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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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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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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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A two-phase non-isothermal mass transport model for direct methanol fuel cells

A two-phase non-isothermal mass transport model for direct m...

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

作者： Miao, Zheng He, Ya-Ling Li, Xiao-Yue Zou, Jin-Qiang State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an Shaanxi China

ISBN: (纸本)9780791802908

A two-dimensional two-phase non-isothermal mass transport model for liquid feed direct methanol fuel cells (DMFCs) is presented in this paper. The heat and mass transfer across the membrane electrode assembly (MEA) is formulated based on the classical multiphase flow theory in the porous media. The effects of methanol crossover and non-equilibrium evaporation/condensation of methanol and water at the gas-liquid interface on the cell performance are considered. Results of this model show that the methanol feeding concentration and cell operation temperature have great effects on the cell performance. The distribution of cell temperature is non-uniform and the highest temperature appears in the cathode catalyst layer (CL). The effects of open-ratio of the flow field plate and the thermal conductivity of diffusion layers, catalyst layers and membrane are also investigated in this work. Copyright © 2009 by ASME.

关键词： Methanol

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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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Numerical study on a novel SOFC with bi-layer interconnector

Numerical study on a novel SOFC with bi-layer interconnector

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

作者： Chen, Qiuyang Zhang, Jian Wang, Qiuwang Zeng, Min State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China

ISBN: (纸本)9780791802908

Solid oxide fuel cells (SOFCs) have received considerable interest nowadays, because they promise greater electrical efficiency than that obtained by a conventional heat engine or other types of low temperature fuel cells. Validated mathematical models provide a very powerful tool for the development of improved SOFC designs and operating conditions. From some literature and numerical simulation results, it could be found that the concentration gradient of fuel and oxidant gas is great on the plane which is normal to the SOFC tri-layer, especially in the porous electrode. But the structures in the previous literature and inventions are always focusing on the disturbance of flow on the plane which is parallel to the SOFC tri-layer. In order to lower the concentration polarization of SOFC, We have invented a novel SOFC with bi-layerer interconnector which can disturb the fuel and air gas on the plane which is normal to the SOFC tri-layer and enhance the mass transfer effectively. In this paper, the primary objective is to compare the concentration overpotentials under the different interconnects modes. A 2D half-cell model has been developed to study on concentration overpotentials of fuel side of the SOFC stack with conventional interconnects and novel bi-layer *** numerical simulation results show that the novel interconnect can disturb the fuel and air gas on the plane which is normal to the SOFC tri-layer and reduce the concentration overpotential of SOFC. It can enhance the mass transfer in porous electrode and improve the performance of SOFC. Copyright © 2009 by ASME.

关键词： Mass transfer

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Performance of a domestic refrigerator using R600a/nano-TiO2 as working fluid

Performance of a domestic refrigerator using R600a/nano-TiO2...

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4th Asian Conference on Refrigeration and Air-Conditioning, ACRA 2009

作者： Bi, Shengshan Guo, Kai Liu, Zhigang Wu, Jiangtao State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an Shaanxi 710049 China

ISBN: (纸本)9868509610

In this work, an experimental work was investigated on the nano-refrigerant. A domestic R600a refrigerator was selected and instrumented with 19 resistance thermometers and three pressure transducers. R600a/TiO 2 nano-refrigerants were used as working fluid without any system reconstruction. The refrigerator performance was then investigated using energy consumption test and freeze capacity test. The results indicate that R600a/TiO2 nano-refrigerant works normally and safely in the refrigerator. The refrigerator performance was better than the pure R600a system, with 9.6% less energy used with 0.5 g/L nano-refrigerant. Thus, using R600a/ TiO2 nano-refrigerant in domestic refrigerators is feasible.

关键词： Refrigerators

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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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Equations for the thermophysical properties of dimethyl carbonate

Equations for the thermophysical properties of dimethyl carb...

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2009 AIChE Annual Meeting, 09AIChE

作者： Zhou, Yong Wu, Jiangtao State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China

Dimethyl carbonate (DMC) is a nonirritating and nontoxic chemical, further more;it can be used as a fuel additive. In this work, the thermophysical properties formulations for dimethyl carbonate has been developed based upon a selection of available experimental thermophysical property data. In determining the coefficients of the equation of state, multi-property fitting methods were used;including single-phase pressure-volume-temperature (pVT), heat capacity, vapor pressure, and saturated liquid density data. The equation of state has been developed to conform to the Maxwell criterion for two-phase liquid-vapor equilibrium states and is valid for temperatures from 280 K to 400 K and pressure to 60 MPa, and the extrapolation behavior of the equation of state at high temperatures and high pressures is reasonable. The deviation of the density (100x(ρcal-ρexp)/ρexp) is generally less than 0.1% and does not exceed 0.2% except for very few data points in liquid region. The uncertainty of the vapor pressure of the equation of state is generally less than 2.0%. The deviation of viscosity equation developed is generally less than 2.0%, and the absolute average deviation (AAD) between experimental and calculated values is 1.03%. In additional, the extended corresponding states (ECS) model with R134a as the reference fluid was used to represent viscosities and thermal conductivities, and the absolute average deviations are 1.34% and 1.47%, respectively. Detail comparisons between experimental and calculated data have been performed in the work.

关键词： Hydrostatic pressure

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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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