EXPERIMENTAL STUDY ON LAMINAR FLOW RESISTANCE CHARACTERISTICS OF FLAT TUBE AND MICROFINNED FLAT TUBE

In this paper, the hydraulic performance of single-phase water inside a novel microfinned flat tube is experimentally investigated with the Reynolds number less than 4000. The effects of fin geometrical parameters and section aspect ratio on the pressure drop of the microfinned flat tube are studied, and results show that the pressure drop would significantly increase compared to the smooth tubes due to the fluid in the flat tube has higher flow velocity for the same Reynolds number. However, compared with the flat tube, the microfinned flat tube performs with slightly higher pressure drop, which can be explained by the increase of the wall roughness. Based on aforementioned characteristics, a new correlation of single-phase friction factor for the fl at tubes has been developed. At the same time, the correlation that described the friction factor of the microfinned flat tube is proposed according to the empirical correction of the flat tube with a reasonable correction. The uncertainty and error of the correlation are analyzed, which can predict the experimental data with the deviation less than 10%.