The Two-phase Flow And Boiling Heat Transfer In 3-D Micro-fin Helical Tube

At present, the study of water in smooth helical tube, of which the main work is about critical heat flux (CHF), is the primary concern of the research about the two-phase flow and heat transfer in curved pipe. However, the study of refrigerant in micro-fin helical tube has rarely been reported. Therefore, it will have important academic significance and engineering application value to do experimental research of R134a with the aid of the heat transfer enhancement technique which combines micro-fin with secondary flow and to analyze the boiling heat transfer enhancement theory in a helical tube with micro-fined inner side. The main works and conclusions in this paper are as follows:1, The two-phase flow patterns are observed in micro-fin helical tube. The flow pattern map is obtained and compared with the map of smooth straight tube, the result of which explains the theory of transformation among the flow patterns in micro-fin helical tube and the pattern difference between helical and straight tube.2, The two-phase flow heat transfer capability is tested and compared with the smooth helical tube. At mass flux between 79kg/(m2s) and 315kg/(m2s) and heat flux between 11.0kw/m2 and 20.0kw/m2, the heat transfer enhancement ratio is from 1.5 to 2.1.3, The single-phase laminar flow and heat transfer has been calculated by different discredited scheme in helical tube and the results are very in accord with the obtained experimental data.4, The experimental research of water in the carbon-iron heat pipe with 3-D micro-fin is performed and offered the experimental data for engineering application.