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Mitigating check valve slamming and subsequentwater hammer events for PPFS using MOC

Nuclear Science and Techniques 2009年第2期20卷 118-123页

作者： TIAN Wenxi SU Guanghui WANG Gaopeng QIU Suizheng XIAO Zejun State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and TechnologyXi＇an Jiaotong University Xi＇an 710049 China National Key Laboratory of Bubble Physics ＆ Natural Circulation Nuclear Power Institute of China Chengdu 610041 China

The method of characteristic(MOC) was adopted to analyze the check valve-induced water hammer behaviors for a Parallel Pumps Feedwater System(PPFS) during the alternate startup *** motion of check valve disc was simulated using inertial valve *** parameters including the pressure oscillation,local flow velocity and slamming of the check valve disc *** been *** results showed that severe slamming between the valve disc and valve seat occurred during the alternate startup of parallel *** induced maximum pressure vibration amplitude is up to 5.0 *** scheme of appending a damping torque to slow down the check valve closing speed was also performed to mitigate of water *** has been numerically approved to be an effective approach.

关键词：止回阀建设部事件水锤泵给水系统启动过程压力振动瞬态参数

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Measurement of laminar burning velocities and Markstein lengths for diethyl ether-air mixtures at different initial pressure and temperature 7

Measurement of laminar burning velocities and Markstein leng...

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7th Asia-Pacific Conference on Combustion, ASPACC 2009

作者： Di, Yage Huang, Zuohua Zhang, Ni Gu, Xiaolei Zheng, Bin Zhang, Zhiyuan State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

Measurement of laminar burning velocities and Markstein lengths were made for the diethyl ether-air mixtures at different equivalence ratios, initial temperatures and pressures by using spherically propagating flame and schlieren photography method. The results show that the stretched flame propagation speeds and unstretched laminar burning velocities are increasing with the increase of the initial temperature. While the Markstein lengths are decreased with the increase of the initial temperature. The stretched flame propagation speeds, the unstretched laminar burning velocities and Markstein lengths are decreased with the increase of the initial pressure. The Markstein lengths are decreased with the increase of the equivalence ratio. Based on the experimental data, a correlation is obtained for the unstretched laminar burning velocity versus the initial temperature and pressure over wide range of equivalence ratios. © 2009 Combustion Institute. All rights reserved.

关键词： Mixtures

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A calculation method for evaluating thermal loss of solar cavity receiver

A calculation method for evaluating thermal loss of solar ca...

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

作者： Jiabin, Fang Jinjia, Wei Xunwei, Dong Yueshe, Wang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9781424424870

One of the most important components of solar thermal power system is the solar central receiver, which performance is in direct relation to the efficiency of the whole power generation system. The calculation of internal surface heat flux and thermal efficiency of receiver therefore plays a very important role in receiver design. A calculation method of heat loass of a cavity receiver is put forward in this paper. The first step of this method is to use the Monte Carlo method to simulate the track of solar beam and compute surface heat flux inside the receiver. The second step is to employ the correlations of flow boiling heat transfer to figure out the convective heat transfer coefficient inside the tubes and then the wall temperature of the boiling tubes laid inside the receiver. The last step is to simulate the air flow field inside the receiver to calculate convective thermal loss of the receiver. As every step can not be independently done, all steps are coupled and an iterative scheme is needed. Internal surface heat flux and thermal efficiency of the receiver can be finally gained with this method, and the result can provide theoretical guide for receiver design. © 2009 IEEE.

关键词： Monte Carlo methods

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Characteristics of HCN removal using cao at high temperatures

Characteristics of HCN removal using cao at high temperature...

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作者： Houzhang, Tan Xuebin, Wang Congling, Wang Tongmo, Xu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniVersity Shaanxi 710049 China

Experimental investigation on the removal of hydrogen cyanide (HCN) using calcium oxide (CaO) was carried out in a fixed bed reactor at temperature ranging from 300 to 1173 K, and the original HCN was produced during the pyrolysis of pyridine. Effects of temperature, volume space velocity, and initial HCN concentration on HCN removal were discussed. The results of temperature-programmed experiments show that temperature is the main factor affecting HCN removal. With the formation of CO, HCN starts to decrease from 473 K, and remains unchanged from 673 to 873 K. At 873 K, there is a further decrease in HCN without CO formation, and when temperature is higher than 1023 K, HCN is removed completely. In the isothermal experiments, CaCN2 was detected at 723 K, but at higher temperatures of 923 and 1123 K, there was no CaCN2 in the solid residues, and the nitrogen in the removed HCN was equal to that in the formed N2. This indicates that at a lower temperature CaO is consumed to remove HCN, CaO + 2HCN f CaCN2 + CO + H2;but at a higher temperature, CaO acts as a catalyst for HCN removal, 2CiHj + 2HCN f N2 + (j + 1 - k)H2 + 2Ci+1Hk. The investigation on the removal efficiency shows that there is a critical temperature and a critical volume space velocity at which the HCN removal efficiency is able to reach up to 100%. © 2009 American Chemical Society.

关键词： Temperature

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Effect of partially premixed and hydrogen addition on lean burn natural gas direct injection combustion 7

Effect of partially premixed and hydrogen addition on lean b...

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7th Asia-Pacific Conference on Combustion, ASPACC 2009

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

Effect of partially premixed and hydrogen addition on lean burn natural gas direct injection combustion was studied experimentally using a constant volume vessel. Flame propagating photos and pressure derived combustion parameters were analyzed at different premixed ratios (from 0% to 80%) and hydrogen fractions (from 0% to 40%) at overall equivalence ratio of 0.6 and 0.8, respectively. The results showed that the flame kernel was concentrated to the spark position with the increase of premixed ratio and/or hydrogen fraction. The flame propagating speed was increased with hydrogen addition to natural gas. The stable spark ignition of lean burn natural gas was realized with the combination of partially premixed direct injection combustion and hydrogen addition. Both the initial and main combustion durations were increased with the increase of premixed ratio, while they showed the decreasing trend with hydrogen addition to natural gas. Partially premixed direct injection combustion combing with hydrogen addition can achieve the stable spark ignition and fast combustion rate at the lean mixture condition. © 2009 Combustion Institute. All rights reserved.

关键词： Natural gas

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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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Measurements of premixed laminar burning velocities and Markstein lengths for isooctane-air-N2 mixtures 7

Measurements of premixed laminar burning velocities and Mark...

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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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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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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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