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Prediction of Pressure Drop in Heavy Oil-Water Ring Two-Phase flow Based on Modified Two-Fluid Model

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SSRN 2024年

作者： Fu, Jiqiang Du, Mingjun Jing, Jiaqiang Sun, Jie Liu, Huichao Chen, Yongjiu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China China Petroleum Engineering & Construction Corp North Company Heibei Renqiu062552 China School of Oil & Natural Gas Engineering Southwest Petroleum University Sichuan Chengdu610500 China

Accurate prediction of pressure drop of the heavy oil-water ring flow in pipeline is of great significance for establishing an optimal drag reduction model and ensuring safe production. The effects of different factors on the flow pattern and pressure drop of heavy oil-water annular two-phase flow were systematically analyzed, and a standard two-fluid pressure drop prediction model for annular flow was established. By modifying the shear stress equation of oil-water interface and introducing the wave-flow theory to modify the shear stress equation of water wall, a pressure drop prediction model for the generalized concentric water ring was obtained to calculate the periodic fluctuations of oil phase. Furthermore, by introducing the comprehensive Reynolds number expression of eccentric water ring, the pressure drop prediction model for the generalized eccentric water ring was obtained to calculate the periodic fluctuations of oil phase. The results show that the pressure drop prediction accuracy of the concentric water ring for ultra-heavy oil is improved by 80 % by using the modified pressure drop prediction model. The comprehensive Reynolds number expression of eccentric water ring can effectively reflect the influence of eccentric effect on shear stress of water wall and the calculation error is less than 20 % by predicting the pressure drop of the generalized eccentric water ring with different density differences. © 2024, The Authors. All rights reserved.

关键词： Two phase flow

Corrosion Effect Analysis on Thermal-Hydraulics of Lbe/Water Spiral Tube Steam Generator Under Oxygen-Controlled Environment

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SSRN 2023年

作者： Lu, Dingsheng Yang, Yupeng Wang, Chenglong Zhang, Dalin Qiao, Pengrui Tian, Wenxi Qiu, Suizheng Su, Guanghui H. School of Nuclear Science and Technology Shanxi Key Laboratory of Advanced Nuclear Energy and Technology Xi'an Jiaotong University Xi'An710049 China China Institute of Atomic Energy Beijing102413 China State Key Laboratory of Multiphase Flow in Power Engineering China

In order to explore the flow and heat transfer characteristics of spiral tube steam generators under Lead-Bismuth Eutectic (LBE) corrosion, the accelerated removal effect of LBE corrosion flow was perfected, and a bidirectional coupling model of LBE corrosion and flow heat transfer was established. Computational fluid dynamics (CFD) method was used to simulate the corrosion and flow heat transfer of helical tube steam generator under saturated oxygen concentration and oxygen-controlled environment. The results indicate that the corrosion of liquid LBE forms an oxidation layer, which hinders the heat transfer in the spiral tube steam generator. This leads to a significant increase in the wall friction coefficient and a decrease in the surface Nusselt number. However, it does not have a significant effect on the water side evaporation process of the spiral tube steam generator. The implementation of an oxygen-controlled environment can effectively reduce the influence of LBE corrosion on the flow heat transfer of the spiral tube steam generator. Especially under high temperature conditions, it can reduce the near wall temperature of LBE change by up to 57.5% and the outlet temperature change by up to 61.5%. The oxygen-controlled environment results in prolonged local hypoxia time, with a more pronounced effect at higher temperatures. © 2023, The Authors. All rights reserved.

关键词： Oxygen

Thermodynamics analyses on a novel CHP system integrated with multi-grade thermal energy storage

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Journal of Energy Storage 2025年 106卷

作者： Liu, Rongtang Zhang, Kezhen Qin, Yuanzhi Wan, Kaidi Xu, Can Liu, Ming Ningbo Institute of Technology Beihang University Ningbo315800 China Xi'an Thermal Power Research Institute Co. Ltd. Xi'an710054 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Dongfang Boiler Co. Ltd. of Dongfang Electric Group Chengdu611731 China

The high penetration level of intermittent renewable power necessitates the crucial requirement for combined heat and power systems to possess both high efficiency and flexibility. However, the heat-controlled operation modes of traditional combined heat and power systems impose limitations on their efficiency and flexibility. Therefore, it is of great significance to develop a heat-power decoupling technology that exhibits exceptional efficiency and flexibility. A novel combined heat and power system integrated with multi-grade thermal energy storage is proposed in this study. Thermodynamic analysis models of all operational conditions are developed, and the comprehensive characteristics of efficiency and operational flexibility for the proposed system are assessed by taking a 330 MW system as an example. Results show that the proposed system can decrease/increase 16.05 MW/30.96 MW power loads comparing with the reference system during the charging/discharging periods under the design condition. Energy efficiency of the proposed system can reach 49.40 %, which is improved by 1.66 percentage points. Exergy analysis reveals the exergy destruction order for the proposed system, and shows that the combustion and heat transfer in the boiler are the major process of exergy dissipation. Moreover, operation strategies of the proposed system during charging-discharging cycle are explored and formulated under off-design condition, suggesting that thermodynamic performances of the novel system under various conditions even extreme conditions exhibits exceptional properties. The maximum heat load of the proposed system can be improved by 46.78 % comparing with the reference system, and the maximum improvement of power load capacity during charging-discharging cycle is 14.58 percentage points. This study provides a promising approach for multi-grade thermal energy storage to improve the comprehensive characteristics of combined heat and power systems. © 2024

关键词： Charge storage

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

Thermal-Mechanical Influence Aspects and Evaluation of Helical Cruciform Single Rod in Fluoride-Salt-Cooled High-Temperature Advanced Reactor

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SSRN 2024年

作者： Chen, Yiwen Zhang, Dalin Jiang, Dianqiang Li, Wei Wu, Xiaoli Tian, Wenxi Qiu, Suizheng Su, Guanghui Lu, Qi 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 State Key Laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong University Xi’an710049 China Science Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China China

Helical cruciform fuels are novel in nuclear reactors, potential to increase reactor’s power density. However, the geometry is complicated so influence of it on the fuel performance is not identified yet. In this paper, impact of power density, cross-section parameters, and twist pitch on thermal and mechanical characteristics of fuel used in Fluoride-Salt-cooled high-Temperature Advanced Reactor is discussed based on fluid-thermal-mechanical coupling. For thermal features, twist pitch is key while others have few effects. Increase in twist pitch leads to temperature uniformity and rise owing to weaker mixing effects. Fuel center temperature at middle plane of 300mm-pitch rod is 829.58℃, 54.66℃ higher than that of 100mm-pitch rod. Difference of maximum and minimum temperature at 45° cross section of 500mm-pitch rod is 153.62℃, while the figure is only 74.00℃ of 300mm-pitch rod. Besides, axial temperature of cladding outer surface increases wavelike due to complex geometry. For mechanical features, not geometry sizes but temperature affects stress distribution. Maximum Von-Mises stress appears at the elbow, where maximum temperature exists, 116.8MPa under normal conditions, lower than tensile strength of the material. After identifying the influence of these factors, five dimensionless parameters are proposed to evaluate and rate fuel performance based on Technique for Order Preference by Similarity to an Ideal Solution. As a result, an optimization comes up, scoring 0.310, twice more than the original design, owing to the thermal uniformity and mechanical safety. This study provides a reference for identifying and evaluating the performance of helical structure. © 2024, The Authors. All rights reserved.

关键词： Geometry

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

Transient Cooling Performance of R134a Flash-Evaporation Spray Enhanced by Cold Air Jet: A Novel Heat Transfer Enhancement Method in Laser Dermatology

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SSRN 2022年

作者： Li, Bufa Wang, Junfeng Tian, Jiameng Chen, Bin Xu, Haojie School of Energy and Power Engineering Jiangsu University Zhenjiang212013 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

Nevus of Ota is a dermal hyperplastic pigmented disease with a morbidity rate of 0.1%–0.6% in the Asian population. Laser surgery with the assistance of cryogen spray cooling (CSC) is a potential clinical treatment for nevus of Ota. However, for Asians with high melanin content, it is necessary to enhance cooling capability without the increment of refrigerant amount. In this study, a R134a flash-evaporation cryogen spray cooling coupled with cold air jet (CSC-CAJ) was developed to improve the cooling capacity. Epoxy resin was employed as a skin phantom to investigate the heat transfer characteristics of CSC-CAJ with different air jet parameters. Air jet parameters of CSC-CAJ are recommended to be T a = -7 °C, V a = 3 m 3 /h Z a = 10 mm and Φ a = 30°. Compared to CSC, CSC-CAJ could reduce the minimum surface temperature from -39 °C to -42.1 °C, and the average value of convection heat transfer coefficient ( h ) of CSC-CAJ could increase from 8 W/(m 2 ·k) to 12.9 W/(m 2 ·k) or 61.3% for the recommended parameters. The liquid film residence time ( τ ) decreases from 301 ms to 234 ms or 23.3%. In addition, based on the visualization observation and surface heat transfer measurement, the frost formation phenomenon on the surface and the heat transfer enhancement mechanisms are well understood. Four modes, including Leidonfrost mode, no runoff mode, runoff mode and evaporation mode, are proposed to describe the four stages of CSC-CAJ. A non-dimensional correlation of normalized Nusselt number ( Nu *) and time ( t *) is summarized. The primary heat transfer enhancement mechanism of CSC-CAJ is found to be the increase in cryogen evaporation rate and the ratio of heat removal from the phantom surface to phase change latent heat. © 2022, The Authors. All rights reserved.

关键词： Evaporation

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

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

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

Conducting Polymers Meet Lithium-Sulfur Batteries:Progress,Challenges,and Perspectives

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Energy & Environmental Materials 2023年第5期6卷 159-182页

作者： Xin Chen Chengcheng Zhao Kai Yang Shiyi Sun Jinxin Bi Ningrui Zhu Qiong Cai Jianan Wang Wei Yan Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049China Xi'an Key Laboratory of Solid Waste Recycling and Resource Recovery Department of Environmental EngineeringXi'an Jiaotong UniversityXi'an 710049China Advanced Technology Institute University of SurreyGuildfordSurrey GU27XHUK College of Arts College of Landscape Architecture Fujian Agriculture and Forestry UniversityFuzhou 350108China Department of Chemical&Process Engineering Faculty of Engineering and Physical Sciences University of SurreyGuildford GU27XHUK

Lithium-sulfur(Li-S)batteries have attracted increased interest because of the high theoretical energy density,low cost,and environmental *** polymers(CPs),as one of the most promising materials used in Li-S batteries,can not only facilitate electron transfer and buffer the large volumetric change of sulfur benefiting from their porous structure and excellent flexibility,but also enable stronger physical/chemical adsorption capacity toward polysulfides(LiPSs)when doped with abundant heteroatoms to promote the sulfur redox kinetics and achieve the high sulfur *** review firstly introduces the properties of various CPs including structural CPs(polypyrrole(PPy),polyaniline(PANi),polyethylene dioxothiophene[PEDOT])and compound CPs(polyethylene oxide(PEO),polyvinyl alcohol(PVA)and poly(acrylic acid)[PAA]),and their application potential in Li-S ***,the research progress of various CPs in different components(cathode,separator,and interlayer)of Li-S batteries is systematically ***,the application perspective of the CPs in Li-S batteries as a potential guidance is comprehensively discussed.

关键词： conducting polymers Li-S batteries modified materials polysulfides