摘要
提出了一种测定膜蒸馏过程传热系数的新方法,即考察NaCl和KCl水溶液膜蒸馏浓缩过程中的通量变化,利用膜表面结晶导致通量急剧下降这一现象间接确定料液侧膜表面的温度,从而由模型方程计算传热系数。通过不同流速下的膜蒸馏实验结果,拟合出了传热系数关联式,其中雷诺准数指数为0.8,与Dittus-Boelter公式一致;在此基础上求出膜蒸馏系数,其平均值5.5×10-7kg/(m2.s.Pa),与文献报道接近;以实验确定的模型参数预测纯水膜蒸馏通量,实验值与预测值吻合较好。这些都说明了本文提出方法的有效性。
A new method to determine the heat transfer coefficient of the thermal boundary layer in membrane distillation （MD） is presented. By measuring the trans-membrane mass flux and feed concentration while condensing an aqueous solution of NaCl and KCl, the critical values and the corresponding feed temperature at the membrane surface can be found at the point when crystallization occurs on the membrane surface, and thus the heat transfer coefficient can be determined. The experiments were conducted at different feed velocities, and the results were used to build a correlation of heat transfer. The correlation was utilized to calculate the membrane distillation coefficient and to predict the mass flux of pure water MD. The results show good agreement with experiment, indicating that the method is effective for the calculation of heat transfer coefficients in MD processes.
出处
《北京化工大学学报（自然科学版）》
CAS
CSCD
北大核心
2007年第2期130-133,共4页
Journal of Beijing University of Chemical Technology(Natural Science Edition)
基金
国家自然科学基金(20206003)
关键词
膜蒸馏
结晶
传热系数
膜蒸馏系数
membrane distillation
crystallization
heat transfer coefficient
membrane distillation coefficient
