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Dynamic modeling and behavior of parabolic trough concentrated solar power system under cloudy conditions

ENERGY 2019年 177卷 106-120页

作者： Wang, Anming Liu, Jiping Liu, Ming Li, Gen Yan, Junjie Xi An Jiao Tong Univ MOE Key Lab Thermal Fluid Sci & Engn Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

As a promising application of solar energy, parabolic trough concentrating solar power with indirect thermal energy storage has been widely used in concentrating solar power plants constructed in China. The dynamic modeling and behavior of the power plants were important for achieving fast start-up and shut down and to overcome weather disturbances. This study investigated the dynamic characteristics of a 50 MW parabolic trough concentrating solar power plant with indirect thermal energy storage. Simplified cloud disturbances were simulated to obtain the dynamic characteristics of a power block coupled with solar field and thermal energy storage. Simulation results indicated that the thermal inertia of solar field is an order of magnitude larger than that of power block and thermal energy storage subsystems, and the heat transfer fluid temperature at the solar field outlet fluctuates within a narrow range at rated value under the control scheme of solar field. The disturbances caused by heat transfer fluid temperature fluctuation were reduced by thermal energy storage operation. To minimize the generation load fluctuation under thick-cloud condition, the thermal energy stored in solar field could be used to moderate the fluctuation caused by the start-up of thermal energy storage discharging exchanger. (C) 2019 Published by Elsevier Ltd.

关键词： Parabolic trough concentrating solar power Clouds disturbances Second-scale dynamic modeling Dynamic behaviors

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Computational fluid dynamics investigation on the effect of co-firing semi-coke and bituminous coal in a 300MW tangentially fired boiler

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART A-JOURNAL OF power AND ENERGY 2019年第2期233卷 221-231页

作者： Du, Yongbo Wang, Chang'an Wang, Pengqian Meng, Yi Wang, Zhichao Yao, Wei Che, Defu Xi An Jiao Tong Univ Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Xian Thermal Power Res Inst Co Ltd Xian Shaanxi Peoples R China

In this paper, the effect of co-firing semi-coke in a 300MW tangentially fired boiler was numerically investigated. The results indicate that the incomplete combustion heat loss and NOx emission both increase with semi-coke co-fired ratio. Semi-coke may be injected into the furnace at a different height, which can lead to different thermal efficiency and NOx emission. It is suggested that semi-coke should not be fed from the top or bottom layer burners, since this could give rise to high carbon content respectively in fly ash and bottom slag. In addition, injecting semi-coke from the top burners could significantly increase the NOx emission. Under 1/2 co-firing ratio, the optimal fuel allocation is that feeding semi-coke from the B, D, and E layer burners. The growth in semi-coke particle size could increase the unburned carbon loss and NOx emission. It is highly recommended to reduce the unburned carbon loss under semi-coke co-fired condition by increasing the stoichiometric ratio of primary air for semi-coke. As it is increased from 0.25 to 0.3, the combustion efficiency of the co-fired condition is 99.47%, the same as when only firing bituminous coal, and the NOx emission is about 30% higher.

关键词： Pulverized boiler semi-coke co-firing NOx emission computational fluid dynamics

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Non-equilibrium spontaneous condensation flow in cryogenic turbo-expander based on mean streamline off-design method

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CRYOGENICS 2019年 98卷 18-28页

作者： Niu, Lu Chen, Xingya Sun, Wan Chen, Shuangtao Hou, Yu Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Chongqing Univ Key Lab Low Grade Energy Utilizat Technol & Syst Chongqing 400044 Peoples R China

In a modem cryogenic liquefaction system, the turbo-expander is used to operate in the two-phase region so that a high cooling capacity can be provided. Compared with the expansion process in a conventional over-heated turbo-expander, non-equilibrium condensation occurs in the duct when the turbo-expander operates in the two-phase region, which varies the expansion process. In our previous works, the simulation by CFX can predict the nucleation process controlled by gaseous sub-cooling well, and the outlet liquid fraction has a good agreement with our experimental data. As the non-equilibrium condensation simulated by using CFX consumes much time and massive computing resource, it is not feasible to simulate the two-phase expansion in the turbo-expander in a wide off-design range. In this study, we investigate the non-equilibrium spontaneous condensation along the mean streamline of a cryogenic turbo-expander passage by using an off-design computational code compiled by Matlab. The two-phase off-design computational code is developed from our previous overheated off-design code. The calculation function of thermodynamic parameters on the mean streamline and non-equilibrium condensation module are integrated with this code. The variations of thermodynamic parameters on the mean streamline in a non-equilibrium condensation process are simulated. Nucleation onset, droplet growth/vaporization process, liquid fraction distribution are revealed. Droplet developing region is divided according to the droplet critical and mean radius. Simulation results of five two-phase cases are compared and analyzed, and different non-equilibrium condensation features and liquid fraction distributions are found. At last, isentropic efficiency and outlet liquid fraction are used to evaluate two-phase expansion performance, and it is found that the performance results from the simulation in five cases agree with experimental data well.

关键词： Cryogenic turbo-expander Two-phase off-design prediction Non-equilibrium condensation Liquid fraction Droplet growth

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Stability and activity of a co-precipitated Mg promoted Ni/Al2O3 catalyst for supercritical water gasification of biomass

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2019年第30期44卷 15842-15852页

作者： Li, Sha Guo, Liejin Nanjing Univ Sci & Technol Sch Energy & Power Engn Nanjing 210094 Jiangsu Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

We have investigated the stability and activity of a co-precipitated Mg promoted Ni/Al2O3 catalyst (Ni-Mg-Al) for supercritical water gasification (SCWG) of various biomass model compounds and real biomass. Phase stability and activity recovery of the Ni-Mg-Al catalyst were first compared with a catalyst prepared by impregnation method. It was found that the co-participated catalyst showed higher activity recoveries than the impregnated catalyst due to the stable Ni crystal size. Then, effects of SCWG variables including heating up rate, gasification temperature, catalyst loading amount and feedstock concentration, on the non-catalytic and catalytic gas yields and gasification efficiencies of glucose and phenol were evaluated. Results demonstrated that the presence of sufficient amount of Ni catalyst could realize complete carbon gasification of different organics, including phenol and real biomass. Catalyzed by Ni, CH4 was the more favored produced gas at 400-500 degrees C while H-2 yields were more abundant at 500-600 degrees C. Without catalyst, carbon gasification efficiencies of SCWG of different feedstock were in the order: glycerol > glucose > cellulose approximate to corncob approximate to poplar leaf approximate to sawdust > phenol, while those catalyzed by Ni were in the order: glycerol approximate to glucose approximate to cellulose approximate to phenol > corncob approximate to poplar leaf approximate to sawdust, illustrating that the co-precipitated Ni Mg Al catalyst is more active on catalyzing the gasification of water-soluble organics than real biomass. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Supercritical water gasification Nickel catalyst Hydrogen production Phenol Biomass

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Study on Dynamic Characteristics of a 600MW Ultra-Supercritical Double-Reheat Boiler 10

Study on Dynamic Characteristics of a 600MW Ultra-Supercriti...

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10th International Conference on Applied Energy (ICAE)

作者： Wang, Zhu Liu, Ming Wang, Chaoyang Chong, Daotong Yan, Yunjie Xi An Jiao Tong Univ Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian Shaanxi Peoples R China

Based on the GSE software, the simulation model of an ultra-supercritical double-reheat tower boiler was established, and its reliability was checked with design data. Then, the dynamic characteristics of the ultra-supercritical double-reheat boiler were studied. Simulation results reveal the response times of different input parameters greatly vary. When stepping disturbances to the feed-coal rate, feed-water rate, and feed-water temperature, the response time under feed-water's temperature disturbance is the longest, which is about 1, 800 s. When the same input parameter disturbs, the output parameters have the same response tendency with different amplitudes. Moreover, the fiercer the disturbance is, the more greatly the parameter changes. (C) 2019 The Authors. Published by Elsevier Ltd.

关键词： double-reheat dynamic characteristics GSE

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Automatic differentiation approach for solving one-dimensional flow and heat transfer problems

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ANNALS OF NUCLEAR ENERGY 2021年 160卷 108361-108361页

作者： Niu, Yuhang He, Yanan Xiang, Fengrui Zhang, Jing Wu, Yingwei Tian, Wenxi Su, Guanghui Qiu, Suizheng Xi An Jiao Tong Univ Sch Nucl Sci & Technol Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Shaanxi Key Lab Adv Nucl Energy & Technol Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

Traditional reactor system analysis tools are confronted with challenging difficulties in model development, low accuracy, and poor convergence. To solve these problems, the automatic differentiation (AD) method that allows the automatic numerical calculation of derivatives of functions was adopted to develop the reactor system code in this paper. For the simulation of single-phase models, the steady and transient responses were presented to investigate the effects of the spatial and temporal discretization schemes on modeling accuracy and efficiency. Meanwhile, the comparison of convergence performance between the automatic differentiation using operator overloading (ADOO) and the traditional hand-coded method was completed. Further, in the case of two-phase flow problems, the high-order discrete schemes were applied in this code. It was demonstrated that the reactor system code with single-phase and five-equation two-phase flow models, which adopted the high-order discretization and the ADOO method, performed very well for one-dimensional flow and heat transfer problems. (C) 2021 Published by Elsevier Ltd.

关键词： Automatic differentiation Single-phase and two-phase flow High-order discretization flow and heat transfer

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Autogenous growth of the hierarchical V-doped NiFe layer double metal hydroxide electrodes for an enhanced overall water splitting

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DALTON TRANSACTIONS 2020年第32期49卷 11217-11225页

作者： Liang, Jin Shen, Haiqi Ma, Yaming Liu, Dongyu Li, Mingtao Kong, Jie Tang, Yusheng Ding, Shujiang Northwestern Polytech Univ MOE Key Lab Space Appl Phys & Chem Shaanxi Key Lab Macromol Sci & Technol Sch Chem & Chem Engn Xian 710072 Peoples R China Xi An Jiao Tong Univ Dept Appl Chem Sch Sci Xian Key Lab Sustainable Energy Mat Chem Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Int Res Ctr Renewable Energy Xian 710049 Peoples R China Xi An Jiao Tong Univ Shenzhen Acad Shenzhen 518057 Peoples R China

NiFe layer double metal hydroxide nanosheets (NiFe LDHs) have been extensively investigated as one of the best promising candidates to construct efficient bifunctional catalysts. In this research, element (vanadium) doping into NiFe LDHs grown in nickel foam were synthesized by the one-step method and applied in overall water splitting. The content and structure of the composites were adjusted to regulate the catalyst's electronic structure and reduce the onset potential and achieved unprecedented electrocatalysis for OER and HER. The V-NiFe-LDH/NF showed perfect OER and HER activities with low Tafel slopes of 31.3 and 89.8 mV dec(-1), and small overpotentials of 195 and 120 mV at 10 mA cm(-2) in 1.0 m KOH solution, respectively. Electrochemical analysis indicated that the efficient catalytic activity of V-NiFe-LDHs/NF mainly benefited from V doping, which optimized the electronic structure and produce defects, thereby resulting in an enhanced conductivity, facile electron transfer, and adequate active sites.

关键词： Iron alloys

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Experiments and Simulation on Co-Combustion of Semicoke and Coal in a Full-Scale Tangentially Fired Utility Boiler

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ENERGY & FUELS 2019年第4期33卷 3012-3027页

作者： Wang, Pengqian Wang, Chang'an Du, Yongbo Feng, Qinqin Wang, Zhichao Yao, Wei Liu, Jiali Zhang, Jinping Che, Defu Xi An Jiao Tong Univ Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Xian Thermal Power Res Inst Co LTD Xian 710054 Shaanxi Peoples R China

Co-firing semicoke and coal in utility boilers is a promising approach to cleanly and efficiently utilize semicoke, while the co-combustion characteristics have yet to be fully understood, including the effects of the blending method and secondary air distribution mode on NOx emission and combustion efficiency. In the present work, both full-scale experiments and simulation were carried out to investigate the co-combustion characteristics of semicoke and coal in a 300 MW coal-fired utility boiler with a focus on the blending method and air distribution. The results indicated that co-firing semicoke would reduce the furnace temperature and that both NOx emission and incomplete combustion heat loss increased with the blending amount of semicoke. Hence, to limit the excessive deterioration of boiler performance, the blending amount of semicoke was recommended to be below 50% for the in-furnace blending method and below 33% for the out-furnace blending method. When the in-furnace blending method was employed, the semicoke and coal were recommended to be fed from burners in alternate layers, in particular, without semicoke fed from the top and/or bottom burners. The NOx emission was proved to positively correlate with the average height of semicoke burners, while the burnout ratio increased at first and then decreased with the increasing average height. The in-furnace blending method with optimal burner allocation was proved to have advantage over the out-furnace blending method. The secondary air distribution of the pagoda down type could reduce NOx generation and unburned carbon due to the formation of a high-temperature and strong reducing atmosphere within the furnace.

关键词： Redox reactions Atmospheric chemistry Layers Coal Fuels

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Remote open-path laser-induced breakdown spectroscopy for the analysis of manganese in steel samples at high temperature

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Plasma Science and Technology 2019年第3期21卷 52-59页

作者： Minchao CUI Yoshihiro DEGUCHI Zhenzhen WANG Seiya TANAKA Min-Gyu JEON Yuki FUJITA Shengdun ZHAO School of Mechanical Engineering Xi'an Jiaotong University Graduate School of Advanced Technology and Science University of Tokushima State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Division of Mechanical Engineering Korea Maritime and Ocean University School of Mechanical Engineering Xi’an Jiaotong University

A remote open-path laser-induced breakdown spectroscopy(LIBS) system was designed and studied in the present work for the purpose of combining the LIBS technique with the steel production line. In this system, the relatively simple configuration and optics were employed to measure the steel samples at a remote distance and a hot sample temperature. The system has obtained a robustness for the deviation of the sample position because of the open-path and alloptical structure. The measurement was carried out at different sample temperatures by placing the samples in a muffle furnace with a window in the front door. The results show that the intensity of the spectral lines increased as the sample temperature increased. The influence of the sample temperature on the quantitative analysis of manganese in the steel samples was investigated by measuring ten standard steel samples at different temperatures. Three samples were selected as the test sample for the simulation measurement. The results show that, at the sample temperature of 500 ℃, the average relative error of prediction is 3.1% and the average relative standard deviation is 7.7%, respectively.

关键词： remote open-path LIBS steel manganese sample temperature quantitative analysis

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Energy allocation optimization of the gas-cooled space nuclear reactor

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APPLIED THERMAL engineering 2021年 196卷 117289-117289页

作者： Qin, Hao Wang, Chenglong Tian, Wenxi Qiu, Suizheng Su, Guanghui Xi An Jiao Tong Univ Dept Nucl Sci & Technol Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Shaanxi Key Lab Adv Nucl Energy & Technol Xian Jiaotong Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian Jiaotong Peoples R China

The development of the space vehicles puts forward higher requirements on the energy supply, and the megawatt gas-cooled space nuclear reactors are promising to satisfy the demand. The energy allocation optimization on the space nuclear reactors takes critical part in the system design. The optimization between the energy conversion efficiency and radiator mass of the gas-cooled space nuclear reactor is conducted and analyzed. The models of direct Brayton cycle, heat pipe radiator, and liquid droplet radiator are established. The working performance of the thermodynamic cycle coupled with heat pipe radiator (HPR) and liquid droplet radiator (LDR) are obtained respectively, and compared. The area and weight of the HPR increases linearly with the radiant power. The calculation results show that, for space nuclear reactors adopting HPR, decreasing the coolant temperature at the reactor core outlet (T-1) from 1500 K to 1200 K will increase the specific surface area from 1200 m(2)/MW to about 3000 m(2)/MW with the same energy conversion efficiency. The radiant power of the LDR can be regulated by operation mode with the radiator weight remains unchanged. The mass of LDR is only about 10% of HPR for case with electricity power P-e = 0.5 MW, T-1 = 1500 K, showing significant advantage in the mass optimization. This paper may contribute to the energy management and allocation optimization of the gas-cooled space nuclear reactor.

关键词： Gas-cooled space nuclear reactor Heat pipe radiator Liquid droplet radiator direct Brayton cycle Energy allocation optimization

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