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SSRN 2024年

作者： Tian, Liang Feng, Wenbin Han, Xiao Liu, Yuzhi Liu, Hongfang Cai, Xiao School of Energy and Environmental Engineering Hebei University of Technology Tianjin300401 China National Key Laboratory of Science and Technology on Aero-Engine Aero thermodynamics Research Institute of Aero-Engine Collaborative Innovation Center for Advanced Aero-Engine Beihang University Beijing100191 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China

Addressing climate change and reducing greenhouse gas emissions are critical priorities. Utilizing hydrogen-rich methane or pure hydrogen as fuels within gas turbines, facilitated by array micro-tube premixed combustion technology, is anticipated to markedly accelerate the decarbonization process of the energy sector. In this study, the flame structure of the array micro-tube premixed burner under various fuel compositions was examined using OH-Planar Laser-Induced Fluorescence (OH-PLIF) and Particle Image Velocimetry (PIV) measurement techniques. The effects of the equivalence ratio (φ) and the hydrogen power ratio (HPR) on the characteristics of the flame front, including its curvature, density, volume, and the associated flow field properties, were discussed. As φ and HPR increase, the wrinkled structure of the flame front is significantly enhanced, with a more pronounced effect on smaller scales. This enhancement leads to the separation of the unburned pockets from the main flame. Concurrently, both the flame length and flame area decrease with the augmentation of φ and HPR, indicating a more concentrated combustion process and increased combustion intensity under hydrogen-enriched and pure hydrogen conditions. The study also observed a slight increase in both the negative and positive curvatures of the flame front, with a more notable increase in negative curvature. The increased negative curvature results in an elevated degree of wrinkling and a higher value of Σ (flame surface density), reaching a maximum of 0.876 mm-1 under the conditions where φ is 0.8 and (mean progress variable) is 0.5, resulting in the smallest observed flame volume of 100.6 mm3. Upon coupling the flame with the flow field, it was discovered that the exit flow field of the array micro-tube exhibits symmetry and a characteristic conical flame shape. The burning velocity of the side flame brushes increases, and the velocity peak shifts upstream. The above findings confirms that the additio

关键词： flow fields

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Numerical Simulations on Hybrid Thermal Management of Mini-Channel Cold Plate and Pcm for Lithium-Ion Batteries

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SSRN 2024年

作者： Liu, Yang Zhou, Zhifu Wu, Wei-Tao Wei, Lei Li, Yang Liu, Xinyu 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

In this study, a novel battery thermal management system (BTMS), combining phase change material (PCM) and mini-channel cold plates (MCPs), was modeled and analyzed. First, the effects on single cell cooling using MCPs and PCM alone are investigated at different coolant rates, temperatures, and PCM thicknesses. Then, the hybrid thermal management system (HTMS) is developed with the aim of reducing the cooling load of the PCM through hybridization with MCPs and the optimal combination of them is investigated. At the end of this work, the thermal performance of a battery pack with a hybrid thermal management structure has been analyzed, where the cold plate can take away the heat from the PCM to restore its thermal storage capacity. The results show that the combination of 3 channel and 10 mm PCM with 0.1 m/s coolant velocity and 20°C coolant temperature is the quit suitable regarding the cooling performance. Under 2C discharging rate, this design reduces the maximum battery temperature to 40°C, which is 32.5% lower, and the average temperature to 35℃, which is 41% lower than it without cooling. The study's findings offer potential new strategies and predictions for hybrid thermal management that utilize MCPs and PCM. © 2024, The Authors. All rights reserved.

关键词： Lithium-ion batteries

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Numerical Simulations for Comparison of Cold Plate Cooling and Hfe-7000 Immersion Cooling in Lithium-Ion Battery Thermal Management

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SSRN 2024年

作者： Liu, Xinyu Zhou, Zhifu Wu, Wei-Tao Wei, Lei Hu, Chengzhi 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

In this work, fluorinated liquids can be used as a new immersion coolant for effective battery thermal management (BTM) because of their insulating and non-flammable inert characteristics. In this research, the liquid chosen for immersion cooling is HFE-7000, characterized by a boiling point of 34°C. The analysis of bubble kinetics is employed to investigate the heat transfer mechanism in two-phase immersion cooling by examining the behavior of bubbles during the boiling process. The square ternary Li-ion batteries are subjected under loads of 2C and 3C cooled by immersion cooling and a mini-channel cold plate as a comparison. It turns out that immersion liquid cooling modules offer superior thermal performance. Under constant current (CC), the peak temperature is reduced by 4.89°C and 9.31°C compared with the mini-channel cold plate cooling (CPC). Under dynamic load conditions, the maximum temperature rise of the battery is reduced by 29.89% and 43.89% compared to CPC. As a passive heat dissipation method, two-phase immersion cooling reduces the design requirements for active control. Also, it delivers an efficient battery thermal management system (BTMS) designed for upcoming electric vehicles (EVs). © 2024, The Authors. All rights reserved.

关键词： Lithium-ion batteries

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Turbulent heat transfer in a horizontal helically coiled tube

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Heat Transfer 2000年第5期28卷

作者： Bofeng Bai Liejin Guo Ziping Feng Xuejun Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University China

An experiment has been conducted in detail to study the turbulent heat transfer in horizontal helically coiled tubes over a wide range of experimental parameters. We found that the enhancement of heat transfer in the coils results from the effects of turbulent and secondary flows. With Reynolds number increasing to a high level, the contribution of the secondary flow becomes less to enhance heat transfer, and the average heat transfer coefficient of the coil is closer to that in straight tubes under the same conditions. The local heat transfer coefficients are not evenly distributed along both the tube axis and the periphery on the cross section. The local heat transfer coefficients on the outside are three or four times those on the inside, which is half of the average heat transfer. A correlation is proposed to describe the distribution of the heat transfer coefficients at a cross section. The average cross-section heat transfer coefficients are distributed along the tube axis. The average value at the outlet section should not be taken as the average heat transfer coefficient. © 1999 Scripta Technica, Heat Trans Asian Res, 28(5): 395–403, 1999

关键词： turbulent heat transfer horizontal helically coiled tube secondary flow local heat transfer

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The 6th International Symposium on multiphase flow, Heat Mass Transfer and Energy Conversion (ISMF2009)

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International Journal of Hydrogen Energy 2010年第13期35卷 7027-7027页

作者： Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University China

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Solar-Wind Energy Complementary Coupling Realizes Magnetic-Field Assisted Efficient Photocatalytic Co2 Reduction

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SSRN 2023年

作者： Kong, Biao Ren, Yuqi Liu, Maochang Zhou, Jiancheng Wang, Ke Wang, Nan Li, Naixu School of Chemistry and Chemical Engineering Southeast University No.2 Dongnandaxue Road Jiangsu Nanjing211189 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Shaanxi Xi'An710049 China

We report the synthesis of a Z-scheme monolithic photocatalyst in the form of copper foam supported TiO2 combining Cu2O and Ag nanoparticles (CF@TiO2/Cu2O-Ag). The designed catalysts with efficient charge separation show superior photocatalytic activity toward CO2 reduction, with a maximum CO yielding rate of 25.58 μmol‧g-1‧h-1. More importantly, we develop a solar-wind energy complementary device, which enables the strong coupling of the magnetic field into the photocatalytic reaction. Specifically, the in-situ space electric field generated from the wind-driven induced electromotive force further enhances the separation and transportation of photogenerated charge carriers in the Z-scheme system. The productivity of CO in the proof-of-concept device based on the use of CF@TiO2/Cu2O-Ag catalyst reaches 71.66 μmol‧g-1‧h-1. This study provides an ideal approach for reinforcing photocatalytic CO2 reduction through muti-field coupling and highlights the prospect of solar-wind energy coupled photocatalysis. © 2023, The Authors. All rights reserved.

关键词： Titanium dioxide

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Zero-Energy Nonlinear Temperature Control of Lithium-Ion Battery Based on a Shape Memory Alloy

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SSRN 2024年

作者： Li, Yang Bai, Minli Zhou, Zhifu Wu, Wei-Tao Wei, Lei Hu, Chengzhi Liu, Xinyu Gao, Shuai Li, Yubai Song, Yongchen Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian116023 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

Improving the poor performance of lithium-ion battery (LIB) in extreme temperatures is essential to promoting electric vehicles (EVs) into wider application. The most severe challenge for the existing battery thermal management systems (BTMSs) is to overcome the contradiction between excellent heat dissipation at high temperatures and effective insulation at low temperatures. Here, we propose a zero-energy nonlinear temperature control strategy based on thermal regulator. The designed thermal regulator based on shape memory alloy (SMA) can switch the heat flux on the battery surface according to its temperature without any power supply or logic control and provide the desirable thermal functions. This thermal regulator increases the battery capacity by 55.44% in the cold environment of -20℃ compared to the baseline BTMS with superior heat dissipation. Simultaneously, it can limit the battery peak temperature to near the FS49 boiling point (49℃) in the hot environment of 45℃ to ensure safety. Furthermore, we demonstrate that the thermal regulator enables thermal runaway to be effectively suppressed inside the battery, reducing the emission of combustible or toxic gases by 72.26%, which is reported for the first time. Finally, we simplify the design of the thermal regulator from the perspective of system integration and demonstrate the feasibility of the thermal regulator at the battery pack level. © 2024, The Authors. All rights reserved.

关键词： Lithium-ion batteries

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Experimental and Kinetic Modeling Study on the Oxidation and Laminar Combustion Characteristics of Natural Gas

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SSRN 2023年

作者： Chen, Xiaoxiao Zeng, Wen Zheng, Weilin Hu, Erjiang Ma, Hongyu Liaoning Key Lab of Advanced Test Technology for Aerospace Propulsion System Shenyang Aerospace University Liaoning Shenyang110136 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shanxi Xi'An710049 China AECC Shenyang Engine Research Institute Shenyang110015 China

The oxidation process in the flow tube reactor at the conditions of P=0.1 MPa, T=500-1850 K, f=0.5, 1.0, 3.5, and the laminar combustion process in the constant volume combustion bomb at the conditions of P=0.1, 0.2, 0.3 MPa, T=300, 350, 400 K, f= 0.7-1.4, the O2 contents of 15%, 18% and 21%, the CO2 and H2O contents of 0%, 10%, and 20% of natural gas (0.9 methane/0.07 ethane/0.03 propane, mole fraction) were experimental tested. In the oxidation process of natural gas, with the equivalence ratio increasing, the starting and ending temperatures for oxidation reaction of natural gas are increased, the reaction temperatures corresponding to CO generation and consumption are higher, and the amount of NO production is decreased. In the the laminar combustion process of natural gas, at the conditions of higher pressure, equivalence ratio, CO2 and H2O contents, the flame front is not smooth as a large number of cracks and cell structures appear, and the flame is unstable. Moreover, with the initial temperature and oxygen content increasing or the initial pressure, CO2 and H2O contents decreasing, the laminar flame speed is increased. Furthermore, combined the path sensitivity analysis, rate of production analysis, reaction path analysis and the decoupling method, a reduced reaction mechanism (including 40 species and 189 reactions) of natural gas was developed. Through comparing with the calculated results by the Aramco 2.0 mechanism and the corresponding test data, the reduced reaction mechanism can well predict the oxidation, ignition delay and laminar combustion characteristics of natural gas under various conditions. © 2023, The Authors. All rights reserved.

关键词： Sensitivity analysis

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Adaptive Growing Randomized Neural Networks for Solving Partial Differential Equations

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arXiv 2024年

作者： Dang, Haoning Wang, Fei Jiang, Song School of Mathematics and Statistics Xi’an Jiaotong University Shaanxi Xi’an710049 China School of Mathematics and Statistics State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Institute of Applied Physics and Computational Mathematics Beijing100088 China

Randomized neural network (RNN) methods have been proposed for solving various partial differential equations (PDEs), demonstrating high accuracy and efficiency. However, initializing the fixed parameters remains a challenging issue. Additionally, RNNs often struggle to solve PDEs with sharp or discontinuous solutions. In this paper, we propose a novel approach called Adaptive Growing Randomized Neural Network (AG-RNN) to address these challenges. First, we establish a parameter initialization strategy based on frequency information to construct the initial RNN. After obtaining a numerical solution from this initial network, we use the residual as an error indicator. Based on the error indicator, we introduce growth strategies that expand the neural network, making it wider and deeper to improve the accuracy of the numerical solution. A key feature of AG-RNN is its adaptive strategy for determining the weights and biases of newly added neurons, enabling the network to expand in both width and depth without requiring additional training. Instead, all weights and biases are generated constructively, significantly enhancing the network’s approximation capabilities compared to conventional randomized neural network methods. In addition, a domain splitting strategy is introduced to handle the case of discontinuous solutions. Extensive numerical experiments are conducted to demonstrate the efficiency and accuracy of this innovative approach. Copyright © 2024, The Authors. All rights reserved.

关键词： Partial differential equations

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Physics-Based Probabilistic Assessment of Creep-Fatigue Failure for Pressurized Components by Extended Direct Steady Cycle Analysis-Driven Neural Network

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SSRN 2022年

作者： Wang, Xiaoxiao Ma, Zhiyuan Yang, Jie Chen, Haofeng Xuan, Fuzhen Department of Mechanical & Aerospace Engineering University of Strathclyde James Weir Building 75 Montrose Street GlasgowG1 1XJ United Kingdom Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China School of Mechanical and Power Engineering East China University of Science and Technology Shanghai200237 China

To achieve a high-reliability design with a feasible balance between accuracy and efficiency, the physics-based probabilistic assessment for creep-fatigue failure is proposed under the probabilistic Linear Matching Method (pLMM) framework. At the physical level, the structural failure mechanism is reflected in the prepared training database, which is generated by the direct method, extended Direct Steady Cycle Analysis (eDSCA) procedures. And to efficiently express the relationship between design parameters and structural responses implicitly, the extended DSCA-driven neural network (EDDNN) is built with the superior fitting quality of damage and lifetime. With the benchmarks of pressurized structures provided, the applicability of the proposed probabilistic analysis approach in solving practical problems is demonstrated, where the reliability-based evaluation diagram is established according to different requirements. Furthermore, a novel data classification scheme is proposed to deal with the randomness in creep damage-dominated probabilistic assessment. © 2022, The Authors. All rights reserved.

关键词： Failure (mechanical)

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