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SSRN 2022年

作者： Zhang, Meng Xu, Wanying Wang, Ruixiang Wei, Xutao Wang, Jinhua Huang, Zuohua Tan, Houzhang State Key Laboratory of Multiphase Flow in Power Engineering Xian Jiaotong University Xian710049 China MOE Key Laboratory of Thermo-Fluid Science and Engineering Xian Jiaotong University Xian710049 China

Ammonia (NH 3 ) combustion is regarded as one of the most promising solutions to realize zero CO 2 emission. However, the low reactivity, low heat release result in a strong flame-wall interaction (FWI) which significantly affects the flame stabilization and the NOx emission characteristics. In this study, an air film cooling on the swirling combustion chamber was designed to investigate the thermal effect of the FWI on NOx emission. The flame structure and NO production are measured with the OH-/NO-PLIF techniques. The NOx emission is analyzed by the Gasmet DX4000 Fourier Transform Infrared (FTIR) gas analyzer. Large eddy simulation is also conducted to extend the understandings of experimental findings. For the current combustion chamber, the temperature difference is increasing as downstream location, resulting a larger convection heat loss. The heat loss shows no apparent effect on the flame structure and NO production at the symmetrical plane. The flame tends to be more fragmentized and the NO production is largely decreased at near wall region and the outer recirculation zone with increasing heat loss. This can be understood that NO production rate from the oxidation of NH i by O, H and OH radicals through HNO is largely decreasing in these regions. Therefore, a decreasing NO trend is found at the chamber outlet. NO emission shows a decreasing trend with heat loss at lean condition, which is mainly caused by the decreased NO production at near wall region resulting from the lower combustion efficiency. However, N 2 O, a more serious greenhouse gas, significantly increases as the heat loss increases. This is mainly because that the production of N 2 O from NO is promoted and N 2 O decomposition is suppressed within the thermal boundary. Thus, N 2 O might become a more serious emission component in NH 3 fuelled gas turbines. Moreover, a tradeoff behaviour between NO and N 2 O is observed as increasing heat loss. This study suggests the thermal effect of FWI on t

关键词： Heat losses

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Catalytic Gasification of Large Particle Size Biomass with Loaded Aaems Under Oxygen-Steam Atmosphere

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SSRN 2023年

作者： Ren, Jiyun Yang, Kaixuan Li, Yuhang Bai, Yang Jiang, Jiahao Huang, Xiaole Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Shanghai Power Equipment Research Institute Co. Ltd. Shanghai200240 China Xi’an Thermal Power Research Institue Co. Ltd. Xi’an710032 China

To evaluate the effect of alkali and alkaline earth metals species (AAEMs) on the catalytic gasification of large particle size biomass, a vertical fixed-bed reactor is conducted for candlenut wood gasification under the oxygen-stream atmosphere. The gasification chars derived from gasification are characterized by SEM, X-ray CT, BET, and FTIR. Tar and syngas are analyzed via GC-MS and GC respectively. Advanced X-ray CT technology provides beneficial visualization to assist in the interpretation of the catalytic gasification of large particle size biomass loaded with AAEMs. The results indicate a progressive augmentation of AAEMs content along the radial direction and end surface for all loaded samples and gasification chars, which could also be visualized from the 3D reconstruction of X-ray CT. Many large pores (40-60 μm) aligned along the grain direction collapse after gasified and generate numerous micropores in gasification chars. 10-20 μm pores are more prominent in chars loaded with KCl and CaCl2. The char loaded with CaCl2 has more well-developed pores, a larger specific surface area, and -OH compounds, aldehydes, ketones and carboxylic acids. The addition of AAEMs facilitates the high generation of M1 compounds (contains 1 benzene ring) in the tar and suppresses the enhancement of other compounds, M4 compounds, and long-chain alkanes. H2 and CO concentrations augments and declines by loading AAEMs. The highest H2 concentration of 62.1% is detected by the addition of CaCl2. When loaded with KCl, the syngas calorific value reduces by 1.37%, while loaded with NaCl, CaCl2, and MgCl2 show an augmentation of 11.48%, 10.56%, and 2.55%, respectively. A decrement of CnHx concentration in syngas derived from samples loaded with KCl and MgCl2 and an increment one loaded with NaCl and CaCl2 are acquired. © 2023, The Authors. All rights reserved.

关键词： Oxygen

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Dynamic simulation of coal-fired power plant integrated with trough solar collector operating in parallel with high pressure heaters

Dynamic simulation of coal-fired power plant integrated with...

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2019 Canadian Society for Civil engineering Annual Conference, CSCE 2019

作者： Yan, Hui Li, Xin Liu, Ming Chong, Daotong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9780791883747

Solar-aided coal-fired power plant (SACFPP) is a costeffective approach to overcome solar energy intermittency. SACFPPs frequently operate in dynamic processes due to power load and solar energy fluctuations. This study investigated the dynamic characteristics of SACFPPs;such characteristics are important for flexibility evaluation and control system design. The SACFPP used in this study was based on a 660 MW coalfired power plant, and a trough collector system (TCS) operates in parallel with high pressure (HP) heaters. After model development and validation, the dynamic performance of the SACFPP was analyzed under four load ratios of power plant, with disturbances of two parameters: direct normal irradiance (DNI) and mass flowrate ratio to TCS. The performance was also compared with three parallel TCS connection modes. Results showed that the magnitude and response time for power variation under DNI disturbance increased with load ratio. With 500 W/m2 DNI step increments, power increased by approximately 18.4, 21.2, 24.7, and 29.8 MW in 2200, 2330, 2550 and 2620 s at 70%, 80%, 90%, and 100% load ratios, respectively, when all the HP heaters were replaced. The serial number and the number of HP heaters replaced also increased the power variation and response time. Under mass flowrate ratio to TCS increase disturbance, the power rapidly changed to its maximum and then slowly decreased, but the variation value depended on the load ratio. Copyright © 2020 ASME.

关键词： Coal fired power plant

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Characteristics of Bubble Dynamic Behavior on the Surface of Photoelectrode Under the Influence of a Vertical Magnetic Field

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SSRN 2023年

作者： Feng, Yuyang Wang, Yechun Zhang, Bo Cao, Zhenshan Liu, Miaomiao Zhen, Canghao Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Xinjin Weihua Institute of Clean Energy Research Nanhai District Guangdong Province Foshan City China

The magnetohydrodynamic (MHD) flow around the bubble induced by the Lorentz force owing to the applied magnetic field significantly affects the behavioral characteristics of the bubble on the electrode surface. However, the mechanism of the impact of a magnetic field perpendicular to the electrode on the dynamic behavior of bubbles remains unclear. In this study, the evolution law of a single oxygen bubble on the surface of a TiO2 photoelectrode under the influence of a vertical magnetic field with different magnetic induction intensities was investigated. The vertical magnetic field effectively promoted the rapid detachment of bubbles from the electrode surface, and greatly improved the gas evolution efficiency. The mass transfer was dominated by single-phase free convection during bubble evolution. Under the influence of the vertical magnetic field, the mass transfer coefficient near the electrode was enhanced, and the adverse effects of bubbles on mass transfer were counteracted when they entered the reaction-controlled growth phase. The further multiphysics simulation found that the MHD convection decreased the local supersaturation of reaction product oxygen molecules near the electrode, thereby reducing concentration overpotential and increasing the reaction rate. This study provides an experimental and theoretical basis for promoting the bubble detachment and the reaction rate on the gas evolving electrode surface during photoelectrochemical water splitting. © 2023, The Authors. All rights reserved.

关键词： Efficiency

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Multi-Objective Optimization and Configurations Comparison of Closed-Air Brayton Cycle

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SSRN 2023年

作者： Qian, Yiran Gu, Zhenzhen Song, Meihui Yang, Yi Zhao, Quanbin Chen, Weixiong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China China Institute of Atomic Energy P.O. Box 275-32 Beijing102413 China

Microreactor power system has characteristics of efficient, compact and high environmental adaptability. In this study, closed-air Brayton cycle (CABC) is proposed as the microreactor thermoelectric conversion system, and thermodynamic model of CABC with different configurations are established. The cycle parameters and component’s structure are designed using system-component combined design method. To obtained the optimal system design scheme, the Genetic Algorithm (GA) and the Non-dominated Sorting Genetic Algorithm II (NSGA-II) are separately applied for single-objective optimization and multi-objective optimization. According to multi-objective optimization results, the IRRC has the highest cycle efficiency of 35.4% and the ratio of power to mass of 59.1 kW·t-1 , respectively, and the RRC has the highest power density of 179.6 kW·m-3 . Similar performance with IRRC and simpler structure make the RRC the optimal configuration of CABC. Compared with single-objective optimization, the design results of multi-objective optimization are more balanced in terms of three performance indicators, meaning that the optimized design scheme has a better comprehensive performance. © 2023, The Authors. All rights reserved.

关键词： Multiobjective optimization

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Low-energy and accelerated hydrogen release from MgH2–5 wt% NaTiOxH catalyzed hydrogen storage reactor by graphite responsive microwave

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Journal of Magnesium and Alloys 2025年

作者： Wang, Bofei Wu, Zhen Liu, Honghao Yang, Fusheng Zhang, Zaoxiao Yao, Jing Li, Qian Cao, Hujun Li, Bo State Key Laboratory of Fluorine & Nitrogen Chemicals School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow for Power Engineering Xi'an Jiaotong University Xi'an710049 China National Engineering Research Center for Magnesium Alloys Chongqing University Chongqing400044 China Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian116023 China Faculty of Engineering Electrical Energy Management Group University of Bristol BristolBS8 1QU United Kingdom

Owing to high thermal stability and large reaction enthalpy, MgH2 has high reaction temperatures and sluggish reaction kinetics in the dehydrogenation process, which consumes lots of energy. To achieve hydrogen release with low energy consumption, accelerated reaction rate, and high heating uniformity, this paper proposes a novel method of graphite responsive microwave-assisted thermal management with NaTiOxH catalyst. A multi-physics model of the 5 wt% NaTiOxH catalyzed MgH2 reactor integrated with a microwave generator is developed to investigate the reaction, heat and mass transfer process of hydrogen release. It is found that the graphite responsive microwave heating method could improve the temperature uniformity of reaction bed, reduce the energy consumption by at least 10.71% and save the hydrogen release time by 53.49% compared with the traditional electric heating method. Moreover, the hydrogen desorption thermodynamics could be improved with the increase of microwave power. The hydrogen release time is shortened by 19.55% with the increase of 20 W microwave power. Meanwhile, it is also concluded that the microwave excitation frequency of 2.1 GHz and the graphite content of 2 wt% have better heating performance. Therefore, it can be verified that the graphite responsive microwave heating helps to low-energy and accelerated hydrogen release from MgH2 hydrogen storage reactor. © 2025

关键词： Reaction rates

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Numerical Study on Transverse Mixing Characteristics of flow Sweeping in Helical Cruciform Rod Bundle

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SSRN 2022年

作者： Jiang, Dianqiang Zhang, Dalin Tian, Wenxi Qiu, Suizheng Su, Gguanhui 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

In the chemical industry, nuclear energy, electronics, and other industries, heat transfer enhancement has been the focus of significant attention. To enhance the flow heat transfer performance of coolant in the nuclear fuel assembly, helical cruciform fuel rods are designed as a foundation fuel element. The transverse mixing characteristics of flow sweeping of heat conduction oil in the present study using the numerical approach in helical cruciform rod bundle. The fluid in the helical cruciform rod bundle exhibits a substantial flow sweeping crossflow phenomena as a result of the impact of the helical structure. The transverse mixing velocity and temperature profiles are analyzed. The subchannel conservation equation is optimized, and the link between flow sweeping mixing parameters and dimensionless local gap width in various Reynolds number ranges is determined by fitting. Furthermore, the turbulent mixing parameters of the cylindrical rod bundle are analyzed. It can be concluded that the helical cruciform rod bundle has considerable transverse mixing, which enhances the flow heat transfer performance of the reactor core. This study provides a guide for the numerical study of flow heat transfer in helical structures, and a foundation for the development of the subchannel mixing model. © 2022, The Authors. All rights reserved.

关键词： Mixing

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Transferring the available fused cyclic scaffolds for high—throughput combinatorial design of highly energetic materials via database mining

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Fuel 2022年第PartA期324卷

作者： Wen, Linyuan Yu, Tao Lai, Weipeng Liu, Maochang Wang, Bozhou Shi, Jinwen Liu, Yingzhe State Key Laboratory of Fluorine & Nitrogen Chemicals Xi'an Modern Chemistry Research Institute Xi'an710065 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Recently, the fused cyclic compounds have been the object of an increased interest in the field of energetic materials (EMs) due to the trade-off between energy and safety. Compared with the fused cyclic EMs consisting of the azoles or azines, the oxazole-based fused EMs which possibly possess higher energy–density are very lacking. Here, we proposed an efficient approach to design the highly energetic oxazole-based fused materials. The domain-related knowledge promoted an advanced database search for the aromatic oxazole-based scaffolds from the buyable subset of the ZINC20 database, ensuring scaffolds are available for purchase. Then, 171 target scaffolds were transferred into the EM field and cooperated with combinatorial design to construct a chemical space containing over 107 potential energetic molecules. The high-throughput screening was performed in four aspects, namely, density, difficulty of synthesis, detonation performance, and sensitivity, to accelerate the search for candidates. Meanwhile, the statistical analysis through the hierarchical filtrations clarified the potential of 2r-3s and 2r-4s scaffold types for creating highly energetic molecules. Finally, several candidates stood out owing to nearly 10000 m/s detonation velocity and acceptable predicted sensitivity, elucidating the effectiveness of our approach. We anticipate this investigation could not only be a vital point for subsequent fused cyclic EM research, but also offered a new avenue for material design in other fields. © 2022 Elsevier Ltd

关键词： Scaffolds

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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

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Neutronic/Thermal-Hydraulic Coupling Analysis of Heat Pipe Reactor Nuster-100 Based on Comsol

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SSRN 2022年

作者： Zhang, Yin Nie, Jingyu Wang, Chenglong Guo, Kailun Tian, Wenxi Su, Guanghui Qiu, Suizheng 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 nuclear reactor plays an important role in future space and ocean exploration missions due to its advantages such as high inherent safety, removability, passive safety. Xi’an Jiatong University proposed a concept design of 100kWe nuclear reactor named NUclear Silent ThermoElectric heat pipe cooled Reactor (NUSTER-100). To explore NUSTER core’s performances, COMSOL are used for neutronic/thermal-hydraulic coupling calculation. Neutron diffusion equations are used to calculate NUSTER’s neutron flux distribution by partial differential equation (PDE) model. Dragon code is used to solve the group constants of neutron diffusion equations. The heat transfer module of COMSOL is used to calculate NUSTER’s temperature distribution. for NUSTER-100, the keff calculated by the neutron diffusion module of COMSOL is 1.0372. The calculation results of three-dimensional NUSTER show that the maximum temperature of heat pipe is 1226.2 K and that of fuel rod is 1447.1K. The calculated temperatures have not exceeded the limit. The unified calculation of neutron physics and temperature distribution is realized in COMSOL platform. This work provides a preliminary basis for neutronic/thermal-hydraulic coupling calculation for heat pipe reactor. © 2022, The Authors. All rights reserved.

关键词： Heat pipes

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