新型板框气隙式膜蒸馏组件流场的CFD数值模拟

CFD numerical simulation of the flow field of module in the new frame and air gap membrane distillation

利用计算流体力学(CFD)软件,构造三维计算模型,对新型的热量回收板框气隙式膜蒸馏组件内部热质传递过程进行研究.分别考察了不同进料温度、流速和操作真空度条件下模型内部流体温度分布情况.模拟结果表明:提高进料侧料液流速或者减小渗透侧真空度,在同一位置的膜表面温度均增加;渗透侧换热中空纤维从下至上壁面温度呈现递增的趋势,各层中空纤维外表面温度均存在差异,距离膜侧位置越近,中空纤维表面温度越高.研究发现,在不同条件下渗透侧底部区域的蒸汽温度大于热料液主体温度,不利于膜蒸馏过程和热量回收利用;当增加料液温度或者下游侧真空度时,有效膜蒸馏面积增大.结果揭示了新型组件内部直观的参数分布规律,为内部结构进一步优化奠定了基础.

By using computational fluid dynamics （CFD） software, the three-dimensional calculation model was constructed to research the internal heat and mass transfer progress of the new type of heat recovery of frame and air gap membrane distillation module. The distribution of fluid temperature was examined under the conditions of different feed temperature, feed rate and operating vacuum. The simulation results showed that： the surface temperature of membrane was increased by improving feed rate or decreasing vacuum degree of permeability side; Outer surface temperature of heat-transfer hollow fiber by side of the permeability showed the tendency was increasing from the bottom. The outer surface temperature of each hollow fiber existed differences, the higher outer surface temperature of hollow fiber, the closer distance to the side of membrane. The steam temperature of the bottom of side of the permeability was higher than main temperature of the hot feed liquid, which was not conducive to membrane distillation process. The effective area of membrane distillation would be increased which elevates temperature or vacuum degree. This study reveals internal intuitive parameters distribution law of the new component, which laid a foundation for further optimization of the internal structure.