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...