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学者姓名：夏国栋
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摘要 ：
基于非平衡态分子动力学模拟方法,研究了自由分子区内纳米颗粒的热泳特性.理论研究表明,纳米颗粒与周围气体分子之间的非刚体碰撞效应会明显地改变其热泳特性,经典的Waldmann热泳理论并不适用,但尚未有定量的直接验证.模拟计算结果表明:对于纳米颗粒而言,当气-固相互作用势能较弱或气体温度较高时,气体分子与纳米颗粒之间的非刚体碰撞效应可以忽略, Waldmann热泳理论与分子动力学模拟结果吻合较好;当气-固相互作用势能较强或气体温度较低时,非刚体碰撞效应较为明显, Waldmann热泳理论与模拟结果存在较大误差.基于分子动力学模拟结果,对纳米颗粒的等效粒径进行了修正,并考虑了气体分子与纳米颗粒之间的...
关键词 ：
自由分子区 自由分子区 分子动力学模拟 分子动力学模拟 纳米颗粒 纳米颗粒 热泳力 热泳力
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| GB/T 7714 | 崔杰 , 苏俊杰 , 王军 et al. 自由分子区内纳米颗粒的热泳力计算 [J]. | 物理学报 , 2021 , 70 (05) : 242-250 . |
| MLA | 崔杰 et al. "自由分子区内纳米颗粒的热泳力计算" . | 物理学报 70 . 05 (2021) : 242-250 . |
| APA | 崔杰 , 苏俊杰 , 王军 , 夏国栋 , 李志刚 . 自由分子区内纳米颗粒的热泳力计算 . | 物理学报 , 2021 , 70 (05) , 242-250 . |
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摘要 ：
The nanoparticles suspended in a shear flow are subjected to a shear lift force, which is of great importance for the nanoparticle transport. In previous theoretical analysis on the shear lift, it is usually assumed that the particle temperature is equal to the temperature of the surrounding gas media. However, in some particular applications, the particle temperature can significantly differ from the gas temperature. In the present study, the effect of particle temperature on the shear lift of nanoparticles is investigated and the corresponding formulas of shear lift force are derived based on the gas kinetic theory. For extremely small nanoparticles (with radius R < 2 nm) or large nanoparticles (R > 20 nm), the influence of the particle temperature can be neglected. For the intermediate particle size, the relative error induced by the equal gas-particle temperature can be significant. Our findings can bring an insight into accurate evaluation of the nanoparticle transport properties.
关键词 ：
nanoparticle nanoparticle shear lift force shear lift force gas kinetic theory gas kinetic theory temperature effect temperature effect
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| GB/T 7714 | Su, Jun-Jie , Wang, Jun , Xia, Guo-Dong . Effect of the particle temperature on lift force of nanoparticle in a shear rarefied flow* [J]. | CHINESE PHYSICS B , 2021 , 30 (7) . |
| MLA | Su, Jun-Jie et al. "Effect of the particle temperature on lift force of nanoparticle in a shear rarefied flow*" . | CHINESE PHYSICS B 30 . 7 (2021) . |
| APA | Su, Jun-Jie , Wang, Jun , Xia, Guo-Dong . Effect of the particle temperature on lift force of nanoparticle in a shear rarefied flow* . | CHINESE PHYSICS B , 2021 , 30 (7) . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
Thermophoresis refers to the motion of small particles suspending in a fluid with non-uniform temperature distribution due to the temperature gradient around the particle. Usually, the fluid molecules coming from the hot side carry more kinetic energy than those from the cold side, which results in a net thermophoretic force in the direction opposite to the temperature gradient. Since it was discovered more than 100 years ago, thermophoresis has been of major importance in a variety of applications, where it can play either beneficial role or adverse role, including material synthesis, micro- and nano-fabrication, and environmental science. Therefore, it is necessary to accurately evaluate the thermophoretic force. In the present work, the thermophoretic force on nanoparticles is examined in the free molecule regime by using non-equilibrium molecule dynamics (MD) simulation. It has been widely accepted that the thermophoretic force conforms with the Waldmann equation for large Knudsen numbers. However, due to the effect of the nonrigid-body interactions between the particle and gas molecules, the thermophoretic force on nanoparticles might deviate greatly from the classical theory. In our MD model, a single nanoparticle with a diameter of several nanometers suspends in a diluted gas. The Lennard-Jones (L-J) potential is employed to simulate the intermolecular interactions. To avoid deforming the nanoparticle, the solid molecules within the nanoparticles are linked to their nearest neighbors through a finite extensible nonlinear elastic bonding potential. The thermophoretic force on a nanoparticle is calculated by imposing a harmonic potential on the nanoparticle, which eliminates the effect of the Brownian motion of the nanoparticle on the thermophoresis. The effective thermal conductivity of the ambient gas is employed in Waldmann equation for the thermophoretic force due to the finite volume effect. It is found that the Waldmann theory for thermophoresis is still valid for nanoparticles in the case of weak gas-particle interaction or high gas temperature. With the increase of the gas-particle interaction strength or the decrease of the gas temperature, the Waldmann theory is invalid due to the effect of gas-particle nonrigid-body collisions and the adsorption of gas molecules on the particle surface. By considering the gas-particle nonrigid-body interaction and the modified particle size, the theoretical results for thermophoretic force accord with the MD simulations quite well.
关键词 ：
nanoparticle nanoparticle thermophoretic force thermophoretic force free molecule regime free molecule regime molecular dynamics molecular dynamics
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| GB/T 7714 | Cui Jie , Su Jun-Jie , Wang Jun et al. Thermophoretic force on nanoparticles in free molecule regime [J]. | ACTA PHYSICA SINICA , 2021 , 70 (5) . |
| MLA | Cui Jie et al. "Thermophoretic force on nanoparticles in free molecule regime" . | ACTA PHYSICA SINICA 70 . 5 (2021) . |
| APA | Cui Jie , Su Jun-Jie , Wang Jun , Xia Guo-Dong , Li Zhi-Gang . Thermophoretic force on nanoparticles in free molecule regime . | ACTA PHYSICA SINICA , 2021 , 70 (5) . |
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摘要 ：
文中提出了一种局部加密的新型正弦波纹微通道,采用数值模拟的方法研究局部加密位置(上游、中部、下游)对波纹微通道流动换热性能的影响.结果表明,较矩形直通道,波纹微通道的传热性能显著提高,底面最大温差大幅降低.这主要归结于波纹形状的弯曲壁面使流体产生扰动,促进了流体混合;波纹微通道增加了对流换热面积,增强了对流换热效果.局部加密波纹微通道结构可以进一步促进对流换热,同时也带来流动阻力的增大.在相同泵功下,局部加密型微通道的换热性能由差到好排序依次为上游加密型、中部加密型、下游加密型,较矩形微通道,下游加密的微通道结构的热阻降低了1.54倍～2.15倍.下游加密型微通道促进了流体混合使换热增强,有效改善了通道尾部由于热边界层变厚带来的换热恶化问题.
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| GB/T 7714 | 张晓蒙 , 马丹丹 , 夏国栋 . 局部加密的正弦波纹微通道强化传热的数值研究 [J]. | 东北电力大学学报 , 2021 , 41 (4) : 43-51 . |
| MLA | 张晓蒙 et al. "局部加密的正弦波纹微通道强化传热的数值研究" . | 东北电力大学学报 41 . 4 (2021) : 43-51 . |
| APA | 张晓蒙 , 马丹丹 , 夏国栋 . 局部加密的正弦波纹微通道强化传热的数值研究 . | 东北电力大学学报 , 2021 , 41 (4) , 43-51 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
自由分子区内纳米颗粒的热泳力计算
关键词 ：
分子动力学模拟 分子动力学模拟 热泳力 热泳力 纳米颗粒 纳米颗粒 自由分子区 自由分子区
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| GB/T 7714 | 崔杰 , 苏俊杰 , 王军 et al. 自由分子区内纳米颗粒的热泳力计算 [J]. | 崔杰 , 2021 , 70 (5) : 236-244 . |
| MLA | 崔杰 et al. "自由分子区内纳米颗粒的热泳力计算" . | 崔杰 70 . 5 (2021) : 236-244 . |
| APA | 崔杰 , 苏俊杰 , 王军 , 夏国栋 , 李志刚 , 物理学报 . 自由分子区内纳米颗粒的热泳力计算 . | 崔杰 , 2021 , 70 (5) , 236-244 . |
| 导入链接 | NoteExpress RIS BibTex |
摘要 ：
以乙二醇为基液和还原剂,四氯化锡、氯铂酸为氧化剂,采用微流控法合成了铂锡合金纳米流体,并添加了不同比例的聚乙烯吡咯酮(PVP)作为表面活性剂,分别利用紫外可见分光光度计和Hot Disk热物性分析仪测得纳米流体的吸光度值和导热系数,分析了反应温度及PVP的添加比对纳米流体的稳定性、热导率的影响.结果表明,纳米流体导热系数的增长率随反应温度的升高近乎呈现线性增长,虽然稳定性略有下降,但影响不大.添加不同比例的表面活性剂可以有效改善纳米流体的稳定性和导热性能,但存在最佳的添加比例.反应温度为200℃,添加PVP的量为Pt、Sn物质的量浓度和的4倍时制得的铂锡合金纳米流体在温度为60℃下的导热性能提...
关键词 ：
乙二醇 乙二醇 导热系数 导热系数 微流控 微流控 稳定性 稳定性 表面活性剂 表面活性剂 铂锡合金纳米流体 铂锡合金纳米流体
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| GB/T 7714 | 夏国栋 , 李奥 , 马丹丹 . 铂锡合金纳米流体导热系数与稳定性影响因素分析 [J]. | 北京工业大学学报 , 2021 , 47 (09) : 1056-1063 . |
| MLA | 夏国栋 et al. "铂锡合金纳米流体导热系数与稳定性影响因素分析" . | 北京工业大学学报 47 . 09 (2021) : 1056-1063 . |
| APA | 夏国栋 , 李奥 , 马丹丹 . 铂锡合金纳米流体导热系数与稳定性影响因素分析 . | 北京工业大学学报 , 2021 , 47 (09) , 1056-1063 . |
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摘要 ：
The paper presents a comprehensive review of fundamentals and engineering applications of CO2 flow boiling heat transfer, flow patterns and two-phase pressure drops in macro- and micro-channel evaporators. First, distinctions of macro- and micro-channels are discussed. Second, the review addresses the extensive experimental studies on CO2 flow boiling heat transfer and two-phase flow in macro- and micro-channels. The effects of the physical properties on flow boiling heat transfer, flow patterns and pressure drops are analysed by simulations using various physical property packages. Furthermore, analysis of the existing experimental studies of flow boiling heat transfer is presented and the physical mechanisms are discussed. Next, generalized CO2 flow pattern map and flow pattern based mechanistic flow boiling heat transfer and two phase pressure drop models specially developed for CO2 are discussed. New experimental database of flow boiling heat transfer and diabatic two phase frictional pressure drop have been set up to evaluate the models. Comparative results of the flow pattern map, heat transfer and pressure drop models to the experimental database are analysed. In addition, studies of CO2 flow boiling in enhanced channels are summarized. The oil effects on the flow boiling heat transfer and two phase frictional pressure drop are analyzed and simulated as well. According to the extensive analysis, the physical mechanisms and prediction models of the CO2 flow boiling heat transfer and two phase flow phenomena in evaportaors have been well understood. In the aspect of engineering application, comparisons of simulation results and the experimental data in the real thermal systems are discuseed. Furthermore, research need of CO2 evaporators is discussed. Some practical design methods of CO2 evaporators are recommended according to the analysis. Finally, the potential application of CO2 for high heat flux cooling, thermal and power systems are also discussed. Future research needs in flow boiling heat transfer and two phase flow of CO2 in evaporators and engineering applications are discussed and recommended according to this comprehensive review.
关键词 ：
CO < sub > 2 < CO < sub > 2 < Flow boiling heat transfer Flow boiling heat transfer Flow pattern map Flow pattern map Macro-and micro-channel evaporators Macro-and micro-channel evaporators Models Models sub > sub > Two phase pressure drop Two phase pressure drop
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| GB/T 7714 | Cheng, Lixin , Xia, Guodong , Thome, John R. . Flow boiling heat transfer and two-phase flow phenomena of CO2 in macro-and micro-channel evaporators: Fundamentals, applications and engineering design [J]. | APPLIED THERMAL ENGINEERING , 2021 , 195 . |
| MLA | Cheng, Lixin et al. "Flow boiling heat transfer and two-phase flow phenomena of CO2 in macro-and micro-channel evaporators: Fundamentals, applications and engineering design" . | APPLIED THERMAL ENGINEERING 195 (2021) . |
| APA | Cheng, Lixin , Xia, Guodong , Thome, John R. . Flow boiling heat transfer and two-phase flow phenomena of CO2 in macro-and micro-channel evaporators: Fundamentals, applications and engineering design . | APPLIED THERMAL ENGINEERING , 2021 , 195 . |
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摘要 ：
Sinusoidal wavy microchannels with secondary channels (SWSC) are developed to integrate advantages of the sinusoidal corrugated structure and the introduction of secondary channels in flow boiling enhancement. Flow boiling investigations of acetone are made with variation in the heat flux and mass flux range of 251-512 kg/ (m2.s). The boiling curves, heat transfer coefficients, pressure drops and flow boiling instabilities are systematically investigated. The experimental results show that the SWSC microchannels can achieve better heat removal performance than the conventional rectangular microchannels (R). Besides, the premature ONB and delayed CHF can also be obtained. The increased density of bubble nucleation induced by the enlarged surface area and the liquid stored in the corner regions in the nucleate boiling dominated regime, as well as the continuously developing thin liquid film created by the introduction of secondary channels in the stable liquid film evaporation dominated regime are considered to be the main reasons for the notable enhancement in heat transfer. However, the SWSC microchannels suffer a higher pressure drop penalty. The pressure fluctuations and temperature fluctuations of the SWSC microchannels are also illustrated.
关键词 ：
Flow boiling Flow boiling Heat transfer Heat transfer Microchannel heat sink Microchannel heat sink Pressure drop Pressure drop Secondary channel Secondary channel Sinusoidal wavy microchannel Sinusoidal wavy microchannel
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| GB/T 7714 | Ma, D. D. , Tang, Y. X. , Xia, G. D. . Experimental investigation of flow boiling performance in sinusoidal wavy microchannels with secondary channels [J]. | APPLIED THERMAL ENGINEERING , 2021 , 199 . |
| MLA | Ma, D. D. et al. "Experimental investigation of flow boiling performance in sinusoidal wavy microchannels with secondary channels" . | APPLIED THERMAL ENGINEERING 199 (2021) . |
| APA | Ma, D. D. , Tang, Y. X. , Xia, G. D. . Experimental investigation of flow boiling performance in sinusoidal wavy microchannels with secondary channels . | APPLIED THERMAL ENGINEERING , 2021 , 199 . |
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摘要 ：
The need to understand the flow behavior and film thickness in the single screw expander is very crucial since it is known to be a complex system due to the existence of various flow patterns. The present work reports a computational fluid dynamic analysis of two-phase flow behavior and film thickness through a vertical helical rectangular channel using the volume of fluid (VOF) model. The numerical model is validated against available experimental data of annular flow in the helical rectangular channel. The numerical predictions of velocity field, pressure field and liquid phase distribution are presented as each fluid flows into the helical channel. It is found that the inlet flow inclined angle has a significant influence on the liquid film distribution at the outer side of the helical channel. The effects of curvature ratio and dimensionless pitch on the liquid film distribution, film thickness and liquid holdup are illustrated in detail. In addition, the new relationship between the average liquid film thickness and the liquid holdup is also given, and these results are necessary for the optimization design of the single screw expander prototype. © 2020 Elsevier Ltd
关键词 ：
Computational fluid dynamics Computational fluid dynamics Film thickness Film thickness Liquid films Liquid films Screws Screws Two phase flow Two phase flow Velocity Velocity
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| GB/T 7714 | Liu, Xianfei , Zhang, Hui , Wang, Fang et al. Numerical investigation of flow behavior and film thickness in the single screw expander [J]. | International Journal of Mechanical Sciences , 2021 , 190 . |
| MLA | Liu, Xianfei et al. "Numerical investigation of flow behavior and film thickness in the single screw expander" . | International Journal of Mechanical Sciences 190 (2021) . |
| APA | Liu, Xianfei , Zhang, Hui , Wang, Fang , Xia, Guodong , Li, Zhiqiang , Zhu, Caixia et al. Numerical investigation of flow behavior and film thickness in the single screw expander . | International Journal of Mechanical Sciences , 2021 , 190 . |
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摘要 ：
Experiments of flow regime visualization and identification of air-water two-phase flow were conducted in a horizontal helically coiled rectangular channel. The test superficial liquid and gas velocities are 0.09-2 m/s and 0.18-16 m/s, respectively. Flow regimes were observed with a high-speed video camera and the corresponding local and average void fractions were measured with an electric conductivity probe method and with a quick-close valve method, respectively. Four main flow regimes including unsteady pulsating flow, bubbly flow, intermittent flow, and annular flow were observed. The bubbly flow identification criteria depend on more than 90% bubbles whose chord length was smaller than the channel equivalent diameter. The annular flow identification criteria is the local void fraction in the gas core larger than 0.97. Then the flow regimes and their transition mechanisms are analyzed. Furthermore, new transition criteria among these flow regimes have been proposed. The results show that the critical transition average void fraction from bubbly to intermittent flow is 0.23. A complete air-water flow regime map has been developed for the horizontal helically coiled rectangular channel and the map predicts the observed flow regimes well.
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| GB/T 7714 | Cai, Bo , Xia, Guodong , Cheng, Lixin et al. Flow Regime Visualization and Identification of Air-Water Two-Phase Flow in a Horizontal Helically Coiled Rectangular Channel [J]. | HEAT TRANSFER ENGINEERING , 2021 . |
| MLA | Cai, Bo et al. "Flow Regime Visualization and Identification of Air-Water Two-Phase Flow in a Horizontal Helically Coiled Rectangular Channel" . | HEAT TRANSFER ENGINEERING (2021) . |
| APA | Cai, Bo , Xia, Guodong , Cheng, Lixin , Wang, Zhipeng . Flow Regime Visualization and Identification of Air-Water Two-Phase Flow in a Horizontal Helically Coiled Rectangular Channel . | HEAT TRANSFER ENGINEERING , 2021 . |
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