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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

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

Experimental Study on Liquid Immersion Preheating of Lithium-Ion Batteries Under Low Temperature Environment

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SSRN 2024年

作者： Bao, Jiakang Zhou, Zhifu Wu, Wei-Tao Wei, Lei Jizu, Lyu Li, Yang 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

In this paper, a single-phase immersion preheating experimental test platform is constructed to analyze the immersion preheating, the preheating performance, and the energy consumption. Immersion preheating has a major improvement on the low-temperature performance of the lithium cell, and the warming rate during preheating varies depending on the temperature (-25°C, -15°C, -5°C, 5°C, 15°C, 25°C) is very close to each other. The inlet temperature has a greater influence on the preheating performance than other factors, increasing the inlet temperature is favorable to rate of warming, but will increase the cell safety risks. flow rate and battery spacing increases on the rate of increase in temperature of the impact is gradually weakened, the rising inlet flows on the battery pack module temperature difference has a greater impact, the spacing increases on the battery cell and the battery pack temperature difference is gradually reduced, even so the maximum battery temperature difference is still controlled to 6℃ or less. In addition, immersion preheating has lower utilization of heat and higher energy consumption, and the preheating energy consumption at ambient temperature -25℃ has exceeded 80 % of the rated capacity of experimental battery packs. © 2024, The Authors. All rights reserved.

关键词： Energy utilization

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

Thermophysical property prediction of supercritical multiple mixtures fluid by molecular dynamics simulation

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Journal of Molecular Liquids 2025年 432卷

作者： Gui, Tete Li, Jiasunle Ge, Zhiwei Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Supercritical multiple mixtures (H2O/CO2) fluids are produced in the poly-generation system based on supercritical water gasification (SCWG). Understanding the thermophysical property of supercritical multiple mixtures fluid is rather essential to design and industrialize the poly-generation system. At present, the selection of force field models for H2O/CO2 mixtures are rather complicated, chaotic and inconsistent, the calculation of each parameter necessitates the use of one force field model. There is no universal force field model to calculate and conduct thermophysical property of H2O/CO2 at one time in a wide range of temperature within SCW. In this paper, heat capacity, viscosity and thermal conductivity of multiple mixtures in supercritical and near-critical water (575 K–1075 k) are first investigated via a novel common force field model with molecular dynamics (MD) simulations. The effects of different factors including the pressure, temperature and CO2 mass fraction on thermophysical properties of H2O/CO2 at a wide range of temperature were first analyzed and conducted in detail. The calculated results indicate that the phenomenon "critical point drift" for viscosity and thermal conductivity of H2O/CO2 mixtures migrating toward the low temperature region occurs. The drift values of viscosity and thermal conductivity are about 10 K and 28 K. The variation of heat capacity and viscosity of H2O/CO2 mixtures increases with increasing pressures only in low temperatures region (700 K-–800 K), while the thermal conductivity always increases with increasing pressures. When the mass fractions of CO2 increases from 20 % to 40 % and 60 %, the drift values for thermal conductivity and viscosity of H2O/CO2 mixtures decreases from 628 K to 624 K and 620 K, and from 627 K to 618 K and 610 K, respectively, and the peak heat capacity decreases from 64.9 J/mol·K to 52.4 J/mol·K and 45.1 J/mol·K. The fitting polynomial to determine conductivity, viscosity and heat capacity H

关键词： Temperature distribution

ȮH insights into the interaction of hydrogen-rich methane and water: Laser absorption experiments and chemical kinetics

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Combustion and Flame 2025年 278卷

作者： Zhang, Xin Feng, Zilong Hong, Congjie Sun, Wuchuan Huang, Zuohua Zhang, Yingjia State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Flue gas recirculation and steam injection are employed in hydrogen-rich gas turbines to stabilize fuel reactivity and improve cycle efficiency, introducing high water vapor content into the combustion chamber and thereby necessitating an investigation of water-fuel interactions at elevated temperatures. This study employed UV laser absorption diagnostics behind reflected shock waves to conduct in situ measurements of the ȮH concentration time-histories during the oxidation of CH4/H2/H2O/O2/Ar mixtures at pressures of approximately 1.3, 5.0, and 15.2 atm and temperatures ranging from 1225 to 1888 K with varying hydrogen blending and water addition ratios. The absorption lineshapes of the ȮH R1(5) transition in the A-X(0,0) vibronic band were characterized after broadening and shifting in Ar at different pressures, with diagnostic center wavelengths set at 306.6868 nm (1.3 atm), 306.6874 nm (5.0 atm), and 306.6886 nm (15.2 atm), respectively. The obtained ȮH concentration time-history data were compared in detail with predictions from eight representative reaction kinetic models, and the predictive capability of the models for ȮH behavior was quantitatively assessed using the error function method. NUIGMech1.1 exhibited superior performance in predicting ȮH behavior and was subsequently selected for kinetic analysis to elucidate stage-specific micro-mechanisms and identify key reactions driving the concentration evolution. The activating effect of H2 on ȮH behavior during CH4 oxidation was investigated. Results indicate that higher hydrogen levels intensify hydrogen-related reaction pathways, expanding the radical pools (H, ȮH, and Ö), thereby promoting fuel consumption through Ḣ-atom abstraction reactions. Additionally, by introducing weak collision H2O* and inert H2O**, the thermodynamic and kinetic effects of water were distinguished. The results show that under the current conditions, H2O primarily affects ȮH behavior through direct participation in reactions rat

关键词： Equilibrium constants

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

Waterside Corrosion of M5 Alloy in Simulated Primary Coolant and Supercritical Water: Influences of Aqueous Environments

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SSRN 2022年

作者： Jiang, Guanyu Liu, Lu Xu, Donghai Li, Yanhui Kuang, Wenjun Wang, Mingjun Key Laboratory of Thermo-Fluid Science & Engineering Ministry of Education School of Energy and Power Engineering Xi’an Jiaotong University Shaanxi Province Xi’an710049 China State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'An710049 China State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and Technology Xi'an Jiaotong University Xi'An China

M5 alloy is highly potential to serve as cladding materials in nuclear reactors. In this work, corrosion characteristics of M5 alloy in lithiated/borated water and pure supercritical water were investigated, and influences of aqueous environments on the corrosion process were clarified. Oxide films formed on the alloy mainly consisted of m-ZrO2. In the coolant environment, Li+ and OH- shared a synergistic effect on the occurrence and acceleration of waterside corrosion. Boric acid can react with OH- to induce B-(OH) formation and participate in the generation of zirconium borate to alleviate the accelerated corrosion effect by LiOH. In supercritical water, M5 alloy showed weight loss due to localized oxide exfoliation, and dissolved oxygen resulted in serious pitting of the oxide film. The microcrack density and porosity were significantly larger than those in the coolant environment, and long transverse cracks parallel to the O/M interface existed. Oxide deposition in two environments was both observed, and the phenomenon was discussed. © 2022, The Authors. All rights reserved.

关键词： Coolants

Revised control strategy for coal-fired power plants during transient processes considering heat transfer deterioration of cooling wall: Flexibility enhancement and security operation

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International Journal of Heat and Mass Transfer 2025年 251卷

作者： Wang, Dengliang Zhao, Yongliang Gao, Wei Chen, Weixiong Wang, Chaoyang Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

The increasing integration of intermittent renewable energy sources has heightened the need for enhanced deep peaking and operational flexibility within thermal power plants. This trend poses an enormous threat to the safe operation of boilers, especially cooling wall, underscoring the critical importance of scrutinizing the thermo-hydraulic performance of cooling walls during transient operations. In this study, a 1100 MW ultra-supercritical thermal power plant is used as the research object. A comprehensive one-dimensional dynamic model of the cooling wall is devised, grounded in fundamental principles encompassing mass conservation, momentum conservation, energy conservation, state, metal heat storage, and heat transfer Equations. The analysis yields temperature distributions of the working fluid, inner wall, and outer wall along the height direction of the cooling wall, unveiling instances of dry-out phenomenon during load cycling processes. The investigation reveals that heat transfer deterioration stands out as a primary factor behind intermittent fluctuations in metal wall temperatures. At load cycling rates of 2.5% Pe/min and 3.0% Pe/min, the maximum temperatures of the metal tube wall during the loading up process surge to 527.9°C and 557.3°C, respectively. Furthermore, a revised control strategy is proposed based on the identified heat transfer deterioration characteristics of the cooling wall. Notably, during the loading up process, the peak wall temperature is substantially curtailed from 557.3°C to 502.2°C at a rate of 3.0% Pe/min. This strategic adjustment results in an augmented maximum power ramp rate, escalating from 2.5% Pe/min to 3.0% Pe/min, upon the adoption of the revised control strategy. © 2025 Elsevier Ltd

关键词： Fossil fuel power plants