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7th Asia-Pacific Conference on Combustion, ASPACC 2009

作者： Ran, F. Wang, X.B. Zhu, R.J. Zhang, Z.Y. Xiang, J. Huang, Z.H. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Experiments on the laminar burning velocities and Markstein lengths for the isooctane-air-N2 blends using a constant volume combustion chamber and a high-speed schlieren photography system have been performed under different equivalence ratios, initial pressures and temperatures, and dilution ratios to determine the effect of these parameters on the laminar burning velocities. The results suggest that an decrease in initial pressure or dilution ratio and an increase in initial temperature lead to an increase in the laminar burning velocity;an increase in initial pressure and initial temperature lead to a decrease in the Markstein length. © 2009 Combustion Institute. All rights reserved.

关键词： Velocity

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Effects of hydrogen addition on cellular instabilities of the spherically expanding propane flames 7

Effects of hydrogen addition on cellular instabilities of th...

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7th Asia-Pacific Conference on Combustion, ASPACC 2009

作者： Tang, C.L. Huang, Z.H. Wang, J.H. Zheng, J.J. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

An experimental study on the effects of hydrogen addition on the instabilities of spherically expanding propane-air flames was conducted in a constant volume combustion vessel over a wide range of mixture compositions and initial temperatures and pressures. The measured laminar burning velocities were compared with those of the calculated one dimensional freely propagating flames, using a recently developed detailed kinetic mechanism, and the agreement was excellent. The schlieren images show that for the fuel lean conditions, hydrogen addition increases the hydrodynamic instability due to the decreased flame thickness and increases diffusional-thermal instability due to the decreased Lewis number, while for the fuel rich conditions, the flame front is initially destabilized and later stabilized with the increase of hydrogen fraction as the results of the competing effects of hydrodynamic and diffusional-thermal instabilities © 2009 Combustion Institute. All rights reserved.

关键词： Propane

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Effect of hydrogen addition on early flame growth of lean burn natural gas-air mixtures 7

Effect of hydrogen addition on early flame growth of lean bu...

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7th Asia-Pacific Conference on Combustion, ASPACC 2009

作者： Wang, J.H. Huang, Z.H. Tang, C.L. Zheng, J.J. State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Effect of hydrogen addition on early flame growth of lean burn natural gas-air mixtures was investigated experimentally and numerically. The flame propagating photos and pressure derived initial combustion duration of premixed combustion and direct injection combustion was obtained by using a constant volume vessel. The laminar premixed methane-hydrogen-air flames were calculated with PREMIX code of CHEMKIN II program with GRI 3.0 mechanism. The results showed that the early flame growth of lean burn natural gas-air mixtures was enhanced as hydrogen is added to natural gas in the case of both premixed combustion and direct injection combustion. The mole fraction of OH and O are increased with the increase of hydrogen fraction and the position of maximum OH and O mole fraction move closing to the unburned mixture side. A monotonic correlation between initial combustion duration with the reciprocal maximum OH mole fraction in the flames is observed. The enhancement of the spark ignition of natural gas with hydrogen addition can be ascribed to the increase of OH and O mole fraction in the flames. © 2009 Combustion Institute. All rights reserved.

关键词： Natural gas

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Study of low-pressure premixed laminar n-heptane+propane/oxygen/nitrogen flames

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Chinese Science Bulletin 2009年第9期54卷 1477-1486页

作者： YU Wu WEI LiXia MA ZhiHao HUANG ZuoHua YUAN Tao TIAN ZhenYu LI YuYang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230029 China

Low-pressure premixed laminar n-heptane+propane/oxygen/nitrogen flames were investigated with tunable synchrotron vacuum ultraviolet (VUV) photoionization and molecular-beam sampling mass spectrometry. Three flames with different mass percentage of propane in the fuel blends of 0%, 10%, and 20% were studied. The combustion intermediates were identified by comparing the measured IEs with those values in literatures. Mole fraction profiles of the main species were compared among the three flames. The experimental results provide detailed data in understanding the combustion of n-heptane and n-heptane/propane blends in engine. They are also helpful in establishing and verifying the kinetic models.

关键词：正庚烷火焰丙烷混层低压氮氧真空紫外

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Effect of metal oxide on the emission of N2O and NO in fluidized bed temperature range using pyridine as a nitrogenous model fuel

Effect of metal oxide on the emission of N2O and NO in fluid...

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20th International Conference on Fluidized Bed Combustion

作者： Wang, X.B. Tan, H.Z. Wang, C.L. ZhaoQ.X. Xu, T.M. Hui, S.E. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Pyridine has been chosen as the nitrogenous model fuel to research the effect of metal oxide (CaO, MgO and Fe2O3) on the emission of nitrogen oxides in the range of fluidized bed combustion temperature. The experiment was presented in a fixed bed reactor with metal oxide layer, and FT-IR gas analyzer was used to monitor the emission of N2O and NO. When there is no metal oxide loaded, results show that the maximum peak of N2O is at 725°C. Under the rich oxygen condition, NO increases monotonically with temperature increasing, however, under the lean oxygen condition there is a maximum peak of NO at 675°C, NO decreases to a minimum value at 725°C, and then increases slowly. With the addition of metal oxide, the loaded experimental results show that the addition will not change the general trend of nitrogen oxides, but it affects the emission in a certain extent and the effect has relation to temperature, oxygen atmosphere and metal oxide added. Under the lean oxygen condition, both CaO and Fe2O 3 inhibit the formation of N2O and NO in all temperature range;the effect of Fe2O3 on NO is negligible above 900°C;MgO inhibits N2O at temperature higher than 725°C, and inhibits NO only from 625°C to 700°C. Under the rich oxygen condition, CaO and MgO decrease the N2O emission efficiently, but Fe 2O3 can only act at the temperature higher than 700°C. For the NO emission, CaO and MgO inhibit NO just above 775°C, however, Fe2O3 promotes NO greatly especially below 700°C, and it even promotes NO2 to 122.65ppm at 625°C. The results and discussion are helpful to demonstrate the effect of metal elements on the emission of nitrogen oxides in fluidized bed combustion.

关键词： Fluidized beds

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New technology of thermodynamic cycle for waste heat recovery of vehicle gasoline engine

New technology of thermodynamic cycle for waste heat recover...

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2009 Asia-Pacific power and Energy engineering Conference, APPEEC 2009

作者： Zhang, Xin-Xin Zeng, Ke He, Mao-Gang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi China

ISBN: (纸本)9781424424870

In this paper, the exothermic distribution of fuel was studied detailedly through conducting thermal equilibrium experiment when the vehicle gasoline engine was at different working conditions. Considering the characteristic of the exhaust temperature of the vehicle gasoline engine, the Organic Rankine Cycle (ORC) was adopted for the exhaust recovery. The thermodynamic parameter and thermodynamic performance of the main state points in the ORC were theoretically calculated via computer program. The optimal parameter was determined. On this basis, the organic working fluids were selected. In the last part, a new thermodynamic cycle configuration which can be used to recover the heat from exhaust gas, cooling water and lubricant of vehicle gasoline engine was put forward and introduced. © 2009 IEEE.

关键词： Waste heat utilization

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Numerical study on the coupled heat transfer performance of the parabolic solar absorber tube

Numerical study on the coupled heat transfer performance of ...

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2009 US-EU-China Thermophysics Conference - Renewable Energy, UECTC'09

作者： Tao, Y.B. He, Y.L. State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China

ISBN: (纸本)9780791802908

In present paper, a two-dimensional numerical model for the coupled heat transfer process in the solar collector tube was developed and the unified dimensionless governing equations were derived. The full field computation method was adopted to deal with the fluid-solid conjugated heat transfer problem. The effects of Ra numbers and tube diameter ratio on the heat transfer and fluid flow performance were numerically analyzed under the constant heat flux conditions. The distributions of flow field, temperature field, local Nu and local temperature gradient were examined. The results show that when Ra is larger than 105, the effects of nature convection must be taken into account. Due to the effect of the nature convection, along the θ direction, the temperature in the cross-section decreases and the temperature gradient on the inner tube surface increases at first. When θ is near to π, the temperature and temperature gradients would present a converse variation. The local Nu on the inner tube surface increases along θ direction until it reaches a maximum then it decreases again. Due to the existing of the nature convection vortexes, the temperature distributions in some cross-sections present fluctuations along the r direction. Copyright © 2009 by ASME.

关键词： Heat flux

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Numerical study of heat transfer characteristics in the solar receiver tube combined with MCRT method

Numerical study of heat transfer characteristics in the sola...

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2009 US-EU-China Thermophysics Conference - Renewable Energy, UECTC'09

作者： Cheng, Z.D. He, Y.L. Xiao, J. Tao, Y.B. Xu, R.J. State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an Shaan xi China

ISBN: (纸本)9780791802908

The solar energy flux distribution on the outer wall of the inner absorber tube of parabolic solar collector receiver is calculated successfully by a homemade code adopting Monte Carlo Ray-Trace Method (MCRT Method). It is revealed that the non-uniformity of the solar energy flux distribution is very large. Three-dimensional numerical simulation of coupled heat transfer characteristics in the receiver tube is calculated and analyzed by combining the MCRT Method and the FLUENT software, in which the heat transfer fluid and physical model are Syltherm 800 liquid oil and LS2 parabolic solar collector from the testing experiment of Dudley et al., respectively. Temperature- dependent properties of the oil and thermal radiation between the inner absorber tube and the outer glass cover tube are also taken into account. Then three typical testing conditions are chosen from the experiment to validate the reliability of the simulation code. Numerical results show that the predicted results agree well with the experimental data, the average relative error is within 2%. And then the mechanism of the coupled heat transfer in the receiver tube is further studied. Copyright © 2009 by ASME.

关键词： Numerical methods

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Experimental study of nitrogen oxide emissions in a circulating fluidized bed

Experimental study of nitrogen oxide emissions in a circulat...

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20th International Conference on Fluidized Bed Combustion

作者： Liu, R.W. Zhou, Q.L. Hui, S.E. Xu, T.M. State Key Laboratory of Power Engineering Multiphase Flow Department of Energy and Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China

The experimental study was carried out on the emission characteristics of nitrogen oxide in a 0.3MW circulating fluidized bed as well as analysis of the formation and destruction mechanism of nitrogen oxide. Several variables associated with the combustion system were investigated in the experiment, which include bed temperature, excess air, primary-to-secondary air ratio, and coal species. It is found that the NOx emissions decrease along the height of the furnace, while the N2O emissions increase continuously. More NOx emissions and less N2O emissions are generated as the bed temperature increases. It is also illustrated that an increase of air stoichiometry leads to a significant NOx increase and an obvious N2O increase. And air staging is proved to be an effective way to control the nitrogen oxide emissions in the fluid bed. Besides, it is also shown in the experiment that the concentration of NOx and N2O is higher during the combustion of anthracite than that during the combustion of bituminous.

关键词： Nitrogen oxides

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Lattice Boltzmann method and its applications in engineering thermophysics

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Chinese Science Bulletin 2009年第18期54卷 4117-4134页

作者： HE YaLing LI Qing WANG Yong TANG GuiHua School of Energy and Power Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049 China

The lattice Boltzmann method (LBM), a mesoscopic method between the molecular dynamics method and the conventional numerical methods, has been developed into a very efficient numerical alternative in the past two decades. Unlike conventional numerical methods, the kinetic theory based LBM simulates fluid flows by tracking the evolution of the particle distribution function, and then accumulates the distribution to obtain macroscopic averaged properties. In this article we review some work on LBM applications in engineering thermophysics: (1) brief introduction to the development of the LBM; (2) fundamental theory of LBM including the Boltzmann equation, Maxwell distribution function, Boltzmann-BGK equation, and the lattice Boltzmann-BGK equation; (3) lattice Boltzmann models for compressible flows and non-equilibrium gas flows, bounce back-specular-reflection boundary scheme for microscale gaseous flows, the mass modified outlet boundary scheme for fully developed flows, and an implicit-explicit finite-difference-based LBM; and (4) applications of the LBM to oscillating flow, compressible flow, porous media flow, non-equilibrium flow, and gas resonant oscillating flow.

关键词：格子玻尔兹曼方法工程热物理格子Boltzmann 麦克斯韦分布函数分子动力学方法可压缩流动应用数值方法

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