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A review on thermal application of metal foam

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Science China(Technological Sciences) 2020年第12期63卷 2469-2490页

作者： CHEN Kang GUO LieJin WANG Hui State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China Institute of Solar Engineering Technology Northwest Engineering Corporation LimitedPowerChinaXi’an 710065China School of Environmental Science and Engineering Donghua UniversityShanghai 201620China

Heat exchangers embedded with metal foam are drawing increasing attention in the thermal application field,due to the performance of low density,large ratio of surface area to volume as well as high thermal conductivity. In these applications,compact heat exchanger,solar thermal facilities and thermal energy storage are the three core components. This paper focuses on the lasted advances in thermal applications,presenting a review of theoretical and experimental progress over metal foam in thermal application. The empirical and theoretical models for pressure drop,heat transfer coefficient and performance evaluation criteria of compact heat exchangers with metal foam are reviewed and discussed,especially different optimized *** is a trade-off between heat transfer enhancement and increase of pressure drop. Some exploratory work performed by present authors are also introduced. The manufacturing,heat transfer and flow characteristics of tube bundle wrapped with metal foam are taken into account for optimization of heat exchanger. It is confirmed that the conversion mechanism of heat transfer is carried out that heat conduction is the dominative term at high dimension permeability. The correlations of heat transfer rate and pressure drop for staggered and single row tube bundle wrapped with metal foam are concluded,respectively. The effects of different bonding methods are revealed for point-contact in metal foam and base tube. The powder-sintering method can provide a stable and minimum-thickness bonding layer. Various types of solar thermal facilities utilized metal foam to improve the energy conversion efficiency from solar radiant energy to thermal energy are also reviewed and discussed,including solar collector for intermediate-low temperature utilization and solar receiver for high temperature utilization. The Last but not least,existing and future metal foam thermal application stations are overviewed.

关键词： metal foam heat transfer enhancement solar thermal facilities thermal energy storage

Effect of 2,5-dimethylfuran addition on ignition delay times of n-heptane at high temperatures

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Frontiers in Energy 2019年第3期13卷 464-473页

作者： Zhenhua GAO Erjiang HU Zhaohua XU Geyuan YIN Zuohua HUANG State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

The shock tube autoignition of 2,5-dimethylfuran (DMF)/n-heptane blends (DMF)/n-1.0%, by mole fraction) with equivalence ratios of 0.5, 1.0, and 2.0 over the temperature range of 1.00-1.00 K and pressures of 2.0 atm and 1..0 atm were investigated. A detailed blend chemical kinetic model resulting from the merging of validated kinetic models for the components of the fuel blends was developed. The experimental observations indicate that the ignition delay times nonlinearly increase with an increase in the DMF addition level. Chemical kinetic analysis including radical pool analysis and flux analysis were conducted to explain the DMF addition effects. The kinetic analysis shows that at lower DMF blending levels, the two fuels have negligible impacts on the consumption pathways of each *** the DMF addition increases to relatively higher levels, the consumption path of n-heptane is significantly changed due to the competition of small radicals, which primarily leads to the nonlinear increase in the ignition delay times of DMF/n-heptane blends.

关键词： ignition delay time shock tube kinetic model 2,5-dimethylfuran (DMF) n-heptane

Thermal-Hydraulic Characteristics of Helical Cruciform Single Rod Based on Cfd Investigation

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SSRN 2024年

作者： Chen, Yiwen Zhang, Dalin Jiang, Dianqiang Deng, Jian Zhang, Xisi Wang, Xinan Tian, Wenxi Qiu, Suizheng Su, Guanghui 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 Nuclear Power Institute of China 328 Changshun Avenue Chengdu610213 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China China Institute of Atomic Energy Beijing611731 China

To increase power density in nuclear reactors, the helical cruciform fuel (HCF) is designed as a fundamental element. HCF takes advantages of strong mixing effects, self-supporting features, and strengthened heat transfer, potential to increase the fuel performance in nuclear reactors. In this paper, friction factor and heat transfer coefficient empirical correlations of HCF single rod cooled by water were proposed using a geometric dimensionless number based on numerical simulation. The velocity field, and temperature distribution were obtained to discuss influences of geometric sizes on the fuel performance. Finally, correlations with a geometric dimensionless number were validated with various cases, whose application conditions were also proposed and discussed. This paper provides a guide for study of heat transfer and fluid {1. in helical structures, and a reference for establishment of reactor system model using helical cruciform fuels. © 2024, The Authors. All rights reserved.

关键词： Heat transfer coefficients

Comparative Analysis on Energy Losses in Hydrogen and Helium Turbo-Expanders for Hydrogen Liquefiers

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SSRN 2022年

作者： Zhou, Kaimiao Chen, Liang Li, Shanfeng Zhao, Kang Zhang, Ze Chen, Shuangtao Hou, Yu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Beijing institute of Aerospace Testing Technology Beijing100074 China

The helium Brayton cycle and the hydrogen Claude cycle are the baseline processes for large-scale hydrogen liquefaction. Helium and hydrogen turbo-expanders are the crucial components, respectively, determining the system efficiency and reliability. In this paper, a comparative analysis is performed on the energy losses in helium and hydrogen turbo-expanders for hydrogen liquefaction systems. Similarity analysis is carried out to set the baseline design of helium and hydrogen turbo-expanders. Mean-line method is employed in the design, and losses in nozzle and impeller are determined. CFD simulations are performed to illustrate the internal flow field and loss mechanisms in helium and hydrogen turbo-expanders. The CFD predictions of isotropic efficiency agree well with that by the loss models. The results show that the passage loss in the impeller is the dominant loss for cryogenic hydrogen and helium turbo-expanders. Due to the higher sound speed and lower viscosity, the hydrogen turbo-expander has smaller nozzle loss and incidence loss compared with the helium turbo-expander, but the tip clearance loss and residual velocity loss in the hydrogen expander are larger. © 2022, The Authors. All rights reserved.

关键词： Helium

Study on the Flame Structure and flow Field of Hydrogen-Enriched Combustion in Array Micro-Tube

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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 {1. 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 1.0.6 mm3. Upon coupling the flame with the {1. field, it was discovered that the exit {1. 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

Propagation and Burning Velocity of Iron-Methane-Oxygen-Nitrogen Turbulent Expanding Flames

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SSRN 2023年

作者： Cai, Xiao Su, Limin Su, Shouguo Wang, Jinhua Alden, Marcus Li, Zhongshan Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Division of Combustion Physics Lund University P.O. Box 118 LundS221 00 Sweden

The propagation and burning velocity of iron-methane-oxygen-nitrogen turbulent expanding flames were experimentally studied by employing a newly optimized spark-ignition, fan-stirred combustion chamber, in which micron-sized iron particles can be dispersed homogeneously. Fine iron particles with averaged diameter of 1.9 μm was used in the present study. The flame trajectory of iron-methane mixture at different turbulence intensities and iron concentrations was recorded using a high-speed camera. It was found that the flame propagation speed increases as iron-methane turbulent flame expands. The acceleration process is mainly caused by the extension of flame surface dissipation spectrum by increasing the largest flame scales (flame radius). The turbulent burning velocity, ST increases significantly with the turbulence intensity, which is well known feature in gaseous flames. However, the iron concentration does not have an obvious effect on the ST, which is unique to iron flame in turbulence environment. Because the turbulent flame propagation is dominated by turbulent heat transfer, which is characterized by turbulence intensity. In addition, the formation of iron flame front is controlled by the couple effects of iron concentration and turbulence intensity in turbulent environment. Furthermore, the laminar burning velocity, SL was accurately determined using a nonlinear extraction method. A correlation of turbulent burning velocity was obtained based on the experimental iron-methane data. The measured ST and its correlation would be used to develop practical iron burners and to validate turbulent combustion models of iron flames. © 2023, The Authors. All rights reserved.

关键词： Iron

Thermal Management for the 1.650 Lithium-Ion Battery Pack by Immersion Cooling with Fluorinated Liquid

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SSRN 2023年

作者： Li, Yang Bai, Minli Zhou, Zhifu Wu, Wei-Tao Hu, Chengzhi Gao, Linsong Liu, Xinyu 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

In this work, a new battery thermal management system (BTMS) utilizing a SF33-based liquid immersion cooling (LIC) scheme has been proposed. Firstly, the comparative investigation focuses on the temperature response of the LIC and forced air cooling (FAC) modules in different scenarios. The results demonstrate that LIC module effectively mitigates heat accumulation, thereby presenting notable advantages in terms of temperature control and equalization, even though the LIC module works under the stage without phase change occurrence. During 2C and 3C charging, the highest temperatures of the LIC module are observed to be 1. °C and 1..1.°C only lower than those of the FAC module, respectively. Furthermore, the highest temperature differences of the LIC module are only 1..89% and 8.57% of the corresponding values exhibited by the FAC module. Moreover, the associated cooling energy consumption for the LIC module is greatly reduced, amounting to only 1..47% and 43.76% of that required by the FAC module. Subsequently, an active control scheme for the LIC is initially proposed, and the phase change process of the LIC under various discharging rates is recorded and analyzed using a high-speed camera. This study serves as a preliminary proof of concept for the feasibility of SF33-based LIC scheme in BTMS. © 2023, The Authors. All rights reserved.

关键词： Lithium-ion batteries

Parametric Investigation of Multi-Pulsed Cryogen Spray Cooling for Skin Protection During Hyperthermal Laser Lipolysis Through in Vitro Experiment and Numerical Simulation

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SSRN 2022年

作者： Xin, Hui Yu, Fangbo Deng, Chenggang Chen, Ming Li, Dong Chen, Bin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi'An710049 China School of Mechanical Engineering Ningxia University Ningxia Yinchuan750021 China

Laser lipolysis is now a commonly accepted modality to remove fat. Transcutaneous hyperthermal laser lipolysis has attracted researchers’ interest because of its advantages of non-invasive nature and high efficiency. Owing to the competitional absorption of laser energy between skin and adipose tissue, it is necessary to develop efficient skin cooling technology to protect epidermis and dermis from thermal damage. In vitro laser experiment was carried out using streaky pork which has similar optical and thermal properties with human adipose tissue. Temperature changes of pigskin epidermis under 1.1.nm laser irradiation with different power (6W~1.W) and irradiation duration (3s~1.s) were obtained by infrared thermal imager. The experimental results showed that the epidermis temperature will exceed the safety threshold of 47°C when laser power is equal to 6W and irradiation duration longer than 5s, or laser power is equal or larger than 9W and irradiation duration equal or longer than 3s. To protect skin from thermal injury, multi-pulsed cryogen spraying cooling (MP-CSC) by using R1.4a was introduced. Numerical simulation was conducted to match cooling and laser parameters by simplifying skin tissue to a multi-layered model. It is suggested that hyperthermal laser lipolysis with power of 6W/9W and irradiation duration of 7s can be realized, accompanied by MP-CSC with pulse duration of 1.ms, pulse delay of 2000ms and pulse number of 5. © 2022, The Authors. All rights reserved.

关键词： Cooling

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 1. 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