This work investigates the proportion of generated fines in a pilot-scale experiment using a belt conveyor and commercial fuel pellets.For this,a belt conveyor with a length of 3.1 m was used and operated at varying c...This work investigates the proportion of generated fines in a pilot-scale experiment using a belt conveyor and commercial fuel pellets.For this,a belt conveyor with a length of 3.1 m was used and operated at varying conditions:speeds,percentages of material loading on the belt,two combinations of the inclination angle of the belt and the falling height,and a different number of handling steps.We considered a design of experiments approach based on response surface methodology to investigate the effect of different conditions on the potential of fines generation.Moreover,a comparison between the results of the belt conveyor and three common benchmark experimental approaches(tumbling box,rotary impact tester,and mechanical compression test)was made.Results show that the number of handling steps and the combined effect of drop height and inclination angle directly affected the fines generation.However,the tested belt speed range and the level of loading were of lower significance.A polynomial quadratic model was derived based on the regression analysis and showed a high accuracy to predict the proportion of fines.Moreover,the tumbling box method showed good potential to predict the proportion of fines in a belt conveyor when transported several times.展开更多
For an analysis of the oxidation behavior of UO2 nuclear fuel pellet under a loss of water coolant accident in a spent nuclear fuel pool of an LWR, thermodynamic assessments of UO2 oxidation were carried out under var...For an analysis of the oxidation behavior of UO2 nuclear fuel pellet under a loss of water coolant accident in a spent nuclear fuel pool of an LWR, thermodynamic assessments of UO2 oxidation were carried out under various atmospheric conditions. In a steam atmosphere, it was assessed that UO2 would not be fully oxidized into U3O8 due to the relatively lower oxygen partial pressure, while UO2 will be fully oxidized into U3O8 in an air atmosphere. In an air and steam mixture atmosphere, the UO2 oxidation was dominantly affected by the air volumetric fraction, because of the relatively higher oxygen partial pressure of air. In addition, the effect of H2 volumetric fraction on the oxygen partial pressure under a mixture atmosphere was calculated, and it was revealed that UO2 pellet oxidation could be reduced above the critical value of H2 volumetric fraction.展开更多
Based on the two-dimensional kinetic ablation theory of the hydrogen pellet ablation developed by Kuteev [B.V. Kuteev, Nuclear Fusion, 35 (1995) 431], an algorithm of erosion speed and ablation rate calculations for L...Based on the two-dimensional kinetic ablation theory of the hydrogen pellet ablation developed by Kuteev [B.V. Kuteev, Nuclear Fusion, 35 (1995) 431], an algorithm of erosion speed and ablation rate calculations for Li, Be, and B impurity pellets in reactor-relevant plasma has been derived. Results show compatibilities of lithium pellet injection used in α-particle diagnostics are positive in comparison with other solid impurity pellets (e.g. Be, B and C). Using the 2-D Kuteev lentil model, including kinetic effects, we find that currently existing pellet injection techniques will not meet core-fueling requirements for ITER-FEAT. A pressure as high as 254 MPa must be applied to a pellet accelerator with a 200 cm-long single-stage pneumatic gun, in order to accelerate a pellet with a radius rpo = 0.5 cm to a velocity of vpo, 24 × 105 cm/s penetrating 100 cm into the ITER plasma core. Comparisons of pellet velocity- and radius-dependent penetration depth between the Neutral Gas Shielding and the Kuteev's models are made. However, we find that the isotopic effects can lead to a 33% lower pellet speed for solid DT, compared to an identical H2 pellet penetrating the same length in ITER-FEAT plasma, and our calculations show that HFS injection will much improve core fueling efficiency.展开更多
Pellet injection is an attractive technology for core-fueling and magnetohydrodynamic study in magnetic-conflnement fusion devices like tokamaks and stellarators.It can inject solid hydrogen/deuterium pellets into the...Pellet injection is an attractive technology for core-fueling and magnetohydrodynamic study in magnetic-conflnement fusion devices like tokamaks and stellarators.It can inject solid hydrogen/deuterium pellets into the plasma with deeper density deposition compared with other fueling methods,such as gas pufflng.A three-barrel H_(2)pellet injection system was installed on the J-TEXT tokamak and experiments were carried out.The pellets are formed in three barrels cooled by a cryocooler and compressor system at around 9 K,and are 0.8 mm/1 mm diameter and 0.8 mm length.The pellet is launched by helium propellant gas and injected from the lowfleld side of the plasma.The normal range of pellet speed is 210–310 m s^(-1)for different propellant gas pressures.Due to the three-barrel structure,the number of injected pellets can be adjusted between one and three.Pellets can be launched sequentially with arbitrary time intervals,which enables flexible applications.The results of the experiments show that pellet fueling efflciency can reach 50%.The energy conflnement time increased by about 7.5–10 ms after pellet injection.展开更多
为了研究玉米秸秆与木屑及木钠的混配成型特性,该文采用5因素的响应面中心组合设计,在WD-100KE型电子压力机上进行单颗粒压缩试验,研究了成型参数木屑质量分数(0~40)、木钠质量分数(2%~10%)、温度(40~160℃)、水分(4%~20%)、压力(1~9 k...为了研究玉米秸秆与木屑及木钠的混配成型特性,该文采用5因素的响应面中心组合设计,在WD-100KE型电子压力机上进行单颗粒压缩试验,研究了成型参数木屑质量分数(0~40)、木钠质量分数(2%~10%)、温度(40~160℃)、水分(4%~20%)、压力(1~9 k N)对成型指标松弛密度、比能耗、径向最大抗压力的影响。通过对试验数据的回归,建立了响应面模型,分析了参数间的交互作用,获得了较佳的成型参数,并进行了试验验证。结果表明:温度和水分、水分和压力对比能耗起显著交互作用;木钠质量分数和温度、温度和水分、水分和压力对径向最大抗压力起显著交互作用。较佳的参数为:木屑质量分数10.15%,木钠质量分数8%,温度95.83℃,水分15.83%,压力3 k N,验证试验参数修正为:木屑质量分数10%,木钠质量分数8%,温度96℃,水分16%,压力3 k N,响应指标结果为:松弛密度1 054 kg/m3、比能耗8.02 k J/kg、径向最大抗压力685N,与预测值误差值在8%以内,可为相关生产提供理论参考。展开更多
基金The support of the staff at the Wolfson Centre for Bulk Solids Handling Technology of the University of Greenwich to execute the experiments with the rotary impact tester is highly appreciated.We thank Ed Stok,Freek Brakel,Andre van den Bosch,Shreyas Sridhar,and Otto Cramwinckel for their help with the experiments at the Delft University of TechnologyThis work was financially supported by the Top Consortium for Knowledge and Innovation for the Biobased Economy(TKI-BBE),under grant number BBE-1713(Biomassa pellets:degradatie tjdens transport en handling).
文摘This work investigates the proportion of generated fines in a pilot-scale experiment using a belt conveyor and commercial fuel pellets.For this,a belt conveyor with a length of 3.1 m was used and operated at varying conditions:speeds,percentages of material loading on the belt,two combinations of the inclination angle of the belt and the falling height,and a different number of handling steps.We considered a design of experiments approach based on response surface methodology to investigate the effect of different conditions on the potential of fines generation.Moreover,a comparison between the results of the belt conveyor and three common benchmark experimental approaches(tumbling box,rotary impact tester,and mechanical compression test)was made.Results show that the number of handling steps and the combined effect of drop height and inclination angle directly affected the fines generation.However,the tested belt speed range and the level of loading were of lower significance.A polynomial quadratic model was derived based on the regression analysis and showed a high accuracy to predict the proportion of fines.Moreover,the tumbling box method showed good potential to predict the proportion of fines in a belt conveyor when transported several times.
文摘For an analysis of the oxidation behavior of UO2 nuclear fuel pellet under a loss of water coolant accident in a spent nuclear fuel pool of an LWR, thermodynamic assessments of UO2 oxidation were carried out under various atmospheric conditions. In a steam atmosphere, it was assessed that UO2 would not be fully oxidized into U3O8 due to the relatively lower oxygen partial pressure, while UO2 will be fully oxidized into U3O8 in an air atmosphere. In an air and steam mixture atmosphere, the UO2 oxidation was dominantly affected by the air volumetric fraction, because of the relatively higher oxygen partial pressure of air. In addition, the effect of H2 volumetric fraction on the oxygen partial pressure under a mixture atmosphere was calculated, and it was revealed that UO2 pellet oxidation could be reduced above the critical value of H2 volumetric fraction.
文摘Based on the two-dimensional kinetic ablation theory of the hydrogen pellet ablation developed by Kuteev [B.V. Kuteev, Nuclear Fusion, 35 (1995) 431], an algorithm of erosion speed and ablation rate calculations for Li, Be, and B impurity pellets in reactor-relevant plasma has been derived. Results show compatibilities of lithium pellet injection used in α-particle diagnostics are positive in comparison with other solid impurity pellets (e.g. Be, B and C). Using the 2-D Kuteev lentil model, including kinetic effects, we find that currently existing pellet injection techniques will not meet core-fueling requirements for ITER-FEAT. A pressure as high as 254 MPa must be applied to a pellet accelerator with a 200 cm-long single-stage pneumatic gun, in order to accelerate a pellet with a radius rpo = 0.5 cm to a velocity of vpo, 24 × 105 cm/s penetrating 100 cm into the ITER plasma core. Comparisons of pellet velocity- and radius-dependent penetration depth between the Neutral Gas Shielding and the Kuteev's models are made. However, we find that the isotopic effects can lead to a 33% lower pellet speed for solid DT, compared to an identical H2 pellet penetrating the same length in ITER-FEAT plasma, and our calculations show that HFS injection will much improve core fueling efficiency.
基金supported by the National MCF Energy R&D Program of China(No.2019YFE03010004)the National Key R&D Program of China(Nos.2018YFE0309100 and 2017YFE0302000)+1 种基金the National Magnetic Conflnement Fusion Science Program(Nos.2015GB111002 and 2015GB104000)National Natural Science Foundation of China(Nos.11775089,11905077,51821005 and 11575068)。
文摘Pellet injection is an attractive technology for core-fueling and magnetohydrodynamic study in magnetic-conflnement fusion devices like tokamaks and stellarators.It can inject solid hydrogen/deuterium pellets into the plasma with deeper density deposition compared with other fueling methods,such as gas pufflng.A three-barrel H_(2)pellet injection system was installed on the J-TEXT tokamak and experiments were carried out.The pellets are formed in three barrels cooled by a cryocooler and compressor system at around 9 K,and are 0.8 mm/1 mm diameter and 0.8 mm length.The pellet is launched by helium propellant gas and injected from the lowfleld side of the plasma.The normal range of pellet speed is 210–310 m s^(-1)for different propellant gas pressures.Due to the three-barrel structure,the number of injected pellets can be adjusted between one and three.Pellets can be launched sequentially with arbitrary time intervals,which enables flexible applications.The results of the experiments show that pellet fueling efflciency can reach 50%.The energy conflnement time increased by about 7.5–10 ms after pellet injection.
文摘为了研究玉米秸秆与木屑及木钠的混配成型特性,该文采用5因素的响应面中心组合设计,在WD-100KE型电子压力机上进行单颗粒压缩试验,研究了成型参数木屑质量分数(0~40)、木钠质量分数(2%~10%)、温度(40~160℃)、水分(4%~20%)、压力(1~9 k N)对成型指标松弛密度、比能耗、径向最大抗压力的影响。通过对试验数据的回归,建立了响应面模型,分析了参数间的交互作用,获得了较佳的成型参数,并进行了试验验证。结果表明:温度和水分、水分和压力对比能耗起显著交互作用;木钠质量分数和温度、温度和水分、水分和压力对径向最大抗压力起显著交互作用。较佳的参数为:木屑质量分数10.15%,木钠质量分数8%,温度95.83℃,水分15.83%,压力3 k N,验证试验参数修正为:木屑质量分数10%,木钠质量分数8%,温度96℃,水分16%,压力3 k N,响应指标结果为:松弛密度1 054 kg/m3、比能耗8.02 k J/kg、径向最大抗压力685N,与预测值误差值在8%以内,可为相关生产提供理论参考。
