A three-dimensional analysis model based on the finite element method （FEM） is developed, which can derive the evolution and distribution characteristics of heat flux deposited on the divertor plate from the surface...A three-dimensional analysis model based on the finite element method （FEM） is developed, which can derive the evolution and distribution characteristics of heat flux deposited on the divertor plate from the surface temperature measured by infrared thermography diagnostics. The numerical simulations of surface heating due to localized power bursts and the power deposition calculations demonstrate that this analysis can provide accurate results and useful information about localized hot spots compared with the normal one- and two-dimensional calculations. In this paper, the details of this three- dimensional analysis are presented, and some results in ohmic heating and electron cyclotron resonant heating （ECRH） discharge on HL-2A are given.展开更多
In order to examine the factors which affect the range of heat transfer in earth surrounding subways, FLAC3D was adopted in this study to analyze these factors, under different conditions, in a systematic manner. When...In order to examine the factors which affect the range of heat transfer in earth surrounding subways, FLAC3D was adopted in this study to analyze these factors, under different conditions, in a systematic manner. When we compare these numerical tests, the results show that the main factors, affecting the heat transfer range are the thermal properties of the surrounding earth, the initial ground temperature and the temperature in the tunnel. The heat transfer coefficient between air and linings has little effect on the temperature distribution around the tunnel. The current results can provide a reference for improving the thermal environment in subways and optimizing the design of subwav ventilation and air conditioning.展开更多
Estimating the oil-water temperatures in flowlines is challenging especially in deepwater and ultra-deepwater offshore applications where issues of flow assurance and dramatic heat transfer are likely to occur due to ...Estimating the oil-water temperatures in flowlines is challenging especially in deepwater and ultra-deepwater offshore applications where issues of flow assurance and dramatic heat transfer are likely to occur due to the temperature difference between the fluids and the surroundings. Heat transfer analysis is very important for the prediction and prevention of deposits in oil and water flowlines, which could impede the flow and give rise to huge financial losses. Therefore, a 3D mathematical model of oil-water Newtonian flow under non-isothermal conditions is established to explore the complex mechanisms of the two-phase oil-water transportation and heat transfer in different flowline inclinations. In this work, a non-isothermal two-phase flow model is first modified and then implemented in the InterFoam solver by introducing the energy equation using OpenFOAM® code. The Low Reynolds Number (LRN) k-ε turbulence model is utilized to resolve the turbulence phenomena within the oil and water mixtures. The flow patterns and the local heat transfer coefficients (HTC) for two-phase oil-water flow at different flowlines inclinations (0°, +4°, +7°) are validated by the experimental literature results and the relative errors are also compared. Global sensitivity analysis is then conducted to determine the effect of the different parameters on the performance of the produced two-phase hydrocarbon systems for effective subsea fluid transportation. Thereafter, HTC and flow patterns for oil-water flows at downward inclinations of 4°, and 7° can be predicted by the models. The velocity distribution, pressure gradient, liquid holdup, and temperature variation at the flowline cross-sections are simulated and analyzed in detail. Consequently, the numerical model can be generally applied to compute the global properties of the fluid and other operating parameters that are beneficial in the management of two-phase oil-water transportation.展开更多
A study on heat transfer performance by thermal fluid coupling simulation for the fouling in a shell-tube heat exchanger used in engineering was presented. The coupling simulation was performed in a fluid and solid do...A study on heat transfer performance by thermal fluid coupling simulation for the fouling in a shell-tube heat exchanger used in engineering was presented. The coupling simulation was performed in a fluid and solid domains under three different fouling conditions: fouling inside the tube, fouling outside the tube, and fouling inside the shell. The flow field, temperature, and pressure distributions in the heat exchanger were solved numerically to analyze the heat transfer performance parameters, such as thermal resistance. It is found that the pressure drop of the heat exchanger and the thermal resistance of the tube wall increase by nearly 30% and 20%, respectively, when the relative fouling thickness reaches 10%. The fouling inside the tube has more impact on the heat transfer performance of the heat exchanger, and the fouling inside the shell has less impact.展开更多
We investigate the thermal characteristics of standard organic light-emitting diodes （OLEDs） using a simple and clear 1D thermal model based on the basic heat transfer theory. The thermal model can accurately estima...We investigate the thermal characteristics of standard organic light-emitting diodes （OLEDs） using a simple and clear 1D thermal model based on the basic heat transfer theory. The thermal model can accurately estimate the device temperature, which is linearly with electrical input power. The simulation results show that there is almost no temperature gradient within the OLED device working under steady state conditions. Furthermore, thermal analysis simulation results show that the surface properties （convective heat transfer coetficient and surface emissivity） of the substrate or cathode can significantly affect the temperature distribution of the OLED.展开更多
According to modeling simulation and experiments study, the heat and mass transtfer phenomenon.in wood during dring processes was analyzed. The results indicate: at initial stage of drying, moisture movement in wood i...According to modeling simulation and experiments study, the heat and mass transtfer phenomenon.in wood during dring processes was analyzed. The results indicate: at initial stage of drying, moisture movement in wood is due to capillary force, heat transfer is major effect, at end stage, moisture movement in wood is due to diffusive transport, heat transfer is less展开更多
The transient performance and optimization of a passive residual heat removal heat exchanger(PRHR HX)were investigated.First,a calculation method was developed for predicting the heat transfer of the PRHR HX.The calcu...The transient performance and optimization of a passive residual heat removal heat exchanger(PRHR HX)were investigated.First,a calculation method was developed for predicting the heat transfer of the PRHR HX.The calculation results were validated through comparisons with ROSA experimental data.The heat-transfer performance of the AP1000 PRHR HX in the initial period was predicted,and it satisfied the design requirements.Second,the distributions of the heat flux,tube-inside/outside heattransfer coefficients,and heat load for the AP1000 PRHR HX over 2000 s were examined.Third,an optimization study was conducted by adjusting the horizontal length and tube diameter.Their effects on the four main heat-transfer parameters and the heat-transfer area were analyzed.Furthermore,the influence of the initial in-containment refueling water storage tank(IRWST)temperature was investigated using an established simulation procedure.The results indicated that it significantly affected the trends of the IRWST temperature and reactor outlet temperature.Finally,the minimum required flow rates over time to maintain the reactor outlet temperature at the safety line were determined for different start-up times.The trends of the minimum required flow rate and the peak flow rate were analyzed.展开更多
The phase change characteristic of the power source of an underwater glider propelled by the ocean＇s thermal energy is the key factor in glider attitude control. A numerical model has been established based on the en...The phase change characteristic of the power source of an underwater glider propelled by the ocean＇s thermal energy is the key factor in glider attitude control. A numerical model has been established based on the enthalpy method to analyze the phase change heat transfer process under convective boundary conditions. Phase change is not an isothermal process, but one that occurs at a range of temperature. The total melting time of the material is very sensitive to the surrounding temperature. When the temperature of the surroundings decreases 8 degrees, the total melting time increases 1.8 times. But variations in surrounding temperature have little effect on the initial temperature of phase change, and the slope of the temperature time history curve remains the same. However, the temperature at which phase change is completed decreases significantly. Our research shows that the phase change process is also affected by container size, boundary conditions, and the power source＇s cross sectional area. Materials stored in 3 cylindrical containers with a diameter of 38ram needed the shortest phase change time. Our conclusions should be helpful in effective design of underwater glider power systems.展开更多
As mining activities expand deeper,deep high-temperature formations seriously threaten the future safe exploitation,while deep geothermal energy has great potential for development.Combining the formation cooling and ...As mining activities expand deeper,deep high-temperature formations seriously threaten the future safe exploitation,while deep geothermal energy has great potential for development.Combining the formation cooling and geothermal mining in mines to establish a thermos-hydraulic coupling numerical model for fractured formation.The study investigates the formation heat transfer behaviour,heat recovery performance and thermal economic benefits influenced during the life cycle.The results show that the accumulation of cold energy during the cold storage phase induces a decline in formation temperature.The heat recovery phase is determined by the extent of the initial cold domain,which contracts inward from the edge and decelerates the heat recovery rate gradually.With groundwater velocity increases,the thermal regulation efficiency gradually increases,the production temperature decreases,while the effective radius and thermal power increase first and then decrease.The injected volume and temperature significantly affect,with higher injection temperatures slowing thermal recovery,and the thermal regulation efficiency is more sensitive to changes in formation permeability and thermal conductivity.The heat extraction performance is positively correlated with all factors.The levelized cost of electricity is estimated at 0.1203$/(kW·h)during the cold storage.During the heat recovery,annual profit is primarily driven by cooling benefits.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 10805016)the National Magnetic Confinement Fusion Science Program,China (Grant No. 2009GB104008).
文摘A three-dimensional analysis model based on the finite element method （FEM） is developed, which can derive the evolution and distribution characteristics of heat flux deposited on the divertor plate from the surface temperature measured by infrared thermography diagnostics. The numerical simulations of surface heating due to localized power bursts and the power deposition calculations demonstrate that this analysis can provide accurate results and useful information about localized hot spots compared with the normal one- and two-dimensional calculations. In this paper, the details of this three- dimensional analysis are presented, and some results in ohmic heating and electron cyclotron resonant heating （ECRH） discharge on HL-2A are given.
基金Projects BK2007145 supported by the Jiangsu Natural Science Foundation of China NCET-04-0454 by the Program for New Century Excellent Talentsin Universities
文摘In order to examine the factors which affect the range of heat transfer in earth surrounding subways, FLAC3D was adopted in this study to analyze these factors, under different conditions, in a systematic manner. When we compare these numerical tests, the results show that the main factors, affecting the heat transfer range are the thermal properties of the surrounding earth, the initial ground temperature and the temperature in the tunnel. The heat transfer coefficient between air and linings has little effect on the temperature distribution around the tunnel. The current results can provide a reference for improving the thermal environment in subways and optimizing the design of subwav ventilation and air conditioning.
文摘Estimating the oil-water temperatures in flowlines is challenging especially in deepwater and ultra-deepwater offshore applications where issues of flow assurance and dramatic heat transfer are likely to occur due to the temperature difference between the fluids and the surroundings. Heat transfer analysis is very important for the prediction and prevention of deposits in oil and water flowlines, which could impede the flow and give rise to huge financial losses. Therefore, a 3D mathematical model of oil-water Newtonian flow under non-isothermal conditions is established to explore the complex mechanisms of the two-phase oil-water transportation and heat transfer in different flowline inclinations. In this work, a non-isothermal two-phase flow model is first modified and then implemented in the InterFoam solver by introducing the energy equation using OpenFOAM® code. The Low Reynolds Number (LRN) k-ε turbulence model is utilized to resolve the turbulence phenomena within the oil and water mixtures. The flow patterns and the local heat transfer coefficients (HTC) for two-phase oil-water flow at different flowlines inclinations (0°, +4°, +7°) are validated by the experimental literature results and the relative errors are also compared. Global sensitivity analysis is then conducted to determine the effect of the different parameters on the performance of the produced two-phase hydrocarbon systems for effective subsea fluid transportation. Thereafter, HTC and flow patterns for oil-water flows at downward inclinations of 4°, and 7° can be predicted by the models. The velocity distribution, pressure gradient, liquid holdup, and temperature variation at the flowline cross-sections are simulated and analyzed in detail. Consequently, the numerical model can be generally applied to compute the global properties of the fluid and other operating parameters that are beneficial in the management of two-phase oil-water transportation.
基金National Natural Science Foundation of China (21878102)
文摘A study on heat transfer performance by thermal fluid coupling simulation for the fouling in a shell-tube heat exchanger used in engineering was presented. The coupling simulation was performed in a fluid and solid domains under three different fouling conditions: fouling inside the tube, fouling outside the tube, and fouling inside the shell. The flow field, temperature, and pressure distributions in the heat exchanger were solved numerically to analyze the heat transfer performance parameters, such as thermal resistance. It is found that the pressure drop of the heat exchanger and the thermal resistance of the tube wall increase by nearly 30% and 20%, respectively, when the relative fouling thickness reaches 10%. The fouling inside the tube has more impact on the heat transfer performance of the heat exchanger, and the fouling inside the shell has less impact.
基金Supported by the National Natural Science Foundation of China under Grant No 11304247the Shaanxi Provincial Research Plan for Young Scientific and Technological New Stars(No 2015KJXX-40)the Youth Foundation of Xi’an University of Post&Telecommunication under Grant Nos 1011215 and 1010473
文摘We investigate the thermal characteristics of standard organic light-emitting diodes （OLEDs） using a simple and clear 1D thermal model based on the basic heat transfer theory. The thermal model can accurately estimate the device temperature, which is linearly with electrical input power. The simulation results show that there is almost no temperature gradient within the OLED device working under steady state conditions. Furthermore, thermal analysis simulation results show that the surface properties （convective heat transfer coetficient and surface emissivity） of the substrate or cathode can significantly affect the temperature distribution of the OLED.
文摘According to modeling simulation and experiments study, the heat and mass transtfer phenomenon.in wood during dring processes was analyzed. The results indicate: at initial stage of drying, moisture movement in wood is due to capillary force, heat transfer is major effect, at end stage, moisture movement in wood is due to diffusive transport, heat transfer is less
基金supported by the Shanghai Nuclear Engineering Research and Design Institute,State Power Investment Corporation
文摘The transient performance and optimization of a passive residual heat removal heat exchanger(PRHR HX)were investigated.First,a calculation method was developed for predicting the heat transfer of the PRHR HX.The calculation results were validated through comparisons with ROSA experimental data.The heat-transfer performance of the AP1000 PRHR HX in the initial period was predicted,and it satisfied the design requirements.Second,the distributions of the heat flux,tube-inside/outside heattransfer coefficients,and heat load for the AP1000 PRHR HX over 2000 s were examined.Third,an optimization study was conducted by adjusting the horizontal length and tube diameter.Their effects on the four main heat-transfer parameters and the heat-transfer area were analyzed.Furthermore,the influence of the initial in-containment refueling water storage tank(IRWST)temperature was investigated using an established simulation procedure.The results indicated that it significantly affected the trends of the IRWST temperature and reactor outlet temperature.Finally,the minimum required flow rates over time to maintain the reactor outlet temperature at the safety line were determined for different start-up times.The trends of the minimum required flow rate and the peak flow rate were analyzed.
基金Supported by the Sustainable Energy Propulsion System Program of 211’s Engineering Foundation, Shanghai Jiaotong University.
文摘The phase change characteristic of the power source of an underwater glider propelled by the ocean＇s thermal energy is the key factor in glider attitude control. A numerical model has been established based on the enthalpy method to analyze the phase change heat transfer process under convective boundary conditions. Phase change is not an isothermal process, but one that occurs at a range of temperature. The total melting time of the material is very sensitive to the surrounding temperature. When the temperature of the surroundings decreases 8 degrees, the total melting time increases 1.8 times. But variations in surrounding temperature have little effect on the initial temperature of phase change, and the slope of the temperature time history curve remains the same. However, the temperature at which phase change is completed decreases significantly. Our research shows that the phase change process is also affected by container size, boundary conditions, and the power source＇s cross sectional area. Materials stored in 3 cylindrical containers with a diameter of 38ram needed the shortest phase change time. Our conclusions should be helpful in effective design of underwater glider power systems.
基金financial support from the National Natural Science Foundation of China(Nos.52434006,52374151,and 51927808)。
文摘As mining activities expand deeper,deep high-temperature formations seriously threaten the future safe exploitation,while deep geothermal energy has great potential for development.Combining the formation cooling and geothermal mining in mines to establish a thermos-hydraulic coupling numerical model for fractured formation.The study investigates the formation heat transfer behaviour,heat recovery performance and thermal economic benefits influenced during the life cycle.The results show that the accumulation of cold energy during the cold storage phase induces a decline in formation temperature.The heat recovery phase is determined by the extent of the initial cold domain,which contracts inward from the edge and decelerates the heat recovery rate gradually.With groundwater velocity increases,the thermal regulation efficiency gradually increases,the production temperature decreases,while the effective radius and thermal power increase first and then decrease.The injected volume and temperature significantly affect,with higher injection temperatures slowing thermal recovery,and the thermal regulation efficiency is more sensitive to changes in formation permeability and thermal conductivity.The heat extraction performance is positively correlated with all factors.The levelized cost of electricity is estimated at 0.1203$/(kW·h)during the cold storage.During the heat recovery,annual profit is primarily driven by cooling benefits.
