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heat transport in coupled inhomogeneous chains

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Chinese Physics B 2011年第6期20卷 125-130页

作者：胡涛白萌胡柯唐翌 Department of Physics Xiangtan University

We first investigate the heat transport in a network model consisting of two coupled dimerized chains. Results indicate that the thermal resistance of each chain increases with the decrease of the mass ratio γ. of the two types of atoms. Then, we find, when a light impurity or a heavy one is added in the two coupled homogeneous chains and coupled with a particle of another chain, the interface thermal resistances Rint and Rint present different dependences on the mass ratio γ Finally, a persistent circulation of energy current is observed in coupled inhomogeneous chains with two pairs of interchain coupling.

关键词： heat transport thermal resistance

Estimating the effect of shallow groundwater on diurnal heat transport in a vadose zone

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Frontiers of Earth Science 2016年第3期10卷 513-526页

作者： Jianmei JIANG Lin ZHAO Zhe ZHAI School of Chemical Engineering Tianjin University Tianjin 300072 China School of Environment Science and Engineering Tianjin University Tianjin 300072 China

The influence of shallow groundwater on the diurnal heat transport of the soil profile was analyzed using a soil sensor automatic monitoring system that continu- ously measures temperature and water content of soil profiles to simulate heat transport based on the Philip and de Vries （PDV） model. Three experiments were conducted to measure soil properties at depths of 5 cm, 10 cm, 20 cm, and 30 cm when groundwater tables reached l0 cm, 30 cm, and 60 cm （Experiments I, II, and III）. Results show that both the soil temperature near shallow groundwater and the soil water content were effectively simulated by the PDV model. The root mean square errors of the temperature at depths of 5 cm, 10 cm, and 20 cm were 1.018℃, 0.909℃, and 0.255℃, respectively. The total heat flux generated the convergent and divergent planes in space-time fields with valley values of-161.5 W-m 2 at 7：30 and -234.6 W.m2 at 11：10 in Experiments II and III, respectively. The diurnal heat transport of the saturated soil occurred in five stages, while that of saturated-unsaturated and unsaturated soil profiles occurred in four stages because high moisture content led to high thermal conductivity, which hastened the heat transport.

关键词： heat transport heat flux soil temperature,water content shallow groundwater table

Electron heat transport in an HL－1M Tokamak ECRH Plasma

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Chinese Physics Letters 2003年第11期20卷 1973-1976页

作者：符宏军丁玄同刘仪徐德明 SouthwesternInstituteofPhysics POBox432Chengdu610041

Electron temperature profiles, the normalized temperature gradient length and the electron heat diffusivity calculated by the heat pulse transfer method in a plasma confinement region, are investigated during electron cyclotron resonance heating (ECRH) in an HL-1M tokamak. The electron temperature profiles remain almost constant. The normalized temperature gradient length is in the range of 7-13. Electron heat diffusivity in the ECRH plasmas is larger than that in the ohmically heated plasmas. Electron heat diffusivity during off-axis (ρ < 0.3) ECRH discharge is similar to that during on-axis ECRH discharge.

关键词： Electrons Plasmas heat transport normalized temperature diffusivity plasma radiofrequency heating temperature profiles heat Tokamak devices Electron cyclotron resonance Electron Cyclotron-Resonance heating electron temperature

Modeling Arctic Ocean heat transport and warming episodes in the 20th century caused by the intruding Atlantic Water

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Chinese Journal of Polar Science 2008年第2期19卷 159-167页

作者： Wang Jia Jin Meibing Jun Takahashi Tatsuo Suzuki Igor V Polyakov Kohei Mizobata Moto Ikeda Fancois J. Saucier Markus Meier NOAA Great Lakes Environmental Research Laboratory 4840 S State Road Ann Arbor Michigan 48108 USA International Arctic Research Center University of Alaska Fairbanks 930 Koyukuk Dr. Fairbanks AK 99775USA Frontier Research Center for Global Change 3173-25 Showamachi Kanazawa-ku Yokohama City Kanagawa236-0001 Japan Department of Ocean Science Tokyo University of Marine Science and Technology Tokyo Japan Graduate School of Earth and Environmental Science Hokkaido University Sapporo Hokkaido Japan Institute of Ocean Science University of Quebec at Rimouski 310 Ursulines Street Rimouski G5L 3A1 Canada Rossby Centre Swedish Meteorological and Hydrological Institute Sweden

This study investigates the Arctic Ocean warming episodes in the 20th century using both a high-resolution coupled global climate model and historical observations. The model, with no flux adjustment, reproduces well the Atlantic Water core temperature （AWCT） in the Arctic Ocean and shows that four largest decadalscale warming episodes occurred in the 1930s, 70s, 80s, and 90s, in agreement with the hydrographic observational data. The difference is that there was no pre-warming prior to the 1930s episode, while there were two pre-warming episodes in the 1970s and 80s prior to the 1990s, leading the 1990s into the largest and prolonged warming in the 20th century. Over the last century, the simulated heat transport via Fram Strait and the Barents Sea was estimated to be, on average, 31.32 TW and 14.82 TW, respectively, while the Bering Strait also provides 15.94 TW heat into the west- ern Arctic Ocean. heat transport into the Arctic Ocean by the Atlantic Water via Fram Strait and the Barents Sea correlates significantly with AWCT （ C = 0.75 ） at 0- lag. The modeled North Atlantic Oscillation （NAO） index has a significant correlation with the heat transport （ C = 0.37 ）. The observed AWCT has a significant correlation with both the modeled AWCT （ C =0.49） and the heat transport （ C =0.41 ）. However, the modeled NAO index does not significantly correlate with either the observed AWCT （ C = 0.03 ） or modeled AWCT （ C = 0.16 ） at a zero-lag, indicating that the Arctic climate system is far more complex than expected.

关键词： Arctic Ocean heat transport warming episodes modeling.

Tuning turbulent convection through rough element arrangement

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Journal of Hydrodynamics 2022年第2期34卷 308-314页

作者： Jian-zhao Wu Dao-liang Dong Bo-fu Wang Yu-hong Dong Quan Zhou Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering ScienceShanghai Key Laboratory of Mechanics in Energy EngineeringShanghai UniversityShanghai200072China

The tuning of turbulent Rayleigh-Bénard(RB)convection in a box is realized numerically by designed rough element arrangement.Considering the nonlinear dynamics of the thermal turbulence system,five models with rough elements of different widths and the same height are proposed to tune the fluid flow heat-transport capacity.Numerical simulations are performed using spectral element method for Rayleigh number in the range 10^(6)≤Ra≤10^(9) and a fixed Prandtl number Pr=0.7.It is found that heat transport is enhanced for large roughness widths as the interaction between the large-scale circulation and secondary flows inside the cavity regions between the rough elements promotes the eruptions of thermal plumes,but is suppressed for small ones as more heat are trapped inside the cavities.In all the rough models studied,different scaling exponents for the heat transport are identified and the influences of roughness arrangement on flow structure are studied.

关键词： Rayleigh-Bénard(RB)turbulence heat transport roughness arrangement

Experimental Investigation on Thermal Characteristics of Long Distance Loop heat Pipes

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Journal of Thermal Science 2022年第3期31卷 741-750页

作者： ZHAO Ya’nan YAN Tao LIANG Jingtao Key Laboratory of Space Energy Conversion Technology Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100190China

Loop heat pipes(LHPs)are attractive two-phase thermal control devices for satellites,electronics and many other applications.They are capable of transporting heat efficiently for long distances up to several meters at any orientation.This paper investigated the heat transfer characteristics of loop heat pipes with long distances and small diameter transport lines.Small stainless steel tubes of 2 mm and 3 mm in inner diameters were chosen as liquid lines and vapor lines of the LHPs.The local thermal resistances in the evaporator of the 6 m-LHP were researched and analyzed,which indicated that the thermal resistance between the aluminum block and the vapor in the vapor channel accounted for a major proportion of the total thermal resistance.The effect of heat sink temperatures on the performance of the 6 m-LHP were compared with 10°C,15°C,20°C and 25°C cooling water temperatures.Moreover,the thermal characteristics of LHPs with transport distances of 2 m and 16 m were also experimentally investigated.The 16 m-LHP could achieve a heat transfer capacity of 100 W and the 2 m-LHP could reach more than 339 W,on the premise of the evaporator temperature below 100°C.The thermal resistance of the 2 m-LHP could achieve 0.125°C/W.

关键词： loop heat pipe thermal management heat transport long distance thermal resistance

Nonequilibrium thermodynamics in cavity optomechanics

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Fundamental Research 2023年第1期3卷 75-86页

作者： Jiteng Sheng Cheng Yang Haibin Wu State Key Laboratory of Precision Spectroscopy East China Normal UniversityShanghai 200062China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China Chongqing Key Laboratory of Precision Optics Chongqing Institute of East China Normal UniversityChongqing 401120China Shanghai Research Center for Quantum Sciences Shanghai 201315China

Classical thermodynamics has been a great achievement in dealing with systems that are in equilibrium or near equilibrium.As an emerging field,nonequilibrium thermodynamics provides a general framework for understanding the nonequilibrium processes,particularly in small systems that are typically far-from-equilibrium and are dominated by thermal or quantum fluctuations.Cavity optomechanical systems hold great promise among the various experimental platforms for studying nonequilibrium thermodynamics owing to their high controllability,excellent mechanical performance,and ability to operate deep in the quantum regime.Here,we present an overview of the recent advances in nonequilibrium thermodynamics with cavity optomechanical systems.The experimental results in entropy production assessment,fluctuation theorems,heat transfer,and heat engines are highlighted.

关键词： Cavity optomechanics Nonequilibrium thermodynamics Stochastic thermodynamics Quantum thermodynamics Entropy production Fluctuation theorems heat transport heat engine

Characteristics of subsurface mesoscale eddies in the northwestern tropical Pacifi c Ocean from an eddy-resolving model

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Journal of Oceanology and Limnology 2020年第5期38卷 1421-1434页

作者： XU Anqi YU Fei NAN Feng REN Qiang Institute of Oceanology Chinese Academy of SciencesQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Ocean Circulation and Waves Chinese Academy of SciencesQingdao 266071China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China Marine Dynamic Process and Climate Function Laboratory Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China

Subsurface eddies(SSEs)are common features of the ocean interior.They are particularly abundant in oceanic basins and the vicinity of major intermediate water outfl ows.They are responsible for subsurface transport of mass,heat,and salt.Analysis of high-resolution general circulation model data has revealed the existence of subsurface anticyclonic eddies(SSAEs)and subsurface cyclonic eddies(SSCEs)in the northwestern tropical Pacifi c Ocean.SSEs are abundant east of the Philippines(0°–22°N,120°E–140°E)and in latitude bands between 9°N–17°N east of 140°E.The composite structure of SSEs was investigated.SSEs had a core at about 400-m water depth and their maximum meridional velocity exceeded 10 cm/s.They exhibited two cores with diff erent salinity polarities in the surface and subsurface.Additionally,spatial distributions of heat transport induced by SSEs in the northwestern tropical Pacifi c were presented for the fi rst time.A net equatorward heat fl ux toward a temperature up-gradient was observed.The analysis of eddy-mean fl ow interactions revealed that the circulation is baroclinically and barotropically unstable at diff erent depths and to diff ering degrees.The energy conversions suggest that both barotropic and baroclinic instabilities are responsible for SSE generation east of the Philippines,whereas baroclinic instability caused by a horizontal density gradient and vertical eddy heat fl ux are important between 9°N and 17°N east of 140°E.Meridional movement of the north equatorial current and the north equatorial undercurrent can contribute to SSE generation in our study region.

关键词： the northwestern tropical Pacifi c Ocean subsurface eddies composite structures heat transport energy source

Slowing down the heat in thermoelectrics

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InfoMat 2021年第7期3卷 755-789页

作者： Bingchao Qin Dongyang Wang Li-Dong Zhao School of Materials Science and Engineering Beihang UniversityBeijingChina

heat transport has various applications in solid materials.In particular,the thermoelectric technology provides an alternative approach to traditional methods for waste heat recovery and solid-state refrigeration by enabling direct and reversible conversion between heat and electricity.For enhancing the thermoelectric performance of the materials,attempts must be made to slow down the heat transport by minimizing their thermal conductivity(κ).In this study,a continuously developing heat transport model is reviewed first.Theoretical models for predicting the lattice thermal conductivity(κlat)of materials are summarized,which are significant for the rapid screening of thermoelectric materials with lowκlat.Moreover,typical strategies,including the introduction of extrinsic phonon scattering centers with multidimensions and internal physical mechanisms of materials with intrinsically lowκlat,for slowing down the heat transport are outlined.Extrinsic defect centers with multidimensions substantially scatter various-frequency phonons;the intrinsically lowκlat in materials with various crystal structures can be attributed to the strong anharmonicity resulting from weak chemical bonding,resonant bonding,low-lying optical modes,liquid-like sublattices,off-center atoms,and complex crystal structures.This review provides an overall understanding of heat transport in thermoelectric materials and proposes effective approaches for slowing down the heat transport to depressκlat for the enhancement of thermoelectric performance.

关键词： anharmonicity heat transport phonon scattering thermal conductivity thermoelectric materials