For the sake of a more accurate shell boundary and calculation of radiation heat transfer in the Directional Solidification(DS) process, a radiation heat transfer model based on the Finite Element Method(FEM)is develo...For the sake of a more accurate shell boundary and calculation of radiation heat transfer in the Directional Solidification(DS) process, a radiation heat transfer model based on the Finite Element Method(FEM)is developed in this study. Key technologies, such as distinguishing boundaries automatically, local matrix and lumped heat capacity matrix, are also stated. In order to analyze the effect of withdrawing rate on DS process,the solidification processes of a complex superalloy turbine blade in the High Rate Solidification(HRS) process with different withdrawing rates are simulated; and by comparing the simulation results, it is found that the most suitable withdrawing rate is determined to be 5.0 mm·min^(-1). Finally, the accuracy and reliability of the radiation heat transfer model are verified, because of the accordance of simulation results with practical process.展开更多
The safety analysis code SCTRAN for SCWR(Super Critical Water Reactor) is modified to own the capability to assess the radiation heat transfer with developing a two-dimensional heat conduction solution scheme and inco...The safety analysis code SCTRAN for SCWR(Super Critical Water Reactor) is modified to own the capability to assess the radiation heat transfer with developing a two-dimensional heat conduction solution scheme and incorporating a radiation heat transfer model. The verification of the developed radiation heat transfer model is conducted through code-to-code comparison with CATHENA. The results show that the modified SCTRAN code is successful for that the maximum absolute error and relative error of the surface temperature between results of SCTRAN and CATHENA are 6.1°C and 0.9%, which are acceptable in temperature prediction. Then,with the modified SCTRAN code, the loss of coolant accident with a total loss of emergency core cooling system(LOCA/LOECC) of Canadian-SCWR is carried out to evaluate its "no-core-melt" concept. The following conclusions are achieved: 1) in the process of LOCA, the decay heat can be totally removed by the radiation heat transfer and the natural convection of the high-temperature coolant, even without an intervention of ECCS(Emergency Core Cooling System); 2) The peak cladding temperature of the fuel pins in the inner and outer rings of the high power group are 1236°C and 1177°C respectively, which are much lower than the melting point of the fuel sheath. It indicates that the Canadian-SCWR can achieve "no-core-melt" concept under LOCA/LOECC.展开更多
A combined conduction and radiation heat transfer model was used to simulate the heat transfer within wafer and investigate the effect of thermal transport properties on temperature non-uniformity within wafer surface...A combined conduction and radiation heat transfer model was used to simulate the heat transfer within wafer and investigate the effect of thermal transport properties on temperature non-uniformity within wafer surface. It is found that the increased conductivities in both doped and undoped regions help reduce the temperature difference across the wafer surface. However, the doped layer conductivity has little effect on the overall temperature distribution and difference. The temperature level and difference on the top surface drop suddenly when absorption coefficient changes from 104 to 103 m-1. When the absorption coefficient is less or equal to 103 m-1, the temperature level and difference do not change much. The emissivity has the dominant effect on the top surface temperature level and difference. Higher surface emissivity can easily increase the temperature level of the wafer surface. After using the improved property data, the overall temperature level reduces by about 200 K from the basis case. The results will help improve the current understanding of the energy transport in the rapid thermal processing and the wafer temperature monitor and control level.展开更多
We simulated the heat transfer phenomena of the heating module that is primarily based on the radiant energy in the near-infra-red(NIR) domain.In the module,the power emitted by the lamp filament is distributed to the...We simulated the heat transfer phenomena of the heating module that is primarily based on the radiant energy in the near-infra-red(NIR) domain.In the module,the power emitted by the lamp filament is distributed to the lamp glass,reflector,and the target medium,which are cooled by an air flow.The radiant heat transfer is simulated by using the ray-tracing scheme,in which the spectral characteristics of the emission and the materials are incorporated.The heat transport from the lamp glass to the cooling air is analyzed by using the finite volume method.As the lamp-filament temperature rises in the range of 3000-3400K,the NIR radiant power on the target medium increases.However,the lamp-glass temperature also rises,and the proportion of the NIR power to the entire radiation has a peak in the temperature range.The spectral distributions of the absorbed energies in all the components in the module are highly non-uniform,and a monochromatic model of the radiant heat transfer may result in a significant discrepancy.展开更多
基金financially supported by the Program for New Century Excellent Talents in University(No.NCET-13-0229,NCET-09-0396)the National Science & Technology Key Projects of Numerical Control(No.2012ZX04010-031,2012ZX0412-011)the National High Technology Research and Development Program("863"Program)of China(No.2013031003)
文摘For the sake of a more accurate shell boundary and calculation of radiation heat transfer in the Directional Solidification(DS) process, a radiation heat transfer model based on the Finite Element Method(FEM)is developed in this study. Key technologies, such as distinguishing boundaries automatically, local matrix and lumped heat capacity matrix, are also stated. In order to analyze the effect of withdrawing rate on DS process,the solidification processes of a complex superalloy turbine blade in the High Rate Solidification(HRS) process with different withdrawing rates are simulated; and by comparing the simulation results, it is found that the most suitable withdrawing rate is determined to be 5.0 mm·min^(-1). Finally, the accuracy and reliability of the radiation heat transfer model are verified, because of the accordance of simulation results with practical process.
基金Supported by the Doctoral Program of Higher Education of China(No.20120201110043)Atomic Energy of Canada Limited(AECL)
文摘The safety analysis code SCTRAN for SCWR(Super Critical Water Reactor) is modified to own the capability to assess the radiation heat transfer with developing a two-dimensional heat conduction solution scheme and incorporating a radiation heat transfer model. The verification of the developed radiation heat transfer model is conducted through code-to-code comparison with CATHENA. The results show that the modified SCTRAN code is successful for that the maximum absolute error and relative error of the surface temperature between results of SCTRAN and CATHENA are 6.1°C and 0.9%, which are acceptable in temperature prediction. Then,with the modified SCTRAN code, the loss of coolant accident with a total loss of emergency core cooling system(LOCA/LOECC) of Canadian-SCWR is carried out to evaluate its "no-core-melt" concept. The following conclusions are achieved: 1) in the process of LOCA, the decay heat can be totally removed by the radiation heat transfer and the natural convection of the high-temperature coolant, even without an intervention of ECCS(Emergency Core Cooling System); 2) The peak cladding temperature of the fuel pins in the inner and outer rings of the high power group are 1236°C and 1177°C respectively, which are much lower than the melting point of the fuel sheath. It indicates that the Canadian-SCWR can achieve "no-core-melt" concept under LOCA/LOECC.
基金Project(N110204015)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2012M510075)supported by the China Postdoctoral Science Foundation
文摘A combined conduction and radiation heat transfer model was used to simulate the heat transfer within wafer and investigate the effect of thermal transport properties on temperature non-uniformity within wafer surface. It is found that the increased conductivities in both doped and undoped regions help reduce the temperature difference across the wafer surface. However, the doped layer conductivity has little effect on the overall temperature distribution and difference. The temperature level and difference on the top surface drop suddenly when absorption coefficient changes from 104 to 103 m-1. When the absorption coefficient is less or equal to 103 m-1, the temperature level and difference do not change much. The emissivity has the dominant effect on the top surface temperature level and difference. Higher surface emissivity can easily increase the temperature level of the wafer surface. After using the improved property data, the overall temperature level reduces by about 200 K from the basis case. The results will help improve the current understanding of the energy transport in the rapid thermal processing and the wafer temperature monitor and control level.
基金supported by the Korea Research Foundation Grant funded by the Korean Government(MOEHRD,Basic ResearchPromotion Fund)(KRF-2008-331-D00076)
文摘We simulated the heat transfer phenomena of the heating module that is primarily based on the radiant energy in the near-infra-red(NIR) domain.In the module,the power emitted by the lamp filament is distributed to the lamp glass,reflector,and the target medium,which are cooled by an air flow.The radiant heat transfer is simulated by using the ray-tracing scheme,in which the spectral characteristics of the emission and the materials are incorporated.The heat transport from the lamp glass to the cooling air is analyzed by using the finite volume method.As the lamp-filament temperature rises in the range of 3000-3400K,the NIR radiant power on the target medium increases.However,the lamp-glass temperature also rises,and the proportion of the NIR power to the entire radiation has a peak in the temperature range.The spectral distributions of the absorbed energies in all the components in the module are highly non-uniform,and a monochromatic model of the radiant heat transfer may result in a significant discrepancy.
