The influences of superheat and cooling intensity on macrostructure and macrosegregation of one new kind duplex stainless steel(DSS)were studied.Thermal simulation equipment was applied to prepare samples,which could ...The influences of superheat and cooling intensity on macrostructure and macrosegregation of one new kind duplex stainless steel(DSS)were studied.Thermal simulation equipment was applied to prepare samples,which could reproduce the industrial processes of DSS manufactured by a vertical continuous slab caster.Macrostructure and macrosegregation were analyzed using the digital single lens reflex and laser-induced breakdown spectroscope(LIBSOPA-200),respectively.The percentage of both chill zone and center equiaxed zone increases with the superheat decreasing,while that of the columnar zone decreases.There is only equiaxed grain existing as the superheat is 10 and 20℃.The lower the superheat is,the coarser the gain size is.High cooling intensity in mold could remarkably decrease the chill zone length and refine the grains in chill zone and center equiaxed zone.The influences of cooling intensity on macrosegregation are greater than those of superheat.The macrosegregation of Si,Mn and Cr is slightly dependent on superheat,while that of Cu,Mo and Ni changes greatly with superheat increasing.展开更多
A new reliable thermal simulation system for studying solidification of heavy section ductile iron has been developed using computer feedback control and artificial intelligent methods. Results of idle test indicate t...A new reliable thermal simulation system for studying solidification of heavy section ductile iron has been developed using computer feedback control and artificial intelligent methods. Results of idle test indicate that the temperature in the system responses exactly to the inputted control data and the temperature control error is less than ±0.5%. It is convenient to simulate solidification of heavy section ductile iron using this new system. Results of thermal simulation experiments show that the differences in nodularity and number of graphite nodule per unit area in the thermal simulation specimen and the actual heavy section block is less than 5% and 10%, respectively.展开更多
The relationship between the t8/5 and micro-hardness, impact toughness in the heat affected zone （HAZ） of ASME SA213-792 at peak temperature of 1 350 ℃ was studied by thermal simulation. The result shows that the m...The relationship between the t8/5 and micro-hardness, impact toughness in the heat affected zone （HAZ） of ASME SA213-792 at peak temperature of 1 350 ℃ was studied by thermal simulation. The result shows that the micro-hardness of HAZ rises at the beginning and then decreases with increasing of t8/5 , whereas the impact toughness presents reverse trend. The distribution of precipitates in substrate has great influence on the impact toughness of HAZ. When the t8/5 is 40 s, chain-like precipitates lower the impact toughness of HAZ seriously.展开更多
The bidirectional subduction system,island arc magmatic activities,and thermal structure of the forearc basin in the Molucca Sea are taken into consideration in this study.The active volcanic arcs on both sides of the...The bidirectional subduction system,island arc magmatic activities,and thermal structure of the forearc basin in the Molucca Sea are taken into consideration in this study.The active volcanic arcs on both sides of the bidirectional subduction zone in the Molucca Sea are undergoing arc-arc collisions.We applied a finite element thermal simulation method to reconstruct the thermal evolution history of the Molucca Sea Plate based on geophysical data.Then,we analyzed the thermodynamic characteristics of island arc volcanism on both sides of the bidirectional subduction zone.The results showed that at 10Myr,the oceanic ridge of the Molucca Sea Plate was asymmetrically biased to the west,causing this bidirectional subduction to be deeper in the west than in the east.Furthermore,the oceanic ridge subducted under the Sangihe arc at 5.5Myr,causing intermittent cessation of volcanic activities.Due to the convergence of bidirectional subduction,the geothermal gradient in the top 3km depth of the forearc area between the Sangihe and Halmahera arcs decreased from about 60℃km^(−1) at 4Myr to about 38℃km^(−1) today.Finally,within the 45–100 km depth range of the sliding surface of the subduction,anomalously high-temperature zones formed due to shear friction during the bidirectional subduction.展开更多
Low maturity coal samples were taken from the Ordos Basin to conduct gold tube thermal simulation experiment in a closed system,and the characteristics of the products were analyzed to find out the fractionation mecha...Low maturity coal samples were taken from the Ordos Basin to conduct gold tube thermal simulation experiment in a closed system,and the characteristics of the products were analyzed to find out the fractionation mechanism of carbon isotopes and the causes of abnormal carbon isotopic compositions of natural gas.At the heating rates of 2℃/h(slow)and 20℃/h(rapid),the low maturity coal samples of the Ordos Basin had the maximum yields of alkane gas of 302.74 mL/g and 230.16 mL/g,theδ13C1 ranges of-34.8‰to-23.6‰and-35.5‰to-24.0‰;δ13C2 ranges of-28.0‰to-9.0‰and-28.9‰to-8.3‰;andδ13C3 ranges of-25.8‰to-14.7‰and-26.4‰to-13.2‰,respectively.Alkane gas in the thermal simulation products of rapid temperature rise process showed obvious partial reversal of carbon isotope series at 550℃,and at other temperatures showed positive carbon isotope series.In the two heating processes,theδ13C1 turned lighter first and then heavier,and the non-monotonic variation of theδ13C1 values is because the early CH4 is from different parent materials resulted from heterogeneity of organic matter or the carbon isotope fractionation formed by activation energy difference of early enriched 12CH4 and late enriched 13CH4.The reversal of carbon isotope values of heavy hydrocarbon gas can occur not only in high to over mature shale gas(oil-type gas),but also in coal-derived gas.Through thermal simulation experiment of toluene,it is confirmed that the carbon isotope value of heavy hydrocarbon gas can be reversed and inversed at high to over mature stage.The isotope fractionation effect caused by demethylation and methyl linkage of aromatic hydrocarbons may be an important reason for carbon isotope inversion and reversal of alkane gas at the high to over mature stage.展开更多
This work presents an algorithm for simulating more accurate temperature distribution in two-phase liquid cooling for three-dimensional integrated circuits than the state of-the-art methods by utilizing local multi-li...This work presents an algorithm for simulating more accurate temperature distribution in two-phase liquid cooling for three-dimensional integrated circuits than the state of-the-art methods by utilizing local multi-linear interpolation techniques on heat transfer coefficients between the microchannel and silicon substrate, and considering the interdependence between the thermal conductivity of silicon and temperature values. The experimental results show that the maximum and average errors are only 9.7% and 6.7% compared with the measurements, respectively.展开更多
In this study,we simulated the thermal behavior of the mud-brick walls of a Nubian vault.We used EnergyPlus software for the simulation.The results obtained showed that the indoor temperature varies from 25.5℃ to 26....In this study,we simulated the thermal behavior of the mud-brick walls of a Nubian vault.We used EnergyPlus software for the simulation.The results obtained showed that the indoor temperature varies from 25.5℃ to 26.5℃ for the period of January 2018.It varies from 33.2℃ to 33.6℃ with an average value of 33.1℃ for the month of April 2018.For the period of July 2018,it varies from 30.3℃ to 32.2℃ with an average value of 31.2℃..Relative humidity for the period of July ranged from 62.3%to 73.5%,with an average value of 67.9%.The simulation enabled us to compare simulated and measured temperature and humidity values.We found that the level of thermal comfort in the Nubian vault is acceptable in both cool and hot periods.In view of these results,we can say that the Nubian vault is an architecture suited to our climate.The technical concept of the Nubian vault is adapted to the climatic conditions and traditional know-how of the Sahel.We also found that the use of raw earth,a locally available material,and the Nubian vault architectural process,contribute to thermal comfort and a reappropriation of local and adapted know-how.展开更多
There are two sets of thermal reservoirs with different rock types in the Gucheng geothermalfield of Hebei Province,namely the Ordovician fractured carbonate thermal reservoir and the Neogene Guantao sandstone thermal...There are two sets of thermal reservoirs with different rock types in the Gucheng geothermalfield of Hebei Province,namely the Ordovician fractured carbonate thermal reservoir and the Neogene Guantao sandstone thermal reservoir,each developed using independent well networks.The energy demand per unit area in the region is high,and the existing geothermal development methods cannot meet the regional energy demand.For this type of block,combined with the development characteristics of different types of thermal reservoirs,numerical simulation methods were used to study the geothermal development trends of Ordovician fractured carbonate reservoirs and Neogene Guantao Formation sandstone reservoirs.When simulating sandstone thermal storage,priority should be given to demonstrating the optimal rechargeflow rate,while in simulating carbonate thermal storage,the focus should be on considering the influence of fracture development direction on development trends.Through numerical simulation of thermal storage development and combined with well network design,the optimal well spacing,production reinjectionflow rate,and reinjection temperature for two sets of thermal reservoirs developed using the same well network were determined.It is predicted that the average heatflow in the study can increase by 47.8%.This study presents reasonable development technical countermeasures to maximize the heating capacity of the geothermal development zone and provides an effective reference for the efficient development of similar geothermal resources in the Bohai Bay Basin.展开更多
STF is a superconducting RF test facility constructed at the high energy accelerator research Organization of Japan （KEK）, as a main part of a R＆D project for the proposed International Linear Collider （ILC） in A...STF is a superconducting RF test facility constructed at the high energy accelerator research Organization of Japan （KEK）, as a main part of a R＆D project for the proposed International Linear Collider （ILC） in Asia. Thermal study of the STF 1.3 GHz 9-cell cavity cryomodule was carried out within a collaboration between China and Japan. Static and dynamic thermal behaviors of the STF cryomodule were simulated and analyzed with the FEM method, and some simulation results were compared with the available experimental data. This paper presents the details.展开更多
A thermal simulation experiment of diagenesis,hydrocarbon generation and evolution of the organic matter-rich shale was carried out to investigate formation and evolution of organic pores under the constraint from imm...A thermal simulation experiment of diagenesis,hydrocarbon generation and evolution of the organic matter-rich shale was carried out to investigate formation and evolution of organic pores under the constraint from immature,low mature,mature,high mature to overmature geological conditions.The argon ion polishingefield emission scanning electron microscope was used to analyze microscopic features of original samples and simulated samples of various evolution stages.Results showed organic pores could be formed during hydrocarbon generation from biochemical and hypothermal processes in the immature and low mature stages,and the shale shallow-buried depth might be favorable for preservation of organic pores;the generation and evolution of organic pores were of heterogeneity,and the maturity was not a decisive factor which controlled formation and development of organic pores,while the difference in physiochemical structure of organic matter played an important role in formation and evolution of organic pores;the organic pore development was obviously related with the retained oil,and the organic pores formed in the oil generation stage were easily filled by pyrolysis asphalt;organic contraction fractures/organic marginal pores might be important storage spaces for shale gas occurrence,and their development was mainly controlled by the physiochemical structure and evolution degree of organic matters when the chemical adsorbed organic matter was converted into the physical adsorbed organic matter and the free organic matter.展开更多
Sustainable building design in dry tropical areas recommends reducing exposure of buildings to solar radiation and/or designing efficient enclosures with satisfactory thermal inertia.We propose in this paper a study o...Sustainable building design in dry tropical areas recommends reducing exposure of buildings to solar radiation and/or designing efficient enclosures with satisfactory thermal inertia.We propose in this paper a study of the influence of the infiltration rate in the building and the coefficient of thermal transfer by convection of the walls, on the thermal comfort using TRNSYS software. All the models carried out were validated by recognized scientific criteria, namely correlation （R） and determination （R2） coefficients on the one hand and NBME and CVRMSE coefficients defined by ASHARE, 2002 on the other hand. The results obtained indicate that the modulation of the air infiltration rate allows the simulations on TRNSYS to be compared to in-situ measurements, with an annual average relative difference of 2.86% on the temperature difference. Furthermore, depending on the parameterization of the heat transfer coefficients by convection of the internal and external walls of walls used in the STD, the average annual difference can be reduced by 1% to 4% between the predictions and the measurements.展开更多
With establishment of thermal and numerical simulation models,the influence of reduction amount on solidification structure,segregation and shrinkage porosity of continuous casting(CC)billets was investigated.The ther...With establishment of thermal and numerical simulation models,the influence of reduction amount on solidification structure,segregation and shrinkage porosity of continuous casting(CC)billets was investigated.The thermal–mechanical coupled simulation results indicated that with an increase in reduction amount,the temperature in the central area decreases,and the reduction efficiency firstly increases and then decreases,reaching the maximum value at reduction amount of 6 mm.Metallographic analysis showed that increasing the reduction amount is beneficial for the refinement of central solidification structure.Moreover,the internal cracks are more likely to appear at higher reduction efficiency.The X-ray computerized tomography results revealed that a higher reduction amount can significantly reduce the volume fraction and equivalent diameter of the central shrinkage porosities of CC billets and increase the sphericity of them.Simultaneously,the macrosegregation of carbon along the central line is improved as the reduction amount increases;while the reduction amount exceeds 8 mm,the segregation degree will not change any more.展开更多
This paper presents a customized simulation system for analyzing welding temperature field, which is based on Finite elementary Analysis software MSC. Marc. The system has the functions of robustly hexahedral meshing,...This paper presents a customized simulation system for analyzing welding temperature field, which is based on Finite elementary Analysis software MSC. Marc. The system has the functions of robustly hexahedral meshing, automated loading of dynamic heat source models for various welding methods and convenient post-processing for welding temperature field. A gene unit algorithm is presented to achieve robust simulation for assembled structure. High order routine method is used to generate various customized routines robustly, which includes Fortran subroutines for welding heat source, Marc command routines for automated modeling, and python subroutines for post-processing etc. With the system, simulation of welding temperature fields can be easily conducted with simple operations.展开更多
Based on the chasteal nucleation theory, the kinetic precipitation model of carbon - nitride particles in weld HAZ is proposed. Using the model,welding simulation technology and the quantitative metallo- graphic anal...Based on the chasteal nucleation theory, the kinetic precipitation model of carbon - nitride particles in weld HAZ is proposed. Using the model,welding simulation technology and the quantitative metallo- graphic analysis,the precipitation transformation temperatue (PTT) curve is obtained.The data from the simulated welds are in good apreement with the value that the PTT curves predicated.展开更多
In order to better understand twin-roll casting process,a 3D finite element method(FEM) simulation was carried out,based on the conditions of the pilot vertical twin-roll caster,to study the thermal flow and solidific...In order to better understand twin-roll casting process,a 3D finite element method(FEM) simulation was carried out,based on the conditions of the pilot vertical twin-roll caster,to study the thermal flow and solidification behavior in the twin-roll casting process.The simulation results show that non-uniform temperature and velocity distribution near the side dam region are the main reason for causing non-uniform solidification and non-uniform deformation along the cast sheet width.Therefore,it is necessary to preheat the side dams or improve the design of nozzle to compensate the effect of side dams on the casting process.High quality magnesium sheets have been cast after improved the casting devices.展开更多
In this paper, thermoelastic problem of onedimensional copper rod under thermal shock is simulated using molecular dynamics method by adopting embedded atom method potential. The rod is on axis x, the left outermost s...In this paper, thermoelastic problem of onedimensional copper rod under thermal shock is simulated using molecular dynamics method by adopting embedded atom method potential. The rod is on axis x, the left outermost surface of which is traction free and the right outermost surface is fixed. Free boundary condition is imposed on the outermost surfaces in direction y and z. The left and right ends of the rod are subjected to hot and cold baths, respectively. Temperature, displacement and stress distributions are obtained along the rod at different moments, which are shown to be limited in the mobile region, indicating that the heat propagation speed is limited rather than infinite. This is consistent with the prediction given by generalized thermoelastic theory. From simulation results we find that the speed of heat conduction is the same as the speed of thermal stress wave. In the present paper, the simulations are conducted using the large-scale atomic/molecular massively parallel simulator and completed visualization software.展开更多
The high working junction temperature of power component is the most common reason of its failure. So the thermal design is of vital importance in electronic control unit （ECU） design. By means of circuit simulation...The high working junction temperature of power component is the most common reason of its failure. So the thermal design is of vital importance in electronic control unit （ECU） design. By means of circuit simulation, the thermal design of ECU for electronic unit pump （EUP） fuel system is applied. The power dissipation model of each power component in the ECU is created and simulated. According to the analyses of simulation results, the factors which affect the power dissipation of components are analyzed. Then the ways for reducing the power dissipation of power components are carried out. The power dissipation of power components at different engine state is calculated and analyzed. The maximal power dissipation of each power component in all possible engine state is also carried out based on these simulations. A cooling system is designed based on these studies. The tests show that the maximum total power dissipation of ECU drops from 43.2 W to 33.84 W after these simulations and optimizations. These applications of simulations in thermal design of ECU can greatly increase the quality of the design, save the design cost and shorten design time展开更多
When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large-sized steel castings, aluminum castings and etc. Some defects of hot cracking by therm...When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large-sized steel castings, aluminum castings and etc. Some defects of hot cracking by thermal stress often appear during solidification process as these castings are produced, which results in failure of castings. Therefore predicting the effects of technological parameters for production of castings on the thermal stress during solidification process becomes an important means. In this paper, the mathematical models have been established and numerical calculation of temperature fields by using finite difference method (FDM) and then thermal stress fields by using finite element method (FEM) during solidification process of castings have been carried out. The technological parameters of production have been optimized by the results of calculation and the defects of hot cracking have been eliminated. Modeling and simulation of 3D thermal stress during solidification processes of large-sized castings provided a scientific basis, which promoted further development of advanced manufacturing technique.展开更多
Three-dimensional thermal a nalysis simulation of a horizontal zone refining system is conducted for germanimn semiconductor materials. The considered geometry includes a g＇ral）hite boat filled with germanium placed...Three-dimensional thermal a nalysis simulation of a horizontal zone refining system is conducted for germanimn semiconductor materials. The considered geometry includes a g＇ral）hite boat filled with germanium placed in a cylindrical quartz tube. A flow of Ar and H2 gas mixture is purged througll the tube. A narrow section of the, boat is assmned to be exposed to a constant heat rate produced b v an rf coil located outside the quartz tube. The results of this analysis provide essential information about various parameters such as the shape of tile molten zone, required power and temperature gradient in the system.展开更多
The lattice thermal conductivity of boron nitride nanoribbon（BNNR） is calculated by using equilibrium molecular dynamics（EMD） simulation method. The Green–Kubo relation derived from linear response theory is used...The lattice thermal conductivity of boron nitride nanoribbon（BNNR） is calculated by using equilibrium molecular dynamics（EMD） simulation method. The Green–Kubo relation derived from linear response theory is used to acquire the thermal conductivity from heat current auto-correlation function（HCACF）. HCACF of the selected BNNR system shows a tendency of a very fast decay and then be followed by a very slow decay process,finally,approaching zero approximately within 3 ps. The convergence of lattice thermal conductivity demonstrates that the thermal conductivity of BNNR can be simulated by EMD simulation using several thousands of atoms with periodic boundary conditions. The results show that BNNR exhibit lower thermal conductivity than that of boron nitride（BN） monolayer,which indicates that phonons boundary scatting significantly suppresses the phonons transport in BNNR. Vacancies in BNNR greatly affect the lattice thermal conductivity,in detail,only 1% concentration of vacancies in BNNR induce a 60% reduction of the lattice thermal conductivity at room temperature.展开更多
基金National Key Research and Development Program of China(No.2017YFB0701802)NSFC(Nos.51504148 and U1760204).
文摘The influences of superheat and cooling intensity on macrostructure and macrosegregation of one new kind duplex stainless steel(DSS)were studied.Thermal simulation equipment was applied to prepare samples,which could reproduce the industrial processes of DSS manufactured by a vertical continuous slab caster.Macrostructure and macrosegregation were analyzed using the digital single lens reflex and laser-induced breakdown spectroscope(LIBSOPA-200),respectively.The percentage of both chill zone and center equiaxed zone increases with the superheat decreasing,while that of the columnar zone decreases.There is only equiaxed grain existing as the superheat is 10 and 20℃.The lower the superheat is,the coarser the gain size is.High cooling intensity in mold could remarkably decrease the chill zone length and refine the grains in chill zone and center equiaxed zone.The influences of cooling intensity on macrosegregation are greater than those of superheat.The macrosegregation of Si,Mn and Cr is slightly dependent on superheat,while that of Cu,Mo and Ni changes greatly with superheat increasing.
文摘A new reliable thermal simulation system for studying solidification of heavy section ductile iron has been developed using computer feedback control and artificial intelligent methods. Results of idle test indicate that the temperature in the system responses exactly to the inputted control data and the temperature control error is less than ±0.5%. It is convenient to simulate solidification of heavy section ductile iron using this new system. Results of thermal simulation experiments show that the differences in nodularity and number of graphite nodule per unit area in the thermal simulation specimen and the actual heavy section block is less than 5% and 10%, respectively.
文摘The relationship between the t8/5 and micro-hardness, impact toughness in the heat affected zone （HAZ） of ASME SA213-792 at peak temperature of 1 350 ℃ was studied by thermal simulation. The result shows that the micro-hardness of HAZ rises at the beginning and then decreases with increasing of t8/5 , whereas the impact toughness presents reverse trend. The distribution of precipitates in substrate has great influence on the impact toughness of HAZ. When the t8/5 is 40 s, chain-like precipitates lower the impact toughness of HAZ seriously.
基金supported by the Natural Science Foundation of Shandong Province(No.ZR2021MD069)the Strategic Pioneer Science and Technology Special Project of the Chinese Academy of Sciences(No.XDB42020104)+1 种基金the National Natural Science Foundation of China(No.42176052)the Project of Introducing and Cultivating Young Talents in the Universities of Shandong Province(No.LUJIAOKEHAN-2021-51).
文摘The bidirectional subduction system,island arc magmatic activities,and thermal structure of the forearc basin in the Molucca Sea are taken into consideration in this study.The active volcanic arcs on both sides of the bidirectional subduction zone in the Molucca Sea are undergoing arc-arc collisions.We applied a finite element thermal simulation method to reconstruct the thermal evolution history of the Molucca Sea Plate based on geophysical data.Then,we analyzed the thermodynamic characteristics of island arc volcanism on both sides of the bidirectional subduction zone.The results showed that at 10Myr,the oceanic ridge of the Molucca Sea Plate was asymmetrically biased to the west,causing this bidirectional subduction to be deeper in the west than in the east.Furthermore,the oceanic ridge subducted under the Sangihe arc at 5.5Myr,causing intermittent cessation of volcanic activities.Due to the convergence of bidirectional subduction,the geothermal gradient in the top 3km depth of the forearc area between the Sangihe and Halmahera arcs decreased from about 60℃km^(−1) at 4Myr to about 38℃km^(−1) today.Finally,within the 45–100 km depth range of the sliding surface of the subduction,anomalously high-temperature zones formed due to shear friction during the bidirectional subduction.
基金Supported by the National Natural Science Foundation of China(41902160,41625009)the China Postdoctoral Science Foundation(2019M650967,2020T130721)the China National Science and Technology Major Project(2016ZX05007-001)
文摘Low maturity coal samples were taken from the Ordos Basin to conduct gold tube thermal simulation experiment in a closed system,and the characteristics of the products were analyzed to find out the fractionation mechanism of carbon isotopes and the causes of abnormal carbon isotopic compositions of natural gas.At the heating rates of 2℃/h(slow)and 20℃/h(rapid),the low maturity coal samples of the Ordos Basin had the maximum yields of alkane gas of 302.74 mL/g and 230.16 mL/g,theδ13C1 ranges of-34.8‰to-23.6‰and-35.5‰to-24.0‰;δ13C2 ranges of-28.0‰to-9.0‰and-28.9‰to-8.3‰;andδ13C3 ranges of-25.8‰to-14.7‰and-26.4‰to-13.2‰,respectively.Alkane gas in the thermal simulation products of rapid temperature rise process showed obvious partial reversal of carbon isotope series at 550℃,and at other temperatures showed positive carbon isotope series.In the two heating processes,theδ13C1 turned lighter first and then heavier,and the non-monotonic variation of theδ13C1 values is because the early CH4 is from different parent materials resulted from heterogeneity of organic matter or the carbon isotope fractionation formed by activation energy difference of early enriched 12CH4 and late enriched 13CH4.The reversal of carbon isotope values of heavy hydrocarbon gas can occur not only in high to over mature shale gas(oil-type gas),but also in coal-derived gas.Through thermal simulation experiment of toluene,it is confirmed that the carbon isotope value of heavy hydrocarbon gas can be reversed and inversed at high to over mature stage.The isotope fractionation effect caused by demethylation and methyl linkage of aromatic hydrocarbons may be an important reason for carbon isotope inversion and reversal of alkane gas at the high to over mature stage.
文摘This work presents an algorithm for simulating more accurate temperature distribution in two-phase liquid cooling for three-dimensional integrated circuits than the state of-the-art methods by utilizing local multi-linear interpolation techniques on heat transfer coefficients between the microchannel and silicon substrate, and considering the interdependence between the thermal conductivity of silicon and temperature values. The experimental results show that the maximum and average errors are only 9.7% and 6.7% compared with the measurements, respectively.
文摘In this study,we simulated the thermal behavior of the mud-brick walls of a Nubian vault.We used EnergyPlus software for the simulation.The results obtained showed that the indoor temperature varies from 25.5℃ to 26.5℃ for the period of January 2018.It varies from 33.2℃ to 33.6℃ with an average value of 33.1℃ for the month of April 2018.For the period of July 2018,it varies from 30.3℃ to 32.2℃ with an average value of 31.2℃..Relative humidity for the period of July ranged from 62.3%to 73.5%,with an average value of 67.9%.The simulation enabled us to compare simulated and measured temperature and humidity values.We found that the level of thermal comfort in the Nubian vault is acceptable in both cool and hot periods.In view of these results,we can say that the Nubian vault is an architecture suited to our climate.The technical concept of the Nubian vault is adapted to the climatic conditions and traditional know-how of the Sahel.We also found that the use of raw earth,a locally available material,and the Nubian vault architectural process,contribute to thermal comfort and a reappropriation of local and adapted know-how.
基金Science and Technology Project of China Petroleum and Chemical Corporation Limited(No.KLJP23008).
文摘There are two sets of thermal reservoirs with different rock types in the Gucheng geothermalfield of Hebei Province,namely the Ordovician fractured carbonate thermal reservoir and the Neogene Guantao sandstone thermal reservoir,each developed using independent well networks.The energy demand per unit area in the region is high,and the existing geothermal development methods cannot meet the regional energy demand.For this type of block,combined with the development characteristics of different types of thermal reservoirs,numerical simulation methods were used to study the geothermal development trends of Ordovician fractured carbonate reservoirs and Neogene Guantao Formation sandstone reservoirs.When simulating sandstone thermal storage,priority should be given to demonstrating the optimal rechargeflow rate,while in simulating carbonate thermal storage,the focus should be on considering the influence of fracture development direction on development trends.Through numerical simulation of thermal storage development and combined with well network design,the optimal well spacing,production reinjectionflow rate,and reinjection temperature for two sets of thermal reservoirs developed using the same well network were determined.It is predicted that the average heatflow in the study can increase by 47.8%.This study presents reasonable development technical countermeasures to maximize the heating capacity of the geothermal development zone and provides an effective reference for the efficient development of similar geothermal resources in the Bohai Bay Basin.
基金Supported by National Natural Science Foundation of China (10525525)China Postdoctoral Science Foundation(20070410637)
文摘STF is a superconducting RF test facility constructed at the high energy accelerator research Organization of Japan （KEK）, as a main part of a R＆D project for the proposed International Linear Collider （ILC） in Asia. Thermal study of the STF 1.3 GHz 9-cell cavity cryomodule was carried out within a collaboration between China and Japan. Static and dynamic thermal behaviors of the STF cryomodule were simulated and analyzed with the FEM method, and some simulation results were compared with the available experimental data. This paper presents the details.
基金supported by the National Science and Technology Major Project of China(No.2017ZX05036002-004,No.2017ZX05005001-003)National Natural Science Foundation of China(No.U1663202,No.41690133)Sinopec Science and Technology Research Project(P14040).
文摘A thermal simulation experiment of diagenesis,hydrocarbon generation and evolution of the organic matter-rich shale was carried out to investigate formation and evolution of organic pores under the constraint from immature,low mature,mature,high mature to overmature geological conditions.The argon ion polishingefield emission scanning electron microscope was used to analyze microscopic features of original samples and simulated samples of various evolution stages.Results showed organic pores could be formed during hydrocarbon generation from biochemical and hypothermal processes in the immature and low mature stages,and the shale shallow-buried depth might be favorable for preservation of organic pores;the generation and evolution of organic pores were of heterogeneity,and the maturity was not a decisive factor which controlled formation and development of organic pores,while the difference in physiochemical structure of organic matter played an important role in formation and evolution of organic pores;the organic pore development was obviously related with the retained oil,and the organic pores formed in the oil generation stage were easily filled by pyrolysis asphalt;organic contraction fractures/organic marginal pores might be important storage spaces for shale gas occurrence,and their development was mainly controlled by the physiochemical structure and evolution degree of organic matters when the chemical adsorbed organic matter was converted into the physical adsorbed organic matter and the free organic matter.
文摘Sustainable building design in dry tropical areas recommends reducing exposure of buildings to solar radiation and/or designing efficient enclosures with satisfactory thermal inertia.We propose in this paper a study of the influence of the infiltration rate in the building and the coefficient of thermal transfer by convection of the walls, on the thermal comfort using TRNSYS software. All the models carried out were validated by recognized scientific criteria, namely correlation （R） and determination （R2） coefficients on the one hand and NBME and CVRMSE coefficients defined by ASHARE, 2002 on the other hand. The results obtained indicate that the modulation of the air infiltration rate allows the simulations on TRNSYS to be compared to in-situ measurements, with an annual average relative difference of 2.86% on the temperature difference. Furthermore, depending on the parameterization of the heat transfer coefficients by convection of the internal and external walls of walls used in the STD, the average annual difference can be reduced by 1% to 4% between the predictions and the measurements.
基金financially supported by the National Natural Science Foundation of China(Nos.52127807 and 52271035)National Science and Technology Major Project of China(No.J2019-Ⅵ-0023)the fund of the State Key Laboratory of Solidification Processing(Northwestern Polytechnical University)(No.SKLSP202107).
文摘With establishment of thermal and numerical simulation models,the influence of reduction amount on solidification structure,segregation and shrinkage porosity of continuous casting(CC)billets was investigated.The thermal–mechanical coupled simulation results indicated that with an increase in reduction amount,the temperature in the central area decreases,and the reduction efficiency firstly increases and then decreases,reaching the maximum value at reduction amount of 6 mm.Metallographic analysis showed that increasing the reduction amount is beneficial for the refinement of central solidification structure.Moreover,the internal cracks are more likely to appear at higher reduction efficiency.The X-ray computerized tomography results revealed that a higher reduction amount can significantly reduce the volume fraction and equivalent diameter of the central shrinkage porosities of CC billets and increase the sphericity of them.Simultaneously,the macrosegregation of carbon along the central line is improved as the reduction amount increases;while the reduction amount exceeds 8 mm,the segregation degree will not change any more.
基金This work is supported by the National Natural Science Foundation of China under contracts 50904038 and 51175253.
文摘This paper presents a customized simulation system for analyzing welding temperature field, which is based on Finite elementary Analysis software MSC. Marc. The system has the functions of robustly hexahedral meshing, automated loading of dynamic heat source models for various welding methods and convenient post-processing for welding temperature field. A gene unit algorithm is presented to achieve robust simulation for assembled structure. High order routine method is used to generate various customized routines robustly, which includes Fortran subroutines for welding heat source, Marc command routines for automated modeling, and python subroutines for post-processing etc. With the system, simulation of welding temperature fields can be easily conducted with simple operations.
文摘Based on the chasteal nucleation theory, the kinetic precipitation model of carbon - nitride particles in weld HAZ is proposed. Using the model,welding simulation technology and the quantitative metallo- graphic analysis,the precipitation transformation temperatue (PTT) curve is obtained.The data from the simulated welds are in good apreement with the value that the PTT curves predicated.
文摘In order to better understand twin-roll casting process,a 3D finite element method(FEM) simulation was carried out,based on the conditions of the pilot vertical twin-roll caster,to study the thermal flow and solidification behavior in the twin-roll casting process.The simulation results show that non-uniform temperature and velocity distribution near the side dam region are the main reason for causing non-uniform solidification and non-uniform deformation along the cast sheet width.Therefore,it is necessary to preheat the side dams or improve the design of nozzle to compensate the effect of side dams on the casting process.High quality magnesium sheets have been cast after improved the casting devices.
基金supported by the National Natural Science Foundation of China (10872158)
文摘In this paper, thermoelastic problem of onedimensional copper rod under thermal shock is simulated using molecular dynamics method by adopting embedded atom method potential. The rod is on axis x, the left outermost surface of which is traction free and the right outermost surface is fixed. Free boundary condition is imposed on the outermost surfaces in direction y and z. The left and right ends of the rod are subjected to hot and cold baths, respectively. Temperature, displacement and stress distributions are obtained along the rod at different moments, which are shown to be limited in the mobile region, indicating that the heat propagation speed is limited rather than infinite. This is consistent with the prediction given by generalized thermoelastic theory. From simulation results we find that the speed of heat conduction is the same as the speed of thermal stress wave. In the present paper, the simulations are conducted using the large-scale atomic/molecular massively parallel simulator and completed visualization software.
文摘The high working junction temperature of power component is the most common reason of its failure. So the thermal design is of vital importance in electronic control unit （ECU） design. By means of circuit simulation, the thermal design of ECU for electronic unit pump （EUP） fuel system is applied. The power dissipation model of each power component in the ECU is created and simulated. According to the analyses of simulation results, the factors which affect the power dissipation of components are analyzed. Then the ways for reducing the power dissipation of power components are carried out. The power dissipation of power components at different engine state is calculated and analyzed. The maximal power dissipation of each power component in all possible engine state is also carried out based on these simulations. A cooling system is designed based on these studies. The tests show that the maximum total power dissipation of ECU drops from 43.2 W to 33.84 W after these simulations and optimizations. These applications of simulations in thermal design of ECU can greatly increase the quality of the design, save the design cost and shorten design time
文摘When heavy machines and large scaled receiver system of communication equipment are manufactured, it always needs to produce large-sized steel castings, aluminum castings and etc. Some defects of hot cracking by thermal stress often appear during solidification process as these castings are produced, which results in failure of castings. Therefore predicting the effects of technological parameters for production of castings on the thermal stress during solidification process becomes an important means. In this paper, the mathematical models have been established and numerical calculation of temperature fields by using finite difference method (FDM) and then thermal stress fields by using finite element method (FEM) during solidification process of castings have been carried out. The technological parameters of production have been optimized by the results of calculation and the defects of hot cracking have been eliminated. Modeling and simulation of 3D thermal stress during solidification processes of large-sized castings provided a scientific basis, which promoted further development of advanced manufacturing technique.
文摘Three-dimensional thermal a nalysis simulation of a horizontal zone refining system is conducted for germanimn semiconductor materials. The considered geometry includes a g＇ral）hite boat filled with germanium placed in a cylindrical quartz tube. A flow of Ar and H2 gas mixture is purged througll the tube. A narrow section of the, boat is assmned to be exposed to a constant heat rate produced b v an rf coil located outside the quartz tube. The results of this analysis provide essential information about various parameters such as the shape of tile molten zone, required power and temperature gradient in the system.
基金Supported by the Natural Science Foundation of Hubei Province(2014CFB610)the Excellent Young Innovation Team Project of Hubei Province(T201429)
文摘The lattice thermal conductivity of boron nitride nanoribbon（BNNR） is calculated by using equilibrium molecular dynamics（EMD） simulation method. The Green–Kubo relation derived from linear response theory is used to acquire the thermal conductivity from heat current auto-correlation function（HCACF）. HCACF of the selected BNNR system shows a tendency of a very fast decay and then be followed by a very slow decay process,finally,approaching zero approximately within 3 ps. The convergence of lattice thermal conductivity demonstrates that the thermal conductivity of BNNR can be simulated by EMD simulation using several thousands of atoms with periodic boundary conditions. The results show that BNNR exhibit lower thermal conductivity than that of boron nitride（BN） monolayer,which indicates that phonons boundary scatting significantly suppresses the phonons transport in BNNR. Vacancies in BNNR greatly affect the lattice thermal conductivity,in detail,only 1% concentration of vacancies in BNNR induce a 60% reduction of the lattice thermal conductivity at room temperature.
