Asphalt mixture pavement reheating is one of the important steps in hot in-place recycling(HIR).To improve the heating speed of asphalt pavement in HIR,based on the numerical analysis model of asphalt mixture heating ...Asphalt mixture pavement reheating is one of the important steps in hot in-place recycling(HIR).To improve the heating speed of asphalt pavement in HIR,based on the numerical analysis model of asphalt mixture heating process,a new multi-layer low-temperature heating method(MLHM)was proposed.Considering input heat flux,the thermal capacity and thermal resistance of asphalt mixture,the heat transfer model was established based on energy conservation law.By heating the asphalt mixture in layers,it changes the situation that the heat energy can only be input from the upper surface of the asphalt mixture pavement.Through the simulation of the heating method of asphalt mixture in the existing technology,the result shows that the existing heating methods lead to serious aging or charring of the asphalt mixture.By MLHM,the upper and the bottom of the asphalt mixture are heated at the same time,and the heating temperature is lower than other heat methods,which not only reduces the heating thickness and increases the heating area of the asphalt mixture pavement,but also improves the heating speed,saves the energy resource and ensures the heating quality.Especially,by MLHM,the heating uniformity is better and speed is faster.展开更多
Investigations into critical beat flux at low flow and pressure conditions are of particular interest when predicting the nuclear reactor core behavior during Loss of Coolant accident （LOCA）. Therefore, critical hea...Investigations into critical beat flux at low flow and pressure conditions are of particular interest when predicting the nuclear reactor core behavior during Loss of Coolant accident （LOCA）. Therefore, critical heat flux （CHF） has been investigated in a uniformly heated vertical round tube at two low system pressures and six low water flowrates. The results have been compared with two correlations which have different approaches and CHF look-up table. Good agreements have been obtained for the three comparisons at the lower sets of mass fluxes. The Bowring correlation was found to be the best to correlate the experimental results with Root Mean Square Error RMSE of 0.54% and 0.56% for the 5 bar and 15 bar system pressure respectively. A comparisons with the Shim and Lee correlation yielded RMSE of 0.23% and 5.74% for the two system pressure respectively. When the look-up table of Groeneveld et al. was used, RMES of 0.55% and 25.2% was obtained for the two system pressure respectively.展开更多
The goal of this article is to study numerically the mixed convection in a differentially heated rid-driven cavity with non-uniform heating of the bottom wall. The velocity field is solved by a hybrid scheme with mult...The goal of this article is to study numerically the mixed convection in a differentially heated rid-driven cavity with non-uniform heating of the bottom wall. The velocity field is solved by a hybrid scheme with multiple relaxation time Lattice Boltzmann （MRT-LBM） model, while the temperature field is obtained by resolution of the energy balance equation using the finite difference method （FDM）. First, the model is checked and validated using data from the riterature. Validation of the present resuJts with those available in the literature shows a good agreement. A good efficiency in time simulation is confirmed. Thereafter, the model has been applied to mixed convection in a driven cavity with non-uniform heating wall at the fixed Grashof number Gr = 106. It is found that, the heat transfer is weakened as the Richardson number is augmented. For Gr = 106, we note the appearance of secondary vortices at different positions of the cavity corners.展开更多
基金Project(2017JM5077)supported by the Natural Science Basic Research Plan in Shaanxi Province,ChinaProjects(300102259109,300102259306)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Asphalt mixture pavement reheating is one of the important steps in hot in-place recycling(HIR).To improve the heating speed of asphalt pavement in HIR,based on the numerical analysis model of asphalt mixture heating process,a new multi-layer low-temperature heating method(MLHM)was proposed.Considering input heat flux,the thermal capacity and thermal resistance of asphalt mixture,the heat transfer model was established based on energy conservation law.By heating the asphalt mixture in layers,it changes the situation that the heat energy can only be input from the upper surface of the asphalt mixture pavement.Through the simulation of the heating method of asphalt mixture in the existing technology,the result shows that the existing heating methods lead to serious aging or charring of the asphalt mixture.By MLHM,the upper and the bottom of the asphalt mixture are heated at the same time,and the heating temperature is lower than other heat methods,which not only reduces the heating thickness and increases the heating area of the asphalt mixture pavement,but also improves the heating speed,saves the energy resource and ensures the heating quality.Especially,by MLHM,the heating uniformity is better and speed is faster.
文摘Investigations into critical beat flux at low flow and pressure conditions are of particular interest when predicting the nuclear reactor core behavior during Loss of Coolant accident （LOCA）. Therefore, critical heat flux （CHF） has been investigated in a uniformly heated vertical round tube at two low system pressures and six low water flowrates. The results have been compared with two correlations which have different approaches and CHF look-up table. Good agreements have been obtained for the three comparisons at the lower sets of mass fluxes. The Bowring correlation was found to be the best to correlate the experimental results with Root Mean Square Error RMSE of 0.54% and 0.56% for the 5 bar and 15 bar system pressure respectively. A comparisons with the Shim and Lee correlation yielded RMSE of 0.23% and 5.74% for the two system pressure respectively. When the look-up table of Groeneveld et al. was used, RMES of 0.55% and 25.2% was obtained for the two system pressure respectively.
文摘The goal of this article is to study numerically the mixed convection in a differentially heated rid-driven cavity with non-uniform heating of the bottom wall. The velocity field is solved by a hybrid scheme with multiple relaxation time Lattice Boltzmann （MRT-LBM） model, while the temperature field is obtained by resolution of the energy balance equation using the finite difference method （FDM）. First, the model is checked and validated using data from the riterature. Validation of the present resuJts with those available in the literature shows a good agreement. A good efficiency in time simulation is confirmed. Thereafter, the model has been applied to mixed convection in a driven cavity with non-uniform heating wall at the fixed Grashof number Gr = 106. It is found that, the heat transfer is weakened as the Richardson number is augmented. For Gr = 106, we note the appearance of secondary vortices at different positions of the cavity corners.
