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Applied Thermal engineering 2025年 261卷

作者： Hengyuan Wang Qiyu Xuan Hailin Lei Xi Li Zhibin Li Huixiong Li State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China

Thermal management performance and optimization of a hybrid system integrating liquid cooling and fin-enhanced phase change material for large-capacity energy storage battery pack

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Energy Conversion and Management 2025年 336卷

作者： Lin, Xiang-Wei Zhou, Zhi-Fu Liu, Maochang Chen, Bin Lu, You-Jun Jing, Deng-Wei Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Battery energy storage systems become increasingly important to address the intermittency of renewable energies, but their widespread adoption is still hindered by thermal concerns. However, a single thermal management strategy cannot ensure the overall performance of energy storage battery systems. In this study, a hybrid strategy combining topological fin structure, phase change material, and active liquid cooling is established for 280 Ah lithium-ion battery pack. A fluidic-thermal-phase change coupled model is built and verified experimentally. Meanwhile, a novel comprehensive evaluation parameter is defined to feature the overall performance of thermal management system. Based on this, comparative investigations are conducted to assess the efficiency of three cooling strategies. Despite additional weight caused by hybrid design, topological fin structure not only constructs the thermal conduction in phase change material but also dissipates the accumulated heat by connecting cold plate. Additionally, the impacts of fin fraction, thickness of phase change material, and inlet velocity are systematically explored using single-factor analysis. Furthermore, a surrogate-based model is utilized to reveal the interactions between design parameters and system performance, while accomplishing a global optimization. In contrast to original design, comprehensive evaluation parameter is reduced by 0.218, 0.273, 0.256, and 0.2 for discharge rates of 0.25, 0.5, 0.75, and 1C, respectively. © 2025 Elsevier Ltd

关键词： Battery 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 Wei, Lei 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 Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 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

Insight into the key Role of Imine Groups in Polyaniline for Adsorbing Heavy Metal Ions: Experimental and Density Functional Theory Study

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SSRN 2023年

作者： Shi, Bofang Li, Hang Fu, Xiaojie Zhao, Chengcheng Rao, Yongfang Li, Mingtao Komarneni, Sridhar Yang, Honghui Xi’an Key Laboratory of Sustainable Energy Materials Chemistry Department of Applied Chemistry School of Chemistry Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Department of Environmental Science and Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Ecosystem Science and Management Materials Research Institute 204EEL The Pennsylvania State University University ParkPA16802 United States

In polyaniline (PANI) or polyaniline-based adsorbents, the views on nitrogen group that has the highest chemical affinity to heavy metal ions and dominates the adsorption process remain in debate. Herein, we focus on deciphering the main adsorption sites and adsorption mechanism of PANI using both experiments and density functional theory (DFT) calculations. The characterization results of adsorption product demonstrate that the metal ions were adsorbed via coordination bond between nitrogen atom and metal ion. The theoretical calculations by DFT reveal that −N= group is the key adsorption site rather than other groups in PANI, and the key step of PANI adsorption process is a ligand exchange reaction. The H+ ions with a higher affinity to −N= group can inhibit the adsorption of metal ions due to the consumption of adsorption sites and ion exchange reaction. This work provides a molecular-level understanding of adsorption sites, adsorption mechanism, and H+ competition for metal ion adsorption by PANI, which is beneficial for the development of PANI-based adsorbents. © 2023, The Authors. All rights reserved.

关键词： Density functional theory

Flow and residence time distribution characteristics in continuous hydrothermal reactor under different heating schemes

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Chemical engineering Science 2025年 316卷

作者： Li, Yi Wang, Junying Li, Xiaoyu Jin, Hui State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi710049 China

Residence time distribution (RTD) is of significance for reflecting materials or intermediate products dispersion and actual reaction time inside continuous hydrothermal reactors of supercritical water gasification technology. Generally, RTD is strictly related to flow field, which can be affected by wall heating schemes. In order to propose methods to regulating RTD, effects of different heating schemes on flow and RTD characteristics are investigated and compared by numerical simulation. The results indicate that increasing heat flux, interrupting boundary flow by interlace heating, and setting cooling walls can significantly regulate RTD. By analyzing the correspondence of flow and RTD, the mechanisms of increasing materials and intermediate products dispersion can be attribute to the increase of flow instability and the generation of additional vortices. For example, in the cases of present work, the narrow-strip double-vortex generated by mixing between thermal boundary flow and branch flow may significantly increase average residence time and materials distribution range from 10.93 s and 1.00 to 22.83 s and 1.51. In the region above branch inlet without time-averaged vortex structure, the increasing of flow instability caused by wall heating is observed to widen materials distribution range from 0.75 to 0.99. Heating scheme customized according to these mechanisms can regulating RTD as expected, proving the feasibility and significance of regulating RTD by heating schemes. © 2025

关键词： Reaction intermediates

Microscopic characteristics study of liquid ammonia spray under different flash boiling conditions

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Fuel 2025年 401卷

作者： Liu, Xiao Zeng, Gangwei Yao, Xiaoxin Tang, Chenglong Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Liquid ammonia, as a zero-carbon fuel, has received widespread attention in the field of internal combustion engines. The development of ammonia spray and evaporation models urgently requires accurate particle size distribution data. In this study, microscopic characteristics of liquid ammonia spray were firstly experimentally investigated under conditions of high injection pressure (up to 80 MPa) and ambient pressure (up to 4 MPa) with a single-hole injector (0.3 mm). Statistical results of microscopic parameters, including Sauter Mean Diameter (SMD), characteristic droplet diameter, and droplet number density were obtained over a wide range. The results indicate that ambient pressure or RP significantly affects the microscopic characteristics of ammonia spray. In flare flash boiling region (pressure ratio RP ≤ 0.3), ammonia spray produces more droplets with smaller diameter and the statistical SMD is around 15 μm. The droplet size increases and number density decreases with the increasement of ambient pressure or RP. In the transition flash (0.3 P ≤ 1) and non-flash boiling region (RP > 1), the SMD statistical results are approximately 20 and 24 μm, respectively. Increasing the injection pressure can promote atomization and generate more smaller droplets, with a more uniform distribution. Ambient temperature slightly affects the microscopic characteristics of liquid ammonia spray within the temperature range selected for this study, but evaporation becomes more pronounced as the ambient temperature increases. The wide range droplet size distribution and SMD are believed to provide important data for ammonia spray modeling and simulation. © 2025

关键词： Internal combustion engines

Xct Images-Based Pore-Scale Numerical Investigation for Heat Transfer Using Copper Foam Filled with Paraffin Phase Change Material

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SSRN 2024年

作者： Liu, Xinyu Zhou, Zhifu Wu, Wei-Tao Wei, Lei Hu, Chengzhi Lyu, Jizu Huang, Heng 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 Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China

The principle of phase change heat transfer using copper foam in the paraffin phase change material (PPCM) are not well understood. In this study, based on X-ray computed tomography (XCT), three dimensional (3D) geometric model of copper foam was established, including PPCM domain. We developed a coupled fluid-solid model to explore phase change for heat transfer in the composite phase change material (CPCM) with copper foam and PPCM. The effects of phase change melting behavior, heat transfer characteristics and homogeneity of temperature were considered. Results of numerical simulation demonstrated that the CPCM had completely melted at 669.8 s. Here the melting time decreased by 45%, compared with the pure PPCM at 1218 s. The extensive heat transfer contact area was offered by the copper foam skeleton. Meanwhile, the melting durations of the CPCM ranged from 4368 s, 2236.3 s, 509.4 s, and 284.6 s corresponding to the heat fluxes with 500 W/m2, 1000 W/m2, 5000 W/m2, and 10000 W/m2. The melting process correlated directly with the heat flux, making it adaptable to the operational demands of diverse electronic components. © 2024, The Authors. All rights reserved.

关键词： Heat flux

Under-Deposit Corrosion Behavior and Dynamic Deliquescence Properties of Ammonium Salts Covered on Pipelines and Components in a Crude Oil Distillation Column: Experimental and Theoretical Studies

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SSRN 2022年

作者： Li, Ruidong Chen, Jukai Wang, Yueshe State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi'An710049 China School of Chemical Engineering & Technology China University of Mining and Technology Xuzhou221116 China

Electrochemical experiments based on the interdigital electrodes of SAE 1020 steel and atomic simulation were performed to investigate the under-deposit corrosion behavior and dynamic deliquescence properties of ammonium salts. In-situ electrochemical measurements demonstrate that the deliquescence of ammonium salts affects the evolution of the interface, and the surface characterization results proved that the critical state of moisture absorption leads to the most severe corrosion. Additional ab initio molecular dynamics simulations suggest that the H transport chain impacted by the hydrolysis of NH4+ leads to a variation in the charge state of the system, which may triggering corrosion. © 2022, The Authors. All rights reserved.

关键词： Steel corrosion

Identification of flow cut-off pattern and prediction of cut-off time of gas-liquid two-phase flow in pipeline-riser system

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Physics of Fluids 2025年第5期37卷

作者： Liu, Tianyu Wang, Hanxuan Zou, Suifeng Du, Yaohua Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

For offshore pipeline-riser systems, cyclic flow cut-off in slugging flow pattern should be identified and necessarily mitigated to satisfy the requirement of normal operation of gas-liquid separator. Since conventional studies on flow pattern identification were not directly related to the harmfulness of slugging and the decision of flow control, this study develops a risk assessment method for offshore riser systems based on the characteristic parameters of riser outlet signals, achieving an identification accuracy exceeding 90% at different valve openings. Notably, the method maintains exceptional performance under high-pressure conditions, with identification accuracy reaching 96.74% at 10 MPa. On the other hand, this study focuses on the prediction of cut-off duration time in a cycle instead of the cycle period. We establish a predictive model for flow cut-off duration time under different choking conditions. Validation across diverse pipeline systems demonstrates strong reliability of the model, exhibiting maximum prediction errors of 30%. The model's coefficients can be fitted by a small dataset without significant loss of accuracy, and the coefficients are conservative, indicating strong applicability in the field operation. These findings offer significant theoretical insights and practical solutions for enhancing the operational safety of offshore oil and gas transportation systems. © 2025 Author(s).

关键词： Marine risers

Simulations on Hybrid Thermal Management of Mini-Channel Cold Plate and Pcm for Lithium-Ion Batteries Under Discharging and Thermal Runaway Conditions

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SSRN 2024年

作者： Liu, Yang Zhou, Zhifu Wu, Wei-Tao Wei, Lei Lyu, Jizu Li, Yang Liu, Xinyu Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation 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 Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen518055 China School of Mechanical Engineering Guangdong Ocean University Zhanjiang524088 China

In this study, we compared the performance of different structures of mini-channel cold plate (MCP)- phase change material (PCM) hybrid thermal management on discharge and thermal runaway. The heat transfer structures for them can be categorized into three types: (a) uncoupled, (b) semi-coupled, and (c) fully coupled. Among these, the semi-coupled design B exhibits the best performance. Specifically, in the high rate discharge condition, the structure can control the battery temperature at 44.37°C at low coolant mass flow rate, and the temperature at 36.47°C at high mass flow rate, while the temperature difference (TD) of a single cell does not exceed 2.01°C. In a low-multiplier discharge zero-energy system, the pack temperature rise can be limited to no more than 10°C in 35°C environment. Under external short-circuit conditions, a lower coolant mass flow rate is sufficient to keep the pack temperature at 43.22°C. Under internal short-circuit thermal runaway (TR), lower coolant mass flow rate can prolong the TR of the adjacent cell up to 521 s, and higher mass flow rate can completely inhibit the occurrence of TR. The objective of this study is to offer valuable references for the design and implementation of hybrid MCP-PCM cooling systems. © 2024, The Authors. All rights reserved.

关键词： Phase change materials