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Numerical Investigation of the Thermal Response to Skin Tissue during Laser Lipolysis

Journal of Thermal Science 2018年第5期27卷 470-478页

作者： CHEN Bin ZHANG Yue LI Dong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

Laser lipolysis can effectively treat obesity and its associated diseases, such as hypertension, fatty liver, and hyperlipidemia. However, currently available invasive laser lipolysis, which transmits laser to a fiber-optic catheter inserted into the subcutaneous tissue for irradiation through an incision, may cause hematomas, infections, and empyrosis. The current study presents a novel, noninvasive approach for laser lipolysis, which directly irradiates the intact skin surface without an incision and preferentially targets adipose tissue at the near-infrared band. High laser energy is necessary to damage adipocytes; however, this may carbonate and burn the dermis. Therefore, the introduction of skin cooling is essential to avoid unwanted hyperthermal injury and improve the threshold of radiant exposure. In the current study, we investigated a novel noninvasive approach assisted with skin cooling by establishing a homogeneous multi-layer skin model. In this method, light propagation in the skin was simulated by using the Monte Carlo method. Skin cooling was employed before laser irradiation to protect the epidermis from thermal damage, which was treated as a boundary condition based on Newton's law. The numerical results showed that the photons were deposited in the adipose layer more than in the other layers. Laser can effectively destroy adipose tissue at an energy density of >200 J/cm^2 at 1210 nm wavelength, whereas at least 300 J/cm^2 is required at 1064 nm to achieve the same effect. In this experiment, at >5 s pulse width, the selectivity of adipose was not obvious. Moreover, the results indicated that 60 ms R134a or R404a spray can effectively reduce the temperature of the epidermis. R404a exhibited a stronger cooling effect than R134a. Cold air cooling at -10 °C for 10 s could effectively decrease the skin temperature, and deeper cooling could be achieved by cold air cooling compared with cryogen spray cooling.

关键词： laser lipolysis Nd：YAG laser multi-layer skin model skin cooling

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Simulation study of channel structural design for direct internal reforming methane solid oxide fuel cell

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Applied Thermal engineering 2025年 274卷

作者： Wu, Wenzhao Bi, Xiaobing Lv, Xuecheng Li, Yang Zhou, Zhifu Wu, Wei-Tao Wei, Lei Lyu, Jizu 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

Reasonable designs on channels could effectively improve cell performance. This study established a 3D model of planar solid oxide fuel cell directly fueled by methane to investigate the impacts of three independently designed channel structures. This includes modifications to the channel cross-sectional shape (trapezoid and bow), inserting petal-shaped obstacles (single-layer and double-layer), and the study of deflector sheets embedded into the anode channel to address the highly endothermic nature of the methane steam reforming reaction. The research results indicated that, whether trapezoidal or bowed cross-sections are used, the current density achieves the largest growth rate at L_a = 1.5W_CH (16.06 % for bow and 15.53 % for trapezoid). Additionally, double-layer obstacles provide a greater enhancement of current density than single-layer obstacles (11 % for single-layer, 18 % for double-layer) and result in smaller and more uniform fuel flow velocity distribution in the channel. Embedding two or three deflector sheets into the anode channel significantly reduces the maximum temperature difference (by 7 K for two sheets;by 10 K for three sheets, representing a nearly 48 % reduction) and notably improves the temperature distribution uniformity. The study provides a novel perspective on channels alteration which could contribute to the advancement of researches on high-efficiency SOFCs. © 2025 Elsevier Ltd

关键词： Deflection (structures)

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A 3D-dimensional interconnected structured poly (m-phenylene isophthalamide) nanofiber separator with Li1.5Al0.5Ge1.5(PO4)3 for high-safety lithium-sulfur batteries

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Journal of power Sources 2025年 645卷

作者： Liu, Jianwei Zhu, Lei Chai, Qinqin Sun, Shiyi Yang, Xiaomeng Sun, Jingyun Zhang, Yating Zhu, Youyu Yan, Wei College of Chemistry and Chemical Engineering Xi'an University of Science and Technology Shaanxi Xi'an710054 China Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiao tong University Shaanxi Xi'an710049 China Xi'an Hantang Analysis & Test Co. Ltd Shaanxi Xi'an710201 China

Safety concerns have consistently presented substantial obstacles to the widespread adoption of lithium-sulfur (Li-S) batteries. Conventional polyolefin separators, which are characterized by low flash points and insufficient mechanical strength, pose potential safety hazards, including risks of fire and explosion under extreme operating conditions. In this study, we introduce a thermally stable and non-flammable poly-m-phenyleneisophthalamide (PMIA)-based multifunctional separator (L-PMIA separator), which is enhanced with lithium aluminum germanium phosphate (Li1.5Al0.5Ge1.5(PO4)3 or LAGP) fillers. By incorporating g high-ionic-conductivity LAGP and establishing an interconnected framework, this design effectively mitigates the issues of particle agglomeration and uneven commonly ion transport associated with traditional separators. The L-PMIA separator demonstrates remarkable mechanical strength (with a tensile strength of 8.5 MPa and a puncture force of 0.72 N) and thermal stability (showing no dimensional shrinkage even at 200 °C), while also facilitating the formation of continuous ion channels that inhibit lithium dendrite growth. Consequently, Li-S batteries utilizing the 4L-PMIA separator demonstrated a reversible capacity of 4.97 mAh cm−2 after 150 cycles, even under conditions of high sulfur loading (6.75 mg cm−2), limited electrolyte availability (E/S = 7), and elevated temperatures. This approach offers novel insights for the development of future energy storage systems characterized by enhanced safety and performance. © 2025 Elsevier B.V.

关键词： Lithium sulfur batteries

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Experimental Investigation on Heat Transfer Characteristics of Water in Inclined Downward Tube of a Supercritical Pressure CFB Boiler

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Journal of Thermal Science 2015年第5期24卷 478-487页

作者： WANG Siyang YANG Dong XIE Beibei WANG Long WANG Yongjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University

In this study, experiments have been performed for an investigation on heat transfer of water in an inclined downward tube with an inner diameter of 20 mm and an inclined angle of 45° from the horizon, with the range of pressure from 11.5 to 28 MPa, mass flux from 450 to 1550 kg/(m2 s), and heat flux from 50 to 585 k W/m2. Based on the experimental data, the temperature distribution in the tube wall was derived. The heat transfer characteristics of inclined downward flow were compared with that of vertical downward flow. The effects of heat flux on wall temperature were analyzed and the corresponding empirical correlations were presented. The results show that heat transfer characteristics of water in the inclined downward tube are not uniform along the circumference from the top surface to the bottom surface. An increase in heat flux exacerbates the non-uniformity. At subcritical pressures, both dry-out and departure from nucleate boiling(DNB) occur at the top surface of the inclined downward tube; inversely, only dry-out takes place on the bottom surface of the inclined downward tube and in the vertical downward tube. At near-critical pressures, DNB and dry-out occur in the comparing tubes with greater possibility. At supercritical pressures, heat transfer gets enhanced in the pseudo-critical enthalpy region; in the high enthalpy region, the top surface temperature of the inclined downward tube decreases obviously.

关键词： inclined downward tube wall temperature circumferential non-uniformity heat transfer deterioration

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Industrialization prospects for hydrogen production by coal gasification in supercritical water and novel thermodynamic cycle power generation system with no pollution emission

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Science China(Technological Sciences) 2015年第12期58卷 1989-2002页

作者： GUO LieJin JIN Hui GE ZhiWei LU YouJun CAO ChangQing State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

Energy conversion and utilization, particularly carbon-based fuel burning in air phase, have caused great environmental pollution and serious problems to society. The reactions in water phase may have the potential to realize clean and efficient energy conversion and utilization. Coal gasification in supercritical water is a typical carbon-based fuel conversion process in water phase, and it takes the advantages of the unique chemical and physical properties of supercritical water to convert organic matter in coal to H2 and CO2. N, S, P, Hg and other elements are deposited as inorganic salts to avoid pollution emission. The state key laboratory of multiphase flow in power engineering has obtained extensive experimental and theoretical results based on coal gasification in supercritical water. Supercritical water fluidized bed reactor was developed for coal gasification and seven kinds of typical feedstock were selected. The hydrogen yield covers from 0.67 to 1.74 Nm3/kg and the carbon gasification efficiency is no less than 97%. This technology has a bright future in industrialization not only in electricity generation but also in hydrogen production and high value-added chemicals. Given the gas yield obtained in laboratory-scale unit, the hydrogen production cost is U.S.$ 0.111 Nm3 when the throughput capacity is 2000 t/d. A novel thermodynamic cycle power generation system based on coal gasification in supercritical water was proposed with the obvious advantages of high coal-electricity conversion efficiency and zero pollutant emission. The cost of U.S.$ 3.69 billion for desulfuration, denitration and dust removal in China in 2013 would have been saved with this technology. Five kinds of heat supply methods are analyzed and the rates of return of investment are roughly estimated. An integrated cooperative innovation center called a new type of high-efficient coal gasification technology and its large-scale utilization was founded to enhance the industrialization o

关键词： industrialization prospects hydrogen production supercritical water gasification power generation zero emission

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Numerical Analysis of flow Instability in the Water Wall of a Supercritical CFB Boiler with Annular Furnace

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Journal of Thermal Science 2016年第4期25卷 372-379页

作者： XIE Beibei YANG Dong XIE Haiyan NIE Xin LIU Wanyu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

In order to expand the study on flow instability of supercritical circulating fluidized bed(CFB) boiler,a new numerical computational model considering the heat storage of the tube wall metal was presented in this *** lumped parameter method was proposed for wall temperature calculation and the single channel model was adopted for the analysis of flow *** on the time-domain method,a new numerical computational program suitable for the analysis of flow instability in the water wall of supercritical CFB boiler with annular furnace was *** verify the code,calculation results were respectively compared with data of commercial *** to the comparisons,the new code was proved to be reasonable and accurate for practical engineering application in analysis of flow *** on the new program,the flow instability of supercritical CFB boiler with annular furnace was simulated by time-domain *** 1.2 times heat load disturbance was applied on the loop,results showed that the inlet flow rate,outlet flow rate and wall temperature fluctuated with time eventually remained at constant values,suggesting that the hydrodynamic flow was *** results also showed that in the case of considering the heat storage,the flow in the water wall is easier to return to stable state than without considering heat storage.

关键词： supercritical CFB with annular furnace heat storage flow instability wall temperature numerical analysis

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Critical anomaly and finite size scaling of the self-diffusion coefficient for Lennard Jones fluids by non-equilibrium molecular dynamic simulation

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Chinese Physics B 2011年第10期20卷 362-367页

作者： Ahmed Asad 吴江涛 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

We use non-equilibrium molecular dynamics simulations to calculate the self-diffusion coefficient, D, of a Lennard Jones fluid over a wide density and temperature range. The change in self-diffusion coefficient with temperature decreases by increasing density. For density ρ＊ = ρσ3 = 0.84 we observe a peak at the value of the self-diffusion coefficient and the critical temperature T＊ = kT/ε = 1.25. The value of the self-diffusion coefficient strongly depends on system size. The data of the self-diffusion coefficient are fitted to a simple analytic relation based on hydrodynamic arguments. This correction scales as N-α, where α is an adjustable parameter and N is the number of particles. It is observed that the values of a 〈 1 provide quite a good correction to the simulation data. The system size dependence is very strong for lower densities, but it is not as strong for higher densities. The self-diffusion coefficient calculated with non-equilibrium molecular dynamic simulations at different temperatures and densities is in good agreement with other calculations fronl the literature.

关键词： self-diffusion coefficient non-equilibrium molecular dynamic simulation Lennard Jonesfluid critical dynamics

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Calculation of the Critical Speed and Stability Analysis of Cryogenic Turboexpanders with Different Structures

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Plasma Science and Technology 2012年第10期14卷 919-926页

作者：陈双涛赵红利马斌侯予 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

A modularized code based on the Finite Element QZ （FEQZ） method is developed, for a better estimate of the critical speed and a more convenient method of rotor-dynamic stability analysis for a gas bearing high speed turboexpander rotor system with actual structure and application of a cryogenic turboexpander. This code is then validated by the experimental data of a gas bearing turboexpander, with a rotor diameter of 25 mm and a rated speed of 106,400 rpm. With this code, four rotors with different structures, available to the turboexpander, are parametrically analyzed by the available speed range, vibration modes and logarithmic attenuation rate. The results suggest that the rotor with a structure of two thrust collars on the system exhibits a better performance in the designed conditions.

关键词： critical speed gas bearing cryogenic turboexpander

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Experimental Investigation on Critical Heat Flux for Water flowing in a Vertical Uniformly Heated Rifled Tube under Near-critical Pressures

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Journal of Thermal Science 2018年第6期27卷 527-540页

作者： XIE Haiyan YANG Dong ZHAO Yunjie JIANG Huiqing QU Mofeng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

This study experimentally investigated the critical heat flux(CHF) of departure from nucleate boiling(DNB) of water flowing under near-critical pressures in a 2 m-long vertical upward rifled tube with the size of Φ35 × 5.67 mm. Operating conditions included pressures of 18–21 MPa, mass fluxes of 475–1000 kg·m^(-2)·s^(-1), inlet subcooling temperatures of 3–5°C, and wall heat fluxes of 40–960 kW·m^(-2). Tube wall temperature distribution and heat transfer performance in different test conditions were obtained. The effects of the operating parameters on CHF were analyzed. Four heat transfer coefficient correlations were evaluated against our experimental data for further investigation of the two-phase heat transfer characteristics. A heat transfer correlation based on Martinelli number utilized in two-phase region and two empirical correlations used to predict the CHF in rifled tube at near-critical pressures were proposed. Meanwhile, experimental CHF data in rifled tube were compared with six widely used correlations and a CHF look-up table. The CHF enhancement effect in rifled tube is obvious as compared with the CHF data in smooth tube. Results show that DNB occurs at low vapor quality and subcooled region in the rifled tube at near-critical pressures. The increase in pressure leads to the early occurrence of DNB and the decrease in CHF, whereas the increase in mass flux delays the occurrence of DNB and results in the increase in CHF. DNB presents a tendency to move toward the inlet of the rifled tube. At individual operating conditions, DNB and dryout coexist at different sections of the rifled tube.

关键词： critical heat flux near-critical pressure rifled tube DNB heat transfer

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Unveiling micro- and nanoscale bubble dynamics for enhanced electrochemical water splitting

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Advances in Colloid and Interface Science 2025年 343卷 103544页

作者： Lu, Xinlong Yadav, Devendra He, Baichuan Zhou, Yu Zhou, Liwu Zeng, Zilong Ma, Lijing Jing, Dengwei International Research Center for Renewable Energy & State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China Department of Chemical Engineering Technion - Israel Institute of Technology Haifa3200003 Israel College of Mechanical Engineering Xi'an Shiyou University Shaanxi Xi'an710065 China

Bubbles generated during electrochemical and photoelectrochemical water splitting critically influence efficiency through complex factors, including chemical reactions, species transport, mass transfer at the three-phase interface, and bubble coverage. A detailed understanding of the nucleation, growth, coalescence, and detachment of micro- and nanoscale bubbles is vital for advancing water splitting technologies. Surface-attached bubbles significantly reduce the electrocatalytically active area of electrodes, leading to increased surface overpotential at a given current density. Consequently, their effective removal is pivotal for optimizing the electrolysis process. However, the intricate interplay among single bubble evolution, mass transport, bubble coverage, and overpotential remain inadequately understood. This review explores the fundamental mechanisms underpinning bubble evolution, with an emphasis on the Marangoni effect and its influence on bubble dynamics. Furthermore, recent advancements in understanding individual bubbles on micro and nano-electrodes are highlighted, offering valuable insights into scale-dependent bubble behavior. These findings enrich our knowledge of gas-liquid interfacial phenomena and underscore their industrial significance, presenting opportunities to enhance water splitting performance through optimized bubble dynamics. © 2025

关键词： Electrolysis

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