An Experimental Study of Condensate Retention on the Air Side of Flat-Tube Heat Exchangers

Condensate on the air-side surface of flat-tube air-cooling heat exchangers can result in several adverse effects on the overall thermal hydraulic performance. In order to enhance the performance of compact heat exchangers under wet-surface conditions, promoting the drainage of condensed water is critical. Drainage channels on tube walls might provide a robust solution to promote condensate drainage from compact heat exchangers. A quantitative and qualitative evaluation of the effectiveness of drainage channels on the condensate retention characteristics of compact flat-tube louver-fin heat exchangers is presented. Various geometries of drainage channels are engraved on the surrogate tubes in contact with fin stock. Two fin designs are tested using dynamic dip testing method and a small wind tunnel. The data from the quantitative results and the visualization tests clearly show that the drainage channels reduce the condensate retention for one of the fin designs. The results also provide a comparison between drainage channels based on their geometry and dimensions.