3d Additive Manufactured Heat Pipe For Integration In Components

Many failure fatigue phenomena are related to the high temperature mostly caused by insufficient cooling that cannot effectively transfer the heat generated by the heat source and therefore results in local heat accumulation. Efficient heat transfer that can rapidly reduce the peak temperature is an important method to improve the load capacity and elongate the service life of an engineered component.Unlike the traditional single-phase convective cooling method, the heat pipe is an efficient thermal conductive element and possesses prominent advantages due to its two-phase cycle thermal conductive mechanism and passive self-sufficient heat exchange without using external energy. However, current heat pipe technologies face a number of challenges, such as heat transfer capacity of classic wick structures and difficulty in manufacturing with traditional methods, as well as the limit of the means of transferring heat, and so on. The work reported in this thesis are a novel concept of developing heat pipes integrated with an engineering component based on three-dimensional(3D) additive manufacturing and a new fabrication method of heat pipes so designed. It is anticipated that the proposed new design and manufacturing methodologies for heat pipes can help promote a new horizon for heat pipe applications and explore a future road for developing creative multifunctional mechanical components.3D additive manufacturing is capable of creating complicated internal structures, and thus more effective heat-transferring heat pipes can be expected. A mathematical model is constructed to investigate the influence of trapezoidal grooved wick structures basic parameters such as the effective capillary radius, maximum capillary pressure, porosity, and permeability, to analyze the heat-transfer limits of the micro trapezoidal grooved heat pipes in different working conditions. The importance of the structural parameters of the wick structures to heat-pipe thermal conductivity is illustrated through the analysis of the heat transfer limits.A theory for designing graded wick structures is proposed based on the analysis of the relationship between the competitive effects of capillary pressure and permeability. A novel heat-pipe fabrication method is developed through combining the traditional heat-pipe fabrication process and 3D additive manufacturing. Four grooved heat pipes with micro wick structures were produced by using the EOS M280 metal 3D printer.A test platform was built to measure the heat-transferring performance of the four heat pipes under different working condition. The results reveal that these heat pipes can satisfactorily perform in thermal response and temperature uniformity, and that the micro grooves designed based on the gradient groove theory possess better thermal conductivity than do the traditional straight grooves.Finally, the morphological studies of the inner and outer surfaces of the fabricated heat pipes indicate that the 3D additive manufacturing achieved the desired design effect. The results of this research reveal that with the assistance of 3D additive manufacturing, stronger heat transfer can be achieved even under reduced space occupation rate, and that heat pipes can become a portion of an engineering component so that the latter would have the ability to reach self-temperature-balance. The reported work on the novel heat-pipe design and 3D heat-pipe additive manufacturing is an meaningful reference to future design and fabrication of multifunctional machine components.