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Experimental investigation on flash evaporation related to pipe leakage

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Experimental investigation on flash evaporation related to p...

作者： Cai, Benan Zhang, Qi Weng, Yu Gu, Hongfang Wang, Haijun State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Pipelines such as the surge line and main pipe are easily subjected to thermal stratification and thermal fatigue as a result of the nonuniform temperature distribution in the nuclear power plants. When the surge line or main pipe subjected to thermal stratification and thermal fatigue keeps operating for long time, the pipe leakage may happen due to the existence of pipeline crack. When the fluids with high temperature and pressure leak in the crack, the water will evaporate quickly, which means this process belongs to spray flash evaporation process. The flash evaporation related to pipe leak was experimentally studied in the paper. The experiment was carried out under high temperature and high pressure with low spray rate. The temperature and relative humidity (T&H) variations over time were monitored in the experiment with installing T&H detectors. The T&H variations at different measurement positions and with different spray rates were analyzed, respectively. In addition, the effect of the dimensionless parameters including the Weber number and Jakob number was also investigated. Results indicated that the response speed increased with the increase of the spray flow rate. Higher Weber number and higher Jakob number led to higher evaporation rate. The slight pipe leakage can be predicted by using the (T&H) in the hazardous areas. Copyright © 2020 by ASME

关键词： Nuclear fuels

Inverse Analysis of Radiative Properties of Internal Medium and Surface for Cylindrical System Using Csm-Cgm Approach

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SSRN 2023年

作者： Zhang, Chao Li, Ben-Wen Zhou, Rui-Rui Li, Pan-Xin Huang, Ling-Yun Key Laboratory of Ocean Energy Utilization and Energy Conservation Ministry of Education School of Energy and Power Engineering Dalian University of Technology Dalian116024 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization Faculty of Land Resource Engineering Kunming University of Science and Technology Kunming650093 China

An inverse analysis is conducted to simultaneously estimate the radiative properties in a 2D cylindrical system including the extinction coefficient, scattering albedo, and the wall emissivity from the knowledge of the radiative heat flux over different boundaries. In which the collocation spectral method (CSM) is developed to solve the forward problem, the conjugate gradient method (CGM) is employed to solve the inverse problem, and the complex-variable-differentiation method is used to treat the sensitivity problem, separately. Meanwhile, the effects of measurement errors, initial values, and imaginary values of complex variables on the precision of the inverse analysis are investigated. Results show that the proposed inverse analysis can successfully retrieve the unknown radiative physical properties of 2D cylindrical system. Under the same physical properties, good inversion results can be obtained by using different wall (end walls and side wall) radiative heat fluxes, but the inversion efficiency from sidewall radiative heat flux is higher. Besides, it is found that, the inversion for the scattered participating medium is more efficient than that for the non-scattered participating medium;the true values and iterative convergence values have little effect on the inversion result;the influence of the initial values and the imaginary values of the complex variable on the inversion cannot be ignored. © 2023, The Authors. All rights reserved.

关键词： Conjugate gradient method

Dynamic modeling of an air-cooling supercritical power plant under temp oral variant ambient conditions 7

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Dynamic modeling of an air-cooling supercritical power plant...

7th International Conference on power engineering, ICOPE 2019

作者： Yan, Wenchen Han, Xiaoqu Chen, Nana Wu, Wenxiang Zhou, Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Air-cooling systems are widely used in coal-fired power plants, especially in areas rich in coal resources and short of water. To prompt its economic and safe operation, dynamic modeling is urgently required to acquire the power plant's characteristics under complex working conditions. In particular, the condensing pressure of the air-cooling unit is significantly affected by the ambient temperature, and the thermal power plant is a complicated energy system with serious nonlinearity. In many cases, it is difficult to establish the mathematical model of the system by traditional analytical methods. In the present work, a 1000 MW supercritical power plant thermal system was modeled and simulated by GSE simulation software. The model was developed according to the structural characteristics, incorporating boiler system, steam turbine system and direct air-cooling system. The simulation results were compared with the actual operation data of the power plant to validate the model. The relative errors of the simulation models under steady-state conditions were less than 3%, which indicates that the models have high accuracy. On this basis, the influence of condensing pressure on the standard coal consumption rate was obtained. It was shown that when the condensing pressure ranged between 5 kPa and 20 kPa, the coal rate increased by 1.6 g/kW∙h with 1 kPa increase in the condensing pressure. Then the boundary conditions of the system were changed. When the parameters changed, the changes of condensing pressure and power were monitored, so as to study the dynamic characteristics of the system. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Coal

Numerical study on drop-on-demand droplet formation dynamics 7

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Numerical study on drop-on-demand droplet formation dynamics

7th International Conference on power engineering, ICOPE 2019

作者： Zhu, Maoguo Chong, Daotong Zhao, Quanbin Chen, Weixiong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Inkjet printing technology has been applied in many industrial fields for its significant usefulness. The drop-on-demand droplet formation dynamics was studied numerically based on the VOF and CSF method. Droplet formation was modeled by imposing a vertical velocity pulse waveform perturbation. The effects of printhead geometry and fluid properties on droplet ejection stability were analyzed. Simulation results make clear that choosing an appropriate printing fluid with relatively lower density and viscosity or higher surface tension can improve the droplet ejection stability. Designing the printhead with a larger inclination of outlet is also a key way to improve the droplet ejection stability. In addition, droplet ejection stability becomes better as Z increased or Ca decreased. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Stability

Heart, a Specific Code for Thermal-Electrical Analysis of Heat Pipe Cooled Nuclear Reactor

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SSRN 2022年

作者： Zhang, Zeqin Wang, Chenglong Guo, Kailun Huang, Jinlu Qiu, Suizheng Su, Guanghui H. Tian, Wenxi School of Nuclear Science and Technology Shanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China

Heat pipe cooled reactor (HPR) features high power density, compact structure, long operation life and high reliability, which is an excellent candidate for small nuclear power source for deep space or underwater missions. In this paper, a conceptual Nuclear Silent Thermal-Electrical Reactor (NUSTER) is preliminarily designed, using 109 sodium heat pipes for passive cooling. The thermoelectric generators (TEGs) are employed in the reactor to convert fission heat to electric power. Based on the design, a HEat pipe cooled Advanced Reactor Transient analysis code (HEART) is developed, including point reactor kinetics model, multi-channel model, core heat transfer model, heat pipe model, thermoelectric generator model and coolant model. The models proposed in HEART are preliminarily verified against the design value and experiment data, and the maximum deviation is less than 12.3%. Steady-state performance of the NUSTER are successfully predicted by HEART, and results indicate that the solid-state core has good temperature flattening ability. The surface temperature of the heat pipe is less than 1300K, and the average temperature drop of the TEG module in central channel is 724.1K, which can produce an electrical power of 301.94W. The models developed in HEART can also be applied to other heat pipe cooled reactors, providing valuable experience in design and thermal-hydraulic evaluation of HPRs. © 2022, The Authors. All rights reserved.

关键词： Transient analysis

Design and Optimization of the Heat Transport and Passive Residual Heat Removal System for Fluoride-Salt-Cooled High-Temperature Advanced Reactor (FuSTAR)

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SSRN 2022年

作者： Li, Xinyu Zhang, Dalin Lv, Xindi Zhou, Xingguang Tian, Wenxi Qiu, Suizheng G.H. State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China

The new generation of reactor technology: Fluoride-Salt-cooled high-Temperature Advanced Reactor (FuSTAR), mainly applied to the steady supply for stable electricity and high-temperature process heat for remote, underground, and arid areas, has an urgent need for a scheme of the heat transport system and Passive Residual Heat Removal System. Given the complexity and consistency of the design, a unified design and optimization method is required, which can directly obtain detailed configurations and dimensions. In this paper, a design and optimization method - Multi-Layer Nonlinear Programming was proposed to obtain the optimal parameters, including vital thermodynamic values, the dimensions of heat exchangers, the configurations of pipelines, and the optimal equivalent parameters in the transient simulation. Finally, based on Multi-Layer Nonlinear Programming, the effectiveness of the Passive Residual Heat Removal System was demonstrated by the deterministic safety analysis. The detailed parameters of the Passive Residual Heat Removal System in this paper can provide the references for subsequent experimental verification. Moreover, for any reactor relying on a heat transport system, researchers can directly obtain its excellent preliminary configurations by this method avoiding a lot of iteration and conflict design, which is conducive to the integrated modeling and simulation of a new generation of reactors. © 2022, The Authors. All rights reserved.

关键词： Nonlinear programming

Comparison of Lifetime Performance of Pemfc Stacks with Two Cooling Strategies Under Different Humidity

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SSRN 2024年

作者： Yang, Yunjie Bai, Minli Zhou, Zhifu Wu, Wei-Tao Lv, Jizu Hu, Chengzhi Li, Yang Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing210094 China School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China

While reducing the size and Pt loading can achieve a lower proton exchange membrane fuel cell (PEMFC) stack cost, it is also very important to focus on the performance changes of the PEMFC stack during the long-term operation. A 3D PtCo catalysts long-term performance model is established in this study, and PEMFC stacks with one cooling unit per cell (1-cell stack) and three cells (3-cell stack) are employed as the computational domains, respectively. The effective area of each cell is 50 cm2, and the changes in current density as well as effective catalytic area of PEMFC stacks with two cooling strategies before and after long-term operation under different humidity conditions are investigated at low Pt loadings. The results show that there are large differences in the output voltage and current density distributions between the three cells due to the poor membrane hydration affected by the non-uniform temperature distribution, although the 3-cell stack can significantly reduce the size. Localized catalyst degradation in both 3-cell and 1-cell stacks is closely related to the geometry of the cathodic flow field, and non-uniform catalyst degradation is found to increase the activation and mass transfer losses and change the distribution of current density within the membrane. In addition, the 3-cell stack is found to perform even better in terms of durability, especially under high humidity conditions, which provides a potential solution to improve the durability of PEMFC stacks operating in harsh conditions. © 2024, The Authors. All rights reserved.

关键词： Durability

Selectivity catalytic reduction of NO by CO over Fe-Cu oxides supported on rice hull Ash(Rha) 7

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Selectivity catalytic reduction of NO by CO over Fe-Cu oxide...

7th International Conference on power engineering, ICOPE 2019

作者： Teng, Zhaohui Fu, Liang Li, Na Zhou, Qulan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xian710049 China

The present work contains the studies of catalytic reduction of NO with CO over 20 wt.% bimetallic Fe-Cu transition metal oxides supported on rice hull ash (RHA) and γ-Al2O3, which were prepared by various procedures. All catalysts contained CuO and Fe2O3 alongside with CuFe2O4. The catalytic activity kinetics for NO and CO reduction reaction mechanism was obviously improved over the synthesized RHA when compared to alumina support. And bimetallic metal catalyst Fe2Cu1/RHA demonstrated a high conversion of NO at all the temperatures examined. This was due to the strong interaction of Cu-Fe with the amorphous silica and activated carbon in RHA and high dispersion on the supporter. NO was almost reacted to N2 over Fe2Cu1/RHA from room temperature to 500℃ and O2 has little influence on it in our experiment conditions. About 100% CO was oxidized after 150℃ over Fe2Cu1/RHA. All the materials showed an unchanged stability over the period of 20h. Metallic copper and iron were the active species. The present results suggest that bimetallic Fe-Cu transition metal oxides supported on rice hull ash (RHA) can be used as an applicable catalyst to selectively reduce NO and CO. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Reduction

Studies on high temperature corrosion behavior of water wall materials under cyclic temperature 7

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Studies on high temperature corrosion behavior of water wall...

7th International Conference on power engineering, ICOPE 2019

作者： Liu, Zhuhan Wu, Zhengyu Li, Na Zhou, Qulan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

In this study, the corrosion behavior of water wall materials under cyclic temperature was studied. Corrosion products (XRD and EDS), corrosion morphology (SEM detection) and corrosion effects on residual matrix metal (SEM detection) were compared after different corrosion times to obtain the corrosion behavior under cyclic temperature conditions. There is no significant difference between the corrosion products of the sample at the circulating temperature and the corrosion products at the constant temperature. The corrosion surface layer is iron oxide, but according to the cross-sectional morphology it can be clearly observed that under the cyclic temperature condition, there is a certain increase in the corrosion layer thickness and the corrosion scales is broken with less protection. As the composition of T23, Cr didn't participate in the corrosion reactions to form a protective Cr2O3 protective layer, which is different in other materials. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： High temperature corrosion