Development and expectation of heat-pipe technology and wick research

This paper reviewed the basic working principles of heat pipes and introduced seven types of heat pipes,including thermosyphons,reciprocating heat pipes,pulsating heat pipes,loop heat pipes,rotating heat pipes,micro-heat pipes and variable conductance heat pipes. The applications on the reliability of railway embankment,endurance of machine components,heat dissipation of integrated circuits and resolution of temperature measurement instruments were discussed. The wick structure and the development of composite structures increased permeability and capillary pressure. Material compatibility determines the lifespan of heat pipes and is a key issue to be considered in heat pipe design. Conventional heat pipe manufacturing methods of separately fabricating tubes and wicks were briefly reviewed and discussed. The trends of heat-pipe microminiaturization and structural integration demand more effective heat-pipe shapes and wick structures. A novel heat-pipe fabrication method based on the three dimensional (3D) printing was proposed. This method is able to achieve one-step forming of both the heat-pipe body and the wick structure and directly integrate a heat-pipe device into the structure where heat should be dissipated. As a result,more significant heat-transfer efficiencies and larger economic benefits can be accomplished.