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Curvature-property coupling governed heat transfer deterioration in supercritical helically coiled tubes: Mechanistic insights and mitigation strategies via structural parametrization

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International Journal of Thermal Sciences 2025年 215卷

作者： Chang, Fucheng Xin, Jiaxing Wu, Xiaoyi Li, Liwei Li, Huixiong Zhu, Yanlin National Key Lab of Aerospace Power System and Plasma Technology School of Mechanical Engineering Xi'an Jiaotong University Xi'an710049 China China Special Equipment Testing and Research Institute Beijing100029 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China Shanghai Nuclear Engineering Research & Design Institute Co. Ltd Shanghai200233 China

The unique thermo-hydrodynamic coupling phenomena in the helically coiled tube (HCT) handling supercritical fluids present both opportunities and challenges for next-generation compact heat exchangers. While the pronounced thermophysical property variations near pseudo-critical temperatures (Tpc) and curvature-induced secondary flows synergistically enhance heat transfer coefficient (HTC), their nonlinear coupling mechanisms may unexpectedly provoke severe heat transfer deterioration (HTD). Through systematic numerical investigations, this study reveals that circumferential wall temperature inhomogeneity (CWTI) exhibits an inverted N-shaped evolution, providing valuable insights for thermal homogenization design near Tpc. The secondary flow Reynolds number (Se), quantifying secondary flow intensity, shows a monotonic increase with decreasing coil diameter (Dc) or inner diameter (Di), reaching saturation in high-enthalpy regions. Notably, CWTI demonstrates non-monotonic behavior, achieving minimum values near Tpc before manifesting distinct rebound characteristics near Tpc conditions. Parametric analysis establishes that: (1) Elevating heat flux (q) increases Se, reducing Dc boosts it by 50.3 %, and decreasing Di raises it by 60.0 %. (2) HTD predominantly initiates at the outer wall under high-q conditions, with Dc reduction achieving HTD suppression and 26.9 % enhancement in the local HTC;(3) Reducing the Di results in a reduction of maximum CWTI by 22.5 %–28.6 %, suggesting that structural parametrization effectively mitigates wall temperature non-uniformity, thus suppressing the HTD. While centered on supercritical water, the dimensionless scaling relationships demonstrate extendibility to other media, with the curvature-property coupling mechanism both elucidating fundamental interactions and guiding robust heat exchanger design. © 2025 Elsevier Masson SAS

关键词： Electric heating

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Experimental Study of Air-Steam–Mixture Condensation Underneath Containment Vessel Surface

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Nuclear Science and Engineering 2021年第8期195卷 838-852页

作者： Bing Tan W. X. Tian R. H. Chen S. Z. Qiu G. H. Su a Xi’an Jiaotong University School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering 28 Xianning West Road Xi’an 710049 Chinab South China University of Technology School of Electric Power Guangzhou 510640 China a Xi’an Jiaotong University School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering 28 Xianning West Road Xi’an 710049 China

Aiming at studying the condensate flow phenomenon and air-steam–mixture condensation heat transfer underneath a containment vessel surface, a test bench was constructed. The plate dimension was 1.5 × 0.6 m, with Carbozinc 11 coating on the surface, suspended in a pressure vessel with 2.5-m diameter and 4.5-m height. The air-steam mixture was condensed on an inclined plate through natural convection mode and jet mode. By observing flow behavior on the plate through a viewport, four basic regimes were obtained as the inclination angle gradually increased: droplet, droplet to rivulet transition, developed rivulet, and uniform film. During the experiment, we observed a steam atomization phenomenon; therefore, the model predicted better with the atomization effect considered. A simple formula from the condensation data is proposed when the air mole fraction is small. The error between the experimental results and the predicted data is within 25%.

关键词： Passive cooling system steam condensation flow regime new empirical correlation

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High-Entropy (Cocrfemnni)3o4 Catalysts for Propane Catalytic Destruction: Effect of the Precipitation Agent

SSRN

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SSRN 2023年

作者： Ma, Yue Zhang, Yun Jian, Yanfei Jiang, Zeyu Chai, Shouning Li, Lu Xia, Lianghui He, Chi State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Department of Physics and Information Technology Baoji University of Arts and Sciences Shaanxi Baoji721016 China National Engineering Laboratory for VOCs Pollution Control Material & Technology University of Chinese Academy of Sciences Beijing101408 China

Efficient catalytic destruction of light alkane with ultra-stable and highly symmetric structure is still an intractable issue. High entropy oxides (HEOs) with high chemical disorder and lattice distortion and superior stability have shown great potential in heterogeneous thermocatalysis. Herein, spinel-type HEOs are synthesized via a scalable co-precipitation method with different precipitants (NaOH, Na2CO3, and NaHCO3) and firstly adopted in catalytic destruction of propane. Results demonstrate that the HEO-NaOH possesses the best activity, achieving 90% of propane conversion at 325 °C with an apparent activation energy of 56 kJ·mol-1. Compared with other two HEOs, HEO-NaOH system has larger quantities of surface oxygen vacancies and easily forming several reactive oxygen species (OOH-, O2-, and OH-, etc.), which significantly contribute to the catalytic performance. Moreover, the excellent water resistance of HEOs is verified due to their high conformational entropy and structural stability. Reaction mechanism reveals that OOH- and O2- are the key species in the oxidation of C3H8, which break C-H and C-C bonds in sequence, and are then converted to oxygenated compounds via oxygen oxidation before the final mineralization. The present work provides new insights into the fabrication of efficient catalysts for light alkane destruction as well as other thermocatalytic applications. © 2023, The Authors. All rights reserved.

关键词： Sodium hydroxide

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

SSRN

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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

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Theoretical Study on Photoacoustic Tweezers Based on Photo-Thermo-Acoustic-Mechanical Coupling Effects

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Zhongguo Jiguang/Chinese Journal of Lasers 2025年第9期52卷

作者： Lin, Zhanle Hu, Feifan Shan, Wanru Li, Dong Chen, Bin Zheng, Yuping Yao, Liang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Department of Ophthalmology The Second Affiliated Hospital Xi’an Jiaotong University Shaanxi Xi’an710004 China

Objective Photoacoustic tweezers (PATs) are a promising noninvasive technology for precise microparticle manipulation that leverage the photoacoustic effect to exert controlled forces on particles within a liquid medium. Conventional methods, such as optical and acoustic tweezers, present limitations such as potential damage to particles, inadequate spatial control, and restricted manipulation in three-dimensional (3D) environments. Hence, this study focuses on the theoretical development of a PAT model that integrates photo-thermo-acoustic-mechanical coupling effects. Using a ring-shaped laser beam, this study aims to investigate particle motion and force characteristics under various laser conditions. Additionally, this study seeks to establish a robust theoretical framework for PATs, thus filling the gaps in 3D particle manipulation and providing guidance for the optimization of experimental parameters. Methods A multiphysics coupling model for PATs was constructed to describe the interactions among photo-thermal, acoustic, and mechanical effects in a liquid medium. The model accounts for the transformation of laser energy density into heat and the subsequent thermal expansion, and the generation of acoustic waves that induces acoustic radiation forces and acoustic streaming. A ring-shaped laser beam was employed to create spatially confined acoustic fields that can trap and manipulate particles. Using the finite-element method (FEM) in Comsol software, the model was used to simulate high-frequency pulsed laser effects, including energy transfer, thermal expansion, acoustic wave propagation, and the resultant particle dynamics. The governing equations for the coupled fields were derived by incorporating the spatial and temporal distributions of the laser, the thermal and acoustic properties of the medium, and force interactions on the particles. The acoustic radiation forces were modeled based on Gor’kov potential theory, whereas the acoustic streaming fields wer

关键词： Acoustic emissions

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pH-Triggered Hydroxylated Surface with Rapid Hydroxyl Radical Generation Boosts Efficient Noble-Metal-Free Pilot-Scale Photoreforming of Lignocellulose for Hydrogen Production

SSRN

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SSRN 2023年

作者： Liu, Feng Fu, Yiwei Lu, Kejian Wang, Shujian Wang, Biao Huang, Jie Yan, Xueli Zheng, Yiqun Guo, Liejin Liu, Maochang International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi’an710049 China School of Chemistry Chemical Engineering and Materials Jining University Shandong Qufu273155 China Suzhou Academy of Xi’an Jiaotong University Jiangsu Suzhou215123 China

Photocatalytic H2 prodcution from lignocellulosic biomass photoreforming is deemed to be a promising alternative to overall water splitting owing to its more sustainable and value-added oxidation half-reaction. However, an efficient lignocellulose photoreforming system toward H2 production, especially at the pilot scale, is scarce and exigent to date. Herein, we present a lignocellulose photoreforming system containing noble-metal-free particulate twinned Cd0.5Zn0.5S nanocatalyst, water, and lignocellulose, enabling an unprecedented H2 evolution activity with an apparent quantum yield of 12.74% at 400 nm. Subsequently, an outdoor 7.2-m2 compound parabolic concentrator-based reactor is developed to scale up this system to a practical level with a H/2 production rate of 615 mL h-1 under direct solar irradiation. We demonstrate that a pH-triggered hydroxylated surface over Cd0.5Zn0.5S nanotwins enables superior hole transfer and rapid hydroxyl radical generation by inducing favorable reaction kinetics/thermodynamics in alkaline solution. Our work thus provides a state-of-art example of pilot-scale system for the practical Hsub>2 production via lignocellulose photoreforming. © 2023, The Authors. All rights reserved.

关键词： Lignocellulose

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Editorial of special issue (SI) "Multi-scale physics on fluid flow and heat transfer (Multi-scale PFFHT)"

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International Journal of Heat and Fluid flow 2025年 115卷

作者： Cheng, Lixin Bai, Bofeng Zhang, Haibin Wissink, Jan Gerard School of Engineering and Built Environment Sheffield Hallam University City Campus Howard Street SheffieldS11WB United Kingdom State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 China Department of Mechanical and Aerospace Engineering Brunel University of London Kingston Lane UxbridgeUB8 3PH United Kingdom

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Experimental Studies of Liquid Immersion Cooling for 18650 Lithium-Ion Battery Under Different Discharging Conditions

SSRN

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SSRN 2022年

作者： Li, Yang Zhou, Zhifu Hu, Leiming Bai, Minli Gao, Linsong Li, Yulong Liu, Xuanyu 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 Department of Mechanical Engineering Carnegie Mellon University Pittsburgh15213 United States

In this study, the fluorinated liquid immersion cooling as a new cooling scheme has been tested and discussed for cooling the 18650 lithium-ion battery. OpteonTM SF33, with boiling point of 33.4oC, is chosen as the fluid for the immersion cooling. Comparison of the liquid immersion cooling and convective air cooling for a 18650 lithium-ion battery under 2C, 4C and dynamic load conditions are made. It is found that the immersion cooling better cools the battery cell under all these conditions. Under 4C discharging, the maximum cell temperature rise is 14.06°C for the forced air cooling, while is 4.97°C for the liquid immersion cooling. As the cooling fluid’s temperature basically governs the battery cell temperature, the cooling fluid’s temperature should not be too low. This study demonstrates that the lithium-ion battery has non-negligible power losses under cooling liquid temperature of 10oC and 15oC, compared with temperature above 20oC. Lastly, the two-phase boiling heat transfer mechanisms associated with immersion cooling of lithium-ion battery are discussed with bubble dynamics analysis. It is found under higher C rate, more aggressive boiling heat transfer is induced. The battery temperature is controlled to be below 34.5oC even under 7C discharging condition. © 2022, The Authors. All rights reserved.

关键词： Lithium-ion batteries

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Thermodynamic Analysis of a Hybrid Energy System Coupling Solar Organic Rankine Cycle and Ground Source Heat Pump: Exploring Heat Cascade Utilization

SSRN

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SSRN 2023年

作者： Chen, Liangqi Yue, Huifeng Wang, Jiangfeng Lou, Juwei Wang, Shunsen Guo, Yumin Deng, Bohao Sun, Lu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China China United Northwest Institute for Engineering Design & Research Co. Ltd Xi’an710077 China School of Human Settlements and Civil Engineering Xi'an Jiaotong University Xi’an710049 China

The demand for efficient utilization of renewable energy is growing and the hybrid energy system driven by solar and geothermal energy is a significant way to achieve carbon neutrality. This paper presents a hybrid energy system coupling solar organic Rankine cycle (S-ORC) with ground source heat pump (GSHP) for heating and power supply to explore the heat cascade utilization. In the hybrid energy system, the ground heat exchanger (GHE) is shared by the S-ORC and GSHP systems and the waste heat from the condenser of S-ORC is recovered to enhance the coefficient of performance (COP) of GSHP. A mathematical model is optimized to analyze the parametric effects on thermodynamic performance. The results indicate that the COP of the hybrid energy system can be improved up to 6.5 which shows the obvious advantage compared to 2.8 of the stand-alone GSHP system. Furthermore, the hybrid energy system can obtain optimum exergy efficiency by matching ground source temperature and condensation temperature in the ORC unit. For a building of 3000m2 with heating and power supply, multi-objective optimization is carried out to obtain the optimal design performance that the net power output, thermal efficiency and exergy efficiency are 180.0kW, 27.5%, and 9.2% respectively. © 2023, The Authors. All rights reserved.

关键词： Geothermal heat pumps

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

SSRN

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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

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