Contrastive research of condensation-heat-transfer and water-recovery performance on 10-nm ceramic membrane tube and stainless steel tube

摘要

As a new type of condensation-heat-transfer facility, nano-porous ceramic membrane tube is surrounded by nano-porous wall surface, which is hydrophilic to capture the vapor or condensate. In general, water vapor will condense into liquid near the wall surface or inside its nano-sized pores, wherein its latent heat will be released synchronously. Thus, an amount of heat and water can be recovered by using nano-porous ceramic membrane tube. Experiments are performed using a 10-nm ceramic membrane tube and a traditional condensation-heat-transfer tube (a 304 stainless steel tube in the experiment) with the same dimensions. The gas mixture consisting of nitrogen (N-2) and water vapor is employed as working fluid, and the low-temperature water is used as the cold source. Great attention is paid to contrastively evaluate the heat-transfer and water-recovery performance of two kinds of tubes at different influential parameters (e.g., inclination angle). Compared with stainless steel tube, ceramic membrane tube has a more outstanding heat-transfer characteristic; it can enhance the cooling water temperature by 125% maximally. In addition, condensation-heat-transfer process of 10-nm ceramic membrane tube is influenced by inclination angle more significantly. In the 10-nm ceramic membrane tube, it has highest condensation-heat-transfer coefficient at horizontal flow (theta = 0 degrees) and lowest at vertical down flow (theta = - 90 degrees). Finally, water-recovery mass flux in the 10-nm ceramic membrane tube is higher than that in stainless steel tube, especially for the transmembrane pressure difference is higher than 3.83 kPa. This paper is useful for ceramic membrane condenser arrangement and design.