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基于能量桩现场试验的土体综合热导率系数研究 被引量:1
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作者 任连伟 孔纲强 +1 位作者 郝耀虎 刘汉龙 《岩土力学》 EI CAS CSCD 北大核心 2019年第12期4857-4864,共8页
能量桩技术兼具支撑上部荷载和浅层地热能换热器双重功能;作为一种节能减排技术,近年来在国内外获得了一定的发展。然而,目前简单套用基于传统地埋管换热器获得的土体综合热导率系数,无法准确计算能量桩换热效率。依托河南理工大学某低... 能量桩技术兼具支撑上部荷载和浅层地热能换热器双重功能;作为一种节能减排技术,近年来在国内外获得了一定的发展。然而,目前简单套用基于传统地埋管换热器获得的土体综合热导率系数,无法准确计算能量桩换热效率。依托河南理工大学某低承台3×3能量桩群桩工程应用,开展基于能量桩的土体综合热导率系数测试现场试验和数值模拟研究,分析加热时长、加热功率、流速及桩长等因素对土体综合热导率系数的影响规律,继而探讨能量桩在群桩中的布置形式对土体综合热导率系数的影响规律。研究结果表明,基于传统地源热泵测试所发展起来的土体综合热导率系数线热源分析方法,并不适用于分析基于能量桩现场实测所获得的相关数据;有必要推导一套考虑桩径影响的、适用于能量桩的土体综合热导率系数测试与计算分析方法。 展开更多
关键词 能量桩 综合热导率系数 现场试验 数值模拟
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热电材料热导率系数测定中误差分析
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作者 孟庆国 刘莹 付淑芳 《黑龙江科技信息》 2014年第25期106-106,共1页
本文对热电材料热导率系数测定中引起误差的因素进行了分析。得出了不同晶体结构、不同试样半径与厚度比、不同测试环境条件下对热导率系数测定所产生的误差进行了分析与探讨,并给出了相应的误差比,对热电材料热导率系数的测定有一定的... 本文对热电材料热导率系数测定中引起误差的因素进行了分析。得出了不同晶体结构、不同试样半径与厚度比、不同测试环境条件下对热导率系数测定所产生的误差进行了分析与探讨,并给出了相应的误差比,对热电材料热导率系数的测定有一定的指导意义。 展开更多
关键词 电材料 热导率系数 误差分析
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Microstructure and properties of electronic packaging box with high silicon aluminum-base alloy by semi-solid thixoforming 被引量:10
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作者 贾琪瑾 刘俊友 +1 位作者 李艳霞 王文韶 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第1期80-85,共6页
The electronic packaging box with high silicon aluminum-base alloy was prepared by semi-solid thixoforming technique.The flow characteristic of the Si phase was analyzed.The microstructures of different parts of the b... The electronic packaging box with high silicon aluminum-base alloy was prepared by semi-solid thixoforming technique.The flow characteristic of the Si phase was analyzed.The microstructures of different parts of the box were observed by optical microscopy and scanning electron microscopy,and the thermophysical and mechanical properties of the box were tested.The results show that there exists the segregation phenomenon between the primary Si phase and the liquid phase during thixoforming,the liquid phase flows from the box,and the primary Si phase accumulates at the bottom of the box.The volume fraction of primary Si phase decreases gradually from the bottom to the walls.Accordingly,the thermal conductivities of bottom center and walls are 107.6 and 131.5 W/(m·K),the coefficients of thermal expansion(CTE) are 7.9×10-6 and 10.6×10-6 K-1,respectively.The flexural strength increases slightly from 167 to 180 MPa.The microstructures and properties of the box show gradient distribution overall. 展开更多
关键词 high silicon aluminum-base alloy electronic packaging semi-solid thixoforming thermal conductivity coefficient of thermal expansion
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Microstructure and thermophysical properties of SiC/Al composites mixed with diamond 被引量:6
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作者 郭宏 韩媛媛 +2 位作者 张习敏 贾成厂 徐骏 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第1期170-174,共5页
The thermophysical properties of the SiC /Al composites mixed with diamond(SiC-Dia/Al) were studied through theoretical calculation and experiments. The thermal conductivity and the thermal expansion coefficient of ... The thermophysical properties of the SiC /Al composites mixed with diamond(SiC-Dia/Al) were studied through theoretical calculation and experiments. The thermal conductivity and the thermal expansion coefficient of the SiC-Dia/Al were calculated by differential effective medium(DEM) theoretical model and extended Turner model, respectively. The microstructure of the SiC-Dia/Al shows that the combination between SiC particles and Al is close, while that between diamond particles and Al is not close. The experimental results of the thermophysical properties of the SiC-Dia/Al are consistent with the calculated ones. The calculation results show that when the volume ratio of the diamond particles to the SiC particles is 3:7, the thermal conductivity and the thermal expansion coefficient can be improved by 39% and 30% compared to SiC/Al composites, respectively. In other words, by adding a small amount of diamond particles, the thermophysical properties of the composites can be improved effectively, while the cost increases little. 展开更多
关键词 SiC/Al composites mixed with diamond thermal conductivity thermal expansion coefficient MICROSTRUCTURE
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Microstructures and properties of Al-45%Si alloy prepared by liquid-solid separation process and spray deposition 被引量:4
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作者 李艳霞 刘俊友 +1 位作者 王文韶 刘国权 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第4期970-976,共7页
The microstructures and properties of A1-45%Si alloy prepared by liquid-solid separation (LSS) process and spray deposition (SD) were studied. The results show that the size, shape and distribution of the primary ... The microstructures and properties of A1-45%Si alloy prepared by liquid-solid separation (LSS) process and spray deposition (SD) were studied. The results show that the size, shape and distribution of the primary Si phase have different influence on the properties of alloys. Comparing with the Si particles with irregular shape, fine size and continuous distribution in SD alloy, the primary Si phase in LSS alloy is sphere-like, coarse and surrounded by the continuous AI matrix. The microstructure features of LSS alloy are beneficial to the higher thermal conductivity and lower thermal expansion coefficient at room temperature. The fine Si particle in SD alloy is advantageous to improving the mechanical properties. The increasing rates of thermal expansion coefficient with temperature are influenced by the distribution of the Si particles, where a lower rate is obtained in SD alloy with continuous Si particles. The agreement of thermal expansion coefficient with the model in LSS alloy differs from that in the SD alloy because of the different microstructure characteristics. 展开更多
关键词 aluminum-silicon alloy Si particle liquid-solid separation spray deposition thermal conductivity thermal expansioncoefficient
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Microstructure and properties of SiC_p/Al electronic packaging shell produced by liquid-solid separation 被引量:3
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作者 郭明海 刘俊友 李艳霞 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第4期1039-1045,共7页
The electronic packaging shell of high silicon carbide (54%SiC, volume fraction) aluminum-based composites was produced by liquid-solid separation technique. The characteristics of distribution and morphology of SiC... The electronic packaging shell of high silicon carbide (54%SiC, volume fraction) aluminum-based composites was produced by liquid-solid separation technique. The characteristics of distribution and morphology of SiC as well as the shell’s fracture surface were examined by optical microscopy and scanning electron microscopy, and the thermo-physical and mechanical properties of the shell were also tested. The results show that Al matrix has a net-like structure while SiC is uniformly distributed in the Al matrix. The SiCp/Al composites have a low density of 2.93 g/cm^3, and its relative density is 98.7%. Thermal conductivity of the composites is 175 W/(·K), coefficient of thermal expansion (CTE) is 10.3×10^-6 K-1 (25-400 ℃), compressive strength is 496 MPa, bending strength is 404.5 MPa, and the main fracture mode is brittle fracture of SiC particles accompanied by ductile fracture of Al matrix.Its thermal conductivity is higher than that of Si/Al alloy, and its CTE matches with that of the chip material. 展开更多
关键词 liquid-solid separation near-net thixoforming SiCp/Al electronic packaging shell thermal conductivity coefficient ofthermal expansion
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Effect of Si content on microstructure and properties of Si/Al composites
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作者 翟蔚宸 张朝晖 +3 位作者 王富耻 神祥博 李树奎 王鲁 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第4期982-988,共7页
Si/Al composites with different Si contents for electronic packaging were prepared by spark plasma sintering (SPS) technique. Properties of the composites were investigated, including density, thermal conductivity, ... Si/Al composites with different Si contents for electronic packaging were prepared by spark plasma sintering (SPS) technique. Properties of the composites were investigated, including density, thermal conductivity, coefficient of thermal expansion and flexural strength. The effects of the Si content on microstructure and thermal and mechanical properties of the composites were studied. The results show that the Si/Al composites consist of Si and Al components and Al uniformly distributes among Si grains. The relative density of the Si/Al composites gradually increases with the decrease of Si content and reaches 98.0% when the Si content is 50%. The thermal conductivity, the coefficient of thermal expansion and the flexural strength of the composite all decrease with the increase of the Si content, and an optimal matching of them is obtained when the Si content is 60%(volume fraction). 展开更多
关键词 spark plasma sintering Si/Al composite thermal conductivity coefficient of thermal expansion flexural strength
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Thermal properties of closed-cell aluminum foams prepared by melt foaming technology 被引量:2
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作者 Hui WANG Xiang-yang ZHOU +2 位作者 Bo LONG Juan YANG Hong-zhuan LIU 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第12期3147-3153,共7页
Closed-cell aluminum foam has incomparable advantages over other traditional materials for thermal insulation and heatpreservation because of small thermal conductivity coefficient. Spherical bubble three-dimensional ... Closed-cell aluminum foam has incomparable advantages over other traditional materials for thermal insulation and heatpreservation because of small thermal conductivity coefficient. Spherical bubble three-dimensional model of aluminum foam is builtto deduce the relationship among pore wall thickness, porosity and average pore size. Non-uniform closed-cell foam aluminummodel with different structural parameters and random pore distribution is established based on the relationship via C programminglanguage. And the temperature distribution is analyzed with ANSYS software. Results indicate that thermal conductivity increaseswith the reducing of porosity. For the aluminum foam with the same porosity, different pore distributions result in different thermalconductivities. The temperature distribution in aluminum foam is non-uniform, which is closely related with the pore size anddistribution. The pores which extend or distribute along the direction perpendicular to heat flow strengthen obstructive capability forheat flow. When pores connect along the direction perpendicular to heat flow, a “wall of high thermal resistance” appears to declinethe thermal conductivity rapidly, which shows that only porosity cannot completely determine effective thermal conductivity ofclosed-cell aluminum foam. 展开更多
关键词 closed-cell aluminum foam thermal conductivity POROSITY pore distribution temperature distribution
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Effect of Adsorbent Diameter on the Performance of Adsorption Refrigeration 被引量:1
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作者 黄宏宇 何兆红 +4 位作者 袁浩然 小林敬幸 赵丹丹 窪田光宏 郭华芳 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2014年第5期602-606,共5页
Adsorbents are important components in adsorption refrigeration. The diameter of an adsorbent can affect the heat and mass transfer of an adsorber. The effect of particle diameter on effective thermal conductivity was... Adsorbents are important components in adsorption refrigeration. The diameter of an adsorbent can affect the heat and mass transfer of an adsorber. The effect of particle diameter on effective thermal conductivity was investigated. The heat transfer coefficient of the refrigerant and the void rate of the adsorbent layer can also affect the effective thermal conductivity of adsorbents. The performance of mass transfer in the adsorber is better when pressure drop decreases. Pressure drop decreases with increasing permeability. The permeability of the adsorbent layer can be improved with increasing adsorbent diameter. The effect of adsorbent diameter on refrigeration output power was experimentally studied. Output power initially increases and then decreases with increasing diameter under different cycle time conditions. Output power increases with decreasing cycle time under similar diameters. 展开更多
关键词 adsorption refrigeration heat and mass transfer adsorbent diameter thermal conduction PERMEABILITY
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Laboratory and field experiment on measurement of soil thermal conductivity by probe method
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作者 ZHANG Tong ZHANG Yanjun +2 位作者 LIU Tong XIE Yangyang ZHANG Chi 《Global Geology》 2015年第4期221-225,共5页
The authors presented a new measuring method of the soil thermal conductivity,the probe method,which is designed and made based on the theory of line heat source. This method is used to measure thermal conductivity of... The authors presented a new measuring method of the soil thermal conductivity,the probe method,which is designed and made based on the theory of line heat source. This method is used to measure thermal conductivity of coarse sand,fine sand and silty clay in different water contents. The results that measured by the probe method are well consistent with those of QTM-D_2. The soil thermal conductivity increases in different levels with the increase of the water content. Compared the soil thermal conductivity measured by the probe method in laboratory with in-situ experiment,it shows that the measuring gap gradually increases with the increase of the depth. The reason is that the in-situ measuring thermal conductivity can reflect the actual situation of the soil mass. 展开更多
关键词 probe method thermal conductivity water content in-situ measurement
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Experimental Evaluation of Thermal Properties of Grouting Materials
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作者 Manuela Campanale Marta Deganello Lorenzo Moro 《Journal of Energy and Power Engineering》 2013年第8期1457-1463,共7页
This study is aimed at the thermal analysis of sealant mortar (usually a mixtures of bentonite and cemem with addition of sand) used in geothermal cooling and heating. In particular, thermal conductivity and diffusi... This study is aimed at the thermal analysis of sealant mortar (usually a mixtures of bentonite and cemem with addition of sand) used in geothermal cooling and heating. In particular, thermal conductivity and diffusivity measurements were performed on differem sealant mixtures by using Hot Disk thermal constants analyzer in order to identify the interesting thermal properties of grouting materials. The grouting materials that we considered are of porous nature and, if used in the presence of groundwater, have different levels of imbibitions. It is important to know the thermal behavior of these materials at different water content. A first set of measurements was performed on a not-tinted material at room temperature; then the samples were led to saturation conditions by contact capillary imbibitions with a cotton wool layer moistened in water. The determination of thermal conductivity in these test conditions appears to be critical compared to the measuremems on non-timed sample. The thermal conductivity tests have revealed how the thermal behavior of the samples analyzed is essentially determined by the density and water content of the material: in fact, the thermal conductivity increases of two to three times the value of the not-tinted material. 展开更多
关键词 Geothermal energy thermal conductivity sealant mortar hot disk grouting materials Portland cement mortar.
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Effective Thermal Conductivity with Convection and Radiation in Packed Bed 被引量:1
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作者 Yusuke Asakuma Tsuyoshi Yamamoto 《Journal of Energy and Power Engineering》 2013年第4期639-646,共8页
Effective thermal conductivity with convection and radiation is analyzed by the homogenization method. This method can precisely represent the microstructure of a packed bed. In this study, the effects of parameters s... Effective thermal conductivity with convection and radiation is analyzed by the homogenization method. This method can precisely represent the microstructure of a packed bed. In this study, the effects of parameters such as the radiation emissivity, temperature, contact area and particle size of the packed bed on the conductivity have been estimated. For example, heat transfer by radiation does not dominate if the material has voids of less than l mm in size. Moreover, the effects of contact area and pressure on effective thermal conductivity are negligible for thermal radiation. By considering the microscopic behavior of a packed bed, the homogenization method is thus a powerful tool for estimating the bed's effective thermal conductivity. 展开更多
关键词 Effective thermal conductivity homogenization method multiscale analysis MICROSTRUCTURE thermal radiation.
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Theoretical and experimental study of the thermal conductivity of nanoporous media 被引量:5
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作者 JIANG PeiXue XIANG Heng XU RuiNa 《Science China(Technological Sciences)》 SCIE EI CAS 2012年第8期2140-2147,共8页
The nanoparticle thermal conductivity and nanoscale thermal contact resistance were investigated by molecular dynamics(MD) simulations to further understand nanoscale porous media thermal conductivity.Macroscale porou... The nanoparticle thermal conductivity and nanoscale thermal contact resistance were investigated by molecular dynamics(MD) simulations to further understand nanoscale porous media thermal conductivity.Macroscale porous media thermal conductivity models were then revised for nanoporous media.The effective thermal conductivities of two packed beds with nanoscale nickel particles and a packed bed with microscale nickel particles were then measured using the Hot Disk.The measured results show that the nano/microscale porous media thermal conductivities were much less than the thermal conductivities of the solid particles.Comparison of the measured and calculated results shows that the revised combined parallel-series model and the revised Hsu-Cheng model can accurately predict the effective thermal conductivities of micro-and nanoparticle packed beds. 展开更多
关键词 thermal conductivity NANOPARTICLE nanoporous media molecular dynamics(MD) simulation contact resistance
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Reconstruction of solid oxide fuel cell electrode microstructure and analysis of its effective conductivity 被引量:4
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作者 Keqing Zheng Meng Ni 《Science Bulletin》 SCIE EI CAS CSCD 2016年第1期78-85,共8页
The effective conductivity (aeff) of solid oxide fuel cell (SOFC) electrode is an important parameter for predicting the ohmic loss in SOFC. This paper investigates the effective conductivity of SOFC electrodes re... The effective conductivity (aeff) of solid oxide fuel cell (SOFC) electrode is an important parameter for predicting the ohmic loss in SOFC. This paper investigates the effective conductivity of SOFC electrodes recon- structed numerically by packing spherical particles in a computational domain, followed by a dilation process to simulate the sintering procedure. The effects of various parameters on the effective conductivity of the electrodes are investigated, including material composition, porosity, particle size and contact angle. Results show that the effective conductivity ratio (aeff/ao) of the computed con- ducting phase is mainly affected by its total volume frac- tion (VF) in electrode (including the porosity). The effective conductivity can be improved by increasing the VF, electrode particle size or the contact angle between electrode particles. Based on the numerical results, the conventional percolation model for the calculation of O'eft is improved by adjusting the Bruggeman factor from 1.5 to 2.7. The results are useful for understanding the microstructure properties of SOFC composite electrode and for subsequent electrode optimization. 展开更多
关键词 Fuel cell ELECTRODE CONDUCTIVITY Modeling Random particle packing
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Conductivity properties of β-SiAlON ceramics 被引量:1
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作者 DONG PengLi WANG XiDong +1 位作者 ZHANG Mei SESHADRI Seetharaman 《Science China(Technological Sciences)》 SCIE EI CAS 2012年第9期2409-2415,共7页
The thermal diffusivity and heat capacity of β-SiAION ceramics with different Z values (0.6, 1.5, 3.0) were measured by laser flash technique and differential scanning calorimetry (DSC), respectively. The thermal... The thermal diffusivity and heat capacity of β-SiAION ceramics with different Z values (0.6, 1.5, 3.0) were measured by laser flash technique and differential scanning calorimetry (DSC), respectively. The thermal conductivity of β-SiAION was calculated from thermal diffusivity, heat capacity and density and it decreased and then kept almost constant with increasing of temperature. Two different models representing effective thermal conductivity were established and the various parameters of these models were simulated based on the results from the present work. The fitted regression lines were in good agreement with the experimental values. 展开更多
关键词 β-SiAION thermal diffusivity heat capacity effective thermal conductivity
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Diffusive Thermal Conductivity of Superfluid Fermi Gas in p-Wave State at Low Temperatures
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作者 M.Khademi Dehkordi S.Nasirimoghadam +1 位作者 F.Nabipoor M.A.Shahzamanian 《Communications in Theoretical Physics》 SCIE CAS CSCD 2012年第12期891-894,共4页
The diffusive thermal conductivity tensor of p-wave superfluid at low temperatures is calculated by using the Boltzmann equation approach. We use the Sykes and Brooker procedure and show that Kxx is equal to Kyy and t... The diffusive thermal conductivity tensor of p-wave superfluid at low temperatures is calculated by using the Boltzmann equation approach. We use the Sykes and Brooker procedure and show that Kxx is equal to Kyy and these are related to T-1, also Kxx is proporated to T-3. 展开更多
关键词 diffusive thermal conductivity superfluid Fermi gas
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