Abstract: By modifying the energy equation of finite volume of liquid flow, the viewpoint of heat conveyance is presented under the assumption of low velocity and viscosity. The factors of heat transfer are analyzed and the field synergy principle is extended. The forces related to the liquid in heat exchanger tubes with twisted-tape insert are analyzed and the influence on the flow field is indicated. With the consideration of the viewpoint of heat conveyance, the methods of reducing the floating resistance and increasing the efficiency of integrated heat transfer are presented. The distributing rules of liquid floating in the tube and heat transfer are obtained by numerical simula-tion which shows that the slick tube has the highest integrated heat transfer coefficient when the twisted-tape insert is about 500～600 mm. The analyses indicate that the length of the twisted-tape insert has wider adjusting area to adapt to the ac-tual work condition to obtained a higher heat transfer coeffi-cient or to lower the floating resistance, and that a higher level of integrated heat transfer coefficient is still kept. The above analyses indicate that the viewpoint of heat conveyance could guide the design of new enhanced heat transfer structures.

Key words: Enhanced heat transfer, Field synergy principle, Heat conveyance, Numerical simulation, Twisted tape