BETA磨是工业矿物加工中的关键设备。它的性能直接影响生产效率和能耗。利用离散元法(Discrete Element Method,DEM)分析BETA磨的单位时间进料量、动辊转速、辊轮间距、辊轮直径与长度等工作参数,得到最优组合参数,以提高破碎效率并降...BETA磨是工业矿物加工中的关键设备。它的性能直接影响生产效率和能耗。利用离散元法(Discrete Element Method,DEM)分析BETA磨的单位时间进料量、动辊转速、辊轮间距、辊轮直径与长度等工作参数,得到最优组合参数,以提高破碎效率并降低能耗。研究建立了BETA磨的DEM模型,通过仿真破碎过程,确定了各单因素对破碎效率的影响。通过分析不同参数组合下的破碎能,得出了多因素的最优参数组合,可为BETA磨的设计和操作提供选择依据。展开更多
Taking the ratio of heat transfer area to net power and heat recovery efficiency into account, a multi-objective mathematical model was developed for organic Rankine cycle （ORC）. Working fluids considered were R123,...Taking the ratio of heat transfer area to net power and heat recovery efficiency into account, a multi-objective mathematical model was developed for organic Rankine cycle （ORC）. Working fluids considered were R123, R134a, R141b, R227ea and R245fa. Under the given conditions, the parameters including evaporating and condensing pressures, working fluid and cooling water velocities were optimized by simulated annealing algorithm. The results show that the optimal evaporating pressure increases with the heat source temperature increasing. Compared with other working fluids, R123 is the best choice for the temperature range of 100--180℃ and R141 b shows better performance when the temperature is higher than 180 ℃. Economic characteristic of system decreases rapidly with the decrease of heat source temperature. ORC system is uneconomical for the heat source temperature lower than 100℃.展开更多
Unlike other types of renewable energy resources, geothermal energy provides a stable source of energy as it can be exploited regardless of meteorological conditions. Using organic cycle, geothermal energy can be util...Unlike other types of renewable energy resources, geothermal energy provides a stable source of energy as it can be exploited regardless of meteorological conditions. Using organic cycle, geothermal energy can be utilized for power generation. In such systems, the heat is exchanged between the surrounding rock mass and transport fluid. Consequently, the temperature of extracted geofluid from the well decreases with the time in accordance with the working parameters. Those parameters includeenergy extraction rate, temperature difference between inlet and outlet of the well, and the thermal conductivity of the ground. Current work, aims to develop a reliable computer model to specify the optimal working parameters so that the geofluid temperature will not reach a low value that is not acceptable for electricity generation, and the energy availability of geothermal resource is maximized. In the current study the ground thermal properties, the geothermal gradient and well dimensions are based on realistic data in Qatar and neighboring countries. The proposed model was developed for different heat extraction rate, different ground thermal properties, and for varied temperature difference between inlet and outlet of the well. Simulation shows that selecting the optimal working parameters can increase the availability of geothermal resource significantly.展开更多
文摘BETA磨是工业矿物加工中的关键设备。它的性能直接影响生产效率和能耗。利用离散元法(Discrete Element Method,DEM)分析BETA磨的单位时间进料量、动辊转速、辊轮间距、辊轮直径与长度等工作参数,得到最优组合参数,以提高破碎效率并降低能耗。研究建立了BETA磨的DEM模型,通过仿真破碎过程,确定了各单因素对破碎效率的影响。通过分析不同参数组合下的破碎能,得出了多因素的最优参数组合,可为BETA磨的设计和操作提供选择依据。
基金Project(2009GK2009) supported by Science and Technology Department Funds of Hunan Province,ChinaProject(08C26224302178) supported by Innovation Fund for Technology Based Firms of China
文摘Taking the ratio of heat transfer area to net power and heat recovery efficiency into account, a multi-objective mathematical model was developed for organic Rankine cycle （ORC）. Working fluids considered were R123, R134a, R141b, R227ea and R245fa. Under the given conditions, the parameters including evaporating and condensing pressures, working fluid and cooling water velocities were optimized by simulated annealing algorithm. The results show that the optimal evaporating pressure increases with the heat source temperature increasing. Compared with other working fluids, R123 is the best choice for the temperature range of 100--180℃ and R141 b shows better performance when the temperature is higher than 180 ℃. Economic characteristic of system decreases rapidly with the decrease of heat source temperature. ORC system is uneconomical for the heat source temperature lower than 100℃.
文摘Unlike other types of renewable energy resources, geothermal energy provides a stable source of energy as it can be exploited regardless of meteorological conditions. Using organic cycle, geothermal energy can be utilized for power generation. In such systems, the heat is exchanged between the surrounding rock mass and transport fluid. Consequently, the temperature of extracted geofluid from the well decreases with the time in accordance with the working parameters. Those parameters includeenergy extraction rate, temperature difference between inlet and outlet of the well, and the thermal conductivity of the ground. Current work, aims to develop a reliable computer model to specify the optimal working parameters so that the geofluid temperature will not reach a low value that is not acceptable for electricity generation, and the energy availability of geothermal resource is maximized. In the current study the ground thermal properties, the geothermal gradient and well dimensions are based on realistic data in Qatar and neighboring countries. The proposed model was developed for different heat extraction rate, different ground thermal properties, and for varied temperature difference between inlet and outlet of the well. Simulation shows that selecting the optimal working parameters can increase the availability of geothermal resource significantly.
