Parameter optimization integrating operation parameters and structure parameters for the purpose of high permeate flux,high productivity and low exergy consumption of direct contact membrane distillation (DCMD) proces...Parameter optimization integrating operation parameters and structure parameters for the purpose of high permeate flux,high productivity and low exergy consumption of direct contact membrane distillation (DCMD) process was conducted based on Taguchi experimental design. L16(45) orthogonal experiments were carried out with feed inlet temperature,permeate stream inlet temperature,flow rate,module packing density and length-diameter ratio as optimization parameters and with permeate flux,water productivity per unit volume of module and water production per unit exergy loss separately as optimization objectives. By using range analysis method,the dominance degree of the various influencing factors for the three objectives was analyzed and the optimum condition was obtained for the three objectives separately. Furthermore,the multi-objectives optimization was performed based on a weight grade method. The combined optimum conditions are feed inlet temperature 75℃,packing density 30% ,length-diameter ratio 10,permeate stream inlet temperature 30 ℃ and flow rate 25 L/h,which is in order of their dominance degree,and the validity of the optimization scheme was confirmed.展开更多
投弃式海流剖面仪(Expendable Current Profiler,XCP)周围流场是典型的旋转圆柱绕流。探头周围流场对探头的运动状态起决定性作用,这直接关系到探头的测量性能,因此有必要对旋转圆柱周围流场进行实验研究。实验在循环水槽中进行,通过PI...投弃式海流剖面仪(Expendable Current Profiler,XCP)周围流场是典型的旋转圆柱绕流。探头周围流场对探头的运动状态起决定性作用,这直接关系到探头的测量性能,因此有必要对旋转圆柱周围流场进行实验研究。实验在循环水槽中进行,通过PIV对雷诺数保持不变(Re=1000)、不同圆柱旋转速度比(α=0、0.5、1.0、1.5、2.0、2.5、3.0、3.5、4.0、4.5和5.0)的圆柱下游尾流场进行研究。通过选取不同旋转速度比的任一时刻的瞬态流场,来分析旋转对圆柱尾流结构的影响。为了获得流场的频率信息,对所获得流场信息进行能谱分析来获取涡旋的脱落频率,并进一步使用正交模态分解对流场进行分析,给出了流场主要拟序结构及其能量与转速比的变化趋势。发现圆柱旋转改变圆柱尾流结构,使尾迹尺度变小。在旋转速度比0≤α≤2.0时,存在明显的周期性涡旋脱落,并且涡旋脱落的频率有逐渐升高的趋势;而且当转速比2.0<α≤5.0时尾迹流场的周期性减弱,涡旋脱落变得不明显,流场表现出低频、剪切层的区域特征。随着转速变大,涡旋尺度变小。在较高旋转速度比时,流场中能量被重新分布。展开更多
文摘Parameter optimization integrating operation parameters and structure parameters for the purpose of high permeate flux,high productivity and low exergy consumption of direct contact membrane distillation (DCMD) process was conducted based on Taguchi experimental design. L16(45) orthogonal experiments were carried out with feed inlet temperature,permeate stream inlet temperature,flow rate,module packing density and length-diameter ratio as optimization parameters and with permeate flux,water productivity per unit volume of module and water production per unit exergy loss separately as optimization objectives. By using range analysis method,the dominance degree of the various influencing factors for the three objectives was analyzed and the optimum condition was obtained for the three objectives separately. Furthermore,the multi-objectives optimization was performed based on a weight grade method. The combined optimum conditions are feed inlet temperature 75℃,packing density 30% ,length-diameter ratio 10,permeate stream inlet temperature 30 ℃ and flow rate 25 L/h,which is in order of their dominance degree,and the validity of the optimization scheme was confirmed.
文摘投弃式海流剖面仪(Expendable Current Profiler,XCP)周围流场是典型的旋转圆柱绕流。探头周围流场对探头的运动状态起决定性作用,这直接关系到探头的测量性能,因此有必要对旋转圆柱周围流场进行实验研究。实验在循环水槽中进行,通过PIV对雷诺数保持不变(Re=1000)、不同圆柱旋转速度比(α=0、0.5、1.0、1.5、2.0、2.5、3.0、3.5、4.0、4.5和5.0)的圆柱下游尾流场进行研究。通过选取不同旋转速度比的任一时刻的瞬态流场,来分析旋转对圆柱尾流结构的影响。为了获得流场的频率信息,对所获得流场信息进行能谱分析来获取涡旋的脱落频率,并进一步使用正交模态分解对流场进行分析,给出了流场主要拟序结构及其能量与转速比的变化趋势。发现圆柱旋转改变圆柱尾流结构,使尾迹尺度变小。在旋转速度比0≤α≤2.0时,存在明显的周期性涡旋脱落,并且涡旋脱落的频率有逐渐升高的趋势;而且当转速比2.0<α≤5.0时尾迹流场的周期性减弱,涡旋脱落变得不明显,流场表现出低频、剪切层的区域特征。随着转速变大,涡旋尺度变小。在较高旋转速度比时,流场中能量被重新分布。
