua HUANG State Key Laboratory of Multiphase Flow in Power Engineering Xi'anJiaotong University Xi'an 710049 China

In this paper,the effect ofcetane number (CN)improver on performance and emissions,including particulate number concentration and size distribution,of a turbocharged,common-rail diesel engine fueled with biodiesel-methanol were *** volume fractions (0.3％ and 0.6％) of CN improver were added to BM30 (30％ of methanol in the biodiesel-methanol blend) in the *** results show that,compared with those of biodiesel-methanol blend,the peak value of cylinder pressure increases,the second peak of heat release rate decreases,the start of second heat release are advanced,and the fuel economy and thermal efficiency are improved when CN improver is added to biodiesel-methanol ***,CO and HC emissions decrease,NOx emission varies little and smoke emissions increase ***,exhaust particles of BM30 mainly distribute in nanosize ***,particle number concentration decreases and peak of size distribution profile shifts toward large size direction.

关键词： biodiesel methanol common-rail (CR) dieselengine cetane number (CN) improver

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Comparison of combustion characteristics of petroleum coke and coal in one-dimensional furnace

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中国高等学校学术文摘·能源与动力工程 2010年第3期4卷 436-442页

作者： Qulan ZHOU Qinxin ZHAO Guangjie ZHOU Huiqing WANG Tongmo XU Shien HUI State Key Laboratory of Multiphase Flow of Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The effect of primary air fraction f1, outer secondary air swirl strength and excess oxygen coefficient on the combustion characteristics of petroleum coke, Hejin lean coal and Shenmu soft coal are researched on a one-dimensional furnace using a dual channel swirl burner. The results show that with the increase in primary air fraction f1, the NOx emission concentrations of both Hejin lean coal and petroleum coke increase, and the combustion worsens in the earlier stage, but the burn-out rate of Shenmu soft coal is improved. The NOx emission concentration obtains a minimum value with an increase in f1. The ignition and burn-out rate of petroleum coke and Shenmu soft coal are optimal when Ωdl is minimum and Ωdl=0.87, respectively. However, both the NOx emission concentration of petroleum coke and Shenmu soft coal are minimum when Ωdl=1.08. The increase in excess oxygen coefficient delays the ignition of petroleum coke, worsens the combustion condition and increases the NOx emission concentration, but it greatly decreases the NOx emission concentration of Shenmu soft coal.

关键词： petroleum coke Shenmu soft coal Hejin lean coal combustion characteristics experimental research

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Numerical simulation of the heat flux distribution in a solar cavity receiver

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能源前沿 2011年第1期5卷 98-103页

作者： Yueshe WANG Xunwei DONG Jinjia WEI Hui JIN State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

In the solar tower power plant, the receiver is one of the main components of efficient concentrating solar collector systems. In the design of the receiver, the heat flux distribution in the cavity should be considered first. In this study, a numerical simulation using the Monte Carlo Method has been conducted on the heat flux distribution in the cavity receiver, which consists of six lateral faces and floor and roof planes, with an aperture of 2.0m×2.0m on the front face. The mathematics and physical models of a single solar ray's launching,reflection, and absorption were proposed. By tracing every solar ray, the distribution of heat flux density in the cavity receiver was obtained. The numerical results show that the solar flux distribution on the absorbing panels is similar to that of CESA-I's. When the reradiation from walls was considered, the detailed heat flux distributions were issued, in which 49.10% of the total incident energy was absorbed by the central panels,47.02% by the side panels, and 3.88% was overflowed from the aperture. Regarding the peak heat flux, the value of up to 1196.406 kW/m2 was obtained in the center of absorbing panels. These results provide necessary data for the structure design of cavity receiver and the local thermal stress analysis for boiling and superheated panels.

关键词： solar cavity receiver Monte Carlo method heat flux distribution

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Numerical study on laminar flame speed of natural gas-carbon monoxide-air mixtures

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Frontiers of Chemical Science and engineering 2010年第4期4卷 411-416页

作者： Chen DONG Qulan ZHOU Qinxin ZHAO Tongmo XU Shi’en HUI State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Laminar flame speeds of natural gas-carbon monoxide-air mixtures are calculated by CHEMKIN II with GRI Mech-3.0 over a large range of fuel compositions,equivalence ratios,and initial *** calculated results of natural gas are compared with previous experimental results that show a good *** calculated laminar flame speeds of natural gas-carbon monoxide-air mixtures show a nonmonotonic increasing trend with volumetric fraction of carbon monoxide and an increasing trend with the increase of initial temperature of *** maximum laminar flame speed of certain fuel blend reaches its biggest value when there is 92%volumetric fraction of carbon monoxide in fuel at different initial *** stoichiometric natural gas-carbon monoxide-air mixtures are selected to study the detailed chemical structure of natural gas-carbon monoxide-air *** results show that at stoichiometric condition,the fuel blend with 80%volumetric fraction of carbon monoxide has the biggest laminar flame speed,and the C normalized total production rate of methane with 80%volumetric fraction of carbon monoxide is the largest of the five stoichiometric mixtures.

关键词： laminar flame speed numerical study nonmonotonic increasing trend

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Convective heat transfer in helical coils for constant-property and variable-property flows with high Reynolds numbers

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中国能源与动力工程前沿 2010年第4期4卷 546-552页

作者： Yufei MAO Liejin GUO Bofeng BAI Ximin ZHANG State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Forced convection heat transfer of single-phase water in helical coils was experimentally studied. The testing section was constructed from a stainless steel round tube with an inner diameter of 10?mm, coil diameter of 300?mm, and pitch of 50?mm. The experiments were conducted over a wide Reynolds number range of 40000 to 500000. Both constant-property flows at normal pressure and variable-property flows at supercritical pressure were investigated. The contribution of secondary flow in the helical coil to heat transfer was gradually suppressed with increasing Reynolds number. Hence, heat transfer coefficients of the helical tube were close to those of the straight tube under the same flow conditions when the Reynolds number is large enough. Based on the experimental data, heat transfer correlations for both incompressible flows and supercritical fluid flows through helical coils were proposed.

关键词： convective heat transfer helical coils high Reynolds number supercritical pressure variable property

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Hierarchical growth of a novel Mn-Bi coupled BiVO4 arrays for enhanced photoelectrochemical water splitting

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Nano Research 2019年第3期12卷 575-580页

作者： Lu Wang Jinzhan Su Liejin Guo International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering School cf Energy & Power Engineering Xian Jiaotong University Xian 710049 China

Oxygen evolving catalyst (OEC) is a critical determinant for the efficiency of photoelectrochemical (PEC) water splitting. Here we report an approach to depositing a novel manganese borate (Mn-Bi) OER catalyst on BiVO4 nanocone photoanode by photodeposition in sodium borate buffer solution containing Mn(Ⅱ) ions. Due to the spontaneous photo-electric-field-enhancement effect at the vertically oriented BiVO4 nanocone structure, spherical Mn-Bi nanoparticle was selectively photodeposited at the apex of BiVO4 nanocone. Significant improvement of photocurrent was observed for the obtained hierarchical Mn-Bi/BiVO4 photoanode which could be ascribed to enhanced hole injection efficiency, especially in low bias region. It was observed that the injection efficiency of Mn-Bi/BiVO4 is 98% which gave a photocurrent of 0.94 mA/cm^2 at 1.5 V vs. RHE.

关键词： bismuth vanadate photoelectrochemistry solar water splitting oxygen evolution

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Implementation of an efficient segregated algorithm-IDEAL on 3D collocated grid system

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Chinese Science Bulletin 2009年第6期54卷 929-942页

作者： SUN DongLiang QU ZhiGuo HE YaLing Tao WenQuan State Key Laboratory of Multiphase Flow in Power Engineering School of Energy & Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The segregated algorithm-IDEAL (inner doubly-iterative efficient algorithm for linked-equations) is an efficient and stable algorithm. In this algorithm, there exist inner doubly-iterative processes for pres-sure equation, which almost completely overcome two approximations in SIMPLE algorithm. Thus the coupling between velocity and pressure is fully guaranteed, greatly enhancing the convergence rate and stability of iteration process. In this paper, implementation of the IDEAL algorithm on a 3D collo-cated grid system is conducted. The interface velocity is calculated by the modified momentum inter-polation method (MMIM), by which the converged result is independent of the under-relaxation factor. Finally, five three-dimensional incompressible fluid flow and heat transfer problems are provided to compare the convergence rate and robustness between the IDEAL and three other most widely-used algorithms (SIMPLER, SIMPLEC and PISO). By the comparison it can be concluded that the IDEAL al-gorithm is more robust and efficient than the three other algorithms.

关键词：隔离算法网格系统理想 SIMPLE算法 3D 压力方程收敛速度迭代过程

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Simulation of combustion in spark-ignition engine fuelled with natural gas-hydrogen blends combined with EGR

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中国高等学校学术文摘·能源与动力工程 2009年第2期3卷 204-211页

作者： Jie WANG Zuohua HUANG Bing LIU Xibin WANG State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

A numerical simulation of the influence of different hydrogen fractions, excess air ratios and EGR mass fractions in a spark-ignition engine was conducted. Good agreement between the calculated and measured in-cylinder pressure traces as well as pollutant formation trends was obtained. The simulation results show that NO concentration has an exponential relationship with temperature and increases sharply as hydrogen is added. EGR introduction strongly influences the gas temperature and NO concentration in the cylinder. The difference in temperature will lead to even greater difference in NO concentration. Thus, EGR can effectively decrease NO concentration. NO concentration reaches its peak value at the excess air ratio of 1.1 regardless of EGR mass fraction. The study shows that natural gas-hydrogen blend combined with EGR can realize a stable combustion and low NO emission in a spark-ignition engine.

关键词： natural gas hydrogen NO exhaust gas recirculation numerical simulation

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