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Comprehensive Performance Analysis of Steam and Flue Gas Stepwise/Staged Heating Molten Salt Thermal Storage Systems Coupled with Coal-Fired power Plants

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SSRN 2024年

作者： Jing, Hao Wang, Dengliang Chen, Weixiong Zhao, Yongliang Wang, Chaoyang Zhang, Kezhen Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Xi’an Thermal Power Research Institute Co. Ltd. Xi’an710054 China

The rapid development of renewable energy has put forward higher requirements for the flexibility and deep peak shaving ability of coal-fired power plants (CFPPs). Molten salt thermal energy storage (TES) is considered a potential solution. In this study, a CFPP coupled steam and flue gas stepwise/staged heating molten salt TES system is proposed. The proportion of steam thermal energy allocated to the molten salt and feed water is adjusted. The thermodynamic and economic performance of two configurations under different thermal load distribution ratios are compared and studied. The results show that with the increase of molten salt thermal load distribution ratio, the thermal storage capacity, denitrification efficiency, and charging exergy loss increase, while the equivalent round-trip efficiency, energy storage density, and discharging exergy loss decrease. When the molten salt thermal load distribution ratio is the same, the stepwise configuration has higher energy storage density and denitrification efficiency, lower charging exergy loss of TES, and better economic performance. The staged configuration has higher thermal storage capacity and lower exergy loss of CFPP. In general, the economic performance of the stepwise configuration is higher, while the staged configuration's thermodynamic performance is higher. © 2024, The Authors. All rights reserved.

关键词： Coal fired power plant

An Investigation on the Formation and flow Characteristics of Nature Gas Hydrates at Different Loop Inclination Angles

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SSRN 2022年

作者： Liu, Ni Wang, Cheng Meng, Fei Yang, Liang Liu, Daoping School of Energy and Power Engineering The University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China

One of the major issues in flow assurance includes pipeline plugging due to gas hydrate formation and deposition,which makes it imperative to look for appropriate hydrate control strategies. In this study, a high-pressure visual flow loop was used to analyze the influence of different inclination angles (0°–4°) on the formation, flow, morphology evolution, deposition process, and mechanism of hydrates. The macro-parametric data, including pressure, temperature, velocity, hydrate induction time and hydrate volume fraction, were compared and analyzed. Results showed that the hydration reaction rate of downslope section is slightly faster than that of upslope section in inclined section. Although the amount of hydrate finally formed is the same, the hydrate in the downslope section is more dense. While the loop inclination angle had little effect on the amount of hydrate formation, with the increase of inclination angle, the induction time tends to decrease and the hydration reaction time will be longer overall. At 1° inclination angle, the induction time was the shortest and the hydration reaction time was the longest. The deposition process of the horizontal pipe is divided into four stages, in which large hydrate particles in the liquid phase are evenly distributed throughout the pipeline, forming a hydrate moving bed. The hydrate deposition process of the inclined pipe is also divided into four stages. Among them, the large hydrate particles in the liquid phase are concentrated on the upper wall of the pipeline, which causes the density of the upper part of the pipeline to be much higher than that of the lower part, forming a hydrate-fixed *** results of this study can deliver theoretical support to ensure the safe transportation of gas hydrate slurries. © 2022, The Authors. All rights reserved.

关键词： Gas hydrates

Study on the Aerodynamic Characteristics of Vertical Axis Wind Turbines Based on Omnidirectional Guide Grids

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SSRN 2023年

作者： Zhou, Ye Xiandong, Li Hao, Yu Renhao, Ruan School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China

In order to analyze the influence of the structural parameters of the omnidirectional deflector on the aerodynamic performance of the vertical axis wind turbine, a combination of the inclination angle, relative distance, and thickness of the blade grid was designed to compare the influence of the structural parameters of the omnidirectional deflector on the aerodynamic performance of the vertical axis wind turbine under various tip speed ratio conditions. The results show that the wind power utilization rate and moment coefficient of the wind turbine under the effect of the omnidirectional deflector grille tend to increase and then decrease as the inclination angle increases, and the best effect on the wind turbine aerodynamic performance is achieved when the inclination angle is 0°, the wind turbine moment is greatly increased, and the range of effective operating conditions is expanded. When the inclination angle is 0° at all relative distances, the omnidirectional deflector grid can improve the pressure distribution of wind turbine blades, and the corresponding pneumatic performance improvement increases with the relative distance. When the relative distance is 2.6, the best effect on the wind turbine's aerodynamic performance is achieved. By changing the number of deflector blades and chord length to adjust the grid consistency, the vertical axis wind turbine aerodynamic performance curve under the action of the omnidirectional deflector shifts toward the direction of the large tip speed ratio as the grid consistency increases, and the corresponding wind energy utilization rate and torque coefficient peak are increasing and then decreasing when the chord length is 374mm (grid consistency is 0.267). When the chord length is 374mm (the blade thickness is 0.267), the best effect on the aerodynamic performance of the vertical axis wind turbine is achieved. © 2023, The Authors. All rights reserved.

关键词： Vertical axis wind turbine

The formation of droplet encapsulating particles in a Y-typed microchannel

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Measurement: Sensors 2021年 14卷

作者： Wang, Qing Liu, Qi Fan, Liang-Liang Zhao, Liang School of Mechanical Engineering Xi'an Jiaotong University Xi'an China School of Food Equipment Engineering and Science Xi'an Jiaotong University Xi'an China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

Droplet encapsulating particles has great potentials in microfluidic measurement and detection in many fields, such as biomedicine and food science. It is of great importance to investigate the formation of droplet encapsulating particles in microchannel. In this paper, considering the influence of channel angle, particle size, and volume fraction, VOF model and DPM model are combined to systematically study the formation of droplet containing particles in a Y-typed microchannel. The simulation results show that the particle size and concentration significantly influence the formation of droplet. In addition, in comparison with the formation of simple droplet, the angle of Y-typed microchannel and particles have synergistic effect on the droplet formation. The present work is of help for the precise control on the formation of droplet encapsulating particles, which is highly required for the following measurement and detection. © 2021 The Author(s)

关键词： Microchannels

EXPERIMENTAL INVESTIGATION ON THE REFLOODING IN A 5×5 ROD BUNDLE 29

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EXPERIMENTAL INVESTIGATION ON THE REFLOODING IN A 5×5 ROD B...

2022 29th International Conference on Nuclear engineering, ICONE 2022

作者： Liu, Weihua Yuan, Hongsheng Wu, Pan Wang, Ting Shan, Jianqiang School of Nuclear Science and Technology Xi'an Jiaotong University No. 28 Xianning West Road Shaanxi Xi'an China China Nuclear Power Technology Research Institute Co. Ltd No.1001 Shangbu Middle Road Futian District Guangdong Shenzhen518026 China The State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an China

ISBN: (纸本)9780791886410

In the current study, a series of reflood tests with uniformly power input have been carried out at the 5×5 rod bundle film boiling test facility of the Nuclear Safety and Operation laboratory(NUSOL) of Xi'an Jiaotong University and the experimental results have been analyzed in detail. The effect of several parameters, including subcooling of coolant (10K to 75K), coolant flow rate (2.5m/s to 10.0m/s) and input wall linear power density (7 W/cm to 13 W/cm) on quench front of reflooding patterns have been studied. It is observed that the quench front during reflood stage of the rod bundle channel is sensitive to above parameters. Increase in input wall linear power density, and decrease in flow rate and subcooling of coolant results in delayed reflooding. The temperature, heat flux and heat transfer coefficient on the rod surface have been got via the self-development Reflooding Experimental Data Analysis (REDA) code. The data is not only useful for the development of theoretical models for film boiling heat transfer, two-phase void fraction, pressure drop, and rod bundle reflooding prediction, but also can be used as a benchmark data base for evaluating the analysis code of Loss of Coolant Accident (LOCA) in reactor and the design of the residual heat removal system. Copyright © 2022 by ASME.

关键词： Coolants

Simulation Study on the Dynamic Characteristics of Natural Circulation Coupled Phase Change Material for Equal Height Difference Passive Containment Cooling System

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SSRN 2024年

作者： Chen, Weixiong Huang, Yufan Wang, Han Yang, Xiaohu Li, Shaodan Zhao, Quanbin Chong, Daotong State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Wuhan Second Ship Design and Research Institute Wuhan430205 China

The passive containment cooling system (PCCS) plays a significant role in ensuring the safety of nuclear power plants. To further reduce peak pressure in the containment during a loss of coolant accident (LOCA), phase change materials (PCMs) are utilized to improve the system’s cooling effectiveness. The dynamic simulation model of PCCS has been developed using Apros software. This article focuses on examining the system’s dynamic characteristics related to various tube startup methods and comparatively analyzing the impact of different PCM thicknesses on heat transfer capacity. The results indicate that post-accident, PCM significantly suppresses peak pressure in the containment. Under the full tube startup method with 4 mm PCM, the peak pressure decreases to 1.75 MPa, whereas under the empty tube startup method, it is reduced to 1.69 MPa. With natural circulation empty tube startup method, PCM can reduce pressure change intensity in the containment but negatively affects natural circulation heat transfer. Although the full tube startup method underperforms the empty tube startup method on suppressing peak pressure, PCM can positively affect natural circulation heat transfer in the early stages of the accident. Empty tube startup offers the advantages of higher heat transfer capacity and lighter weight, making it the optimal choice for ocean nuclear platforms. Additionally, the higher peak power of PCM heat transfer under the empty tube startup method indicates that system can withstand larger thermal shocks. © 2024, The Authors. All rights reserved.

关键词： Thermoelectric equipment

Numerical Study on Phase-Change Thermal Storage for Thermal Management of Intermittent High-power Devices

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SSRN 2022年

作者： Chen, Liang Fan, Jing Zhang, Pingtao Xiao, Runfeng Si, Yansong Chen, Shuangtao Hou, Yu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Key Laboratory of Icing and Anti/De-Icing China Aerodynamics Research and Development Center Mianyang621000 China

Latent heat thermal energy storage (LHTES) is an effective approach for thermal management of intermittent high-power output electronics. The limited heat absorption power due to the low conductivity of phase change material is an urgent problem for LHTES. This paper investigates a finned tube heat exchanger with dual-side phase change heat transfer, i.e., LHTES of paraffin RT60 on the fin side and condensation of low-pressure water on the tube side. The proposed model couples the three-dimension enthalpy-porosity model on the fin side with the one-dimension homogeneous flow model on the tube side, yielding the solutions of the dynamic process of the LHTES. The heat-charging power and storage effectiveness of LHTES with single-phase and two-phase heat transfer fluids (HTFs) on the tube side are compared and discussed under different condensation pressures and mass flow rates. Heat transfer on both the fin and tube sides are critical for the LHTES performance, and the use of two-phase HTF on the tube side can enhance the heat-charging power by 210.5% and raise the storage effectiveness by 33.5%. The storage effectiveness decreases with the increase of condensation pressure while the mass flux of tube-side HTF does not have an obvious effect on the storage effectiveness. The maximum power density (1.3 kW/L) of LHTES is obtained when the condensing pressure is 90 kPa and the mass flow rate is 0.045 kg/s. It is indicated that dual-side phase change heat transfer to storage energy can provide a compact and efficient thermal management solution for intermittent high-power devices. © 2022, The Authors. All rights reserved.

关键词： Temperature control

Boosting photocatalytic water vapor splitting by the integration of porous g-C_(3)N_(4)and carbonized melamine foam

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Science China Materials 2024年第9期67卷 2957-2964页

作者： Shujian Wang Dongjie Liu Chunyang Zhang Jie Huang Shidong Zhao Kejian Lu Biao Wang Hao Peng Yitao Si Maochang Liu International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an710049China School of Chemistry and Chemical Engineering Southeast UniversityNanjing211189China Suzhou Academy of Xi’an Jiaotong University Suzhou215123China Gree Altairnano New Energy Inc. Zhuhai519040China

We report a photothermally-induced liquid-solid/gas-solid-decoupling photocatalytic water-splitting system,where a carbonized melamine foam(CMF)and a porous g-C_(3)N_(4)(PCN)serve as the photothermal substrate and model photocatalyst,***,liquid water is transformed into the gaseous phase over the CMF due to the photothermal effect,and the generated vapor can be split into hydrogen by PCN via the *** unique biphasic photocatalytic system exhibits a high hydrogen production rate of 368.1µmol h^(-1),which is 2.4 and 25.6 times larger than those of the traditional triphasic PCN system(151.7µmol h^(-1))and g-C_(3)N_(4)(CN)system(14.4µmol h^(-1)),*** improved photocatalytic performance is mainly attributed to the optimized energy and mass transfer at the gas-liquid-solid reaction interface,where gas products are rapidly desorbed in the photocatalytic *** work provides a novel strategy to enhance the photocatalytic performance from the perspectives of energy and mass flow.

关键词： photocatalytic photothermal mass transfer g-C_(3)N_(4) gas-solid

Numerical Study on the Local Heat Transfer Characteristic of Supercritical Co2 in Semicircular/Circular Channel Under Cooling Condition

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SSRN 2022年

作者： Zhong, Shao-Geng Ren, Yan Wu, Weidong Yang, Ying-Ying Yang, Qi-Guo School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China

A mathematic-physical model was established to explore the local heat transfer characteristics of supercritical CO2 in semicircular and circular channels under cooling condition, which was applied in the field of supercritical CO2 Brayton cycle. The numerical method was validated by the experimental data with the average error of 3.79%, meeting the accuracy requirement. And the operation pressure, cooling heat flux, inlet velocity and hydraulic diameter were 8~9 MPa, 10~14 kW·m-2, 1.2~5 m·s-1 and 1~2 mm, respectively. The results showed that the local heat transfer coefficient of supercritical CO2 would increase at first and then decrease along the flow direction regardless of the semicircular channel and circular channel, and the peak value gradually decreased with increasing operation pressure and disappeared when the inlet velocity exceeded 3 m·s-1. Meanwhile, the heat transfer performance of the semicircular channel was weaker than that of the circular channel due to the influence of the corner area and the buoyant effect, and the latter played a dominant role. For the horizontal flow, the buoyant effect was increased, while the heat transfer was decreased with increasing hydraulic diameter of the semicircular channel. Besides, the influence of different flow directions on the heat transfer performance of the semicircular channel (about 6.2%) was greater than that of the circular channel (about 0.48%, and could be ignored). Finally, the heat transfer correlation of the supercritical CO2 cooling process in the horizontal semicircular channel was modified by considering the influence of the dimensionless buoyancy effect and hydraulic diameter, and the prediction errors of 90% correlation calculation results were within ±14% after the modification. These results will provide some theoretical guidance on the design and optimization of the cooler for the supercritical CO2 Brayton cycle system. © 2022, The Authors. All rights reserved.

关键词： Heat flux