摘要
将直接接触式膜蒸馏的概念和操作过程引入到换热器的设计中,提出了一种既有传热又有传质的新型中空纤维膜换热器.以水为工作介质,对采用聚偏氟乙烯膜(PVDF)的中空纤维膜换热器进行了初步的传热、传质实验研究,考察了逆流布置下溶液的进口温度和流量对换热器的传热、传质效果的影响,并构建了同样尺寸的铜列管式换热器进行对比研究.实验和理论结果表明,虽然膜材料本身的热传导系数较低,但膜换热器冷热流体之间接触面积比传统换热器大,特别是水蒸气从热侧向冷侧进行质量传递的同时还进行潜热传递,因此膜换热器的换热量可维持在较高水平,流体的进出口温差也有大幅度提高.初步研究结果显示,在实验的工况范围内,在低流速、小流量下,膜换热器的传热性能优于金属换热器,但随着管内流速的增加,膜换热器的沿程阻力将远大于金属换热器,因此膜换热器适合于在低流速的情况下使用.
An experiment on heat and mass transfer of a hollow fiber membrane heat exchanger proposed in our study was conducted with water as a working medium and Poly（vinylidene fluoride） （PDVF） as a membrane material. The influence of inlet temperature and flow rate of the solution on heat and mass transfer of the heat exchanger was explored under the counter flow condition. Moreover, a brass shell-and-tube heat exchanger with the same size as the membrane one was fabricated to compare its heat transfer, pressure drop and other character istics with those of the membrane heat exchanger. The experimental and theoretical studies indicate that although the thermal conductivity of the membrane materials is lower, the heat transfer capability of the membrane heat exchanger is higher due to its larger contact surface between the hot fluid and cold fluid, especially, the latent heat of the vapor caused by the mass transfer from the hot side to the cold side. The experimental result shows that the performance of the membrane heat exchanger is better than that of the metal one at the low flow rate under the experimental operation conditions. However, when the flow velocity in the tubes increases, the frictional resistance in the membrane heat exchanger is far larger than that in the metal heat exchanger. It seems that the present heat exchanger could be applied under low flow rate conditions.
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2009年第5期40-45,共6页
Journal of Xi'an Jiaotong University
基金
陕西省科技研究发展计划资助项目(2005K05-G17)
关键词
中空纤维膜
换热器
膜蒸馏
余热回收
hollow membrane
heat exchanger
membrane distillation
waste heat recovery
