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Experimental Study of Liquid Immersion Cooling for Different Cylindrical Lithium-Ion Batteries Under Rapid Charging Conditions

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SSRN 2022年

作者： Li, Yang Bai, Minli Zhou, Zhifu Lv, Jizu Hu, Chengzhi Gao, Linsong Peng, Chunyang Li, Yulong 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

In this study, the fluorinated liquid immersion cooling scheme has been proposed and tested for cooling the six different types of cylindrical lithium-ion batteries (LIBs) under fast charging conditions. SF33, with the boiling point of 33.4 °C, is chosen as the fluorinated liquid for the immersion cooling. Firstly, the voltage and temperature responses of LIBs under fast charging conditions with natural convection and SF33 immersion cooling were explored. It is found that the SF33 immersion cooling has a significant advantage over natural convection on controlling the battery temperature, thus ensuring the stability and safety of LIBs in the fast charging process. Subsequently, the high-speed photography was used to observe the bubble behaviors in the cooling process of SF33, and the heat transfer mechanism in the two-phase heat transfer process corresponding to immersion cooling of LIB was preliminary analyzed and discussed. It can be concluded that when the charging current is higher, the phenomenon of subcooled boiling as well as saturation boiling is generated in the SF33. The transition from single-phase convective heat transfer to boiling heat transfer greatly increases the heat transfer coefficient. © 2022, The Authors. All rights reserved.

关键词： Liquids

Heavy Oil Upgrading Using Naoh/Cuso4 Composite Catalyst in Aquathermolysis

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SSRN 2022年

作者： Zhou, Yantao Zhao, Qiuyang Miao, Yan Wang, Xuetao Zhang, Yanlong Wang, Yechun 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 Foshan528216 China

To obtain an inexpensive and efficient catalyst in the in-situ upgrading of heavy oil, the NaOH/CuSO4 composite catalyst was proposed in this work. Firstly, the experiments found the viscosity of heavy oil increased with addition of CuSO4 under 300°C in aquathermolysis. Then, the addition of NaOH was found to improve the catalyst capacity of CuSO4 significantly. The NaOH/CuSO4 decreased the viscosity by 81.43% under 300°C. The further analysis revealed the Cu atoms of CuSO4 enter into the heavy oil molecules to increase viscosity, and the NaOH inhabits the viscosity increasing reaction. Besides, the Cu and CuOx with a higher catalytic capacity produced with the addition of NaOH. These conclusions are helpful to understand the aquathermolysis upgrading mechanism and develop a type of inexpensive and efficient composite catalyst. © 2022, The Authors. All rights reserved.

关键词： Sulfur compounds

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

A Novel Water Content Sensor Design and its Application for In-Situ Water Content Measurement Inside the flow Channel of Pemfc

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SSRN 2022年

作者： Zhang, Yan Wang, Weiding Liu, Yukai Su, Jinzhan International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering School of Energy & Power Engineering Xi’an Jiaotong University Xi’an710049 China

In-situ water content detection in proton exchange fuel cell (PEMFC) is of great importance to its water management. In this study, flexible thin film water content microsensor (WCMS) were fabricated and deployed for real-time measurement of water distribution inside the channel of proton exchange membrane fuel cells. The effect of inserting WCMS on the cell performance was confirmed to be negligible. Besides, three WCMS were used to monitor the variation of water distribution in the upstream, midstream and downstream of the flow channel, respectively. The experimental results show that the WCMS can efficiently detect the change of water content inside the fuel cell in real time. The co-occurrence phenomenon of water column clogging in the flow channel and degradation of cell performance were observed. This work provide a novel design of WCMS and its application on the water content distribution inside flow channel of fuel cells. © 2022, The Authors. All rights reserved.

关键词： Proton exchange membrane fuel cells (PEMFC)

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

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

Tuning the local electronic structure of oxygen vacancies over copper-doped zinc oxide for efficient CO_(2) electroreduction

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eScience 2022年第5期2卷 518-528页

作者： Ke Wang Dongyu Liu Limin Liu Jia Liu XiaoFei Hu Ping Li Mingtao Li Andrey S.Vasenko Chunhui Xiao Shujiang Ding Xi'an Key Laboratory of Sustainable Energy Materials Chemistry School of ChemistryEnergy Storage Materials and Chemistry of Shaanxi University Engineering Research CenterXi'an Jiaotong University28 Xianning West RoadXi'an710049China International Research Center for Renewable Energy(IRCRE) State Key Laboratory of Multiphase Flow in Power Engineering(MFPE)Xi'an Jiaotong University28 Xianning West RoadXi'anShaanxi710049China HSE University 101000MoscowRussia College of Materials and Environmental Engineering Hangzhou Dianzi UniversityHangzhou310018PR China CNNC Shaanxi Uranium Enrichment Co. Ltd.HanzhongChina

Oxygen vacancies in metal oxides can serve as electron trap centers to capture CO_(2) and lower energy barriers for the electrochemical CO_(2) reduction reaction(CO_(2)RR).Under aqueous electrolytes,however,such charge-enriched active sites can be occupied by adsorbed hydrogen(H∗)and lose their effectiveness for the CO_(2)***,we develop an efficient catalyst consisting of Cu-doped,defect-rich ZnO(Cu–ZnO)for the CO_(2)RR,which exhibits enhanced CO Faradaic efficiency and current density compared to pristine *** introduced Cu dopants simultaneously stabilize neighboring oxygen vacancies and modulate their local electronic structure,achieving inhibition of hydrogen evolution and acceleration of the CO_(2)*** a flow cell test,a current density of more than 45mAcm^(−2) and a CO Faradaic efficiency of>80%is obtained for a Cu–ZnO electrocatalyst in the wide potential range of−0.76V to−1.06V *** Hydrogen Electrode(RHE).This work opens up great opportunities for dopant-modulated metal oxide catalysts for the CO_(2)RR.

关键词： CO_(2)electroreduction Oxygen vacancy Heteroatom doping Metal oxide catalysts

Interlink between Abnormal Water Imbibition in Hydrophilic and Rapid flow in Hydrophobic Nanochannels

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Physical Review Letters 2024年第18期132卷 184001-184001页

作者： Runfeng Zhou Mehdi Neek-Amal Francois M. Peeters Bofeng Bai Chengzhen Sun State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China Department of Physics Shahid Rajaee Teacher Training University 16875-163 Lavizan Tehran Iran Departement Fysica Universiteit Antwerpen Groenenborgerlaan 171 B-2020 Antwerpen Belgium Departamento de Física Universidade Federal do Ceará Fortaleza-CE 60455-760 Brazil

Nanoscale extension and refinement of the Lucas-Washburn model is presented with a detailed analysis of recent experimental data and extensive molecular dynamics simulations to investigate rapid water flow and water imbibition within nanocapillaries. Through a comparative analysis of capillary rise in hydrophilic nanochannels, an unexpected reversal of the anticipated trend, with an abnormal peak, of imbibition length below the size of 3 nm was discovered in hydrophilic nanochannels, surprisingly sharing the same physical origin as the well-known peak observed in flow rate within hydrophobic nanochannels. The extended imbibition model is applicable across diverse spatiotemporal scales and validated against simulation results and existing experimental data for both hydrophilic and hydrophobic nanochannels.

关键词： Imbibition & injection Nanofluidics Molecular dynamics Navier-Stokes equation

Numerical simulation of bubble behavior in a quasi-2D fluidized bed using a bubble-based EMMS model

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Particuology 2019年第5期17卷 40-54页

作者： Hao Wang Youjun Lu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi'an 710049 Shaanxi China

Bubbles formed during chemical processes in fluidized beds govern the bed hydrodynamics and opera-tional efficiency, thereby having a significant impact on their design and scale-up. In this study, a two-fluid model was used to simulate the bubble behavior in a quasi-two-dimensional fluidized bed within the bubble-based energy minimization multiscale (EMMS) approach. We performed experiments to verify the model and proposed a correlation of the heterogeneous index for various parameters to calculate the coefficient of drag for the bubble-based EMMS model. Moreover, the simulation results obtained from the homogeneous drag models and EMMS bubbling model were compared with experimental data and empirical correlations. The simulation results of the EMMS approach showed good agreement with the experimental data in the distribution of the vertical bubble velocity with chord length. Compared with the results from the homogeneous models, the distributions of vertical velocity and diameter of the bubbles predicted by the EMMS-bubbling model were in better agreement with empirical correlations. Moreover, the frequency distributions of bubble properties including bubble diameter, aspect ratio, and shape factor for different gas-inlet velocities were obtained.

关键词： Energy minimization multi-scale approach Heterogeneous index Fluidized bed Bubble