Heat pipe is always bent in the typical application of electronic heat dissipation at high heat flux,which greatly affects its heat transfer performance. The capillary limit of heat transport in the bent micro-grooved...Heat pipe is always bent in the typical application of electronic heat dissipation at high heat flux,which greatly affects its heat transfer performance. The capillary limit of heat transport in the bent micro-grooved heat pipes was analyzed in the vapor pressure drop,the liquid pressure drop and the interaction of the vapor with wick fluid. The bent heat pipes were fabricated and tested from the bending angle,the bending position and the bending radius. The results show that temperature difference and thermal resistance increase while the heat transfer capacity of the heat pipe decreases,with the increase of the bending angles and the bending position closer to the vapor section. However,the effects of bending radius can be ignored. The result agrees well with the predicted equations.展开更多
The sunny-shady slopes effect is a phenomenon that impacts the temperature distribution of high-speed railway subgrades,resulting in uneven frost heaving deformation on the subgrade surface,which in turn causes static...The sunny-shady slopes effect is a phenomenon that impacts the temperature distribution of high-speed railway subgrades,resulting in uneven frost heaving deformation on the subgrade surface,which in turn causes static irregularity in the slab track.Based on the hydraulics theory,a thermal-hydro-mechanical(THM)coupled model of frozen soil is established and verified.We explore the process and characteristics of the temperature field and deformation of soil during the freezing process of high-speed railway subgrades and analyze the track irregularity variation law of China Railway Track SystemⅢslab tracks under uneven frost heaving deformation.The results show that,because the left and right slopes of high-speed railway subgrade are exposed to different amounts of solar radiation,which is the key factor causing uneven frost heaving of subgrade.Different strike angles cause changes in temperature of the subgrade’s upper part and the frost heaving amount on the surface,leading to differences in the deformation of the slab track structure:Increased strike angle weakens the rail level irregularity of the down line and marginally increases the rail level irregularity of the up line,and these become consistent in north-south directions.Therefore,when selecting railway lines in seasonal frozen areas,the west-east direction should be avoided to prevent the extremes in sunny-shady slopes effect on subgrades.展开更多
Within the multi-barrier system for high-level waste disposal,the technological gap formed by combined buffer material block becomes the weak part of buffer layer.In this paper,Gaomiaozi bentonite buffer material with...Within the multi-barrier system for high-level waste disposal,the technological gap formed by combined buffer material block becomes the weak part of buffer layer.In this paper,Gaomiaozi bentonite buffer material with technological gap was studied,the heat transfer induced by liquid water flow and water vapor was embedded into the energy conservation equation.Based on the Barcelona basic model,the coupled thermo-hydro-mechanical model of unsaturated bentonite was established by analyzing the swelling process of bentonite block and the compression process of joint material.The China-Mock-up test was adopted to compare the numerical calculation results with the test results so as to verify the rationality of the proposed model.On this basis,the effect of joint self-healing on dry density,thermal conductivity and permeability coefficient of buffer material was further analyzed.The results show that,with bentonite hydrating and swelling,the joint material gradually increases in dry density,and exhibits comparatively uniform hydraulic and thermal conductivity properties as compacted bentonite block.As a result,the buffer material gradually shifts to homogenization due to the coordinated deformation.展开更多
In this article, we considers the thermodynamics analysis of creeping viscous nanofluid flow in a horizontal ciliated tube under the effects of a uniform magnetic field and porous medium. Moreover, energy analysis is ...In this article, we considers the thermodynamics analysis of creeping viscous nanofluid flow in a horizontal ciliated tube under the effects of a uniform magnetic field and porous medium. Moreover, energy analysis is performed in the presence of an internal heat source and thermal radiation phenomena. The thermal conductivity of base fluid water is strengthened by considering the carbon nanotubes (CNTs). Mathematical formulation operated, results in a set of non-linear coupled partial differential equations. The governed differential system is transformed into an ordinary differential system by considering suitable similarity variables. Exact solutions in the closed form are computed for the temperature, momentum and pressure gradient profiles. In this study, special attention is devoted to the electrical conductivity of the CNTs. Streamlines patterns are also discussed to witness the flow lines for different parameters. Thermodynamics analysis shows that entropy of the current flow system is an increasing function of Brinkmann number, magnetic parameter, nanoparticle concentration parameter and Darcy number.展开更多
基金Project(U0834002) supported by the Joint Funds of the National Nature Science Foundation of China and Guangdong ProvinceProject (2009ZM0134) supported by the Foundational Research Funds for the Central Universities in China
文摘Heat pipe is always bent in the typical application of electronic heat dissipation at high heat flux,which greatly affects its heat transfer performance. The capillary limit of heat transport in the bent micro-grooved heat pipes was analyzed in the vapor pressure drop,the liquid pressure drop and the interaction of the vapor with wick fluid. The bent heat pipes were fabricated and tested from the bending angle,the bending position and the bending radius. The results show that temperature difference and thermal resistance increase while the heat transfer capacity of the heat pipe decreases,with the increase of the bending angles and the bending position closer to the vapor section. However,the effects of bending radius can be ignored. The result agrees well with the predicted equations.
基金Projects(2021YFF0502100,2021YFB2600900)supported by the National Key R&D Program of ChinaProjects(52022085,52278461)supported by the National Natural Science Foundation of ChinaProject(22CXTD0051)supported by Sichuan Youth Science and Technology Innovation Team,China。
文摘The sunny-shady slopes effect is a phenomenon that impacts the temperature distribution of high-speed railway subgrades,resulting in uneven frost heaving deformation on the subgrade surface,which in turn causes static irregularity in the slab track.Based on the hydraulics theory,a thermal-hydro-mechanical(THM)coupled model of frozen soil is established and verified.We explore the process and characteristics of the temperature field and deformation of soil during the freezing process of high-speed railway subgrades and analyze the track irregularity variation law of China Railway Track SystemⅢslab tracks under uneven frost heaving deformation.The results show that,because the left and right slopes of high-speed railway subgrade are exposed to different amounts of solar radiation,which is the key factor causing uneven frost heaving of subgrade.Different strike angles cause changes in temperature of the subgrade’s upper part and the frost heaving amount on the surface,leading to differences in the deformation of the slab track structure:Increased strike angle weakens the rail level irregularity of the down line and marginally increases the rail level irregularity of the up line,and these become consistent in north-south directions.Therefore,when selecting railway lines in seasonal frozen areas,the west-east direction should be avoided to prevent the extremes in sunny-shady slopes effect on subgrades.
基金Projects(52078031,U 2034204)supported by the National Natural Science Foundation of China。
文摘Within the multi-barrier system for high-level waste disposal,the technological gap formed by combined buffer material block becomes the weak part of buffer layer.In this paper,Gaomiaozi bentonite buffer material with technological gap was studied,the heat transfer induced by liquid water flow and water vapor was embedded into the energy conservation equation.Based on the Barcelona basic model,the coupled thermo-hydro-mechanical model of unsaturated bentonite was established by analyzing the swelling process of bentonite block and the compression process of joint material.The China-Mock-up test was adopted to compare the numerical calculation results with the test results so as to verify the rationality of the proposed model.On this basis,the effect of joint self-healing on dry density,thermal conductivity and permeability coefficient of buffer material was further analyzed.The results show that,with bentonite hydrating and swelling,the joint material gradually increases in dry density,and exhibits comparatively uniform hydraulic and thermal conductivity properties as compacted bentonite block.As a result,the buffer material gradually shifts to homogenization due to the coordinated deformation.
文摘In this article, we considers the thermodynamics analysis of creeping viscous nanofluid flow in a horizontal ciliated tube under the effects of a uniform magnetic field and porous medium. Moreover, energy analysis is performed in the presence of an internal heat source and thermal radiation phenomena. The thermal conductivity of base fluid water is strengthened by considering the carbon nanotubes (CNTs). Mathematical formulation operated, results in a set of non-linear coupled partial differential equations. The governed differential system is transformed into an ordinary differential system by considering suitable similarity variables. Exact solutions in the closed form are computed for the temperature, momentum and pressure gradient profiles. In this study, special attention is devoted to the electrical conductivity of the CNTs. Streamlines patterns are also discussed to witness the flow lines for different parameters. Thermodynamics analysis shows that entropy of the current flow system is an increasing function of Brinkmann number, magnetic parameter, nanoparticle concentration parameter and Darcy number.
