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Mass exchange network synthesis using exergoeconomic method

Mass exchange network synthesis using exergoeconomic method

26th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2013

作者： Dong, Ruifeng Zhang, Tingting Yu, Yunsong Zhang, Zaoxiao State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an 710049 China

Mass exchange network (MEN) is an important part of chemical process. Many methods have already been developed for MEN synthesis to increase the producting efficiency, such as minimizing material consumption, optimizing total annualized cost and so on. However, the energy utilization of MEN has scarcely been studied before. This paper introduces exergoeconomic analysis to MEN synthesis. The integrated analysis of energy and economic factors could provide a better guidance for production operation. The most important merit of exergoeconomic analysis is that the MEN synthesis can be further integrated with the energy exchange networks, such as heat and pressure exchange networks. Therefore, the feasibility of exergoeconomic method used in MEN synthesis is studied. A case study of water network synthesis is carried out to reveal the feasibility of exergoeconomic analysis in optimizing MEN. The optimization turns out to be a mixed integer nonlinear programming (MINLP) problem because of the multi-objective and multiconstraint factors. Genetic algorithm (GA) is employed to get a globally optimal solution based on MATLAB program. The calculation shows that the result of MEN exergoeconomic analysis is basically consistent with that of waste minimization, with a little difference according to the energy and economic factors. Therefore, exergoeconomic analysis is proved to have a good performance in solving mass exchange network synthesis problems.

关键词： Genetic algorithms

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Effect of equivalence ratio on the ignition delay times of propane/hydrogen in argon diluted oxygen

Effect of equivalence ratio on the ignition delay times of p...

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9th Asia-Pacific Conference on Combustion, ASPACC 2013

作者： Tang, Chenglong Man, Xingjia Pan, Lun Huang, Zuohua State Key Laboratory of Multiphase Flows in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

By using the shock tube facility, measurements on ignition delay times of propane/hydrogen mixtures (hydrogen fraction from 0 to 100%) were conducted for the equivalence ratio of 0.5, 1.0 and 2.0. Results show that for XH2 less than 70%, ignition delay time shows a strong Arrhenius temperature dependence, and the ignition delay time increases with the increase of the equivalence ratio. When XH2 is increased to more than 95%, the ignition delay times do not retain the Arrhenius temperature dependence any more, and the effect of the equivalence ratio is very weak. Numerical studies were made using the selected kinetic mechanisms and results show that the predicted ignition delay time gives a reasonable agreement with the measurements at all test conditions. Both measurements and predictions show that for X H2 less than 70%, the ignition delay time is only moderately decreased with the increase of XH2, indicating that hydrogen addition has weak effect on ignition enhancement. Sensitivity analysis reveals the key reactions that control the simulation of ignition delay time. Kinetic study is made to interpret the ignition delay time dependence on equivalence ratio and XH2.

关键词： Hydrogen

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Measurement of the instantaneous detailed flame front structure of syngas turbulent premixed flames at high pressure

Measurement of the instantaneous detailed flame front struct...

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9th Asia-Pacific Conference on Combustion, ASPACC 2013

作者： Wang, Jinhua Zhang, Meng Huang, Zuohua Kudo, Taku Kobayashi, Hideaki State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Institute of Fluid Science Tohoku University Sendai Miyagi 9808577 Japan

Instantaneous detailed flame front structure of syngas turbulent premixed flames was investigated and compared to that of CH4/air flames. Results show that the flame front of turbulent premixed flames at high pressure is a wrinkled flame front with small scale convex and concave structures superimposed with large scale flame branches. The convex structures are much more frequent than the concave ones on flame front which reflects a general characteristic of the turbulent premixed flames at high pressure. The syngas flames possess much wrinkled flame front with much smaller fine cusps structure compared to that of CH4/air flames and the main difference is on the convex structure. The effect of turbulence on the general wrinkled scale of flame front is much weaker than that of the smallest wrinkled scale. The general wrinkled scale is mainly dominated by the turbulence vortex scale, while, the smallest wrinkled scale is determined by the flame intrinsic instability. The effect of flame intrinsic instability on flame front of turbulent premixed flame is mainly on the formation of a large number of convex cusps structure propagating to the unburned reactants and enlarge the effective contact surface between flame front and unburned reactants.

关键词： Turbulence

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Experimental study on boiling heat transfer and two-phase frictional pressure drop characteristics of glycol-water solution in a vertical porous surface tube

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AIP Conference Proceedings 2013年第1期1547卷 390-399页

作者： Shouxu Qiao Haijun Wang Hongfang Gu Yushan Luo Lei Zhang Wei Xiong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 710049 Xi'an China

Although much research has been conducted on investigating the flow boiling heat transfer of low saturation temperature refrigerants, there are few experimental data and theory about the flow boiling heat transfer of high saturation temperature organic mixture which exists widely in the petrochemical industry. To investigate the characteristics of flow boiling heat transfer of high saturation temperature organic mixture, experiments of glycol-water solution flow boiling in a vertical porous surface tube and a vertical smooth tube are conducted. Test tubes are uniformly heated by electrical current with a heated length of 2,000 mm. The mass flux in the experiment ranges from 500 to 1,500t⋅h−1 and the heat flux on test tubes ranges from 10 to 40 kW⋅m−2. The flow boiling heat transfer coefficients and two-phase frictional pressure drops of the two types of tubes are obtained and compared. The results indicate that: the flow boiling heat transfer coefficient in the porous surface tube is 3.8∼5.7 times of that in smooth tube and the pressure drop of the porous surface tube is 0.99∼1.007 times of that in the smooth tube. The physical mechanisms of the enhanced heat transfer characteristics of flow boiling in the porous surface tube are analyzed. By the regression analysis of the experimental data, correlations predicting the flow boiling heat transfer coefficient and pressure drop of glycol-water solution within the error range of ±20% are established. The experimental results can be used to guide the design of heat exchange equipment using the porous surface tube as heat transfer elements under these test conditions.

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Investigation on the impact of the environment wind velocity on the indirect air-cooling tower performance

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AIP Conference Proceedings 2013年第1期1547卷 469-476页

作者： Yongbo Qin Hongfang Gu Haijun Wang Guoyong Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 710049 Xi'an China

The wind velocity plays a crucial role in the operation characteristic of indirect cooling tower. In this paper a 2×330MW vertical arrangement indirect air-cooled system was taken as research object, and numerical simulation method was used to analyze the relative influence of the wind speed, ranging from 4m/s to 18m/s, on the outlet water temperature of cooling tower, the outlet air temperature of radiator, the facing wind speed of the fan segment and on the outlet air speed of the cooling tower. The result shows that the impact of the natural wind speed on the cooling tower efficiency varies greatly and this impact increases as the wind speed increases.

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Study on heat transfer characteristic of ethanol-water mixture condensation on a vertical micro-tube

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AIP Conference Proceedings 2013年第1期1547卷 362-372页

作者： Xiping Chen Jinshi Wang Junchao Qin Daotong Chong Junjie Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 710049 Xi'an China

In present experiment, the vapor mixture with different velocities (2m⋅s−1, 4m⋅s−1) and different ethanol mass fraction (0.5%, 1%, 2%, 5%, 10%, 20%, 50%) flew through vertical micro-tube and condensed on the outer tube surface at pressure 31.16kPa, 47.36kPa. The condensation modes were observed by CCD camera, and the characteristics of the heat transfer coefficients versus the vapor-to-surface temperature differences for different experimental conditions were obtained. The condensation heat transfer coefficients of vapor mixture decrease with the vapor concentration increasing. The maximum peak value of heat transfer coefficients, up to 39 kW⋅m−2⋅K1, which was about 3-4 times greater than that of steam, appeared when the ethanol mass fraction was 2%. A heat transfer coefficient correlation including the effects of all the tested parameters is proposed by using the multiple linear least squares method based on the experimental data. The calculated values agreed well with the experimental data and the deviations between them were from −20% to 20%.

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Optimization research on the structure of horizontally-arranged indirect air-cooling tower under strong wind condition

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AIP Conference Proceedings 2013年第1期1547卷 454-462页

作者： Guoyong Chen Hongfang Gu Haijun Wang Yongbo Qin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 710049 Xi'an China

Strong wind has a significant impact on the heat radiation of the air-cooling system. In this research, a numerical calculation model of 2×1000MW horizontally arranged air-cooling tower is established to simulate the flow distribution and heat exchanging capability of three different structures-horizontally-arranged indirect air-cooling tower, tower with guide wall outside, and tower with a cross wall inside-under high-speed wind and extreme-speed wind conditions. The result reveals that the structure with the guide wall outside the tower only works under strong wind condition while the structure with cross wall inside shows the anti-wind capability under both high-speed wind and extreme-speed wind conditions.

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Visualization and flow boiling heat transfer of hydrocarbons in a horizontal tube

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AIP Conference Proceedings 2013年第1期1547卷 432-441页

作者： Zhuqiang Yang Qincheng Bi Yong Guo Zhaohui Liu Jianguo Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Visualizations of a specific hydrocarbon fuel in a horizontal tube with 2.0 mm inside diameter were investigated. The experiments were conducted at mass velocity of 213.4, 426.5 and 640.2 kg/ (m2⋅s), diabatic lengths of 140, 240 and 420 mm under the pressure from 2.0-2.7 MPa. In the sub-pressure conditions, bubbly, intermittent, stratified-wave, churn and annular flow patterns were observed. The frictional pressure drops were also measured to distinguish the patterns. The development of flow patterns and frictional pressure drop were positively related to the mass velocity and the heat flux. However, the diabatic length of the tube takes an important part in the process. The residence time of the fluid does not only affect the transition of the patterns but influence the composition of the fuel manifested by the fuel color and carbon deposit. The special observational phenomenon was obtained for the supercritical pressure fluid. The flow in the tube became fuzzier and pressure drop changed sharply near the pseudocritical point. The flow boiling heat transfer characteristics of the hydrocarbons were also discussed respectively. The curve of critical heat flux about onset of nucleate boiling was plotted with different mass velocities and diabatic tube lengths. And heat transfer characteristics of supercritical fuel were proved to be better than that in subcritical conditions.

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A kinetic modeling study of high temperature chemistry of n-pentanol 8

A kinetic modeling study of high temperature chemistry of n-...

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8th US National Combustion Meeting 2013

作者： Li, Qianqian Merchant, Shamel S. Green, William H. Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'n Jiaotong University Xi'an710049 China Department of Chemical Engineering Massachusetts Institute of Technology CambridgeMA02139 United States

ISBN: (纸本)9781627488426

With increasing environmental deterioration and energy demand, studies on new alternative fuels have been attracting more attention. N-pentanol is a five carbon, straight-chain alcohol, which can be produced through natural microbial fermentation and/or engineered microorganisms. It has many advantages over lower carbon alcohols, including higher energy density, lower vapor pressure and better fuel compatibility. In this study, a detailed reaction mechanism of n-pentanol, on the basis of a previously proposed n-butanol mechanism, is generated using the open-source software Reaction Mechanism Generator (RMG). High temperature chemistry of the mechanism was validated against recently published laminar flame speeds and ignition delays. Encouraging results between simulations and experiments were observed under most conditions. Simulations were also conducted using a recently developed n-pentanol oxidation mechanism (NUI model) by Heufer et al. For lean mixtures, the two mechanisms show similar results, while the RMG model yields better predictions for rich mixtures and at an elevated pressure. Reaction pathways and sensitivity analysis reveal the key differences between the two mechanisms in terms of intermediates formed and fuel consumption.

关键词： Alternative fuels

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Experimental study on performance and emissions of diesel/n-pentanol blends on a DI diesel engine

Experimental study on performance and emissions of diesel/n-...

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9th Asia-Pacific Conference on Combustion, ASPACC 2013

作者： Wei, Liangjie Cheung, C.S. Huang, Zuohua Department of Mechanical Engineering Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

In this work, experiments were conducted on a diesel engine fueled with n-pentanol/diesel blends to examine the effect of n-pentanol addition on the engine performance and emissions. Results show that, the addition of n-pentanol to diesel increases the brake specific fuel consumption and has little effect on the brake thermal efficiency. Additionally, the emissions of HC, CO and NOx are slightly increased with the increase of n-pentanol in the fuel blends, however, the particulate matter emission is significantly reduced.

关键词： Brakes

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