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Evaluation of R513A as an environmentally friendly alternative to R134a in spray cooling for laser surgery: Heat transfer performance and optimization

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International Journal of Thermal Sciences 2025年 215卷

作者： He, Zhi-Zhong Lin, Xiang-Wei Li, Chen-Xi Kong, Chen Shen, Lin-Xin Zhou, Zhi-Fu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China School of Future Technology Xi'an Jiaotong University Shaanxi Xi'an710049 China Xi'an Jiaotong University Health Science Center Shaanxi Xi'an710049 China

Spray cooling plays a pivotal role in mitigating thermal injuries to the epidermis during laser surgery. However, the widespread use of R134a, a refrigerant with a high global warming potential (GWP) of 1300, poses significant environmental concerns. In this study, R513A, a more environmental-friendly cryogen with a GWP of 573, is used to investigate the feasibility of replacing R134a and the effects of spray height, spurt duration, nozzle orifice diameter, and spray pressure on R513A spray cooling through a self-built open-loop spray system. Experimental results demonstrate that R513A exhibits superior cooling performance, achieving a minimum surface temperature (Tmin) 12 °C lower and a maximum heat flux (qmax) 27.5 % higher than R134a. Additionally, R513A offers a broader optimal spray height range (30–50 mm) in which Tmin is 4 °C and 13 °C lower than those at 20 mm and 10 mm, respectively. qmax in this range is 10 % and 16 % higher than those at 20 mm and 10 mm, respectively. While extending the spurt duration consumes more cryogen and prolongs the liquid film lifetime, the differences in Tmin and qmax are less than 4 °C and 10 kW/m2. With the nozzle orifice increasing from 0.6 mm to 1.0 mm, Tmin remains approximately −42 °C but qmax gradually increases by 6 kW/m2. Macroscopic analysis reveals that higher spray pressure induces a more dispersive spray, though this does not significantly improve cooling efficiency. To advance the understanding of R513A spray cooling dynamics, a dimensionless correlation was developed to predict the dynamic heat transfer coefficient across diverse conditions. This study not only highlights the potential of R513A as a sustainable alternative but also provides critical insights into optimizing spray cooling parameters for enhanced thermal management in laser surgery. © 2025 Elsevier Masson SAS

关键词： Chilling

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Particle-Scale Modelling of Injected Hydrogen and Coke Co-Combustion in the Raceway of an Ironmaking Blast Furnace

SSRN

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SSRN 2022年

作者： Dianyu, E. Zhou, Peng Ji, Langyong Cui, Jiaxin Xu, Qiang Guo, Liejin Yu, Aibing International Institute for Innovation Jiangxi University of Science and Technology Ganzhou341000 China Jiangxi Provincial Key Laboratory for Simulation and Modelling of Particulate Systems Jiangxi University of Science and Technology Ganzhou341000 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China ARC Research Hub for Computational Particle Technology Department of Chemical Engineering Monash University VIC3800 Australia Centre for Simulation and Modelling of Particulate Systems Southeast University Monash University Joint Research Institute Suzhou215123 China

Hydrogen is an environmentally friendly fuel that does not produce greenhouse gas (GHG) emissions. Its applications have attracted significant attention from many industries, especially the ironmaking industry, which consumes massive amounts of fossil energy. The injection of hydrogen into a blast furnace (BF) is one of the most promising low-carbon ironmaking routines. In this study, an experimentally validated CFD-DEM model is adopted to investigate the dynamics, microstructure and thermochemical behaviours in the raceway of a BF with hydrogen injection operations (HIOs), which include raceway evolution, force distribution and the co-combustion characteristics of hydrogen and coke. Some significant features are obtained through comparison analyses between HIOs and air injection operations (AIOs). In particular, the effects of the hydrogen injection concentration on the raceway size, gas temperature and components are studied. The simulation results show that a smaller raceway is formed under HIOs in comparison with that of AIOs. In addition, the gas temperature is higher near the tuyere but lower along the tuyere axis, and the oxygen consumption is larger and produces more CO. As the hydrogen injection concentration increases: (i) the raceway size and gas temperature decrease;(ii) the CO is generated at the early stage and the maximum CO2 concentration moves to inlet direction along the tuyere axis. The results provide insights on the fundamental understanding of low-carbon ironmaking BF technology. © 2022, The Authors. All rights reserved.

关键词： Blast furnaces

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Theoretical and experimental analyses of a novel recirculated regenerative rotary desiccant wheel dehumidification system 32

Theoretical and experimental analyses of a novel recirculate...

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32nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2019

作者： Han, Xiaoqu Wu, Wenxiang Zhou, Zhijie Wang, Yu Chong, Daotong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China China Ship Development and Design Center Wuhan China

ISBN: (纸本)9788361506515

The high humidity environment in the submarine cabins results in high energy consumption of the air conditioning system. Moreover, the removal of the hydrogen contained in the air, which constitutes a threat to crew’s safety, generates a huge amount of heat. It is of particular significance to reduce the humidity of the air efficiently, through recovery of the waste heat in the dehydrogenation process. Therefore, a novel recirculated regenerative desiccant wheel dehumidification system is proposed in the present work for submarine air-conditioning. The dehumidification rate was optimized through an appropriate proportion between inlet and recirculating air flows. Theoretical modeling and experimental study were carried out to explore the optimal dehumidification performance at different working conditions. The influence of process air parameters (including temperature and humidity), regeneration air parameters (including bypass ratio and regeneration air temperature) and rotary desiccant wheel parameters (including rotation speed and air flow ratio) were analyzed. It was found that the dehumidification rate could be effectively improved compared to sea water direct cooling. It increased with increasing regeneration air temperature and temperature drop. There was an optimal bypass ratio for the system, around 55%-70%, to obtain the highest dehumidification rate. The ratio increased with the regeneration air temperature. There existed an optimal rotary speed (approx. 12 r·h-1) and optimal air flow ratio (approx. 70%). Overall, the feasibility of the proposed system was validated and the dehumidification characteristics at various working conditions were demonstrated to prompt its application. © ECOS 2019 - Proceedings of the 32nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. All rights reserved.

关键词： Air conditioning

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Study on the gasification mechanisms of key intermediates of oily sludge in supercritical water by ReaxFF-MD method

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Energy 2025年 330卷

作者： Linhu Li Pai Peng Gaoyun Wang Xujun Li Wen Cao Zhengjun Gong School of Environmental Science and Engineering Southwest Jiaotong University Chengdu 611756 China State Grid Jiangsu Electric Power Co. Ltd. Research Institute Nanjing 211103 China Technical Inspection Center Sinopec Shengli Oilfield Company Dongying 257000 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Supercritical water gasification has been confirmed as an advanced treatment method for organic waste including oily sludge. As a supplement to our previous studies, molecular dynamics (MD) simulations must be implemented to understand the gasification mechanism thoroughly. Five representative model compounds were selected to investigate the gasification mechanism using ReaxFF-MD method. The molecular evolution of five key intermediates in SCWG was simulated and compared at 3500 K. To overcome the gasification challenge of oily sludge, toluene was selected for further investigation due to its prominent proportion and relatively low reactivity. Simulations were systematically discussed under different temperatures (2500–3500 K) to study the product distribution. It was found that the yields of the main products (H 2 , CO and CO 2 ) continuously increased with reaction time and temperature. The yields of C1-C3, C4-C7 and C7+ increased more rapidly at higher temperature, with the yield of short-chain carbonaceous organics (C1-C3) being significantly higher than that of other carbonaceous organics. The decomposition kinetics of toluene in supercritical water were also analyzed, and the apparent activation energy was 235.22 ± 22.66 kJ⋅mol −1 . Furthermore, four main gasification pathways were identified by tracking molecular animations. This study would provide valuable insights into the transformation characteristics of oily sludge.

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Thermal Simulation for a Mechanical Spindle With External Cooler Across Grease Coated Interface

Research Square

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Research Square 2021年

作者： Zhao, Liang Lei, Mohan Ren, Hongdi Wang, Jinshi Wang, Shuai Li, Ben Q. Yang, Jun Mei, Xuesong Xi'an Jiaotong University China State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong University Xi'An710049 China Shaanxi Key Laboratory of Intelligent Robots Xi'an Jiaotong University Xi'An710049 China School of Mechanical and Precision Instrument Engineering Xi'an University of Technology 710048 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Mechanical Engineering College of Engineering and Computer Science University of Michigan MI48128 United States

Spindles in precision boring machine often work in low speed and heavy load without internal cooling, and the thermal error is nonnegligible. So an external cooling system was designed, and the effectiveness of the designed scheme needs to be preliminarily verified by simulation before building the cooling system. Thermal simulations of the spindle with an external cooler require calculating the thermal resistance of the thermal grease-coated interface between the cooler and spindle. Models describing the contact thermal resistance and total thermal resistance for metal contact filled with silicone grease based on solid-liquid interface force equivalence were described in this paper, and experiments were also conducted to verify the accuracy of these models. The contact thermal resistances between the cast iron/copper and silicone grease on flat or arc surfaces were calculated, and the bulk thermal resistance of the silicone grease layer was calculated. The total heat transferred between the cooler and the silicone grease-coated interface of the spindle were calculated. Heat transfer and heat generation in the spindle were calculated, and a finite element model was established to verify the effectiveness of the designed external cooling scheme. Finally, results from experiments for the spindle in different conditions show that the external cooling system decreases the time to reach thermal equilibrium by more than 60%. The RMSE of the simulated thermal elongation is less than 5.7044 μm when the rotating speed of 3000 rpm, and is less than 3.9714 μm when the rotating speed is 1500 rpm. © 2021, CC BY.

关键词： Cooling

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Performance of cone meter for measuring cryogenic fluid considering cavitation

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International Journal of Fluid Machinery and Systems 2019年第1期12卷 12-21页

作者： He, Denghui Chang, Zhuang Bai, Bofeng Chen, Senlin Guo, Pengcheng State Key Laboratory of Eco-hydraulic in Northwest Arid Region Xi’an University of Technology NO.5 South Jinhua Road Xi’an710048 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an710049 China

The performance of the cone meter when measuring the cryogenic fluid was investigated by numerical simulation. The results show that the discharge coefficient and pressure loss coefficient of the cone meter are almost constant when the Reynolds number in the "stable region". The cryogenic fluids, especially the liquid hydrogen, have wider stable Reynolds number ranges than the water. There is little effect of cavitation on the discharge coefficient and pressure loss coefficient at the initial stage of cavitation. Thus the effect of slight cavitation on the measurement error of the flow rate is small, whose relative error is less than ±0.5% in present cases. This study opens a new avenue for measuring the flow rate of the cryogenic fluid. © 2019, Turbomachinery Society of Japan. All rights reserved.

关键词： Cavitation

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Numerical simulation of high temperature gas cooled reactors on less of coolant accident 18

Numerical simulation of high temperature gas cooled reactors...

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18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019

作者： Zhang, Shuangbao Li, Liangxing Xie, Wei Wang, Kailin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xianning West Road 28# Xi’an city710049 China

The high temperature gas-cooled reactor (HTR) is well known for its prominent inherent safety, high efficiency and low carbon environmental protection, which has been identified as one of the candidates for the Generation IV nuclear energy system technology. Accurate and reliable thermal hydraulic analysis is of great significance to the system design and safe operation of HTR. Based on the coolant flow and heat transfer process in the core of HTR, this study establishes a three-dimensional model by using CFD (Computational Fluid Dynamics) software firstly, and the flow and heat transfer process of helium coolant is simulate in the core. The temperature distribution of HTR is calculated at steady state, and the calculation results were compared with the related published results for validation and verification. After that, the models are employed to study the thermal hydraulic characteristics under the loss of coolant accident of HTR. The results show that as the coolant passes through the core from top to bottom, helium is continuously heated, and the temperature increases from top to bottom. The temperature reached a maximum at the core exit position of 1032.75 K. It stated that the model can be employed to simulate the thermal hydraulic analysis for HTR. The calculation results of the loss-of-coolant, indicates t as the flow rate decreases, the coolant temperature rises gradually. When the coolant is completely lost, the temperature reaches a maximum of 1723.19 K, and it is still lower than the design limit of 1893.15 K. © 2019 American Nuclear Society. All rights reserved.

关键词： Coolants

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On-Line Measurement of Ultralow Mass Concentration Particulate Based on Light Scattering Coupled with Beta Ray Attenuation Method

SSRN

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SSRN 2022年

作者： Liu, Xiaowei Huang, Yubo Wang, Zhaofeng Jiang, Meng Zhou, Zijian Xu, Minghou Han, Jinke Yang, Bin Fan, Xinfeng State Key Laboratory of Coal Combustion School of Energy and Power Engineering Huazhong University of Science and Technology 1037 Luoyu Road Wuhan430074 China JXIC Energy Technology Research Institure Nanchang330000 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Wuhan Tianhong Environmental Protection Industry Co. Ltd Yuhong Environmental Protection Science and Technology Industrial Park No.11 Huashiyuan North Road Miaoshan District Donghu high tech Development Zone Wuhan430074 China

Light scattering method is the most commonly used method for on-line measurement of ultralow particulate matter mass concentration. However, when the particle characteristics change, the effectiveness of the empirical relationship decreases, which would lead to a sizeable deviation. To accurately measure the mass concentration of particulate matter in real-time, a coupling measurement idea of light scattering and beta-ray attenuation is proposed. The beta-ray attenuation is little affected by particle properties and accurately reflects the average PM mass concentration in the measured period. The single calibration method (M1), periodic calibration method (M2), average calibration method (M3), and asymmetric factor calibration method (M4) are formed based on the coupling idea. The results of all methods are perfect when the particle size is unchanged. However, when the particle sizes fluctuate frequently, the results of M1, M2, and M3 deviate seriously from the actual value, and the applicable working conditions have limitations. The results of M4 are in good agreement with the actual value, and the effectiveness is not limited by the particle size. Finally, the prototype based on experimental exploration was developed and had been continuously operated for more than 528 hours at a 1000 MW unit of a coal-fired power plant. © 2022, The Authors. All rights reserved.

关键词： Particle size

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Modeling study on anisotropic heat conduction of PEMFC GDLs facilitated by Micro-CT

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International Journal of Heat and Mass Transfer 2025年 250卷

作者： Hang Liu Xuecheng Lv Heng Huang Yang Li Deqi Li Zhifu Zhou Wei-Tao Wu Lei Wei Yubai Li Yongchen Song Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian 116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing 210094 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen 518055 China

The gas diffusion layer (GDL) serves as a pivotal component governing heat transfer in proton exchange membrane fuel cells (PEMFCs). Excessive heat accumulation within the catalyst layer may lead to irreversible degradation of electrochemical activity due to accelerated catalyst sintering and carbon support corrosion. Building upon multi-modal characterization integrating micro-computed tomography (Micro-CT) and scanning electron microscopy (SEM) of GDLs, this investigation systematically deciphers the interdependent relationships between fiber architecture, sphere network topology, and compression-mediated morphological evolution through advanced computational analytics and finite element modeling. The quantified synergy elucidates microstructure-property linkages governing anisotropic thermal and gas transport phenomena. The computational findings reveal pronounced anisotropic thermal conduction characteristics within GDLs, demonstrating significantly inferior thermal transport capabilities in the through-plane (TP) direction compared to the in-plane (IP) direction. Reduced fiber length diminishes multi-directional heat dissipation, whereas GDL thickening enhances multi-directional thermal transport efficiency. Quantitative analysis demonstrates a 23-fold higher susceptibility of effective thermal conductivity (ETC) to compression ratio compared to thickness variation, conclusively establishing microstructural heterogeneity as the primary determinant of anisotropic thermal transport. Spatially resolved thermal flux mapping reveals strong geometric coupling with porosity gradients. These multiscale findings provide new design paradigms for optimizing GDL architectures through targeted manipulation of fiber-sphere coupling mechanics.

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The theoretical and numerical analysis on a multi-blade liquid lead pump 27

The theoretical and numerical analysis on a multi-blade liqu...

引用

27th International Conference on Nuclear engineering: Nuclear power Saves the World!, ICONE 2019

作者： Wang, Kailin Li, Liangxing Xie, Wei Zhang, Shuangbao State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xianning West Road 28# Xi'an city710049 China

ISBN: (纸本)9784888983051

Lead or lead-alloy cooled fast reactors (LFRs) have been proved to be the most promising Generation IV reactors with high performance in neutronics, thermal hydraulics and security features. Small forced circulation modular LFRs is one of the potential candidates for LFRs development which has attracted particular attention in recent years. When lead-bismuth eutectic (LBE) is used as coolant, the primary LBE pump is a key conveying equipment, and therefore the hydraulic performance of LBE pump is great important to the safety of LFR. Motivated by improving the hydraulics performance of LBE pump, this paper presents a theoretical and computational analysis on an axial flow pump. The guide blades are set at the outlet of the impeller to eliminate the rotational motion of the liquid LBE and transform the kinetic energy of the rotational motion into pressure energy. The rotation angle of the blade is optimized based on the theoretical analysis to reduce the vortex and raise efficiency. As well, the outlet speed and pressure parameters of each part in the pump are calculated. After that, a three-dimensional model of the modified pump is established by using CFD software and the flow characteristics of LBE in the pump are simulated. Albeit the high velocity liquid LBE alloy still exists in the side of pump shroud, some erosion-related issues remain to be fully addressed. The results of the study show that the axial LBE pump could be used as a viable solution for the design of the new generation of small module reactor primary pump from a thermo-fluid dynamic point of view. © 2018-2019 by JSME

关键词： Pumps

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